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linux-stable/mm/memcontrol.c
Matthew Wilcox (Oracle) be5a9e17a2 memcg: remove mem_cgroup_uncharge_list() 
All users have been converted to mem_cgroup_uncharge_folios() so we can
remove this API.

Link: https://lkml.kernel.org/r/20240227174254.710559-14-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-03-04 17:01:25 -08:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* memcontrol.c - Memory Controller
*
* Copyright IBM Corporation, 2007
* Author Balbir Singh <balbir@linux.vnet.ibm.com>
*
* Copyright 2007 OpenVZ SWsoft Inc
* Author: Pavel Emelianov <xemul@openvz.org>
*
* Memory thresholds
* Copyright (C) 2009 Nokia Corporation
* Author: Kirill A. Shutemov
*
* Kernel Memory Controller
* Copyright (C) 2012 Parallels Inc. and Google Inc.
* Authors: Glauber Costa and Suleiman Souhlal
*
* Native page reclaim
* Charge lifetime sanitation
* Lockless page tracking & accounting
* Unified hierarchy configuration model
* Copyright (C) 2015 Red Hat, Inc., Johannes Weiner
*
* Per memcg lru locking
* Copyright (C) 2020 Alibaba, Inc, Alex Shi
*/
#include <linux/page_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
#include <linux/pagewalk.h>
#include <linux/sched/mm.h>
#include <linux/shmem_fs.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/vm_event_item.h>
#include <linux/smp.h>
#include <linux/page-flags.h>
#include <linux/backing-dev.h>
#include <linux/bit_spinlock.h>
#include <linux/rcupdate.h>
#include <linux/limits.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/spinlock.h>
#include <linux/eventfd.h>
#include <linux/poll.h>
#include <linux/sort.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/vmpressure.h>
#include <linux/memremap.h>
#include <linux/mm_inline.h>
#include <linux/swap_cgroup.h>
#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/lockdep.h>
#include <linux/file.h>
#include <linux/resume_user_mode.h>
#include <linux/psi.h>
#include <linux/seq_buf.h>
#include <linux/sched/isolation.h>
#include <linux/kmemleak.h>
#include "internal.h"
#include <net/sock.h>
#include <net/ip.h>
#include "slab.h"
#include "swap.h"
#include <linux/uaccess.h>
#include <trace/events/vmscan.h>
struct cgroup_subsys memory_cgrp_subsys __read_mostly;
EXPORT_SYMBOL(memory_cgrp_subsys);
struct mem_cgroup *root_mem_cgroup __read_mostly;
/* Active memory cgroup to use from an interrupt context */
DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg);
EXPORT_PER_CPU_SYMBOL_GPL(int_active_memcg);
/* Socket memory accounting disabled? */
static bool cgroup_memory_nosocket __ro_after_init;
/* Kernel memory accounting disabled? */
static bool cgroup_memory_nokmem __ro_after_init;
/* BPF memory accounting disabled? */
static bool cgroup_memory_nobpf __ro_after_init;
#ifdef CONFIG_CGROUP_WRITEBACK
static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
#endif
/* Whether legacy memory+swap accounting is active */
static bool do_memsw_account(void)
{
return !cgroup_subsys_on_dfl(memory_cgrp_subsys);
}
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
/*
* Cgroups above their limits are maintained in a RB-Tree, independent of
* their hierarchy representation
*/
struct mem_cgroup_tree_per_node {
struct rb_root rb_root;
struct rb_node *rb_rightmost;
spinlock_t lock;
};
struct mem_cgroup_tree {
struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
};
static struct mem_cgroup_tree soft_limit_tree __read_mostly;
/* for OOM */
struct mem_cgroup_eventfd_list {
struct list_head list;
struct eventfd_ctx *eventfd;
};
/*
* cgroup_event represents events which userspace want to receive.
*/
struct mem_cgroup_event {
/*
* memcg which the event belongs to.
*/
struct mem_cgroup *memcg;
/*
* eventfd to signal userspace about the event.
*/
struct eventfd_ctx *eventfd;
/*
* Each of these stored in a list by the cgroup.
*/
struct list_head list;
/*
* register_event() callback will be used to add new userspace
* waiter for changes related to this event. Use eventfd_signal()
* on eventfd to send notification to userspace.
*/
int (*register_event)(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args);
/*
* unregister_event() callback will be called when userspace closes
* the eventfd or on cgroup removing. This callback must be set,
* if you want provide notification functionality.
*/
void (*unregister_event)(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd);
/*
* All fields below needed to unregister event when
* userspace closes eventfd.
*/
poll_table pt;
wait_queue_head_t *wqh;
wait_queue_entry_t wait;
struct work_struct remove;
};
static void mem_cgroup_threshold(struct mem_cgroup *memcg);
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
/* Stuffs for move charges at task migration. */
/*
* Types of charges to be moved.
*/
#define MOVE_ANON 0x1U
#define MOVE_FILE 0x2U
#define MOVE_MASK (MOVE_ANON | MOVE_FILE)
/* "mc" and its members are protected by cgroup_mutex */
static struct move_charge_struct {
spinlock_t lock; /* for from, to */
struct mm_struct *mm;
struct mem_cgroup *from;
struct mem_cgroup *to;
unsigned long flags;
unsigned long precharge;
unsigned long moved_charge;
unsigned long moved_swap;
struct task_struct *moving_task; /* a task moving charges */
wait_queue_head_t waitq; /* a waitq for other context */
} mc = {
.lock = __SPIN_LOCK_UNLOCKED(mc.lock),
.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};
/*
* Maximum loops in mem_cgroup_soft_reclaim(), used for soft
* limit reclaim to prevent infinite loops, if they ever occur.
*/
#define MEM_CGROUP_MAX_RECLAIM_LOOPS 100
#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2
/* for encoding cft->private value on file */
enum res_type {
_MEM,
_MEMSWAP,
_KMEM,
_TCP,
};
#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
#define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
/*
* Iteration constructs for visiting all cgroups (under a tree). If
* loops are exited prematurely (break), mem_cgroup_iter_break() must
* be used for reference counting.
*/
#define for_each_mem_cgroup_tree(iter, root) \
for (iter = mem_cgroup_iter(root, NULL, NULL); \
iter != NULL; \
iter = mem_cgroup_iter(root, iter, NULL))
#define for_each_mem_cgroup(iter) \
for (iter = mem_cgroup_iter(NULL, NULL, NULL); \
iter != NULL; \
iter = mem_cgroup_iter(NULL, iter, NULL))
static inline bool task_is_dying(void)
{
return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||
(current->flags & PF_EXITING);
}
/* Some nice accessors for the vmpressure. */
struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
{
if (!memcg)
memcg = root_mem_cgroup;
return &memcg->vmpressure;
}
struct mem_cgroup *vmpressure_to_memcg(struct vmpressure *vmpr)
{
return container_of(vmpr, struct mem_cgroup, vmpressure);
}
#define CURRENT_OBJCG_UPDATE_BIT 0
#define CURRENT_OBJCG_UPDATE_FLAG (1UL << CURRENT_OBJCG_UPDATE_BIT)
#ifdef CONFIG_MEMCG_KMEM
static DEFINE_SPINLOCK(objcg_lock);
bool mem_cgroup_kmem_disabled(void)
{
return cgroup_memory_nokmem;
}
static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
unsigned int nr_pages);
static void obj_cgroup_release(struct percpu_ref *ref)
{
struct obj_cgroup *objcg = container_of(ref, struct obj_cgroup, refcnt);
unsigned int nr_bytes;
unsigned int nr_pages;
unsigned long flags;
/*
* At this point all allocated objects are freed, and
* objcg->nr_charged_bytes can't have an arbitrary byte value.
* However, it can be PAGE_SIZE or (x * PAGE_SIZE).
*
* The following sequence can lead to it:
* 1) CPU0: objcg == stock->cached_objcg
* 2) CPU1: we do a small allocation (e.g. 92 bytes),
* PAGE_SIZE bytes are charged
* 3) CPU1: a process from another memcg is allocating something,
* the stock if flushed,
* objcg->nr_charged_bytes = PAGE_SIZE - 92
* 5) CPU0: we do release this object,
* 92 bytes are added to stock->nr_bytes
* 6) CPU0: stock is flushed,
* 92 bytes are added to objcg->nr_charged_bytes
*
* In the result, nr_charged_bytes == PAGE_SIZE.
* This page will be uncharged in obj_cgroup_release().
*/
nr_bytes = atomic_read(&objcg->nr_charged_bytes);
WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1));
nr_pages = nr_bytes >> PAGE_SHIFT;
if (nr_pages)
obj_cgroup_uncharge_pages(objcg, nr_pages);
spin_lock_irqsave(&objcg_lock, flags);
list_del(&objcg->list);
spin_unlock_irqrestore(&objcg_lock, flags);
percpu_ref_exit(ref);
kfree_rcu(objcg, rcu);
}
static struct obj_cgroup *obj_cgroup_alloc(void)
{
struct obj_cgroup *objcg;
int ret;
objcg = kzalloc(sizeof(struct obj_cgroup), GFP_KERNEL);
if (!objcg)
return NULL;
ret = percpu_ref_init(&objcg->refcnt, obj_cgroup_release, 0,
GFP_KERNEL);
if (ret) {
kfree(objcg);
return NULL;
}
INIT_LIST_HEAD(&objcg->list);
return objcg;
}
static void memcg_reparent_objcgs(struct mem_cgroup *memcg,
struct mem_cgroup *parent)
{
struct obj_cgroup *objcg, *iter;
objcg = rcu_replace_pointer(memcg->objcg, NULL, true);
spin_lock_irq(&objcg_lock);
/* 1) Ready to reparent active objcg. */
list_add(&objcg->list, &memcg->objcg_list);
/* 2) Reparent active objcg and already reparented objcgs to parent. */
list_for_each_entry(iter, &memcg->objcg_list, list)
WRITE_ONCE(iter->memcg, parent);
/* 3) Move already reparented objcgs to the parent's list */
list_splice(&memcg->objcg_list, &parent->objcg_list);
spin_unlock_irq(&objcg_lock);
percpu_ref_kill(&objcg->refcnt);
}
/*
* A lot of the calls to the cache allocation functions are expected to be
* inlined by the compiler. Since the calls to memcg_slab_pre_alloc_hook() are
* conditional to this static branch, we'll have to allow modules that does
* kmem_cache_alloc and the such to see this symbol as well
*/
DEFINE_STATIC_KEY_FALSE(memcg_kmem_online_key);
EXPORT_SYMBOL(memcg_kmem_online_key);
DEFINE_STATIC_KEY_FALSE(memcg_bpf_enabled_key);
EXPORT_SYMBOL(memcg_bpf_enabled_key);
#endif
/**
* mem_cgroup_css_from_folio - css of the memcg associated with a folio
* @folio: folio of interest
*
* If memcg is bound to the default hierarchy, css of the memcg associated
* with @folio is returned. The returned css remains associated with @folio
* until it is released.
*
* If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup
* is returned.
*/
struct cgroup_subsys_state *mem_cgroup_css_from_folio(struct folio *folio)
{
struct mem_cgroup *memcg = folio_memcg(folio);
if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
memcg = root_mem_cgroup;
return &memcg->css;
}
/**
* page_cgroup_ino - return inode number of the memcg a page is charged to
* @page: the page
*
* Look up the closest online ancestor of the memory cgroup @page is charged to
* and return its inode number or 0 if @page is not charged to any cgroup. It
* is safe to call this function without holding a reference to @page.
*
* Note, this function is inherently racy, because there is nothing to prevent
* the cgroup inode from getting torn down and potentially reallocated a moment
* after page_cgroup_ino() returns, so it only should be used by callers that
* do not care (such as procfs interfaces).
*/
ino_t page_cgroup_ino(struct page *page)
{
struct mem_cgroup *memcg;
unsigned long ino = 0;
rcu_read_lock();
/* page_folio() is racy here, but the entire function is racy anyway */
memcg = folio_memcg_check(page_folio(page));
while (memcg && !(memcg->css.flags & CSS_ONLINE))
memcg = parent_mem_cgroup(memcg);
if (memcg)
ino = cgroup_ino(memcg->css.cgroup);
rcu_read_unlock();
return ino;
}
static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz,
unsigned long new_usage_in_excess)
{
struct rb_node **p = &mctz->rb_root.rb_node;
struct rb_node *parent = NULL;
struct mem_cgroup_per_node *mz_node;
bool rightmost = true;
if (mz->on_tree)
return;
mz->usage_in_excess = new_usage_in_excess;
if (!mz->usage_in_excess)
return;
while (*p) {
parent = *p;
mz_node = rb_entry(parent, struct mem_cgroup_per_node,
tree_node);
if (mz->usage_in_excess < mz_node->usage_in_excess) {
p = &(*p)->rb_left;
rightmost = false;
} else {
p = &(*p)->rb_right;
}
}
if (rightmost)
mctz->rb_rightmost = &mz->tree_node;
rb_link_node(&mz->tree_node, parent, p);
rb_insert_color(&mz->tree_node, &mctz->rb_root);
mz->on_tree = true;
}
static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz)
{
if (!mz->on_tree)
return;
if (&mz->tree_node == mctz->rb_rightmost)
mctz->rb_rightmost = rb_prev(&mz->tree_node);
rb_erase(&mz->tree_node, &mctz->rb_root);
mz->on_tree = false;
}
static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz)
{
unsigned long flags;
spin_lock_irqsave(&mctz->lock, flags);
__mem_cgroup_remove_exceeded(mz, mctz);
spin_unlock_irqrestore(&mctz->lock, flags);
}
static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
{
unsigned long nr_pages = page_counter_read(&memcg->memory);
unsigned long soft_limit = READ_ONCE(memcg->soft_limit);
unsigned long excess = 0;
if (nr_pages > soft_limit)
excess = nr_pages - soft_limit;
return excess;
}
static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
{
unsigned long excess;
struct mem_cgroup_per_node *mz;
struct mem_cgroup_tree_per_node *mctz;
if (lru_gen_enabled()) {
if (soft_limit_excess(memcg))
lru_gen_soft_reclaim(memcg, nid);
return;
}
mctz = soft_limit_tree.rb_tree_per_node[nid];
if (!mctz)
return;
/*
* Necessary to update all ancestors when hierarchy is used.
* because their event counter is not touched.
*/
for (; memcg; memcg = parent_mem_cgroup(memcg)) {
mz = memcg->nodeinfo[nid];
excess = soft_limit_excess(memcg);
/*
* We have to update the tree if mz is on RB-tree or
* mem is over its softlimit.
*/
if (excess || mz->on_tree) {
unsigned long flags;
spin_lock_irqsave(&mctz->lock, flags);
/* if on-tree, remove it */
if (mz->on_tree)
__mem_cgroup_remove_exceeded(mz, mctz);
/*
* Insert again. mz->usage_in_excess will be updated.
* If excess is 0, no tree ops.
*/
__mem_cgroup_insert_exceeded(mz, mctz, excess);
spin_unlock_irqrestore(&mctz->lock, flags);
}
}
}
static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
{
struct mem_cgroup_tree_per_node *mctz;
struct mem_cgroup_per_node *mz;
int nid;
for_each_node(nid) {
mz = memcg->nodeinfo[nid];
mctz = soft_limit_tree.rb_tree_per_node[nid];
if (mctz)
mem_cgroup_remove_exceeded(mz, mctz);
}
}
static struct mem_cgroup_per_node *
__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
{
struct mem_cgroup_per_node *mz;
retry:
mz = NULL;
if (!mctz->rb_rightmost)
goto done; /* Nothing to reclaim from */
mz = rb_entry(mctz->rb_rightmost,
struct mem_cgroup_per_node, tree_node);
/*
* Remove the node now but someone else can add it back,
* we will to add it back at the end of reclaim to its correct
* position in the tree.
*/
__mem_cgroup_remove_exceeded(mz, mctz);
if (!soft_limit_excess(mz->memcg) ||
!css_tryget(&mz->memcg->css))
goto retry;
done:
return mz;
}
static struct mem_cgroup_per_node *
mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
{
struct mem_cgroup_per_node *mz;
spin_lock_irq(&mctz->lock);
mz = __mem_cgroup_largest_soft_limit_node(mctz);
spin_unlock_irq(&mctz->lock);
return mz;
}
/* Subset of vm_event_item to report for memcg event stats */
static const unsigned int memcg_vm_event_stat[] = {
PGPGIN,
PGPGOUT,
PGSCAN_KSWAPD,
PGSCAN_DIRECT,
PGSCAN_KHUGEPAGED,
PGSTEAL_KSWAPD,
PGSTEAL_DIRECT,
PGSTEAL_KHUGEPAGED,
PGFAULT,
PGMAJFAULT,
PGREFILL,
PGACTIVATE,
PGDEACTIVATE,
PGLAZYFREE,
PGLAZYFREED,
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
ZSWPIN,
ZSWPOUT,
ZSWPWB,
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
THP_FAULT_ALLOC,
THP_COLLAPSE_ALLOC,
THP_SWPOUT,
THP_SWPOUT_FALLBACK,
#endif
};
#define NR_MEMCG_EVENTS ARRAY_SIZE(memcg_vm_event_stat)
static int mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly;
static void init_memcg_events(void)
{
int i;
for (i = 0; i < NR_MEMCG_EVENTS; ++i)
mem_cgroup_events_index[memcg_vm_event_stat[i]] = i + 1;
}
static inline int memcg_events_index(enum vm_event_item idx)
{
return mem_cgroup_events_index[idx] - 1;
}
struct memcg_vmstats_percpu {
/* Stats updates since the last flush */
unsigned int stats_updates;
/* Cached pointers for fast iteration in memcg_rstat_updated() */
struct memcg_vmstats_percpu *parent;
struct memcg_vmstats *vmstats;
/* The above should fit a single cacheline for memcg_rstat_updated() */
/* Local (CPU and cgroup) page state & events */
long state[MEMCG_NR_STAT];
unsigned long events[NR_MEMCG_EVENTS];
/* Delta calculation for lockless upward propagation */
long state_prev[MEMCG_NR_STAT];
unsigned long events_prev[NR_MEMCG_EVENTS];
/* Cgroup1: threshold notifications & softlimit tree updates */
unsigned long nr_page_events;
unsigned long targets[MEM_CGROUP_NTARGETS];
} ____cacheline_aligned;
struct memcg_vmstats {
/* Aggregated (CPU and subtree) page state & events */
long state[MEMCG_NR_STAT];
unsigned long events[NR_MEMCG_EVENTS];
/* Non-hierarchical (CPU aggregated) page state & events */
long state_local[MEMCG_NR_STAT];
unsigned long events_local[NR_MEMCG_EVENTS];
/* Pending child counts during tree propagation */
long state_pending[MEMCG_NR_STAT];
unsigned long events_pending[NR_MEMCG_EVENTS];
/* Stats updates since the last flush */
atomic64_t stats_updates;
};
/*
* memcg and lruvec stats flushing
*
* Many codepaths leading to stats update or read are performance sensitive and
* adding stats flushing in such codepaths is not desirable. So, to optimize the
* flushing the kernel does:
*
* 1) Periodically and asynchronously flush the stats every 2 seconds to not let
* rstat update tree grow unbounded.
*
* 2) Flush the stats synchronously on reader side only when there are more than
* (MEMCG_CHARGE_BATCH * nr_cpus) update events. Though this optimization
* will let stats be out of sync by atmost (MEMCG_CHARGE_BATCH * nr_cpus) but
* only for 2 seconds due to (1).
*/
static void flush_memcg_stats_dwork(struct work_struct *w);
static DECLARE_DEFERRABLE_WORK(stats_flush_dwork, flush_memcg_stats_dwork);
static u64 flush_last_time;
#define FLUSH_TIME (2UL*HZ)
/*
* Accessors to ensure that preemption is disabled on PREEMPT_RT because it can
* not rely on this as part of an acquired spinlock_t lock. These functions are
* never used in hardirq context on PREEMPT_RT and therefore disabling preemtion
* is sufficient.
*/
static void memcg_stats_lock(void)
{
preempt_disable_nested();
VM_WARN_ON_IRQS_ENABLED();
}
static void __memcg_stats_lock(void)
{
preempt_disable_nested();
}
static void memcg_stats_unlock(void)
{
preempt_enable_nested();
}
static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats)
{
return atomic64_read(&vmstats->stats_updates) >
MEMCG_CHARGE_BATCH * num_online_cpus();
}
static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val)
{
struct memcg_vmstats_percpu *statc;
int cpu = smp_processor_id();
if (!val)
return;
cgroup_rstat_updated(memcg->css.cgroup, cpu);
statc = this_cpu_ptr(memcg->vmstats_percpu);
for (; statc; statc = statc->parent) {
statc->stats_updates += abs(val);
if (statc->stats_updates < MEMCG_CHARGE_BATCH)
continue;
/*
* If @memcg is already flush-able, increasing stats_updates is
* redundant. Avoid the overhead of the atomic update.
*/
if (!memcg_vmstats_needs_flush(statc->vmstats))
atomic64_add(statc->stats_updates,
&statc->vmstats->stats_updates);
statc->stats_updates = 0;
}
}
static void do_flush_stats(struct mem_cgroup *memcg)
{
if (mem_cgroup_is_root(memcg))
WRITE_ONCE(flush_last_time, jiffies_64);
cgroup_rstat_flush(memcg->css.cgroup);
}
/*
* mem_cgroup_flush_stats - flush the stats of a memory cgroup subtree
* @memcg: root of the subtree to flush
*
* Flushing is serialized by the underlying global rstat lock. There is also a
* minimum amount of work to be done even if there are no stat updates to flush.
* Hence, we only flush the stats if the updates delta exceeds a threshold. This
* avoids unnecessary work and contention on the underlying lock.
*/
void mem_cgroup_flush_stats(struct mem_cgroup *memcg)
{
if (mem_cgroup_disabled())
return;
if (!memcg)
memcg = root_mem_cgroup;
if (memcg_vmstats_needs_flush(memcg->vmstats))
do_flush_stats(memcg);
}
void mem_cgroup_flush_stats_ratelimited(struct mem_cgroup *memcg)
{
/* Only flush if the periodic flusher is one full cycle late */
if (time_after64(jiffies_64, READ_ONCE(flush_last_time) + 2*FLUSH_TIME))
mem_cgroup_flush_stats(memcg);
}
static void flush_memcg_stats_dwork(struct work_struct *w)
{
/*
* Deliberately ignore memcg_vmstats_needs_flush() here so that flushing
* in latency-sensitive paths is as cheap as possible.
*/
do_flush_stats(root_mem_cgroup);
queue_delayed_work(system_unbound_wq, &stats_flush_dwork, FLUSH_TIME);
}
unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx)
{
long x = READ_ONCE(memcg->vmstats->state[idx]);
#ifdef CONFIG_SMP
if (x < 0)
x = 0;
#endif
return x;
}
static int memcg_page_state_unit(int item);
/*
* Normalize the value passed into memcg_rstat_updated() to be in pages. Round
* up non-zero sub-page updates to 1 page as zero page updates are ignored.
*/
static int memcg_state_val_in_pages(int idx, int val)
{
int unit = memcg_page_state_unit(idx);
if (!val || unit == PAGE_SIZE)
return val;
else
return max(val * unit / PAGE_SIZE, 1UL);
}
/**
* __mod_memcg_state - update cgroup memory statistics
* @memcg: the memory cgroup
* @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
* @val: delta to add to the counter, can be negative
*/
void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val)
{
if (mem_cgroup_disabled())
return;
__this_cpu_add(memcg->vmstats_percpu->state[idx], val);
memcg_rstat_updated(memcg, memcg_state_val_in_pages(idx, val));
}
/* idx can be of type enum memcg_stat_item or node_stat_item. */
static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
{
long x = READ_ONCE(memcg->vmstats->state_local[idx]);
#ifdef CONFIG_SMP
if (x < 0)
x = 0;
#endif
return x;
}
void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
int val)
{
struct mem_cgroup_per_node *pn;
struct mem_cgroup *memcg;
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
memcg = pn->memcg;
/*
* The caller from rmap relies on disabled preemption because they never
* update their counter from in-interrupt context. For these two
* counters we check that the update is never performed from an
* interrupt context while other caller need to have disabled interrupt.
*/
__memcg_stats_lock();
if (IS_ENABLED(CONFIG_DEBUG_VM)) {
switch (idx) {
case NR_ANON_MAPPED:
case NR_FILE_MAPPED:
case NR_ANON_THPS:
case NR_SHMEM_PMDMAPPED:
case NR_FILE_PMDMAPPED:
WARN_ON_ONCE(!in_task());
break;
default:
VM_WARN_ON_IRQS_ENABLED();
}
}
/* Update memcg */
__this_cpu_add(memcg->vmstats_percpu->state[idx], val);
/* Update lruvec */
__this_cpu_add(pn->lruvec_stats_percpu->state[idx], val);
memcg_rstat_updated(memcg, memcg_state_val_in_pages(idx, val));
memcg_stats_unlock();
}
/**
* __mod_lruvec_state - update lruvec memory statistics
* @lruvec: the lruvec
* @idx: the stat item
* @val: delta to add to the counter, can be negative
*
* The lruvec is the intersection of the NUMA node and a cgroup. This
* function updates the all three counters that are affected by a
* change of state at this level: per-node, per-cgroup, per-lruvec.
*/
void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
int val)
{
/* Update node */
__mod_node_page_state(lruvec_pgdat(lruvec), idx, val);
/* Update memcg and lruvec */
if (!mem_cgroup_disabled())
__mod_memcg_lruvec_state(lruvec, idx, val);
}
void __lruvec_stat_mod_folio(struct folio *folio, enum node_stat_item idx,
int val)
{
struct mem_cgroup *memcg;
pg_data_t *pgdat = folio_pgdat(folio);
struct lruvec *lruvec;
rcu_read_lock();
memcg = folio_memcg(folio);
/* Untracked pages have no memcg, no lruvec. Update only the node */
if (!memcg) {
rcu_read_unlock();
__mod_node_page_state(pgdat, idx, val);
return;
}
lruvec = mem_cgroup_lruvec(memcg, pgdat);
__mod_lruvec_state(lruvec, idx, val);
rcu_read_unlock();
}
EXPORT_SYMBOL(__lruvec_stat_mod_folio);
void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)
{
pg_data_t *pgdat = page_pgdat(virt_to_page(p));
struct mem_cgroup *memcg;
struct lruvec *lruvec;
rcu_read_lock();
memcg = mem_cgroup_from_slab_obj(p);
/*
* Untracked pages have no memcg, no lruvec. Update only the
* node. If we reparent the slab objects to the root memcg,
* when we free the slab object, we need to update the per-memcg
* vmstats to keep it correct for the root memcg.
*/
if (!memcg) {
__mod_node_page_state(pgdat, idx, val);
} else {
lruvec = mem_cgroup_lruvec(memcg, pgdat);
__mod_lruvec_state(lruvec, idx, val);
}
rcu_read_unlock();
}
/**
* __count_memcg_events - account VM events in a cgroup
* @memcg: the memory cgroup
* @idx: the event item
* @count: the number of events that occurred
*/
void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
unsigned long count)
{
int index = memcg_events_index(idx);
if (mem_cgroup_disabled() || index < 0)
return;
memcg_stats_lock();
__this_cpu_add(memcg->vmstats_percpu->events[index], count);
memcg_rstat_updated(memcg, count);
memcg_stats_unlock();
}
static unsigned long memcg_events(struct mem_cgroup *memcg, int event)
{
int index = memcg_events_index(event);
if (index < 0)
return 0;
return READ_ONCE(memcg->vmstats->events[index]);
}
static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
{
int index = memcg_events_index(event);
if (index < 0)
return 0;
return READ_ONCE(memcg->vmstats->events_local[index]);
}
static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
int nr_pages)
{
/* pagein of a big page is an event. So, ignore page size */
if (nr_pages > 0)
__count_memcg_events(memcg, PGPGIN, 1);
else {
__count_memcg_events(memcg, PGPGOUT, 1);
nr_pages = -nr_pages; /* for event */
}
__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
}
static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
enum mem_cgroup_events_target target)
{
unsigned long val, next;
val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
/* from time_after() in jiffies.h */
if ((long)(next - val) < 0) {
switch (target) {
case MEM_CGROUP_TARGET_THRESH:
next = val + THRESHOLDS_EVENTS_TARGET;
break;
case MEM_CGROUP_TARGET_SOFTLIMIT:
next = val + SOFTLIMIT_EVENTS_TARGET;
break;
default:
break;
}
__this_cpu_write(memcg->vmstats_percpu->targets[target], next);
return true;
}
return false;
}
/*
* Check events in order.
*
*/
static void memcg_check_events(struct mem_cgroup *memcg, int nid)
{
if (IS_ENABLED(CONFIG_PREEMPT_RT))
return;
/* threshold event is triggered in finer grain than soft limit */
if (unlikely(mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_THRESH))) {
bool do_softlimit;
do_softlimit = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_SOFTLIMIT);
mem_cgroup_threshold(memcg);
if (unlikely(do_softlimit))
mem_cgroup_update_tree(memcg, nid);
}
}
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
{
/*
* mm_update_next_owner() may clear mm->owner to NULL
* if it races with swapoff, page migration, etc.
* So this can be called with p == NULL.
*/
if (unlikely(!p))
return NULL;
return mem_cgroup_from_css(task_css(p, memory_cgrp_id));
}
EXPORT_SYMBOL(mem_cgroup_from_task);
static __always_inline struct mem_cgroup *active_memcg(void)
{
if (!in_task())
return this_cpu_read(int_active_memcg);
else
return current->active_memcg;
}
/**
* get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg.
* @mm: mm from which memcg should be extracted. It can be NULL.
*
* Obtain a reference on mm->memcg and returns it if successful. If mm
* is NULL, then the memcg is chosen as follows:
* 1) The active memcg, if set.
* 2) current->mm->memcg, if available
* 3) root memcg
* If mem_cgroup is disabled, NULL is returned.
*/
struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
{
struct mem_cgroup *memcg;
if (mem_cgroup_disabled())
return NULL;
/*
* Page cache insertions can happen without an
* actual mm context, e.g. during disk probing
* on boot, loopback IO, acct() writes etc.
*
* No need to css_get on root memcg as the reference
* counting is disabled on the root level in the
* cgroup core. See CSS_NO_REF.
*/
if (unlikely(!mm)) {
memcg = active_memcg();
if (unlikely(memcg)) {
/* remote memcg must hold a ref */
css_get(&memcg->css);
return memcg;
}
mm = current->mm;
if (unlikely(!mm))
return root_mem_cgroup;
}
rcu_read_lock();
do {
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))
memcg = root_mem_cgroup;
} while (!css_tryget(&memcg->css));
rcu_read_unlock();
return memcg;
}
EXPORT_SYMBOL(get_mem_cgroup_from_mm);
/**
* get_mem_cgroup_from_current - Obtain a reference on current task's memcg.
*/
struct mem_cgroup *get_mem_cgroup_from_current(void)
{
struct mem_cgroup *memcg;
if (mem_cgroup_disabled())
return NULL;
again:
rcu_read_lock();
memcg = mem_cgroup_from_task(current);
if (!css_tryget(&memcg->css)) {
rcu_read_unlock();
goto again;
}
rcu_read_unlock();
return memcg;
}
/**
* mem_cgroup_iter - iterate over memory cgroup hierarchy
* @root: hierarchy root
* @prev: previously returned memcg, NULL on first invocation
* @reclaim: cookie for shared reclaim walks, NULL for full walks
*
* Returns references to children of the hierarchy below @root, or
* @root itself, or %NULL after a full round-trip.
*
* Caller must pass the return value in @prev on subsequent
* invocations for reference counting, or use mem_cgroup_iter_break()
* to cancel a hierarchy walk before the round-trip is complete.
*
* Reclaimers can specify a node in @reclaim to divide up the memcgs
* in the hierarchy among all concurrent reclaimers operating on the
* same node.
*/
struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
struct mem_cgroup *prev,
struct mem_cgroup_reclaim_cookie *reclaim)
{
struct mem_cgroup_reclaim_iter *iter;
struct cgroup_subsys_state *css = NULL;
struct mem_cgroup *memcg = NULL;
struct mem_cgroup *pos = NULL;
if (mem_cgroup_disabled())
return NULL;
if (!root)
root = root_mem_cgroup;
rcu_read_lock();
if (reclaim) {
struct mem_cgroup_per_node *mz;
mz = root->nodeinfo[reclaim->pgdat->node_id];
iter = &mz->iter;
/*
* On start, join the current reclaim iteration cycle.
* Exit when a concurrent walker completes it.
*/
if (!prev)
reclaim->generation = iter->generation;
else if (reclaim->generation != iter->generation)
goto out_unlock;
while (1) {
pos = READ_ONCE(iter->position);
if (!pos || css_tryget(&pos->css))
break;
/*
* css reference reached zero, so iter->position will
* be cleared by ->css_released. However, we should not
* rely on this happening soon, because ->css_released
* is called from a work queue, and by busy-waiting we
* might block it. So we clear iter->position right
* away.
*/
(void)cmpxchg(&iter->position, pos, NULL);
}
} else if (prev) {
pos = prev;
}
if (pos)
css = &pos->css;
for (;;) {
css = css_next_descendant_pre(css, &root->css);
if (!css) {
/*
* Reclaimers share the hierarchy walk, and a
* new one might jump in right at the end of
* the hierarchy - make sure they see at least
* one group and restart from the beginning.
*/
if (!prev)
continue;
break;
}
/*
* Verify the css and acquire a reference. The root
* is provided by the caller, so we know it's alive
* and kicking, and don't take an extra reference.
*/
if (css == &root->css || css_tryget(css)) {
memcg = mem_cgroup_from_css(css);
break;
}
}
if (reclaim) {
/*
* The position could have already been updated by a competing
* thread, so check that the value hasn't changed since we read
* it to avoid reclaiming from the same cgroup twice.
*/
(void)cmpxchg(&iter->position, pos, memcg);
if (pos)
css_put(&pos->css);
if (!memcg)
iter->generation++;
}
out_unlock:
rcu_read_unlock();
if (prev && prev != root)
css_put(&prev->css);
return memcg;
}
/**
* mem_cgroup_iter_break - abort a hierarchy walk prematurely
* @root: hierarchy root
* @prev: last visited hierarchy member as returned by mem_cgroup_iter()
*/
void mem_cgroup_iter_break(struct mem_cgroup *root,
struct mem_cgroup *prev)
{
if (!root)
root = root_mem_cgroup;
if (prev && prev != root)
css_put(&prev->css);
}
static void __invalidate_reclaim_iterators(struct mem_cgroup *from,
struct mem_cgroup *dead_memcg)
{
struct mem_cgroup_reclaim_iter *iter;
struct mem_cgroup_per_node *mz;
int nid;
for_each_node(nid) {
mz = from->nodeinfo[nid];
iter = &mz->iter;
cmpxchg(&iter->position, dead_memcg, NULL);
}
}
static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
{
struct mem_cgroup *memcg = dead_memcg;
struct mem_cgroup *last;
do {
__invalidate_reclaim_iterators(memcg, dead_memcg);
last = memcg;
} while ((memcg = parent_mem_cgroup(memcg)));
/*
* When cgroup1 non-hierarchy mode is used,
* parent_mem_cgroup() does not walk all the way up to the
* cgroup root (root_mem_cgroup). So we have to handle
* dead_memcg from cgroup root separately.
*/
if (!mem_cgroup_is_root(last))
__invalidate_reclaim_iterators(root_mem_cgroup,
dead_memcg);
}
/**
* mem_cgroup_scan_tasks - iterate over tasks of a memory cgroup hierarchy
* @memcg: hierarchy root
* @fn: function to call for each task
* @arg: argument passed to @fn
*
* This function iterates over tasks attached to @memcg or to any of its
* descendants and calls @fn for each task. If @fn returns a non-zero
* value, the function breaks the iteration loop. Otherwise, it will iterate
* over all tasks and return 0.
*
* This function must not be called for the root memory cgroup.
*/
void mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
int (*fn)(struct task_struct *, void *), void *arg)
{
struct mem_cgroup *iter;
int ret = 0;
BUG_ON(mem_cgroup_is_root(memcg));
for_each_mem_cgroup_tree(iter, memcg) {
struct css_task_iter it;
struct task_struct *task;
css_task_iter_start(&iter->css, CSS_TASK_ITER_PROCS, &it);
while (!ret && (task = css_task_iter_next(&it)))
ret = fn(task, arg);
css_task_iter_end(&it);
if (ret) {
mem_cgroup_iter_break(memcg, iter);
break;
}
}
}
#ifdef CONFIG_DEBUG_VM
void lruvec_memcg_debug(struct lruvec *lruvec, struct folio *folio)
{
struct mem_cgroup *memcg;
if (mem_cgroup_disabled())
return;
memcg = folio_memcg(folio);
if (!memcg)
VM_BUG_ON_FOLIO(!mem_cgroup_is_root(lruvec_memcg(lruvec)), folio);
else
VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != memcg, folio);
}
#endif
/**
* folio_lruvec_lock - Lock the lruvec for a folio.
* @folio: Pointer to the folio.
*
* These functions are safe to use under any of the following conditions:
* - folio locked
* - folio_test_lru false
* - folio_memcg_lock()
* - folio frozen (refcount of 0)
*
* Return: The lruvec this folio is on with its lock held.
*/
struct lruvec *folio_lruvec_lock(struct folio *folio)
{
struct lruvec *lruvec = folio_lruvec(folio);
spin_lock(&lruvec->lru_lock);
lruvec_memcg_debug(lruvec, folio);
return lruvec;
}
/**
* folio_lruvec_lock_irq - Lock the lruvec for a folio.
* @folio: Pointer to the folio.
*
* These functions are safe to use under any of the following conditions:
* - folio locked
* - folio_test_lru false
* - folio_memcg_lock()
* - folio frozen (refcount of 0)
*
* Return: The lruvec this folio is on with its lock held and interrupts
* disabled.
*/
struct lruvec *folio_lruvec_lock_irq(struct folio *folio)
{
struct lruvec *lruvec = folio_lruvec(folio);
spin_lock_irq(&lruvec->lru_lock);
lruvec_memcg_debug(lruvec, folio);
return lruvec;
}
/**
* folio_lruvec_lock_irqsave - Lock the lruvec for a folio.
* @folio: Pointer to the folio.
* @flags: Pointer to irqsave flags.
*
* These functions are safe to use under any of the following conditions:
* - folio locked
* - folio_test_lru false
* - folio_memcg_lock()
* - folio frozen (refcount of 0)
*
* Return: The lruvec this folio is on with its lock held and interrupts
* disabled.
*/
struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio,
unsigned long *flags)
{
struct lruvec *lruvec = folio_lruvec(folio);
spin_lock_irqsave(&lruvec->lru_lock, *flags);
lruvec_memcg_debug(lruvec, folio);
return lruvec;
}
/**
* mem_cgroup_update_lru_size - account for adding or removing an lru page
* @lruvec: mem_cgroup per zone lru vector
* @lru: index of lru list the page is sitting on
* @zid: zone id of the accounted pages
* @nr_pages: positive when adding or negative when removing
*
* This function must be called under lru_lock, just before a page is added
* to or just after a page is removed from an lru list.
*/
void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
int zid, int nr_pages)
{
struct mem_cgroup_per_node *mz;
unsigned long *lru_size;
long size;
if (mem_cgroup_disabled())
return;
mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
lru_size = &mz->lru_zone_size[zid][lru];
if (nr_pages < 0)
*lru_size += nr_pages;
size = *lru_size;
if (WARN_ONCE(size < 0,
"%s(%p, %d, %d): lru_size %ld\n",
__func__, lruvec, lru, nr_pages, size)) {
VM_BUG_ON(1);
*lru_size = 0;
}
if (nr_pages > 0)
*lru_size += nr_pages;
}
/**
* mem_cgroup_margin - calculate chargeable space of a memory cgroup
* @memcg: the memory cgroup
*
* Returns the maximum amount of memory @mem can be charged with, in
* pages.
*/
static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
{
unsigned long margin = 0;
unsigned long count;
unsigned long limit;
count = page_counter_read(&memcg->memory);
limit = READ_ONCE(memcg->memory.max);
if (count < limit)
margin = limit - count;
if (do_memsw_account()) {
count = page_counter_read(&memcg->memsw);
limit = READ_ONCE(memcg->memsw.max);
if (count < limit)
margin = min(margin, limit - count);
else
margin = 0;
}
return margin;
}
/*
* A routine for checking "mem" is under move_account() or not.
*
* Checking a cgroup is mc.from or mc.to or under hierarchy of
* moving cgroups. This is for waiting at high-memory pressure
* caused by "move".
*/
static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
{
struct mem_cgroup *from;
struct mem_cgroup *to;
bool ret = false;
/*
* Unlike task_move routines, we access mc.to, mc.from not under
* mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
*/
spin_lock(&mc.lock);
from = mc.from;
to = mc.to;
if (!from)
goto unlock;
ret = mem_cgroup_is_descendant(from, memcg) ||
mem_cgroup_is_descendant(to, memcg);
unlock:
spin_unlock(&mc.lock);
return ret;
}
static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
{
if (mc.moving_task && current != mc.moving_task) {
if (mem_cgroup_under_move(memcg)) {
DEFINE_WAIT(wait);
prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
/* moving charge context might have finished. */
if (mc.moving_task)
schedule();
finish_wait(&mc.waitq, &wait);
return true;
}
}
return false;
}
struct memory_stat {
const char *name;
unsigned int idx;
};
static const struct memory_stat memory_stats[] = {
{ "anon", NR_ANON_MAPPED },
{ "file", NR_FILE_PAGES },
{ "kernel", MEMCG_KMEM },
{ "kernel_stack", NR_KERNEL_STACK_KB },
{ "pagetables", NR_PAGETABLE },
{ "sec_pagetables", NR_SECONDARY_PAGETABLE },
{ "percpu", MEMCG_PERCPU_B },
{ "sock", MEMCG_SOCK },
{ "vmalloc", MEMCG_VMALLOC },
{ "shmem", NR_SHMEM },
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
{ "zswap", MEMCG_ZSWAP_B },
{ "zswapped", MEMCG_ZSWAPPED },
#endif
{ "file_mapped", NR_FILE_MAPPED },
{ "file_dirty", NR_FILE_DIRTY },
{ "file_writeback", NR_WRITEBACK },
#ifdef CONFIG_SWAP
{ "swapcached", NR_SWAPCACHE },
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
{ "anon_thp", NR_ANON_THPS },
{ "file_thp", NR_FILE_THPS },
{ "shmem_thp", NR_SHMEM_THPS },
#endif
{ "inactive_anon", NR_INACTIVE_ANON },
{ "active_anon", NR_ACTIVE_ANON },
{ "inactive_file", NR_INACTIVE_FILE },
{ "active_file", NR_ACTIVE_FILE },
{ "unevictable", NR_UNEVICTABLE },
{ "slab_reclaimable", NR_SLAB_RECLAIMABLE_B },
{ "slab_unreclaimable", NR_SLAB_UNRECLAIMABLE_B },
/* The memory events */
{ "workingset_refault_anon", WORKINGSET_REFAULT_ANON },
{ "workingset_refault_file", WORKINGSET_REFAULT_FILE },
{ "workingset_activate_anon", WORKINGSET_ACTIVATE_ANON },
{ "workingset_activate_file", WORKINGSET_ACTIVATE_FILE },
{ "workingset_restore_anon", WORKINGSET_RESTORE_ANON },
{ "workingset_restore_file", WORKINGSET_RESTORE_FILE },
{ "workingset_nodereclaim", WORKINGSET_NODERECLAIM },
};
/* The actual unit of the state item, not the same as the output unit */
static int memcg_page_state_unit(int item)
{
switch (item) {
case MEMCG_PERCPU_B:
case MEMCG_ZSWAP_B:
case NR_SLAB_RECLAIMABLE_B:
case NR_SLAB_UNRECLAIMABLE_B:
return 1;
case NR_KERNEL_STACK_KB:
return SZ_1K;
default:
return PAGE_SIZE;
}
}
/* Translate stat items to the correct unit for memory.stat output */
static int memcg_page_state_output_unit(int item)
{
/*
* Workingset state is actually in pages, but we export it to userspace
* as a scalar count of events, so special case it here.
*/
switch (item) {
case WORKINGSET_REFAULT_ANON:
case WORKINGSET_REFAULT_FILE:
case WORKINGSET_ACTIVATE_ANON:
case WORKINGSET_ACTIVATE_FILE:
case WORKINGSET_RESTORE_ANON:
case WORKINGSET_RESTORE_FILE:
case WORKINGSET_NODERECLAIM:
return 1;
default:
return memcg_page_state_unit(item);
}
}
static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg,
int item)
{
return memcg_page_state(memcg, item) *
memcg_page_state_output_unit(item);
}
static inline unsigned long memcg_page_state_local_output(
struct mem_cgroup *memcg, int item)
{
return memcg_page_state_local(memcg, item) *
memcg_page_state_output_unit(item);
}
static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
{
int i;
/*
* Provide statistics on the state of the memory subsystem as
* well as cumulative event counters that show past behavior.
*
* This list is ordered following a combination of these gradients:
* 1) generic big picture -> specifics and details
* 2) reflecting userspace activity -> reflecting kernel heuristics
*
* Current memory state:
*/
mem_cgroup_flush_stats(memcg);
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
u64 size;
size = memcg_page_state_output(memcg, memory_stats[i].idx);
seq_buf_printf(s, "%s %llu\n", memory_stats[i].name, size);
if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) {
size += memcg_page_state_output(memcg,
NR_SLAB_RECLAIMABLE_B);
seq_buf_printf(s, "slab %llu\n", size);
}
}
/* Accumulated memory events */
seq_buf_printf(s, "pgscan %lu\n",
memcg_events(memcg, PGSCAN_KSWAPD) +
memcg_events(memcg, PGSCAN_DIRECT) +
memcg_events(memcg, PGSCAN_KHUGEPAGED));
seq_buf_printf(s, "pgsteal %lu\n",
memcg_events(memcg, PGSTEAL_KSWAPD) +
memcg_events(memcg, PGSTEAL_DIRECT) +
memcg_events(memcg, PGSTEAL_KHUGEPAGED));
for (i = 0; i < ARRAY_SIZE(memcg_vm_event_stat); i++) {
if (memcg_vm_event_stat[i] == PGPGIN ||
memcg_vm_event_stat[i] == PGPGOUT)
continue;
seq_buf_printf(s, "%s %lu\n",
vm_event_name(memcg_vm_event_stat[i]),
memcg_events(memcg, memcg_vm_event_stat[i]));
}
/* The above should easily fit into one page */
WARN_ON_ONCE(seq_buf_has_overflowed(s));
}
static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
static void memory_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
{
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
memcg_stat_format(memcg, s);
else
memcg1_stat_format(memcg, s);
WARN_ON_ONCE(seq_buf_has_overflowed(s));
}
/**
* mem_cgroup_print_oom_context: Print OOM information relevant to
* memory controller.
* @memcg: The memory cgroup that went over limit
* @p: Task that is going to be killed
*
* NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
* enabled
*/
void mem_cgroup_print_oom_context(struct mem_cgroup *memcg, struct task_struct *p)
{
rcu_read_lock();
if (memcg) {
pr_cont(",oom_memcg=");
pr_cont_cgroup_path(memcg->css.cgroup);
} else
pr_cont(",global_oom");
if (p) {
pr_cont(",task_memcg=");
pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
}
rcu_read_unlock();
}
/**
* mem_cgroup_print_oom_meminfo: Print OOM memory information relevant to
* memory controller.
* @memcg: The memory cgroup that went over limit
*/
void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
{
/* Use static buffer, for the caller is holding oom_lock. */
static char buf[PAGE_SIZE];
struct seq_buf s;
lockdep_assert_held(&oom_lock);
pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memory)),
K((u64)READ_ONCE(memcg->memory.max)), memcg->memory.failcnt);
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->swap)),
K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt);
else {
pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memsw)),
K((u64)memcg->memsw.max), memcg->memsw.failcnt);
pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->kmem)),
K((u64)memcg->kmem.max), memcg->kmem.failcnt);
}
pr_info("Memory cgroup stats for ");
pr_cont_cgroup_path(memcg->css.cgroup);
pr_cont(":");
seq_buf_init(&s, buf, sizeof(buf));
memory_stat_format(memcg, &s);
seq_buf_do_printk(&s, KERN_INFO);
}
/*
* Return the memory (and swap, if configured) limit for a memcg.
*/
unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
{
unsigned long max = READ_ONCE(memcg->memory.max);
if (do_memsw_account()) {
if (mem_cgroup_swappiness(memcg)) {
/* Calculate swap excess capacity from memsw limit */
unsigned long swap = READ_ONCE(memcg->memsw.max) - max;
max += min(swap, (unsigned long)total_swap_pages);
}
} else {
if (mem_cgroup_swappiness(memcg))
max += min(READ_ONCE(memcg->swap.max),
(unsigned long)total_swap_pages);
}
return max;
}
unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
{
return page_counter_read(&memcg->memory);
}
static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
int order)
{
struct oom_control oc = {
.zonelist = NULL,
.nodemask = NULL,
.memcg = memcg,
.gfp_mask = gfp_mask,
.order = order,
};
bool ret = true;
if (mutex_lock_killable(&oom_lock))
return true;
if (mem_cgroup_margin(memcg) >= (1 << order))
goto unlock;
/*
* A few threads which were not waiting at mutex_lock_killable() can
* fail to bail out. Therefore, check again after holding oom_lock.
*/
ret = task_is_dying() || out_of_memory(&oc);
unlock:
mutex_unlock(&oom_lock);
return ret;
}
static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
pg_data_t *pgdat,
gfp_t gfp_mask,
unsigned long *total_scanned)
{
struct mem_cgroup *victim = NULL;
int total = 0;
int loop = 0;
unsigned long excess;
unsigned long nr_scanned;
struct mem_cgroup_reclaim_cookie reclaim = {
.pgdat = pgdat,
};
excess = soft_limit_excess(root_memcg);
while (1) {
victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
if (!victim) {
loop++;
if (loop >= 2) {
/*
* If we have not been able to reclaim
* anything, it might because there are
* no reclaimable pages under this hierarchy
*/
if (!total)
break;
/*
* We want to do more targeted reclaim.
* excess >> 2 is not to excessive so as to
* reclaim too much, nor too less that we keep
* coming back to reclaim from this cgroup
*/
if (total >= (excess >> 2) ||
(loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
break;
}
continue;
}
total += mem_cgroup_shrink_node(victim, gfp_mask, false,
pgdat, &nr_scanned);
*total_scanned += nr_scanned;
if (!soft_limit_excess(root_memcg))
break;
}
mem_cgroup_iter_break(root_memcg, victim);
return total;
}
#ifdef CONFIG_LOCKDEP
static struct lockdep_map memcg_oom_lock_dep_map = {
.name = "memcg_oom_lock",
};
#endif
static DEFINE_SPINLOCK(memcg_oom_lock);
/*
* Check OOM-Killer is already running under our hierarchy.
* If someone is running, return false.
*/
static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter, *failed = NULL;
spin_lock(&memcg_oom_lock);
for_each_mem_cgroup_tree(iter, memcg) {
if (iter->oom_lock) {
/*
* this subtree of our hierarchy is already locked
* so we cannot give a lock.
*/
failed = iter;
mem_cgroup_iter_break(memcg, iter);
break;
} else
iter->oom_lock = true;
}
if (failed) {
/*
* OK, we failed to lock the whole subtree so we have
* to clean up what we set up to the failing subtree
*/
for_each_mem_cgroup_tree(iter, memcg) {
if (iter == failed) {
mem_cgroup_iter_break(memcg, iter);
break;
}
iter->oom_lock = false;
}
} else
mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
spin_unlock(&memcg_oom_lock);
return !failed;
}
static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
spin_lock(&memcg_oom_lock);
mutex_release(&memcg_oom_lock_dep_map, _RET_IP_);
for_each_mem_cgroup_tree(iter, memcg)
iter->oom_lock = false;
spin_unlock(&memcg_oom_lock);
}
static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
spin_lock(&memcg_oom_lock);
for_each_mem_cgroup_tree(iter, memcg)
iter->under_oom++;
spin_unlock(&memcg_oom_lock);
}
static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
/*
* Be careful about under_oom underflows because a child memcg
* could have been added after mem_cgroup_mark_under_oom.
*/
spin_lock(&memcg_oom_lock);
for_each_mem_cgroup_tree(iter, memcg)
if (iter->under_oom > 0)
iter->under_oom--;
spin_unlock(&memcg_oom_lock);
}
static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
struct oom_wait_info {
struct mem_cgroup *memcg;
wait_queue_entry_t wait;
};
static int memcg_oom_wake_function(wait_queue_entry_t *wait,
unsigned mode, int sync, void *arg)
{
struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
struct mem_cgroup *oom_wait_memcg;
struct oom_wait_info *oom_wait_info;
oom_wait_info = container_of(wait, struct oom_wait_info, wait);
oom_wait_memcg = oom_wait_info->memcg;
if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
!mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
return 0;
return autoremove_wake_function(wait, mode, sync, arg);
}
static void memcg_oom_recover(struct mem_cgroup *memcg)
{
/*
* For the following lockless ->under_oom test, the only required
* guarantee is that it must see the state asserted by an OOM when
* this function is called as a result of userland actions
* triggered by the notification of the OOM. This is trivially
* achieved by invoking mem_cgroup_mark_under_oom() before
* triggering notification.
*/
if (memcg && memcg->under_oom)
__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
}
/*
* Returns true if successfully killed one or more processes. Though in some
* corner cases it can return true even without killing any process.
*/
static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
{
bool locked, ret;
if (order > PAGE_ALLOC_COSTLY_ORDER)
return false;
memcg_memory_event(memcg, MEMCG_OOM);
/*
* We are in the middle of the charge context here, so we
* don't want to block when potentially sitting on a callstack
* that holds all kinds of filesystem and mm locks.
*
* cgroup1 allows disabling the OOM killer and waiting for outside
* handling until the charge can succeed; remember the context and put
* the task to sleep at the end of the page fault when all locks are
* released.
*
* On the other hand, in-kernel OOM killer allows for an async victim
* memory reclaim (oom_reaper) and that means that we are not solely
* relying on the oom victim to make a forward progress and we can
* invoke the oom killer here.
*
* Please note that mem_cgroup_out_of_memory might fail to find a
* victim and then we have to bail out from the charge path.
*/
if (READ_ONCE(memcg->oom_kill_disable)) {
if (current->in_user_fault) {
css_get(&memcg->css);
current->memcg_in_oom = memcg;
current->memcg_oom_gfp_mask = mask;
current->memcg_oom_order = order;
}
return false;
}
mem_cgroup_mark_under_oom(memcg);
locked = mem_cgroup_oom_trylock(memcg);
if (locked)
mem_cgroup_oom_notify(memcg);
mem_cgroup_unmark_under_oom(memcg);
ret = mem_cgroup_out_of_memory(memcg, mask, order);
if (locked)
mem_cgroup_oom_unlock(memcg);
return ret;
}
/**
* mem_cgroup_oom_synchronize - complete memcg OOM handling
* @handle: actually kill/wait or just clean up the OOM state
*
* This has to be called at the end of a page fault if the memcg OOM
* handler was enabled.
*
* Memcg supports userspace OOM handling where failed allocations must
* sleep on a waitqueue until the userspace task resolves the
* situation. Sleeping directly in the charge context with all kinds
* of locks held is not a good idea, instead we remember an OOM state
* in the task and mem_cgroup_oom_synchronize() has to be called at
* the end of the page fault to complete the OOM handling.
*
* Returns %true if an ongoing memcg OOM situation was detected and
* completed, %false otherwise.
*/
bool mem_cgroup_oom_synchronize(bool handle)
{
struct mem_cgroup *memcg = current->memcg_in_oom;
struct oom_wait_info owait;
bool locked;
/* OOM is global, do not handle */
if (!memcg)
return false;
if (!handle)
goto cleanup;
owait.memcg = memcg;
owait.wait.flags = 0;
owait.wait.func = memcg_oom_wake_function;
owait.wait.private = current;
INIT_LIST_HEAD(&owait.wait.entry);
prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
mem_cgroup_mark_under_oom(memcg);
locked = mem_cgroup_oom_trylock(memcg);
if (locked)
mem_cgroup_oom_notify(memcg);
schedule();
mem_cgroup_unmark_under_oom(memcg);
finish_wait(&memcg_oom_waitq, &owait.wait);
if (locked)
mem_cgroup_oom_unlock(memcg);
cleanup:
current->memcg_in_oom = NULL;
css_put(&memcg->css);
return true;
}
/**
* mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM
* @victim: task to be killed by the OOM killer
* @oom_domain: memcg in case of memcg OOM, NULL in case of system-wide OOM
*
* Returns a pointer to a memory cgroup, which has to be cleaned up
* by killing all belonging OOM-killable tasks.
*
* Caller has to call mem_cgroup_put() on the returned non-NULL memcg.
*/
struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
struct mem_cgroup *oom_domain)
{
struct mem_cgroup *oom_group = NULL;
struct mem_cgroup *memcg;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
return NULL;
if (!oom_domain)
oom_domain = root_mem_cgroup;
rcu_read_lock();
memcg = mem_cgroup_from_task(victim);
if (mem_cgroup_is_root(memcg))
goto out;
/*
* If the victim task has been asynchronously moved to a different
* memory cgroup, we might end up killing tasks outside oom_domain.
* In this case it's better to ignore memory.group.oom.
*/
if (unlikely(!mem_cgroup_is_descendant(memcg, oom_domain)))
goto out;
/*
* Traverse the memory cgroup hierarchy from the victim task's
* cgroup up to the OOMing cgroup (or root) to find the
* highest-level memory cgroup with oom.group set.
*/
for (; memcg; memcg = parent_mem_cgroup(memcg)) {
if (READ_ONCE(memcg->oom_group))
oom_group = memcg;
if (memcg == oom_domain)
break;
}
if (oom_group)
css_get(&oom_group->css);
out:
rcu_read_unlock();
return oom_group;
}
void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)
{
pr_info("Tasks in ");
pr_cont_cgroup_path(memcg->css.cgroup);
pr_cont(" are going to be killed due to memory.oom.group set\n");
}
/**
* folio_memcg_lock - Bind a folio to its memcg.
* @folio: The folio.
*
* This function prevents unlocked LRU folios from being moved to
* another cgroup.
*
* It ensures lifetime of the bound memcg. The caller is responsible
* for the lifetime of the folio.
*/
void folio_memcg_lock(struct folio *folio)
{
struct mem_cgroup *memcg;
unsigned long flags;
/*
* The RCU lock is held throughout the transaction. The fast
* path can get away without acquiring the memcg->move_lock
* because page moving starts with an RCU grace period.
*/
rcu_read_lock();
if (mem_cgroup_disabled())
return;
again:
memcg = folio_memcg(folio);
if (unlikely(!memcg))
return;
#ifdef CONFIG_PROVE_LOCKING
local_irq_save(flags);
might_lock(&memcg->move_lock);
local_irq_restore(flags);
#endif
if (atomic_read(&memcg->moving_account) <= 0)
return;
spin_lock_irqsave(&memcg->move_lock, flags);
if (memcg != folio_memcg(folio)) {
spin_unlock_irqrestore(&memcg->move_lock, flags);
goto again;
}
/*
* When charge migration first begins, we can have multiple
* critical sections holding the fast-path RCU lock and one
* holding the slowpath move_lock. Track the task who has the
* move_lock for folio_memcg_unlock().
*/
memcg->move_lock_task = current;
memcg->move_lock_flags = flags;
}
static void __folio_memcg_unlock(struct mem_cgroup *memcg)
{
if (memcg && memcg->move_lock_task == current) {
unsigned long flags = memcg->move_lock_flags;
memcg->move_lock_task = NULL;
memcg->move_lock_flags = 0;
spin_unlock_irqrestore(&memcg->move_lock, flags);
}
rcu_read_unlock();
}
/**
* folio_memcg_unlock - Release the binding between a folio and its memcg.
* @folio: The folio.
*
* This releases the binding created by folio_memcg_lock(). This does
* not change the accounting of this folio to its memcg, but it does
* permit others to change it.
*/
void folio_memcg_unlock(struct folio *folio)
{
__folio_memcg_unlock(folio_memcg(folio));
}
struct memcg_stock_pcp {
local_lock_t stock_lock;
struct mem_cgroup *cached; /* this never be root cgroup */
unsigned int nr_pages;
#ifdef CONFIG_MEMCG_KMEM
struct obj_cgroup *cached_objcg;
struct pglist_data *cached_pgdat;
unsigned int nr_bytes;
int nr_slab_reclaimable_b;
int nr_slab_unreclaimable_b;
#endif
struct work_struct work;
unsigned long flags;
#define FLUSHING_CACHED_CHARGE 0
};
static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = {
.stock_lock = INIT_LOCAL_LOCK(stock_lock),
};
static DEFINE_MUTEX(percpu_charge_mutex);
#ifdef CONFIG_MEMCG_KMEM
static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock);
static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
struct mem_cgroup *root_memcg);
static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages);
#else
static inline struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock)
{
return NULL;
}
static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
struct mem_cgroup *root_memcg)
{
return false;
}
static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
{
}
#endif
/**
* consume_stock: Try to consume stocked charge on this cpu.
* @memcg: memcg to consume from.
* @nr_pages: how many pages to charge.
*
* The charges will only happen if @memcg matches the current cpu's memcg
* stock, and at least @nr_pages are available in that stock. Failure to
* service an allocation will refill the stock.
*
* returns true if successful, false otherwise.
*/
static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
{
struct memcg_stock_pcp *stock;
unsigned long flags;
bool ret = false;
if (nr_pages > MEMCG_CHARGE_BATCH)
return ret;
local_lock_irqsave(&memcg_stock.stock_lock, flags);
stock = this_cpu_ptr(&memcg_stock);
if (memcg == READ_ONCE(stock->cached) && stock->nr_pages >= nr_pages) {
stock->nr_pages -= nr_pages;
ret = true;
}
local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
return ret;
}
/*
* Returns stocks cached in percpu and reset cached information.
*/
static void drain_stock(struct memcg_stock_pcp *stock)
{
struct mem_cgroup *old = READ_ONCE(stock->cached);
if (!old)
return;
if (stock->nr_pages) {
page_counter_uncharge(&old->memory, stock->nr_pages);
if (do_memsw_account())
page_counter_uncharge(&old->memsw, stock->nr_pages);
stock->nr_pages = 0;
}
css_put(&old->css);
WRITE_ONCE(stock->cached, NULL);
}
static void drain_local_stock(struct work_struct *dummy)
{
struct memcg_stock_pcp *stock;
struct obj_cgroup *old = NULL;
unsigned long flags;
/*
* The only protection from cpu hotplug (memcg_hotplug_cpu_dead) vs.
* drain_stock races is that we always operate on local CPU stock
* here with IRQ disabled
*/
local_lock_irqsave(&memcg_stock.stock_lock, flags);
stock = this_cpu_ptr(&memcg_stock);
old = drain_obj_stock(stock);
drain_stock(stock);
clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
if (old)
obj_cgroup_put(old);
}
/*
* Cache charges(val) to local per_cpu area.
* This will be consumed by consume_stock() function, later.
*/
static void __refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
{
struct memcg_stock_pcp *stock;
stock = this_cpu_ptr(&memcg_stock);
if (READ_ONCE(stock->cached) != memcg) { /* reset if necessary */
drain_stock(stock);
css_get(&memcg->css);
WRITE_ONCE(stock->cached, memcg);
}
stock->nr_pages += nr_pages;
if (stock->nr_pages > MEMCG_CHARGE_BATCH)
drain_stock(stock);
}
static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
{
unsigned long flags;
local_lock_irqsave(&memcg_stock.stock_lock, flags);
__refill_stock(memcg, nr_pages);
local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
}
/*
* Drains all per-CPU charge caches for given root_memcg resp. subtree
* of the hierarchy under it.
*/
static void drain_all_stock(struct mem_cgroup *root_memcg)
{
int cpu, curcpu;
/* If someone's already draining, avoid adding running more workers. */
if (!mutex_trylock(&percpu_charge_mutex))
return;
/*
* Notify other cpus that system-wide "drain" is running
* We do not care about races with the cpu hotplug because cpu down
* as well as workers from this path always operate on the local
* per-cpu data. CPU up doesn't touch memcg_stock at all.
*/
migrate_disable();
curcpu = smp_processor_id();
for_each_online_cpu(cpu) {
struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
struct mem_cgroup *memcg;
bool flush = false;
rcu_read_lock();
memcg = READ_ONCE(stock->cached);
if (memcg && stock->nr_pages &&
mem_cgroup_is_descendant(memcg, root_memcg))
flush = true;
else if (obj_stock_flush_required(stock, root_memcg))
flush = true;
rcu_read_unlock();
if (flush &&
!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
if (cpu == curcpu)
drain_local_stock(&stock->work);
else if (!cpu_is_isolated(cpu))
schedule_work_on(cpu, &stock->work);
}
}
migrate_enable();
mutex_unlock(&percpu_charge_mutex);
}
static int memcg_hotplug_cpu_dead(unsigned int cpu)
{
struct memcg_stock_pcp *stock;
stock = &per_cpu(memcg_stock, cpu);
drain_stock(stock);
return 0;
}
static unsigned long reclaim_high(struct mem_cgroup *memcg,
unsigned int nr_pages,
gfp_t gfp_mask)
{
unsigned long nr_reclaimed = 0;
do {
unsigned long pflags;
if (page_counter_read(&memcg->memory) <=
READ_ONCE(memcg->memory.high))
continue;
memcg_memory_event(memcg, MEMCG_HIGH);
psi_memstall_enter(&pflags);
nr_reclaimed += try_to_free_mem_cgroup_pages(memcg, nr_pages,
gfp_mask,
MEMCG_RECLAIM_MAY_SWAP);
psi_memstall_leave(&pflags);
} while ((memcg = parent_mem_cgroup(memcg)) &&
!mem_cgroup_is_root(memcg));
return nr_reclaimed;
}
static void high_work_func(struct work_struct *work)
{
struct mem_cgroup *memcg;
memcg = container_of(work, struct mem_cgroup, high_work);
reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL);
}
/*
* Clamp the maximum sleep time per allocation batch to 2 seconds. This is
* enough to still cause a significant slowdown in most cases, while still
* allowing diagnostics and tracing to proceed without becoming stuck.
*/
#define MEMCG_MAX_HIGH_DELAY_JIFFIES (2UL*HZ)
/*
* When calculating the delay, we use these either side of the exponentiation to
* maintain precision and scale to a reasonable number of jiffies (see the table
* below.
*
* - MEMCG_DELAY_PRECISION_SHIFT: Extra precision bits while translating the
* overage ratio to a delay.
* - MEMCG_DELAY_SCALING_SHIFT: The number of bits to scale down the
* proposed penalty in order to reduce to a reasonable number of jiffies, and
* to produce a reasonable delay curve.
*
* MEMCG_DELAY_SCALING_SHIFT just happens to be a number that produces a
* reasonable delay curve compared to precision-adjusted overage, not
* penalising heavily at first, but still making sure that growth beyond the
* limit penalises misbehaviour cgroups by slowing them down exponentially. For
* example, with a high of 100 megabytes:
*
* +-------+------------------------+
* | usage | time to allocate in ms |
* +-------+------------------------+
* | 100M | 0 |
* | 101M | 6 |
* | 102M | 25 |
* | 103M | 57 |
* | 104M | 102 |
* | 105M | 159 |
* | 106M | 230 |
* | 107M | 313 |
* | 108M | 409 |
* | 109M | 518 |
* | 110M | 639 |
* | 111M | 774 |
* | 112M | 921 |
* | 113M | 1081 |
* | 114M | 1254 |
* | 115M | 1439 |
* | 116M | 1638 |
* | 117M | 1849 |
* | 118M | 2000 |
* | 119M | 2000 |
* | 120M | 2000 |
* +-------+------------------------+
*/
#define MEMCG_DELAY_PRECISION_SHIFT 20
#define MEMCG_DELAY_SCALING_SHIFT 14
static u64 calculate_overage(unsigned long usage, unsigned long high)
{
u64 overage;
if (usage <= high)
return 0;
/*
* Prevent division by 0 in overage calculation by acting as if
* it was a threshold of 1 page
*/
high = max(high, 1UL);
overage = usage - high;
overage <<= MEMCG_DELAY_PRECISION_SHIFT;
return div64_u64(overage, high);
}
static u64 mem_find_max_overage(struct mem_cgroup *memcg)
{
u64 overage, max_overage = 0;
do {
overage = calculate_overage(page_counter_read(&memcg->memory),
READ_ONCE(memcg->memory.high));
max_overage = max(overage, max_overage);
} while ((memcg = parent_mem_cgroup(memcg)) &&
!mem_cgroup_is_root(memcg));
return max_overage;
}
static u64 swap_find_max_overage(struct mem_cgroup *memcg)
{
u64 overage, max_overage = 0;
do {
overage = calculate_overage(page_counter_read(&memcg->swap),
READ_ONCE(memcg->swap.high));
if (overage)
memcg_memory_event(memcg, MEMCG_SWAP_HIGH);
max_overage = max(overage, max_overage);
} while ((memcg = parent_mem_cgroup(memcg)) &&
!mem_cgroup_is_root(memcg));
return max_overage;
}
/*
* Get the number of jiffies that we should penalise a mischievous cgroup which
* is exceeding its memory.high by checking both it and its ancestors.
*/
static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
unsigned int nr_pages,
u64 max_overage)
{
unsigned long penalty_jiffies;
if (!max_overage)
return 0;
/*
* We use overage compared to memory.high to calculate the number of
* jiffies to sleep (penalty_jiffies). Ideally this value should be
* fairly lenient on small overages, and increasingly harsh when the
* memcg in question makes it clear that it has no intention of stopping
* its crazy behaviour, so we exponentially increase the delay based on
* overage amount.
*/
penalty_jiffies = max_overage * max_overage * HZ;
penalty_jiffies >>= MEMCG_DELAY_PRECISION_SHIFT;
penalty_jiffies >>= MEMCG_DELAY_SCALING_SHIFT;
/*
* Factor in the task's own contribution to the overage, such that four
* N-sized allocations are throttled approximately the same as one
* 4N-sized allocation.
*
* MEMCG_CHARGE_BATCH pages is nominal, so work out how much smaller or
* larger the current charge patch is than that.
*/
return penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH;
}
/*
* Reclaims memory over the high limit. Called directly from
* try_charge() (context permitting), as well as from the userland
* return path where reclaim is always able to block.
*/
void mem_cgroup_handle_over_high(gfp_t gfp_mask)
{
unsigned long penalty_jiffies;
unsigned long pflags;
unsigned long nr_reclaimed;
unsigned int nr_pages = current->memcg_nr_pages_over_high;
int nr_retries = MAX_RECLAIM_RETRIES;
struct mem_cgroup *memcg;
bool in_retry = false;
if (likely(!nr_pages))
return;
memcg = get_mem_cgroup_from_mm(current->mm);
current->memcg_nr_pages_over_high = 0;
retry_reclaim:
/*
* Bail if the task is already exiting. Unlike memory.max,
* memory.high enforcement isn't as strict, and there is no
* OOM killer involved, which means the excess could already
* be much bigger (and still growing) than it could for
* memory.max; the dying task could get stuck in fruitless
* reclaim for a long time, which isn't desirable.
*/
if (task_is_dying())
goto out;
/*
* The allocating task should reclaim at least the batch size, but for
* subsequent retries we only want to do what's necessary to prevent oom
* or breaching resource isolation.
*
* This is distinct from memory.max or page allocator behaviour because
* memory.high is currently batched, whereas memory.max and the page
* allocator run every time an allocation is made.
*/
nr_reclaimed = reclaim_high(memcg,
in_retry ? SWAP_CLUSTER_MAX : nr_pages,
gfp_mask);
/*
* memory.high is breached and reclaim is unable to keep up. Throttle
* allocators proactively to slow down excessive growth.
*/
penalty_jiffies = calculate_high_delay(memcg, nr_pages,
mem_find_max_overage(memcg));
penalty_jiffies += calculate_high_delay(memcg, nr_pages,
swap_find_max_overage(memcg));
/*
* Clamp the max delay per usermode return so as to still keep the
* application moving forwards and also permit diagnostics, albeit
* extremely slowly.
*/
penalty_jiffies = min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES);
/*
* Don't sleep if the amount of jiffies this memcg owes us is so low
* that it's not even worth doing, in an attempt to be nice to those who
* go only a small amount over their memory.high value and maybe haven't
* been aggressively reclaimed enough yet.
*/
if (penalty_jiffies <= HZ / 100)
goto out;
/*
* If reclaim is making forward progress but we're still over
* memory.high, we want to encourage that rather than doing allocator
* throttling.
*/
if (nr_reclaimed || nr_retries--) {
in_retry = true;
goto retry_reclaim;
}
/*
* Reclaim didn't manage to push usage below the limit, slow
* this allocating task down.
*
* If we exit early, we're guaranteed to die (since
* schedule_timeout_killable sets TASK_KILLABLE). This means we don't
* need to account for any ill-begotten jiffies to pay them off later.
*/
psi_memstall_enter(&pflags);
schedule_timeout_killable(penalty_jiffies);
psi_memstall_leave(&pflags);
out:
css_put(&memcg->css);
}
static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
unsigned int nr_pages)
{
unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);
int nr_retries = MAX_RECLAIM_RETRIES;
struct mem_cgroup *mem_over_limit;
struct page_counter *counter;
unsigned long nr_reclaimed;
bool passed_oom = false;
unsigned int reclaim_options = MEMCG_RECLAIM_MAY_SWAP;
bool drained = false;
bool raised_max_event = false;
unsigned long pflags;
retry:
if (consume_stock(memcg, nr_pages))
return 0;
if (!do_memsw_account() ||
page_counter_try_charge(&memcg->memsw, batch, &counter)) {
if (page_counter_try_charge(&memcg->memory, batch, &counter))
goto done_restock;
if (do_memsw_account())
page_counter_uncharge(&memcg->memsw, batch);
mem_over_limit = mem_cgroup_from_counter(counter, memory);
} else {
mem_over_limit = mem_cgroup_from_counter(counter, memsw);
reclaim_options &= ~MEMCG_RECLAIM_MAY_SWAP;
}
if (batch > nr_pages) {
batch = nr_pages;
goto retry;
}
/*
* Prevent unbounded recursion when reclaim operations need to
* allocate memory. This might exceed the limits temporarily,
* but we prefer facilitating memory reclaim and getting back
* under the limit over triggering OOM kills in these cases.
*/
if (unlikely(current->flags & PF_MEMALLOC))
goto force;
if (unlikely(task_in_memcg_oom(current)))
goto nomem;
if (!gfpflags_allow_blocking(gfp_mask))
goto nomem;
memcg_memory_event(mem_over_limit, MEMCG_MAX);
raised_max_event = true;
psi_memstall_enter(&pflags);
nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages,
gfp_mask, reclaim_options);
psi_memstall_leave(&pflags);
if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
goto retry;
if (!drained) {
drain_all_stock(mem_over_limit);
drained = true;
goto retry;
}
if (gfp_mask & __GFP_NORETRY)
goto nomem;
/*
* Even though the limit is exceeded at this point, reclaim
* may have been able to free some pages. Retry the charge
* before killing the task.
*
* Only for regular pages, though: huge pages are rather
* unlikely to succeed so close to the limit, and we fall back
* to regular pages anyway in case of failure.
*/
if (nr_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER))
goto retry;
/*
* At task move, charge accounts can be doubly counted. So, it's
* better to wait until the end of task_move if something is going on.
*/
if (mem_cgroup_wait_acct_move(mem_over_limit))
goto retry;
if (nr_retries--)
goto retry;
if (gfp_mask & __GFP_RETRY_MAYFAIL)
goto nomem;
/* Avoid endless loop for tasks bypassed by the oom killer */
if (passed_oom && task_is_dying())
goto nomem;
/*
* keep retrying as long as the memcg oom killer is able to make
* a forward progress or bypass the charge if the oom killer
* couldn't make any progress.
*/
if (mem_cgroup_oom(mem_over_limit, gfp_mask,
get_order(nr_pages * PAGE_SIZE))) {
passed_oom = true;
nr_retries = MAX_RECLAIM_RETRIES;
goto retry;
}
nomem:
/*
* Memcg doesn't have a dedicated reserve for atomic
* allocations. But like the global atomic pool, we need to
* put the burden of reclaim on regular allocation requests
* and let these go through as privileged allocations.
*/
if (!(gfp_mask & (__GFP_NOFAIL | __GFP_HIGH)))
return -ENOMEM;
force:
/*
* If the allocation has to be enforced, don't forget to raise
* a MEMCG_MAX event.
*/
if (!raised_max_event)
memcg_memory_event(mem_over_limit, MEMCG_MAX);
/*
* The allocation either can't fail or will lead to more memory
* being freed very soon. Allow memory usage go over the limit
* temporarily by force charging it.
*/
page_counter_charge(&memcg->memory, nr_pages);
if (do_memsw_account())
page_counter_charge(&memcg->memsw, nr_pages);
return 0;
done_restock:
if (batch > nr_pages)
refill_stock(memcg, batch - nr_pages);
/*
* If the hierarchy is above the normal consumption range, schedule
* reclaim on returning to userland. We can perform reclaim here
* if __GFP_RECLAIM but let's always punt for simplicity and so that
* GFP_KERNEL can consistently be used during reclaim. @memcg is
* not recorded as it most likely matches current's and won't
* change in the meantime. As high limit is checked again before
* reclaim, the cost of mismatch is negligible.
*/
do {
bool mem_high, swap_high;
mem_high = page_counter_read(&memcg->memory) >
READ_ONCE(memcg->memory.high);
swap_high = page_counter_read(&memcg->swap) >
READ_ONCE(memcg->swap.high);
/* Don't bother a random interrupted task */
if (!in_task()) {
if (mem_high) {
schedule_work(&memcg->high_work);
break;
}
continue;
}
if (mem_high || swap_high) {
/*
* The allocating tasks in this cgroup will need to do
* reclaim or be throttled to prevent further growth
* of the memory or swap footprints.
*
* Target some best-effort fairness between the tasks,
* and distribute reclaim work and delay penalties
* based on how much each task is actually allocating.
*/
current->memcg_nr_pages_over_high += batch;
set_notify_resume(current);
break;
}
} while ((memcg = parent_mem_cgroup(memcg)));
/*
* Reclaim is set up above to be called from the userland
* return path. But also attempt synchronous reclaim to avoid
* excessive overrun while the task is still inside the
* kernel. If this is successful, the return path will see it
* when it rechecks the overage and simply bail out.
*/
if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH &&
!(current->flags & PF_MEMALLOC) &&
gfpflags_allow_blocking(gfp_mask))
mem_cgroup_handle_over_high(gfp_mask);
return 0;
}
static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
unsigned int nr_pages)
{
if (mem_cgroup_is_root(memcg))
return 0;
return try_charge_memcg(memcg, gfp_mask, nr_pages);
}
/**
* mem_cgroup_cancel_charge() - cancel an uncommitted try_charge() call.
* @memcg: memcg previously charged.
* @nr_pages: number of pages previously charged.
*/
void mem_cgroup_cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
{
if (mem_cgroup_is_root(memcg))
return;
page_counter_uncharge(&memcg->memory, nr_pages);
if (do_memsw_account())
page_counter_uncharge(&memcg->memsw, nr_pages);
}
static void commit_charge(struct folio *folio, struct mem_cgroup *memcg)
{
VM_BUG_ON_FOLIO(folio_memcg(folio), folio);
/*
* Any of the following ensures page's memcg stability:
*
* - the page lock
* - LRU isolation
* - folio_memcg_lock()
* - exclusive reference
* - mem_cgroup_trylock_pages()
*/
folio->memcg_data = (unsigned long)memcg;
}
/**
* mem_cgroup_commit_charge - commit a previously successful try_charge().
* @folio: folio to commit the charge to.
* @memcg: memcg previously charged.
*/
void mem_cgroup_commit_charge(struct folio *folio, struct mem_cgroup *memcg)
{
css_get(&memcg->css);
commit_charge(folio, memcg);
local_irq_disable();
mem_cgroup_charge_statistics(memcg, folio_nr_pages(folio));
memcg_check_events(memcg, folio_nid(folio));
local_irq_enable();
}
#ifdef CONFIG_MEMCG_KMEM
/*
* The allocated objcg pointers array is not accounted directly.
* Moreover, it should not come from DMA buffer and is not readily
* reclaimable. So those GFP bits should be masked off.
*/
#define OBJCGS_CLEAR_MASK (__GFP_DMA | __GFP_RECLAIMABLE | \
__GFP_ACCOUNT | __GFP_NOFAIL)
/*
* mod_objcg_mlstate() may be called with irq enabled, so
* mod_memcg_lruvec_state() should be used.
*/
static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
struct pglist_data *pgdat,
enum node_stat_item idx, int nr)
{
struct mem_cgroup *memcg;
struct lruvec *lruvec;
rcu_read_lock();
memcg = obj_cgroup_memcg(objcg);
lruvec = mem_cgroup_lruvec(memcg, pgdat);
mod_memcg_lruvec_state(lruvec, idx, nr);
rcu_read_unlock();
}
int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s,
gfp_t gfp, bool new_slab)
{
unsigned int objects = objs_per_slab(s, slab);
unsigned long memcg_data;
void *vec;
gfp &= ~OBJCGS_CLEAR_MASK;
vec = kcalloc_node(objects, sizeof(struct obj_cgroup *), gfp,
slab_nid(slab));
if (!vec)
return -ENOMEM;
memcg_data = (unsigned long) vec | MEMCG_DATA_OBJCGS;
if (new_slab) {
/*
* If the slab is brand new and nobody can yet access its
* memcg_data, no synchronization is required and memcg_data can
* be simply assigned.
*/
slab->memcg_data = memcg_data;
} else if (cmpxchg(&slab->memcg_data, 0, memcg_data)) {
/*
* If the slab is already in use, somebody can allocate and
* assign obj_cgroups in parallel. In this case the existing
* objcg vector should be reused.
*/
kfree(vec);
return 0;
}
kmemleak_not_leak(vec);
return 0;
}
static __always_inline
struct mem_cgroup *mem_cgroup_from_obj_folio(struct folio *folio, void *p)
{
/*
* Slab objects are accounted individually, not per-page.
* Memcg membership data for each individual object is saved in
* slab->memcg_data.
*/
if (folio_test_slab(folio)) {
struct obj_cgroup **objcgs;
struct slab *slab;
unsigned int off;
slab = folio_slab(folio);
objcgs = slab_objcgs(slab);
if (!objcgs)
return NULL;
off = obj_to_index(slab->slab_cache, slab, p);
if (objcgs[off])
return obj_cgroup_memcg(objcgs[off]);
return NULL;
}
/*
* folio_memcg_check() is used here, because in theory we can encounter
* a folio where the slab flag has been cleared already, but
* slab->memcg_data has not been freed yet
* folio_memcg_check() will guarantee that a proper memory
* cgroup pointer or NULL will be returned.
*/
return folio_memcg_check(folio);
}
/*
* Returns a pointer to the memory cgroup to which the kernel object is charged.
*
* A passed kernel object can be a slab object, vmalloc object or a generic
* kernel page, so different mechanisms for getting the memory cgroup pointer
* should be used.
*
* In certain cases (e.g. kernel stacks or large kmallocs with SLUB) the caller
* can not know for sure how the kernel object is implemented.
* mem_cgroup_from_obj() can be safely used in such cases.
*
* The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
* cgroup_mutex, etc.
*/
struct mem_cgroup *mem_cgroup_from_obj(void *p)
{
struct folio *folio;
if (mem_cgroup_disabled())
return NULL;
if (unlikely(is_vmalloc_addr(p)))
folio = page_folio(vmalloc_to_page(p));
else
folio = virt_to_folio(p);
return mem_cgroup_from_obj_folio(folio, p);
}
/*
* Returns a pointer to the memory cgroup to which the kernel object is charged.
* Similar to mem_cgroup_from_obj(), but faster and not suitable for objects,
* allocated using vmalloc().
*
* A passed kernel object must be a slab object or a generic kernel page.
*
* The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
* cgroup_mutex, etc.
*/
struct mem_cgroup *mem_cgroup_from_slab_obj(void *p)
{
if (mem_cgroup_disabled())
return NULL;
return mem_cgroup_from_obj_folio(virt_to_folio(p), p);
}
static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg)
{
struct obj_cgroup *objcg = NULL;
for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) {
objcg = rcu_dereference(memcg->objcg);
if (likely(objcg && obj_cgroup_tryget(objcg)))
break;
objcg = NULL;
}
return objcg;
}
static struct obj_cgroup *current_objcg_update(void)
{
struct mem_cgroup *memcg;
struct obj_cgroup *old, *objcg = NULL;
do {
/* Atomically drop the update bit. */
old = xchg(&current->objcg, NULL);
if (old) {
old = (struct obj_cgroup *)
((unsigned long)old & ~CURRENT_OBJCG_UPDATE_FLAG);
if (old)
obj_cgroup_put(old);
old = NULL;
}
/* If new objcg is NULL, no reason for the second atomic update. */
if (!current->mm || (current->flags & PF_KTHREAD))
return NULL;
/*
* Release the objcg pointer from the previous iteration,
* if try_cmpxcg() below fails.
*/
if (unlikely(objcg)) {
obj_cgroup_put(objcg);
objcg = NULL;
}
/*
* Obtain the new objcg pointer. The current task can be
* asynchronously moved to another memcg and the previous
* memcg can be offlined. So let's get the memcg pointer
* and try get a reference to objcg under a rcu read lock.
*/
rcu_read_lock();
memcg = mem_cgroup_from_task(current);
objcg = __get_obj_cgroup_from_memcg(memcg);
rcu_read_unlock();
/*
* Try set up a new objcg pointer atomically. If it
* fails, it means the update flag was set concurrently, so
* the whole procedure should be repeated.
*/
} while (!try_cmpxchg(&current->objcg, &old, objcg));
return objcg;
}
__always_inline struct obj_cgroup *current_obj_cgroup(void)
{
struct mem_cgroup *memcg;
struct obj_cgroup *objcg;
if (in_task()) {
memcg = current->active_memcg;
if (unlikely(memcg))
goto from_memcg;
objcg = READ_ONCE(current->objcg);
if (unlikely((unsigned long)objcg & CURRENT_OBJCG_UPDATE_FLAG))
objcg = current_objcg_update();
/*
* Objcg reference is kept by the task, so it's safe
* to use the objcg by the current task.
*/
return objcg;
}
memcg = this_cpu_read(int_active_memcg);
if (unlikely(memcg))
goto from_memcg;
return NULL;
from_memcg:
objcg = NULL;
for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) {
/*
* Memcg pointer is protected by scope (see set_active_memcg())
* and is pinning the corresponding objcg, so objcg can't go
* away and can be used within the scope without any additional
* protection.
*/
objcg = rcu_dereference_check(memcg->objcg, 1);
if (likely(objcg))
break;
}
return objcg;
}
struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio)
{
struct obj_cgroup *objcg;
if (!memcg_kmem_online())
return NULL;
if (folio_memcg_kmem(folio)) {
objcg = __folio_objcg(folio);
obj_cgroup_get(objcg);
} else {
struct mem_cgroup *memcg;
rcu_read_lock();
memcg = __folio_memcg(folio);
if (memcg)
objcg = __get_obj_cgroup_from_memcg(memcg);
else
objcg = NULL;
rcu_read_unlock();
}
return objcg;
}
static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
{
mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
if (nr_pages > 0)
page_counter_charge(&memcg->kmem, nr_pages);
else
page_counter_uncharge(&memcg->kmem, -nr_pages);
}
}
/*
* obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg
* @objcg: object cgroup to uncharge
* @nr_pages: number of pages to uncharge
*/
static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
unsigned int nr_pages)
{
struct mem_cgroup *memcg;
memcg = get_mem_cgroup_from_objcg(objcg);
memcg_account_kmem(memcg, -nr_pages);
refill_stock(memcg, nr_pages);
css_put(&memcg->css);
}
/*
* obj_cgroup_charge_pages: charge a number of kernel pages to a objcg
* @objcg: object cgroup to charge
* @gfp: reclaim mode
* @nr_pages: number of pages to charge
*
* Returns 0 on success, an error code on failure.
*/
static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
unsigned int nr_pages)
{
struct mem_cgroup *memcg;
int ret;
memcg = get_mem_cgroup_from_objcg(objcg);
ret = try_charge_memcg(memcg, gfp, nr_pages);
if (ret)
goto out;
memcg_account_kmem(memcg, nr_pages);
out:
css_put(&memcg->css);
return ret;
}
/**
* __memcg_kmem_charge_page: charge a kmem page to the current memory cgroup
* @page: page to charge
* @gfp: reclaim mode
* @order: allocation order
*
* Returns 0 on success, an error code on failure.
*/
int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order)
{
struct obj_cgroup *objcg;
int ret = 0;
objcg = current_obj_cgroup();
if (objcg) {
ret = obj_cgroup_charge_pages(objcg, gfp, 1 << order);
if (!ret) {
obj_cgroup_get(objcg);
page->memcg_data = (unsigned long)objcg |
MEMCG_DATA_KMEM;
return 0;
}
}
return ret;
}
/**
* __memcg_kmem_uncharge_page: uncharge a kmem page
* @page: page to uncharge
* @order: allocation order
*/
void __memcg_kmem_uncharge_page(struct page *page, int order)
{
struct folio *folio = page_folio(page);
struct obj_cgroup *objcg;
unsigned int nr_pages = 1 << order;
if (!folio_memcg_kmem(folio))
return;
objcg = __folio_objcg(folio);
obj_cgroup_uncharge_pages(objcg, nr_pages);
folio->memcg_data = 0;
obj_cgroup_put(objcg);
}
void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
enum node_stat_item idx, int nr)
{
struct memcg_stock_pcp *stock;
struct obj_cgroup *old = NULL;
unsigned long flags;
int *bytes;
local_lock_irqsave(&memcg_stock.stock_lock, flags);
stock = this_cpu_ptr(&memcg_stock);
/*
* Save vmstat data in stock and skip vmstat array update unless
* accumulating over a page of vmstat data or when pgdat or idx
* changes.
*/
if (READ_ONCE(stock->cached_objcg) != objcg) {
old = drain_obj_stock(stock);
obj_cgroup_get(objcg);
stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
WRITE_ONCE(stock->cached_objcg, objcg);
stock->cached_pgdat = pgdat;
} else if (stock->cached_pgdat != pgdat) {
/* Flush the existing cached vmstat data */
struct pglist_data *oldpg = stock->cached_pgdat;
if (stock->nr_slab_reclaimable_b) {
mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B,
stock->nr_slab_reclaimable_b);
stock->nr_slab_reclaimable_b = 0;
}
if (stock->nr_slab_unreclaimable_b) {
mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B,
stock->nr_slab_unreclaimable_b);
stock->nr_slab_unreclaimable_b = 0;
}
stock->cached_pgdat = pgdat;
}
bytes = (idx == NR_SLAB_RECLAIMABLE_B) ? &stock->nr_slab_reclaimable_b
: &stock->nr_slab_unreclaimable_b;
/*
* Even for large object >= PAGE_SIZE, the vmstat data will still be
* cached locally at least once before pushing it out.
*/
if (!*bytes) {
*bytes = nr;
nr = 0;
} else {
*bytes += nr;
if (abs(*bytes) > PAGE_SIZE) {
nr = *bytes;
*bytes = 0;
} else {
nr = 0;
}
}
if (nr)
mod_objcg_mlstate(objcg, pgdat, idx, nr);
local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
if (old)
obj_cgroup_put(old);
}
static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
{
struct memcg_stock_pcp *stock;
unsigned long flags;
bool ret = false;
local_lock_irqsave(&memcg_stock.stock_lock, flags);
stock = this_cpu_ptr(&memcg_stock);
if (objcg == READ_ONCE(stock->cached_objcg) && stock->nr_bytes >= nr_bytes) {
stock->nr_bytes -= nr_bytes;
ret = true;
}
local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
return ret;
}
static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock)
{
struct obj_cgroup *old = READ_ONCE(stock->cached_objcg);
if (!old)
return NULL;
if (stock->nr_bytes) {
unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
if (nr_pages) {
struct mem_cgroup *memcg;
memcg = get_mem_cgroup_from_objcg(old);
memcg_account_kmem(memcg, -nr_pages);
__refill_stock(memcg, nr_pages);
css_put(&memcg->css);
}
/*
* The leftover is flushed to the centralized per-memcg value.
* On the next attempt to refill obj stock it will be moved
* to a per-cpu stock (probably, on an other CPU), see
* refill_obj_stock().
*
* How often it's flushed is a trade-off between the memory
* limit enforcement accuracy and potential CPU contention,
* so it might be changed in the future.
*/
atomic_add(nr_bytes, &old->nr_charged_bytes);
stock->nr_bytes = 0;
}
/*
* Flush the vmstat data in current stock
*/
if (stock->nr_slab_reclaimable_b || stock->nr_slab_unreclaimable_b) {
if (stock->nr_slab_reclaimable_b) {
mod_objcg_mlstate(old, stock->cached_pgdat,
NR_SLAB_RECLAIMABLE_B,
stock->nr_slab_reclaimable_b);
stock->nr_slab_reclaimable_b = 0;
}
if (stock->nr_slab_unreclaimable_b) {
mod_objcg_mlstate(old, stock->cached_pgdat,
NR_SLAB_UNRECLAIMABLE_B,
stock->nr_slab_unreclaimable_b);
stock->nr_slab_unreclaimable_b = 0;
}
stock->cached_pgdat = NULL;
}
WRITE_ONCE(stock->cached_objcg, NULL);
/*
* The `old' objects needs to be released by the caller via
* obj_cgroup_put() outside of memcg_stock_pcp::stock_lock.
*/
return old;
}
static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
struct mem_cgroup *root_memcg)
{
struct obj_cgroup *objcg = READ_ONCE(stock->cached_objcg);
struct mem_cgroup *memcg;
if (objcg) {
memcg = obj_cgroup_memcg(objcg);
if (memcg && mem_cgroup_is_descendant(memcg, root_memcg))
return true;
}
return false;
}
static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
bool allow_uncharge)
{
struct memcg_stock_pcp *stock;
struct obj_cgroup *old = NULL;
unsigned long flags;
unsigned int nr_pages = 0;
local_lock_irqsave(&memcg_stock.stock_lock, flags);
stock = this_cpu_ptr(&memcg_stock);
if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */
old = drain_obj_stock(stock);
obj_cgroup_get(objcg);
WRITE_ONCE(stock->cached_objcg, objcg);
stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
allow_uncharge = true; /* Allow uncharge when objcg changes */
}
stock->nr_bytes += nr_bytes;
if (allow_uncharge && (stock->nr_bytes > PAGE_SIZE)) {
nr_pages = stock->nr_bytes >> PAGE_SHIFT;
stock->nr_bytes &= (PAGE_SIZE - 1);
}
local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
if (old)
obj_cgroup_put(old);
if (nr_pages)
obj_cgroup_uncharge_pages(objcg, nr_pages);
}
int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
{
unsigned int nr_pages, nr_bytes;
int ret;
if (consume_obj_stock(objcg, size))
return 0;
/*
* In theory, objcg->nr_charged_bytes can have enough
* pre-charged bytes to satisfy the allocation. However,
* flushing objcg->nr_charged_bytes requires two atomic
* operations, and objcg->nr_charged_bytes can't be big.
* The shared objcg->nr_charged_bytes can also become a
* performance bottleneck if all tasks of the same memcg are
* trying to update it. So it's better to ignore it and try
* grab some new pages. The stock's nr_bytes will be flushed to
* objcg->nr_charged_bytes later on when objcg changes.
*
* The stock's nr_bytes may contain enough pre-charged bytes
* to allow one less page from being charged, but we can't rely
* on the pre-charged bytes not being changed outside of
* consume_obj_stock() or refill_obj_stock(). So ignore those
* pre-charged bytes as well when charging pages. To avoid a
* page uncharge right after a page charge, we set the
* allow_uncharge flag to false when calling refill_obj_stock()
* to temporarily allow the pre-charged bytes to exceed the page
* size limit. The maximum reachable value of the pre-charged
* bytes is (sizeof(object) + PAGE_SIZE - 2) if there is no data
* race.
*/
nr_pages = size >> PAGE_SHIFT;
nr_bytes = size & (PAGE_SIZE - 1);
if (nr_bytes)
nr_pages += 1;
ret = obj_cgroup_charge_pages(objcg, gfp, nr_pages);
if (!ret && nr_bytes)
refill_obj_stock(objcg, PAGE_SIZE - nr_bytes, false);
return ret;
}
void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
{
refill_obj_stock(objcg, size, true);
}
#endif /* CONFIG_MEMCG_KMEM */
/*
* Because page_memcg(head) is not set on tails, set it now.
*/
void split_page_memcg(struct page *head, int old_order, int new_order)
{
struct folio *folio = page_folio(head);
struct mem_cgroup *memcg = folio_memcg(folio);
int i;
unsigned int old_nr = 1 << old_order;
unsigned int new_nr = 1 << new_order;
if (mem_cgroup_disabled() || !memcg)
return;
for (i = new_nr; i < old_nr; i += new_nr)
folio_page(folio, i)->memcg_data = folio->memcg_data;
if (folio_memcg_kmem(folio))
obj_cgroup_get_many(__folio_objcg(folio), old_nr / new_nr - 1);
else
css_get_many(&memcg->css, old_nr / new_nr - 1);
}
#ifdef CONFIG_SWAP
/**
* mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
* @entry: swap entry to be moved
* @from: mem_cgroup which the entry is moved from
* @to: mem_cgroup which the entry is moved to
*
* It succeeds only when the swap_cgroup's record for this entry is the same
* as the mem_cgroup's id of @from.
*
* Returns 0 on success, -EINVAL on failure.
*
* The caller must have charged to @to, IOW, called page_counter_charge() about
* both res and memsw, and called css_get().
*/
static int mem_cgroup_move_swap_account(swp_entry_t entry,
struct mem_cgroup *from, struct mem_cgroup *to)
{
unsigned short old_id, new_id;
old_id = mem_cgroup_id(from);
new_id = mem_cgroup_id(to);
if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
mod_memcg_state(from, MEMCG_SWAP, -1);
mod_memcg_state(to, MEMCG_SWAP, 1);
return 0;
}
return -EINVAL;
}
#else
static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
struct mem_cgroup *from, struct mem_cgroup *to)
{
return -EINVAL;
}
#endif
static DEFINE_MUTEX(memcg_max_mutex);
static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
unsigned long max, bool memsw)
{
bool enlarge = false;
bool drained = false;
int ret;
bool limits_invariant;
struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory;
do {
if (signal_pending(current)) {
ret = -EINTR;
break;
}
mutex_lock(&memcg_max_mutex);
/*
* Make sure that the new limit (memsw or memory limit) doesn't
* break our basic invariant rule memory.max <= memsw.max.
*/
limits_invariant = memsw ? max >= READ_ONCE(memcg->memory.max) :
max <= memcg->memsw.max;
if (!limits_invariant) {
mutex_unlock(&memcg_max_mutex);
ret = -EINVAL;
break;
}
if (max > counter->max)
enlarge = true;
ret = page_counter_set_max(counter, max);
mutex_unlock(&memcg_max_mutex);
if (!ret)
break;
if (!drained) {
drain_all_stock(memcg);
drained = true;
continue;
}
if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL,
memsw ? 0 : MEMCG_RECLAIM_MAY_SWAP)) {
ret = -EBUSY;
break;
}
} while (true);
if (!ret && enlarge)
memcg_oom_recover(memcg);
return ret;
}
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
gfp_t gfp_mask,
unsigned long *total_scanned)
{
unsigned long nr_reclaimed = 0;
struct mem_cgroup_per_node *mz, *next_mz = NULL;
unsigned long reclaimed;
int loop = 0;
struct mem_cgroup_tree_per_node *mctz;
unsigned long excess;
if (lru_gen_enabled())
return 0;
if (order > 0)
return 0;
mctz = soft_limit_tree.rb_tree_per_node[pgdat->node_id];
/*
* Do not even bother to check the largest node if the root
* is empty. Do it lockless to prevent lock bouncing. Races
* are acceptable as soft limit is best effort anyway.
*/
if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root))
return 0;
/*
* This loop can run a while, specially if mem_cgroup's continuously
* keep exceeding their soft limit and putting the system under
* pressure
*/
do {
if (next_mz)
mz = next_mz;
else
mz = mem_cgroup_largest_soft_limit_node(mctz);
if (!mz)
break;
reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
gfp_mask, total_scanned);
nr_reclaimed += reclaimed;
spin_lock_irq(&mctz->lock);
/*
* If we failed to reclaim anything from this memory cgroup
* it is time to move on to the next cgroup
*/
next_mz = NULL;
if (!reclaimed)
next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
excess = soft_limit_excess(mz->memcg);
/*
* One school of thought says that we should not add
* back the node to the tree if reclaim returns 0.
* But our reclaim could return 0, simply because due
* to priority we are exposing a smaller subset of
* memory to reclaim from. Consider this as a longer
* term TODO.
*/
/* If excess == 0, no tree ops */
__mem_cgroup_insert_exceeded(mz, mctz, excess);
spin_unlock_irq(&mctz->lock);
css_put(&mz->memcg->css);
loop++;
/*
* Could not reclaim anything and there are no more
* mem cgroups to try or we seem to be looping without
* reclaiming anything.
*/
if (!nr_reclaimed &&
(next_mz == NULL ||
loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
break;
} while (!nr_reclaimed);
if (next_mz)
css_put(&next_mz->memcg->css);
return nr_reclaimed;
}
/*
* Reclaims as many pages from the given memcg as possible.
*
* Caller is responsible for holding css reference for memcg.
*/
static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
{
int nr_retries = MAX_RECLAIM_RETRIES;
/* we call try-to-free pages for make this cgroup empty */
lru_add_drain_all();
drain_all_stock(memcg);
/* try to free all pages in this cgroup */
while (nr_retries && page_counter_read(&memcg->memory)) {
if (signal_pending(current))
return -EINTR;
if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL,
MEMCG_RECLAIM_MAY_SWAP))
nr_retries--;
}
return 0;
}
static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
char *buf, size_t nbytes,
loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
if (mem_cgroup_is_root(memcg))
return -EINVAL;
return mem_cgroup_force_empty(memcg) ?: nbytes;
}
static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return 1;
}
static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
if (val == 1)
return 0;
pr_warn_once("Non-hierarchical mode is deprecated. "
"Please report your usecase to linux-mm@kvack.org if you "
"depend on this functionality.\n");
return -EINVAL;
}
static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
{
unsigned long val;
if (mem_cgroup_is_root(memcg)) {
/*
* Approximate root's usage from global state. This isn't
* perfect, but the root usage was always an approximation.
*/
val = global_node_page_state(NR_FILE_PAGES) +
global_node_page_state(NR_ANON_MAPPED);
if (swap)
val += total_swap_pages - get_nr_swap_pages();
} else {
if (!swap)
val = page_counter_read(&memcg->memory);
else
val = page_counter_read(&memcg->memsw);
}
return val;
}
enum {
RES_USAGE,
RES_LIMIT,
RES_MAX_USAGE,
RES_FAILCNT,
RES_SOFT_LIMIT,
};
static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct page_counter *counter;
switch (MEMFILE_TYPE(cft->private)) {
case _MEM:
counter = &memcg->memory;
break;
case _MEMSWAP:
counter = &memcg->memsw;
break;
case _KMEM:
counter = &memcg->kmem;
break;
case _TCP:
counter = &memcg->tcpmem;
break;
default:
BUG();
}
switch (MEMFILE_ATTR(cft->private)) {
case RES_USAGE:
if (counter == &memcg->memory)
return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE;
if (counter == &memcg->memsw)
return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
return (u64)page_counter_read(counter) * PAGE_SIZE;
case RES_LIMIT:
return (u64)counter->max * PAGE_SIZE;
case RES_MAX_USAGE:
return (u64)counter->watermark * PAGE_SIZE;
case RES_FAILCNT:
return counter->failcnt;
case RES_SOFT_LIMIT:
return (u64)READ_ONCE(memcg->soft_limit) * PAGE_SIZE;
default:
BUG();
}
}
/*
* This function doesn't do anything useful. Its only job is to provide a read
* handler for a file so that cgroup_file_mode() will add read permissions.
*/
static int mem_cgroup_dummy_seq_show(__always_unused struct seq_file *m,
__always_unused void *v)
{
return -EINVAL;
}
#ifdef CONFIG_MEMCG_KMEM
static int memcg_online_kmem(struct mem_cgroup *memcg)
{
struct obj_cgroup *objcg;
if (mem_cgroup_kmem_disabled())
return 0;
if (unlikely(mem_cgroup_is_root(memcg)))
return 0;
objcg = obj_cgroup_alloc();
if (!objcg)
return -ENOMEM;
objcg->memcg = memcg;
rcu_assign_pointer(memcg->objcg, objcg);
obj_cgroup_get(objcg);
memcg->orig_objcg = objcg;
static_branch_enable(&memcg_kmem_online_key);
memcg->kmemcg_id = memcg->id.id;
return 0;
}
static void memcg_offline_kmem(struct mem_cgroup *memcg)
{
struct mem_cgroup *parent;
if (mem_cgroup_kmem_disabled())
return;
if (unlikely(mem_cgroup_is_root(memcg)))
return;
parent = parent_mem_cgroup(memcg);
if (!parent)
parent = root_mem_cgroup;
memcg_reparent_objcgs(memcg, parent);
/*
* After we have finished memcg_reparent_objcgs(), all list_lrus
* corresponding to this cgroup are guaranteed to remain empty.
* The ordering is imposed by list_lru_node->lock taken by
* memcg_reparent_list_lrus().
*/
memcg_reparent_list_lrus(memcg, parent);
}
#else
static int memcg_online_kmem(struct mem_cgroup *memcg)
{
return 0;
}
static void memcg_offline_kmem(struct mem_cgroup *memcg)
{
}
#endif /* CONFIG_MEMCG_KMEM */
static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
{
int ret;
mutex_lock(&memcg_max_mutex);
ret = page_counter_set_max(&memcg->tcpmem, max);
if (ret)
goto out;
if (!memcg->tcpmem_active) {
/*
* The active flag needs to be written after the static_key
* update. This is what guarantees that the socket activation
* function is the last one to run. See mem_cgroup_sk_alloc()
* for details, and note that we don't mark any socket as
* belonging to this memcg until that flag is up.
*
* We need to do this, because static_keys will span multiple
* sites, but we can't control their order. If we mark a socket
* as accounted, but the accounting functions are not patched in
* yet, we'll lose accounting.
*
* We never race with the readers in mem_cgroup_sk_alloc(),
* because when this value change, the code to process it is not
* patched in yet.
*/
static_branch_inc(&memcg_sockets_enabled_key);
memcg->tcpmem_active = true;
}
out:
mutex_unlock(&memcg_max_mutex);
return ret;
}
/*
* The user of this function is...
* RES_LIMIT.
*/
static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long nr_pages;
int ret;
buf = strstrip(buf);
ret = page_counter_memparse(buf, "-1", &nr_pages);
if (ret)
return ret;
switch (MEMFILE_ATTR(of_cft(of)->private)) {
case RES_LIMIT:
if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
ret = -EINVAL;
break;
}
switch (MEMFILE_TYPE(of_cft(of)->private)) {
case _MEM:
ret = mem_cgroup_resize_max(memcg, nr_pages, false);
break;
case _MEMSWAP:
ret = mem_cgroup_resize_max(memcg, nr_pages, true);
break;
case _KMEM:
pr_warn_once("kmem.limit_in_bytes is deprecated and will be removed. "
"Writing any value to this file has no effect. "
"Please report your usecase to linux-mm@kvack.org if you "
"depend on this functionality.\n");
ret = 0;
break;
case _TCP:
ret = memcg_update_tcp_max(memcg, nr_pages);
break;
}
break;
case RES_SOFT_LIMIT:
if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
ret = -EOPNOTSUPP;
} else {
WRITE_ONCE(memcg->soft_limit, nr_pages);
ret = 0;
}
break;
}
return ret ?: nbytes;
}
static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
struct page_counter *counter;
switch (MEMFILE_TYPE(of_cft(of)->private)) {
case _MEM:
counter = &memcg->memory;
break;
case _MEMSWAP:
counter = &memcg->memsw;
break;
case _KMEM:
counter = &memcg->kmem;
break;
case _TCP:
counter = &memcg->tcpmem;
break;
default:
BUG();
}
switch (MEMFILE_ATTR(of_cft(of)->private)) {
case RES_MAX_USAGE:
page_counter_reset_watermark(counter);
break;
case RES_FAILCNT:
counter->failcnt = 0;
break;
default:
BUG();
}
return nbytes;
}
static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return mem_cgroup_from_css(css)->move_charge_at_immigrate;
}
#ifdef CONFIG_MMU
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. "
"Please report your usecase to linux-mm@kvack.org if you "
"depend on this functionality.\n");
if (val & ~MOVE_MASK)
return -EINVAL;
/*
* No kind of locking is needed in here, because ->can_attach() will
* check this value once in the beginning of the process, and then carry
* on with stale data. This means that changes to this value will only
* affect task migrations starting after the change.
*/
memcg->move_charge_at_immigrate = val;
return 0;
}
#else
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
return -ENOSYS;
}
#endif
#ifdef CONFIG_NUMA
#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
#define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
#define LRU_ALL ((1 << NR_LRU_LISTS) - 1)
static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
int nid, unsigned int lru_mask, bool tree)
{
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
unsigned long nr = 0;
enum lru_list lru;
VM_BUG_ON((unsigned)nid >= nr_node_ids);
for_each_lru(lru) {
if (!(BIT(lru) & lru_mask))
continue;
if (tree)
nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru);
else
nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru);
}
return nr;
}
static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
unsigned int lru_mask,
bool tree)
{
unsigned long nr = 0;
enum lru_list lru;
for_each_lru(lru) {
if (!(BIT(lru) & lru_mask))
continue;
if (tree)
nr += memcg_page_state(memcg, NR_LRU_BASE + lru);
else
nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru);
}
return nr;
}
static int memcg_numa_stat_show(struct seq_file *m, void *v)
{
struct numa_stat {
const char *name;
unsigned int lru_mask;
};
static const struct numa_stat stats[] = {
{ "total", LRU_ALL },
{ "file", LRU_ALL_FILE },
{ "anon", LRU_ALL_ANON },
{ "unevictable", BIT(LRU_UNEVICTABLE) },
};
const struct numa_stat *stat;
int nid;
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
mem_cgroup_flush_stats(memcg);
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
seq_printf(m, "%s=%lu", stat->name,
mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
false));
for_each_node_state(nid, N_MEMORY)
seq_printf(m, " N%d=%lu", nid,
mem_cgroup_node_nr_lru_pages(memcg, nid,
stat->lru_mask, false));
seq_putc(m, '\n');
}
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
seq_printf(m, "hierarchical_%s=%lu", stat->name,
mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
true));
for_each_node_state(nid, N_MEMORY)
seq_printf(m, " N%d=%lu", nid,
mem_cgroup_node_nr_lru_pages(memcg, nid,
stat->lru_mask, true));
seq_putc(m, '\n');
}
return 0;
}
#endif /* CONFIG_NUMA */
static const unsigned int memcg1_stats[] = {
NR_FILE_PAGES,
NR_ANON_MAPPED,
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
NR_ANON_THPS,
#endif
NR_SHMEM,
NR_FILE_MAPPED,
NR_FILE_DIRTY,
NR_WRITEBACK,
WORKINGSET_REFAULT_ANON,
WORKINGSET_REFAULT_FILE,
#ifdef CONFIG_SWAP
MEMCG_SWAP,
NR_SWAPCACHE,
#endif
};
static const char *const memcg1_stat_names[] = {
"cache",
"rss",
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
"rss_huge",
#endif
"shmem",
"mapped_file",
"dirty",
"writeback",
"workingset_refault_anon",
"workingset_refault_file",
#ifdef CONFIG_SWAP
"swap",
"swapcached",
#endif
};
/* Universal VM events cgroup1 shows, original sort order */
static const unsigned int memcg1_events[] = {
PGPGIN,
PGPGOUT,
PGFAULT,
PGMAJFAULT,
};
static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
{
unsigned long memory, memsw;
struct mem_cgroup *mi;
unsigned int i;
BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
mem_cgroup_flush_stats(memcg);
for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
unsigned long nr;
nr = memcg_page_state_local_output(memcg, memcg1_stats[i]);
seq_buf_printf(s, "%s %lu\n", memcg1_stat_names[i], nr);
}
for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
seq_buf_printf(s, "%s %lu\n", vm_event_name(memcg1_events[i]),
memcg_events_local(memcg, memcg1_events[i]));
for (i = 0; i < NR_LRU_LISTS; i++)
seq_buf_printf(s, "%s %lu\n", lru_list_name(i),
memcg_page_state_local(memcg, NR_LRU_BASE + i) *
PAGE_SIZE);
/* Hierarchical information */
memory = memsw = PAGE_COUNTER_MAX;
for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
memory = min(memory, READ_ONCE(mi->memory.max));
memsw = min(memsw, READ_ONCE(mi->memsw.max));
}
seq_buf_printf(s, "hierarchical_memory_limit %llu\n",
(u64)memory * PAGE_SIZE);
seq_buf_printf(s, "hierarchical_memsw_limit %llu\n",
(u64)memsw * PAGE_SIZE);
for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
unsigned long nr;
nr = memcg_page_state_output(memcg, memcg1_stats[i]);
seq_buf_printf(s, "total_%s %llu\n", memcg1_stat_names[i],
(u64)nr);
}
for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
seq_buf_printf(s, "total_%s %llu\n",
vm_event_name(memcg1_events[i]),
(u64)memcg_events(memcg, memcg1_events[i]));
for (i = 0; i < NR_LRU_LISTS; i++)
seq_buf_printf(s, "total_%s %llu\n", lru_list_name(i),
(u64)memcg_page_state(memcg, NR_LRU_BASE + i) *
PAGE_SIZE);
#ifdef CONFIG_DEBUG_VM
{
pg_data_t *pgdat;
struct mem_cgroup_per_node *mz;
unsigned long anon_cost = 0;
unsigned long file_cost = 0;
for_each_online_pgdat(pgdat) {
mz = memcg->nodeinfo[pgdat->node_id];
anon_cost += mz->lruvec.anon_cost;
file_cost += mz->lruvec.file_cost;
}
seq_buf_printf(s, "anon_cost %lu\n", anon_cost);
seq_buf_printf(s, "file_cost %lu\n", file_cost);
}
#endif
}
static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
return mem_cgroup_swappiness(memcg);
}
static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
if (val > 200)
return -EINVAL;
if (!mem_cgroup_is_root(memcg))
WRITE_ONCE(memcg->swappiness, val);
else
WRITE_ONCE(vm_swappiness, val);
return 0;
}
static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
{
struct mem_cgroup_threshold_ary *t;
unsigned long usage;
int i;
rcu_read_lock();
if (!swap)
t = rcu_dereference(memcg->thresholds.primary);
else
t = rcu_dereference(memcg->memsw_thresholds.primary);
if (!t)
goto unlock;
usage = mem_cgroup_usage(memcg, swap);
/*
* current_threshold points to threshold just below or equal to usage.
* If it's not true, a threshold was crossed after last
* call of __mem_cgroup_threshold().
*/
i = t->current_threshold;
/*
* Iterate backward over array of thresholds starting from
* current_threshold and check if a threshold is crossed.
* If none of thresholds below usage is crossed, we read
* only one element of the array here.
*/
for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
eventfd_signal(t->entries[i].eventfd);
/* i = current_threshold + 1 */
i++;
/*
* Iterate forward over array of thresholds starting from
* current_threshold+1 and check if a threshold is crossed.
* If none of thresholds above usage is crossed, we read
* only one element of the array here.
*/
for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
eventfd_signal(t->entries[i].eventfd);
/* Update current_threshold */
t->current_threshold = i - 1;
unlock:
rcu_read_unlock();
}
static void mem_cgroup_threshold(struct mem_cgroup *memcg)
{
while (memcg) {
__mem_cgroup_threshold(memcg, false);
if (do_memsw_account())
__mem_cgroup_threshold(memcg, true);
memcg = parent_mem_cgroup(memcg);
}
}
static int compare_thresholds(const void *a, const void *b)
{
const struct mem_cgroup_threshold *_a = a;
const struct mem_cgroup_threshold *_b = b;
if (_a->threshold > _b->threshold)
return 1;
if (_a->threshold < _b->threshold)
return -1;
return 0;
}
static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
{
struct mem_cgroup_eventfd_list *ev;
spin_lock(&memcg_oom_lock);
list_for_each_entry(ev, &memcg->oom_notify, list)
eventfd_signal(ev->eventfd);
spin_unlock(&memcg_oom_lock);
return 0;
}
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
for_each_mem_cgroup_tree(iter, memcg)
mem_cgroup_oom_notify_cb(iter);
}
static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args, enum res_type type)
{
struct mem_cgroup_thresholds *thresholds;
struct mem_cgroup_threshold_ary *new;
unsigned long threshold;
unsigned long usage;
int i, size, ret;
ret = page_counter_memparse(args, "-1", &threshold);
if (ret)
return ret;
mutex_lock(&memcg->thresholds_lock);
if (type == _MEM) {
thresholds = &memcg->thresholds;
usage = mem_cgroup_usage(memcg, false);
} else if (type == _MEMSWAP) {
thresholds = &memcg->memsw_thresholds;
usage = mem_cgroup_usage(memcg, true);
} else
BUG();
/* Check if a threshold crossed before adding a new one */
if (thresholds->primary)
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
size = thresholds->primary ? thresholds->primary->size + 1 : 1;
/* Allocate memory for new array of thresholds */
new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
if (!new) {
ret = -ENOMEM;
goto unlock;
}
new->size = size;
/* Copy thresholds (if any) to new array */
if (thresholds->primary)
memcpy(new->entries, thresholds->primary->entries,
flex_array_size(new, entries, size - 1));
/* Add new threshold */
new->entries[size - 1].eventfd = eventfd;
new->entries[size - 1].threshold = threshold;
/* Sort thresholds. Registering of new threshold isn't time-critical */
sort(new->entries, size, sizeof(*new->entries),
compare_thresholds, NULL);
/* Find current threshold */
new->current_threshold = -1;
for (i = 0; i < size; i++) {
if (new->entries[i].threshold <= usage) {
/*
* new->current_threshold will not be used until
* rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++new->current_threshold;
} else
break;
}
/* Free old spare buffer and save old primary buffer as spare */
kfree(thresholds->spare);
thresholds->spare = thresholds->primary;
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
synchronize_rcu();
unlock:
mutex_unlock(&memcg->thresholds_lock);
return ret;
}
static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args)
{
return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
}
static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args)
{
return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
}
static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, enum res_type type)
{
struct mem_cgroup_thresholds *thresholds;
struct mem_cgroup_threshold_ary *new;
unsigned long usage;
int i, j, size, entries;
mutex_lock(&memcg->thresholds_lock);
if (type == _MEM) {
thresholds = &memcg->thresholds;
usage = mem_cgroup_usage(memcg, false);
} else if (type == _MEMSWAP) {
thresholds = &memcg->memsw_thresholds;
usage = mem_cgroup_usage(memcg, true);
} else
BUG();
if (!thresholds->primary)
goto unlock;
/* Check if a threshold crossed before removing */
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
/* Calculate new number of threshold */
size = entries = 0;
for (i = 0; i < thresholds->primary->size; i++) {
if (thresholds->primary->entries[i].eventfd != eventfd)
size++;
else
entries++;
}
new = thresholds->spare;
/* If no items related to eventfd have been cleared, nothing to do */
if (!entries)
goto unlock;
/* Set thresholds array to NULL if we don't have thresholds */
if (!size) {
kfree(new);
new = NULL;
goto swap_buffers;
}
new->size = size;
/* Copy thresholds and find current threshold */
new->current_threshold = -1;
for (i = 0, j = 0; i < thresholds->primary->size; i++) {
if (thresholds->primary->entries[i].eventfd == eventfd)
continue;
new->entries[j] = thresholds->primary->entries[i];
if (new->entries[j].threshold <= usage) {
/*
* new->current_threshold will not be used
* until rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++new->current_threshold;
}
j++;
}
swap_buffers:
/* Swap primary and spare array */
thresholds->spare = thresholds->primary;
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
synchronize_rcu();
/* If all events are unregistered, free the spare array */
if (!new) {
kfree(thresholds->spare);
thresholds->spare = NULL;
}
unlock:
mutex_unlock(&memcg->thresholds_lock);
}
static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd)
{
return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
}
static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd)
{
return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
}
static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args)
{
struct mem_cgroup_eventfd_list *event;
event = kmalloc(sizeof(*event), GFP_KERNEL);
if (!event)
return -ENOMEM;
spin_lock(&memcg_oom_lock);
event->eventfd = eventfd;
list_add(&event->list, &memcg->oom_notify);
/* already in OOM ? */
if (memcg->under_oom)
eventfd_signal(eventfd);
spin_unlock(&memcg_oom_lock);
return 0;
}
static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd)
{
struct mem_cgroup_eventfd_list *ev, *tmp;
spin_lock(&memcg_oom_lock);
list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
if (ev->eventfd == eventfd) {
list_del(&ev->list);
kfree(ev);
}
}
spin_unlock(&memcg_oom_lock);
}
static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
seq_printf(sf, "oom_kill_disable %d\n", READ_ONCE(memcg->oom_kill_disable));
seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
seq_printf(sf, "oom_kill %lu\n",
atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
return 0;
}
static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
/* cannot set to root cgroup and only 0 and 1 are allowed */
if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1)))
return -EINVAL;
WRITE_ONCE(memcg->oom_kill_disable, val);
if (!val)
memcg_oom_recover(memcg);
return 0;
}
#ifdef CONFIG_CGROUP_WRITEBACK
#include <trace/events/writeback.h>
static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
{
return wb_domain_init(&memcg->cgwb_domain, gfp);
}
static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
{
wb_domain_exit(&memcg->cgwb_domain);
}
static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
{
wb_domain_size_changed(&memcg->cgwb_domain);
}
struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
if (!memcg->css.parent)
return NULL;
return &memcg->cgwb_domain;
}
/**
* mem_cgroup_wb_stats - retrieve writeback related stats from its memcg
* @wb: bdi_writeback in question
* @pfilepages: out parameter for number of file pages
* @pheadroom: out parameter for number of allocatable pages according to memcg
* @pdirty: out parameter for number of dirty pages
* @pwriteback: out parameter for number of pages under writeback
*
* Determine the numbers of file, headroom, dirty, and writeback pages in
* @wb's memcg. File, dirty and writeback are self-explanatory. Headroom
* is a bit more involved.
*
* A memcg's headroom is "min(max, high) - used". In the hierarchy, the
* headroom is calculated as the lowest headroom of itself and the
* ancestors. Note that this doesn't consider the actual amount of
* available memory in the system. The caller should further cap
* *@pheadroom accordingly.
*/
void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
unsigned long *pheadroom, unsigned long *pdirty,
unsigned long *pwriteback)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
struct mem_cgroup *parent;
mem_cgroup_flush_stats_ratelimited(memcg);
*pdirty = memcg_page_state(memcg, NR_FILE_DIRTY);
*pwriteback = memcg_page_state(memcg, NR_WRITEBACK);
*pfilepages = memcg_page_state(memcg, NR_INACTIVE_FILE) +
memcg_page_state(memcg, NR_ACTIVE_FILE);
*pheadroom = PAGE_COUNTER_MAX;
while ((parent = parent_mem_cgroup(memcg))) {
unsigned long ceiling = min(READ_ONCE(memcg->memory.max),
READ_ONCE(memcg->memory.high));
unsigned long used = page_counter_read(&memcg->memory);
*pheadroom = min(*pheadroom, ceiling - min(ceiling, used));
memcg = parent;
}
}
/*
* Foreign dirty flushing
*
* There's an inherent mismatch between memcg and writeback. The former
* tracks ownership per-page while the latter per-inode. This was a
* deliberate design decision because honoring per-page ownership in the
* writeback path is complicated, may lead to higher CPU and IO overheads
* and deemed unnecessary given that write-sharing an inode across
* different cgroups isn't a common use-case.
*
* Combined with inode majority-writer ownership switching, this works well
* enough in most cases but there are some pathological cases. For
* example, let's say there are two cgroups A and B which keep writing to
* different but confined parts of the same inode. B owns the inode and
* A's memory is limited far below B's. A's dirty ratio can rise enough to
* trigger balance_dirty_pages() sleeps but B's can be low enough to avoid
* triggering background writeback. A will be slowed down without a way to
* make writeback of the dirty pages happen.
*
* Conditions like the above can lead to a cgroup getting repeatedly and
* severely throttled after making some progress after each
* dirty_expire_interval while the underlying IO device is almost
* completely idle.
*
* Solving this problem completely requires matching the ownership tracking
* granularities between memcg and writeback in either direction. However,
* the more egregious behaviors can be avoided by simply remembering the
* most recent foreign dirtying events and initiating remote flushes on
* them when local writeback isn't enough to keep the memory clean enough.
*
* The following two functions implement such mechanism. When a foreign
* page - a page whose memcg and writeback ownerships don't match - is
* dirtied, mem_cgroup_track_foreign_dirty() records the inode owning
* bdi_writeback on the page owning memcg. When balance_dirty_pages()
* decides that the memcg needs to sleep due to high dirty ratio, it calls
* mem_cgroup_flush_foreign() which queues writeback on the recorded
* foreign bdi_writebacks which haven't expired. Both the numbers of
* recorded bdi_writebacks and concurrent in-flight foreign writebacks are
* limited to MEMCG_CGWB_FRN_CNT.
*
* The mechanism only remembers IDs and doesn't hold any object references.
* As being wrong occasionally doesn't matter, updates and accesses to the
* records are lockless and racy.
*/
void mem_cgroup_track_foreign_dirty_slowpath(struct folio *folio,
struct bdi_writeback *wb)
{
struct mem_cgroup *memcg = folio_memcg(folio);
struct memcg_cgwb_frn *frn;
u64 now = get_jiffies_64();
u64 oldest_at = now;
int oldest = -1;
int i;
trace_track_foreign_dirty(folio, wb);
/*
* Pick the slot to use. If there is already a slot for @wb, keep
* using it. If not replace the oldest one which isn't being
* written out.
*/
for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) {
frn = &memcg->cgwb_frn[i];
if (frn->bdi_id == wb->bdi->id &&
frn->memcg_id == wb->memcg_css->id)
break;
if (time_before64(frn->at, oldest_at) &&
atomic_read(&frn->done.cnt) == 1) {
oldest = i;
oldest_at = frn->at;
}
}
if (i < MEMCG_CGWB_FRN_CNT) {
/*
* Re-using an existing one. Update timestamp lazily to
* avoid making the cacheline hot. We want them to be
* reasonably up-to-date and significantly shorter than
* dirty_expire_interval as that's what expires the record.
* Use the shorter of 1s and dirty_expire_interval / 8.
*/
unsigned long update_intv =
min_t(unsigned long, HZ,
msecs_to_jiffies(dirty_expire_interval * 10) / 8);
if (time_before64(frn->at, now - update_intv))
frn->at = now;
} else if (oldest >= 0) {
/* replace the oldest free one */
frn = &memcg->cgwb_frn[oldest];
frn->bdi_id = wb->bdi->id;
frn->memcg_id = wb->memcg_css->id;
frn->at = now;
}
}
/* issue foreign writeback flushes for recorded foreign dirtying events */
void mem_cgroup_flush_foreign(struct bdi_writeback *wb)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
unsigned long intv = msecs_to_jiffies(dirty_expire_interval * 10);
u64 now = jiffies_64;
int i;
for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) {
struct memcg_cgwb_frn *frn = &memcg->cgwb_frn[i];
/*
* If the record is older than dirty_expire_interval,
* writeback on it has already started. No need to kick it
* off again. Also, don't start a new one if there's
* already one in flight.
*/
if (time_after64(frn->at, now - intv) &&
atomic_read(&frn->done.cnt) == 1) {
frn->at = 0;
trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id);
cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id,
WB_REASON_FOREIGN_FLUSH,
&frn->done);
}
}
}
#else /* CONFIG_CGROUP_WRITEBACK */
static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
{
return 0;
}
static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
{
}
static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
{
}
#endif /* CONFIG_CGROUP_WRITEBACK */
/*
* DO NOT USE IN NEW FILES.
*
* "cgroup.event_control" implementation.
*
* This is way over-engineered. It tries to support fully configurable
* events for each user. Such level of flexibility is completely
* unnecessary especially in the light of the planned unified hierarchy.
*
* Please deprecate this and replace with something simpler if at all
* possible.
*/
/*
* Unregister event and free resources.
*
* Gets called from workqueue.
*/
static void memcg_event_remove(struct work_struct *work)
{
struct mem_cgroup_event *event =
container_of(work, struct mem_cgroup_event, remove);
struct mem_cgroup *memcg = event->memcg;
remove_wait_queue(event->wqh, &event->wait);
event->unregister_event(memcg, event->eventfd);
/* Notify userspace the event is going away. */
eventfd_signal(event->eventfd);
eventfd_ctx_put(event->eventfd);
kfree(event);
css_put(&memcg->css);
}
/*
* Gets called on EPOLLHUP on eventfd when user closes it.
*
* Called with wqh->lock held and interrupts disabled.
*/
static int memcg_event_wake(wait_queue_entry_t *wait, unsigned mode,
int sync, void *key)
{
struct mem_cgroup_event *event =
container_of(wait, struct mem_cgroup_event, wait);
struct mem_cgroup *memcg = event->memcg;
__poll_t flags = key_to_poll(key);
if (flags & EPOLLHUP) {
/*
* If the event has been detached at cgroup removal, we
* can simply return knowing the other side will cleanup
* for us.
*
* We can't race against event freeing since the other
* side will require wqh->lock via remove_wait_queue(),
* which we hold.
*/
spin_lock(&memcg->event_list_lock);
if (!list_empty(&event->list)) {
list_del_init(&event->list);
/*
* We are in atomic context, but cgroup_event_remove()
* may sleep, so we have to call it in workqueue.
*/
schedule_work(&event->remove);
}
spin_unlock(&memcg->event_list_lock);
}
return 0;
}
static void memcg_event_ptable_queue_proc(struct file *file,
wait_queue_head_t *wqh, poll_table *pt)
{
struct mem_cgroup_event *event =
container_of(pt, struct mem_cgroup_event, pt);
event->wqh = wqh;
add_wait_queue(wqh, &event->wait);
}
/*
* DO NOT USE IN NEW FILES.
*
* Parse input and register new cgroup event handler.
*
* Input must be in format '<event_fd> <control_fd> <args>'.
* Interpretation of args is defined by control file implementation.
*/
static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct cgroup_subsys_state *css = of_css(of);
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup_event *event;
struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
struct fd efile;
struct fd cfile;
struct dentry *cdentry;
const char *name;
char *endp;
int ret;
if (IS_ENABLED(CONFIG_PREEMPT_RT))
return -EOPNOTSUPP;
buf = strstrip(buf);
efd = simple_strtoul(buf, &endp, 10);
if (*endp != ' ')
return -EINVAL;
buf = endp + 1;
cfd = simple_strtoul(buf, &endp, 10);
if ((*endp != ' ') && (*endp != '\0'))
return -EINVAL;
buf = endp + 1;
event = kzalloc(sizeof(*event), GFP_KERNEL);
if (!event)
return -ENOMEM;
event->memcg = memcg;
INIT_LIST_HEAD(&event->list);
init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
init_waitqueue_func_entry(&event->wait, memcg_event_wake);
INIT_WORK(&event->remove, memcg_event_remove);
efile = fdget(efd);
if (!efile.file) {
ret = -EBADF;
goto out_kfree;
}
event->eventfd = eventfd_ctx_fileget(efile.file);
if (IS_ERR(event->eventfd)) {
ret = PTR_ERR(event->eventfd);
goto out_put_efile;
}
cfile = fdget(cfd);
if (!cfile.file) {
ret = -EBADF;
goto out_put_eventfd;
}
/* the process need read permission on control file */
/* AV: shouldn't we check that it's been opened for read instead? */
ret = file_permission(cfile.file, MAY_READ);
if (ret < 0)
goto out_put_cfile;
/*
* The control file must be a regular cgroup1 file. As a regular cgroup
* file can't be renamed, it's safe to access its name afterwards.
*/
cdentry = cfile.file->f_path.dentry;
if (cdentry->d_sb->s_type != &cgroup_fs_type || !d_is_reg(cdentry)) {
ret = -EINVAL;
goto out_put_cfile;
}
/*
* Determine the event callbacks and set them in @event. This used
* to be done via struct cftype but cgroup core no longer knows
* about these events. The following is crude but the whole thing
* is for compatibility anyway.
*
* DO NOT ADD NEW FILES.
*/
name = cdentry->d_name.name;
if (!strcmp(name, "memory.usage_in_bytes")) {
event->register_event = mem_cgroup_usage_register_event;
event->unregister_event = mem_cgroup_usage_unregister_event;
} else if (!strcmp(name, "memory.oom_control")) {
event->register_event = mem_cgroup_oom_register_event;
event->unregister_event = mem_cgroup_oom_unregister_event;
} else if (!strcmp(name, "memory.pressure_level")) {
event->register_event = vmpressure_register_event;
event->unregister_event = vmpressure_unregister_event;
} else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
event->register_event = memsw_cgroup_usage_register_event;
event->unregister_event = memsw_cgroup_usage_unregister_event;
} else {
ret = -EINVAL;
goto out_put_cfile;
}
/*
* Verify @cfile should belong to @css. Also, remaining events are
* automatically removed on cgroup destruction but the removal is
* asynchronous, so take an extra ref on @css.
*/
cfile_css = css_tryget_online_from_dir(cdentry->d_parent,
&memory_cgrp_subsys);
ret = -EINVAL;
if (IS_ERR(cfile_css))
goto out_put_cfile;
if (cfile_css != css) {
css_put(cfile_css);
goto out_put_cfile;
}
ret = event->register_event(memcg, event->eventfd, buf);
if (ret)
goto out_put_css;
vfs_poll(efile.file, &event->pt);
spin_lock_irq(&memcg->event_list_lock);
list_add(&event->list, &memcg->event_list);
spin_unlock_irq(&memcg->event_list_lock);
fdput(cfile);
fdput(efile);
return nbytes;
out_put_css:
css_put(css);
out_put_cfile:
fdput(cfile);
out_put_eventfd:
eventfd_ctx_put(event->eventfd);
out_put_efile:
fdput(efile);
out_kfree:
kfree(event);
return ret;
}
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
static int mem_cgroup_slab_show(struct seq_file *m, void *p)
{
/*
* Deprecated.
* Please, take a look at tools/cgroup/memcg_slabinfo.py .
*/
return 0;
}
#endif
static int memory_stat_show(struct seq_file *m, void *v);
static struct cftype mem_cgroup_legacy_files[] = {
{
.name = "usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
.write = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "soft_limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
.write = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "failcnt",
.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "stat",
.seq_show = memory_stat_show,
},
{
.name = "force_empty",
.write = mem_cgroup_force_empty_write,
},
{
.name = "use_hierarchy",
.write_u64 = mem_cgroup_hierarchy_write,
.read_u64 = mem_cgroup_hierarchy_read,
},
{
.name = "cgroup.event_control", /* XXX: for compat */
.write = memcg_write_event_control,
.flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
},
{
.name = "swappiness",
.read_u64 = mem_cgroup_swappiness_read,
.write_u64 = mem_cgroup_swappiness_write,
},
{
.name = "move_charge_at_immigrate",
.read_u64 = mem_cgroup_move_charge_read,
.write_u64 = mem_cgroup_move_charge_write,
},
{
.name = "oom_control",
.seq_show = mem_cgroup_oom_control_read,
.write_u64 = mem_cgroup_oom_control_write,
},
{
.name = "pressure_level",
.seq_show = mem_cgroup_dummy_seq_show,
},
#ifdef CONFIG_NUMA
{
.name = "numa_stat",
.seq_show = memcg_numa_stat_show,
},
#endif
{
.name = "kmem.limit_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
.write = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.failcnt",
.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_SLUB_DEBUG)
{
.name = "kmem.slabinfo",
.seq_show = mem_cgroup_slab_show,
},
#endif
{
.name = "kmem.tcp.limit_in_bytes",
.private = MEMFILE_PRIVATE(_TCP, RES_LIMIT),
.write = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.tcp.usage_in_bytes",
.private = MEMFILE_PRIVATE(_TCP, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.tcp.failcnt",
.private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.tcp.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{ }, /* terminate */
};
/*
* Private memory cgroup IDR
*
* Swap-out records and page cache shadow entries need to store memcg
* references in constrained space, so we maintain an ID space that is
* limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of
* memory-controlled cgroups to 64k.
*
* However, there usually are many references to the offline CSS after
* the cgroup has been destroyed, such as page cache or reclaimable
* slab objects, that don't need to hang on to the ID. We want to keep
* those dead CSS from occupying IDs, or we might quickly exhaust the
* relatively small ID space and prevent the creation of new cgroups
* even when there are much fewer than 64k cgroups - possibly none.
*
* Maintain a private 16-bit ID space for memcg, and allow the ID to
* be freed and recycled when it's no longer needed, which is usually
* when the CSS is offlined.
*
* The only exception to that are records of swapped out tmpfs/shmem
* pages that need to be attributed to live ancestors on swapin. But
* those references are manageable from userspace.
*/
#define MEM_CGROUP_ID_MAX ((1UL << MEM_CGROUP_ID_SHIFT) - 1)
static DEFINE_IDR(mem_cgroup_idr);
static void mem_cgroup_id_remove(struct mem_cgroup *memcg)
{
if (memcg->id.id > 0) {
idr_remove(&mem_cgroup_idr, memcg->id.id);
memcg->id.id = 0;
}
}
static void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg,
unsigned int n)
{
refcount_add(n, &memcg->id.ref);
}
static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
{
if (refcount_sub_and_test(n, &memcg->id.ref)) {
mem_cgroup_id_remove(memcg);
/* Memcg ID pins CSS */
css_put(&memcg->css);
}
}
static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)
{
mem_cgroup_id_put_many(memcg, 1);
}
/**
* mem_cgroup_from_id - look up a memcg from a memcg id
* @id: the memcg id to look up
*
* Caller must hold rcu_read_lock().
*/
struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
WARN_ON_ONCE(!rcu_read_lock_held());
return idr_find(&mem_cgroup_idr, id);
}
#ifdef CONFIG_SHRINKER_DEBUG
struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)
{
struct cgroup *cgrp;
struct cgroup_subsys_state *css;
struct mem_cgroup *memcg;
cgrp = cgroup_get_from_id(ino);
if (IS_ERR(cgrp))
return ERR_CAST(cgrp);
css = cgroup_get_e_css(cgrp, &memory_cgrp_subsys);
if (css)
memcg = container_of(css, struct mem_cgroup, css);
else
memcg = ERR_PTR(-ENOENT);
cgroup_put(cgrp);
return memcg;
}
#endif
static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
{
struct mem_cgroup_per_node *pn;
pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, node);
if (!pn)
return 1;
pn->lruvec_stats_percpu = alloc_percpu_gfp(struct lruvec_stats_percpu,
GFP_KERNEL_ACCOUNT);
if (!pn->lruvec_stats_percpu) {
kfree(pn);
return 1;
}
lruvec_init(&pn->lruvec);
pn->memcg = memcg;
memcg->nodeinfo[node] = pn;
return 0;
}
static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
{
struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
if (!pn)
return;
free_percpu(pn->lruvec_stats_percpu);
kfree(pn);
}
static void __mem_cgroup_free(struct mem_cgroup *memcg)
{
int node;
if (memcg->orig_objcg)
obj_cgroup_put(memcg->orig_objcg);
for_each_node(node)
free_mem_cgroup_per_node_info(memcg, node);
kfree(memcg->vmstats);
free_percpu(memcg->vmstats_percpu);
kfree(memcg);
}
static void mem_cgroup_free(struct mem_cgroup *memcg)
{
lru_gen_exit_memcg(memcg);
memcg_wb_domain_exit(memcg);
__mem_cgroup_free(memcg);
}
static struct mem_cgroup *mem_cgroup_alloc(struct mem_cgroup *parent)
{
struct memcg_vmstats_percpu *statc, *pstatc;
struct mem_cgroup *memcg;
int node, cpu;
int __maybe_unused i;
long error = -ENOMEM;
memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL);
if (!memcg)
return ERR_PTR(error);
memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
1, MEM_CGROUP_ID_MAX + 1, GFP_KERNEL);
if (memcg->id.id < 0) {
error = memcg->id.id;
goto fail;
}
memcg->vmstats = kzalloc(sizeof(struct memcg_vmstats), GFP_KERNEL);
if (!memcg->vmstats)
goto fail;
memcg->vmstats_percpu = alloc_percpu_gfp(struct memcg_vmstats_percpu,
GFP_KERNEL_ACCOUNT);
if (!memcg->vmstats_percpu)
goto fail;
for_each_possible_cpu(cpu) {
if (parent)
pstatc = per_cpu_ptr(parent->vmstats_percpu, cpu);
statc = per_cpu_ptr(memcg->vmstats_percpu, cpu);
statc->parent = parent ? pstatc : NULL;
statc->vmstats = memcg->vmstats;
}
for_each_node(node)
if (alloc_mem_cgroup_per_node_info(memcg, node))
goto fail;
if (memcg_wb_domain_init(memcg, GFP_KERNEL))
goto fail;
INIT_WORK(&memcg->high_work, high_work_func);
INIT_LIST_HEAD(&memcg->oom_notify);
mutex_init(&memcg->thresholds_lock);
spin_lock_init(&memcg->move_lock);
vmpressure_init(&memcg->vmpressure);
INIT_LIST_HEAD(&memcg->event_list);
spin_lock_init(&memcg->event_list_lock);
memcg->socket_pressure = jiffies;
#ifdef CONFIG_MEMCG_KMEM
memcg->kmemcg_id = -1;
INIT_LIST_HEAD(&memcg->objcg_list);
#endif
#ifdef CONFIG_CGROUP_WRITEBACK
INIT_LIST_HEAD(&memcg->cgwb_list);
for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++)
memcg->cgwb_frn[i].done =
__WB_COMPLETION_INIT(&memcg_cgwb_frn_waitq);
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
spin_lock_init(&memcg->deferred_split_queue.split_queue_lock);
INIT_LIST_HEAD(&memcg->deferred_split_queue.split_queue);
memcg->deferred_split_queue.split_queue_len = 0;
#endif
lru_gen_init_memcg(memcg);
return memcg;
fail:
mem_cgroup_id_remove(memcg);
__mem_cgroup_free(memcg);
return ERR_PTR(error);
}
static struct cgroup_subsys_state * __ref
mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct mem_cgroup *parent = mem_cgroup_from_css(parent_css);
struct mem_cgroup *memcg, *old_memcg;
old_memcg = set_active_memcg(parent);
memcg = mem_cgroup_alloc(parent);
set_active_memcg(old_memcg);
if (IS_ERR(memcg))
return ERR_CAST(memcg);
page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
memcg->zswap_max = PAGE_COUNTER_MAX;
WRITE_ONCE(memcg->zswap_writeback,
!parent || READ_ONCE(parent->zswap_writeback));
#endif
page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
if (parent) {
WRITE_ONCE(memcg->swappiness, mem_cgroup_swappiness(parent));
WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable));
page_counter_init(&memcg->memory, &parent->memory);
page_counter_init(&memcg->swap, &parent->swap);
page_counter_init(&memcg->kmem, &parent->kmem);
page_counter_init(&memcg->tcpmem, &parent->tcpmem);
} else {
init_memcg_events();
page_counter_init(&memcg->memory, NULL);
page_counter_init(&memcg->swap, NULL);
page_counter_init(&memcg->kmem, NULL);
page_counter_init(&memcg->tcpmem, NULL);
root_mem_cgroup = memcg;
return &memcg->css;
}
if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
static_branch_inc(&memcg_sockets_enabled_key);
#if defined(CONFIG_MEMCG_KMEM)
if (!cgroup_memory_nobpf)
static_branch_inc(&memcg_bpf_enabled_key);
#endif
return &memcg->css;
}
static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
if (memcg_online_kmem(memcg))
goto remove_id;
/*
* A memcg must be visible for expand_shrinker_info()
* by the time the maps are allocated. So, we allocate maps
* here, when for_each_mem_cgroup() can't skip it.
*/
if (alloc_shrinker_info(memcg))
goto offline_kmem;
if (unlikely(mem_cgroup_is_root(memcg)) && !mem_cgroup_disabled())
queue_delayed_work(system_unbound_wq, &stats_flush_dwork,
FLUSH_TIME);
lru_gen_online_memcg(memcg);
/* Online state pins memcg ID, memcg ID pins CSS */
refcount_set(&memcg->id.ref, 1);
css_get(css);
/*
* Ensure mem_cgroup_from_id() works once we're fully online.
*
* We could do this earlier and require callers to filter with
* css_tryget_online(). But right now there are no users that
* need earlier access, and the workingset code relies on the
* cgroup tree linkage (mem_cgroup_get_nr_swap_pages()). So
* publish it here at the end of onlining. This matches the
* regular ID destruction during offlining.
*/
idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
return 0;
offline_kmem:
memcg_offline_kmem(memcg);
remove_id:
mem_cgroup_id_remove(memcg);
return -ENOMEM;
}
static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup_event *event, *tmp;
/*
* Unregister events and notify userspace.
* Notify userspace about cgroup removing only after rmdir of cgroup
* directory to avoid race between userspace and kernelspace.
*/
spin_lock_irq(&memcg->event_list_lock);
list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
list_del_init(&event->list);
schedule_work(&event->remove);
}
spin_unlock_irq(&memcg->event_list_lock);
page_counter_set_min(&memcg->memory, 0);
page_counter_set_low(&memcg->memory, 0);
zswap_memcg_offline_cleanup(memcg);
memcg_offline_kmem(memcg);
reparent_shrinker_deferred(memcg);
wb_memcg_offline(memcg);
lru_gen_offline_memcg(memcg);
drain_all_stock(memcg);
mem_cgroup_id_put(memcg);
}
static void mem_cgroup_css_released(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
invalidate_reclaim_iterators(memcg);
lru_gen_release_memcg(memcg);
}
static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
int __maybe_unused i;
#ifdef CONFIG_CGROUP_WRITEBACK
for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++)
wb_wait_for_completion(&memcg->cgwb_frn[i].done);
#endif
if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
static_branch_dec(&memcg_sockets_enabled_key);
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_active)
static_branch_dec(&memcg_sockets_enabled_key);
#if defined(CONFIG_MEMCG_KMEM)
if (!cgroup_memory_nobpf)
static_branch_dec(&memcg_bpf_enabled_key);
#endif
vmpressure_cleanup(&memcg->vmpressure);
cancel_work_sync(&memcg->high_work);
mem_cgroup_remove_from_trees(memcg);
free_shrinker_info(memcg);
mem_cgroup_free(memcg);
}
/**
* mem_cgroup_css_reset - reset the states of a mem_cgroup
* @css: the target css
*
* Reset the states of the mem_cgroup associated with @css. This is
* invoked when the userland requests disabling on the default hierarchy
* but the memcg is pinned through dependency. The memcg should stop
* applying policies and should revert to the vanilla state as it may be
* made visible again.
*
* The current implementation only resets the essential configurations.
* This needs to be expanded to cover all the visible parts.
*/
static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
page_counter_set_min(&memcg->memory, 0);
page_counter_set_low(&memcg->memory, 0);
page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
WRITE_ONCE(memcg->soft_limit, PAGE_COUNTER_MAX);
page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
memcg_wb_domain_size_changed(memcg);
}
static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = parent_mem_cgroup(memcg);
struct memcg_vmstats_percpu *statc;
long delta, delta_cpu, v;
int i, nid;
statc = per_cpu_ptr(memcg->vmstats_percpu, cpu);
for (i = 0; i < MEMCG_NR_STAT; i++) {
/*
* Collect the aggregated propagation counts of groups
* below us. We're in a per-cpu loop here and this is
* a global counter, so the first cycle will get them.
*/
delta = memcg->vmstats->state_pending[i];
if (delta)
memcg->vmstats->state_pending[i] = 0;
/* Add CPU changes on this level since the last flush */
delta_cpu = 0;
v = READ_ONCE(statc->state[i]);
if (v != statc->state_prev[i]) {
delta_cpu = v - statc->state_prev[i];
delta += delta_cpu;
statc->state_prev[i] = v;
}
/* Aggregate counts on this level and propagate upwards */
if (delta_cpu)
memcg->vmstats->state_local[i] += delta_cpu;
if (delta) {
memcg->vmstats->state[i] += delta;
if (parent)
parent->vmstats->state_pending[i] += delta;
}
}
for (i = 0; i < NR_MEMCG_EVENTS; i++) {
delta = memcg->vmstats->events_pending[i];
if (delta)
memcg->vmstats->events_pending[i] = 0;
delta_cpu = 0;
v = READ_ONCE(statc->events[i]);
if (v != statc->events_prev[i]) {
delta_cpu = v - statc->events_prev[i];
delta += delta_cpu;
statc->events_prev[i] = v;
}
if (delta_cpu)
memcg->vmstats->events_local[i] += delta_cpu;
if (delta) {
memcg->vmstats->events[i] += delta;
if (parent)
parent->vmstats->events_pending[i] += delta;
}
}
for_each_node_state(nid, N_MEMORY) {
struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid];
struct mem_cgroup_per_node *ppn = NULL;
struct lruvec_stats_percpu *lstatc;
if (parent)
ppn = parent->nodeinfo[nid];
lstatc = per_cpu_ptr(pn->lruvec_stats_percpu, cpu);
for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
delta = pn->lruvec_stats.state_pending[i];
if (delta)
pn->lruvec_stats.state_pending[i] = 0;
delta_cpu = 0;
v = READ_ONCE(lstatc->state[i]);
if (v != lstatc->state_prev[i]) {
delta_cpu = v - lstatc->state_prev[i];
delta += delta_cpu;
lstatc->state_prev[i] = v;
}
if (delta_cpu)
pn->lruvec_stats.state_local[i] += delta_cpu;
if (delta) {
pn->lruvec_stats.state[i] += delta;
if (ppn)
ppn->lruvec_stats.state_pending[i] += delta;
}
}
}
statc->stats_updates = 0;
/* We are in a per-cpu loop here, only do the atomic write once */
if (atomic64_read(&memcg->vmstats->stats_updates))
atomic64_set(&memcg->vmstats->stats_updates, 0);
}
#ifdef CONFIG_MMU
/* Handlers for move charge at task migration. */
static int mem_cgroup_do_precharge(unsigned long count)
{
int ret;
/* Try a single bulk charge without reclaim first, kswapd may wake */
ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count);
if (!ret) {
mc.precharge += count;
return ret;
}
/* Try charges one by one with reclaim, but do not retry */
while (count--) {
ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1);
if (ret)
return ret;
mc.precharge++;
cond_resched();
}
return 0;
}
union mc_target {
struct folio *folio;
swp_entry_t ent;
};
enum mc_target_type {
MC_TARGET_NONE = 0,
MC_TARGET_PAGE,
MC_TARGET_SWAP,
MC_TARGET_DEVICE,
};
static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent)
{
struct page *page = vm_normal_page(vma, addr, ptent);
if (!page)
return NULL;
if (PageAnon(page)) {
if (!(mc.flags & MOVE_ANON))
return NULL;
} else {
if (!(mc.flags & MOVE_FILE))
return NULL;
}
get_page(page);
return page;
}
#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE)
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
pte_t ptent, swp_entry_t *entry)
{
struct page *page = NULL;
swp_entry_t ent = pte_to_swp_entry(ptent);
if (!(mc.flags & MOVE_ANON))
return NULL;
/*
* Handle device private pages that are not accessible by the CPU, but
* stored as special swap entries in the page table.
*/
if (is_device_private_entry(ent)) {
page = pfn_swap_entry_to_page(ent);
if (!get_page_unless_zero(page))
return NULL;
return page;
}
if (non_swap_entry(ent))
return NULL;
/*
* Because swap_cache_get_folio() updates some statistics counter,
* we call find_get_page() with swapper_space directly.
*/
page = find_get_page(swap_address_space(ent), swp_offset(ent));
entry->val = ent.val;
return page;
}
#else
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
pte_t ptent, swp_entry_t *entry)
{
return NULL;
}
#endif
static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent)
{
unsigned long index;
struct folio *folio;
if (!vma->vm_file) /* anonymous vma */
return NULL;
if (!(mc.flags & MOVE_FILE))
return NULL;
/* folio is moved even if it's not RSS of this task(page-faulted). */
/* shmem/tmpfs may report page out on swap: account for that too. */
index = linear_page_index(vma, addr);
folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index);
if (IS_ERR(folio))
return NULL;
return folio_file_page(folio, index);
}
/**
* mem_cgroup_move_account - move account of the folio
* @folio: The folio.
* @compound: charge the page as compound or small page
* @from: mem_cgroup which the folio is moved from.
* @to: mem_cgroup which the folio is moved to. @from != @to.
*
* The folio must be locked and not on the LRU.
*
* This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
* from old cgroup.
*/
static int mem_cgroup_move_account(struct folio *folio,
bool compound,
struct mem_cgroup *from,
struct mem_cgroup *to)
{
struct lruvec *from_vec, *to_vec;
struct pglist_data *pgdat;
unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1;
int nid, ret;
VM_BUG_ON(from == to);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
VM_BUG_ON(compound && !folio_test_large(folio));
ret = -EINVAL;
if (folio_memcg(folio) != from)
goto out;
pgdat = folio_pgdat(folio);
from_vec = mem_cgroup_lruvec(from, pgdat);
to_vec = mem_cgroup_lruvec(to, pgdat);
folio_memcg_lock(folio);
if (folio_test_anon(folio)) {
if (folio_mapped(folio)) {
__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
if (folio_test_pmd_mappable(folio)) {
__mod_lruvec_state(from_vec, NR_ANON_THPS,
-nr_pages);
__mod_lruvec_state(to_vec, NR_ANON_THPS,
nr_pages);
}
}
} else {
__mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
__mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages);
if (folio_test_swapbacked(folio)) {
__mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages);
__mod_lruvec_state(to_vec, NR_SHMEM, nr_pages);
}
if (folio_mapped(folio)) {
__mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
__mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
}
if (folio_test_dirty(folio)) {
struct address_space *mapping = folio_mapping(folio);
if (mapping_can_writeback(mapping)) {
__mod_lruvec_state(from_vec, NR_FILE_DIRTY,
-nr_pages);
__mod_lruvec_state(to_vec, NR_FILE_DIRTY,
nr_pages);
}
}
}
#ifdef CONFIG_SWAP
if (folio_test_swapcache(folio)) {
__mod_lruvec_state(from_vec, NR_SWAPCACHE, -nr_pages);
__mod_lruvec_state(to_vec, NR_SWAPCACHE, nr_pages);
}
#endif
if (folio_test_writeback(folio)) {
__mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages);
__mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);
}
/*
* All state has been migrated, let's switch to the new memcg.
*
* It is safe to change page's memcg here because the page
* is referenced, charged, isolated, and locked: we can't race
* with (un)charging, migration, LRU putback, or anything else
* that would rely on a stable page's memory cgroup.
*
* Note that folio_memcg_lock is a memcg lock, not a page lock,
* to save space. As soon as we switch page's memory cgroup to a
* new memcg that isn't locked, the above state can change
* concurrently again. Make sure we're truly done with it.
*/
smp_mb();
css_get(&to->css);
css_put(&from->css);
folio->memcg_data = (unsigned long)to;
__folio_memcg_unlock(from);
ret = 0;
nid = folio_nid(folio);
local_irq_disable();
mem_cgroup_charge_statistics(to, nr_pages);
memcg_check_events(to, nid);
mem_cgroup_charge_statistics(from, -nr_pages);
memcg_check_events(from, nid);
local_irq_enable();
out:
return ret;
}
/**
* get_mctgt_type - get target type of moving charge
* @vma: the vma the pte to be checked belongs
* @addr: the address corresponding to the pte to be checked
* @ptent: the pte to be checked
* @target: the pointer the target page or swap ent will be stored(can be NULL)
*
* Context: Called with pte lock held.
* Return:
* * MC_TARGET_NONE - If the pte is not a target for move charge.
* * MC_TARGET_PAGE - If the page corresponding to this pte is a target for
* move charge. If @target is not NULL, the folio is stored in target->folio
* with extra refcnt taken (Caller should release it).
* * MC_TARGET_SWAP - If the swap entry corresponding to this pte is a
* target for charge migration. If @target is not NULL, the entry is
* stored in target->ent.
* * MC_TARGET_DEVICE - Like MC_TARGET_PAGE but page is device memory and
* thus not on the lru. For now such page is charged like a regular page
* would be as it is just special memory taking the place of a regular page.
* See Documentations/vm/hmm.txt and include/linux/hmm.h
*/
static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent, union mc_target *target)
{
struct page *page = NULL;
struct folio *folio;
enum mc_target_type ret = MC_TARGET_NONE;
swp_entry_t ent = { .val = 0 };
if (pte_present(ptent))
page = mc_handle_present_pte(vma, addr, ptent);
else if (pte_none_mostly(ptent))
/*
* PTE markers should be treated as a none pte here, separated
* from other swap handling below.
*/
page = mc_handle_file_pte(vma, addr, ptent);
else if (is_swap_pte(ptent))
page = mc_handle_swap_pte(vma, ptent, &ent);
if (page)
folio = page_folio(page);
if (target && page) {
if (!folio_trylock(folio)) {
folio_put(folio);
return ret;
}
/*
* page_mapped() must be stable during the move. This
* pte is locked, so if it's present, the page cannot
* become unmapped. If it isn't, we have only partial
* control over the mapped state: the page lock will
* prevent new faults against pagecache and swapcache,
* so an unmapped page cannot become mapped. However,
* if the page is already mapped elsewhere, it can
* unmap, and there is nothing we can do about it.
* Alas, skip moving the page in this case.
*/
if (!pte_present(ptent) && page_mapped(page)) {
folio_unlock(folio);
folio_put(folio);
return ret;
}
}
if (!page && !ent.val)
return ret;
if (page) {
/*
* Do only loose check w/o serialization.
* mem_cgroup_move_account() checks the page is valid or
* not under LRU exclusion.
*/
if (folio_memcg(folio) == mc.from) {
ret = MC_TARGET_PAGE;
if (folio_is_device_private(folio) ||
folio_is_device_coherent(folio))
ret = MC_TARGET_DEVICE;
if (target)
target->folio = folio;
}
if (!ret || !target) {
if (target)
folio_unlock(folio);
folio_put(folio);
}
}
/*
* There is a swap entry and a page doesn't exist or isn't charged.
* But we cannot move a tail-page in a THP.
*/
if (ent.val && !ret && (!page || !PageTransCompound(page)) &&
mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
ret = MC_TARGET_SWAP;
if (target)
target->ent = ent;
}
return ret;
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
* We don't consider PMD mapped swapping or file mapped pages because THP does
* not support them for now.
* Caller should make sure that pmd_trans_huge(pmd) is true.
*/
static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
unsigned long addr, pmd_t pmd, union mc_target *target)
{
struct page *page = NULL;
struct folio *folio;
enum mc_target_type ret = MC_TARGET_NONE;
if (unlikely(is_swap_pmd(pmd))) {
VM_BUG_ON(thp_migration_supported() &&
!is_pmd_migration_entry(pmd));
return ret;
}
page = pmd_page(pmd);
VM_BUG_ON_PAGE(!page || !PageHead(page), page);
folio = page_folio(page);
if (!(mc.flags & MOVE_ANON))
return ret;
if (folio_memcg(folio) == mc.from) {
ret = MC_TARGET_PAGE;
if (target) {
folio_get(folio);
if (!folio_trylock(folio)) {
folio_put(folio);
return MC_TARGET_NONE;
}
target->folio = folio;
}
}
return ret;
}
#else
static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
unsigned long addr, pmd_t pmd, union mc_target *target)
{
return MC_TARGET_NONE;
}
#endif
static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
pte_t *pte;
spinlock_t *ptl;
ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
/*
* Note their can not be MC_TARGET_DEVICE for now as we do not
* support transparent huge page with MEMORY_DEVICE_PRIVATE but
* this might change.
*/
if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
mc.precharge += HPAGE_PMD_NR;
spin_unlock(ptl);
return 0;
}
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
if (!pte)
return 0;
for (; addr != end; pte++, addr += PAGE_SIZE)
if (get_mctgt_type(vma, addr, ptep_get(pte), NULL))
mc.precharge++; /* increment precharge temporarily */
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
return 0;
}
static const struct mm_walk_ops precharge_walk_ops = {
.pmd_entry = mem_cgroup_count_precharge_pte_range,
.walk_lock = PGWALK_RDLOCK,
};
static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
{
unsigned long precharge;
mmap_read_lock(mm);
walk_page_range(mm, 0, ULONG_MAX, &precharge_walk_ops, NULL);
mmap_read_unlock(mm);
precharge = mc.precharge;
mc.precharge = 0;
return precharge;
}
static int mem_cgroup_precharge_mc(struct mm_struct *mm)
{
unsigned long precharge = mem_cgroup_count_precharge(mm);
VM_BUG_ON(mc.moving_task);
mc.moving_task = current;
return mem_cgroup_do_precharge(precharge);
}
/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
static void __mem_cgroup_clear_mc(void)
{
struct mem_cgroup *from = mc.from;
struct mem_cgroup *to = mc.to;
/* we must uncharge all the leftover precharges from mc.to */
if (mc.precharge) {
mem_cgroup_cancel_charge(mc.to, mc.precharge);
mc.precharge = 0;
}
/*
* we didn't uncharge from mc.from at mem_cgroup_move_account(), so
* we must uncharge here.
*/
if (mc.moved_charge) {
mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
mc.moved_charge = 0;
}
/* we must fixup refcnts and charges */
if (mc.moved_swap) {
/* uncharge swap account from the old cgroup */
if (!mem_cgroup_is_root(mc.from))
page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
mem_cgroup_id_put_many(mc.from, mc.moved_swap);
/*
* we charged both to->memory and to->memsw, so we
* should uncharge to->memory.
*/
if (!mem_cgroup_is_root(mc.to))
page_counter_uncharge(&mc.to->memory, mc.moved_swap);
mc.moved_swap = 0;
}
memcg_oom_recover(from);
memcg_oom_recover(to);
wake_up_all(&mc.waitq);
}
static void mem_cgroup_clear_mc(void)
{
struct mm_struct *mm = mc.mm;
/*
* we must clear moving_task before waking up waiters at the end of
* task migration.
*/
mc.moving_task = NULL;
__mem_cgroup_clear_mc();
spin_lock(&mc.lock);
mc.from = NULL;
mc.to = NULL;
mc.mm = NULL;
spin_unlock(&mc.lock);
mmput(mm);
}
static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */
struct mem_cgroup *from;
struct task_struct *leader, *p;
struct mm_struct *mm;
unsigned long move_flags;
int ret = 0;
/* charge immigration isn't supported on the default hierarchy */
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
return 0;
/*
* Multi-process migrations only happen on the default hierarchy
* where charge immigration is not used. Perform charge
* immigration if @tset contains a leader and whine if there are
* multiple.
*/
p = NULL;
cgroup_taskset_for_each_leader(leader, css, tset) {
WARN_ON_ONCE(p);
p = leader;
memcg = mem_cgroup_from_css(css);
}
if (!p)
return 0;
/*
* We are now committed to this value whatever it is. Changes in this
* tunable will only affect upcoming migrations, not the current one.
* So we need to save it, and keep it going.
*/
move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
if (!move_flags)
return 0;
from = mem_cgroup_from_task(p);
VM_BUG_ON(from == memcg);
mm = get_task_mm(p);
if (!mm)
return 0;
/* We move charges only when we move a owner of the mm */
if (mm->owner == p) {
VM_BUG_ON(mc.from);
VM_BUG_ON(mc.to);
VM_BUG_ON(mc.precharge);
VM_BUG_ON(mc.moved_charge);
VM_BUG_ON(mc.moved_swap);
spin_lock(&mc.lock);
mc.mm = mm;
mc.from = from;
mc.to = memcg;
mc.flags = move_flags;
spin_unlock(&mc.lock);
/* We set mc.moving_task later */
ret = mem_cgroup_precharge_mc(mm);
if (ret)
mem_cgroup_clear_mc();
} else {
mmput(mm);
}
return ret;
}
static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
{
if (mc.to)
mem_cgroup_clear_mc();
}
static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
int ret = 0;
struct vm_area_struct *vma = walk->vma;
pte_t *pte;
spinlock_t *ptl;
enum mc_target_type target_type;
union mc_target target;
struct folio *folio;
ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
if (mc.precharge < HPAGE_PMD_NR) {
spin_unlock(ptl);
return 0;
}
target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
if (target_type == MC_TARGET_PAGE) {
folio = target.folio;
if (folio_isolate_lru(folio)) {
if (!mem_cgroup_move_account(folio, true,
mc.from, mc.to)) {
mc.precharge -= HPAGE_PMD_NR;
mc.moved_charge += HPAGE_PMD_NR;
}
folio_putback_lru(folio);
}
folio_unlock(folio);
folio_put(folio);
} else if (target_type == MC_TARGET_DEVICE) {
folio = target.folio;
if (!mem_cgroup_move_account(folio, true,
mc.from, mc.to)) {
mc.precharge -= HPAGE_PMD_NR;
mc.moved_charge += HPAGE_PMD_NR;
}
folio_unlock(folio);
folio_put(folio);
}
spin_unlock(ptl);
return 0;
}
retry:
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
if (!pte)
return 0;
for (; addr != end; addr += PAGE_SIZE) {
pte_t ptent = ptep_get(pte++);
bool device = false;
swp_entry_t ent;
if (!mc.precharge)
break;
switch (get_mctgt_type(vma, addr, ptent, &target)) {
case MC_TARGET_DEVICE:
device = true;
fallthrough;
case MC_TARGET_PAGE:
folio = target.folio;
/*
* We can have a part of the split pmd here. Moving it
* can be done but it would be too convoluted so simply
* ignore such a partial THP and keep it in original
* memcg. There should be somebody mapping the head.
*/
if (folio_test_large(folio))
goto put;
if (!device && !folio_isolate_lru(folio))
goto put;
if (!mem_cgroup_move_account(folio, false,
mc.from, mc.to)) {
mc.precharge--;
/* we uncharge from mc.from later. */
mc.moved_charge++;
}
if (!device)
folio_putback_lru(folio);
put: /* get_mctgt_type() gets & locks the page */
folio_unlock(folio);
folio_put(folio);
break;
case MC_TARGET_SWAP:
ent = target.ent;
if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
mc.precharge--;
mem_cgroup_id_get_many(mc.to, 1);
/* we fixup other refcnts and charges later. */
mc.moved_swap++;
}
break;
default:
break;
}
}
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
if (addr != end) {
/*
* We have consumed all precharges we got in can_attach().
* We try charge one by one, but don't do any additional
* charges to mc.to if we have failed in charge once in attach()
* phase.
*/
ret = mem_cgroup_do_precharge(1);
if (!ret)
goto retry;
}
return ret;
}
static const struct mm_walk_ops charge_walk_ops = {
.pmd_entry = mem_cgroup_move_charge_pte_range,
.walk_lock = PGWALK_RDLOCK,
};
static void mem_cgroup_move_charge(void)
{
lru_add_drain_all();
/*
* Signal folio_memcg_lock() to take the memcg's move_lock
* while we're moving its pages to another memcg. Then wait
* for already started RCU-only updates to finish.
*/
atomic_inc(&mc.from->moving_account);
synchronize_rcu();
retry:
if (unlikely(!mmap_read_trylock(mc.mm))) {
/*
* Someone who are holding the mmap_lock might be waiting in
* waitq. So we cancel all extra charges, wake up all waiters,
* and retry. Because we cancel precharges, we might not be able
* to move enough charges, but moving charge is a best-effort
* feature anyway, so it wouldn't be a big problem.
*/
__mem_cgroup_clear_mc();
cond_resched();
goto retry;
}
/*
* When we have consumed all precharges and failed in doing
* additional charge, the page walk just aborts.
*/
walk_page_range(mc.mm, 0, ULONG_MAX, &charge_walk_ops, NULL);
mmap_read_unlock(mc.mm);
atomic_dec(&mc.from->moving_account);
}
static void mem_cgroup_move_task(void)
{
if (mc.to) {
mem_cgroup_move_charge();
mem_cgroup_clear_mc();
}
}
#else /* !CONFIG_MMU */
static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
{
return 0;
}
static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
{
}
static void mem_cgroup_move_task(void)
{
}
#endif
#ifdef CONFIG_MEMCG_KMEM
static void mem_cgroup_fork(struct task_struct *task)
{
/*
* Set the update flag to cause task->objcg to be initialized lazily
* on the first allocation. It can be done without any synchronization
* because it's always performed on the current task, so does
* current_objcg_update().
*/
task->objcg = (struct obj_cgroup *)CURRENT_OBJCG_UPDATE_FLAG;
}
static void mem_cgroup_exit(struct task_struct *task)
{
struct obj_cgroup *objcg = task->objcg;
objcg = (struct obj_cgroup *)
((unsigned long)objcg & ~CURRENT_OBJCG_UPDATE_FLAG);
if (objcg)
obj_cgroup_put(objcg);
/*
* Some kernel allocations can happen after this point,
* but let's ignore them. It can be done without any synchronization
* because it's always performed on the current task, so does
* current_objcg_update().
*/
task->objcg = NULL;
}
#endif
#ifdef CONFIG_LRU_GEN
static void mem_cgroup_lru_gen_attach(struct cgroup_taskset *tset)
{
struct task_struct *task;
struct cgroup_subsys_state *css;
/* find the first leader if there is any */
cgroup_taskset_for_each_leader(task, css, tset)
break;
if (!task)
return;
task_lock(task);
if (task->mm && READ_ONCE(task->mm->owner) == task)
lru_gen_migrate_mm(task->mm);
task_unlock(task);
}
#else
static void mem_cgroup_lru_gen_attach(struct cgroup_taskset *tset) {}
#endif /* CONFIG_LRU_GEN */
#ifdef CONFIG_MEMCG_KMEM
static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset)
{
struct task_struct *task;
struct cgroup_subsys_state *css;
cgroup_taskset_for_each(task, css, tset) {
/* atomically set the update bit */
set_bit(CURRENT_OBJCG_UPDATE_BIT, (unsigned long *)&task->objcg);
}
}
#else
static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset) {}
#endif /* CONFIG_MEMCG_KMEM */
#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM)
static void mem_cgroup_attach(struct cgroup_taskset *tset)
{
mem_cgroup_lru_gen_attach(tset);
mem_cgroup_kmem_attach(tset);
}
#endif
static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value)
{
if (value == PAGE_COUNTER_MAX)
seq_puts(m, "max\n");
else
seq_printf(m, "%llu\n", (u64)value * PAGE_SIZE);
return 0;
}
static u64 memory_current_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
return (u64)page_counter_read(&memcg->memory) * PAGE_SIZE;
}
static u64 memory_peak_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
return (u64)memcg->memory.watermark * PAGE_SIZE;
}
static int memory_min_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->memory.min));
}
static ssize_t memory_min_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long min;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &min);
if (err)
return err;
page_counter_set_min(&memcg->memory, min);
return nbytes;
}
static int memory_low_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->memory.low));
}
static ssize_t memory_low_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long low;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &low);
if (err)
return err;
page_counter_set_low(&memcg->memory, low);
return nbytes;
}
static int memory_high_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->memory.high));
}
static ssize_t memory_high_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned int nr_retries = MAX_RECLAIM_RETRIES;
bool drained = false;
unsigned long high;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &high);
if (err)
return err;
page_counter_set_high(&memcg->memory, high);
for (;;) {
unsigned long nr_pages = page_counter_read(&memcg->memory);
unsigned long reclaimed;
if (nr_pages <= high)
break;
if (signal_pending(current))
break;
if (!drained) {
drain_all_stock(memcg);
drained = true;
continue;
}
reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP);
if (!reclaimed && !nr_retries--)
break;
}
memcg_wb_domain_size_changed(memcg);
return nbytes;
}
static int memory_max_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->memory.max));
}
static ssize_t memory_max_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned int nr_reclaims = MAX_RECLAIM_RETRIES;
bool drained = false;
unsigned long max;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &max);
if (err)
return err;
xchg(&memcg->memory.max, max);
for (;;) {
unsigned long nr_pages = page_counter_read(&memcg->memory);
if (nr_pages <= max)
break;
if (signal_pending(current))
break;
if (!drained) {
drain_all_stock(memcg);
drained = true;
continue;
}
if (nr_reclaims) {
if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max,
GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP))
nr_reclaims--;
continue;
}
memcg_memory_event(memcg, MEMCG_OOM);
if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0))
break;
}
memcg_wb_domain_size_changed(memcg);
return nbytes;
}
/*
* Note: don't forget to update the 'samples/cgroup/memcg_event_listener'
* if any new events become available.
*/
static void __memory_events_show(struct seq_file *m, atomic_long_t *events)
{
seq_printf(m, "low %lu\n", atomic_long_read(&events[MEMCG_LOW]));
seq_printf(m, "high %lu\n", atomic_long_read(&events[MEMCG_HIGH]));
seq_printf(m, "max %lu\n", atomic_long_read(&events[MEMCG_MAX]));
seq_printf(m, "oom %lu\n", atomic_long_read(&events[MEMCG_OOM]));
seq_printf(m, "oom_kill %lu\n",
atomic_long_read(&events[MEMCG_OOM_KILL]));
seq_printf(m, "oom_group_kill %lu\n",
atomic_long_read(&events[MEMCG_OOM_GROUP_KILL]));
}
static int memory_events_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
__memory_events_show(m, memcg->memory_events);
return 0;
}
static int memory_events_local_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
__memory_events_show(m, memcg->memory_events_local);
return 0;
}
static int memory_stat_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
char *buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
struct seq_buf s;
if (!buf)
return -ENOMEM;
seq_buf_init(&s, buf, PAGE_SIZE);
memory_stat_format(memcg, &s);
seq_puts(m, buf);
kfree(buf);
return 0;
}
#ifdef CONFIG_NUMA
static inline unsigned long lruvec_page_state_output(struct lruvec *lruvec,
int item)
{
return lruvec_page_state(lruvec, item) *
memcg_page_state_output_unit(item);
}
static int memory_numa_stat_show(struct seq_file *m, void *v)
{
int i;
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
mem_cgroup_flush_stats(memcg);
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
int nid;
if (memory_stats[i].idx >= NR_VM_NODE_STAT_ITEMS)
continue;
seq_printf(m, "%s", memory_stats[i].name);
for_each_node_state(nid, N_MEMORY) {
u64 size;
struct lruvec *lruvec;
lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
size = lruvec_page_state_output(lruvec,
memory_stats[i].idx);
seq_printf(m, " N%d=%llu", nid, size);
}
seq_putc(m, '\n');
}
return 0;
}
#endif
static int memory_oom_group_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
seq_printf(m, "%d\n", READ_ONCE(memcg->oom_group));
return 0;
}
static ssize_t memory_oom_group_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
int ret, oom_group;
buf = strstrip(buf);
if (!buf)
return -EINVAL;
ret = kstrtoint(buf, 0, &oom_group);
if (ret)
return ret;
if (oom_group != 0 && oom_group != 1)
return -EINVAL;
WRITE_ONCE(memcg->oom_group, oom_group);
return nbytes;
}
static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned int nr_retries = MAX_RECLAIM_RETRIES;
unsigned long nr_to_reclaim, nr_reclaimed = 0;
unsigned int reclaim_options;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "", &nr_to_reclaim);
if (err)
return err;
reclaim_options = MEMCG_RECLAIM_MAY_SWAP | MEMCG_RECLAIM_PROACTIVE;
while (nr_reclaimed < nr_to_reclaim) {
/* Will converge on zero, but reclaim enforces a minimum */
unsigned long batch_size = (nr_to_reclaim - nr_reclaimed) / 4;
unsigned long reclaimed;
if (signal_pending(current))
return -EINTR;
/*
* This is the final attempt, drain percpu lru caches in the
* hope of introducing more evictable pages for
* try_to_free_mem_cgroup_pages().
*/
if (!nr_retries)
lru_add_drain_all();
reclaimed = try_to_free_mem_cgroup_pages(memcg,
batch_size, GFP_KERNEL, reclaim_options);
if (!reclaimed && !nr_retries--)
return -EAGAIN;
nr_reclaimed += reclaimed;
}
return nbytes;
}
static struct cftype memory_files[] = {
{
.name = "current",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = memory_current_read,
},
{
.name = "peak",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = memory_peak_read,
},
{
.name = "min",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = memory_min_show,
.write = memory_min_write,
},
{
.name = "low",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = memory_low_show,
.write = memory_low_write,
},
{
.name = "high",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = memory_high_show,
.write = memory_high_write,
},
{
.name = "max",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = memory_max_show,
.write = memory_max_write,
},
{
.name = "events",
.flags = CFTYPE_NOT_ON_ROOT,
.file_offset = offsetof(struct mem_cgroup, events_file),
.seq_show = memory_events_show,
},
{
.name = "events.local",
.flags = CFTYPE_NOT_ON_ROOT,
.file_offset = offsetof(struct mem_cgroup, events_local_file),
.seq_show = memory_events_local_show,
},
{
.name = "stat",
.seq_show = memory_stat_show,
},
#ifdef CONFIG_NUMA
{
.name = "numa_stat",
.seq_show = memory_numa_stat_show,
},
#endif
{
.name = "oom.group",
.flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
.seq_show = memory_oom_group_show,
.write = memory_oom_group_write,
},
{
.name = "reclaim",
.flags = CFTYPE_NS_DELEGATABLE,
.write = memory_reclaim,
},
{ } /* terminate */
};
struct cgroup_subsys memory_cgrp_subsys = {
.css_alloc = mem_cgroup_css_alloc,
.css_online = mem_cgroup_css_online,
.css_offline = mem_cgroup_css_offline,
.css_released = mem_cgroup_css_released,
.css_free = mem_cgroup_css_free,
.css_reset = mem_cgroup_css_reset,
.css_rstat_flush = mem_cgroup_css_rstat_flush,
.can_attach = mem_cgroup_can_attach,
#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM)
.attach = mem_cgroup_attach,
#endif
.cancel_attach = mem_cgroup_cancel_attach,
.post_attach = mem_cgroup_move_task,
#ifdef CONFIG_MEMCG_KMEM
.fork = mem_cgroup_fork,
.exit = mem_cgroup_exit,
#endif
.dfl_cftypes = memory_files,
.legacy_cftypes = mem_cgroup_legacy_files,
.early_init = 0,
};
/*
* This function calculates an individual cgroup's effective
* protection which is derived from its own memory.min/low, its
* parent's and siblings' settings, as well as the actual memory
* distribution in the tree.
*
* The following rules apply to the effective protection values:
*
* 1. At the first level of reclaim, effective protection is equal to
* the declared protection in memory.min and memory.low.
*
* 2. To enable safe delegation of the protection configuration, at
* subsequent levels the effective protection is capped to the
* parent's effective protection.
*
* 3. To make complex and dynamic subtrees easier to configure, the
* user is allowed to overcommit the declared protection at a given
* level. If that is the case, the parent's effective protection is
* distributed to the children in proportion to how much protection
* they have declared and how much of it they are utilizing.
*
* This makes distribution proportional, but also work-conserving:
* if one cgroup claims much more protection than it uses memory,
* the unused remainder is available to its siblings.
*
* 4. Conversely, when the declared protection is undercommitted at a
* given level, the distribution of the larger parental protection
* budget is NOT proportional. A cgroup's protection from a sibling
* is capped to its own memory.min/low setting.
*
* 5. However, to allow protecting recursive subtrees from each other
* without having to declare each individual cgroup's fixed share
* of the ancestor's claim to protection, any unutilized -
* "floating" - protection from up the tree is distributed in
* proportion to each cgroup's *usage*. This makes the protection
* neutral wrt sibling cgroups and lets them compete freely over
* the shared parental protection budget, but it protects the
* subtree as a whole from neighboring subtrees.
*
* Note that 4. and 5. are not in conflict: 4. is about protecting
* against immediate siblings whereas 5. is about protecting against
* neighboring subtrees.
*/
static unsigned long effective_protection(unsigned long usage,
unsigned long parent_usage,
unsigned long setting,
unsigned long parent_effective,
unsigned long siblings_protected)
{
unsigned long protected;
unsigned long ep;
protected = min(usage, setting);
/*
* If all cgroups at this level combined claim and use more
* protection than what the parent affords them, distribute
* shares in proportion to utilization.
*
* We are using actual utilization rather than the statically
* claimed protection in order to be work-conserving: claimed
* but unused protection is available to siblings that would
* otherwise get a smaller chunk than what they claimed.
*/
if (siblings_protected > parent_effective)
return protected * parent_effective / siblings_protected;
/*
* Ok, utilized protection of all children is within what the
* parent affords them, so we know whatever this child claims
* and utilizes is effectively protected.
*
* If there is unprotected usage beyond this value, reclaim
* will apply pressure in proportion to that amount.
*
* If there is unutilized protection, the cgroup will be fully
* shielded from reclaim, but we do return a smaller value for
* protection than what the group could enjoy in theory. This
* is okay. With the overcommit distribution above, effective
* protection is always dependent on how memory is actually
* consumed among the siblings anyway.
*/
ep = protected;
/*
* If the children aren't claiming (all of) the protection
* afforded to them by the parent, distribute the remainder in
* proportion to the (unprotected) memory of each cgroup. That
* way, cgroups that aren't explicitly prioritized wrt each
* other compete freely over the allowance, but they are
* collectively protected from neighboring trees.
*
* We're using unprotected memory for the weight so that if
* some cgroups DO claim explicit protection, we don't protect
* the same bytes twice.
*
* Check both usage and parent_usage against the respective
* protected values. One should imply the other, but they
* aren't read atomically - make sure the division is sane.
*/
if (!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT))
return ep;
if (parent_effective > siblings_protected &&
parent_usage > siblings_protected &&
usage > protected) {
unsigned long unclaimed;
unclaimed = parent_effective - siblings_protected;
unclaimed *= usage - protected;
unclaimed /= parent_usage - siblings_protected;
ep += unclaimed;
}
return ep;
}
/**
* mem_cgroup_calculate_protection - check if memory consumption is in the normal range
* @root: the top ancestor of the sub-tree being checked
* @memcg: the memory cgroup to check
*
* WARNING: This function is not stateless! It can only be used as part
* of a top-down tree iteration, not for isolated queries.
*/
void mem_cgroup_calculate_protection(struct mem_cgroup *root,
struct mem_cgroup *memcg)
{
unsigned long usage, parent_usage;
struct mem_cgroup *parent;
if (mem_cgroup_disabled())
return;
if (!root)
root = root_mem_cgroup;
/*
* Effective values of the reclaim targets are ignored so they
* can be stale. Have a look at mem_cgroup_protection for more
* details.
* TODO: calculation should be more robust so that we do not need
* that special casing.
*/
if (memcg == root)
return;
usage = page_counter_read(&memcg->memory);
if (!usage)
return;
parent = parent_mem_cgroup(memcg);
if (parent == root) {
memcg->memory.emin = READ_ONCE(memcg->memory.min);
memcg->memory.elow = READ_ONCE(memcg->memory.low);
return;
}
parent_usage = page_counter_read(&parent->memory);
WRITE_ONCE(memcg->memory.emin, effective_protection(usage, parent_usage,
READ_ONCE(memcg->memory.min),
READ_ONCE(parent->memory.emin),
atomic_long_read(&parent->memory.children_min_usage)));
WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage,
READ_ONCE(memcg->memory.low),
READ_ONCE(parent->memory.elow),
atomic_long_read(&parent->memory.children_low_usage)));
}
static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg,
gfp_t gfp)
{
int ret;
ret = try_charge(memcg, gfp, folio_nr_pages(folio));
if (ret)
goto out;
mem_cgroup_commit_charge(folio, memcg);
out:
return ret;
}
int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp)
{
struct mem_cgroup *memcg;
int ret;
memcg = get_mem_cgroup_from_mm(mm);
ret = charge_memcg(folio, memcg, gfp);
css_put(&memcg->css);
return ret;
}
/**
* mem_cgroup_hugetlb_try_charge - try to charge the memcg for a hugetlb folio
* @memcg: memcg to charge.
* @gfp: reclaim mode.
* @nr_pages: number of pages to charge.
*
* This function is called when allocating a huge page folio to determine if
* the memcg has the capacity for it. It does not commit the charge yet,
* as the hugetlb folio itself has not been obtained from the hugetlb pool.
*
* Once we have obtained the hugetlb folio, we can call
* mem_cgroup_commit_charge() to commit the charge. If we fail to obtain the
* folio, we should instead call mem_cgroup_cancel_charge() to undo the effect
* of try_charge().
*
* Returns 0 on success. Otherwise, an error code is returned.
*/
int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp,
long nr_pages)
{
/*
* If hugetlb memcg charging is not enabled, do not fail hugetlb allocation,
* but do not attempt to commit charge later (or cancel on error) either.
*/
if (mem_cgroup_disabled() || !memcg ||
!cgroup_subsys_on_dfl(memory_cgrp_subsys) ||
!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING))
return -EOPNOTSUPP;
if (try_charge(memcg, gfp, nr_pages))
return -ENOMEM;
return 0;
}
/**
* mem_cgroup_swapin_charge_folio - Charge a newly allocated folio for swapin.
* @folio: folio to charge.
* @mm: mm context of the victim
* @gfp: reclaim mode
* @entry: swap entry for which the folio is allocated
*
* This function charges a folio allocated for swapin. Please call this before
* adding the folio to the swapcache.
*
* Returns 0 on success. Otherwise, an error code is returned.
*/
int mem_cgroup_swapin_charge_folio(struct folio *folio, struct mm_struct *mm,
gfp_t gfp, swp_entry_t entry)
{
struct mem_cgroup *memcg;
unsigned short id;
int ret;
if (mem_cgroup_disabled())
return 0;
id = lookup_swap_cgroup_id(entry);
rcu_read_lock();
memcg = mem_cgroup_from_id(id);
if (!memcg || !css_tryget_online(&memcg->css))
memcg = get_mem_cgroup_from_mm(mm);
rcu_read_unlock();
ret = charge_memcg(folio, memcg, gfp);
css_put(&memcg->css);
return ret;
}
/*
* mem_cgroup_swapin_uncharge_swap - uncharge swap slot
* @entry: swap entry for which the page is charged
*
* Call this function after successfully adding the charged page to swapcache.
*
* Note: This function assumes the page for which swap slot is being uncharged
* is order 0 page.
*/
void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
{
/*
* Cgroup1's unified memory+swap counter has been charged with the
* new swapcache page, finish the transfer by uncharging the swap
* slot. The swap slot would also get uncharged when it dies, but
* it can stick around indefinitely and we'd count the page twice
* the entire time.
*
* Cgroup2 has separate resource counters for memory and swap,
* so this is a non-issue here. Memory and swap charge lifetimes
* correspond 1:1 to page and swap slot lifetimes: we charge the
* page to memory here, and uncharge swap when the slot is freed.
*/
if (!mem_cgroup_disabled() && do_memsw_account()) {
/*
* The swap entry might not get freed for a long time,
* let's not wait for it. The page already received a
* memory+swap charge, drop the swap entry duplicate.
*/
mem_cgroup_uncharge_swap(entry, 1);
}
}
struct uncharge_gather {
struct mem_cgroup *memcg;
unsigned long nr_memory;
unsigned long pgpgout;
unsigned long nr_kmem;
int nid;
};
static inline void uncharge_gather_clear(struct uncharge_gather *ug)
{
memset(ug, 0, sizeof(*ug));
}
static void uncharge_batch(const struct uncharge_gather *ug)
{
unsigned long flags;
if (ug->nr_memory) {
page_counter_uncharge(&ug->memcg->memory, ug->nr_memory);
if (do_memsw_account())
page_counter_uncharge(&ug->memcg->memsw, ug->nr_memory);
if (ug->nr_kmem)
memcg_account_kmem(ug->memcg, -ug->nr_kmem);
memcg_oom_recover(ug->memcg);
}
local_irq_save(flags);
__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory);
memcg_check_events(ug->memcg, ug->nid);
local_irq_restore(flags);
/* drop reference from uncharge_folio */
css_put(&ug->memcg->css);
}
static void uncharge_folio(struct folio *folio, struct uncharge_gather *ug)
{
long nr_pages;
struct mem_cgroup *memcg;
struct obj_cgroup *objcg;
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
/*
* Nobody should be changing or seriously looking at
* folio memcg or objcg at this point, we have fully
* exclusive access to the folio.
*/
if (folio_memcg_kmem(folio)) {
objcg = __folio_objcg(folio);
/*
* This get matches the put at the end of the function and
* kmem pages do not hold memcg references anymore.
*/
memcg = get_mem_cgroup_from_objcg(objcg);
} else {
memcg = __folio_memcg(folio);
}
if (!memcg)
return;
if (ug->memcg != memcg) {
if (ug->memcg) {
uncharge_batch(ug);
uncharge_gather_clear(ug);
}
ug->memcg = memcg;
ug->nid = folio_nid(folio);
/* pairs with css_put in uncharge_batch */
css_get(&memcg->css);
}
nr_pages = folio_nr_pages(folio);
if (folio_memcg_kmem(folio)) {
ug->nr_memory += nr_pages;
ug->nr_kmem += nr_pages;
folio->memcg_data = 0;
obj_cgroup_put(objcg);
} else {
/* LRU pages aren't accounted at the root level */
if (!mem_cgroup_is_root(memcg))
ug->nr_memory += nr_pages;
ug->pgpgout++;
folio->memcg_data = 0;
}
css_put(&memcg->css);
}
void __mem_cgroup_uncharge(struct folio *folio)
{
struct uncharge_gather ug;
/* Don't touch folio->lru of any random page, pre-check: */
if (!folio_memcg(folio))
return;
uncharge_gather_clear(&ug);
uncharge_folio(folio, &ug);
uncharge_batch(&ug);
}
void __mem_cgroup_uncharge_folios(struct folio_batch *folios)
{
struct uncharge_gather ug;
unsigned int i;
uncharge_gather_clear(&ug);
for (i = 0; i < folios->nr; i++)
uncharge_folio(folios->folios[i], &ug);
if (ug.memcg)
uncharge_batch(&ug);
}
/**
* mem_cgroup_replace_folio - Charge a folio's replacement.
* @old: Currently circulating folio.
* @new: Replacement folio.
*
* Charge @new as a replacement folio for @old. @old will
* be uncharged upon free. This is only used by the page cache
* (in replace_page_cache_folio()).
*
* Both folios must be locked, @new->mapping must be set up.
*/
void mem_cgroup_replace_folio(struct folio *old, struct folio *new)
{
struct mem_cgroup *memcg;
long nr_pages = folio_nr_pages(new);
unsigned long flags;
VM_BUG_ON_FOLIO(!folio_test_locked(old), old);
VM_BUG_ON_FOLIO(!folio_test_locked(new), new);
VM_BUG_ON_FOLIO(folio_test_anon(old) != folio_test_anon(new), new);
VM_BUG_ON_FOLIO(folio_nr_pages(old) != nr_pages, new);
if (mem_cgroup_disabled())
return;
/* Page cache replacement: new folio already charged? */
if (folio_memcg(new))
return;
memcg = folio_memcg(old);
VM_WARN_ON_ONCE_FOLIO(!memcg, old);
if (!memcg)
return;
/* Force-charge the new page. The old one will be freed soon */
if (!mem_cgroup_is_root(memcg)) {
page_counter_charge(&memcg->memory, nr_pages);
if (do_memsw_account())
page_counter_charge(&memcg->memsw, nr_pages);
}
css_get(&memcg->css);
commit_charge(new, memcg);
local_irq_save(flags);
mem_cgroup_charge_statistics(memcg, nr_pages);
memcg_check_events(memcg, folio_nid(new));
local_irq_restore(flags);
}
/**
* mem_cgroup_migrate - Transfer the memcg data from the old to the new folio.
* @old: Currently circulating folio.
* @new: Replacement folio.
*
* Transfer the memcg data from the old folio to the new folio for migration.
* The old folio's data info will be cleared. Note that the memory counters
* will remain unchanged throughout the process.
*
* Both folios must be locked, @new->mapping must be set up.
*/
void mem_cgroup_migrate(struct folio *old, struct folio *new)
{
struct mem_cgroup *memcg;
VM_BUG_ON_FOLIO(!folio_test_locked(old), old);
VM_BUG_ON_FOLIO(!folio_test_locked(new), new);
VM_BUG_ON_FOLIO(folio_test_anon(old) != folio_test_anon(new), new);
VM_BUG_ON_FOLIO(folio_nr_pages(old) != folio_nr_pages(new), new);
if (mem_cgroup_disabled())
return;
memcg = folio_memcg(old);
/*
* Note that it is normal to see !memcg for a hugetlb folio.
* For e.g, itt could have been allocated when memory_hugetlb_accounting
* was not selected.
*/
VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(old) && !memcg, old);
if (!memcg)
return;
/* Transfer the charge and the css ref */
commit_charge(new, memcg);
/*
* If the old folio is a large folio and is in the split queue, it needs
* to be removed from the split queue now, in case getting an incorrect
* split queue in destroy_large_folio() after the memcg of the old folio
* is cleared.
*
* In addition, the old folio is about to be freed after migration, so
* removing from the split queue a bit earlier seems reasonable.
*/
if (folio_test_large(old) && folio_test_large_rmappable(old))
folio_undo_large_rmappable(old);
old->memcg_data = 0;
}
DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
EXPORT_SYMBOL(memcg_sockets_enabled_key);
void mem_cgroup_sk_alloc(struct sock *sk)
{
struct mem_cgroup *memcg;
if (!mem_cgroup_sockets_enabled)
return;
/* Do not associate the sock with unrelated interrupted task's memcg. */
if (!in_task())
return;
rcu_read_lock();
memcg = mem_cgroup_from_task(current);
if (mem_cgroup_is_root(memcg))
goto out;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcpmem_active)
goto out;
if (css_tryget(&memcg->css))
sk->sk_memcg = memcg;
out:
rcu_read_unlock();
}
void mem_cgroup_sk_free(struct sock *sk)
{
if (sk->sk_memcg)
css_put(&sk->sk_memcg->css);
}
/**
* mem_cgroup_charge_skmem - charge socket memory
* @memcg: memcg to charge
* @nr_pages: number of pages to charge
* @gfp_mask: reclaim mode
*
* Charges @nr_pages to @memcg. Returns %true if the charge fit within
* @memcg's configured limit, %false if it doesn't.
*/
bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
gfp_t gfp_mask)
{
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
struct page_counter *fail;
if (page_counter_try_charge(&memcg->tcpmem, nr_pages, &fail)) {
memcg->tcpmem_pressure = 0;
return true;
}
memcg->tcpmem_pressure = 1;
if (gfp_mask & __GFP_NOFAIL) {
page_counter_charge(&memcg->tcpmem, nr_pages);
return true;
}
return false;
}
if (try_charge(memcg, gfp_mask, nr_pages) == 0) {
mod_memcg_state(memcg, MEMCG_SOCK, nr_pages);
return true;
}
return false;
}
/**
* mem_cgroup_uncharge_skmem - uncharge socket memory
* @memcg: memcg to uncharge
* @nr_pages: number of pages to uncharge
*/
void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
{
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
page_counter_uncharge(&memcg->tcpmem, nr_pages);
return;
}
mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages);
refill_stock(memcg, nr_pages);
}
static int __init cgroup_memory(char *s)
{
char *token;
while ((token = strsep(&s, ",")) != NULL) {
if (!*token)
continue;
if (!strcmp(token, "nosocket"))
cgroup_memory_nosocket = true;
if (!strcmp(token, "nokmem"))
cgroup_memory_nokmem = true;
if (!strcmp(token, "nobpf"))
cgroup_memory_nobpf = true;
}
return 1;
}
__setup("cgroup.memory=", cgroup_memory);
/*
* subsys_initcall() for memory controller.
*
* Some parts like memcg_hotplug_cpu_dead() have to be initialized from this
* context because of lock dependencies (cgroup_lock -> cpu hotplug) but
* basically everything that doesn't depend on a specific mem_cgroup structure
* should be initialized from here.
*/
static int __init mem_cgroup_init(void)
{
int cpu, node;
/*
* Currently s32 type (can refer to struct batched_lruvec_stat) is
* used for per-memcg-per-cpu caching of per-node statistics. In order
* to work fine, we should make sure that the overfill threshold can't
* exceed S32_MAX / PAGE_SIZE.
*/
BUILD_BUG_ON(MEMCG_CHARGE_BATCH > S32_MAX / PAGE_SIZE);
cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL,
memcg_hotplug_cpu_dead);
for_each_possible_cpu(cpu)
INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
drain_local_stock);
for_each_node(node) {
struct mem_cgroup_tree_per_node *rtpn;
rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, node);
rtpn->rb_root = RB_ROOT;
rtpn->rb_rightmost = NULL;
spin_lock_init(&rtpn->lock);
soft_limit_tree.rb_tree_per_node[node] = rtpn;
}
return 0;
}
subsys_initcall(mem_cgroup_init);
#ifdef CONFIG_SWAP
static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
{
while (!refcount_inc_not_zero(&memcg->id.ref)) {
/*
* The root cgroup cannot be destroyed, so it's refcount must
* always be >= 1.
*/
if (WARN_ON_ONCE(mem_cgroup_is_root(memcg))) {
VM_BUG_ON(1);
break;
}
memcg = parent_mem_cgroup(memcg);
if (!memcg)
memcg = root_mem_cgroup;
}
return memcg;
}
/**
* mem_cgroup_swapout - transfer a memsw charge to swap
* @folio: folio whose memsw charge to transfer
* @entry: swap entry to move the charge to
*
* Transfer the memsw charge of @folio to @entry.
*/
void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
{
struct mem_cgroup *memcg, *swap_memcg;
unsigned int nr_entries;
unsigned short oldid;
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
if (mem_cgroup_disabled())
return;
if (!do_memsw_account())
return;
memcg = folio_memcg(folio);
VM_WARN_ON_ONCE_FOLIO(!memcg, folio);
if (!memcg)
return;
/*
* In case the memcg owning these pages has been offlined and doesn't
* have an ID allocated to it anymore, charge the closest online
* ancestor for the swap instead and transfer the memory+swap charge.
*/
swap_memcg = mem_cgroup_id_get_online(memcg);
nr_entries = folio_nr_pages(folio);
/* Get references for the tail pages, too */
if (nr_entries > 1)
mem_cgroup_id_get_many(swap_memcg, nr_entries - 1);
oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg),
nr_entries);
VM_BUG_ON_FOLIO(oldid, folio);
mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries);
folio->memcg_data = 0;
if (!mem_cgroup_is_root(memcg))
page_counter_uncharge(&memcg->memory, nr_entries);
if (memcg != swap_memcg) {
if (!mem_cgroup_is_root(swap_memcg))
page_counter_charge(&swap_memcg->memsw, nr_entries);
page_counter_uncharge(&memcg->memsw, nr_entries);
}
/*
* Interrupts should be disabled here because the caller holds the
* i_pages lock which is taken with interrupts-off. It is
* important here to have the interrupts disabled because it is the
* only synchronisation we have for updating the per-CPU variables.
*/
memcg_stats_lock();
mem_cgroup_charge_statistics(memcg, -nr_entries);
memcg_stats_unlock();
memcg_check_events(memcg, folio_nid(folio));
css_put(&memcg->css);
}
/**
* __mem_cgroup_try_charge_swap - try charging swap space for a folio
* @folio: folio being added to swap
* @entry: swap entry to charge
*
* Try to charge @folio's memcg for the swap space at @entry.
*
* Returns 0 on success, -ENOMEM on failure.
*/
int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry)
{
unsigned int nr_pages = folio_nr_pages(folio);
struct page_counter *counter;
struct mem_cgroup *memcg;
unsigned short oldid;
if (do_memsw_account())
return 0;
memcg = folio_memcg(folio);
VM_WARN_ON_ONCE_FOLIO(!memcg, folio);
if (!memcg)
return 0;
if (!entry.val) {
memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
return 0;
}
memcg = mem_cgroup_id_get_online(memcg);
if (!mem_cgroup_is_root(memcg) &&
!page_counter_try_charge(&memcg->swap, nr_pages, &counter)) {
memcg_memory_event(memcg, MEMCG_SWAP_MAX);
memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
mem_cgroup_id_put(memcg);
return -ENOMEM;
}
/* Get references for the tail pages, too */
if (nr_pages > 1)
mem_cgroup_id_get_many(memcg, nr_pages - 1);
oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_pages);
VM_BUG_ON_FOLIO(oldid, folio);
mod_memcg_state(memcg, MEMCG_SWAP, nr_pages);
return 0;
}
/**
* __mem_cgroup_uncharge_swap - uncharge swap space
* @entry: swap entry to uncharge
* @nr_pages: the amount of swap space to uncharge
*/
void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
{
struct mem_cgroup *memcg;
unsigned short id;
id = swap_cgroup_record(entry, 0, nr_pages);
rcu_read_lock();
memcg = mem_cgroup_from_id(id);
if (memcg) {
if (!mem_cgroup_is_root(memcg)) {
if (do_memsw_account())
page_counter_uncharge(&memcg->memsw, nr_pages);
else
page_counter_uncharge(&memcg->swap, nr_pages);
}
mod_memcg_state(memcg, MEMCG_SWAP, -nr_pages);
mem_cgroup_id_put_many(memcg, nr_pages);
}
rcu_read_unlock();
}
long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
{
long nr_swap_pages = get_nr_swap_pages();
if (mem_cgroup_disabled() || do_memsw_account())
return nr_swap_pages;
for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg))
nr_swap_pages = min_t(long, nr_swap_pages,
READ_ONCE(memcg->swap.max) -
page_counter_read(&memcg->swap));
return nr_swap_pages;
}
bool mem_cgroup_swap_full(struct folio *folio)
{
struct mem_cgroup *memcg;
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
if (vm_swap_full())
return true;
if (do_memsw_account())
return false;
memcg = folio_memcg(folio);
if (!memcg)
return false;
for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) {
unsigned long usage = page_counter_read(&memcg->swap);
if (usage * 2 >= READ_ONCE(memcg->swap.high) ||
usage * 2 >= READ_ONCE(memcg->swap.max))
return true;
}
return false;
}
static int __init setup_swap_account(char *s)
{
bool res;
if (!kstrtobool(s, &res) && !res)
pr_warn_once("The swapaccount=0 commandline option is deprecated "
"in favor of configuring swap control via cgroupfs. "
"Please report your usecase to linux-mm@kvack.org if you "
"depend on this functionality.\n");
return 1;
}
__setup("swapaccount=", setup_swap_account);
static u64 swap_current_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
return (u64)page_counter_read(&memcg->swap) * PAGE_SIZE;
}
static u64 swap_peak_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
return (u64)memcg->swap.watermark * PAGE_SIZE;
}
static int swap_high_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->swap.high));
}
static ssize_t swap_high_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long high;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &high);
if (err)
return err;
page_counter_set_high(&memcg->swap, high);
return nbytes;
}
static int swap_max_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->swap.max));
}
static ssize_t swap_max_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long max;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &max);
if (err)
return err;
xchg(&memcg->swap.max, max);
return nbytes;
}
static int swap_events_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
seq_printf(m, "high %lu\n",
atomic_long_read(&memcg->memory_events[MEMCG_SWAP_HIGH]));
seq_printf(m, "max %lu\n",
atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX]));
seq_printf(m, "fail %lu\n",
atomic_long_read(&memcg->memory_events[MEMCG_SWAP_FAIL]));
return 0;
}
static struct cftype swap_files[] = {
{
.name = "swap.current",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = swap_current_read,
},
{
.name = "swap.high",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = swap_high_show,
.write = swap_high_write,
},
{
.name = "swap.max",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = swap_max_show,
.write = swap_max_write,
},
{
.name = "swap.peak",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = swap_peak_read,
},
{
.name = "swap.events",
.flags = CFTYPE_NOT_ON_ROOT,
.file_offset = offsetof(struct mem_cgroup, swap_events_file),
.seq_show = swap_events_show,
},
{ } /* terminate */
};
static struct cftype memsw_files[] = {
{
.name = "memsw.usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
.write = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.failcnt",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{ }, /* terminate */
};
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
/**
* obj_cgroup_may_zswap - check if this cgroup can zswap
* @objcg: the object cgroup
*
* Check if the hierarchical zswap limit has been reached.
*
* This doesn't check for specific headroom, and it is not atomic
* either. But with zswap, the size of the allocation is only known
* once compression has occurred, and this optimistic pre-check avoids
* spending cycles on compression when there is already no room left
* or zswap is disabled altogether somewhere in the hierarchy.
*/
bool obj_cgroup_may_zswap(struct obj_cgroup *objcg)
{
struct mem_cgroup *memcg, *original_memcg;
bool ret = true;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
return true;
original_memcg = get_mem_cgroup_from_objcg(objcg);
for (memcg = original_memcg; !mem_cgroup_is_root(memcg);
memcg = parent_mem_cgroup(memcg)) {
unsigned long max = READ_ONCE(memcg->zswap_max);
unsigned long pages;
if (max == PAGE_COUNTER_MAX)
continue;
if (max == 0) {
ret = false;
break;
}
/*
* mem_cgroup_flush_stats() ignores small changes. Use
* do_flush_stats() directly to get accurate stats for charging.
*/
do_flush_stats(memcg);
pages = memcg_page_state(memcg, MEMCG_ZSWAP_B) / PAGE_SIZE;
if (pages < max)
continue;
ret = false;
break;
}
mem_cgroup_put(original_memcg);
return ret;
}
/**
* obj_cgroup_charge_zswap - charge compression backend memory
* @objcg: the object cgroup
* @size: size of compressed object
*
* This forces the charge after obj_cgroup_may_zswap() allowed
* compression and storage in zwap for this cgroup to go ahead.
*/
void obj_cgroup_charge_zswap(struct obj_cgroup *objcg, size_t size)
{
struct mem_cgroup *memcg;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
return;
VM_WARN_ON_ONCE(!(current->flags & PF_MEMALLOC));
/* PF_MEMALLOC context, charging must succeed */
if (obj_cgroup_charge(objcg, GFP_KERNEL, size))
VM_WARN_ON_ONCE(1);
rcu_read_lock();
memcg = obj_cgroup_memcg(objcg);
mod_memcg_state(memcg, MEMCG_ZSWAP_B, size);
mod_memcg_state(memcg, MEMCG_ZSWAPPED, 1);
rcu_read_unlock();
}
/**
* obj_cgroup_uncharge_zswap - uncharge compression backend memory
* @objcg: the object cgroup
* @size: size of compressed object
*
* Uncharges zswap memory on page in.
*/
void obj_cgroup_uncharge_zswap(struct obj_cgroup *objcg, size_t size)
{
struct mem_cgroup *memcg;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
return;
obj_cgroup_uncharge(objcg, size);
rcu_read_lock();
memcg = obj_cgroup_memcg(objcg);
mod_memcg_state(memcg, MEMCG_ZSWAP_B, -size);
mod_memcg_state(memcg, MEMCG_ZSWAPPED, -1);
rcu_read_unlock();
}
bool mem_cgroup_zswap_writeback_enabled(struct mem_cgroup *memcg)
{
/* if zswap is disabled, do not block pages going to the swapping device */
return !is_zswap_enabled() || !memcg || READ_ONCE(memcg->zswap_writeback);
}
static u64 zswap_current_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
mem_cgroup_flush_stats(memcg);
return memcg_page_state(memcg, MEMCG_ZSWAP_B);
}
static int zswap_max_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
READ_ONCE(mem_cgroup_from_seq(m)->zswap_max));
}
static ssize_t zswap_max_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long max;
int err;
buf = strstrip(buf);
err = page_counter_memparse(buf, "max", &max);
if (err)
return err;
xchg(&memcg->zswap_max, max);
return nbytes;
}
static int zswap_writeback_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
seq_printf(m, "%d\n", READ_ONCE(memcg->zswap_writeback));
return 0;
}
static ssize_t zswap_writeback_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
int zswap_writeback;
ssize_t parse_ret = kstrtoint(strstrip(buf), 0, &zswap_writeback);
if (parse_ret)
return parse_ret;
if (zswap_writeback != 0 && zswap_writeback != 1)
return -EINVAL;
WRITE_ONCE(memcg->zswap_writeback, zswap_writeback);
return nbytes;
}
static struct cftype zswap_files[] = {
{
.name = "zswap.current",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = zswap_current_read,
},
{
.name = "zswap.max",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = zswap_max_show,
.write = zswap_max_write,
},
{
.name = "zswap.writeback",
.seq_show = zswap_writeback_show,
.write = zswap_writeback_write,
},
{ } /* terminate */
};
#endif /* CONFIG_MEMCG_KMEM && CONFIG_ZSWAP */
static int __init mem_cgroup_swap_init(void)
{
if (mem_cgroup_disabled())
return 0;
WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files));
WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files));
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, zswap_files));
#endif
return 0;
}
subsys_initcall(mem_cgroup_swap_init);
#endif /* CONFIG_SWAP */
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