linux-stable/mm/slab_common.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
// SPDX-License-Identifier: GPL-2.0
/*
* Slab allocator functions that are independent of the allocator strategy
*
* (C) 2012 Christoph Lameter <cl@linux.com>
*/
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/poison.h>
#include <linux/interrupt.h>
#include <linux/memory.h>
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
#include <linux/memcontrol.h>
#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>
#include "slab.h"
enum slab_state slab_state;
LIST_HEAD(slab_caches);
DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
static LIST_HEAD(slab_caches_to_rcu_destroy);
static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work);
static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
slab_caches_to_rcu_destroy_workfn);
/*
* Set of flags that will prevent slab merging
*/
#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
SLAB_FAILSLAB | SLAB_KASAN)
#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
SLAB_NOTRACK | SLAB_ACCOUNT)
/*
* Merge control. If this is set then no merging of slab caches will occur.
*/
mm: allow slab_nomerge to be set at build time Some hardened environments want to build kernels with slab_nomerge already set (so that they do not depend on remembering to set the kernel command line option). This is desired to reduce the risk of kernel heap overflows being able to overwrite objects from merged caches and changes the requirements for cache layout control, increasing the difficulty of these attacks. By keeping caches unmerged, these kinds of exploits can usually only damage objects in the same cache (though the risk to metadata exploitation is unchanged). Link: http://lkml.kernel.org/r/20170620230911.GA25238@beast Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Daniel Micay <danielmicay@gmail.com> Cc: David Windsor <dave@nullcore.net> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Daniel Micay <danielmicay@gmail.com> Cc: David Windsor <dave@nullcore.net> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Tejun Heo <tj@kernel.org> Cc: Daniel Mack <daniel@zonque.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: Rik van Riel <riel@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 22:36:40 +00:00
static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
static int __init setup_slab_nomerge(char *str)
{
mm: allow slab_nomerge to be set at build time Some hardened environments want to build kernels with slab_nomerge already set (so that they do not depend on remembering to set the kernel command line option). This is desired to reduce the risk of kernel heap overflows being able to overwrite objects from merged caches and changes the requirements for cache layout control, increasing the difficulty of these attacks. By keeping caches unmerged, these kinds of exploits can usually only damage objects in the same cache (though the risk to metadata exploitation is unchanged). Link: http://lkml.kernel.org/r/20170620230911.GA25238@beast Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Daniel Micay <danielmicay@gmail.com> Cc: David Windsor <dave@nullcore.net> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Daniel Micay <danielmicay@gmail.com> Cc: David Windsor <dave@nullcore.net> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Tejun Heo <tj@kernel.org> Cc: Daniel Mack <daniel@zonque.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: Rik van Riel <riel@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 22:36:40 +00:00
slab_nomerge = true;
return 1;
}
#ifdef CONFIG_SLUB
__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
#endif
__setup("slab_nomerge", setup_slab_nomerge);
/*
* Determine the size of a slab object
*/
unsigned int kmem_cache_size(struct kmem_cache *s)
{
return s->object_size;
}
EXPORT_SYMBOL(kmem_cache_size);
#ifdef CONFIG_DEBUG_VM
static int kmem_cache_sanity_check(const char *name, size_t size)
{
struct kmem_cache *s = NULL;
if (!name || in_interrupt() || size < sizeof(void *) ||
size > KMALLOC_MAX_SIZE) {
pr_err("kmem_cache_create(%s) integrity check failed\n", name);
return -EINVAL;
}
list_for_each_entry(s, &slab_caches, list) {
char tmp;
int res;
/*
* This happens when the module gets unloaded and doesn't
* destroy its slab cache and no-one else reuses the vmalloc
* area of the module. Print a warning.
*/
res = probe_kernel_address(s->name, tmp);
if (res) {
pr_err("Slab cache with size %d has lost its name\n",
s->object_size);
continue;
}
}
WARN_ON(strchr(name, ' ')); /* It confuses parsers */
return 0;
}
#else
static inline int kmem_cache_sanity_check(const char *name, size_t size)
{
return 0;
}
#endif
void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
{
size_t i;
mm: new API kfree_bulk() for SLAB+SLUB allocators This patch introduce a new API call kfree_bulk() for bulk freeing memory objects not bound to a single kmem_cache. Christoph pointed out that it is possible to implement freeing of objects, without knowing the kmem_cache pointer as that information is available from the object's page->slab_cache. Proposing to remove the kmem_cache argument from the bulk free API. Jesper demonstrated that these extra steps per object comes at a performance cost. It is only in the case CONFIG_MEMCG_KMEM is compiled in and activated runtime that these steps are done anyhow. The extra cost is most visible for SLAB allocator, because the SLUB allocator does the page lookup (virt_to_head_page()) anyhow. Thus, the conclusion was to keep the kmem_cache free bulk API with a kmem_cache pointer, but we can still implement a kfree_bulk() API fairly easily. Simply by handling if kmem_cache_free_bulk() gets called with a kmem_cache NULL pointer. This does increase the code size a bit, but implementing a separate kfree_bulk() call would likely increase code size even more. Below benchmarks cost of alloc+free (obj size 256 bytes) on CPU i7-4790K @ 4.00GHz, no PREEMPT and CONFIG_MEMCG_KMEM=y. Code size increase for SLAB: add/remove: 0/0 grow/shrink: 1/0 up/down: 74/0 (74) function old new delta kmem_cache_free_bulk 660 734 +74 SLAB fastpath: 87 cycles(tsc) 21.814 sz - fallback - kmem_cache_free_bulk - kfree_bulk 1 - 103 cycles 25.878 ns - 41 cycles 10.498 ns - 81 cycles 20.312 ns 2 - 94 cycles 23.673 ns - 26 cycles 6.682 ns - 42 cycles 10.649 ns 3 - 92 cycles 23.181 ns - 21 cycles 5.325 ns - 39 cycles 9.950 ns 4 - 90 cycles 22.727 ns - 18 cycles 4.673 ns - 26 cycles 6.693 ns 8 - 89 cycles 22.270 ns - 14 cycles 3.664 ns - 23 cycles 5.835 ns 16 - 88 cycles 22.038 ns - 14 cycles 3.503 ns - 22 cycles 5.543 ns 30 - 89 cycles 22.284 ns - 13 cycles 3.310 ns - 20 cycles 5.197 ns 32 - 88 cycles 22.249 ns - 13 cycles 3.420 ns - 20 cycles 5.166 ns 34 - 88 cycles 22.224 ns - 14 cycles 3.643 ns - 20 cycles 5.170 ns 48 - 88 cycles 22.088 ns - 14 cycles 3.507 ns - 20 cycles 5.203 ns 64 - 88 cycles 22.063 ns - 13 cycles 3.428 ns - 20 cycles 5.152 ns 128 - 89 cycles 22.483 ns - 15 cycles 3.891 ns - 23 cycles 5.885 ns 158 - 89 cycles 22.381 ns - 15 cycles 3.779 ns - 22 cycles 5.548 ns 250 - 91 cycles 22.798 ns - 16 cycles 4.152 ns - 23 cycles 5.967 ns SLAB when enabling MEMCG_KMEM runtime: - kmemcg fastpath: 130 cycles(tsc) 32.684 ns (step:0) 1 - 148 cycles 37.220 ns - 66 cycles 16.622 ns - 66 cycles 16.583 ns 2 - 141 cycles 35.510 ns - 51 cycles 12.820 ns - 58 cycles 14.625 ns 3 - 140 cycles 35.017 ns - 37 cycles 9.326 ns - 33 cycles 8.474 ns 4 - 137 cycles 34.507 ns - 31 cycles 7.888 ns - 33 cycles 8.300 ns 8 - 140 cycles 35.069 ns - 25 cycles 6.461 ns - 25 cycles 6.436 ns 16 - 138 cycles 34.542 ns - 23 cycles 5.945 ns - 22 cycles 5.670 ns 30 - 136 cycles 34.227 ns - 22 cycles 5.502 ns - 22 cycles 5.587 ns 32 - 136 cycles 34.253 ns - 21 cycles 5.475 ns - 21 cycles 5.324 ns 34 - 136 cycles 34.254 ns - 21 cycles 5.448 ns - 20 cycles 5.194 ns 48 - 136 cycles 34.075 ns - 21 cycles 5.458 ns - 21 cycles 5.367 ns 64 - 135 cycles 33.994 ns - 21 cycles 5.350 ns - 21 cycles 5.259 ns 128 - 137 cycles 34.446 ns - 23 cycles 5.816 ns - 22 cycles 5.688 ns 158 - 137 cycles 34.379 ns - 22 cycles 5.727 ns - 22 cycles 5.602 ns 250 - 138 cycles 34.755 ns - 24 cycles 6.093 ns - 23 cycles 5.986 ns Code size increase for SLUB: function old new delta kmem_cache_free_bulk 717 799 +82 SLUB benchmark: SLUB fastpath: 46 cycles(tsc) 11.691 ns (step:0) sz - fallback - kmem_cache_free_bulk - kfree_bulk 1 - 61 cycles 15.486 ns - 53 cycles 13.364 ns - 57 cycles 14.464 ns 2 - 54 cycles 13.703 ns - 32 cycles 8.110 ns - 33 cycles 8.482 ns 3 - 53 cycles 13.272 ns - 25 cycles 6.362 ns - 27 cycles 6.947 ns 4 - 51 cycles 12.994 ns - 24 cycles 6.087 ns - 24 cycles 6.078 ns 8 - 50 cycles 12.576 ns - 21 cycles 5.354 ns - 22 cycles 5.513 ns 16 - 49 cycles 12.368 ns - 20 cycles 5.054 ns - 20 cycles 5.042 ns 30 - 49 cycles 12.273 ns - 18 cycles 4.748 ns - 19 cycles 4.758 ns 32 - 49 cycles 12.401 ns - 19 cycles 4.821 ns - 19 cycles 4.810 ns 34 - 98 cycles 24.519 ns - 24 cycles 6.154 ns - 24 cycles 6.157 ns 48 - 83 cycles 20.833 ns - 21 cycles 5.446 ns - 21 cycles 5.429 ns 64 - 75 cycles 18.891 ns - 20 cycles 5.247 ns - 20 cycles 5.238 ns 128 - 93 cycles 23.271 ns - 27 cycles 6.856 ns - 27 cycles 6.823 ns 158 - 102 cycles 25.581 ns - 30 cycles 7.714 ns - 30 cycles 7.695 ns 250 - 107 cycles 26.917 ns - 38 cycles 9.514 ns - 38 cycles 9.506 ns SLUB when enabling MEMCG_KMEM runtime: - kmemcg fastpath: 71 cycles(tsc) 17.897 ns (step:0) 1 - 85 cycles 21.484 ns - 78 cycles 19.569 ns - 75 cycles 18.938 ns 2 - 81 cycles 20.363 ns - 45 cycles 11.258 ns - 44 cycles 11.076 ns 3 - 78 cycles 19.709 ns - 33 cycles 8.354 ns - 32 cycles 8.044 ns 4 - 77 cycles 19.430 ns - 28 cycles 7.216 ns - 28 cycles 7.003 ns 8 - 101 cycles 25.288 ns - 23 cycles 5.849 ns - 23 cycles 5.787 ns 16 - 76 cycles 19.148 ns - 20 cycles 5.162 ns - 20 cycles 5.081 ns 30 - 76 cycles 19.067 ns - 19 cycles 4.868 ns - 19 cycles 4.821 ns 32 - 76 cycles 19.052 ns - 19 cycles 4.857 ns - 19 cycles 4.815 ns 34 - 121 cycles 30.291 ns - 25 cycles 6.333 ns - 25 cycles 6.268 ns 48 - 108 cycles 27.111 ns - 21 cycles 5.498 ns - 21 cycles 5.458 ns 64 - 100 cycles 25.164 ns - 20 cycles 5.242 ns - 20 cycles 5.229 ns 128 - 155 cycles 38.976 ns - 27 cycles 6.886 ns - 27 cycles 6.892 ns 158 - 132 cycles 33.034 ns - 30 cycles 7.711 ns - 30 cycles 7.728 ns 250 - 130 cycles 32.612 ns - 38 cycles 9.560 ns - 38 cycles 9.549 ns Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-15 21:54:00 +00:00
for (i = 0; i < nr; i++) {
if (s)
kmem_cache_free(s, p[i]);
else
kfree(p[i]);
}
}
int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
void **p)
{
size_t i;
for (i = 0; i < nr; i++) {
void *x = p[i] = kmem_cache_alloc(s, flags);
if (!x) {
__kmem_cache_free_bulk(s, i, p);
return 0;
}
}
return i;
}
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
LIST_HEAD(slab_root_caches);
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
void slab_init_memcg_params(struct kmem_cache *s)
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
{
s->memcg_params.root_cache = NULL;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
INIT_LIST_HEAD(&s->memcg_params.children);
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
}
static int init_memcg_params(struct kmem_cache *s,
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
struct memcg_cache_array *arr;
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
if (root_cache) {
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
s->memcg_params.root_cache = root_cache;
s->memcg_params.memcg = memcg;
INIT_LIST_HEAD(&s->memcg_params.children_node);
slab: link memcg kmem_caches on their associated memory cgroup With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. While a memcg kmem_cache is listed on its root cache's ->children list, there is no direct way to iterate all kmem_caches which are assocaited with a memory cgroup. The only way to iterate them is walking all caches while filtering out caches which don't match, which would be most of them. This makes memcg destruction operations O(N^2) where N is the total number of slab caches which can be huge. This combined with the synchronous RCU operations can tie up a CPU and affect the whole machine for many hours when memory reclaim triggers offlining and destruction of the stale memcgs. This patch adds mem_cgroup->kmem_caches list which goes through memcg_cache_params->kmem_caches_node of all kmem_caches which are associated with the memcg. All memcg specific iterations, including stat file access, are updated to use the new list instead. Link: http://lkml.kernel.org/r/20170117235411.9408-6-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:21 +00:00
INIT_LIST_HEAD(&s->memcg_params.kmem_caches_node);
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
return 0;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
}
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
slab_init_memcg_params(s);
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
if (!memcg_nr_cache_ids)
return 0;
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
mm: memcontrol: use vmalloc fallback for large kmem memcg arrays For quick per-memcg indexing, slab caches and list_lru structures maintain linear arrays of descriptors. As the number of concurrent memory cgroups in the system goes up, this requires large contiguous allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every existing slab cache and list_lru, which can easily fail on loaded systems. E.g.: mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Call Trace: ? __alloc_pages_direct_compact+0x4c/0x110 __alloc_pages_nodemask+0xf50/0x1430 alloc_pages_current+0x60/0xc0 kmalloc_order_trace+0x29/0x1b0 __kmalloc+0x1f4/0x320 memcg_update_all_list_lrus+0xca/0x2e0 mem_cgroup_css_alloc+0x612/0x670 cgroup_apply_control_enable+0x19e/0x360 cgroup_mkdir+0x322/0x490 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xd0/0x120 SyS_mkdirat+0x6c/0xe0 SyS_mkdir+0x14/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Mem-Info: active_anon:2965 inactive_anon:19 isolated_anon:0 active_file:100270 inactive_file:98846 isolated_file:0 unevictable:0 dirty:0 writeback:0 unstable:0 slab_reclaimable:7328 slab_unreclaimable:16402 mapped:771 shmem:52 pagetables:278 bounce:0 free:13718 free_pcp:0 free_cma:0 This output is from an artificial reproducer, but we have repeatedly observed order-7 failures in production in the Facebook fleet. These systems become useless as they cannot run more jobs, even though there is plenty of memory to allocate 128 individual pages. Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays prove too large for allocating them physically contiguous. Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-03 23:16:10 +00:00
arr = kvzalloc(sizeof(struct memcg_cache_array) +
memcg_nr_cache_ids * sizeof(void *),
GFP_KERNEL);
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
if (!arr)
return -ENOMEM;
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
return 0;
}
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
static void destroy_memcg_params(struct kmem_cache *s)
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
{
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
if (is_root_cache(s))
mm: memcontrol: use vmalloc fallback for large kmem memcg arrays For quick per-memcg indexing, slab caches and list_lru structures maintain linear arrays of descriptors. As the number of concurrent memory cgroups in the system goes up, this requires large contiguous allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every existing slab cache and list_lru, which can easily fail on loaded systems. E.g.: mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Call Trace: ? __alloc_pages_direct_compact+0x4c/0x110 __alloc_pages_nodemask+0xf50/0x1430 alloc_pages_current+0x60/0xc0 kmalloc_order_trace+0x29/0x1b0 __kmalloc+0x1f4/0x320 memcg_update_all_list_lrus+0xca/0x2e0 mem_cgroup_css_alloc+0x612/0x670 cgroup_apply_control_enable+0x19e/0x360 cgroup_mkdir+0x322/0x490 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xd0/0x120 SyS_mkdirat+0x6c/0xe0 SyS_mkdir+0x14/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Mem-Info: active_anon:2965 inactive_anon:19 isolated_anon:0 active_file:100270 inactive_file:98846 isolated_file:0 unevictable:0 dirty:0 writeback:0 unstable:0 slab_reclaimable:7328 slab_unreclaimable:16402 mapped:771 shmem:52 pagetables:278 bounce:0 free:13718 free_pcp:0 free_cma:0 This output is from an artificial reproducer, but we have repeatedly observed order-7 failures in production in the Facebook fleet. These systems become useless as they cannot run more jobs, even though there is plenty of memory to allocate 128 individual pages. Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays prove too large for allocating them physically contiguous. Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-03 23:16:10 +00:00
kvfree(rcu_access_pointer(s->memcg_params.memcg_caches));
}
static void free_memcg_params(struct rcu_head *rcu)
{
struct memcg_cache_array *old;
old = container_of(rcu, struct memcg_cache_array, rcu);
kvfree(old);
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
}
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
static int update_memcg_params(struct kmem_cache *s, int new_array_size)
{
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
struct memcg_cache_array *old, *new;
mm: memcontrol: use vmalloc fallback for large kmem memcg arrays For quick per-memcg indexing, slab caches and list_lru structures maintain linear arrays of descriptors. As the number of concurrent memory cgroups in the system goes up, this requires large contiguous allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every existing slab cache and list_lru, which can easily fail on loaded systems. E.g.: mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Call Trace: ? __alloc_pages_direct_compact+0x4c/0x110 __alloc_pages_nodemask+0xf50/0x1430 alloc_pages_current+0x60/0xc0 kmalloc_order_trace+0x29/0x1b0 __kmalloc+0x1f4/0x320 memcg_update_all_list_lrus+0xca/0x2e0 mem_cgroup_css_alloc+0x612/0x670 cgroup_apply_control_enable+0x19e/0x360 cgroup_mkdir+0x322/0x490 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xd0/0x120 SyS_mkdirat+0x6c/0xe0 SyS_mkdir+0x14/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Mem-Info: active_anon:2965 inactive_anon:19 isolated_anon:0 active_file:100270 inactive_file:98846 isolated_file:0 unevictable:0 dirty:0 writeback:0 unstable:0 slab_reclaimable:7328 slab_unreclaimable:16402 mapped:771 shmem:52 pagetables:278 bounce:0 free:13718 free_pcp:0 free_cma:0 This output is from an artificial reproducer, but we have repeatedly observed order-7 failures in production in the Facebook fleet. These systems become useless as they cannot run more jobs, even though there is plenty of memory to allocate 128 individual pages. Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays prove too large for allocating them physically contiguous. Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-03 23:16:10 +00:00
new = kvzalloc(sizeof(struct memcg_cache_array) +
new_array_size * sizeof(void *), GFP_KERNEL);
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
if (!new)
return -ENOMEM;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
old = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
if (old)
memcpy(new->entries, old->entries,
memcg_nr_cache_ids * sizeof(void *));
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
rcu_assign_pointer(s->memcg_params.memcg_caches, new);
if (old)
mm: memcontrol: use vmalloc fallback for large kmem memcg arrays For quick per-memcg indexing, slab caches and list_lru structures maintain linear arrays of descriptors. As the number of concurrent memory cgroups in the system goes up, this requires large contiguous allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every existing slab cache and list_lru, which can easily fail on loaded systems. E.g.: mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Call Trace: ? __alloc_pages_direct_compact+0x4c/0x110 __alloc_pages_nodemask+0xf50/0x1430 alloc_pages_current+0x60/0xc0 kmalloc_order_trace+0x29/0x1b0 __kmalloc+0x1f4/0x320 memcg_update_all_list_lrus+0xca/0x2e0 mem_cgroup_css_alloc+0x612/0x670 cgroup_apply_control_enable+0x19e/0x360 cgroup_mkdir+0x322/0x490 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xd0/0x120 SyS_mkdirat+0x6c/0xe0 SyS_mkdir+0x14/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Mem-Info: active_anon:2965 inactive_anon:19 isolated_anon:0 active_file:100270 inactive_file:98846 isolated_file:0 unevictable:0 dirty:0 writeback:0 unstable:0 slab_reclaimable:7328 slab_unreclaimable:16402 mapped:771 shmem:52 pagetables:278 bounce:0 free:13718 free_pcp:0 free_cma:0 This output is from an artificial reproducer, but we have repeatedly observed order-7 failures in production in the Facebook fleet. These systems become useless as they cannot run more jobs, even though there is plenty of memory to allocate 128 individual pages. Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays prove too large for allocating them physically contiguous. Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-03 23:16:10 +00:00
call_rcu(&old->rcu, free_memcg_params);
return 0;
}
memcg: allocate memory for memcg caches whenever a new memcg appears Every cache that is considered a root cache (basically the "original" caches, tied to the root memcg/no-memcg) will have an array that should be large enough to store a cache pointer per each memcg in the system. Theoreticaly, this is as high as 1 << sizeof(css_id), which is currently in the 64k pointers range. Most of the time, we won't be using that much. What goes in this patch, is a simple scheme to dynamically allocate such an array, in order to minimize memory usage for memcg caches. Because we would also like to avoid allocations all the time, at least for now, the array will only grow. It will tend to be big enough to hold the maximum number of kmem-limited memcgs ever achieved. We'll allocate it to be a minimum of 64 kmem-limited memcgs. When we have more than that, we'll start doubling the size of this array every time the limit is reached. Because we are only considering kmem limited memcgs, a natural point for this to happen is when we write to the limit. At that point, we already have set_limit_mutex held, so that will become our natural synchronization mechanism. Signed-off-by: Glauber Costa <glommer@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <fweisbec@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: JoonSoo Kim <js1304@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Rik van Riel <riel@redhat.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 22:22:38 +00:00
int memcg_update_all_caches(int num_memcgs)
{
struct kmem_cache *s;
int ret = 0;
memcg: add rwsem to synchronize against memcg_caches arrays relocation We need a stable value of memcg_nr_cache_ids in kmem_cache_create() (memcg_alloc_cache_params() wants it for root caches), where we only hold the slab_mutex and no memcg-related locks. As a result, we have to update memcg_nr_cache_ids under the slab_mutex, which we can only take on the slab's side (see memcg_update_array_size). This looks awkward and will become even worse when per-memcg list_lru is introduced, which also wants stable access to memcg_nr_cache_ids. To get rid of this dependency between the memcg_nr_cache_ids and the slab_mutex, this patch introduces a special rwsem. The rwsem is held for writing during memcg_caches arrays relocation and memcg_nr_cache_ids updates. Therefore one can take it for reading to get a stable access to memcg_caches arrays and/or memcg_nr_cache_ids. Currently the semaphore is taken for reading only from kmem_cache_create, right before taking the slab_mutex, so right now there's no much point in using rwsem instead of mutex. However, once list_lru is made per-memcg it will allow list_lru initializations to proceed concurrently. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:01 +00:00
mutex_lock(&slab_mutex);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
list_for_each_entry(s, &slab_root_caches, root_caches_node) {
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
ret = update_memcg_params(s, num_memcgs);
memcg: allocate memory for memcg caches whenever a new memcg appears Every cache that is considered a root cache (basically the "original" caches, tied to the root memcg/no-memcg) will have an array that should be large enough to store a cache pointer per each memcg in the system. Theoreticaly, this is as high as 1 << sizeof(css_id), which is currently in the 64k pointers range. Most of the time, we won't be using that much. What goes in this patch, is a simple scheme to dynamically allocate such an array, in order to minimize memory usage for memcg caches. Because we would also like to avoid allocations all the time, at least for now, the array will only grow. It will tend to be big enough to hold the maximum number of kmem-limited memcgs ever achieved. We'll allocate it to be a minimum of 64 kmem-limited memcgs. When we have more than that, we'll start doubling the size of this array every time the limit is reached. Because we are only considering kmem limited memcgs, a natural point for this to happen is when we write to the limit. At that point, we already have set_limit_mutex held, so that will become our natural synchronization mechanism. Signed-off-by: Glauber Costa <glommer@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <fweisbec@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: JoonSoo Kim <js1304@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Rik van Riel <riel@redhat.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 22:22:38 +00:00
/*
* Instead of freeing the memory, we'll just leave the caches
* up to this point in an updated state.
*/
if (ret)
memcg: add rwsem to synchronize against memcg_caches arrays relocation We need a stable value of memcg_nr_cache_ids in kmem_cache_create() (memcg_alloc_cache_params() wants it for root caches), where we only hold the slab_mutex and no memcg-related locks. As a result, we have to update memcg_nr_cache_ids under the slab_mutex, which we can only take on the slab's side (see memcg_update_array_size). This looks awkward and will become even worse when per-memcg list_lru is introduced, which also wants stable access to memcg_nr_cache_ids. To get rid of this dependency between the memcg_nr_cache_ids and the slab_mutex, this patch introduces a special rwsem. The rwsem is held for writing during memcg_caches arrays relocation and memcg_nr_cache_ids updates. Therefore one can take it for reading to get a stable access to memcg_caches arrays and/or memcg_nr_cache_ids. Currently the semaphore is taken for reading only from kmem_cache_create, right before taking the slab_mutex, so right now there's no much point in using rwsem instead of mutex. However, once list_lru is made per-memcg it will allow list_lru initializations to proceed concurrently. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:01 +00:00
break;
memcg: allocate memory for memcg caches whenever a new memcg appears Every cache that is considered a root cache (basically the "original" caches, tied to the root memcg/no-memcg) will have an array that should be large enough to store a cache pointer per each memcg in the system. Theoreticaly, this is as high as 1 << sizeof(css_id), which is currently in the 64k pointers range. Most of the time, we won't be using that much. What goes in this patch, is a simple scheme to dynamically allocate such an array, in order to minimize memory usage for memcg caches. Because we would also like to avoid allocations all the time, at least for now, the array will only grow. It will tend to be big enough to hold the maximum number of kmem-limited memcgs ever achieved. We'll allocate it to be a minimum of 64 kmem-limited memcgs. When we have more than that, we'll start doubling the size of this array every time the limit is reached. Because we are only considering kmem limited memcgs, a natural point for this to happen is when we write to the limit. At that point, we already have set_limit_mutex held, so that will become our natural synchronization mechanism. Signed-off-by: Glauber Costa <glommer@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <fweisbec@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: JoonSoo Kim <js1304@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Rik van Riel <riel@redhat.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 22:22:38 +00:00
}
mutex_unlock(&slab_mutex);
return ret;
}
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
void memcg_link_cache(struct kmem_cache *s)
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
{
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
if (is_root_cache(s)) {
list_add(&s->root_caches_node, &slab_root_caches);
} else {
list_add(&s->memcg_params.children_node,
&s->memcg_params.root_cache->memcg_params.children);
list_add(&s->memcg_params.kmem_caches_node,
&s->memcg_params.memcg->kmem_caches);
}
}
static void memcg_unlink_cache(struct kmem_cache *s)
{
if (is_root_cache(s)) {
list_del(&s->root_caches_node);
} else {
list_del(&s->memcg_params.children_node);
list_del(&s->memcg_params.kmem_caches_node);
}
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
}
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
#else
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
static inline int init_memcg_params(struct kmem_cache *s,
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
{
return 0;
}
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
static inline void destroy_memcg_params(struct kmem_cache *s)
memcg: move memcg_{alloc,free}_cache_params to slab_common.c The only reason why they live in memcontrol.c is that we get/put css reference to the owner memory cgroup in them. However, we can do that in memcg_{un,}register_cache. OTOH, there are several reasons to move them to slab_common.c. First, I think that the less public interface functions we have in memcontrol.h the better. Since the functions I move don't depend on memcontrol, I think it's worth making them private to slab, especially taking into account that the arrays are defined on the slab's side too. Second, the way how per-memcg arrays are updated looks rather awkward: it proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c (memcg_update_all_caches) and back to memcontrol.c again (memcg_update_array_size). In the following patches I move the function relocating the arrays (memcg_update_array_size) to slab_common.c and therefore get rid this circular call path. I think we should have the cache allocation stuff in the same place where we have relocation, because it's easier to follow the code then. So I move arrays alloc/free functions to slab_common.c too. The third point isn't obvious. I'm going to make the list_lru structure per-memcg to allow targeted kmem reclaim. That means we will have per-memcg arrays in list_lrus too. It turns out that it's much easier to update these arrays in list_lru.c rather than in memcontrol.c, because all the stuff we need is defined there. This patch makes memcg caches arrays allocation path conform that of the upcoming list_lru. So let's move these functions to slab_common.c and make them static. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:28:43 +00:00
{
}
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
static inline void memcg_unlink_cache(struct kmem_cache *s)
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
{
}
#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
memcg: allocate memory for memcg caches whenever a new memcg appears Every cache that is considered a root cache (basically the "original" caches, tied to the root memcg/no-memcg) will have an array that should be large enough to store a cache pointer per each memcg in the system. Theoreticaly, this is as high as 1 << sizeof(css_id), which is currently in the 64k pointers range. Most of the time, we won't be using that much. What goes in this patch, is a simple scheme to dynamically allocate such an array, in order to minimize memory usage for memcg caches. Because we would also like to avoid allocations all the time, at least for now, the array will only grow. It will tend to be big enough to hold the maximum number of kmem-limited memcgs ever achieved. We'll allocate it to be a minimum of 64 kmem-limited memcgs. When we have more than that, we'll start doubling the size of this array every time the limit is reached. Because we are only considering kmem limited memcgs, a natural point for this to happen is when we write to the limit. At that point, we already have set_limit_mutex held, so that will become our natural synchronization mechanism. Signed-off-by: Glauber Costa <glommer@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <fweisbec@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: JoonSoo Kim <js1304@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Rik van Riel <riel@redhat.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 22:22:38 +00:00
/*
* Find a mergeable slab cache
*/
int slab_unmergeable(struct kmem_cache *s)
{
if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
return 1;
if (!is_root_cache(s))
return 1;
if (s->ctor)
return 1;
/*
* We may have set a slab to be unmergeable during bootstrap.
*/
if (s->refcount < 0)
return 1;
return 0;
}
struct kmem_cache *find_mergeable(size_t size, size_t align,
unsigned long flags, const char *name, void (*ctor)(void *))
{
struct kmem_cache *s;
if (slab_nomerge)
return NULL;
if (ctor)
return NULL;
size = ALIGN(size, sizeof(void *));
align = calculate_alignment(flags, align, size);
size = ALIGN(size, align);
flags = kmem_cache_flags(size, flags, name, NULL);
if (flags & SLAB_NEVER_MERGE)
return NULL;
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
list_for_each_entry_reverse(s, &slab_root_caches, root_caches_node) {
if (slab_unmergeable(s))
continue;
if (size > s->size)
continue;
if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
continue;
/*
* Check if alignment is compatible.
* Courtesy of Adrian Drzewiecki
*/
if ((s->size & ~(align - 1)) != s->size)
continue;
if (s->size - size >= sizeof(void *))
continue;
mm/slab: fix unalignment problem on Malta with EVA due to slab merge Unlike SLUB, sometimes, object isn't started at the beginning of the slab in SLAB. This causes the unalignment problem after slab merging is supported by commit 12220dea07f1 ("mm/slab: support slab merge"). Following is the report from Markos that fail to boot on Malta with EVA. Calibrating delay loop... 19.86 BogoMIPS (lpj=99328) pid_max: default: 32768 minimum: 301 Mount-cache hash table entries: 4096 (order: 0, 16384 bytes) Mountpoint-cache hash table entries: 4096 (order: 0, 16384 bytes) Kernel bug detected[#1]: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.17.0-05639-g12220dea07f1 #1631 task: 1f04f5d8 ti: 1f050000 task.ti: 1f050000 epc : 80141190 alloc_unbound_pwq+0x234/0x304 Not tainted ra : 80141184 alloc_unbound_pwq+0x228/0x304 Process swapper/0 (pid: 1, threadinfo=1f050000, task=1f04f5d8, tls=00000000) Call Trace: alloc_unbound_pwq+0x234/0x304 apply_workqueue_attrs+0x11c/0x294 __alloc_workqueue_key+0x23c/0x470 init_workqueues+0x320/0x400 do_one_initcall+0xe8/0x23c kernel_init_freeable+0x9c/0x224 kernel_init+0x10/0x100 ret_from_kernel_thread+0x14/0x1c [ end trace cb88537fdc8fa200 ] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b alloc_unbound_pwq() allocates slab object from pool_workqueue. This kmem_cache requires 256 bytes alignment, but, current merging code doesn't honor that, and merge it with kmalloc-256. kmalloc-256 requires only cacheline size alignment so that above failure occurs. However, in x86, kmalloc-256 is luckily aligned in 256 bytes, so the problem didn't happen on it. To fix this problem, this patch introduces alignment mismatch check in find_mergeable(). This will fix the problem. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reported-by: Markos Chandras <Markos.Chandras@imgtec.com> Tested-by: Markos Chandras <Markos.Chandras@imgtec.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-11-13 23:19:25 +00:00
if (IS_ENABLED(CONFIG_SLAB) && align &&
(align > s->align || s->align % align))
continue;
return s;
}
return NULL;
}
/*
* Figure out what the alignment of the objects will be given a set of
* flags, a user specified alignment and the size of the objects.
*/
unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size)
{
/*
* If the user wants hardware cache aligned objects then follow that
* suggestion if the object is sufficiently large.
*
* The hardware cache alignment cannot override the specified
* alignment though. If that is greater then use it.
*/
if (flags & SLAB_HWCACHE_ALIGN) {
unsigned long ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
align = max(align, ralign);
}
if (align < ARCH_SLAB_MINALIGN)
align = ARCH_SLAB_MINALIGN;
return ALIGN(align, sizeof(void *));
}
static struct kmem_cache *create_cache(const char *name,
size_t object_size, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *),
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
struct kmem_cache *s;
int err;
err = -ENOMEM;
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
if (!s)
goto out;
s->name = name;
s->object_size = object_size;
s->size = size;
s->align = align;
s->ctor = ctor;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
err = init_memcg_params(s, memcg, root_cache);
if (err)
goto out_free_cache;
err = __kmem_cache_create(s, flags);
if (err)
goto out_free_cache;
s->refcount = 1;
list_add(&s->list, &slab_caches);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
memcg_link_cache(s);
out:
if (err)
return ERR_PTR(err);
return s;
out_free_cache:
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
destroy_memcg_params(s);
kmem_cache_free(kmem_cache, s);
goto out;
}
/*
* kmem_cache_create - Create a cache.
* @name: A string which is used in /proc/slabinfo to identify this cache.
* @size: The size of objects to be created in this cache.
* @align: The required alignment for the objects.
* @flags: SLAB flags
* @ctor: A constructor for the objects.
*
* Returns a ptr to the cache on success, NULL on failure.
* Cannot be called within a interrupt, but can be interrupted.
* The @ctor is run when new pages are allocated by the cache.
*
* The flags are
*
* %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
* to catch references to uninitialised memory.
*
* %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
* for buffer overruns.
*
* %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
* cacheline. This can be beneficial if you're counting cycles as closely
* as davem.
*/
struct kmem_cache *
kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
{
struct kmem_cache *s = NULL;
const char *cache_name;
int err;
get_online_cpus();
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
get_online_mems();
memcg: add rwsem to synchronize against memcg_caches arrays relocation We need a stable value of memcg_nr_cache_ids in kmem_cache_create() (memcg_alloc_cache_params() wants it for root caches), where we only hold the slab_mutex and no memcg-related locks. As a result, we have to update memcg_nr_cache_ids under the slab_mutex, which we can only take on the slab's side (see memcg_update_array_size). This looks awkward and will become even worse when per-memcg list_lru is introduced, which also wants stable access to memcg_nr_cache_ids. To get rid of this dependency between the memcg_nr_cache_ids and the slab_mutex, this patch introduces a special rwsem. The rwsem is held for writing during memcg_caches arrays relocation and memcg_nr_cache_ids updates. Therefore one can take it for reading to get a stable access to memcg_caches arrays and/or memcg_nr_cache_ids. Currently the semaphore is taken for reading only from kmem_cache_create, right before taking the slab_mutex, so right now there's no much point in using rwsem instead of mutex. However, once list_lru is made per-memcg it will allow list_lru initializations to proceed concurrently. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:01 +00:00
memcg_get_cache_ids();
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
mutex_lock(&slab_mutex);
err = kmem_cache_sanity_check(name, size);
if (err) {
goto out_unlock;
}
/* Refuse requests with allocator specific flags */
if (flags & ~SLAB_FLAGS_PERMITTED) {
err = -EINVAL;
goto out_unlock;
}
/*
* Some allocators will constraint the set of valid flags to a subset
* of all flags. We expect them to define CACHE_CREATE_MASK in this
* case, and we'll just provide them with a sanitized version of the
* passed flags.
*/
flags &= CACHE_CREATE_MASK;
s = __kmem_cache_alias(name, size, align, flags, ctor);
if (s)
goto out_unlock;
cache_name = kstrdup_const(name, GFP_KERNEL);
if (!cache_name) {
err = -ENOMEM;
goto out_unlock;
}
s = create_cache(cache_name, size, size,
calculate_alignment(flags, align, size),
flags, ctor, NULL, NULL);
if (IS_ERR(s)) {
err = PTR_ERR(s);
kfree_const(cache_name);
}
out_unlock:
mutex_unlock(&slab_mutex);
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
memcg: add rwsem to synchronize against memcg_caches arrays relocation We need a stable value of memcg_nr_cache_ids in kmem_cache_create() (memcg_alloc_cache_params() wants it for root caches), where we only hold the slab_mutex and no memcg-related locks. As a result, we have to update memcg_nr_cache_ids under the slab_mutex, which we can only take on the slab's side (see memcg_update_array_size). This looks awkward and will become even worse when per-memcg list_lru is introduced, which also wants stable access to memcg_nr_cache_ids. To get rid of this dependency between the memcg_nr_cache_ids and the slab_mutex, this patch introduces a special rwsem. The rwsem is held for writing during memcg_caches arrays relocation and memcg_nr_cache_ids updates. Therefore one can take it for reading to get a stable access to memcg_caches arrays and/or memcg_nr_cache_ids. Currently the semaphore is taken for reading only from kmem_cache_create, right before taking the slab_mutex, so right now there's no much point in using rwsem instead of mutex. However, once list_lru is made per-memcg it will allow list_lru initializations to proceed concurrently. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:01 +00:00
memcg_put_cache_ids();
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
put_online_mems();
put_online_cpus();
slab: fix wrong retval on kmem_cache_create_memcg error path On kmem_cache_create_memcg() error path we set 'err', but leave 's' (the new cache ptr) undefined. The latter can be NULL if we could not allocate the cache, or pointing to a freed area if we failed somewhere later while trying to initialize it. Initially we checked 'err' immediately before exiting the function and returned NULL if it was set ignoring the value of 's': out_unlock: ... if (err) { /* report error */ return NULL; } return s; Recently this check was, in fact, broken by commit f717eb3abb5e ("slab: do not panic if we fail to create memcg cache"), which turned it to: out_unlock: ... if (err && !memcg) { /* report error */ return NULL; } return s; As a result, if we are failing creating a cache for a memcg, we will skip the check and return 's' that can contain crap. Obviously, commit f717eb3abb5e intended not to return crap on error allocating a cache for a memcg, but only to remove the error reporting in this case, so the check should look like this: out_unlock: ... if (err) { if (!memcg) return NULL; /* report error */ return NULL; } return s; [rientjes@google.com: despaghettification] [vdavydov@parallels.com: patch monkeying] Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Dave Jones <davej@redhat.com> Reported-by: Dave Jones <davej@redhat.com> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-29 22:05:48 +00:00
if (err) {
if (flags & SLAB_PANIC)
panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
name, err);
else {
pr_warn("kmem_cache_create(%s) failed with error %d\n",
name, err);
dump_stack();
}
return NULL;
}
return s;
}
EXPORT_SYMBOL(kmem_cache_create);
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
{
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
LIST_HEAD(to_destroy);
struct kmem_cache *s, *s2;
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
/*
* On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
* @slab_caches_to_rcu_destroy list. The slab pages are freed
* through RCU and and the associated kmem_cache are dereferenced
* while freeing the pages, so the kmem_caches should be freed only
* after the pending RCU operations are finished. As rcu_barrier()
* is a pretty slow operation, we batch all pending destructions
* asynchronously.
*/
mutex_lock(&slab_mutex);
list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy);
mutex_unlock(&slab_mutex);
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
if (list_empty(&to_destroy))
return;
rcu_barrier();
list_for_each_entry_safe(s, s2, &to_destroy, list) {
#ifdef SLAB_SUPPORTS_SYSFS
sysfs_slab_release(s);
#else
slab_kmem_cache_release(s);
#endif
}
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
}
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
static int shutdown_cache(struct kmem_cache *s)
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
{
kasan: drain quarantine of memcg slab objects Per memcg slab accounting and kasan have a problem with kmem_cache destruction. - kmem_cache_create() allocates a kmem_cache, which is used for allocations from processes running in root (top) memcg. - Processes running in non root memcg and allocating with either __GFP_ACCOUNT or from a SLAB_ACCOUNT cache use a per memcg kmem_cache. - Kasan catches use-after-free by having kfree() and kmem_cache_free() defer freeing of objects. Objects are placed in a quarantine. - kmem_cache_destroy() destroys root and non root kmem_caches. It takes care to drain the quarantine of objects from the root memcg's kmem_cache, but ignores objects associated with non root memcg. This causes leaks because quarantined per memcg objects refer to per memcg kmem cache being destroyed. To see the problem: 1) create a slab cache with kmem_cache_create(,,,SLAB_ACCOUNT,) 2) from non root memcg, allocate and free a few objects from cache 3) dispose of the cache with kmem_cache_destroy() kmem_cache_destroy() will trigger a "Slab cache still has objects" warning indicating that the per memcg kmem_cache structure was leaked. Fix the leak by draining kasan quarantined objects allocated from non root memcg. Racing memcg deletion is tricky, but handled. kmem_cache_destroy() => shutdown_memcg_caches() => __shutdown_memcg_cache() => shutdown_cache() flushes per memcg quarantined objects, even if that memcg has been rmdir'd and gone through memcg_deactivate_kmem_caches(). This leak only affects destroyed SLAB_ACCOUNT kmem caches when kasan is enabled. So I don't think it's worth patching stable kernels. Link: http://lkml.kernel.org/r/1482257462-36948-1-git-send-email-gthelen@google.com Signed-off-by: Greg Thelen <gthelen@google.com> Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 23:00:05 +00:00
/* free asan quarantined objects */
kasan_cache_shutdown(s);
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
if (__kmem_cache_shutdown(s) != 0)
return -EBUSY;
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
memcg_unlink_cache(s);
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
list_del(&s->list);
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
if (s->flags & SLAB_TYPESAFE_BY_RCU) {
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
schedule_work(&slab_caches_to_rcu_destroy_work);
} else {
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
#ifdef SLAB_SUPPORTS_SYSFS
sysfs_slab_release(s);
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
#else
slab_kmem_cache_release(s);
#endif
}
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
return 0;
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
}
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
/*
* memcg_create_kmem_cache - Create a cache for a memory cgroup.
* @memcg: The memory cgroup the new cache is for.
* @root_cache: The parent of the new cache.
*
* This function attempts to create a kmem cache that will serve allocation
* requests going from @memcg to @root_cache. The new cache inherits properties
* from its parent.
*/
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
void memcg_create_kmem_cache(struct mem_cgroup *memcg,
struct kmem_cache *root_cache)
{
static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
struct cgroup_subsys_state *css = &memcg->css;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
struct memcg_cache_array *arr;
memcg, slab: simplify synchronization scheme At present, we have the following mutexes protecting data related to per memcg kmem caches: - slab_mutex. This one is held during the whole kmem cache creation and destruction paths. We also take it when updating per root cache memcg_caches arrays (see memcg_update_all_caches). As a result, taking it guarantees there will be no changes to any kmem cache (including per memcg). Why do we need something else then? The point is it is private to slab implementation and has some internal dependencies with other mutexes (get_online_cpus). So we just don't want to rely upon it and prefer to introduce additional mutexes instead. - activate_kmem_mutex. Initially it was added to synchronize initializing kmem limit (memcg_activate_kmem). However, since we can grow per root cache memcg_caches arrays only on kmem limit initialization (see memcg_update_all_caches), we also employ it to protect against memcg_caches arrays relocation (e.g. see __kmem_cache_destroy_memcg_children). - We have a convention not to take slab_mutex in memcontrol.c, but we want to walk over per memcg memcg_slab_caches lists there (e.g. for destroying all memcg caches on offline). So we have per memcg slab_caches_mutex's protecting those lists. The mutexes are taken in the following order: activate_kmem_mutex -> slab_mutex -> memcg::slab_caches_mutex Such a syncrhonization scheme has a number of flaws, for instance: - We can't call kmem_cache_{destroy,shrink} while walking over a memcg::memcg_slab_caches list due to locking order. As a result, in mem_cgroup_destroy_all_caches we schedule the memcg_cache_params::destroy work shrinking and destroying the cache. - We don't have a mutex to synchronize per memcg caches destruction between memcg offline (mem_cgroup_destroy_all_caches) and root cache destruction (__kmem_cache_destroy_memcg_children). Currently we just don't bother about it. This patch simplifies it by substituting per memcg slab_caches_mutex's with the global memcg_slab_mutex. It will be held whenever a new per memcg cache is created or destroyed, so it protects per root cache memcg_caches arrays and per memcg memcg_slab_caches lists. The locking order is following: activate_kmem_mutex -> memcg_slab_mutex -> slab_mutex This allows us to call kmem_cache_{create,shrink,destroy} under the memcg_slab_mutex. As a result, we don't need memcg_cache_params::destroy work any more - we can simply destroy caches while iterating over a per memcg slab caches list. Also using the global mutex simplifies synchronization between concurrent per memcg caches creation/destruction, e.g. mem_cgroup_destroy_all_caches vs __kmem_cache_destroy_memcg_children. The downside of this is that we substitute per-memcg slab_caches_mutex's with a hummer-like global mutex, but since we already take either the slab_mutex or the cgroup_mutex along with a memcg::slab_caches_mutex, it shouldn't hurt concurrency a lot. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@gmail.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:40 +00:00
struct kmem_cache *s = NULL;
char *cache_name;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
int idx;
get_online_cpus();
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
get_online_mems();
mutex_lock(&slab_mutex);
/*
* The memory cgroup could have been offlined while the cache
* creation work was pending.
*/
if (memcg->kmem_state != KMEM_ONLINE)
goto out_unlock;
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
idx = memcg_cache_id(memcg);
arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
/*
* Since per-memcg caches are created asynchronously on first
* allocation (see memcg_kmem_get_cache()), several threads can try to
* create the same cache, but only one of them may succeed.
*/
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
if (arr->entries[idx])
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
goto out_unlock;
cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
mm: memcontrol: fix cgroup creation failure after many small jobs The memory controller has quite a bit of state that usually outlives the cgroup and pins its CSS until said state disappears. At the same time it imposes a 16-bit limit on the CSS ID space to economically store IDs in the wild. Consequently, when we use cgroups to contain frequent but small and short-lived jobs that leave behind some page cache, we quickly run into the 64k limitations of outstanding CSSs. Creating a new cgroup fails with -ENOSPC while there are only a few, or even no user-visible cgroups in existence. Although pinning CSSs past cgroup removal is common, there are only two instances that actually need an ID after a cgroup is deleted: cache shadow entries and swapout records. Cache shadow entries reference the ID weakly and can deal with the CSS having disappeared when it's looked up later. They pose no hurdle. Swap-out records do need to pin the css to hierarchically attribute swapins after the cgroup has been deleted; though the only pages that remain swapped out after offlining are tmpfs/shmem pages. And those references are under the user's control, so they are manageable. This patch introduces a private 16-bit memcg ID and switches swap and cache shadow entries over to using that. This ID can then be recycled after offlining when the CSS remains pinned only by objects that don't specifically need it. This script demonstrates the problem by faulting one cache page in a new cgroup and deleting it again: set -e mkdir -p pages for x in `seq 128000`; do [ $((x % 1000)) -eq 0 ] && echo $x mkdir /cgroup/foo echo $$ >/cgroup/foo/cgroup.procs echo trex >pages/$x echo $$ >/cgroup/cgroup.procs rmdir /cgroup/foo done When run on an unpatched kernel, we eventually run out of possible IDs even though there are no visible cgroups: [root@ham ~]# ./cssidstress.sh [...] 65000 mkdir: cannot create directory '/cgroup/foo': No space left on device After this patch, the IDs get released upon cgroup destruction and the cache and css objects get released once memory reclaim kicks in. [hannes@cmpxchg.org: init the IDR] Link: http://lkml.kernel.org/r/20160621154601.GA22431@cmpxchg.org Fixes: b2052564e66d ("mm: memcontrol: continue cache reclaim from offlined groups") Link: http://lkml.kernel.org/r/20160617162516.GD19084@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: John Garcia <john.garcia@mesosphere.io> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Nikolay Borisov <kernel@kyup.com> Cc: <stable@vger.kernel.org> [3.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-20 22:44:57 +00:00
cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
css->serial_nr, memcg_name_buf);
if (!cache_name)
goto out_unlock;
s = create_cache(cache_name, root_cache->object_size,
root_cache->size, root_cache->align,
memcg: prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB While testing OBJFREELIST_SLAB integration with pagealloc, we found a bug where kmem_cache(sys) would be created with both CFLGS_OFF_SLAB & CFLGS_OBJFREELIST_SLAB. When it happened, critical allocations needed for loading drivers or creating new caches will fail. The original kmem_cache is created early making OFF_SLAB not possible. When kmem_cache(sys) is created, OFF_SLAB is possible and if pagealloc is enabled it will try to enable it first under certain conditions. Given kmem_cache(sys) reuses the original flag, you can have both flags at the same time resulting in allocation failures and odd behaviors. This fix discards allocator specific flags from memcg before calling create_cache. The bug exists since 4.6-rc1 and affects testing debug pagealloc configurations. Fixes: b03a017bebc4 ("mm/slab: introduce new slab management type, OBJFREELIST_SLAB") Link: http://lkml.kernel.org/r/1478553075-120242-1-git-send-email-thgarnie@google.com Signed-off-by: Greg Thelen <gthelen@google.com> Signed-off-by: Thomas Garnier <thgarnie@google.com> Tested-by: Thomas Garnier <thgarnie@google.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 18:46:41 +00:00
root_cache->flags & CACHE_CREATE_MASK,
root_cache->ctor, memcg, root_cache);
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
/*
* If we could not create a memcg cache, do not complain, because
* that's not critical at all as we can always proceed with the root
* cache.
*/
memcg, slab: simplify synchronization scheme At present, we have the following mutexes protecting data related to per memcg kmem caches: - slab_mutex. This one is held during the whole kmem cache creation and destruction paths. We also take it when updating per root cache memcg_caches arrays (see memcg_update_all_caches). As a result, taking it guarantees there will be no changes to any kmem cache (including per memcg). Why do we need something else then? The point is it is private to slab implementation and has some internal dependencies with other mutexes (get_online_cpus). So we just don't want to rely upon it and prefer to introduce additional mutexes instead. - activate_kmem_mutex. Initially it was added to synchronize initializing kmem limit (memcg_activate_kmem). However, since we can grow per root cache memcg_caches arrays only on kmem limit initialization (see memcg_update_all_caches), we also employ it to protect against memcg_caches arrays relocation (e.g. see __kmem_cache_destroy_memcg_children). - We have a convention not to take slab_mutex in memcontrol.c, but we want to walk over per memcg memcg_slab_caches lists there (e.g. for destroying all memcg caches on offline). So we have per memcg slab_caches_mutex's protecting those lists. The mutexes are taken in the following order: activate_kmem_mutex -> slab_mutex -> memcg::slab_caches_mutex Such a syncrhonization scheme has a number of flaws, for instance: - We can't call kmem_cache_{destroy,shrink} while walking over a memcg::memcg_slab_caches list due to locking order. As a result, in mem_cgroup_destroy_all_caches we schedule the memcg_cache_params::destroy work shrinking and destroying the cache. - We don't have a mutex to synchronize per memcg caches destruction between memcg offline (mem_cgroup_destroy_all_caches) and root cache destruction (__kmem_cache_destroy_memcg_children). Currently we just don't bother about it. This patch simplifies it by substituting per memcg slab_caches_mutex's with the global memcg_slab_mutex. It will be held whenever a new per memcg cache is created or destroyed, so it protects per root cache memcg_caches arrays and per memcg memcg_slab_caches lists. The locking order is following: activate_kmem_mutex -> memcg_slab_mutex -> slab_mutex This allows us to call kmem_cache_{create,shrink,destroy} under the memcg_slab_mutex. As a result, we don't need memcg_cache_params::destroy work any more - we can simply destroy caches while iterating over a per memcg slab caches list. Also using the global mutex simplifies synchronization between concurrent per memcg caches creation/destruction, e.g. mem_cgroup_destroy_all_caches vs __kmem_cache_destroy_memcg_children. The downside of this is that we substitute per-memcg slab_caches_mutex's with a hummer-like global mutex, but since we already take either the slab_mutex or the cgroup_mutex along with a memcg::slab_caches_mutex, it shouldn't hurt concurrency a lot. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@gmail.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:40 +00:00
if (IS_ERR(s)) {
kfree(cache_name);
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
goto out_unlock;
memcg, slab: simplify synchronization scheme At present, we have the following mutexes protecting data related to per memcg kmem caches: - slab_mutex. This one is held during the whole kmem cache creation and destruction paths. We also take it when updating per root cache memcg_caches arrays (see memcg_update_all_caches). As a result, taking it guarantees there will be no changes to any kmem cache (including per memcg). Why do we need something else then? The point is it is private to slab implementation and has some internal dependencies with other mutexes (get_online_cpus). So we just don't want to rely upon it and prefer to introduce additional mutexes instead. - activate_kmem_mutex. Initially it was added to synchronize initializing kmem limit (memcg_activate_kmem). However, since we can grow per root cache memcg_caches arrays only on kmem limit initialization (see memcg_update_all_caches), we also employ it to protect against memcg_caches arrays relocation (e.g. see __kmem_cache_destroy_memcg_children). - We have a convention not to take slab_mutex in memcontrol.c, but we want to walk over per memcg memcg_slab_caches lists there (e.g. for destroying all memcg caches on offline). So we have per memcg slab_caches_mutex's protecting those lists. The mutexes are taken in the following order: activate_kmem_mutex -> slab_mutex -> memcg::slab_caches_mutex Such a syncrhonization scheme has a number of flaws, for instance: - We can't call kmem_cache_{destroy,shrink} while walking over a memcg::memcg_slab_caches list due to locking order. As a result, in mem_cgroup_destroy_all_caches we schedule the memcg_cache_params::destroy work shrinking and destroying the cache. - We don't have a mutex to synchronize per memcg caches destruction between memcg offline (mem_cgroup_destroy_all_caches) and root cache destruction (__kmem_cache_destroy_memcg_children). Currently we just don't bother about it. This patch simplifies it by substituting per memcg slab_caches_mutex's with the global memcg_slab_mutex. It will be held whenever a new per memcg cache is created or destroyed, so it protects per root cache memcg_caches arrays and per memcg memcg_slab_caches lists. The locking order is following: activate_kmem_mutex -> memcg_slab_mutex -> slab_mutex This allows us to call kmem_cache_{create,shrink,destroy} under the memcg_slab_mutex. As a result, we don't need memcg_cache_params::destroy work any more - we can simply destroy caches while iterating over a per memcg slab caches list. Also using the global mutex simplifies synchronization between concurrent per memcg caches creation/destruction, e.g. mem_cgroup_destroy_all_caches vs __kmem_cache_destroy_memcg_children. The downside of this is that we substitute per-memcg slab_caches_mutex's with a hummer-like global mutex, but since we already take either the slab_mutex or the cgroup_mutex along with a memcg::slab_caches_mutex, it shouldn't hurt concurrency a lot. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@gmail.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:40 +00:00
}
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
/*
* Since readers won't lock (see cache_from_memcg_idx()), we need a
* barrier here to ensure nobody will see the kmem_cache partially
* initialized.
*/
smp_wmb();
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
arr->entries[idx] = s;
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
out_unlock:
mutex_unlock(&slab_mutex);
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
put_online_mems();
put_online_cpus();
}
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
slab: remove synchronous synchronize_sched() from memcg cache deactivation path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slub uses synchronize_sched() to deactivate a memcg cache. synchronize_sched() is an expensive and slow operation and doesn't scale when a huge number of caches are destroyed back-to-back. While there used to be a simple batching mechanism, the batching was too restricted to be helpful. This patch implements slab_deactivate_memcg_cache_rcu_sched() which slub can use to schedule sched RCU callback instead of performing synchronize_sched() synchronously while holding cgroup_mutex. While this adds online cpus, mems and slab_mutex operations, operating on these locks back-to-back from the same kworker, which is what's gonna happen when there are many to deactivate, isn't expensive at all and this gets rid of the scalability problem completely. Link: http://lkml.kernel.org/r/20170117235411.9408-9-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:30 +00:00
static void kmemcg_deactivate_workfn(struct work_struct *work)
{
struct kmem_cache *s = container_of(work, struct kmem_cache,
memcg_params.deact_work);
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
s->memcg_params.deact_fn(s);
mutex_unlock(&slab_mutex);
put_online_mems();
put_online_cpus();
/* done, put the ref from slab_deactivate_memcg_cache_rcu_sched() */
css_put(&s->memcg_params.memcg->css);
}
static void kmemcg_deactivate_rcufn(struct rcu_head *head)
{
struct kmem_cache *s = container_of(head, struct kmem_cache,
memcg_params.deact_rcu_head);
/*
* We need to grab blocking locks. Bounce to ->deact_work. The
* work item shares the space with the RCU head and can't be
* initialized eariler.
*/
INIT_WORK(&s->memcg_params.deact_work, kmemcg_deactivate_workfn);
queue_work(memcg_kmem_cache_wq, &s->memcg_params.deact_work);
slab: remove synchronous synchronize_sched() from memcg cache deactivation path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slub uses synchronize_sched() to deactivate a memcg cache. synchronize_sched() is an expensive and slow operation and doesn't scale when a huge number of caches are destroyed back-to-back. While there used to be a simple batching mechanism, the batching was too restricted to be helpful. This patch implements slab_deactivate_memcg_cache_rcu_sched() which slub can use to schedule sched RCU callback instead of performing synchronize_sched() synchronously while holding cgroup_mutex. While this adds online cpus, mems and slab_mutex operations, operating on these locks back-to-back from the same kworker, which is what's gonna happen when there are many to deactivate, isn't expensive at all and this gets rid of the scalability problem completely. Link: http://lkml.kernel.org/r/20170117235411.9408-9-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:30 +00:00
}
/**
* slab_deactivate_memcg_cache_rcu_sched - schedule deactivation after a
* sched RCU grace period
* @s: target kmem_cache
* @deact_fn: deactivation function to call
*
* Schedule @deact_fn to be invoked with online cpus, mems and slab_mutex
* held after a sched RCU grace period. The slab is guaranteed to stay
* alive until @deact_fn is finished. This is to be used from
* __kmemcg_cache_deactivate().
*/
void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s,
void (*deact_fn)(struct kmem_cache *))
{
if (WARN_ON_ONCE(is_root_cache(s)) ||
WARN_ON_ONCE(s->memcg_params.deact_fn))
return;
/* pin memcg so that @s doesn't get destroyed in the middle */
css_get(&s->memcg_params.memcg->css);
s->memcg_params.deact_fn = deact_fn;
call_rcu_sched(&s->memcg_params.deact_rcu_head, kmemcg_deactivate_rcufn);
}
void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
{
int idx;
struct memcg_cache_array *arr;
slub: make dead caches discard free slabs immediately To speed up further allocations SLUB may store empty slabs in per cpu/node partial lists instead of freeing them immediately. This prevents per memcg caches destruction, because kmem caches created for a memory cgroup are only destroyed after the last page charged to the cgroup is freed. To fix this issue, this patch resurrects approach first proposed in [1]. It forbids SLUB to cache empty slabs after the memory cgroup that the cache belongs to was destroyed. It is achieved by setting kmem_cache's cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so that it would drop frozen empty slabs immediately if cpu_partial = 0. The runtime overhead is minimal. From all the hot functions, we only touch relatively cold put_cpu_partial(): we make it call unfreeze_partials() after freezing a slab that belongs to an offline memory cgroup. Since slab freezing exists to avoid moving slabs from/to a partial list on free/alloc, and there can't be allocations from dead caches, it shouldn't cause any overhead. We do have to disable preemption for put_cpu_partial() to achieve that though. The original patch was accepted well and even merged to the mm tree. However, I decided to withdraw it due to changes happening to the memcg core at that time. I had an idea of introducing per-memcg shrinkers for kmem caches, but now, as memcg has finally settled down, I do not see it as an option, because SLUB shrinker would be too costly to call since SLUB does not keep free slabs on a separate list. Besides, we currently do not even call per-memcg shrinkers for offline memcgs. Overall, it would introduce much more complexity to both SLUB and memcg than this small patch. Regarding to SLAB, there's no problem with it, because it shrinks per-cpu/node caches periodically. Thanks to list_lru reparenting, we no longer keep entries for offline cgroups in per-memcg arrays (such as memcg_cache_params->memcg_caches), so we do not have to bother if a per-memcg cache will be shrunk a bit later than it could be. [1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650 Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:47 +00:00
struct kmem_cache *s, *c;
idx = memcg_cache_id(memcg);
slub: make dead caches discard free slabs immediately To speed up further allocations SLUB may store empty slabs in per cpu/node partial lists instead of freeing them immediately. This prevents per memcg caches destruction, because kmem caches created for a memory cgroup are only destroyed after the last page charged to the cgroup is freed. To fix this issue, this patch resurrects approach first proposed in [1]. It forbids SLUB to cache empty slabs after the memory cgroup that the cache belongs to was destroyed. It is achieved by setting kmem_cache's cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so that it would drop frozen empty slabs immediately if cpu_partial = 0. The runtime overhead is minimal. From all the hot functions, we only touch relatively cold put_cpu_partial(): we make it call unfreeze_partials() after freezing a slab that belongs to an offline memory cgroup. Since slab freezing exists to avoid moving slabs from/to a partial list on free/alloc, and there can't be allocations from dead caches, it shouldn't cause any overhead. We do have to disable preemption for put_cpu_partial() to achieve that though. The original patch was accepted well and even merged to the mm tree. However, I decided to withdraw it due to changes happening to the memcg core at that time. I had an idea of introducing per-memcg shrinkers for kmem caches, but now, as memcg has finally settled down, I do not see it as an option, because SLUB shrinker would be too costly to call since SLUB does not keep free slabs on a separate list. Besides, we currently do not even call per-memcg shrinkers for offline memcgs. Overall, it would introduce much more complexity to both SLUB and memcg than this small patch. Regarding to SLAB, there's no problem with it, because it shrinks per-cpu/node caches periodically. Thanks to list_lru reparenting, we no longer keep entries for offline cgroups in per-memcg arrays (such as memcg_cache_params->memcg_caches), so we do not have to bother if a per-memcg cache will be shrunk a bit later than it could be. [1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650 Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:47 +00:00
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
list_for_each_entry(s, &slab_root_caches, root_caches_node) {
arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
slub: make dead caches discard free slabs immediately To speed up further allocations SLUB may store empty slabs in per cpu/node partial lists instead of freeing them immediately. This prevents per memcg caches destruction, because kmem caches created for a memory cgroup are only destroyed after the last page charged to the cgroup is freed. To fix this issue, this patch resurrects approach first proposed in [1]. It forbids SLUB to cache empty slabs after the memory cgroup that the cache belongs to was destroyed. It is achieved by setting kmem_cache's cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so that it would drop frozen empty slabs immediately if cpu_partial = 0. The runtime overhead is minimal. From all the hot functions, we only touch relatively cold put_cpu_partial(): we make it call unfreeze_partials() after freezing a slab that belongs to an offline memory cgroup. Since slab freezing exists to avoid moving slabs from/to a partial list on free/alloc, and there can't be allocations from dead caches, it shouldn't cause any overhead. We do have to disable preemption for put_cpu_partial() to achieve that though. The original patch was accepted well and even merged to the mm tree. However, I decided to withdraw it due to changes happening to the memcg core at that time. I had an idea of introducing per-memcg shrinkers for kmem caches, but now, as memcg has finally settled down, I do not see it as an option, because SLUB shrinker would be too costly to call since SLUB does not keep free slabs on a separate list. Besides, we currently do not even call per-memcg shrinkers for offline memcgs. Overall, it would introduce much more complexity to both SLUB and memcg than this small patch. Regarding to SLAB, there's no problem with it, because it shrinks per-cpu/node caches periodically. Thanks to list_lru reparenting, we no longer keep entries for offline cgroups in per-memcg arrays (such as memcg_cache_params->memcg_caches), so we do not have to bother if a per-memcg cache will be shrunk a bit later than it could be. [1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650 Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:47 +00:00
c = arr->entries[idx];
if (!c)
continue;
__kmemcg_cache_deactivate(c);
arr->entries[idx] = NULL;
}
mutex_unlock(&slab_mutex);
slub: make dead caches discard free slabs immediately To speed up further allocations SLUB may store empty slabs in per cpu/node partial lists instead of freeing them immediately. This prevents per memcg caches destruction, because kmem caches created for a memory cgroup are only destroyed after the last page charged to the cgroup is freed. To fix this issue, this patch resurrects approach first proposed in [1]. It forbids SLUB to cache empty slabs after the memory cgroup that the cache belongs to was destroyed. It is achieved by setting kmem_cache's cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so that it would drop frozen empty slabs immediately if cpu_partial = 0. The runtime overhead is minimal. From all the hot functions, we only touch relatively cold put_cpu_partial(): we make it call unfreeze_partials() after freezing a slab that belongs to an offline memory cgroup. Since slab freezing exists to avoid moving slabs from/to a partial list on free/alloc, and there can't be allocations from dead caches, it shouldn't cause any overhead. We do have to disable preemption for put_cpu_partial() to achieve that though. The original patch was accepted well and even merged to the mm tree. However, I decided to withdraw it due to changes happening to the memcg core at that time. I had an idea of introducing per-memcg shrinkers for kmem caches, but now, as memcg has finally settled down, I do not see it as an option, because SLUB shrinker would be too costly to call since SLUB does not keep free slabs on a separate list. Besides, we currently do not even call per-memcg shrinkers for offline memcgs. Overall, it would introduce much more complexity to both SLUB and memcg than this small patch. Regarding to SLAB, there's no problem with it, because it shrinks per-cpu/node caches periodically. Thanks to list_lru reparenting, we no longer keep entries for offline cgroups in per-memcg arrays (such as memcg_cache_params->memcg_caches), so we do not have to bother if a per-memcg cache will be shrunk a bit later than it could be. [1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650 Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:47 +00:00
put_online_mems();
put_online_cpus();
}
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
{
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
struct kmem_cache *s, *s2;
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
get_online_cpus();
get_online_mems();
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
mutex_lock(&slab_mutex);
slab: link memcg kmem_caches on their associated memory cgroup With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. While a memcg kmem_cache is listed on its root cache's ->children list, there is no direct way to iterate all kmem_caches which are assocaited with a memory cgroup. The only way to iterate them is walking all caches while filtering out caches which don't match, which would be most of them. This makes memcg destruction operations O(N^2) where N is the total number of slab caches which can be huge. This combined with the synchronous RCU operations can tie up a CPU and affect the whole machine for many hours when memory reclaim triggers offlining and destruction of the stale memcgs. This patch adds mem_cgroup->kmem_caches list which goes through memcg_cache_params->kmem_caches_node of all kmem_caches which are associated with the memcg. All memcg specific iterations, including stat file access, are updated to use the new list instead. Link: http://lkml.kernel.org/r/20170117235411.9408-6-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:21 +00:00
list_for_each_entry_safe(s, s2, &memcg->kmem_caches,
memcg_params.kmem_caches_node) {
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
/*
* The cgroup is about to be freed and therefore has no charges
* left. Hence, all its caches must be empty by now.
*/
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
BUG_ON(shutdown_cache(s));
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
}
mutex_unlock(&slab_mutex);
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
put_online_mems();
put_online_cpus();
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
}
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
static int shutdown_memcg_caches(struct kmem_cache *s)
{
struct memcg_cache_array *arr;
struct kmem_cache *c, *c2;
LIST_HEAD(busy);
int i;
BUG_ON(!is_root_cache(s));
/*
* First, shutdown active caches, i.e. caches that belong to online
* memory cgroups.
*/
arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
for_each_memcg_cache_index(i) {
c = arr->entries[i];
if (!c)
continue;
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
if (shutdown_cache(c))
/*
* The cache still has objects. Move it to a temporary
* list so as not to try to destroy it for a second
* time while iterating over inactive caches below.
*/
list_move(&c->memcg_params.children_node, &busy);
else
/*
* The cache is empty and will be destroyed soon. Clear
* the pointer to it in the memcg_caches array so that
* it will never be accessed even if the root cache
* stays alive.
*/
arr->entries[i] = NULL;
}
/*
* Second, shutdown all caches left from memory cgroups that are now
* offline.
*/
list_for_each_entry_safe(c, c2, &s->memcg_params.children,
memcg_params.children_node)
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
shutdown_cache(c);
list_splice(&busy, &s->memcg_params.children);
/*
* A cache being destroyed must be empty. In particular, this means
* that all per memcg caches attached to it must be empty too.
*/
if (!list_empty(&s->memcg_params.children))
return -EBUSY;
return 0;
}
#else
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
static inline int shutdown_memcg_caches(struct kmem_cache *s)
{
return 0;
}
#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
slub: use sysfs'es release mechanism for kmem_cache debugobjects warning during netfilter exit: ------------[ cut here ]------------ WARNING: CPU: 6 PID: 4178 at lib/debugobjects.c:260 debug_print_object+0x8d/0xb0() ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20 Modules linked in: CPU: 6 PID: 4178 Comm: kworker/u16:2 Tainted: G W 3.11.0-next-20130906-sasha #3984 Workqueue: netns cleanup_net Call Trace: dump_stack+0x52/0x87 warn_slowpath_common+0x8c/0xc0 warn_slowpath_fmt+0x46/0x50 debug_print_object+0x8d/0xb0 __debug_check_no_obj_freed+0xa5/0x220 debug_check_no_obj_freed+0x15/0x20 kmem_cache_free+0x197/0x340 kmem_cache_destroy+0x86/0xe0 nf_conntrack_cleanup_net_list+0x131/0x170 nf_conntrack_pernet_exit+0x5d/0x70 ops_exit_list+0x5e/0x70 cleanup_net+0xfb/0x1c0 process_one_work+0x338/0x550 worker_thread+0x215/0x350 kthread+0xe7/0xf0 ret_from_fork+0x7c/0xb0 Also during dcookie cleanup: WARNING: CPU: 12 PID: 9725 at lib/debugobjects.c:260 debug_print_object+0x8c/0xb0() ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20 Modules linked in: CPU: 12 PID: 9725 Comm: trinity-c141 Not tainted 3.15.0-rc2-next-20140423-sasha-00018-gc4ff6c4 #408 Call Trace: dump_stack (lib/dump_stack.c:52) warn_slowpath_common (kernel/panic.c:430) warn_slowpath_fmt (kernel/panic.c:445) debug_print_object (lib/debugobjects.c:262) __debug_check_no_obj_freed (lib/debugobjects.c:697) debug_check_no_obj_freed (lib/debugobjects.c:726) kmem_cache_free (mm/slub.c:2689 mm/slub.c:2717) kmem_cache_destroy (mm/slab_common.c:363) dcookie_unregister (fs/dcookies.c:302 fs/dcookies.c:343) event_buffer_release (arch/x86/oprofile/../../../drivers/oprofile/event_buffer.c:153) __fput (fs/file_table.c:217) ____fput (fs/file_table.c:253) task_work_run (kernel/task_work.c:125 (discriminator 1)) do_notify_resume (include/linux/tracehook.h:196 arch/x86/kernel/signal.c:751) int_signal (arch/x86/kernel/entry_64.S:807) Sysfs has a release mechanism. Use that to release the kmem_cache structure if CONFIG_SYSFS is enabled. Only slub is changed - slab currently only supports /proc/slabinfo and not /sys/kernel/slab/*. We talked about adding that and someone was working on it. [akpm@linux-foundation.org: fix CONFIG_SYSFS=n build] [akpm@linux-foundation.org: fix CONFIG_SYSFS=n build even more] Signed-off-by: Christoph Lameter <cl@linux.com> Reported-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Acked-by: Greg KH <greg@kroah.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Pekka Enberg <penberg@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 19:50:08 +00:00
void slab_kmem_cache_release(struct kmem_cache *s)
{
mm: slab: free kmem_cache_node after destroy sysfs file When slub_debug alloc_calls_show is enabled we will try to track location and user of slab object on each online node, kmem_cache_node structure and cpu_cache/cpu_slub shouldn't be freed till there is the last reference to sysfs file. This fixes the following panic: BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 IP: list_locations+0x169/0x4e0 PGD 257304067 PUD 438456067 PMD 0 Oops: 0000 [#1] SMP CPU: 3 PID: 973074 Comm: cat ve: 0 Not tainted 3.10.0-229.7.2.ovz.9.30-00007-japdoll-dirty #2 9.30 Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c 07/14/2011 task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000 RIP: list_locations+0x169/0x4e0 Call Trace: alloc_calls_show+0x1d/0x30 slab_attr_show+0x1b/0x30 sysfs_read_file+0x9a/0x1a0 vfs_read+0x9c/0x170 SyS_read+0x58/0xb0 system_call_fastpath+0x16/0x1b Code: 5e 07 12 00 b9 00 04 00 00 3d 00 04 00 00 0f 4f c1 3d 00 04 00 00 89 45 b0 0f 84 c3 00 00 00 48 63 45 b0 49 8b 9c c4 f8 00 00 00 <48> 8b 43 20 48 85 c0 74 b6 48 89 df e8 46 37 44 00 48 8b 53 10 CR2: 0000000000000020 Separated __kmem_cache_release from __kmem_cache_shutdown which now called on slab_kmem_cache_release (after the last reference to sysfs file object has dropped). Reintroduced locking in free_partial as sysfs file might access cache's partial list after shutdowning - partial revert of the commit 69cb8e6b7c29 ("slub: free slabs without holding locks"). Zap __remove_partial and use remove_partial (w/o underscores) as free_partial now takes list_lock which s partial revert for commit 1e4dd9461fab ("slub: do not assert not having lock in removing freed partial") Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-17 21:11:37 +00:00
__kmem_cache_release(s);
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
destroy_memcg_params(s);
kfree_const(s->name);
slub: use sysfs'es release mechanism for kmem_cache debugobjects warning during netfilter exit: ------------[ cut here ]------------ WARNING: CPU: 6 PID: 4178 at lib/debugobjects.c:260 debug_print_object+0x8d/0xb0() ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20 Modules linked in: CPU: 6 PID: 4178 Comm: kworker/u16:2 Tainted: G W 3.11.0-next-20130906-sasha #3984 Workqueue: netns cleanup_net Call Trace: dump_stack+0x52/0x87 warn_slowpath_common+0x8c/0xc0 warn_slowpath_fmt+0x46/0x50 debug_print_object+0x8d/0xb0 __debug_check_no_obj_freed+0xa5/0x220 debug_check_no_obj_freed+0x15/0x20 kmem_cache_free+0x197/0x340 kmem_cache_destroy+0x86/0xe0 nf_conntrack_cleanup_net_list+0x131/0x170 nf_conntrack_pernet_exit+0x5d/0x70 ops_exit_list+0x5e/0x70 cleanup_net+0xfb/0x1c0 process_one_work+0x338/0x550 worker_thread+0x215/0x350 kthread+0xe7/0xf0 ret_from_fork+0x7c/0xb0 Also during dcookie cleanup: WARNING: CPU: 12 PID: 9725 at lib/debugobjects.c:260 debug_print_object+0x8c/0xb0() ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20 Modules linked in: CPU: 12 PID: 9725 Comm: trinity-c141 Not tainted 3.15.0-rc2-next-20140423-sasha-00018-gc4ff6c4 #408 Call Trace: dump_stack (lib/dump_stack.c:52) warn_slowpath_common (kernel/panic.c:430) warn_slowpath_fmt (kernel/panic.c:445) debug_print_object (lib/debugobjects.c:262) __debug_check_no_obj_freed (lib/debugobjects.c:697) debug_check_no_obj_freed (lib/debugobjects.c:726) kmem_cache_free (mm/slub.c:2689 mm/slub.c:2717) kmem_cache_destroy (mm/slab_common.c:363) dcookie_unregister (fs/dcookies.c:302 fs/dcookies.c:343) event_buffer_release (arch/x86/oprofile/../../../drivers/oprofile/event_buffer.c:153) __fput (fs/file_table.c:217) ____fput (fs/file_table.c:253) task_work_run (kernel/task_work.c:125 (discriminator 1)) do_notify_resume (include/linux/tracehook.h:196 arch/x86/kernel/signal.c:751) int_signal (arch/x86/kernel/entry_64.S:807) Sysfs has a release mechanism. Use that to release the kmem_cache structure if CONFIG_SYSFS is enabled. Only slub is changed - slab currently only supports /proc/slabinfo and not /sys/kernel/slab/*. We talked about adding that and someone was working on it. [akpm@linux-foundation.org: fix CONFIG_SYSFS=n build] [akpm@linux-foundation.org: fix CONFIG_SYSFS=n build even more] Signed-off-by: Christoph Lameter <cl@linux.com> Reported-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Acked-by: Greg KH <greg@kroah.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Pekka Enberg <penberg@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 19:50:08 +00:00
kmem_cache_free(kmem_cache, s);
}
void kmem_cache_destroy(struct kmem_cache *s)
{
int err;
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
if (unlikely(!s))
return;
get_online_cpus();
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
get_online_mems();
mutex_lock(&slab_mutex);
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
s->refcount--;
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
if (s->refcount)
goto out_unlock;
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
err = shutdown_memcg_caches(s);
if (!err)
slab: remove synchronous rcu_barrier() call in memcg cache release path With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. SLAB_DESTORY_BY_RCU caches need to flush all RCU operations before destruction because slab pages are freed through RCU and they need to be able to dereference the associated kmem_cache. Currently, it's done synchronously with rcu_barrier(). As rcu_barrier() is expensive time-wise, slab implements a batching mechanism so that rcu_barrier() can be done for multiple caches at the same time. Unfortunately, the rcu_barrier() is in synchronous path which is called while holding cgroup_mutex and the batching is too limited to be actually helpful. This patch updates the cache release path so that the batching is asynchronous and global. All SLAB_DESTORY_BY_RCU caches are queued globally and a work item consumes the list. The work item calls rcu_barrier() only once for all caches that are currently queued. * release_caches() is removed and shutdown_cache() now either directly release the cache or schedules a RCU callback to do that. This makes the cache inaccessible once shutdown_cache() is called and makes it impossible for shutdown_memcg_caches() to do memcg-specific cleanups afterwards. Move memcg-specific part into a helper, unlink_memcg_cache(), and make shutdown_cache() call it directly. Link: http://lkml.kernel.org/r/20170117235411.9408-4-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:14 +00:00
err = shutdown_cache(s);
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
if (err) {
pr_err("kmem_cache_destroy %s: Slab cache still has objects\n",
s->name);
dump_stack();
}
memcg, slab: do not destroy children caches if parent has aliases Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 22:39:28 +00:00
out_unlock:
mutex_unlock(&slab_mutex);
memcg: zap memcg_slab_caches and memcg_slab_mutex mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 22:11:47 +00:00
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
put_online_mems();
put_online_cpus();
}
EXPORT_SYMBOL(kmem_cache_destroy);
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
/**
* kmem_cache_shrink - Shrink a cache.
* @cachep: The cache to shrink.
*
* Releases as many slabs as possible for a cache.
* To help debugging, a zero exit status indicates all slabs were released.
*/
int kmem_cache_shrink(struct kmem_cache *cachep)
{
int ret;
get_online_cpus();
get_online_mems();
mm: kasan: initial memory quarantine implementation Quarantine isolates freed objects in a separate queue. The objects are returned to the allocator later, which helps to detect use-after-free errors. When the object is freed, its state changes from KASAN_STATE_ALLOC to KASAN_STATE_QUARANTINE. The object is poisoned and put into quarantine instead of being returned to the allocator, therefore every subsequent access to that object triggers a KASAN error, and the error handler is able to say where the object has been allocated and deallocated. When it's time for the object to leave quarantine, its state becomes KASAN_STATE_FREE and it's returned to the allocator. From now on the allocator may reuse it for another allocation. Before that happens, it's still possible to detect a use-after free on that object (it retains the allocation/deallocation stacks). When the allocator reuses this object, the shadow is unpoisoned and old allocation/deallocation stacks are wiped. Therefore a use of this object, even an incorrect one, won't trigger ASan warning. Without the quarantine, it's not guaranteed that the objects aren't reused immediately, that's why the probability of catching a use-after-free is lower than with quarantine in place. Quarantine isolates freed objects in a separate queue. The objects are returned to the allocator later, which helps to detect use-after-free errors. Freed objects are first added to per-cpu quarantine queues. When a cache is destroyed or memory shrinking is requested, the objects are moved into the global quarantine queue. Whenever a kmalloc call allows memory reclaiming, the oldest objects are popped out of the global queue until the total size of objects in quarantine is less than 3/4 of the maximum quarantine size (which is a fraction of installed physical memory). As long as an object remains in the quarantine, KASAN is able to report accesses to it, so the chance of reporting a use-after-free is increased. Once the object leaves quarantine, the allocator may reuse it, in which case the object is unpoisoned and KASAN can't detect incorrect accesses to it. Right now quarantine support is only enabled in SLAB allocator. Unification of KASAN features in SLAB and SLUB will be done later. This patch is based on the "mm: kasan: quarantine" patch originally prepared by Dmitry Chernenkov. A number of improvements have been suggested by Andrey Ryabinin. [glider@google.com: v9] Link: http://lkml.kernel.org/r/1462987130-144092-1-git-send-email-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrey Konovalov <adech.fo@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 23:59:11 +00:00
kasan_cache_shrink(cachep);
ret = __kmem_cache_shrink(cachep);
slab: get_online_mems for kmem_cache_{create,destroy,shrink} When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 23:07:20 +00:00
put_online_mems();
put_online_cpus();
return ret;
}
EXPORT_SYMBOL(kmem_cache_shrink);
bool slab_is_available(void)
{
return slab_state >= UP;
}
#ifndef CONFIG_SLOB
/* Create a cache during boot when no slab services are available yet */
void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
unsigned long flags)
{
int err;
s->name = name;
s->size = s->object_size = size;
s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
slab: embed memcg_cache_params to kmem_cache Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 22:59:20 +00:00
slab_init_memcg_params(s);
err = __kmem_cache_create(s, flags);
if (err)
panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
name, size, err);
s->refcount = -1; /* Exempt from merging for now */
}
struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
unsigned long flags)
{
struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
if (!s)
panic("Out of memory when creating slab %s\n", name);
create_boot_cache(s, name, size, flags);
list_add(&s->list, &slab_caches);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
memcg_link_cache(s);
s->refcount = 1;
return s;
}
struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
EXPORT_SYMBOL(kmalloc_caches);
#ifdef CONFIG_ZONE_DMA
struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
EXPORT_SYMBOL(kmalloc_dma_caches);
#endif
/*
* Conversion table for small slabs sizes / 8 to the index in the
* kmalloc array. This is necessary for slabs < 192 since we have non power
* of two cache sizes there. The size of larger slabs can be determined using
* fls.
*/
static s8 size_index[24] = {
3, /* 8 */
4, /* 16 */
5, /* 24 */
5, /* 32 */
6, /* 40 */
6, /* 48 */
6, /* 56 */
6, /* 64 */
1, /* 72 */
1, /* 80 */
1, /* 88 */
1, /* 96 */
7, /* 104 */
7, /* 112 */
7, /* 120 */
7, /* 128 */
2, /* 136 */
2, /* 144 */
2, /* 152 */
2, /* 160 */
2, /* 168 */
2, /* 176 */
2, /* 184 */
2 /* 192 */
};
static inline int size_index_elem(size_t bytes)
{
return (bytes - 1) / 8;
}
/*
* Find the kmem_cache structure that serves a given size of
* allocation
*/
struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
{
int index;
if (unlikely(size > KMALLOC_MAX_SIZE)) {
slab: prevent warnings when allocating with __GFP_NOWARN Sasha Levin noticed that the warning introduced by commit 6286ae9 ("slab: Return NULL for oversized allocations) is being triggered: WARNING: CPU: 15 PID: 21519 at mm/slab_common.c:376 kmalloc_slab+0x2f/0xb0() can: request_module (can-proto-4) failed. mpoa: proc_mpc_write: could not parse '' Modules linked in: CPU: 15 PID: 21519 Comm: trinity-child15 Tainted: G W 3.10.0-rc4-next-20130607-sasha-00011-gcd78395-dirty #2 0000000000000009 ffff880020a95e30 ffffffff83ff4041 0000000000000000 ffff880020a95e68 ffffffff8111fe12 fffffffffffffff0 00000000000082d0 0000000000080000 0000000000080000 0000000001400000 ffff880020a95e78 Call Trace: [<ffffffff83ff4041>] dump_stack+0x4e/0x82 [<ffffffff8111fe12>] warn_slowpath_common+0x82/0xb0 [<ffffffff8111fe55>] warn_slowpath_null+0x15/0x20 [<ffffffff81243dcf>] kmalloc_slab+0x2f/0xb0 [<ffffffff81278d54>] __kmalloc+0x24/0x4b0 [<ffffffff8196ffe3>] ? security_capable+0x13/0x20 [<ffffffff812a26b7>] ? pipe_fcntl+0x107/0x210 [<ffffffff812a26b7>] pipe_fcntl+0x107/0x210 [<ffffffff812b7ea0>] ? fget_raw_light+0x130/0x3f0 [<ffffffff812aa5fb>] SyS_fcntl+0x60b/0x6a0 [<ffffffff8403ca98>] tracesys+0xe1/0xe6 Andrew Morton writes: __GFP_NOWARN is frequently used by kernel code to probe for "how big an allocation can I get". That's a bit lame, but it's used on slow paths and is pretty simple. However, SLAB would still spew a warning when a big allocation happens if the __GFP_NOWARN flag is _not_ set to expose kernel bugs. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> [ penberg@kernel.org: improve changelog ] Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-06-10 19:18:00 +00:00
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
slab: prevent warnings when allocating with __GFP_NOWARN Sasha Levin noticed that the warning introduced by commit 6286ae9 ("slab: Return NULL for oversized allocations) is being triggered: WARNING: CPU: 15 PID: 21519 at mm/slab_common.c:376 kmalloc_slab+0x2f/0xb0() can: request_module (can-proto-4) failed. mpoa: proc_mpc_write: could not parse '' Modules linked in: CPU: 15 PID: 21519 Comm: trinity-child15 Tainted: G W 3.10.0-rc4-next-20130607-sasha-00011-gcd78395-dirty #2 0000000000000009 ffff880020a95e30 ffffffff83ff4041 0000000000000000 ffff880020a95e68 ffffffff8111fe12 fffffffffffffff0 00000000000082d0 0000000000080000 0000000000080000 0000000001400000 ffff880020a95e78 Call Trace: [<ffffffff83ff4041>] dump_stack+0x4e/0x82 [<ffffffff8111fe12>] warn_slowpath_common+0x82/0xb0 [<ffffffff8111fe55>] warn_slowpath_null+0x15/0x20 [<ffffffff81243dcf>] kmalloc_slab+0x2f/0xb0 [<ffffffff81278d54>] __kmalloc+0x24/0x4b0 [<ffffffff8196ffe3>] ? security_capable+0x13/0x20 [<ffffffff812a26b7>] ? pipe_fcntl+0x107/0x210 [<ffffffff812a26b7>] pipe_fcntl+0x107/0x210 [<ffffffff812b7ea0>] ? fget_raw_light+0x130/0x3f0 [<ffffffff812aa5fb>] SyS_fcntl+0x60b/0x6a0 [<ffffffff8403ca98>] tracesys+0xe1/0xe6 Andrew Morton writes: __GFP_NOWARN is frequently used by kernel code to probe for "how big an allocation can I get". That's a bit lame, but it's used on slow paths and is pretty simple. However, SLAB would still spew a warning when a big allocation happens if the __GFP_NOWARN flag is _not_ set to expose kernel bugs. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> [ penberg@kernel.org: improve changelog ] Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-06-10 19:18:00 +00:00
}
if (size <= 192) {
if (!size)
return ZERO_SIZE_PTR;
index = size_index[size_index_elem(size)];
} else
index = fls(size - 1);
#ifdef CONFIG_ZONE_DMA
if (unlikely((flags & GFP_DMA)))
return kmalloc_dma_caches[index];
#endif
return kmalloc_caches[index];
}
/*
* kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
* kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
* kmalloc-67108864.
*/
mm, slab: rename kmalloc-node cache to kmalloc-<size> SLAB as part of its bootstrap pre-creates one kmalloc cache that can fit the kmem_cache_node management structure, and puts it into the generic kmalloc cache array (e.g. for 128b objects). The name of this cache is "kmalloc-node", which is confusing for readers of /proc/slabinfo as the cache is used for generic allocations (and not just the kmem_cache_node struct) and it appears as the kmalloc-128 cache is missing. An easy solution is to use the kmalloc-<size> name when pre-creating the cache, which we can get from the kmalloc_info array. Example /proc/slabinfo before the patch: ... kmalloc-256 1647 1984 256 16 1 : tunables 120 60 8 : slabdata 124 124 828 kmalloc-192 1974 1974 192 21 1 : tunables 120 60 8 : slabdata 94 94 133 kmalloc-96 1332 1344 128 32 1 : tunables 120 60 8 : slabdata 42 42 219 kmalloc-64 2505 5952 64 64 1 : tunables 120 60 8 : slabdata 93 93 715 kmalloc-32 4278 4464 32 124 1 : tunables 120 60 8 : slabdata 36 36 346 kmalloc-node 1352 1376 128 32 1 : tunables 120 60 8 : slabdata 43 43 53 kmem_cache 132 147 192 21 1 : tunables 120 60 8 : slabdata 7 7 0 After the patch: ... kmalloc-256 1672 2160 256 16 1 : tunables 120 60 8 : slabdata 135 135 807 kmalloc-192 1992 2016 192 21 1 : tunables 120 60 8 : slabdata 96 96 203 kmalloc-96 1159 1184 128 32 1 : tunables 120 60 8 : slabdata 37 37 116 kmalloc-64 2561 4864 64 64 1 : tunables 120 60 8 : slabdata 76 76 785 kmalloc-32 4253 4340 32 124 1 : tunables 120 60 8 : slabdata 35 35 270 kmalloc-128 1256 1280 128 32 1 : tunables 120 60 8 : slabdata 40 40 39 kmem_cache 125 147 192 21 1 : tunables 120 60 8 : slabdata 7 7 0 [vbabka@suse.cz: export the whole kmalloc_info structure instead of just a name accessor, per Christoph Lameter] Link: http://lkml.kernel.org/r/54e80303-b814-4232-66d4-95b34d3eb9d0@suse.cz Link: http://lkml.kernel.org/r/20170203181008.24898-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:05 +00:00
const struct kmalloc_info_struct kmalloc_info[] __initconst = {
{NULL, 0}, {"kmalloc-96", 96},
{"kmalloc-192", 192}, {"kmalloc-8", 8},
{"kmalloc-16", 16}, {"kmalloc-32", 32},
{"kmalloc-64", 64}, {"kmalloc-128", 128},
{"kmalloc-256", 256}, {"kmalloc-512", 512},
{"kmalloc-1024", 1024}, {"kmalloc-2048", 2048},
{"kmalloc-4096", 4096}, {"kmalloc-8192", 8192},
{"kmalloc-16384", 16384}, {"kmalloc-32768", 32768},
{"kmalloc-65536", 65536}, {"kmalloc-131072", 131072},
{"kmalloc-262144", 262144}, {"kmalloc-524288", 524288},
{"kmalloc-1048576", 1048576}, {"kmalloc-2097152", 2097152},
{"kmalloc-4194304", 4194304}, {"kmalloc-8388608", 8388608},
{"kmalloc-16777216", 16777216}, {"kmalloc-33554432", 33554432},
{"kmalloc-67108864", 67108864}
};
/*
slab: correct size_index table before replacing the bootstrap kmem_cache_node This patch moves the initialization of the size_index table slightly earlier so that the first few kmem_cache_node's can be safely allocated when KMALLOC_MIN_SIZE is large. There are currently two ways to generate indices into kmalloc_caches (via kmalloc_index() and via the size_index table in slab_common.c) and on some arches (possibly only MIPS) they potentially disagree with each other until create_kmalloc_caches() has been called. It seems that the intention is that the size_index table is a fast equivalent to kmalloc_index() and that create_kmalloc_caches() patches the table to return the correct value for the cases where kmalloc_index()'s if-statements apply. The failing sequence was: * kmalloc_caches contains NULL elements * kmem_cache_init initialises the element that 'struct kmem_cache_node' will be allocated to. For 32-bit Mips, this is a 56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7). * init_list is called which calls kmalloc_node to allocate a 'struct kmem_cache_node'. * kmalloc_slab selects the kmem_caches element using size_index[size_index_elem(size)]. For MIPS, size is 56, and the expression returns 6. * This element of kmalloc_caches is NULL and allocation fails. * If it had not already failed, it would have called create_kmalloc_caches() at this point which would have changed size_index[size_index_elem(size)] to 7. I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things. Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 23:55:57 +00:00
* Patch up the size_index table if we have strange large alignment
* requirements for the kmalloc array. This is only the case for
* MIPS it seems. The standard arches will not generate any code here.
*
* Largest permitted alignment is 256 bytes due to the way we
* handle the index determination for the smaller caches.
*
* Make sure that nothing crazy happens if someone starts tinkering
* around with ARCH_KMALLOC_MINALIGN
*/
slab: correct size_index table before replacing the bootstrap kmem_cache_node This patch moves the initialization of the size_index table slightly earlier so that the first few kmem_cache_node's can be safely allocated when KMALLOC_MIN_SIZE is large. There are currently two ways to generate indices into kmalloc_caches (via kmalloc_index() and via the size_index table in slab_common.c) and on some arches (possibly only MIPS) they potentially disagree with each other until create_kmalloc_caches() has been called. It seems that the intention is that the size_index table is a fast equivalent to kmalloc_index() and that create_kmalloc_caches() patches the table to return the correct value for the cases where kmalloc_index()'s if-statements apply. The failing sequence was: * kmalloc_caches contains NULL elements * kmem_cache_init initialises the element that 'struct kmem_cache_node' will be allocated to. For 32-bit Mips, this is a 56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7). * init_list is called which calls kmalloc_node to allocate a 'struct kmem_cache_node'. * kmalloc_slab selects the kmem_caches element using size_index[size_index_elem(size)]. For MIPS, size is 56, and the expression returns 6. * This element of kmalloc_caches is NULL and allocation fails. * If it had not already failed, it would have called create_kmalloc_caches() at this point which would have changed size_index[size_index_elem(size)] to 7. I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things. Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 23:55:57 +00:00
void __init setup_kmalloc_cache_index_table(void)
{
int i;
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
int elem = size_index_elem(i);
if (elem >= ARRAY_SIZE(size_index))
break;
size_index[elem] = KMALLOC_SHIFT_LOW;
}
if (KMALLOC_MIN_SIZE >= 64) {
/*
* The 96 byte size cache is not used if the alignment
* is 64 byte.
*/
for (i = 64 + 8; i <= 96; i += 8)
size_index[size_index_elem(i)] = 7;
}
if (KMALLOC_MIN_SIZE >= 128) {
/*
* The 192 byte sized cache is not used if the alignment
* is 128 byte. Redirect kmalloc to use the 256 byte cache
* instead.
*/
for (i = 128 + 8; i <= 192; i += 8)
size_index[size_index_elem(i)] = 8;
}
slab: correct size_index table before replacing the bootstrap kmem_cache_node This patch moves the initialization of the size_index table slightly earlier so that the first few kmem_cache_node's can be safely allocated when KMALLOC_MIN_SIZE is large. There are currently two ways to generate indices into kmalloc_caches (via kmalloc_index() and via the size_index table in slab_common.c) and on some arches (possibly only MIPS) they potentially disagree with each other until create_kmalloc_caches() has been called. It seems that the intention is that the size_index table is a fast equivalent to kmalloc_index() and that create_kmalloc_caches() patches the table to return the correct value for the cases where kmalloc_index()'s if-statements apply. The failing sequence was: * kmalloc_caches contains NULL elements * kmem_cache_init initialises the element that 'struct kmem_cache_node' will be allocated to. For 32-bit Mips, this is a 56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7). * init_list is called which calls kmalloc_node to allocate a 'struct kmem_cache_node'. * kmalloc_slab selects the kmem_caches element using size_index[size_index_elem(size)]. For MIPS, size is 56, and the expression returns 6. * This element of kmalloc_caches is NULL and allocation fails. * If it had not already failed, it would have called create_kmalloc_caches() at this point which would have changed size_index[size_index_elem(size)] to 7. I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things. Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 23:55:57 +00:00
}
static void __init new_kmalloc_cache(int idx, unsigned long flags)
{
kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
kmalloc_info[idx].size, flags);
}
slab: correct size_index table before replacing the bootstrap kmem_cache_node This patch moves the initialization of the size_index table slightly earlier so that the first few kmem_cache_node's can be safely allocated when KMALLOC_MIN_SIZE is large. There are currently two ways to generate indices into kmalloc_caches (via kmalloc_index() and via the size_index table in slab_common.c) and on some arches (possibly only MIPS) they potentially disagree with each other until create_kmalloc_caches() has been called. It seems that the intention is that the size_index table is a fast equivalent to kmalloc_index() and that create_kmalloc_caches() patches the table to return the correct value for the cases where kmalloc_index()'s if-statements apply. The failing sequence was: * kmalloc_caches contains NULL elements * kmem_cache_init initialises the element that 'struct kmem_cache_node' will be allocated to. For 32-bit Mips, this is a 56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7). * init_list is called which calls kmalloc_node to allocate a 'struct kmem_cache_node'. * kmalloc_slab selects the kmem_caches element using size_index[size_index_elem(size)]. For MIPS, size is 56, and the expression returns 6. * This element of kmalloc_caches is NULL and allocation fails. * If it had not already failed, it would have called create_kmalloc_caches() at this point which would have changed size_index[size_index_elem(size)] to 7. I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things. Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 23:55:57 +00:00
/*
* Create the kmalloc array. Some of the regular kmalloc arrays
* may already have been created because they were needed to
* enable allocations for slab creation.
*/
void __init create_kmalloc_caches(unsigned long flags)
{
int i;
for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
if (!kmalloc_caches[i])
new_kmalloc_cache(i, flags);
/*
* Caches that are not of the two-to-the-power-of size.
* These have to be created immediately after the
* earlier power of two caches
*/
if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
new_kmalloc_cache(1, flags);
if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
new_kmalloc_cache(2, flags);
}
/* Kmalloc array is now usable */
slab_state = UP;
#ifdef CONFIG_ZONE_DMA
for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[i];
if (s) {
int size = kmalloc_size(i);
char *n = kasprintf(GFP_NOWAIT,
"dma-kmalloc-%d", size);
BUG_ON(!n);
kmalloc_dma_caches[i] = create_kmalloc_cache(n,
size, SLAB_CACHE_DMA | flags);
}
}
#endif
}
#endif /* !CONFIG_SLOB */
/*
* To avoid unnecessary overhead, we pass through large allocation requests
* directly to the page allocator. We use __GFP_COMP, because we will need to
* know the allocation order to free the pages properly in kfree.
*/
void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
{
void *ret;
struct page *page;
flags |= __GFP_COMP;
mm: charge/uncharge kmemcg from generic page allocator paths Currently, to charge a non-slab allocation to kmemcg one has to use alloc_kmem_pages helper with __GFP_ACCOUNT flag. A page allocated with this helper should finally be freed using free_kmem_pages, otherwise it won't be uncharged. This API suits its current users fine, but it turns out to be impossible to use along with page reference counting, i.e. when an allocation is supposed to be freed with put_page, as it is the case with pipe or unix socket buffers. To overcome this limitation, this patch moves charging/uncharging to generic page allocator paths, i.e. to __alloc_pages_nodemask and free_pages_prepare, and zaps alloc/free_kmem_pages helpers. This way, one can use any of the available page allocation functions to get the allocated page charged to kmemcg - it's enough to pass __GFP_ACCOUNT, just like in case of kmalloc and friends. A charged page will be automatically uncharged on free. To make it possible, we need to mark pages charged to kmemcg somehow. To avoid introducing a new page flag, we make use of page->_mapcount for marking such pages. Since pages charged to kmemcg are not supposed to be mapped to userspace, it should work just fine. There are other (ab)users of page->_mapcount - buddy and balloon pages - but we don't conflict with them. In case kmemcg is compiled out or not used at runtime, this patch introduces no overhead to generic page allocator paths. If kmemcg is used, it will be plus one gfp flags check on alloc and plus one page->_mapcount check on free, which shouldn't hurt performance, because the data accessed are hot. Link: http://lkml.kernel.org/r/a9736d856f895bcb465d9f257b54efe32eda6f99.1464079538.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:24 +00:00
page = alloc_pages(flags, order);
ret = page ? page_address(page) : NULL;
kmemleak_alloc(ret, size, 1, flags);
kasan_kmalloc_large(ret, size, flags);
return ret;
}
EXPORT_SYMBOL(kmalloc_order);
#ifdef CONFIG_TRACING
void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
{
void *ret = kmalloc_order(size, flags, order);
trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
return ret;
}
EXPORT_SYMBOL(kmalloc_order_trace);
#endif
mm: reorganize SLAB freelist randomization The kernel heap allocators are using a sequential freelist making their allocation predictable. This predictability makes kernel heap overflow easier to exploit. An attacker can careful prepare the kernel heap to control the following chunk overflowed. For example these attacks exploit the predictability of the heap: - Linux Kernel CAN SLUB overflow (https://goo.gl/oMNWkU) - Exploiting Linux Kernel Heap corruptions (http://goo.gl/EXLn95) ***Problems that needed solving: - Randomize the Freelist (singled linked) used in the SLUB allocator. - Ensure good performance to encourage usage. - Get best entropy in early boot stage. ***Parts: - 01/02 Reorganize the SLAB Freelist randomization to share elements with the SLUB implementation. - 02/02 The SLUB Freelist randomization implementation. Similar approach than the SLAB but tailored to the singled freelist used in SLUB. ***Performance data: slab_test impact is between 3% to 4% on average for 100000 attempts without smp. It is a very focused testing, kernbench show the overall impact on the system is way lower. Before: Single thread testing ===================== 1. Kmalloc: Repeatedly allocate then free test 100000 times kmalloc(8) -> 49 cycles kfree -> 77 cycles 100000 times kmalloc(16) -> 51 cycles kfree -> 79 cycles 100000 times kmalloc(32) -> 53 cycles kfree -> 83 cycles 100000 times kmalloc(64) -> 62 cycles kfree -> 90 cycles 100000 times kmalloc(128) -> 81 cycles kfree -> 97 cycles 100000 times kmalloc(256) -> 98 cycles kfree -> 121 cycles 100000 times kmalloc(512) -> 95 cycles kfree -> 122 cycles 100000 times kmalloc(1024) -> 96 cycles kfree -> 126 cycles 100000 times kmalloc(2048) -> 115 cycles kfree -> 140 cycles 100000 times kmalloc(4096) -> 149 cycles kfree -> 171 cycles 2. Kmalloc: alloc/free test 100000 times kmalloc(8)/kfree -> 70 cycles 100000 times kmalloc(16)/kfree -> 70 cycles 100000 times kmalloc(32)/kfree -> 70 cycles 100000 times kmalloc(64)/kfree -> 70 cycles 100000 times kmalloc(128)/kfree -> 70 cycles 100000 times kmalloc(256)/kfree -> 69 cycles 100000 times kmalloc(512)/kfree -> 70 cycles 100000 times kmalloc(1024)/kfree -> 73 cycles 100000 times kmalloc(2048)/kfree -> 72 cycles 100000 times kmalloc(4096)/kfree -> 71 cycles After: Single thread testing ===================== 1. Kmalloc: Repeatedly allocate then free test 100000 times kmalloc(8) -> 57 cycles kfree -> 78 cycles 100000 times kmalloc(16) -> 61 cycles kfree -> 81 cycles 100000 times kmalloc(32) -> 76 cycles kfree -> 93 cycles 100000 times kmalloc(64) -> 83 cycles kfree -> 94 cycles 100000 times kmalloc(128) -> 106 cycles kfree -> 107 cycles 100000 times kmalloc(256) -> 118 cycles kfree -> 117 cycles 100000 times kmalloc(512) -> 114 cycles kfree -> 116 cycles 100000 times kmalloc(1024) -> 115 cycles kfree -> 118 cycles 100000 times kmalloc(2048) -> 147 cycles kfree -> 131 cycles 100000 times kmalloc(4096) -> 214 cycles kfree -> 161 cycles 2. Kmalloc: alloc/free test 100000 times kmalloc(8)/kfree -> 66 cycles 100000 times kmalloc(16)/kfree -> 66 cycles 100000 times kmalloc(32)/kfree -> 66 cycles 100000 times kmalloc(64)/kfree -> 66 cycles 100000 times kmalloc(128)/kfree -> 65 cycles 100000 times kmalloc(256)/kfree -> 67 cycles 100000 times kmalloc(512)/kfree -> 67 cycles 100000 times kmalloc(1024)/kfree -> 64 cycles 100000 times kmalloc(2048)/kfree -> 67 cycles 100000 times kmalloc(4096)/kfree -> 67 cycles Kernbench, before: Average Optimal load -j 12 Run (std deviation): Elapsed Time 101.873 (1.16069) User Time 1045.22 (1.60447) System Time 88.969 (0.559195) Percent CPU 1112.9 (13.8279) Context Switches 189140 (2282.15) Sleeps 99008.6 (768.091) After: Average Optimal load -j 12 Run (std deviation): Elapsed Time 102.47 (0.562732) User Time 1045.3 (1.34263) System Time 88.311 (0.342554) Percent CPU 1105.8 (6.49444) Context Switches 189081 (2355.78) Sleeps 99231.5 (800.358) This patch (of 2): This commit reorganizes the previous SLAB freelist randomization to prepare for the SLUB implementation. It moves functions that will be shared to slab_common. The entropy functions are changed to align with the SLUB implementation, now using get_random_(int|long) functions. These functions were chosen because they provide a bit more entropy early on boot and better performance when specific arch instructions are not available. [akpm@linux-foundation.org: fix build] Link: http://lkml.kernel.org/r/1464295031-26375-2-git-send-email-thgarnie@google.com Signed-off-by: Thomas Garnier <thgarnie@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:21:56 +00:00
#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Randomize a generic freelist */
static void freelist_randomize(struct rnd_state *state, unsigned int *list,
size_t count)
{
size_t i;
unsigned int rand;
for (i = 0; i < count; i++)
list[i] = i;
/* Fisher-Yates shuffle */
for (i = count - 1; i > 0; i--) {
rand = prandom_u32_state(state);
rand %= (i + 1);
swap(list[i], list[rand]);
}
}
/* Create a random sequence per cache */
int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
gfp_t gfp)
{
struct rnd_state state;
if (count < 2 || cachep->random_seq)
return 0;
cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
if (!cachep->random_seq)
return -ENOMEM;
/* Get best entropy at this stage of boot */
prandom_seed_state(&state, get_random_long());
freelist_randomize(&state, cachep->random_seq, count);
return 0;
}
/* Destroy the per-cache random freelist sequence */
void cache_random_seq_destroy(struct kmem_cache *cachep)
{
kfree(cachep->random_seq);
cachep->random_seq = NULL;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */
#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
#ifdef CONFIG_SLAB
#define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
#else
#define SLABINFO_RIGHTS S_IRUSR
#endif
static void print_slabinfo_header(struct seq_file *m)
{
/*
* Output format version, so at least we can change it
* without _too_ many complaints.
*/
#ifdef CONFIG_DEBUG_SLAB
seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
#else
seq_puts(m, "slabinfo - version: 2.1\n");
#endif
seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
#ifdef CONFIG_DEBUG_SLAB
seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
#endif
seq_putc(m, '\n');
}
void *slab_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&slab_mutex);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
return seq_list_start(&slab_root_caches, *pos);
}
void *slab_next(struct seq_file *m, void *p, loff_t *pos)
{
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
return seq_list_next(p, &slab_root_caches, pos);
}
void slab_stop(struct seq_file *m, void *p)
{
mutex_unlock(&slab_mutex);
}
static void
memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
{
struct kmem_cache *c;
struct slabinfo sinfo;
if (!is_root_cache(s))
return;
for_each_memcg_cache(c, s) {
memset(&sinfo, 0, sizeof(sinfo));
get_slabinfo(c, &sinfo);
info->active_slabs += sinfo.active_slabs;
info->num_slabs += sinfo.num_slabs;
info->shared_avail += sinfo.shared_avail;
info->active_objs += sinfo.active_objs;
info->num_objs += sinfo.num_objs;
}
}
static void cache_show(struct kmem_cache *s, struct seq_file *m)
{
struct slabinfo sinfo;
memset(&sinfo, 0, sizeof(sinfo));
get_slabinfo(s, &sinfo);
memcg_accumulate_slabinfo(s, &sinfo);
seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
sinfo.objects_per_slab, (1 << sinfo.cache_order));
seq_printf(m, " : tunables %4u %4u %4u",
sinfo.limit, sinfo.batchcount, sinfo.shared);
seq_printf(m, " : slabdata %6lu %6lu %6lu",
sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
slabinfo_show_stats(m, s);
seq_putc(m, '\n');
}
static int slab_show(struct seq_file *m, void *p)
{
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
struct kmem_cache *s = list_entry(p, struct kmem_cache, root_caches_node);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
if (p == slab_root_caches.next)
print_slabinfo_header(m);
slab: implement slab_root_caches list With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. slab_caches currently lists all caches including root and memcg ones. This is the only data structure which lists the root caches and iterating root caches can only be done by walking the list while skipping over memcg caches. As there can be a huge number of memcg caches, this can become very expensive. This also can make /proc/slabinfo behave very badly. seq_file processes reads in 4k chunks and seeks to the previous Nth position on slab_caches list to resume after each chunk. With a lot of memcg cache churns on the list, reading /proc/slabinfo can become very slow and its content often ends up with duplicate and/or missing entries. This patch adds a new list slab_root_caches which lists only the root caches. When memcg is not enabled, it becomes just an alias of slab_caches. memcg specific list operations are collected into memcg_[un]link_cache(). Link: http://lkml.kernel.org/r/20170117235411.9408-7-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov@tarantool.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:24 +00:00
cache_show(s, m);
return 0;
}
mm: oom: show unreclaimable slab info when unreclaimable slabs > user memory The kernel may panic when an oom happens without killable process sometimes it is caused by huge unreclaimable slabs used by kernel. Although kdump could help debug such problem, however, kdump is not available on all architectures and it might be malfunction sometime. And, since kernel already panic it is worthy capturing such information in dmesg to aid touble shooting. Print out unreclaimable slab info (used size and total size) which actual memory usage is not zero (num_objs * size != 0) when unreclaimable slabs amount is greater than total user memory (LRU pages). The output looks like: Unreclaimable slab info: Name Used Total rpc_buffers 31KB 31KB rpc_tasks 7KB 7KB ebitmap_node 1964KB 1964KB avtab_node 5024KB 5024KB xfs_buf 1402KB 1402KB xfs_ili 134KB 134KB xfs_efi_item 115KB 115KB xfs_efd_item 115KB 115KB xfs_buf_item 134KB 134KB xfs_log_item_desc 342KB 342KB xfs_trans 1412KB 1412KB xfs_ifork 212KB 212KB [yang.s@alibaba-inc.com: v11] Link: http://lkml.kernel.org/r/1507656303-103845-4-git-send-email-yang.s@alibaba-inc.com Link: http://lkml.kernel.org/r/1507152550-46205-4-git-send-email-yang.s@alibaba-inc.com Signed-off-by: Yang Shi <yang.s@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-16 01:32:07 +00:00
void dump_unreclaimable_slab(void)
{
struct kmem_cache *s, *s2;
struct slabinfo sinfo;
/*
* Here acquiring slab_mutex is risky since we don't prefer to get
* sleep in oom path. But, without mutex hold, it may introduce a
* risk of crash.
* Use mutex_trylock to protect the list traverse, dump nothing
* without acquiring the mutex.
*/
if (!mutex_trylock(&slab_mutex)) {
pr_warn("excessive unreclaimable slab but cannot dump stats\n");
return;
}
pr_info("Unreclaimable slab info:\n");
pr_info("Name Used Total\n");
list_for_each_entry_safe(s, s2, &slab_caches, list) {
if (!is_root_cache(s) || (s->flags & SLAB_RECLAIM_ACCOUNT))
continue;
get_slabinfo(s, &sinfo);
if (sinfo.num_objs > 0)
pr_info("%-17s %10luKB %10luKB\n", cache_name(s),
(sinfo.active_objs * s->size) / 1024,
(sinfo.num_objs * s->size) / 1024);
}
mutex_unlock(&slab_mutex);
}
#if defined(CONFIG_MEMCG)
slab: link memcg kmem_caches on their associated memory cgroup With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. While a memcg kmem_cache is listed on its root cache's ->children list, there is no direct way to iterate all kmem_caches which are assocaited with a memory cgroup. The only way to iterate them is walking all caches while filtering out caches which don't match, which would be most of them. This makes memcg destruction operations O(N^2) where N is the total number of slab caches which can be huge. This combined with the synchronous RCU operations can tie up a CPU and affect the whole machine for many hours when memory reclaim triggers offlining and destruction of the stale memcgs. This patch adds mem_cgroup->kmem_caches list which goes through memcg_cache_params->kmem_caches_node of all kmem_caches which are associated with the memcg. All memcg specific iterations, including stat file access, are updated to use the new list instead. Link: http://lkml.kernel.org/r/20170117235411.9408-6-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:21 +00:00
void *memcg_slab_start(struct seq_file *m, loff_t *pos)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
mutex_lock(&slab_mutex);
return seq_list_start(&memcg->kmem_caches, *pos);
}
void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
return seq_list_next(p, &memcg->kmem_caches, pos);
}
void memcg_slab_stop(struct seq_file *m, void *p)
{
mutex_unlock(&slab_mutex);
}
int memcg_slab_show(struct seq_file *m, void *p)
{
slab: link memcg kmem_caches on their associated memory cgroup With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. While a memcg kmem_cache is listed on its root cache's ->children list, there is no direct way to iterate all kmem_caches which are assocaited with a memory cgroup. The only way to iterate them is walking all caches while filtering out caches which don't match, which would be most of them. This makes memcg destruction operations O(N^2) where N is the total number of slab caches which can be huge. This combined with the synchronous RCU operations can tie up a CPU and affect the whole machine for many hours when memory reclaim triggers offlining and destruction of the stale memcgs. This patch adds mem_cgroup->kmem_caches list which goes through memcg_cache_params->kmem_caches_node of all kmem_caches which are associated with the memcg. All memcg specific iterations, including stat file access, are updated to use the new list instead. Link: http://lkml.kernel.org/r/20170117235411.9408-6-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:21 +00:00
struct kmem_cache *s = list_entry(p, struct kmem_cache,
memcg_params.kmem_caches_node);
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
slab: link memcg kmem_caches on their associated memory cgroup With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. While a memcg kmem_cache is listed on its root cache's ->children list, there is no direct way to iterate all kmem_caches which are assocaited with a memory cgroup. The only way to iterate them is walking all caches while filtering out caches which don't match, which would be most of them. This makes memcg destruction operations O(N^2) where N is the total number of slab caches which can be huge. This combined with the synchronous RCU operations can tie up a CPU and affect the whole machine for many hours when memory reclaim triggers offlining and destruction of the stale memcgs. This patch adds mem_cgroup->kmem_caches list which goes through memcg_cache_params->kmem_caches_node of all kmem_caches which are associated with the memcg. All memcg specific iterations, including stat file access, are updated to use the new list instead. Link: http://lkml.kernel.org/r/20170117235411.9408-6-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:21 +00:00
if (p == memcg->kmem_caches.next)
print_slabinfo_header(m);
slab: link memcg kmem_caches on their associated memory cgroup With kmem cgroup support enabled, kmem_caches can be created and destroyed frequently and a great number of near empty kmem_caches can accumulate if there are a lot of transient cgroups and the system is not under memory pressure. When memory reclaim starts under such conditions, it can lead to consecutive deactivation and destruction of many kmem_caches, easily hundreds of thousands on moderately large systems, exposing scalability issues in the current slab management code. This is one of the patches to address the issue. While a memcg kmem_cache is listed on its root cache's ->children list, there is no direct way to iterate all kmem_caches which are assocaited with a memory cgroup. The only way to iterate them is walking all caches while filtering out caches which don't match, which would be most of them. This makes memcg destruction operations O(N^2) where N is the total number of slab caches which can be huge. This combined with the synchronous RCU operations can tie up a CPU and affect the whole machine for many hours when memory reclaim triggers offlining and destruction of the stale memcgs. This patch adds mem_cgroup->kmem_caches list which goes through memcg_cache_params->kmem_caches_node of all kmem_caches which are associated with the memcg. All memcg specific iterations, including stat file access, are updated to use the new list instead. Link: http://lkml.kernel.org/r/20170117235411.9408-6-tj@kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jay Vana <jsvana@fb.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 23:41:21 +00:00
cache_show(s, m);
return 0;
}
#endif
/*
* slabinfo_op - iterator that generates /proc/slabinfo
*
* Output layout:
* cache-name
* num-active-objs
* total-objs
* object size
* num-active-slabs
* total-slabs
* num-pages-per-slab
* + further values on SMP and with statistics enabled
*/
static const struct seq_operations slabinfo_op = {
.start = slab_start,
.next = slab_next,
.stop = slab_stop,
.show = slab_show,
};
static int slabinfo_open(struct inode *inode, struct file *file)
{
return seq_open(file, &slabinfo_op);
}
static const struct file_operations proc_slabinfo_operations = {
.open = slabinfo_open,
.read = seq_read,
.write = slabinfo_write,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init slab_proc_init(void)
{
proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
&proc_slabinfo_operations);
return 0;
}
module_init(slab_proc_init);
#endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
static __always_inline void *__do_krealloc(const void *p, size_t new_size,
gfp_t flags)
{
void *ret;
size_t ks = 0;
if (p)
ks = ksize(p);
mm: slub: add kernel address sanitizer support for slub allocator With this patch kasan will be able to catch bugs in memory allocated by slub. Initially all objects in newly allocated slab page, marked as redzone. Later, when allocation of slub object happens, requested by caller number of bytes marked as accessible, and the rest of the object (including slub's metadata) marked as redzone (inaccessible). We also mark object as accessible if ksize was called for this object. There is some places in kernel where ksize function is called to inquire size of really allocated area. Such callers could validly access whole allocated memory, so it should be marked as accessible. Code in slub.c and slab_common.c files could validly access to object's metadata, so instrumentation for this files are disabled. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Signed-off-by: Dmitry Chernenkov <dmitryc@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 22:39:42 +00:00
if (ks >= new_size) {
kasan_krealloc((void *)p, new_size, flags);
return (void *)p;
mm: slub: add kernel address sanitizer support for slub allocator With this patch kasan will be able to catch bugs in memory allocated by slub. Initially all objects in newly allocated slab page, marked as redzone. Later, when allocation of slub object happens, requested by caller number of bytes marked as accessible, and the rest of the object (including slub's metadata) marked as redzone (inaccessible). We also mark object as accessible if ksize was called for this object. There is some places in kernel where ksize function is called to inquire size of really allocated area. Such callers could validly access whole allocated memory, so it should be marked as accessible. Code in slub.c and slab_common.c files could validly access to object's metadata, so instrumentation for this files are disabled. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Signed-off-by: Dmitry Chernenkov <dmitryc@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 22:39:42 +00:00
}
ret = kmalloc_track_caller(new_size, flags);
if (ret && p)
memcpy(ret, p, ks);
return ret;
}
/**
* __krealloc - like krealloc() but don't free @p.
* @p: object to reallocate memory for.
* @new_size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*
* This function is like krealloc() except it never frees the originally
* allocated buffer. Use this if you don't want to free the buffer immediately
* like, for example, with RCU.
*/
void *__krealloc(const void *p, size_t new_size, gfp_t flags)
{
if (unlikely(!new_size))
return ZERO_SIZE_PTR;
return __do_krealloc(p, new_size, flags);
}
EXPORT_SYMBOL(__krealloc);
/**
* krealloc - reallocate memory. The contents will remain unchanged.
* @p: object to reallocate memory for.
* @new_size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*
* The contents of the object pointed to are preserved up to the
* lesser of the new and old sizes. If @p is %NULL, krealloc()
* behaves exactly like kmalloc(). If @new_size is 0 and @p is not a
* %NULL pointer, the object pointed to is freed.
*/
void *krealloc(const void *p, size_t new_size, gfp_t flags)
{
void *ret;
if (unlikely(!new_size)) {
kfree(p);
return ZERO_SIZE_PTR;
}
ret = __do_krealloc(p, new_size, flags);
if (ret && p != ret)
kfree(p);
return ret;
}
EXPORT_SYMBOL(krealloc);
/**
* kzfree - like kfree but zero memory
* @p: object to free memory of
*
* The memory of the object @p points to is zeroed before freed.
* If @p is %NULL, kzfree() does nothing.
*
* Note: this function zeroes the whole allocated buffer which can be a good
* deal bigger than the requested buffer size passed to kmalloc(). So be
* careful when using this function in performance sensitive code.
*/
void kzfree(const void *p)
{
size_t ks;
void *mem = (void *)p;
if (unlikely(ZERO_OR_NULL_PTR(mem)))
return;
ks = ksize(mem);
memset(mem, 0, ks);
kfree(mem);
}
EXPORT_SYMBOL(kzfree);
/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);