commit 6bec6ad77f upstream.
When setting page_owner = on, the following warning can be seen in the
boot log:
WARNING: CPU: 0 PID: 0 at mm/page_alloc.c:2537 drain_all_pages+0x171/0x1a0
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc7-next-20180109-1-default+ #7
Hardware name: Dell Inc. Latitude E7470/0T6HHJ, BIOS 1.11.3 11/09/2016
RIP: 0010:drain_all_pages+0x171/0x1a0
Call Trace:
init_page_owner+0x4e/0x260
start_kernel+0x3e6/0x4a6
? set_init_arg+0x55/0x55
secondary_startup_64+0xa5/0xb0
Code: c5 ed ff 89 df 48 c7 c6 20 3b 71 82 e8 f9 4b 52 00 3b 05 d7 0b f8 00 89 c3 72 d5 5b 5d 41 5
This warning is shown because we are calling drain_all_pages() in
init_early_allocated_pages(), but mm_percpu_wq is not up yet, it is being
set up later on in kernel_init_freeable() -> init_mm_internals().
Link: http://lkml.kernel.org/r/20180109153921.GA13070@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@techadventures.net>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Ayush Mittal <ayush.m@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8d22a93510 upstream.
It was hard to keep a test running, moving tasks between memcgs with
move_charge_at_immigrate, while swapping: mem_cgroup_id_get_many()'s
refcount is discovered to be 0 (supposedly impossible), so it is then
forced to REFCOUNT_SATURATED, and after thousands of warnings in quick
succession, the test is at last put out of misery by being OOM killed.
This is because of the way moved_swap accounting was saved up until the
task move gets completed in __mem_cgroup_clear_mc(), deferred from when
mem_cgroup_move_swap_account() actually exchanged old and new ids.
Concurrent activity can free up swap quicker than the task is scanned,
bringing id refcount down 0 (which should only be possible when
offlining).
Just skip that optimization: do that part of the accounting immediately.
Fixes: 615d66c37c ("mm: memcontrol: fix memcg id ref counter on swap charge move")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2007071431050.4726@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit a68ee05739 ]
There is no need to copy SLUB_STATS items from root memcg cache to new
memcg cache copies. Doing so could result in stack overruns because the
store function only accepts 0 to clear the stat and returns an error for
everything else while the show method would print out the whole stat.
Then, the mismatch of the lengths returns from show and store methods
happens in memcg_propagate_slab_attrs():
else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf))
buf = mbuf;
max_attr_size is only 2 from slab_attr_store(), then, it uses mbuf[64]
in show_stat() later where a bounch of sprintf() would overrun the stack
variable. Fix it by always allocating a page of buffer to be used in
show_stat() if SLUB_STATS=y which should only be used for debug purpose.
# echo 1 > /sys/kernel/slab/fs_cache/shrink
BUG: KASAN: stack-out-of-bounds in number+0x421/0x6e0
Write of size 1 at addr ffffc900256cfde0 by task kworker/76:0/53251
Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
Workqueue: memcg_kmem_cache memcg_kmem_cache_create_func
Call Trace:
number+0x421/0x6e0
vsnprintf+0x451/0x8e0
sprintf+0x9e/0xd0
show_stat+0x124/0x1d0
alloc_slowpath_show+0x13/0x20
__kmem_cache_create+0x47a/0x6b0
addr ffffc900256cfde0 is located in stack of task kworker/76:0/53251 at offset 0 in frame:
process_one_work+0x0/0xb90
this frame has 1 object:
[32, 72) 'lockdep_map'
Memory state around the buggy address:
ffffc900256cfc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc900256cfd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900256cfd80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
^
ffffc900256cfe00: 00 00 00 00 00 f2 f2 f2 00 00 00 00 00 00 00 00
ffffc900256cfe80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: __kmem_cache_create+0x6ac/0x6b0
Workqueue: memcg_kmem_cache memcg_kmem_cache_create_func
Call Trace:
__kmem_cache_create+0x6ac/0x6b0
Fixes: 107dab5c92 ("slub: slub-specific propagation changes")
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Glauber Costa <glauber@scylladb.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>
Link: http://lkml.kernel.org/r/20200429222356.4322-1-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 52f2347808 ]
The slub_debug is able to fix the corrupted slab freelist/page.
However, alloc_debug_processing() only checks the validity of current
and next freepointer during allocation path. As a result, once some
objects have their freepointers corrupted, deactivate_slab() may lead to
page fault.
Below is from a test kernel module when 'slub_debug=PUF,kmalloc-128
slub_nomerge'. The test kernel corrupts the freepointer of one free
object on purpose. Unfortunately, deactivate_slab() does not detect it
when iterating the freechain.
BUG: unable to handle page fault for address: 00000000123456f8
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
... ...
RIP: 0010:deactivate_slab.isra.92+0xed/0x490
... ...
Call Trace:
___slab_alloc+0x536/0x570
__slab_alloc+0x17/0x30
__kmalloc+0x1d9/0x200
ext4_htree_store_dirent+0x30/0xf0
htree_dirblock_to_tree+0xcb/0x1c0
ext4_htree_fill_tree+0x1bc/0x2d0
ext4_readdir+0x54f/0x920
iterate_dir+0x88/0x190
__x64_sys_getdents+0xa6/0x140
do_syscall_64+0x49/0x170
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Therefore, this patch adds extra consistency check in deactivate_slab().
Once an object's freepointer is corrupted, all following objects
starting at this object are isolated.
[akpm@linux-foundation.org: fix build with CONFIG_SLAB_DEBUG=n]
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Jin <joe.jin@oracle.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>
Link: http://lkml.kernel.org/r/20200331031450.12182-1-dongli.zhang@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 243bce09c9 ]
Chris Murphy reports that a slightly overcommitted load, testing swap
and zram along with i915, splats and keeps on splatting, when it had
better fail less noisily:
gnome-shell: page allocation failure: order:0,
mode:0x400d0(__GFP_IO|__GFP_FS|__GFP_COMP|__GFP_RECLAIMABLE),
nodemask=(null),cpuset=/,mems_allowed=0
CPU: 2 PID: 1155 Comm: gnome-shell Not tainted 5.7.0-1.fc33.x86_64 #1
Call Trace:
dump_stack+0x64/0x88
warn_alloc.cold+0x75/0xd9
__alloc_pages_slowpath.constprop.0+0xcfa/0xd30
__alloc_pages_nodemask+0x2df/0x320
alloc_slab_page+0x195/0x310
allocate_slab+0x3c5/0x440
___slab_alloc+0x40c/0x5f0
__slab_alloc+0x1c/0x30
kmem_cache_alloc+0x20e/0x220
xas_nomem+0x28/0x70
add_to_swap_cache+0x321/0x400
__read_swap_cache_async+0x105/0x240
swap_cluster_readahead+0x22c/0x2e0
shmem_swapin+0x8e/0xc0
shmem_swapin_page+0x196/0x740
shmem_getpage_gfp+0x3a2/0xa60
shmem_read_mapping_page_gfp+0x32/0x60
shmem_get_pages+0x155/0x5e0 [i915]
__i915_gem_object_get_pages+0x68/0xa0 [i915]
i915_vma_pin+0x3fe/0x6c0 [i915]
eb_add_vma+0x10b/0x2c0 [i915]
i915_gem_do_execbuffer+0x704/0x3430 [i915]
i915_gem_execbuffer2_ioctl+0x1ea/0x3e0 [i915]
drm_ioctl_kernel+0x86/0xd0 [drm]
drm_ioctl+0x206/0x390 [drm]
ksys_ioctl+0x82/0xc0
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x5b/0xf0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reported on 5.7, but it goes back really to 3.1: when
shmem_read_mapping_page_gfp() was implemented for use by i915, and
allowed for __GFP_NORETRY and __GFP_NOWARN flags in most places, but
missed swapin's "& GFP_KERNEL" mask for page tree node allocation in
__read_swap_cache_async() - that was to mask off HIGHUSER_MOVABLE bits
from what page cache uses, but GFP_RECLAIM_MASK is now what's needed.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=208085
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2006151330070.11064@eggly.anvils
Fixes: 68da9f0557 ("tmpfs: pass gfp to shmem_getpage_gfp")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Chris Murphy <lists@colorremedies.com>
Analyzed-by: Vlastimil Babka <vbabka@suse.cz>
Analyzed-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Chris Murphy <lists@colorremedies.com>
Cc: <stable@vger.kernel.org> [3.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 8982ae527f upstream.
The kzfree() function is normally used to clear some sensitive
information, like encryption keys, in the buffer before freeing it back to
the pool. Memset() is currently used for buffer clearing. However
unlikely, there is still a non-zero probability that the compiler may
choose to optimize away the memory clearing especially if LTO is being
used in the future.
To make sure that this optimization will never happen,
memzero_explicit(), which is introduced in v3.18, is now used in
kzfree() to future-proof it.
Link: http://lkml.kernel.org/r/20200616154311.12314-2-longman@redhat.com
Fixes: 3ef0e5ba46 ("slab: introduce kzfree()")
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Jason A . Donenfeld" <Jason@zx2c4.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c444eb564f upstream.
Write protect anon page faults require an accurate mapcount to decide
if to break the COW or not. This is implemented in the THP path with
reuse_swap_page() ->
page_trans_huge_map_swapcount()/page_trans_huge_mapcount().
If the COW triggers while the other processes sharing the page are
under a huge pmd split, to do an accurate reading, we must ensure the
mapcount isn't computed while it's being transferred from the head
page to the tail pages.
reuse_swap_cache() already runs serialized by the page lock, so it's
enough to add the page lock around __split_huge_pmd_locked too, in
order to add the missing serialization.
Note: the commit in "Fixes" is just to facilitate the backporting,
because the code before such commit didn't try to do an accurate THP
mapcount calculation and it instead used the page_count() to decide if
to COW or not. Both the page_count and the pin_count are THP-wide
refcounts, so they're inaccurate if used in
reuse_swap_page(). Reverting such commit (besides the unrelated fix to
the local anon_vma assignment) would have also opened the window for
memory corruption side effects to certain workloads as documented in
such commit header.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Suggested-by: Jann Horn <jannh@google.com>
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Fixes: 6d0a07edd1 ("mm: thp: calculate the mapcount correctly for THP pages during WP faults")
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d4eaa28378 ]
For kvmalloc'ed data object that contains sensitive information like
cryptographic keys, we need to make sure that the buffer is always cleared
before freeing it. Using memset() alone for buffer clearing may not
provide certainty as the compiler may compile it away. To be sure, the
special memzero_explicit() has to be used.
This patch introduces a new kvfree_sensitive() for freeing those sensitive
data objects allocated by kvmalloc(). The relevant places where
kvfree_sensitive() can be used are modified to use it.
Fixes: 4f0882491a ("KEYS: Avoid false positive ENOMEM error on key read")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Link: http://lkml.kernel.org/r/20200407200318.11711-1-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 5bfea2d9b1 upstream.
The original code in mm/mremap.c checks huge pmd by:
if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
However, a DAX mapped nvdimm is mapped as huge page (by default) but it
is not transparent huge page (_PAGE_PSE | PAGE_DEVMAP). This commit
changes the condition to include the case.
This addresses CVE-2020-10757.
Fixes: 5c7fb56e5e ("mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd")
Cc: <stable@vger.kernel.org>
Reported-by: Fan Yang <Fan_Yang@sjtu.edu.cn>
Signed-off-by: Fan Yang <Fan_Yang@sjtu.edu.cn>
Tested-by: Fan Yang <Fan_Yang@sjtu.edu.cn>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6ade20327d upstream.
find_vmap_area() can return a NULL pointer and we're going to
dereference it without checking it first. Use the existing
find_vm_area() function which does exactly what we want and checks for
the NULL pointer.
Link: http://lkml.kernel.org/r/20181228171009.22269-1-liviu@dudau.co.uk
Fixes: f3c01d2f3a ("mm: vmalloc: avoid racy handling of debugobjects in vunmap")
Signed-off-by: Liviu Dudau <liviu@dudau.co.uk>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit ea0dfeb420 ]
Recent commit 71725ed10c ("mm: huge tmpfs: try to split_huge_page()
when punching hole") has allowed syzkaller to probe deeper, uncovering a
long-standing lockdep issue between the irq-unsafe shmlock_user_lock,
the irq-safe xa_lock on mapping->i_pages, and shmem inode's info->lock
which nests inside xa_lock (or tree_lock) since 4.8's shmem_uncharge().
user_shm_lock(), servicing SysV shmctl(SHM_LOCK), wants
shmlock_user_lock while its caller shmem_lock() holds info->lock with
interrupts disabled; but hugetlbfs_file_setup() calls user_shm_lock()
with interrupts enabled, and might be interrupted by a writeback endio
wanting xa_lock on i_pages.
This may not risk an actual deadlock, since shmem inodes do not take
part in writeback accounting, but there are several easy ways to avoid
it.
Requiring interrupts disabled for shmlock_user_lock would be easy, but
it's a high-level global lock for which that seems inappropriate.
Instead, recall that the use of info->lock to guard info->flags in
shmem_lock() dates from pre-3.1 days, when races with SHMEM_PAGEIN and
SHMEM_TRUNCATE could occur: nowadays it serves no purpose, the only flag
added or removed is VM_LOCKED itself, and calls to shmem_lock() an inode
are already serialized by the caller.
Take info->lock out of the chain and the possibility of deadlock or
lockdep warning goes away.
Fixes: 4595ef88d1 ("shmem: make shmem_inode_info::lock irq-safe")
Reported-by: syzbot+c8a8197c8852f566b9d9@syzkaller.appspotmail.com
Reported-by: syzbot+40b71e145e73f78f81ad@syzkaller.appspotmail.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2004161707410.16322@eggly.anvils
Link: https://lore.kernel.org/lkml/000000000000e5838c05a3152f53@google.com/
Link: https://lore.kernel.org/lkml/0000000000003712b305a331d3b1@google.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit e84fe99b68 upstream.
Without CONFIG_PREEMPT, it can happen that we get soft lockups detected,
e.g., while booting up.
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.6.0-next-20200331+ #4
Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014
RIP: __pageblock_pfn_to_page+0x134/0x1c0
Call Trace:
set_zone_contiguous+0x56/0x70
page_alloc_init_late+0x166/0x176
kernel_init_freeable+0xfa/0x255
kernel_init+0xa/0x106
ret_from_fork+0x35/0x40
The issue becomes visible when having a lot of memory (e.g., 4TB)
assigned to a single NUMA node - a system that can easily be created
using QEMU. Inside VMs on a hypervisor with quite some memory
overcommit, this is fairly easy to trigger.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200416073417.5003-1-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 94b7cc01da upstream.
Syzbot reported the below lockdep splat:
WARNING: possible irq lock inversion dependency detected
5.6.0-rc7-syzkaller #0 Not tainted
--------------------------------------------------------
syz-executor.0/10317 just changed the state of lock:
ffff888021d16568 (&(&info->lock)->rlock){+.+.}, at: spin_lock include/linux/spinlock.h:338 [inline]
ffff888021d16568 (&(&info->lock)->rlock){+.+.}, at: shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
but this lock was taken by another, SOFTIRQ-safe lock in the past:
(&(&xa->xa_lock)->rlock#5){..-.}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&(&info->lock)->rlock);
local_irq_disable();
lock(&(&xa->xa_lock)->rlock#5);
lock(&(&info->lock)->rlock);
<Interrupt>
lock(&(&xa->xa_lock)->rlock#5);
*** DEADLOCK ***
The full report is quite lengthy, please see:
https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2004152007370.13597@eggly.anvils/T/#m813b412c5f78e25ca8c6c7734886ed4de43f241d
It is because CPU 0 held info->lock with IRQ enabled in userfaultfd_copy
path, then CPU 1 is splitting a THP which held xa_lock and info->lock in
IRQ disabled context at the same time. If softirq comes in to acquire
xa_lock, the deadlock would be triggered.
The fix is to acquire/release info->lock with *_irq version instead of
plain spin_{lock,unlock} to make it softirq safe.
Fixes: 4c27fe4c4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Reported-by: syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/r/1587061357-122619-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3c1d7e6ccb upstream.
Our machine encountered a panic(addressing exception) after run for a
long time and the calltrace is:
RIP: hugetlb_fault+0x307/0xbe0
RSP: 0018:ffff9567fc27f808 EFLAGS: 00010286
RAX: e800c03ff1258d48 RBX: ffffd3bb003b69c0 RCX: e800c03ff1258d48
RDX: 17ff3fc00eda72b7 RSI: 00003ffffffff000 RDI: e800c03ff1258d48
RBP: ffff9567fc27f8c8 R08: e800c03ff1258d48 R09: 0000000000000080
R10: ffffaba0704c22a8 R11: 0000000000000001 R12: ffff95c87b4b60d8
R13: 00005fff00000000 R14: 0000000000000000 R15: ffff9567face8074
FS: 00007fe2d9ffb700(0000) GS:ffff956900e40000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffd3bb003b69c0 CR3: 000000be67374000 CR4: 00000000003627e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
follow_hugetlb_page+0x175/0x540
__get_user_pages+0x2a0/0x7e0
__get_user_pages_unlocked+0x15d/0x210
__gfn_to_pfn_memslot+0x3c5/0x460 [kvm]
try_async_pf+0x6e/0x2a0 [kvm]
tdp_page_fault+0x151/0x2d0 [kvm]
...
kvm_arch_vcpu_ioctl_run+0x330/0x490 [kvm]
kvm_vcpu_ioctl+0x309/0x6d0 [kvm]
do_vfs_ioctl+0x3f0/0x540
SyS_ioctl+0xa1/0xc0
system_call_fastpath+0x22/0x27
For 1G hugepages, huge_pte_offset() wants to return NULL or pudp, but it
may return a wrong 'pmdp' if there is a race. Please look at the
following code snippet:
...
pud = pud_offset(p4d, addr);
if (sz != PUD_SIZE && pud_none(*pud))
return NULL;
/* hugepage or swap? */
if (pud_huge(*pud) || !pud_present(*pud))
return (pte_t *)pud;
pmd = pmd_offset(pud, addr);
if (sz != PMD_SIZE && pmd_none(*pmd))
return NULL;
/* hugepage or swap? */
if (pmd_huge(*pmd) || !pmd_present(*pmd))
return (pte_t *)pmd;
...
The following sequence would trigger this bug:
- CPU0: sz = PUD_SIZE and *pud = 0 , continue
- CPU0: "pud_huge(*pud)" is false
- CPU1: calling hugetlb_no_page and set *pud to xxxx8e7(PRESENT)
- CPU0: "!pud_present(*pud)" is false, continue
- CPU0: pmd = pmd_offset(pud, addr) and maybe return a wrong pmdp
However, we want CPU0 to return NULL or pudp in this case.
We must make sure there is exactly one dereference of pud and pmd.
Signed-off-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200413010342.771-1-longpeng2@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit bdebd6a283 upstream.
remap_vmalloc_range() has had various issues with the bounds checks it
promises to perform ("This function checks that addr is a valid
vmalloc'ed area, and that it is big enough to cover the vma") over time,
e.g.:
- not detecting pgoff<<PAGE_SHIFT overflow
- not detecting (pgoff<<PAGE_SHIFT)+usize overflow
- not checking whether addr and addr+(pgoff<<PAGE_SHIFT) are the same
vmalloc allocation
- comparing a potentially wildly out-of-bounds pointer with the end of
the vmalloc region
In particular, since commit fc9702273e ("bpf: Add mmap() support for
BPF_MAP_TYPE_ARRAY"), unprivileged users can cause kernel null pointer
dereferences by calling mmap() on a BPF map with a size that is bigger
than the distance from the start of the BPF map to the end of the
address space.
This could theoretically be used as a kernel ASLR bypass, by using
whether mmap() with a given offset oopses or returns an error code to
perform a binary search over the possible address range.
To allow remap_vmalloc_range_partial() to verify that addr and
addr+(pgoff<<PAGE_SHIFT) are in the same vmalloc region, pass the offset
to remap_vmalloc_range_partial() instead of adding it to the pointer in
remap_vmalloc_range().
In remap_vmalloc_range_partial(), fix the check against
get_vm_area_size() by using size comparisons instead of pointer
comparisons, and add checks for pgoff.
Fixes: 833423143c ("[PATCH] mm: introduce remap_vmalloc_range()")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Link: http://lkml.kernel.org/r/20200415222312.236431-1-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0882ff9190 upstream.
In SLUB, prefetch_freepointer() is used when allocating an object from
cache's freelist, to make sure the next object in the list is cache-hot,
since it's probable it will be allocated soon.
Commit 2482ddec67 ("mm: add SLUB free list pointer obfuscation") has
unintentionally changed the prefetch in a way where the prefetch is
turned to a real fetch, and only the next->next pointer is prefetched.
In case there is not a stream of allocations that would benefit from
prefetching, the extra real fetch might add a useless cache miss to the
allocation. Restore the previous behavior.
Link: http://lkml.kernel.org/r/20180809085245.22448-1-vbabka@suse.cz
Fixes: 2482ddec67 ("mm: add SLUB free list pointer obfuscation")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Eric Dumazet <edumazet@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: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 7ea362427c upstream.
If !area->pages statement is true where memory allocation fails, area is
freed.
In this case 'area->pages = pages' should not executed. So move
'area->pages = pages' after if statement.
[akpm@linux-foundation.org: give area->pages the same treatment]
Link: http://lkml.kernel.org/r/20190830035716.GA190684@LGEARND20B15
Signed-off-by: Austin Kim <austindh.kim@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Roman Penyaev <rpenyaev@suse.de>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8644772637 upstream.
This patch replaces the size + 1 value introduced with the recent fix for 1
byte allocs with a constant value.
The idea here is to reduce code overhead as the previous logic would have
to read size into a register, then increment it, and write it back to
whatever field was being used. By using a constant we can avoid those
memory reads and arithmetic operations in favor of just encoding the
maximum value into the operation itself.
Fixes: 2c2ade8174 ("mm: page_alloc: fix ref bias in page_frag_alloc() for 1-byte allocs")
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1ad53d9fa3 upstream.
Under CONFIG_SLAB_FREELIST_HARDENED=y, the obfuscation was relatively weak
in that the ptr and ptr address were usually so close that the first XOR
would result in an almost entirely 0-byte value[1], leaving most of the
"secret" number ultimately being stored after the third XOR. A single
blind memory content exposure of the freelist was generally sufficient to
learn the secret.
Add a swab() call to mix bits a little more. This is a cheap way (1
cycle) to make attacks need more than a single exposure to learn the
secret (or to know _where_ the exposure is in memory).
kmalloc-32 freelist walk, before:
ptr ptr_addr stored value secret
ffff90c22e019020@ffff90c22e019000 is 86528eb656b3b5bd (86528eb656b3b59d)
ffff90c22e019040@ffff90c22e019020 is 86528eb656b3b5fd (86528eb656b3b59d)
ffff90c22e019060@ffff90c22e019040 is 86528eb656b3b5bd (86528eb656b3b59d)
ffff90c22e019080@ffff90c22e019060 is 86528eb656b3b57d (86528eb656b3b59d)
ffff90c22e0190a0@ffff90c22e019080 is 86528eb656b3b5bd (86528eb656b3b59d)
...
after:
ptr ptr_addr stored value secret
ffff9eed6e019020@ffff9eed6e019000 is 793d1135d52cda42 (86528eb656b3b59d)
ffff9eed6e019040@ffff9eed6e019020 is 593d1135d52cda22 (86528eb656b3b59d)
ffff9eed6e019060@ffff9eed6e019040 is 393d1135d52cda02 (86528eb656b3b59d)
ffff9eed6e019080@ffff9eed6e019060 is 193d1135d52cdae2 (86528eb656b3b59d)
ffff9eed6e0190a0@ffff9eed6e019080 is f93d1135d52cdac2 (86528eb656b3b59d)
[1] https://blog.infosectcbr.com.au/2020/03/weaknesses-in-linux-kernel-heap.html
Fixes: 2482ddec67 ("mm: add SLUB free list pointer obfuscation")
Reported-by: Silvio Cesare <silvio.cesare@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.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: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/202003051623.AF4F8CB@keescook
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[kees: Backport to v4.19 which doesn't call kasan_reset_untag()]
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit aa9f7d5172 upstream.
Using an empty (malformed) nodelist that is not caught during mount option
parsing leads to a stack-out-of-bounds access.
The option string that was used was: "mpol=prefer:,". However,
MPOL_PREFERRED requires a single node number, which is not being provided
here.
Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's
nodeid.
Fixes: 095f1fc4eb ("mempolicy: rework shmem mpol parsing and display")
Reported-by: Entropy Moe <3ntr0py1337@gmail.com>
Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 763802b53a upstream.
Commit 3f8fd02b1b ("mm/vmalloc: Sync unmappings in
__purge_vmap_area_lazy()") introduced a call to vmalloc_sync_all() in
the vunmap() code-path. While this change was necessary to maintain
correctness on x86-32-pae kernels, it also adds additional cycles for
architectures that don't need it.
Specifically on x86-64 with CONFIG_VMAP_STACK=y some people reported
severe performance regressions in micro-benchmarks because it now also
calls the x86-64 implementation of vmalloc_sync_all() on vunmap(). But
the vmalloc_sync_all() implementation on x86-64 is only needed for newly
created mappings.
To avoid the unnecessary work on x86-64 and to gain the performance
back, split up vmalloc_sync_all() into two functions:
* vmalloc_sync_mappings(), and
* vmalloc_sync_unmappings()
Most call-sites to vmalloc_sync_all() only care about new mappings being
synchronized. The only exception is the new call-site added in the
above mentioned commit.
Shile Zhang directed us to a report of an 80% regression in reaim
throughput.
Fixes: 3f8fd02b1b ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Borislav Petkov <bp@suse.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [GHES]
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20191009124418.8286-1-joro@8bytes.org
Link: https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/
Link: http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0715e6c516 upstream.
Sachin reports [1] a crash in SLUB __slab_alloc():
BUG: Kernel NULL pointer dereference on read at 0x000073b0
Faulting instruction address: 0xc0000000003d55f4
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 19 PID: 1 Comm: systemd Not tainted 5.6.0-rc2-next-20200218-autotest #1
NIP: c0000000003d55f4 LR: c0000000003d5b94 CTR: 0000000000000000
REGS: c0000008b37836d0 TRAP: 0300 Not tainted (5.6.0-rc2-next-20200218-autotest)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 24004844 XER: 00000000
CFAR: c00000000000dec4 DAR: 00000000000073b0 DSISR: 40000000 IRQMASK: 1
GPR00: c0000000003d5b94 c0000008b3783960 c00000000155d400 c0000008b301f500
GPR04: 0000000000000dc0 0000000000000002 c0000000003443d8 c0000008bb398620
GPR08: 00000008ba2f0000 0000000000000001 0000000000000000 0000000000000000
GPR12: 0000000024004844 c00000001ec52a00 0000000000000000 0000000000000000
GPR16: c0000008a1b20048 c000000001595898 c000000001750c18 0000000000000002
GPR20: c000000001750c28 c000000001624470 0000000fffffffe0 5deadbeef0000122
GPR24: 0000000000000001 0000000000000dc0 0000000000000002 c0000000003443d8
GPR28: c0000008b301f500 c0000008bb398620 0000000000000000 c00c000002287180
NIP ___slab_alloc+0x1f4/0x760
LR __slab_alloc+0x34/0x60
Call Trace:
___slab_alloc+0x334/0x760 (unreliable)
__slab_alloc+0x34/0x60
__kmalloc_node+0x110/0x490
kvmalloc_node+0x58/0x110
mem_cgroup_css_online+0x108/0x270
online_css+0x48/0xd0
cgroup_apply_control_enable+0x2ec/0x4d0
cgroup_mkdir+0x228/0x5f0
kernfs_iop_mkdir+0x90/0xf0
vfs_mkdir+0x110/0x230
do_mkdirat+0xb0/0x1a0
system_call+0x5c/0x68
This is a PowerPC platform with following NUMA topology:
available: 2 nodes (0-1)
node 0 cpus:
node 0 size: 0 MB
node 0 free: 0 MB
node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
node 1 size: 35247 MB
node 1 free: 30907 MB
node distances:
node 0 1
0: 10 40
1: 40 10
possible numa nodes: 0-31
This only happens with a mmotm patch "mm/memcontrol.c: allocate
shrinker_map on appropriate NUMA node" [2] which effectively calls
kmalloc_node for each possible node. SLUB however only allocates
kmem_cache_node on online N_NORMAL_MEMORY nodes, and relies on
node_to_mem_node to return such valid node for other nodes since commit
a561ce00b0 ("slub: fall back to node_to_mem_node() node if allocating
on memoryless node"). This is however not true in this configuration
where the _node_numa_mem_ array is not initialized for nodes 0 and 2-31,
thus it contains zeroes and get_partial() ends up accessing
non-allocated kmem_cache_node.
A related issue was reported by Bharata (originally by Ramachandran) [3]
where a similar PowerPC configuration, but with mainline kernel without
patch [2] ends up allocating large amounts of pages by kmalloc-1k
kmalloc-512. This seems to have the same underlying issue with
node_to_mem_node() not behaving as expected, and might probably also
lead to an infinite loop with CONFIG_SLUB_CPU_PARTIAL [4].
This patch should fix both issues by not relying on node_to_mem_node()
anymore and instead simply falling back to NUMA_NO_NODE, when
kmalloc_node(node) is attempted for a node that's not online, or has no
usable memory. The "usable memory" condition is also changed from
node_present_pages() to N_NORMAL_MEMORY node state, as that is exactly
the condition that SLUB uses to allocate kmem_cache_node structures.
The check in get_partial() is removed completely, as the checks in
___slab_alloc() are now sufficient to prevent get_partial() being
reached with an invalid node.
[1] https://lore.kernel.org/linux-next/3381CD91-AB3D-4773-BA04-E7A072A63968@linux.vnet.ibm.com/
[2] https://lore.kernel.org/linux-mm/fff0e636-4c36-ed10-281c-8cdb0687c839@virtuozzo.com/
[3] https://lore.kernel.org/linux-mm/20200317092624.GB22538@in.ibm.com/
[4] https://lore.kernel.org/linux-mm/088b5996-faae-8a56-ef9c-5b567125ae54@suse.cz/
Fixes: a561ce00b0 ("slub: fall back to node_to_mem_node() node if allocating on memoryless node")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reported-by: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@in.ibm.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200320115533.9604-1-vbabka@suse.cz
Debugged-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5076190dad upstream.
This is just a cleanup addition to Jann's fix to properly update the
transaction ID for the slub slowpath in commit fd4d9c7d0c ("mm: slub:
add missing TID bump..").
The transaction ID is what protects us against any concurrent accesses,
but we should really also make sure to make the 'freelist' comparison
itself always use the same freelist value that we then used as the new
next free pointer.
Jann points out that if we do all of this carefully, we could skip the
transaction ID update for all the paths that only remove entries from
the lists, and only update the TID when adding entries (to avoid the ABA
issue with cmpxchg and list handling re-adding a previously seen value).
But this patch just does the "make sure to cmpxchg the same value we
used" rather than then try to be clever.
Acked-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 7d36665a58 upstream.
An eventfd monitors multiple memory thresholds of the cgroup, closes them,
the kernel deletes all events related to this eventfd. Before all events
are deleted, another eventfd monitors the memory threshold of this cgroup,
leading to a crash:
BUG: kernel NULL pointer dereference, address: 0000000000000004
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 800000033058e067 P4D 800000033058e067 PUD 3355ce067 PMD 0
Oops: 0002 [#1] SMP PTI
CPU: 2 PID: 14012 Comm: kworker/2:6 Kdump: loaded Not tainted 5.6.0-rc4 #3
Hardware name: LENOVO 20AWS01K00/20AWS01K00, BIOS GLET70WW (2.24 ) 05/21/2014
Workqueue: events memcg_event_remove
RIP: 0010:__mem_cgroup_usage_unregister_event+0xb3/0x190
RSP: 0018:ffffb47e01c4fe18 EFLAGS: 00010202
RAX: 0000000000000001 RBX: ffff8bb223a8a000 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffff8bb22fb83540 RDI: 0000000000000001
RBP: ffffb47e01c4fe48 R08: 0000000000000000 R09: 0000000000000010
R10: 000000000000000c R11: 071c71c71c71c71c R12: ffff8bb226aba880
R13: ffff8bb223a8a480 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8bb242680000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000004 CR3: 000000032c29c003 CR4: 00000000001606e0
Call Trace:
memcg_event_remove+0x32/0x90
process_one_work+0x172/0x380
worker_thread+0x49/0x3f0
kthread+0xf8/0x130
ret_from_fork+0x35/0x40
CR2: 0000000000000004
We can reproduce this problem in the following ways:
1. We create a new cgroup subdirectory and a new eventfd, and then we
monitor multiple memory thresholds of the cgroup through this eventfd.
2. closing this eventfd, and __mem_cgroup_usage_unregister_event ()
will be called multiple times to delete all events related to this
eventfd.
The first time __mem_cgroup_usage_unregister_event() is called, the
kernel will clear all items related to this eventfd in thresholds->
primary.
Since there is currently only one eventfd, thresholds-> primary becomes
empty, so the kernel will set thresholds-> primary and hresholds-> spare
to NULL. If at this time, the user creates a new eventfd and monitor
the memory threshold of this cgroup, kernel will re-initialize
thresholds-> primary.
Then when __mem_cgroup_usage_unregister_event () is called for the
second time, because thresholds-> primary is not empty, the system will
access thresholds-> spare, but thresholds-> spare is NULL, which will
trigger a crash.
In general, the longer it takes to delete all events related to this
eventfd, the easier it is to trigger this problem.
The solution is to check whether the thresholds associated with the
eventfd has been cleared when deleting the event. If so, we do nothing.
[akpm@linux-foundation.org: fix comment, per Kirill]
Fixes: 907860ed38 ("cgroups: make cftype.unregister_event() void-returning")
Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/077a6f67-aefa-4591-efec-f2f3af2b0b02@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit fd4d9c7d0c upstream.
When kmem_cache_alloc_bulk() attempts to allocate N objects from a percpu
freelist of length M, and N > M > 0, it will first remove the M elements
from the percpu freelist, then call ___slab_alloc() to allocate the next
element and repopulate the percpu freelist. ___slab_alloc() can re-enable
IRQs via allocate_slab(), so the TID must be bumped before ___slab_alloc()
to properly commit the freelist head change.
Fix it by unconditionally bumping c->tid when entering the slowpath.
Cc: stable@vger.kernel.org
Fixes: ebe909e0fd ("slub: improve bulk alloc strategy")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d752a49865 ]
If a TCP socket is allocated in IRQ context or cloned from unassociated
(i.e. not associated to a memcg) in IRQ context then it will remain
unassociated for its whole life. Almost half of the TCPs created on the
system are created in IRQ context, so, memory used by such sockets will
not be accounted by the memcg.
This issue is more widespread in cgroup v1 where network memory
accounting is opt-in but it can happen in cgroup v2 if the source socket
for the cloning was created in root memcg.
To fix the issue, just do the association of the sockets at the accept()
time in the process context and then force charge the memory buffer
already used and reserved by the socket.
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e876ecc67d ]
We are testing network memory accounting in our setup and noticed
inconsistent network memory usage and often unrelated cgroups network
usage correlates with testing workload. On further inspection, it
seems like mem_cgroup_sk_alloc() and cgroup_sk_alloc() are broken in
irq context specially for cgroup v1.
mem_cgroup_sk_alloc() and cgroup_sk_alloc() can be called in irq context
and kind of assumes that this can only happen from sk_clone_lock()
and the source sock object has already associated cgroup. However in
cgroup v1, where network memory accounting is opt-in, the source sock
can be unassociated with any cgroup and the new cloned sock can get
associated with unrelated interrupted cgroup.
Cgroup v2 can also suffer if the source sock object was created by
process in the root cgroup or if sk_alloc() is called in irq context.
The fix is to just do nothing in interrupt.
WARNING: Please note that about half of the TCP sockets are allocated
from the IRQ context, so, memory used by such sockets will not be
accouted by the memcg.
The stack trace of mem_cgroup_sk_alloc() from IRQ-context:
CPU: 70 PID: 12720 Comm: ssh Tainted: 5.6.0-smp-DEV #1
Hardware name: ...
Call Trace:
<IRQ>
dump_stack+0x57/0x75
mem_cgroup_sk_alloc+0xe9/0xf0
sk_clone_lock+0x2a7/0x420
inet_csk_clone_lock+0x1b/0x110
tcp_create_openreq_child+0x23/0x3b0
tcp_v6_syn_recv_sock+0x88/0x730
tcp_check_req+0x429/0x560
tcp_v6_rcv+0x72d/0xa40
ip6_protocol_deliver_rcu+0xc9/0x400
ip6_input+0x44/0xd0
? ip6_protocol_deliver_rcu+0x400/0x400
ip6_rcv_finish+0x71/0x80
ipv6_rcv+0x5b/0xe0
? ip6_sublist_rcv+0x2e0/0x2e0
process_backlog+0x108/0x1e0
net_rx_action+0x26b/0x460
__do_softirq+0x104/0x2a6
do_softirq_own_stack+0x2a/0x40
</IRQ>
do_softirq.part.19+0x40/0x50
__local_bh_enable_ip+0x51/0x60
ip6_finish_output2+0x23d/0x520
? ip6table_mangle_hook+0x55/0x160
__ip6_finish_output+0xa1/0x100
ip6_finish_output+0x30/0xd0
ip6_output+0x73/0x120
? __ip6_finish_output+0x100/0x100
ip6_xmit+0x2e3/0x600
? ipv6_anycast_cleanup+0x50/0x50
? inet6_csk_route_socket+0x136/0x1e0
? skb_free_head+0x1e/0x30
inet6_csk_xmit+0x95/0xf0
__tcp_transmit_skb+0x5b4/0xb20
__tcp_send_ack.part.60+0xa3/0x110
tcp_send_ack+0x1d/0x20
tcp_rcv_state_process+0xe64/0xe80
? tcp_v6_connect+0x5d1/0x5f0
tcp_v6_do_rcv+0x1b1/0x3f0
? tcp_v6_do_rcv+0x1b1/0x3f0
__release_sock+0x7f/0xd0
release_sock+0x30/0xa0
__inet_stream_connect+0x1c3/0x3b0
? prepare_to_wait+0xb0/0xb0
inet_stream_connect+0x3b/0x60
__sys_connect+0x101/0x120
? __sys_getsockopt+0x11b/0x140
__x64_sys_connect+0x1a/0x20
do_syscall_64+0x51/0x200
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The stack trace of mem_cgroup_sk_alloc() from IRQ-context:
Fixes: 2d75807383 ("mm: memcontrol: consolidate cgroup socket tracking")
Fixes: d979a39d72 ("cgroup: duplicate cgroup reference when cloning sockets")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8b272b3cbb upstream.
: A user reported a bug against a distribution kernel while running a
: proprietary workload described as "memory intensive that is not swapping"
: that is expected to apply to mainline kernels. The workload is
: read/write/modifying ranges of memory and checking the contents. They
: reported that within a few hours that a bad PMD would be reported followed
: by a memory corruption where expected data was all zeros. A partial
: report of the bad PMD looked like
:
: [ 5195.338482] ../mm/pgtable-generic.c:33: bad pmd ffff8888157ba008(000002e0396009e2)
: [ 5195.341184] ------------[ cut here ]------------
: [ 5195.356880] kernel BUG at ../mm/pgtable-generic.c:35!
: ....
: [ 5195.410033] Call Trace:
: [ 5195.410471] [<ffffffff811bc75d>] change_protection_range+0x7dd/0x930
: [ 5195.410716] [<ffffffff811d4be8>] change_prot_numa+0x18/0x30
: [ 5195.410918] [<ffffffff810adefe>] task_numa_work+0x1fe/0x310
: [ 5195.411200] [<ffffffff81098322>] task_work_run+0x72/0x90
: [ 5195.411246] [<ffffffff81077139>] exit_to_usermode_loop+0x91/0xc2
: [ 5195.411494] [<ffffffff81003a51>] prepare_exit_to_usermode+0x31/0x40
: [ 5195.411739] [<ffffffff815e56af>] retint_user+0x8/0x10
:
: Decoding revealed that the PMD was a valid prot_numa PMD and the bad PMD
: was a false detection. The bug does not trigger if automatic NUMA
: balancing or transparent huge pages is disabled.
:
: The bug is due a race in change_pmd_range between a pmd_trans_huge and
: pmd_nond_or_clear_bad check without any locks held. During the
: pmd_trans_huge check, a parallel protection update under lock can have
: cleared the PMD and filled it with a prot_numa entry between the transhuge
: check and the pmd_none_or_clear_bad check.
:
: While this could be fixed with heavy locking, it's only necessary to make
: a copy of the PMD on the stack during change_pmd_range and avoid races. A
: new helper is created for this as the check if quite subtle and the
: existing similar helpful is not suitable. This passed 154 hours of
: testing (usually triggers between 20 minutes and 24 hours) without
: detecting bad PMDs or corruption. A basic test of an autonuma-intensive
: workload showed no significant change in behaviour.
Although Mel withdrew the patch on the face of LKML comment
https://lkml.org/lkml/2017/4/10/922 the race window aforementioned is
still open, and we have reports of Linpack test reporting bad residuals
after the bad PMD warning is observed. In addition to that, bad
rss-counter and non-zero pgtables assertions are triggered on mm teardown
for the task hitting the bad PMD.
host kernel: mm/pgtable-generic.c:40: bad pmd 00000000b3152f68(8000000d2d2008e7)
....
host kernel: BUG: Bad rss-counter state mm:00000000b583043d idx:1 val:512
host kernel: BUG: non-zero pgtables_bytes on freeing mm: 4096
The issue is observed on a v4.18-based distribution kernel, but the race
window is expected to be applicable to mainline kernels, as well.
[akpm@linux-foundation.org: fix comment typo, per Rafael]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200216191800.22423-1-aquini@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f42f255265 upstream.
If thp defrag setting "defer" is used and a newline is *not* used when
writing to the sysfs file, this is interpreted as the "defer+madvise"
option.
This is because we do prefix matching and if five characters are written
without a newline, the current code ends up comparing to the first five
bytes of the "defer+madvise" option and using that instead.
Use the more appropriate sysfs_streq() that handles the trailing newline
for us. Since this doubles as a nice cleanup, do it in enabled_store()
as well.
The current implementation relies on prefix matching: the number of
bytes compared is either the number of bytes written or the length of
the option being compared. With a newline, "defer\n" does not match
"defer+"madvise"; without a newline, however, "defer" is considered to
match "defer+madvise" (prefix matching is only comparing the first five
bytes). End result is that writing "defer" is broken unless it has an
additional trailing character.
This means that writing "madv" in the past would match and set
"madvise". With strict checking, that no longer is the case but it is
unlikely anybody is currently doing this.
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2001171411020.56385@chino.kir.corp.google.com
Fixes: 21440d7eb9 ("mm, thp: add new defer+madvise defrag option")
Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit cb82962486 upstream.
The page could be a tail page, if this is the case, this BUG_ON will
never be triggered.
Link: http://lkml.kernel.org/r/20200110032610.26499-1-richardw.yang@linux.intel.com
Fixes: e9b61f1985 ("thp: reintroduce split_huge_page()")
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 76073c646f upstream.
Commit 68600f623d ("mm: don't miss the last page because of round-off
error") makes the scan size round up to @denominator regardless of the
memory cgroup's state, online or offline. This affects the overall
reclaiming behavior: the corresponding LRU list is eligible for
reclaiming only when its size logically right shifted by @sc->priority
is bigger than zero in the former formula.
For example, the inactive anonymous LRU list should have at least 0x4000
pages to be eligible for reclaiming when we have 60/12 for
swappiness/priority and without taking scan/rotation ratio into account.
After the roundup is applied, the inactive anonymous LRU list becomes
eligible for reclaiming when its size is bigger than or equal to 0x1000
in the same condition.
(0x4000 >> 12) * 60 / (60 + 140 + 1) = 1
((0x1000 >> 12) * 60) + 200) / (60 + 140 + 1) = 1
aarch64 has 512MB huge page size when the base page size is 64KB. The
memory cgroup that has a huge page is always eligible for reclaiming in
that case.
The reclaiming is likely to stop after the huge page is reclaimed,
meaing the further iteration on @sc->priority and the silbing and child
memory cgroups will be skipped. The overall behaviour has been changed.
This fixes the issue by applying the roundup to offlined memory cgroups
only, to give more preference to reclaim memory from offlined memory
cgroup. It sounds reasonable as those memory is unlikedly to be used by
anyone.
The issue was found by starting up 8 VMs on a Ampere Mustang machine,
which has 8 CPUs and 16 GB memory. Each VM is given with 2 vCPUs and
2GB memory. It took 264 seconds for all VMs to be completely up and
784MB swap is consumed after that. With this patch applied, it took 236
seconds and 60MB swap to do same thing. So there is 10% performance
improvement for my case. Note that KSM is disable while THP is enabled
in the testing.
total used free shared buff/cache available
Mem: 16196 10065 2049 16 4081 3749
Swap: 8175 784 7391
total used free shared buff/cache available
Mem: 16196 11324 3656 24 1215 2936
Swap: 8175 60 8115
Link: http://lkml.kernel.org/r/20200211024514.8730-1-gshan@redhat.com
Fixes: 68600f623d ("mm: don't miss the last page because of round-off error")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org> [4.20+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c7a91bc7c2 upstream.
What we are trying to do is change the '=' character to a NUL terminator
and then at the end of the function we restore it back to an '='. The
problem is there are two error paths where we jump to the end of the
function before we have replaced the '=' with NUL.
We end up putting the '=' in the wrong place (possibly one element
before the start of the buffer).
Link: http://lkml.kernel.org/r/20200115055426.vdjwvry44nfug7yy@kili.mountain
Reported-by: syzbot+e64a13c5369a194d67df@syzkaller.appspotmail.com
Fixes: 095f1fc4eb ("mempolicy: rework shmem mpol parsing and display")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Dmitry Vyukov <dvyukov@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 97d3d0f9a1 ]
Patch series "Fix two above-47bit hint address vs. THP bugs".
The two get_unmapped_area() implementations have to be fixed to provide
THP-friendly mappings if above-47bit hint address is specified.
This patch (of 2):
Filesystems use thp_get_unmapped_area() to provide THP-friendly
mappings. For DAX in particular.
Normally, the kernel doesn't create userspace mappings above 47-bit,
even if the machine allows this (such as with 5-level paging on x86-64).
Not all user space is ready to handle wide addresses. It's known that
at least some JIT compilers use higher bits in pointers to encode their
information.
Userspace can ask for allocation from full address space by specifying
hint address (with or without MAP_FIXED) above 47-bits. If the
application doesn't need a particular address, but wants to allocate
from whole address space it can specify -1 as a hint address.
Unfortunately, this trick breaks thp_get_unmapped_area(): the function
would not try to allocate PMD-aligned area if *any* hint address
specified.
Modify the routine to handle it correctly:
- Try to allocate the space at the specified hint address with length
padding required for PMD alignment.
- If failed, retry without length padding (but with the same hint
address);
- If the returned address matches the hint address return it.
- Otherwise, align the address as required for THP and return.
The user specified hint address is passed down to get_unmapped_area() so
above-47bit hint address will be taken into account without breaking
alignment requirements.
Link: http://lkml.kernel.org/r/20191220142548.7118-2-kirill.shutemov@linux.intel.com
Fixes: b569bab78d ("x86/mm: Prepare to expose larger address space to userspace")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Thomas Willhalm <thomas.willhalm@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Bruggeman, Otto G" <otto.g.bruggeman@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b3b07077b0 ]
__thp_get_unmapped_area is only used in mm/huge_memory.c. Make it static.
Tested by building and booting the kernel.
Link: http://lkml.kernel.org/r/20190504102353.GA22525@bharath12345-Inspiron-5559
Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 6d9e8c651d upstream.
Patch series "use div64_ul() instead of div_u64() if the divisor is
unsigned long".
We were first inspired by commit b0ab99e773 ("sched: Fix possible divide
by zero in avg_atom () calculation"), then refer to the recently analyzed
mm code, we found this suspicious place.
201 if (min) {
202 min *= this_bw;
203 do_div(min, tot_bw);
204 }
And we also disassembled and confirmed it:
/usr/src/debug/kernel-4.9.168-016.ali3000/linux-4.9.168-016.ali3000.alios7.x86_64/mm/page-writeback.c: 201
0xffffffff811c37da <__wb_calc_thresh+234>: xor %r10d,%r10d
0xffffffff811c37dd <__wb_calc_thresh+237>: test %rax,%rax
0xffffffff811c37e0 <__wb_calc_thresh+240>: je 0xffffffff811c3800 <__wb_calc_thresh+272>
/usr/src/debug/kernel-4.9.168-016.ali3000/linux-4.9.168-016.ali3000.alios7.x86_64/mm/page-writeback.c: 202
0xffffffff811c37e2 <__wb_calc_thresh+242>: imul %r8,%rax
/usr/src/debug/kernel-4.9.168-016.ali3000/linux-4.9.168-016.ali3000.alios7.x86_64/mm/page-writeback.c: 203
0xffffffff811c37e6 <__wb_calc_thresh+246>: mov %r9d,%r10d ---> truncates it to 32 bits here
0xffffffff811c37e9 <__wb_calc_thresh+249>: xor %edx,%edx
0xffffffff811c37eb <__wb_calc_thresh+251>: div %r10
0xffffffff811c37ee <__wb_calc_thresh+254>: imul %rbx,%rax
0xffffffff811c37f2 <__wb_calc_thresh+258>: shr $0x2,%rax
0xffffffff811c37f6 <__wb_calc_thresh+262>: mul %rcx
0xffffffff811c37f9 <__wb_calc_thresh+265>: shr $0x2,%rdx
0xffffffff811c37fd <__wb_calc_thresh+269>: mov %rdx,%r10
This series uses div64_ul() instead of div_u64() if the divisor is
unsigned long, to avoid truncation to 32-bit on 64-bit platforms.
This patch (of 3):
The variables 'min' and 'max' are unsigned long and do_div truncates
them to 32 bits, which means it can test non-zero and be truncated to
zero for division. Fix this issue by using div64_ul() instead.
Link: http://lkml.kernel.org/r/20200102081442.8273-2-wenyang@linux.alibaba.com
Fixes: 693108a8a6 ("writeback: make bdi->min/max_ratio handling cgroup writeback aware")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 991589974d upstream.
Shmem/tmpfs tries to provide THP-friendly mappings if huge pages are
enabled. But it doesn't work well with above-47bit hint address.
Normally, the kernel doesn't create userspace mappings above 47-bit,
even if the machine allows this (such as with 5-level paging on x86-64).
Not all user space is ready to handle wide addresses. It's known that
at least some JIT compilers use higher bits in pointers to encode their
information.
Userspace can ask for allocation from full address space by specifying
hint address (with or without MAP_FIXED) above 47-bits. If the
application doesn't need a particular address, but wants to allocate
from whole address space it can specify -1 as a hint address.
Unfortunately, this trick breaks THP alignment in shmem/tmp:
shmem_get_unmapped_area() would not try to allocate PMD-aligned area if
*any* hint address specified.
This can be fixed by requesting the aligned area if the we failed to
allocated at user-specified hint address. The request with inflated
length will also take the user-specified hint address. This way we will
not lose an allocation request from the full address space.
[kirill@shutemov.name: fold in a fixup]
Link: http://lkml.kernel.org/r/20191223231309.t6bh5hkbmokihpfu@box
Link: http://lkml.kernel.org/r/20191220142548.7118-3-kirill.shutemov@linux.intel.com
Fixes: b569bab78d ("x86/mm: Prepare to expose larger address space to userspace")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Willhalm, Thomas" <thomas.willhalm@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Bruggeman, Otto G" <otto.g.bruggeman@intel.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 24cecc3774 upstream.
The ARMv8 64-bit architecture supports execute-only user permissions by
clearing the PTE_USER and PTE_UXN bits, practically making it a mostly
privileged mapping but from which user running at EL0 can still execute.
The downside, however, is that the kernel at EL1 inadvertently reading
such mapping would not trip over the PAN (privileged access never)
protection.
Revert the relevant bits from commit cab15ce604 ("arm64: Introduce
execute-only page access permissions") so that PROT_EXEC implies
PROT_READ (and therefore PTE_USER) until the architecture gains proper
support for execute-only user mappings.
Fixes: cab15ce604 ("arm64: Introduce execute-only page access permissions")
Cc: <stable@vger.kernel.org> # 4.9.x-
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ac8f05da51 upstream.
When zspage is migrated to the other zone, the zone page state should be
updated as well, otherwise the NR_ZSPAGE for each zone shows wrong
counts including proc/zoneinfo in practice.
Link: http://lkml.kernel.org/r/1575434841-48009-1-git-send-email-chanho.min@lge.com
Fixes: 91537fee00 ("mm: add NR_ZSMALLOC to vmstat")
Signed-off-by: Chanho Min <chanho.min@lge.com>
Signed-off-by: Jinsuk Choi <jjinsuk.choi@lge.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org> [4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit aa71ecd8d8 upstream.
In 64bit system. sb->s_maxbytes of shmem filesystem is MAX_LFS_FILESIZE,
which equal LLONG_MAX.
If offset > LLONG_MAX - PAGE_SIZE, offset + len < LLONG_MAX in
shmem_fallocate, which will pass the checking in vfs_fallocate.
/* Check for wrap through zero too */
if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
return -EFBIG;
loff_t unmap_start = round_up(offset, PAGE_SIZE) in shmem_fallocate
causes a overflow.
Syzkaller reports a overflow problem in mm/shmem:
UBSAN: Undefined behaviour in mm/shmem.c:2014:10
signed integer overflow: '9223372036854775807 + 1' cannot be represented in type 'long long int'
CPU: 0 PID:17076 Comm: syz-executor0 Not tainted 4.1.46+ #1
Hardware name: linux, dummy-virt (DT)
Call trace:
dump_backtrace+0x0/0x2c8 arch/arm64/kernel/traps.c:100
show_stack+0x20/0x30 arch/arm64/kernel/traps.c:238
__dump_stack lib/dump_stack.c:15 [inline]
ubsan_epilogue+0x18/0x70 lib/ubsan.c:164
handle_overflow+0x158/0x1b0 lib/ubsan.c:195
shmem_fallocate+0x6d0/0x820 mm/shmem.c:2104
vfs_fallocate+0x238/0x428 fs/open.c:312
SYSC_fallocate fs/open.c:335 [inline]
SyS_fallocate+0x54/0xc8 fs/open.c:239
The highest bit of unmap_start will be appended with sign bit 1
(overflow) when calculate shmem_falloc.start:
shmem_falloc.start = unmap_start >> PAGE_SHIFT.
Fix it by casting the type of unmap_start to u64, when right shifted.
This bug is found in LTS Linux 4.1. It also seems to exist in mainline.
Link: http://lkml.kernel.org/r/1573867464-5107-1-git-send-email-chenjun102@huawei.com
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 13c9aaf7fa ]
Scan through the whole array to see if an update is needed. While we're
at it, use sizeof() to be safe against any possible type changes in the
future.
The bug here is that we wouldn't sync per-cpu counters into global ones
if there was an update of numa_stats for higher cpus. Highly
theoretical one though because it is much more probable that zone_stats
are updated so we would refresh anyway. So I wouldn't bother to mark
this for stable, yet something nice to fix.
[mhocko@suse.com: changelog enhancement]
Link: http://lkml.kernel.org/r/1541601517-17282-1-git-send-email-janne.huttunen@nokia.com
Fixes: 1d90ca897c ("mm: update NUMA counter threshold size")
Signed-off-by: Janne Huttunen <janne.huttunen@nokia.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 8b09549c2b ]
Commit fa5e084e43 ("vmscan: do not unconditionally treat zones that
fail zone_reclaim() as full") changed the return value of
node_reclaim(). The original return value 0 means NODE_RECLAIM_SOME
after this commit.
While the return value of node_reclaim() when CONFIG_NUMA is n is not
changed. This will leads to call zone_watermark_ok() again.
This patch fixes the return value by adjusting to NODE_RECLAIM_NOSCAN.
Since node_reclaim() is only called in page_alloc.c, move it to
mm/internal.h.
Link: http://lkml.kernel.org/r/20181113080436.22078-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 7ce700bf11 upstream.
Let's limit shrinking to !ZONE_DEVICE so we can fix the current code.
We should never try to touch the memmap of offline sections where we
could have uninitialized memmaps and could trigger BUGs when calling
page_to_nid() on poisoned pages.
There is no reliable way to distinguish an uninitialized memmap from an
initialized memmap that belongs to ZONE_DEVICE, as we don't have
anything like SECTION_IS_ONLINE we can use similar to
pfn_to_online_section() for !ZONE_DEVICE memory.
E.g., set_zone_contiguous() similarly relies on pfn_to_online_section()
and will therefore never set a ZONE_DEVICE zone consecutive. Stopping
to shrink the ZONE_DEVICE therefore results in no observable changes,
besides /proc/zoneinfo indicating different boundaries - something we
can totally live with.
Before commit d0dc12e86b ("mm/memory_hotplug: optimize memory
hotplug"), the memmap was initialized with 0 and the node with the right
value. So the zone might be wrong but not garbage. After that commit,
both the zone and the node will be garbage when touching uninitialized
memmaps.
Toshiki reported a BUG (race between delayed initialization of
ZONE_DEVICE memmaps without holding the memory hotplug lock and
concurrent zone shrinking).
https://lkml.org/lkml/2019/11/14/1040
"Iteration of create and destroy namespace causes the panic as below:
kernel BUG at mm/page_alloc.c:535!
CPU: 7 PID: 2766 Comm: ndctl Not tainted 5.4.0-rc4 #6
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:set_pfnblock_flags_mask+0x95/0xf0
Call Trace:
memmap_init_zone_device+0x165/0x17c
memremap_pages+0x4c1/0x540
devm_memremap_pages+0x1d/0x60
pmem_attach_disk+0x16b/0x600 [nd_pmem]
nvdimm_bus_probe+0x69/0x1c0
really_probe+0x1c2/0x3e0
driver_probe_device+0xb4/0x100
device_driver_attach+0x4f/0x60
bind_store+0xc9/0x110
kernfs_fop_write+0x116/0x190
vfs_write+0xa5/0x1a0
ksys_write+0x59/0xd0
do_syscall_64+0x5b/0x180
entry_SYSCALL_64_after_hwframe+0x44/0xa9
While creating a namespace and initializing memmap, if you destroy the
namespace and shrink the zone, it will initialize the memmap outside
the zone and trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page),
pfn), page) in set_pfnblock_flags_mask()."
This BUG is also mitigated by this commit, where we for now stop to
shrink the ZONE_DEVICE zone until we can do it in a safe and clean way.
Link: http://lkml.kernel.org/r/20191006085646.5768-5-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reported-by: Toshiki Fukasawa <t-fukasawa@vx.jp.nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Damian Tometzki <damian.tometzki@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Rich Felker <dalias@libc.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org> [4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 8df1d0e4a2 ]
add_memory() currently does not take the device_hotplug_lock, however
is aleady called under the lock from
arch/powerpc/platforms/pseries/hotplug-memory.c
drivers/acpi/acpi_memhotplug.c
to synchronize against CPU hot-remove and similar.
In general, we should hold the device_hotplug_lock when adding memory to
synchronize against online/offline request (e.g. from user space) - which
already resulted in lock inversions due to device_lock() and
mem_hotplug_lock - see 30467e0b3b ("mm, hotplug: fix concurrent memory
hot-add deadlock"). add_memory()/add_memory_resource() will create memory
block devices, so this really feels like the right thing to do.
Holding the device_hotplug_lock makes sure that a memory block device
can really only be accessed (e.g. via .online/.state) from user space,
once the memory has been fully added to the system.
The lock is not held yet in
drivers/xen/balloon.c
arch/powerpc/platforms/powernv/memtrace.c
drivers/s390/char/sclp_cmd.c
drivers/hv/hv_balloon.c
So, let's either use the locked variants or take the lock.
Don't export add_memory_resource(), as it once was exported to be used by
XEN, which is never built as a module. If somebody requires it, we also
have to export a locked variant (as device_hotplug_lock is never
exported).
Link: http://lkml.kernel.org/r/20180925091457.28651-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 64081362e8 ]
We've recently seen a workload on XFS filesystems with a repeatable
deadlock between background writeback and a multi-process application
doing concurrent writes and fsyncs to a small range of a file.
range_cyclic
writeback Process 1 Process 2
xfs_vm_writepages
write_cache_pages
writeback_index = 2
cycled = 0
....
find page 2 dirty
lock Page 2
->writepage
page 2 writeback
page 2 clean
page 2 added to bio
no more pages
write()
locks page 1
dirties page 1
locks page 2
dirties page 1
fsync()
....
xfs_vm_writepages
write_cache_pages
start index 0
find page 1 towrite
lock Page 1
->writepage
page 1 writeback
page 1 clean
page 1 added to bio
find page 2 towrite
lock Page 2
page 2 is writeback
<blocks>
write()
locks page 1
dirties page 1
fsync()
....
xfs_vm_writepages
write_cache_pages
start index 0
!done && !cycled
sets index to 0, restarts lookup
find page 1 dirty
find page 1 towrite
lock Page 1
page 1 is writeback
<blocks>
lock Page 1
<blocks>
DEADLOCK because:
- process 1 needs page 2 writeback to complete to make
enough progress to issue IO pending for page 1
- writeback needs page 1 writeback to complete so process 2
can progress and unlock the page it is blocked on, then it
can issue the IO pending for page 2
- process 2 can't make progress until process 1 issues IO
for page 1
The underlying cause of the problem here is that range_cyclic writeback is
processing pages in descending index order as we hold higher index pages
in a structure controlled from above write_cache_pages(). The
write_cache_pages() caller needs to be able to submit these pages for IO
before write_cache_pages restarts writeback at mapping index 0 to avoid
wcp inverting the page lock/writeback wait order.
generic_writepages() is not susceptible to this bug as it has no private
context held across write_cache_pages() - filesystems using this
infrastructure always submit pages in ->writepage immediately and so there
is no problem with range_cyclic going back to mapping index 0.
However:
mpage_writepages() has a private bio context,
exofs_writepages() has page_collect
fuse_writepages() has fuse_fill_wb_data
nfs_writepages() has nfs_pageio_descriptor
xfs_vm_writepages() has xfs_writepage_ctx
All of these ->writepages implementations can hold pages under writeback
in their private structures until write_cache_pages() returns, and hence
they are all susceptible to this deadlock.
Also worth noting is that ext4 has it's own bastardised version of
write_cache_pages() and so it /may/ have an equivalent deadlock. I looked
at the code long enough to understand that it has a similar retry loop for
range_cyclic writeback reaching the end of the file and then promptly ran
away before my eyes bled too much. I'll leave it for the ext4 developers
to determine if their code is actually has this deadlock and how to fix it
if it has.
There's a few ways I can see avoid this deadlock. There's probably more,
but these are the first I've though of:
1. get rid of range_cyclic altogether
2. range_cyclic always stops at EOF, and we start again from
writeback index 0 on the next call into write_cache_pages()
2a. wcp also returns EAGAIN to ->writepages implementations to
indicate range cyclic has hit EOF. writepages implementations can
then flush the current context and call wpc again to continue. i.e.
lift the retry into the ->writepages implementation
3. range_cyclic uses trylock_page() rather than lock_page(), and it
skips pages it can't lock without blocking. It will already do this
for pages under writeback, so this seems like a no-brainer
3a. all non-WB_SYNC_ALL writeback uses trylock_page() to avoid
blocking as per pages under writeback.
I don't think #1 is an option - range_cyclic prevents frequently
dirtied lower file offset from starving background writeback of
rarely touched higher file offsets.
#2 is simple, and I don't think it will have any impact on
performance as going back to the start of the file implies an
immediate seek. We'll have exactly the same number of seeks if we
switch writeback to another inode, and then come back to this one
later and restart from index 0.
#2a is pretty much "status quo without the deadlock". Moving the
retry loop up into the wcp caller means we can issue IO on the
pending pages before calling wcp again, and so avoid locking or
waiting on pages in the wrong order. I'm not convinced we need to do
this given that we get the same thing from #2 on the next writeback
call from the writeback infrastructure.
#3 is really just a band-aid - it doesn't fix the access/wait
inversion problem, just prevents it from becoming a deadlock
situation. I'd prefer we fix the inversion, not sweep it under the
carpet like this.
#3a is really an optimisation that just so happens to include the
band-aid fix of #3.
So it seems that the simplest way to fix this issue is to implement
solution #2
Link: http://lkml.kernel.org/r/20181005054526.21507-1-david@fromorbit.com
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 9a63236f1a upstream.
It's possible to hit the WARN_ON_ONCE(page_mapped(page)) in
remove_stable_node() when it races with __mmput() and squeezes in
between ksm_exit() and exit_mmap().
WARNING: CPU: 0 PID: 3295 at mm/ksm.c:888 remove_stable_node+0x10c/0x150
Call Trace:
remove_all_stable_nodes+0x12b/0x330
run_store+0x4ef/0x7b0
kernfs_fop_write+0x200/0x420
vfs_write+0x154/0x450
ksys_write+0xf9/0x1d0
do_syscall_64+0x99/0x510
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Remove the warning as there is nothing scary going on.
Link: http://lkml.kernel.org/r/20191119131850.5675-1-aryabinin@virtuozzo.com
Fixes: cbf86cfe04 ("ksm: remove old stable nodes more thoroughly")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 656d571193 upstream.
We recently started updating the node span based on the zone span to
avoid touching uninitialized memmaps.
Currently, we will always detect the node span to start at 0, meaning a
node can easily span too many pages. pgdat_is_empty() will still work
correctly if all zones span no pages. We should skip over all zones
without spanned pages and properly handle the first detected zone that
spans pages.
Unfortunately, in contrast to the zone span (/proc/zoneinfo), the node
span cannot easily be inspected and tested. The node span gives no real
guarantees when an architecture supports memory hotplug, meaning it can
easily contain holes or span pages of different nodes.
The node span is not really used after init on architectures that
support memory hotplug.
E.g., we use it in mm/memory_hotplug.c:try_offline_node() and in
mm/kmemleak.c:kmemleak_scan(). These users seem to be fine.
Link: http://lkml.kernel.org/r/20191027222714.5313-1-david@redhat.com
Fixes: 00d6c019b5 ("mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 00d6c019b5 upstream.
We might use the nid of memmaps that were never initialized. For
example, if the memmap was poisoned, we will crash the kernel in
pfn_to_nid() right now. Let's use the calculated boundaries of the
separate zones instead. This now also avoids having to iterate over a
whole bunch of subsections again, after shrinking one zone.
Before commit d0dc12e86b ("mm/memory_hotplug: optimize memory
hotplug"), the memmap was initialized to 0 and the node was set to the
right value. After that commit, the node might be garbage.
We'll have to fix shrink_zone_span() next.
Link: http://lkml.kernel.org/r/20191006085646.5768-4-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Damian Tometzki <damian.tometzki@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Rich Felker <dalias@libc.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org> [4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit 391d4ee568 ("memfd: Fix locking when tagging pins")
introduces the following warning messages.
*WARNING: suspicious RCU usage in memfd_wait_for_pins*
It is because we still use radix_tree_deref_slot without read_rcu_lock.
We should use radix_tree_deref_slot_protected instead in the case.
Cc: stable@vger.kernel.org
Fixes: 391d4ee568 ("memfd: Fix locking when tagging pins")
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Oscar Salvador