blob: ba9138a4a1de37f744eaf488fc0930b82f60b3e1 [file] [log] [blame]
// 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
*/
#include <linux/page_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/shmem_fs.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.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/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/tracehook.h>
#include "internal.h"
#include <net/sock.h>
#include <net/ip.h>
#include "slab.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;
#define MEM_CGROUP_RECLAIM_RETRIES 5
/* Socket memory accounting disabled? */
static bool cgroup_memory_nosocket;
/* Kernel memory accounting disabled? */
static bool cgroup_memory_nokmem;
/* Whether the swap controller is active */
#ifdef CONFIG_MEMCG_SWAP
int do_swap_account __read_mostly;
#else
#define do_swap_account 0
#endif
/* Whether legacy memory+swap accounting is active */
static bool do_memsw_account(void)
{
return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && do_swap_account;
}
static const char *const mem_cgroup_lru_names[] = {
"inactive_anon",
"active_anon",
"inactive_file",
"active_file",
"unevictable",
};
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
#define NUMAINFO_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_hierarchical_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
enum charge_type {
MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
MEM_CGROUP_CHARGE_TYPE_ANON,
MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */
NR_CHARGE_TYPE,
};
/* for encoding cft->private value on file */
enum res_type {
_MEM,
_MEMSWAP,
_OOM_TYPE,
_KMEM,
_TCP,
};
#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
#define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
/* Used for OOM nofiier */
#define OOM_CONTROL (0)
/*
* 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 should_force_charge(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 cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr)
{
return &container_of(vmpr, struct mem_cgroup, vmpressure)->css;
}
#ifdef CONFIG_MEMCG_KMEM
/*
* This will be the memcg's index in each cache's ->memcg_params.memcg_caches.
* The main reason for not using cgroup id for this:
* this works better in sparse environments, where we have a lot of memcgs,
* but only a few kmem-limited. Or also, if we have, for instance, 200
* memcgs, and none but the 200th is kmem-limited, we'd have to have a
* 200 entry array for that.
*
* The current size of the caches array is stored in memcg_nr_cache_ids. It
* will double each time we have to increase it.
*/
static DEFINE_IDA(memcg_cache_ida);
int memcg_nr_cache_ids;
/* Protects memcg_nr_cache_ids */
static DECLARE_RWSEM(memcg_cache_ids_sem);
void memcg_get_cache_ids(void)
{
down_read(&memcg_cache_ids_sem);
}
void memcg_put_cache_ids(void)
{
up_read(&memcg_cache_ids_sem);
}
/*
* MIN_SIZE is different than 1, because we would like to avoid going through
* the alloc/free process all the time. In a small machine, 4 kmem-limited
* cgroups is a reasonable guess. In the future, it could be a parameter or
* tunable, but that is strictly not necessary.
*
* MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
* this constant directly from cgroup, but it is understandable that this is
* better kept as an internal representation in cgroup.c. In any case, the
* cgrp_id space is not getting any smaller, and we don't have to necessarily
* increase ours as well if it increases.
*/
#define MEMCG_CACHES_MIN_SIZE 4
#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX
/*
* A lot of the calls to the cache allocation functions are expected to be
* inlined by the compiler. Since the calls to memcg_kmem_get_cache 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_enabled_key);
EXPORT_SYMBOL(memcg_kmem_enabled_key);
struct workqueue_struct *memcg_kmem_cache_wq;
static int memcg_shrinker_map_size;
static DEFINE_MUTEX(memcg_shrinker_map_mutex);
static void memcg_free_shrinker_map_rcu(struct rcu_head *head)
{
kvfree(container_of(head, struct memcg_shrinker_map, rcu));
}
static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg,
int size, int old_size)
{
struct memcg_shrinker_map *new, *old;
int nid;
lockdep_assert_held(&memcg_shrinker_map_mutex);
for_each_node(nid) {
old = rcu_dereference_protected(
mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true);
/* Not yet online memcg */
if (!old)
return 0;
new = kvmalloc(sizeof(*new) + size, GFP_KERNEL);
if (!new)
return -ENOMEM;
/* Set all old bits, clear all new bits */
memset(new->map, (int)0xff, old_size);
memset((void *)new->map + old_size, 0, size - old_size);
rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new);
call_rcu(&old->rcu, memcg_free_shrinker_map_rcu);
}
return 0;
}
static void memcg_free_shrinker_maps(struct mem_cgroup *memcg)
{
struct mem_cgroup_per_node *pn;
struct memcg_shrinker_map *map;
int nid;
if (mem_cgroup_is_root(memcg))
return;
for_each_node(nid) {
pn = mem_cgroup_nodeinfo(memcg, nid);
map = rcu_dereference_protected(pn->shrinker_map, true);
if (map)
kvfree(map);
rcu_assign_pointer(pn->shrinker_map, NULL);
}
}
static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
{
struct memcg_shrinker_map *map;
int nid, size, ret = 0;
if (mem_cgroup_is_root(memcg))
return 0;
mutex_lock(&memcg_shrinker_map_mutex);
size = memcg_shrinker_map_size;
for_each_node(nid) {
map = kvzalloc(sizeof(*map) + size, GFP_KERNEL);
if (!map) {
memcg_free_shrinker_maps(memcg);
ret = -ENOMEM;
break;
}
rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map);
}
mutex_unlock(&memcg_shrinker_map_mutex);
return ret;
}
int memcg_expand_shrinker_maps(int new_id)
{
int size, old_size, ret = 0;
struct mem_cgroup *memcg;
size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long);
old_size = memcg_shrinker_map_size;
if (size <= old_size)
return 0;
mutex_lock(&memcg_shrinker_map_mutex);
if (!root_mem_cgroup)
goto unlock;
for_each_mem_cgroup(memcg) {
if (mem_cgroup_is_root(memcg))
continue;
ret = memcg_expand_one_shrinker_map(memcg, size, old_size);
if (ret)
goto unlock;
}
unlock:
if (!ret)
memcg_shrinker_map_size = size;
mutex_unlock(&memcg_shrinker_map_mutex);
return ret;
}
void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
{
if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
struct memcg_shrinker_map *map;
rcu_read_lock();
map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map);
/* Pairs with smp mb in shrink_slab() */
smp_mb__before_atomic();
set_bit(shrinker_id, map->map);
rcu_read_unlock();
}
}
#else /* CONFIG_MEMCG_KMEM */
static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
{
return 0;
}
static void memcg_free_shrinker_maps(struct mem_cgroup *memcg) { }
#endif /* CONFIG_MEMCG_KMEM */
/**
* mem_cgroup_css_from_page - css of the memcg associated with a page
* @page: page of interest
*
* If memcg is bound to the default hierarchy, css of the memcg associated
* with @page is returned. The returned css remains associated with @page
* 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_page(struct page *page)
{
struct mem_cgroup *memcg;
memcg = page->mem_cgroup;
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();
memcg = READ_ONCE(page->mem_cgroup);
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 struct mem_cgroup_per_node *
mem_cgroup_page_nodeinfo(struct mem_cgroup *memcg, struct page *page)
{
int nid = page_to_nid(page);
return memcg->nodeinfo[nid];
}
static struct mem_cgroup_tree_per_node *
soft_limit_tree_node(int nid)
{
return soft_limit_tree.rb_tree_per_node[nid];
}
static struct mem_cgroup_tree_per_node *
soft_limit_tree_from_page(struct page *page)
{
int nid = page_to_nid(page);
return soft_limit_tree.rb_tree_per_node[nid];
}
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;
}
/*
* We can't avoid mem cgroups that are over their soft
* limit by the same amount
*/
else if (mz->usage_in_excess >= mz_node->usage_in_excess)
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, struct page *page)
{
unsigned long excess;
struct mem_cgroup_per_node *mz;
struct mem_cgroup_tree_per_node *mctz;
mctz = soft_limit_tree_from_page(page);
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 = mem_cgroup_page_nodeinfo(memcg, page);
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 = mem_cgroup_nodeinfo(memcg, nid);
mctz = soft_limit_tree_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_online(&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;
}
/**
* __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)
{
long x;
if (mem_cgroup_disabled())
return;
__this_cpu_add(memcg->vmstats_local->stat[idx], val);
x = val + __this_cpu_read(memcg->vmstats_percpu->stat[idx]);
if (unlikely(abs(x) > MEMCG_CHARGE_BATCH)) {
struct mem_cgroup *mi;
for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
atomic_long_add(x, &mi->vmstats[idx]);
x = 0;
}
__this_cpu_write(memcg->vmstats_percpu->stat[idx], x);
}
static struct mem_cgroup_per_node *
parent_nodeinfo(struct mem_cgroup_per_node *pn, int nid)
{
struct mem_cgroup *parent;
parent = parent_mem_cgroup(pn->memcg);
if (!parent)
return NULL;
return mem_cgroup_nodeinfo(parent, nid);
}
/**
* __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)
{
pg_data_t *pgdat = lruvec_pgdat(lruvec);
struct mem_cgroup_per_node *pn;
struct mem_cgroup *memcg;
long x;
/* Update node */
__mod_node_page_state(pgdat, idx, val);
if (mem_cgroup_disabled())
return;
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
memcg = pn->memcg;
/* Update memcg */
__mod_memcg_state(memcg, idx, val);
/* Update lruvec */
__this_cpu_add(pn->lruvec_stat_local->count[idx], val);
x = val + __this_cpu_read(pn->lruvec_stat_cpu->count[idx]);
if (unlikely(abs(x) > MEMCG_CHARGE_BATCH)) {
struct mem_cgroup_per_node *pi;
for (pi = pn; pi; pi = parent_nodeinfo(pi, pgdat->node_id))
atomic_long_add(x, &pi->lruvec_stat[idx]);
x = 0;
}
__this_cpu_write(pn->lruvec_stat_cpu->count[idx], x);
}
/**
* __count_memcg_events - account VM events in a cgroup
* @memcg: the memory cgroup
* @idx: the event item
* @count: the number of events that occured
*/
void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
unsigned long count)
{
unsigned long x;
if (mem_cgroup_disabled())
return;
__this_cpu_add(memcg->vmstats_local->events[idx], count);
x = count + __this_cpu_read(memcg->vmstats_percpu->events[idx]);
if (unlikely(x > MEMCG_CHARGE_BATCH)) {
struct mem_cgroup *mi;
for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
atomic_long_add(x, &mi->vmevents[idx]);
x = 0;
}
__this_cpu_write(memcg->vmstats_percpu->events[idx], x);
}
static unsigned long memcg_events(struct mem_cgroup *memcg, int event)
{
return atomic_long_read(&memcg->vmevents[event]);
}
static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
{
long x = 0;
int cpu;
for_each_possible_cpu(cpu)
x += per_cpu(memcg->vmstats_local->events[event], cpu);
return x;
}
static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
struct page *page,
bool compound, int nr_pages)
{
/*
* Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
* counted as CACHE even if it's on ANON LRU.
*/
if (PageAnon(page))
__mod_memcg_state(memcg, MEMCG_RSS, nr_pages);
else {
__mod_memcg_state(memcg, MEMCG_CACHE, nr_pages);
if (PageSwapBacked(page))
__mod_memcg_state(memcg, NR_SHMEM, nr_pages);
}
if (compound) {
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
__mod_memcg_state(memcg, MEMCG_RSS_HUGE, 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;
case MEM_CGROUP_TARGET_NUMAINFO:
next = val + NUMAINFO_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, struct page *page)
{
/* threshold event is triggered in finer grain than soft limit */
if (unlikely(mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_THRESH))) {
bool do_softlimit;
bool do_numainfo __maybe_unused;
do_softlimit = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_SOFTLIMIT);
#if MAX_NUMNODES > 1
do_numainfo = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_NUMAINFO);
#endif
mem_cgroup_threshold(memcg);
if (unlikely(do_softlimit))
mem_cgroup_update_tree(memcg, page);
#if MAX_NUMNODES > 1
if (unlikely(do_numainfo))
atomic_inc(&memcg->numainfo_events);
#endif
}
}
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);
/**
* 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. Otherwise
* root_mem_cgroup is returned. However 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;
rcu_read_lock();
do {
/*
* Page cache insertions can happen withou an
* actual mm context, e.g. during disk probing
* on boot, loopback IO, acct() writes etc.
*/
if (unlikely(!mm))
memcg = root_mem_cgroup;
else {
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))
memcg = root_mem_cgroup;
}
} while (!css_tryget_online(&memcg->css));
rcu_read_unlock();
return memcg;
}
EXPORT_SYMBOL(get_mem_cgroup_from_mm);
/**
* get_mem_cgroup_from_page: Obtain a reference on given page's memcg.
* @page: page from which memcg should be extracted.
*
* Obtain a reference on page->memcg and returns it if successful. Otherwise
* root_mem_cgroup is returned.
*/
struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
{
struct mem_cgroup *memcg = page->mem_cgroup;
if (mem_cgroup_disabled())
return NULL;
rcu_read_lock();
if (!memcg || !css_tryget_online(&memcg->css))
memcg = root_mem_cgroup;
rcu_read_unlock();
return memcg;
}
EXPORT_SYMBOL(get_mem_cgroup_from_page);
/**
* If current->active_memcg is non-NULL, do not fallback to current->mm->memcg.
*/
static __always_inline struct mem_cgroup *get_mem_cgroup_from_current(void)
{
if (unlikely(current->active_memcg)) {
struct mem_cgroup *memcg = root_mem_cgroup;
rcu_read_lock();
if (css_tryget_online(&current->active_memcg->css))
memcg = current->active_memcg;
rcu_read_unlock();
return memcg;
}
return get_mem_cgroup_from_mm(current->mm);
}
/**
* 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 and a priority level in @reclaim to
* divide up the memcgs in the hierarchy among all concurrent
* reclaimers operating on the same node and priority.
*/
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 *uninitialized_var(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;
if (prev && !reclaim)
pos = prev;
if (!root->use_hierarchy && root != root_mem_cgroup) {
if (prev)
goto out;
return root;
}
rcu_read_lock();
if (reclaim) {
struct mem_cgroup_per_node *mz;
mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id);
iter = &mz->iter[reclaim->priority];
if (prev && 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);
}
}
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.
*/
memcg = mem_cgroup_from_css(css);
if (css == &root->css)
break;
if (css_tryget(css))
break;
memcg = NULL;
}
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++;
else if (!prev)
reclaim->generation = iter->generation;
}
out_unlock:
rcu_read_unlock();
out:
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 *dead_memcg)
{
struct mem_cgroup *memcg = dead_memcg;
struct mem_cgroup_reclaim_iter *iter;
struct mem_cgroup_per_node *mz;
int nid;
int i;
for (; memcg; memcg = parent_mem_cgroup(memcg)) {
for_each_node(nid) {
mz = mem_cgroup_nodeinfo(memcg, nid);
for (i = 0; i <= DEF_PRIORITY; i++) {
iter = &mz->iter[i];
cmpxchg(&iter->position,
dead_memcg, NULL);
}
}
}
}
/**
* 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 and returns the value.
* Otherwise, it will iterate over all tasks and return 0.
*
* This function must not be called for the root memory cgroup.
*/
int 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(memcg == root_mem_cgroup);
for_each_mem_cgroup_tree(iter, memcg) {
struct css_task_iter it;
struct task_struct *task;
css_task_iter_start(&iter->css, 0, &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;
}
}
return ret;
}
/**
* mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
* @page: the page
* @pgdat: pgdat of the page
*
* This function is only safe when following the LRU page isolation
* and putback protocol: the LRU lock must be held, and the page must
* either be PageLRU() or the caller must have isolated/allocated it.
*/
struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat)
{
struct mem_cgroup_per_node *mz;
struct mem_cgroup *memcg;
struct lruvec *lruvec;
if (mem_cgroup_disabled()) {
lruvec = &pgdat->lruvec;
goto out;
}
memcg = page->mem_cgroup;
/*
* Swapcache readahead pages are added to the LRU - and
* possibly migrated - before they are charged.
*/
if (!memcg)
memcg = root_mem_cgroup;
mz = mem_cgroup_page_nodeinfo(memcg, page);
lruvec = &mz->lruvec;
out:
/*
* Since a node can be onlined after the mem_cgroup was created,
* we have to be prepared to initialize lruvec->zone here;
* and if offlined then reonlined, we need to reinitialize it.
*/
if (unlikely(lruvec->pgdat != pgdat))
lruvec->pgdat = pgdat;
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 (that ordering being
* so as to allow it to check that lru_size 0 is consistent with list_empty).
*/
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;
}
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg)
{
struct mem_cgroup *task_memcg;
struct task_struct *p;
bool ret;
p = find_lock_task_mm(task);
if (p) {
task_memcg = get_mem_cgroup_from_mm(p->mm);
task_unlock(p);
} else {
/*
* All threads may have already detached their mm's, but the oom
* killer still needs to detect if they have already been oom
* killed to prevent needlessly killing additional tasks.
*/
rcu_read_lock();
task_memcg = mem_cgroup_from_task(task);
css_get(&task_memcg->css);
rcu_read_unlock();
}
ret = mem_cgroup_is_descendant(task_memcg, memcg);
css_put(&task_memcg->css);
return ret;
}
/**
* 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;
}
static const unsigned int memcg1_stats[] = {
MEMCG_CACHE,
MEMCG_RSS,
MEMCG_RSS_HUGE,
NR_SHMEM,
NR_FILE_MAPPED,
NR_FILE_DIRTY,
NR_WRITEBACK,
MEMCG_SWAP,
};
static const char *const memcg1_stat_names[] = {
"cache",
"rss",
"rss_huge",
"shmem",
"mapped_file",
"dirty",
"writeback",
"swap",
};
#define K(x) ((x) << (PAGE_SHIFT-10))
/**
* 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)
{
struct mem_cgroup *iter;
unsigned int i;
pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memory)),
K((u64)memcg->memory.max), memcg->memory.failcnt);
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);
for_each_mem_cgroup_tree(iter, memcg) {
pr_info("Memory cgroup stats for ");
pr_cont_cgroup_path(iter->css.cgroup);
pr_cont(":");
for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
if (memcg1_stats[i] == MEMCG_SWAP && !do_swap_account)
continue;
pr_cont(" %s:%luKB", memcg1_stat_names[i],
K(memcg_page_state_local(iter,
memcg1_stats[i])));
}
for (i = 0; i < NR_LRU_LISTS; i++)
pr_cont(" %s:%luKB", mem_cgroup_lru_names[i],
K(memcg_page_state_local(iter,
NR_LRU_BASE + i)));
pr_cont("\n");
}
}
/*
* Return the memory (and swap, if configured) limit for a memcg.
*/
unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
{
unsigned long max;
max = memcg->memory.max;
if (mem_cgroup_swappiness(memcg)) {
unsigned long memsw_max;
unsigned long swap_max;
memsw_max = memcg->memsw.max;
swap_max = memcg->swap.max;
swap_max = min(swap_max, (unsigned long)total_swap_pages);
max = min(max + swap_max, memsw_max);
}
return max;
}
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;
if (mutex_lock_killable(&oom_lock))
return true;
/*
* A few threads which were not waiting at mutex_lock_killable() can
* fail to bail out. Therefore, check again after holding oom_lock.
*/
ret = should_force_charge() || out_of_memory(&oc);
mutex_unlock(&oom_lock);
return ret;
}
#if MAX_NUMNODES > 1
/**
* test_mem_cgroup_node_reclaimable
* @memcg: the target memcg
* @nid: the node ID to be checked.
* @noswap : specify true here if the user wants flle only information.
*
* This function returns whether the specified memcg contains any
* reclaimable pages on a node. Returns true if there are any reclaimable
* pages in the node.
*/
static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
int nid, bool noswap)
{
struct lruvec *lruvec = mem_cgroup_lruvec(NODE_DATA(nid), memcg);
if (lruvec_page_state(lruvec, NR_INACTIVE_FILE) ||
lruvec_page_state(lruvec, NR_ACTIVE_FILE))
return true;
if (noswap || !total_swap_pages)
return false;
if (lruvec_page_state(lruvec, NR_INACTIVE_ANON) ||
lruvec_page_state(lruvec, NR_ACTIVE_ANON))
return true;
return false;
}
/*
* Always updating the nodemask is not very good - even if we have an empty
* list or the wrong list here, we can start from some node and traverse all
* nodes based on the zonelist. So update the list loosely once per 10 secs.
*
*/
static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
{
int nid;
/*
* numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
* pagein/pageout changes since the last update.
*/
if (!atomic_read(&memcg->numainfo_events))
return;
if (atomic_inc_return(&memcg->numainfo_updating) > 1)
return;
/* make a nodemask where this memcg uses memory from */
memcg->scan_nodes = node_states[N_MEMORY];
for_each_node_mask(nid, node_states[N_MEMORY]) {
if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
node_clear(nid, memcg->scan_nodes);
}
atomic_set(&memcg->numainfo_events, 0);
atomic_set(&memcg->numainfo_updating, 0);
}
/*
* Selecting a node where we start reclaim from. Because what we need is just
* reducing usage counter, start from anywhere is O,K. Considering
* memory reclaim from current node, there are pros. and cons.
*
* Freeing memory from current node means freeing memory from a node which
* we'll use or we've used. So, it may make LRU bad. And if several threads
* hit limits, it will see a contention on a node. But freeing from remote
* node means more costs for memory reclaim because of memory latency.
*
* Now, we use round-robin. Better algorithm is welcomed.
*/
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
{
int node;
mem_cgroup_may_update_nodemask(memcg);
node = memcg->last_scanned_node;
node = next_node_in(node, memcg->scan_nodes);
/*
* mem_cgroup_may_update_nodemask might have seen no reclaimmable pages
* last time it really checked all the LRUs due to rate limiting.
* Fallback to the current node in that case for simplicity.
*/
if (unlikely(node == MAX_NUMNODES))
node = numa_node_id();
memcg->last_scanned_node = node;
return node;
}
#else
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
{
return 0;
}
#endif
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,
.priority = 0,
};
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, 1, _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;
/*
* When a new child is created while the hierarchy is under oom,
* mem_cgroup_oom_lock() may not be called. Watch for underflow.
*/
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);
}
enum oom_status {
OOM_SUCCESS,
OOM_FAILED,
OOM_ASYNC,
OOM_SKIPPED
};
static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
{
enum oom_status ret;
bool locked;
if (order > PAGE_ALLOC_COSTLY_ORDER)
return OOM_SKIPPED;
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 (memcg->oom_kill_disable) {
if (!current->in_user_fault)
return OOM_SKIPPED;
css_get(&memcg->css);
current->memcg_in_oom = memcg;
current->memcg_oom_gfp_mask = mask;
current->memcg_oom_order = order;
return OOM_ASYNC;
}
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);
if (mem_cgroup_out_of_memory(memcg, mask, order))
ret = OOM_SUCCESS;
else
ret = OOM_FAILED;
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);
if (locked && !memcg->oom_kill_disable) {
mem_cgroup_unmark_under_oom(memcg);
finish_wait(&memcg_oom_waitq, &owait.wait);
mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
current->memcg_oom_order);
} else {
schedule();
mem_cgroup_unmark_under_oom(memcg);
finish_wait(&memcg_oom_waitq, &owait.wait);
}
if (locked) {
mem_cgroup_oom_unlock(memcg);
/*
* There is no guarantee that an OOM-lock contender
* sees the wakeups triggered by the OOM kill
* uncharges. Wake any sleepers explicitely.
*/
memcg_oom_recover(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 (memcg == root_mem_cgroup)
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 (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");
}
/**
* lock_page_memcg - lock a page->mem_cgroup binding
* @page: the page
*
* This function protects unlocked LRU pages from being moved to
* another cgroup.
*
* It ensures lifetime of the returned memcg. Caller is responsible
* for the lifetime of the page; __unlock_page_memcg() is available
* when @page might get freed inside the locked section.
*/
struct mem_cgroup *lock_page_memcg(struct page *page)
{
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.
*
* The RCU lock also protects the memcg from being freed when
* the page state that is going to change is the only thing
* preventing the page itself from being freed. E.g. writeback
* doesn't hold a page reference and relies on PG_writeback to
* keep off truncation, migration and so forth.
*/
rcu_read_lock();
if (mem_cgroup_disabled())
return NULL;
again:
memcg = page->mem_cgroup;
if (unlikely(!memcg))
return NULL;
if (atomic_read(&memcg->moving_account) <= 0)
return memcg;
spin_lock_irqsave(&memcg->move_lock, flags);
if (memcg != page->mem_cgroup) {
spin_unlock_irqrestore(&memcg->move_lock, flags);
goto again;
}
/*
* When charge migration first begins, we can have locked and
* unlocked page stat updates happening concurrently. Track
* the task who has the lock for unlock_page_memcg().
*/
memcg->move_lock_task = current;
memcg->move_lock_flags = flags;
return memcg;
}
EXPORT_SYMBOL(lock_page_memcg);
/**
* __unlock_page_memcg - unlock and unpin a memcg
* @memcg: the memcg
*
* Unlock and unpin a memcg returned by lock_page_memcg().
*/
void __unlock_page_memcg(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();
}
/**
* unlock_page_memcg - unlock a page->mem_cgroup binding
* @page: the page
*/
void unlock_page_memcg(struct page *page)
{
__unlock_page_memcg(page->mem_cgroup);
}
EXPORT_SYMBOL(unlock_page_memcg);
struct memcg_stock_pcp {
struct mem_cgroup *cached; /* this never be root cgroup */
unsigned int nr_pages;
struct work_struct work;
unsigned long flags;
#define FLUSHING_CACHED_CHARGE 0
};
static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
static DEFINE_MUTEX(percpu_charge_mutex);
/**
* 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_irq_save(flags);
stock = this_cpu_ptr(&memcg_stock);
if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
stock->nr_pages -= nr_pages;
ret = true;
}
local_irq_restore(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 = stock->cached;
if (stock->nr_pages) {
page_counter_uncharge(&old->memory, stock->nr_pages);
if (do_memsw_account())
page_counter_uncharge(&old->memsw, stock->nr_pages);
css_put_many(&old->css, stock->nr_pages);
stock->nr_pages = 0;
}
stock->cached = NULL;
}
static void drain_local_stock(struct work_struct *dummy)
{
struct memcg_stock_pcp *stock;
unsigned long flags;
/*
* The only protection from memory hotplug vs. drain_stock races is
* that we always operate on local CPU stock here with IRQ disabled
*/
local_irq_save(flags);
stock = this_cpu_ptr(&memcg_stock);
drain_stock(stock);
clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
local_irq_restore(flags);
}
/*
* 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;
unsigned long flags;
local_irq_save(flags);
stock = this_cpu_ptr(&memcg_stock);
if (stock->cached != memcg) { /* reset if necessary */
drain_stock(stock);
stock->cached = memcg;
}
stock->nr_pages += nr_pages;
if (stock->nr_pages > MEMCG_CHARGE_BATCH)
drain_stock(stock);
local_irq_restore(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.
*/
curcpu = get_cpu();
for_each_online_cpu(cpu) {
struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
struct mem_cgroup *memcg;
memcg = stock->cached;
if (!memcg || !stock->nr_pages || !css_tryget(&memcg->css))
continue;
if (!mem_cgroup_is_descendant(memcg, root_memcg)) {
css_put(&memcg->css);
continue;
}
if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
if (cpu == curcpu)
drain_local_stock(&stock->work);
else
schedule_work_on(cpu, &stock->work);
}
css_put(&memcg->css);
}
put_cpu();
mutex_unlock(&percpu_charge_mutex);
}
static int memcg_hotplug_cpu_dead(unsigned int cpu)
{
struct memcg_stock_pcp *stock;
struct mem_cgroup *memcg, *mi;
stock = &per_cpu(memcg_stock, cpu);
drain_stock(stock);
for_each_mem_cgroup(memcg) {
int i;
for (i = 0; i < MEMCG_NR_STAT; i++) {
int nid;
long x;
x = this_cpu_xchg(memcg->vmstats_percpu->stat[i], 0);
if (x)
for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
atomic_long_add(x, &memcg->vmstats[i]);
if (i >= NR_VM_NODE_STAT_ITEMS)
continue;
for_each_node(nid) {
struct mem_cgroup_per_node *pn;
pn = mem_cgroup_nodeinfo(memcg, nid);
x = this_cpu_xchg(pn->lruvec_stat_cpu->count[i], 0);
if (x)
do {
atomic_long_add(x, &pn->lruvec_stat[i]);
} while ((pn = parent_nodeinfo(pn, nid)));
}
}
for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
long x;
x = this_cpu_xchg(memcg->vmstats_percpu->events[i], 0);
if (x)
for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
atomic_long_add(x, &memcg->vmevents[i]);
}
}
return 0;
}
static void reclaim_high(struct mem_cgroup *memcg,
unsigned int nr_pages,
gfp_t gfp_mask)
{
do {
if (page_counter_read(&memcg->memory) <= memcg->high)
continue;
memcg_memory_event(memcg, MEMCG_HIGH);
try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true);
} while ((memcg = parent_mem_cgroup(memcg)));
}
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);
}
/*
* Scheduled by try_charge() to be executed from the userland return path
* and reclaims memory over the high limit.
*/
void mem_cgroup_handle_over_high(void)
{
unsigned int nr_pages = current->memcg_nr_pages_over_high;
struct mem_cgroup *memcg;
if (likely(!nr_pages))
return;
memcg = get_mem_cgroup_from_mm(current->mm);
reclaim_high(memcg, nr_pages, GFP_KERNEL);
css_put(&memcg->css);
current->memcg_nr_pages_over_high = 0;
}
static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
unsigned int nr_pages)
{
unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);
int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
struct mem_cgroup *mem_over_limit;
struct page_counter *counter;
unsigned long nr_reclaimed;
bool may_swap = true;
bool drained = false;
bool oomed = false;
enum oom_status oom_status;
if (mem_cgroup_is_root(memcg))
return 0;
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);
may_swap = false;
}
if (batch > nr_pages) {
batch = nr_pages;
goto retry;
}
/*
* Unlike in global OOM situations, memcg is not in a physical
* memory shortage. Allow dying and OOM-killed tasks to
* bypass the last charges so that they can exit quickly and
* free their memory.
*/
if (unlikely(should_force_charge()))
goto force;
/*
* 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);
nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages,
gfp_mask, may_swap);
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 && oomed)
goto nomem;
if (gfp_mask & __GFP_NOFAIL)
goto force;
if (fatal_signal_pending(current))
goto force;
/*
* 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.
*/
oom_status = mem_cgroup_oom(mem_over_limit, gfp_mask,
get_order(nr_pages * PAGE_SIZE));
switch (oom_status) {
case OOM_SUCCESS:
nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
oomed = true;
goto retry;
case OOM_FAILED:
goto force;
default:
goto nomem;
}
nomem:
if (!(gfp_mask & __GFP_NOFAIL))
return -ENOMEM;
force:
/*
* 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);
css_get_many(&memcg->css, nr_pages);
return 0;
done_restock:
css_get_many(&memcg->css, batch);
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 {
if (page_counter_read(&memcg->memory) > memcg->high) {
/* Don't bother a random interrupted task */
if (in_interrupt()) {
schedule_work(&memcg->high_work);
break;
}
current->memcg_nr_pages_over_high += batch;
set_notify_resume(current);
break;
}
} while ((memcg = parent_mem_cgroup(memcg)));
return 0;
}
static void 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);
css_put_many(&memcg->css, nr_pages);
}
static void lock_page_lru(struct page *page, int *isolated)
{
pg_data_t *pgdat = page_pgdat(page);
spin_lock_irq(&pgdat->lru_lock);
if (PageLRU(page)) {
struct lruvec *lruvec;
lruvec = mem_cgroup_page_lruvec(page, pgdat);
ClearPageLRU(page);
del_page_from_lru_list(page, lruvec, page_lru(page));
*isolated = 1;
} else
*isolated = 0;
}
static void unlock_page_lru(struct page *page, int isolated)
{
pg_data_t *pgdat = page_pgdat(page);
if (isolated) {
struct lruvec *lruvec;
lruvec = mem_cgroup_page_lruvec(page, pgdat);
VM_BUG_ON_PAGE(PageLRU(page), page);
SetPageLRU(page);
add_page_to_lru_list(page, lruvec, page_lru(page));
}
spin_unlock_irq(&pgdat->lru_lock);
}
static void commit_charge(struct page *page, struct mem_cgroup *memcg,
bool lrucare)
{
int isolated;
VM_BUG_ON_PAGE(page->mem_cgroup, page);
/*
* In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
* may already be on some other mem_cgroup's LRU. Take care of it.
*/
if (lrucare)
lock_page_lru(page, &isolated);
/*
* Nobody should be changing or seriously looking at
* page->mem_cgroup at this point:
*
* - the page is uncharged
*
* - the page is off-LRU
*
* - an anonymous fault has exclusive page access, except for
* a locked page table
*
* - a page cache insertion, a swapin fault, or a migration
* have the page locked
*/
page->mem_cgroup = memcg;
if (lrucare)
unlock_page_lru(page, isolated);
}
#ifdef CONFIG_MEMCG_KMEM
static int memcg_alloc_cache_id(void)
{
int id, size;
int err;
id = ida_simple_get(&memcg_cache_ida,
0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
if (id < 0)
return id;
if (id < memcg_nr_cache_ids)
return id;
/*
* There's no space for the new id in memcg_caches arrays,
* so we have to grow them.
*/
down_write(&memcg_cache_ids_sem);
size = 2 * (id + 1);
if (size < MEMCG_CACHES_MIN_SIZE)
size = MEMCG_CACHES_MIN_SIZE;
else if (size > MEMCG_CACHES_MAX_SIZE)
size = MEMCG_CACHES_MAX_SIZE;
err = memcg_update_all_caches(size);
if (!err)
err = memcg_update_all_list_lrus(size);
if (!err)
memcg_nr_cache_ids = size;
up_write(&memcg_cache_ids_sem);
if (err) {
ida_simple_remove(&memcg_cache_ida, id);
return err;
}
return id;
}
static void memcg_free_cache_id(int id)
{
ida_simple_remove(&memcg_cache_ida, id);
}
struct memcg_kmem_cache_create_work {
struct mem_cgroup *memcg;
struct kmem_cache *cachep;
struct work_struct work;
};
static void memcg_kmem_cache_create_func(struct work_struct *w)
{
struct memcg_kmem_cache_create_work *cw =
container_of(w, struct memcg_kmem_cache_create_work, work);
struct mem_cgroup *memcg = cw->memcg;
struct kmem_cache *cachep = cw->cachep;
memcg_create_kmem_cache(memcg, cachep);
css_put(&memcg->css);
kfree(cw);
}
/*
* Enqueue the creation of a per-memcg kmem_cache.
*/
static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
struct kmem_cache *cachep)
{
struct memcg_kmem_cache_create_work *cw;
cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN);
if (!cw)
return;
css_get(&memcg->css);
cw->memcg = memcg;
cw->cachep = cachep;
INIT_WORK(&cw->work, memcg_kmem_cache_create_func);
queue_work(memcg_kmem_cache_wq, &cw->work);
}
static inline bool memcg_kmem_bypass(void)
{
if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD))
return true;
return false;
}
/**
* memcg_kmem_get_cache: select the correct per-memcg cache for allocation
* @cachep: the original global kmem cache
*
* Return the kmem_cache we're supposed to use for a slab allocation.
* We try to use the current memcg's version of the cache.
*
* If the cache does not exist yet, if we are the first user of it, we
* create it asynchronously in a workqueue and let the current allocation
* go through with the original cache.
*
* This function takes a reference to the cache it returns to assure it
* won't get destroyed while we are working with it. Once the caller is
* done with it, memcg_kmem_put_cache() must be called to release the
* reference.
*/
struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
{
struct mem_cgroup *memcg;
struct kmem_cache *memcg_cachep;
int kmemcg_id;
VM_BUG_ON(!is_root_cache(cachep));
if (memcg_kmem_bypass())
return cachep;
memcg = get_mem_cgroup_from_current();
kmemcg_id = READ_ONCE(memcg->kmemcg_id);
if (kmemcg_id < 0)
goto out;
memcg_cachep = cache_from_memcg_idx(cachep, kmemcg_id);
if (likely(memcg_cachep))
return memcg_cachep;
/*
* If we are in a safe context (can wait, and not in interrupt
* context), we could be be predictable and return right away.
* This would guarantee that the allocation being performed
* already belongs in the new cache.
*
* However, there are some clashes that can arrive from locking.
* For instance, because we acquire the slab_mutex while doing
* memcg_create_kmem_cache, this means no further allocation
* could happen with the slab_mutex held. So it's better to
* defer everything.
*/
memcg_schedule_kmem_cache_create(memcg, cachep);
out:
css_put(&memcg->css);
return cachep;
}
/**
* memcg_kmem_put_cache: drop reference taken by memcg_kmem_get_cache
* @cachep: the cache returned by memcg_kmem_get_cache
*/
void memcg_kmem_put_cache(struct kmem_cache *cachep)
{
if (!is_root_cache(cachep))
css_put(&cachep->memcg_params.memcg->css);
}
/**
* __memcg_kmem_charge_memcg: charge a kmem page
* @page: page to charge
* @gfp: reclaim mode
* @order: allocation order
* @memcg: memory cgroup to charge
*
* Returns 0 on success, an error code on failure.
*/
int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
struct mem_cgroup *memcg)
{
unsigned int nr_pages = 1 << order;
struct page_counter *counter;
int ret;
ret = try_charge(memcg, gfp, nr_pages);
if (ret)
return ret;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
!page_counter_try_charge(&memcg->kmem, nr_pages, &counter)) {
cancel_charge(memcg, nr_pages);
return -ENOMEM;
}
page->mem_cgroup = memcg;
return 0;
}
/**
* __memcg_kmem_charge: 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(struct page *page, gfp_t gfp, int order)
{
struct mem_cgroup *memcg;
int ret = 0;
if (memcg_kmem_bypass())
return 0;
memcg = get_mem_cgroup_from_current();
if (!mem_cgroup_is_root(memcg)) {
ret = __memcg_kmem_charge_memcg(page, gfp, order, memcg);
if (!ret)
__SetPageKmemcg(page);
}
css_put(&memcg->css);
return ret;
}
/**
* __memcg_kmem_uncharge: uncharge a kmem page
* @page: page to uncharge
* @order: allocation order
*/
void __memcg_kmem_uncharge(struct page *page, int order)
{
struct mem_cgroup *memcg = page->mem_cgroup;
unsigned int nr_pages = 1 << order;
if (!memcg)
return;
VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
page_counter_uncharge(&memcg->kmem, nr_pages);
page_counter_uncharge(&memcg->memory, nr_pages);
if (do_memsw_account())
page_counter_uncharge(&memcg->memsw, nr_pages);
page->mem_cgroup = NULL;
/* slab pages do not have PageKmemcg flag set */
if (PageKmemcg(page))
__ClearPageKmemcg(page);
css_put_many(&memcg->css, nr_pages);
}
#endif /* CONFIG_MEMCG_KMEM */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
* Because tail pages are not marked as "used", set it. We're under
* pgdat->lru_lock and migration entries setup in all page mappings.
*/
void mem_cgroup_split_huge_fixup(struct page *head)
{
int i;
if (mem_cgroup_disabled())
return;
for (i = 1; i < HPAGE_PMD_NR; i++)
head[i].mem_cgroup = head->mem_cgroup;
__mod_memcg_state(head->mem_cgroup, MEMCG_RSS_HUGE, -HPAGE_PMD_NR);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#ifdef CONFIG_MEMCG_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 >= 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)) {
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;
unsigned long nr_scanned;
if (order > 0)
return 0;
mctz = soft_limit_tree_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;
nr_scanned = 0;
reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
gfp_mask, &nr_scanned);
nr_reclaimed += reclaimed;
*total_scanned += nr_scanned;
spin_lock_irq(&mctz->lock);
__mem_cgroup_remove_exceeded(mz, mctz);
/*
* 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;
}
/*
* Test whether @memcg has children, dead or alive. Note that this
* function doesn't care whether @memcg has use_hierarchy enabled and
* returns %true if there are child csses according to the cgroup
* hierarchy. Testing use_hierarchy is the caller's responsiblity.
*/
static inline bool memcg_has_children(struct mem_cgroup *memcg)
{
bool ret;
rcu_read_lock();
ret = css_next_child(NULL, &memcg->css);
rcu_read_unlock();
return ret;
}
/*
* 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 = MEM_CGROUP_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)) {