blob: 364cf276984b7c5cf1459ab0998353951f5e85c7 [file] [log] [blame]
/* 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
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/res_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.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/page_cgroup.h>
#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/lockdep.h>
#include <linux/file.h>
#include "internal.h"
#include <net/sock.h>
#include <net/ip.h>
#include <net/tcp_memcontrol.h>
#include "slab.h"
#include <asm/uaccess.h>
#include <trace/events/vmscan.h>
struct cgroup_subsys memory_cgrp_subsys __read_mostly;
EXPORT_SYMBOL(memory_cgrp_subsys);
#define MEM_CGROUP_RECLAIM_RETRIES 5
static struct mem_cgroup *root_mem_cgroup __read_mostly;
#ifdef CONFIG_MEMCG_SWAP
/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
int do_swap_account __read_mostly;
/* for remember boot option*/
#ifdef CONFIG_MEMCG_SWAP_ENABLED
static int really_do_swap_account __initdata = 1;
#else
static int really_do_swap_account __initdata;
#endif
#else
#define do_swap_account 0
#endif
static const char * const mem_cgroup_stat_names[] = {
"cache",
"rss",
"rss_huge",
"mapped_file",
"writeback",
"swap",
};
enum mem_cgroup_events_index {
MEM_CGROUP_EVENTS_PGPGIN, /* # of pages paged in */
MEM_CGROUP_EVENTS_PGPGOUT, /* # of pages paged out */
MEM_CGROUP_EVENTS_PGFAULT, /* # of page-faults */
MEM_CGROUP_EVENTS_PGMAJFAULT, /* # of major page-faults */
MEM_CGROUP_EVENTS_NSTATS,
};
static const char * const mem_cgroup_events_names[] = {
"pgpgin",
"pgpgout",
"pgfault",
"pgmajfault",
};
static const char * const mem_cgroup_lru_names[] = {
"inactive_anon",
"active_anon",
"inactive_file",
"active_file",
"unevictable",
};
/*
* Per memcg event counter is incremented at every pagein/pageout. With THP,
* it will be incremated by the number of pages. This counter is used for
* for trigger some periodic events. This is straightforward and better
* than using jiffies etc. to handle periodic memcg event.
*/
enum mem_cgroup_events_target {
MEM_CGROUP_TARGET_THRESH,
MEM_CGROUP_TARGET_SOFTLIMIT,
MEM_CGROUP_TARGET_NUMAINFO,
MEM_CGROUP_NTARGETS,
};
#define THRESHOLDS_EVENTS_TARGET 128
#define SOFTLIMIT_EVENTS_TARGET 1024
#define NUMAINFO_EVENTS_TARGET 1024
struct mem_cgroup_stat_cpu {
long count[MEM_CGROUP_STAT_NSTATS];
unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
unsigned long nr_page_events;
unsigned long targets[MEM_CGROUP_NTARGETS];
};
struct mem_cgroup_reclaim_iter {
/*
* last scanned hierarchy member. Valid only if last_dead_count
* matches memcg->dead_count of the hierarchy root group.
*/
struct mem_cgroup *last_visited;
int last_dead_count;
/* scan generation, increased every round-trip */
unsigned int generation;
};
/*
* per-zone information in memory controller.
*/
struct mem_cgroup_per_zone {
struct lruvec lruvec;
unsigned long lru_size[NR_LRU_LISTS];
struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];
struct rb_node tree_node; /* RB tree node */
unsigned long long usage_in_excess;/* Set to the value by which */
/* the soft limit is exceeded*/
bool on_tree;
struct mem_cgroup *memcg; /* Back pointer, we cannot */
/* use container_of */
};
struct mem_cgroup_per_node {
struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
};
/*
* Cgroups above their limits are maintained in a RB-Tree, independent of
* their hierarchy representation
*/
struct mem_cgroup_tree_per_zone {
struct rb_root rb_root;
spinlock_t lock;
};
struct mem_cgroup_tree_per_node {
struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
};
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;
struct mem_cgroup_threshold {
struct eventfd_ctx *eventfd;
u64 threshold;
};
/* For threshold */
struct mem_cgroup_threshold_ary {
/* An array index points to threshold just below or equal to usage. */
int current_threshold;
/* Size of entries[] */
unsigned int size;
/* Array of thresholds */
struct mem_cgroup_threshold entries[0];
};
struct mem_cgroup_thresholds {
/* Primary thresholds array */
struct mem_cgroup_threshold_ary *primary;
/*
* Spare threshold array.
* This is needed to make mem_cgroup_unregister_event() "never fail".
* It must be able to store at least primary->size - 1 entries.
*/
struct mem_cgroup_threshold_ary *spare;
};
/* 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_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);
/*
* The memory controller data structure. The memory controller controls both
* page cache and RSS per cgroup. We would eventually like to provide
* statistics based on the statistics developed by Rik Van Riel for clock-pro,
* to help the administrator determine what knobs to tune.
*
* TODO: Add a water mark for the memory controller. Reclaim will begin when
* we hit the water mark. May be even add a low water mark, such that
* no reclaim occurs from a cgroup at it's low water mark, this is
* a feature that will be implemented much later in the future.
*/
struct mem_cgroup {
struct cgroup_subsys_state css;
/*
* the counter to account for memory usage
*/
struct res_counter res;
/* vmpressure notifications */
struct vmpressure vmpressure;
/* css_online() has been completed */
int initialized;
/*
* the counter to account for mem+swap usage.
*/
struct res_counter memsw;
/*
* the counter to account for kernel memory usage.
*/
struct res_counter kmem;
/*
* Should the accounting and control be hierarchical, per subtree?
*/
bool use_hierarchy;
unsigned long kmem_account_flags; /* See KMEM_ACCOUNTED_*, below */
bool oom_lock;
atomic_t under_oom;
atomic_t oom_wakeups;
int swappiness;
/* OOM-Killer disable */
int oom_kill_disable;
/* protect arrays of thresholds */
struct mutex thresholds_lock;
/* thresholds for memory usage. RCU-protected */
struct mem_cgroup_thresholds thresholds;
/* thresholds for mem+swap usage. RCU-protected */
struct mem_cgroup_thresholds memsw_thresholds;
/* For oom notifier event fd */
struct list_head oom_notify;
/*
* Should we move charges of a task when a task is moved into this
* mem_cgroup ? And what type of charges should we move ?
*/
unsigned long move_charge_at_immigrate;
/*
* set > 0 if pages under this cgroup are moving to other cgroup.
*/
atomic_t moving_account;
/* taken only while moving_account > 0 */
spinlock_t move_lock;
/*
* percpu counter.
*/
struct mem_cgroup_stat_cpu __percpu *stat;
/*
* used when a cpu is offlined or other synchronizations
* See mem_cgroup_read_stat().
*/
struct mem_cgroup_stat_cpu nocpu_base;
spinlock_t pcp_counter_lock;
atomic_t dead_count;
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
struct cg_proto tcp_mem;
#endif
#if defined(CONFIG_MEMCG_KMEM)
/* analogous to slab_common's slab_caches list, but per-memcg;
* protected by memcg_slab_mutex */
struct list_head memcg_slab_caches;
/* Index in the kmem_cache->memcg_params->memcg_caches array */
int kmemcg_id;
#endif
int last_scanned_node;
#if MAX_NUMNODES > 1
nodemask_t scan_nodes;
atomic_t numainfo_events;
atomic_t numainfo_updating;
#endif
/* List of events which userspace want to receive */
struct list_head event_list;
spinlock_t event_list_lock;
struct mem_cgroup_per_node *nodeinfo[0];
/* WARNING: nodeinfo must be the last member here */
};
/* internal only representation about the status of kmem accounting. */
enum {
KMEM_ACCOUNTED_ACTIVE, /* accounted by this cgroup itself */
KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */
};
#ifdef CONFIG_MEMCG_KMEM
static inline void memcg_kmem_set_active(struct mem_cgroup *memcg)
{
set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}
static bool memcg_kmem_is_active(struct mem_cgroup *memcg)
{
return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}
static void memcg_kmem_mark_dead(struct mem_cgroup *memcg)
{
/*
* Our caller must use css_get() first, because memcg_uncharge_kmem()
* will call css_put() if it sees the memcg is dead.
*/
smp_wmb();
if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags))
set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags);
}
static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg)
{
return test_and_clear_bit(KMEM_ACCOUNTED_DEAD,
&memcg->kmem_account_flags);
}
#endif
/* Stuffs for move charges at task migration. */
/*
* Types of charges to be moved. "move_charge_at_immitgrate" and
* "immigrate_flags" are treated as a left-shifted bitmap of these types.
*/
enum move_type {
MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
MOVE_CHARGE_TYPE_FILE, /* file page(including tmpfs) and swap of it */
NR_MOVE_TYPE,
};
/* "mc" and its members are protected by cgroup_mutex */
static struct move_charge_struct {
spinlock_t lock; /* for from, to */
struct mem_cgroup *from;
struct mem_cgroup *to;
unsigned long immigrate_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),
};
static bool move_anon(void)
{
return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags);
}
static bool move_file(void)
{
return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags);
}
/*
* 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,
};
#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)
/*
* The memcg_create_mutex will be held whenever a new cgroup is created.
* As a consequence, any change that needs to protect against new child cgroups
* appearing has to hold it as well.
*/
static DEFINE_MUTEX(memcg_create_mutex);
struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
{
return s ? container_of(s, struct mem_cgroup, css) : NULL;
}
/* 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;
}
static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
{
return (memcg == root_mem_cgroup);
}
/*
* We restrict the id in the range of [1, 65535], so it can fit into
* an unsigned short.
*/
#define MEM_CGROUP_ID_MAX USHRT_MAX
static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
{
return memcg->css.id;
}
static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
struct cgroup_subsys_state *css;
css = css_from_id(id, &memory_cgrp_subsys);
return mem_cgroup_from_css(css);
}
/* Writing them here to avoid exposing memcg's inner layout */
#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
void sock_update_memcg(struct sock *sk)
{
if (mem_cgroup_sockets_enabled) {
struct mem_cgroup *memcg;
struct cg_proto *cg_proto;
BUG_ON(!sk->sk_prot->proto_cgroup);
/* Socket cloning can throw us here with sk_cgrp already
* filled. It won't however, necessarily happen from
* process context. So the test for root memcg given
* the current task's memcg won't help us in this case.
*
* Respecting the original socket's memcg is a better
* decision in this case.
*/
if (sk->sk_cgrp) {
BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
css_get(&sk->sk_cgrp->memcg->css);
return;
}
rcu_read_lock();
memcg = mem_cgroup_from_task(current);
cg_proto = sk->sk_prot->proto_cgroup(memcg);
if (!mem_cgroup_is_root(memcg) &&
memcg_proto_active(cg_proto) &&
css_tryget_online(&memcg->css)) {
sk->sk_cgrp = cg_proto;
}
rcu_read_unlock();
}
}
EXPORT_SYMBOL(sock_update_memcg);
void sock_release_memcg(struct sock *sk)
{
if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
struct mem_cgroup *memcg;
WARN_ON(!sk->sk_cgrp->memcg);
memcg = sk->sk_cgrp->memcg;
css_put(&sk->sk_cgrp->memcg->css);
}
}
struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
{
if (!memcg || mem_cgroup_is_root(memcg))
return NULL;
return &memcg->tcp_mem;
}
EXPORT_SYMBOL(tcp_proto_cgroup);
static void disarm_sock_keys(struct mem_cgroup *memcg)
{
if (!memcg_proto_activated(&memcg->tcp_mem))
return;
static_key_slow_dec(&memcg_socket_limit_enabled);
}
#else
static void disarm_sock_keys(struct mem_cgroup *memcg)
{
}
#endif
#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_limited_groups_array_size. It will double each time we have to
* increase it.
*/
static DEFINE_IDA(kmem_limited_groups);
int memcg_limited_groups_array_size;
/*
* 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
*/
struct static_key memcg_kmem_enabled_key;
EXPORT_SYMBOL(memcg_kmem_enabled_key);
static void memcg_free_cache_id(int id);
static void disarm_kmem_keys(struct mem_cgroup *memcg)
{
if (memcg_kmem_is_active(memcg)) {
static_key_slow_dec(&memcg_kmem_enabled_key);
memcg_free_cache_id(memcg->kmemcg_id);
}
/*
* This check can't live in kmem destruction function,
* since the charges will outlive the cgroup
*/
WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0);
}
#else
static void disarm_kmem_keys(struct mem_cgroup *memcg)
{
}
#endif /* CONFIG_MEMCG_KMEM */
static void disarm_static_keys(struct mem_cgroup *memcg)
{
disarm_sock_keys(memcg);
disarm_kmem_keys(memcg);
}
static void drain_all_stock_async(struct mem_cgroup *memcg);
static struct mem_cgroup_per_zone *
mem_cgroup_zone_zoneinfo(struct mem_cgroup *memcg, struct zone *zone)
{
int nid = zone_to_nid(zone);
int zid = zone_idx(zone);
return &memcg->nodeinfo[nid]->zoneinfo[zid];
}
struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
{
return &memcg->css;
}
static struct mem_cgroup_per_zone *
mem_cgroup_page_zoneinfo(struct mem_cgroup *memcg, struct page *page)
{
int nid = page_to_nid(page);
int zid = page_zonenum(page);
return &memcg->nodeinfo[nid]->zoneinfo[zid];
}
static struct mem_cgroup_tree_per_zone *
soft_limit_tree_node_zone(int nid, int zid)
{
return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
}
static struct mem_cgroup_tree_per_zone *
soft_limit_tree_from_page(struct page *page)
{
int nid = page_to_nid(page);
int zid = page_zonenum(page);
return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
}
static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz,
unsigned long long new_usage_in_excess)
{
struct rb_node **p = &mctz->rb_root.rb_node;
struct rb_node *parent = NULL;
struct mem_cgroup_per_zone *mz_node;
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_zone,
tree_node);
if (mz->usage_in_excess < mz_node->usage_in_excess)
p = &(*p)->rb_left;
/*
* 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;
}
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_zone *mz,
struct mem_cgroup_tree_per_zone *mctz)
{
if (!mz->on_tree)
return;
rb_erase(&mz->tree_node, &mctz->rb_root);
mz->on_tree = false;
}
static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz)
{
unsigned long flags;
spin_lock_irqsave(&mctz->lock, flags);
__mem_cgroup_remove_exceeded(mz, mctz);
spin_unlock_irqrestore(&mctz->lock, flags);
}
static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
{
unsigned long long excess;
struct mem_cgroup_per_zone *mz;
struct mem_cgroup_tree_per_zone *mctz;
mctz = soft_limit_tree_from_page(page);
/*
* 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_zoneinfo(memcg, page);
excess = res_counter_soft_limit_excess(&memcg->res);
/*
* 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_zone *mctz;
struct mem_cgroup_per_zone *mz;
int nid, zid;
for_each_node(nid) {
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
mctz = soft_limit_tree_node_zone(nid, zid);
mem_cgroup_remove_exceeded(mz, mctz);
}
}
}
static struct mem_cgroup_per_zone *
__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
{
struct rb_node *rightmost = NULL;
struct mem_cgroup_per_zone *mz;
retry:
mz = NULL;
rightmost = rb_last(&mctz->rb_root);
if (!rightmost)
goto done; /* Nothing to reclaim from */
mz = rb_entry(rightmost, struct mem_cgroup_per_zone, 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 (!res_counter_soft_limit_excess(&mz->memcg->res) ||
!css_tryget_online(&mz->memcg->css))
goto retry;
done:
return mz;
}
static struct mem_cgroup_per_zone *
mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
{
struct mem_cgroup_per_zone *mz;
spin_lock_irq(&mctz->lock);
mz = __mem_cgroup_largest_soft_limit_node(mctz);
spin_unlock_irq(&mctz->lock);
return mz;
}
/*
* Implementation Note: reading percpu statistics for memcg.
*
* Both of vmstat[] and percpu_counter has threshold and do periodic
* synchronization to implement "quick" read. There are trade-off between
* reading cost and precision of value. Then, we may have a chance to implement
* a periodic synchronizion of counter in memcg's counter.
*
* But this _read() function is used for user interface now. The user accounts
* memory usage by memory cgroup and he _always_ requires exact value because
* he accounts memory. Even if we provide quick-and-fuzzy read, we always
* have to visit all online cpus and make sum. So, for now, unnecessary
* synchronization is not implemented. (just implemented for cpu hotplug)
*
* If there are kernel internal actions which can make use of some not-exact
* value, and reading all cpu value can be performance bottleneck in some
* common workload, threashold and synchonization as vmstat[] should be
* implemented.
*/
static long mem_cgroup_read_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx)
{
long val = 0;
int cpu;
get_online_cpus();
for_each_online_cpu(cpu)
val += per_cpu(memcg->stat->count[idx], cpu);
#ifdef CONFIG_HOTPLUG_CPU
spin_lock(&memcg->pcp_counter_lock);
val += memcg->nocpu_base.count[idx];
spin_unlock(&memcg->pcp_counter_lock);
#endif
put_online_cpus();
return val;
}
static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
enum mem_cgroup_events_index idx)
{
unsigned long val = 0;
int cpu;
get_online_cpus();
for_each_online_cpu(cpu)
val += per_cpu(memcg->stat->events[idx], cpu);
#ifdef CONFIG_HOTPLUG_CPU
spin_lock(&memcg->pcp_counter_lock);
val += memcg->nocpu_base.events[idx];
spin_unlock(&memcg->pcp_counter_lock);
#endif
put_online_cpus();
return val;
}
static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
struct page *page,
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))
__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
nr_pages);
else
__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
nr_pages);
if (PageTransHuge(page))
__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
nr_pages);
/* pagein of a big page is an event. So, ignore page size */
if (nr_pages > 0)
__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
else {
__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
nr_pages = -nr_pages; /* for event */
}
__this_cpu_add(memcg->stat->nr_page_events, nr_pages);
}
unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
{
struct mem_cgroup_per_zone *mz;
mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
return mz->lru_size[lru];
}
static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
int nid,
unsigned int lru_mask)
{
unsigned long nr = 0;
int zid;
VM_BUG_ON((unsigned)nid >= nr_node_ids);
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
struct mem_cgroup_per_zone *mz;
enum lru_list lru;
for_each_lru(lru) {
if (!(BIT(lru) & lru_mask))
continue;
mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
nr += mz->lru_size[lru];
}
}
return nr;
}
static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
unsigned int lru_mask)
{
unsigned long nr = 0;
int nid;
for_each_node_state(nid, N_MEMORY)
nr += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
return nr;
}
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->stat->nr_page_events);
next = __this_cpu_read(memcg->stat->targets[target]);
/* from time_after() in jiffies.h */
if ((long)next - (long)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->stat->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));
}
static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
{
struct mem_cgroup *memcg = 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;
}
/*
* Returns a next (in a pre-order walk) alive memcg (with elevated css
* ref. count) or NULL if the whole root's subtree has been visited.
*
* helper function to be used by mem_cgroup_iter
*/
static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root,
struct mem_cgroup *last_visited)
{
struct cgroup_subsys_state *prev_css, *next_css;
prev_css = last_visited ? &last_visited->css : NULL;
skip_node:
next_css = css_next_descendant_pre(prev_css, &root->css);
/*
* Even if we found a group we have to make sure it is
* alive. css && !memcg means that the groups should be
* skipped and we should continue the tree walk.
* last_visited css is safe to use because it is
* protected by css_get and the tree walk is rcu safe.
*
* We do not take a reference on the root of the tree walk
* because we might race with the root removal when it would
* be the only node in the iterated hierarchy and mem_cgroup_iter
* would end up in an endless loop because it expects that at
* least one valid node will be returned. Root cannot disappear
* because caller of the iterator should hold it already so
* skipping css reference should be safe.
*/
if (next_css) {
struct mem_cgroup *memcg = mem_cgroup_from_css(next_css);
if (next_css == &root->css)
return memcg;
if (css_tryget_online(next_css)) {
/*
* Make sure the memcg is initialized:
* mem_cgroup_css_online() orders the the
* initialization against setting the flag.
*/
if (smp_load_acquire(&memcg->initialized))
return memcg;
css_put(next_css);
}
prev_css = next_css;
goto skip_node;
}
return NULL;
}
static void mem_cgroup_iter_invalidate(struct mem_cgroup *root)
{
/*
* When a group in the hierarchy below root is destroyed, the
* hierarchy iterator can no longer be trusted since it might
* have pointed to the destroyed group. Invalidate it.
*/
atomic_inc(&root->dead_count);
}
static struct mem_cgroup *
mem_cgroup_iter_load(struct mem_cgroup_reclaim_iter *iter,
struct mem_cgroup *root,
int *sequence)
{
struct mem_cgroup *position = NULL;
/*
* A cgroup destruction happens in two stages: offlining and
* release. They are separated by a RCU grace period.
*
* If the iterator is valid, we may still race with an
* offlining. The RCU lock ensures the object won't be
* released, tryget will fail if we lost the race.
*/
*sequence = atomic_read(&root->dead_count);
if (iter->last_dead_count == *sequence) {
smp_rmb();
position = iter->last_visited;
/*
* We cannot take a reference to root because we might race
* with root removal and returning NULL would end up in
* an endless loop on the iterator user level when root
* would be returned all the time.
*/
if (position && position != root &&
!css_tryget_online(&position->css))
position = NULL;
}
return position;
}
static void mem_cgroup_iter_update(struct mem_cgroup_reclaim_iter *iter,
struct mem_cgroup *last_visited,
struct mem_cgroup *new_position,
struct mem_cgroup *root,
int sequence)
{
/* root reference counting symmetric to mem_cgroup_iter_load */
if (last_visited && last_visited != root)
css_put(&last_visited->css);
/*
* We store the sequence count from the time @last_visited was
* loaded successfully instead of rereading it here so that we
* don't lose destruction events in between. We could have
* raced with the destruction of @new_position after all.
*/
iter->last_visited = new_position;
smp_wmb();
iter->last_dead_count = sequence;
}
/**
* 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 zone and a priority level in @reclaim to
* divide up the memcgs in the hierarchy among all concurrent
* reclaimers operating on the same zone 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 *memcg = NULL;
struct mem_cgroup *last_visited = NULL;
if (mem_cgroup_disabled())
return NULL;
if (!root)
root = root_mem_cgroup;
if (prev && !reclaim)
last_visited = prev;
if (!root->use_hierarchy && root != root_mem_cgroup) {
if (prev)
goto out_css_put;
return root;
}
rcu_read_lock();
while (!memcg) {
struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
int uninitialized_var(seq);
if (reclaim) {
struct mem_cgroup_per_zone *mz;
mz = mem_cgroup_zone_zoneinfo(root, reclaim->zone);
iter = &mz->reclaim_iter[reclaim->priority];
if (prev && reclaim->generation != iter->generation) {
iter->last_visited = NULL;
goto out_unlock;
}
last_visited = mem_cgroup_iter_load(iter, root, &seq);
}
memcg = __mem_cgroup_iter_next(root, last_visited);
if (reclaim) {
mem_cgroup_iter_update(iter, last_visited, memcg, root,
seq);
if (!memcg)
iter->generation++;
else if (!prev && memcg)
reclaim->generation = iter->generation;
}
if (prev && !memcg)
goto out_unlock;
}
out_unlock:
rcu_read_unlock();
out_css_put:
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);
}
/*
* 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))
void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
{
struct mem_cgroup *memcg;
rcu_read_lock();
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))
goto out;
switch (idx) {
case PGFAULT:
this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
break;
case PGMAJFAULT:
this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
break;
default:
BUG();
}
out:
rcu_read_unlock();
}
EXPORT_SYMBOL(__mem_cgroup_count_vm_event);
/**
* mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
* @zone: zone of the wanted lruvec
* @memcg: memcg of the wanted lruvec
*
* Returns the lru list vector holding pages for the given @zone and
* @mem. This can be the global zone lruvec, if the memory controller
* is disabled.
*/
struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
struct mem_cgroup *memcg)
{
struct mem_cgroup_per_zone *mz;
struct lruvec *lruvec;
if (mem_cgroup_disabled()) {
lruvec = &zone->lruvec;
goto out;
}
mz = mem_cgroup_zone_zoneinfo(memcg, zone);
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->zone != zone))
lruvec->zone = zone;
return lruvec;
}
/**
* mem_cgroup_page_lruvec - return lruvec for adding an lru page
* @page: the page
* @zone: zone of the page
*/
struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
{
struct mem_cgroup_per_zone *mz;
struct mem_cgroup *memcg;
struct page_cgroup *pc;
struct lruvec *lruvec;
if (mem_cgroup_disabled()) {
lruvec = &zone->lruvec;
goto out;
}
pc = lookup_page_cgroup(page);
memcg = pc->mem_cgroup;
/*
* Surreptitiously switch any uncharged offlist page to root:
* an uncharged page off lru does nothing to secure
* its former mem_cgroup from sudden removal.
*
* Our caller holds lru_lock, and PageCgroupUsed is updated
* under page_cgroup lock: between them, they make all uses
* of pc->mem_cgroup safe.
*/
if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup)
pc->mem_cgroup = memcg = root_mem_cgroup;
mz = mem_cgroup_page_zoneinfo(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->zone != zone))
lruvec->zone = zone;
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
* @nr_pages: positive when adding or negative when removing
*
* This function must be called when a page is added to or removed from an
* lru list.
*/
void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
int nr_pages)
{
struct mem_cgroup_per_zone *mz;
unsigned long *lru_size;
if (mem_cgroup_disabled())
return;
mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
lru_size = mz->lru_size + lru;
*lru_size += nr_pages;
VM_BUG_ON((long)(*lru_size) < 0);
}
/*
* Checks whether given mem is same or in the root_mem_cgroup's
* hierarchy subtree
*/
bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
struct mem_cgroup *memcg)
{
if (root_memcg == memcg)
return true;
if (!root_memcg->use_hierarchy || !memcg)
return false;
return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
}
static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
struct mem_cgroup *memcg)
{
bool ret;
rcu_read_lock();
ret = __mem_cgroup_same_or_subtree(root_memcg, memcg);
rcu_read_unlock();
return ret;
}
bool task_in_mem_cgroup(struct task_struct *task,
const struct mem_cgroup *memcg)
{
struct mem_cgroup *curr = NULL;
struct task_struct *p;
bool ret;
p = find_lock_task_mm(task);
if (p) {
curr = 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();
curr = mem_cgroup_from_task(task);
if (curr)
css_get(&curr->css);
rcu_read_unlock();
}
/*
* We should check use_hierarchy of "memcg" not "curr". Because checking
* use_hierarchy of "curr" here make this function true if hierarchy is
* enabled in "curr" and "curr" is a child of "memcg" in *cgroup*
* hierarchy(even if use_hierarchy is disabled in "memcg").
*/
ret = mem_cgroup_same_or_subtree(memcg, curr);
css_put(&curr->css);
return ret;
}
int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
{
unsigned long inactive_ratio;
unsigned long inactive;
unsigned long active;
unsigned long gb;
inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);
gb = (inactive + active) >> (30 - PAGE_SHIFT);
if (gb)
inactive_ratio = int_sqrt(10 * gb);
else
inactive_ratio = 1;
return inactive * inactive_ratio < active;
}
#define mem_cgroup_from_res_counter(counter, member) \
container_of(counter, struct mem_cgroup, member)
/**
* 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 long margin;
margin = res_counter_margin(&memcg->res);
if (do_swap_account)
margin = min(margin, res_counter_margin(&memcg->memsw));
return margin >> PAGE_SHIFT;
}
int mem_cgroup_swappiness(struct mem_cgroup *memcg)
{
/* root ? */
if (mem_cgroup_disabled() || !memcg->css.parent)
return vm_swappiness;
return memcg->swappiness;
}
/*
* memcg->moving_account is used for checking possibility that some thread is
* calling move_account(). When a thread on CPU-A starts moving pages under
* a memcg, other threads should check memcg->moving_account under
* rcu_read_lock(), like this:
*
* CPU-A CPU-B
* rcu_read_lock()
* memcg->moving_account+1 if (memcg->mocing_account)
* take heavy locks.
* synchronize_rcu() update something.
* rcu_read_unlock()
* start move here.
*/
static void mem_cgroup_start_move(struct mem_cgroup *memcg)
{
atomic_inc(&memcg->moving_account);
synchronize_rcu();
}
static void mem_cgroup_end_move(struct mem_cgroup *memcg)
{
/*
* Now, mem_cgroup_clear_mc() may call this function with NULL.
* We check NULL in callee rather than caller.
*/
if (memcg)
atomic_dec(&memcg->moving_account);
}
/*
* 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_same_or_subtree(memcg, from)
|| mem_cgroup_same_or_subtree(memcg, to);
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;
}
/*
* Take this lock when
* - a code tries to modify page's memcg while it's USED.
* - a code tries to modify page state accounting in a memcg.
*/
static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
unsigned long *flags)
{
spin_lock_irqsave(&memcg->move_lock, *flags);
}
static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
unsigned long *flags)
{
spin_unlock_irqrestore(&memcg->move_lock, *flags);
}
#define K(x) ((x) << (PAGE_SHIFT-10))
/**
* mem_cgroup_print_oom_info: 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_info(struct mem_cgroup *memcg, struct task_struct *p)
{
/* oom_info_lock ensures that parallel ooms do not interleave */
static DEFINE_MUTEX(oom_info_lock);
struct mem_cgroup *iter;
unsigned int i;
if (!p)
return;
mutex_lock(&oom_info_lock);
rcu_read_lock();
pr_info("Task in ");
pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
pr_info(" killed as a result of limit of ");
pr_cont_cgroup_path(memcg->css.cgroup);
pr_info("\n");
rcu_read_unlock();
pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n",
res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
res_counter_read_u64(&memcg->res, RES_FAILCNT));
pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %llu\n",
res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
pr_info("kmem: usage %llukB, limit %llukB, failcnt %llu\n",
res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
res_counter_read_u64(&memcg->kmem, RES_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 < MEM_CGROUP_STAT_NSTATS; i++) {
if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
continue;
pr_cont(" %s:%ldKB", mem_cgroup_stat_names[i],
K(mem_cgroup_read_stat(iter, i)));
}
for (i = 0; i < NR_LRU_LISTS; i++)
pr_cont(" %s:%luKB", mem_cgroup_lru_names[i],
K(mem_cgroup_nr_lru_pages(iter, BIT(i))));
pr_cont("\n");
}
mutex_unlock(&oom_info_lock);
}
/*
* This function returns the number of memcg under hierarchy tree. Returns
* 1(self count) if no children.
*/
static int mem_cgroup_count_children(struct mem_cgroup *memcg)
{
int num = 0;
struct mem_cgroup *iter;
for_each_mem_cgroup_tree(iter, memcg)
num++;
return num;
}
/*
* Return the memory (and swap, if configured) limit for a memcg.
*/
static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
{
u64 limit;
limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
/*
* Do not consider swap space if we cannot swap due to swappiness
*/
if (mem_cgroup_swappiness(memcg)) {
u64 memsw;
limit += total_swap_pages << PAGE_SHIFT;
memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
/*
* If memsw is finite and limits the amount of swap space
* available to this memcg, return that limit.
*/
limit = min(limit, memsw);
}
return limit;
}
static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
int order)
{
struct mem_cgroup *iter;
unsigned long chosen_points = 0;
unsigned long totalpages;
unsigned int points = 0;
struct task_struct *chosen = NULL;
/*
* If current has a pending SIGKILL or is exiting, then automatically
* select it. The goal is to allow it to allocate so that it may
* quickly exit and free its memory.
*/
if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
set_thread_flag(TIF_MEMDIE);
return;
}
check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
for_each_mem_cgroup_tree(iter, memcg) {
struct css_task_iter it;
struct task_struct *task;
css_task_iter_start(&iter->css, &it);
while ((task = css_task_iter_next(&it))) {
switch (oom_scan_process_thread(task, totalpages, NULL,
false)) {
case OOM_SCAN_SELECT:
if (chosen)
put_task_struct(chosen);
chosen = task;
chosen_points = ULONG_MAX;
get_task_struct(chosen);
/* fall through */
case OOM_SCAN_CONTINUE:
continue;
case OOM_SCAN_ABORT:
css_task_iter_end(&it);
mem_cgroup_iter_break(memcg, iter);
if (chosen)
put_task_struct(chosen);
return;
case OOM_SCAN_OK:
break;
};
points = oom_badness(task, memcg, NULL, totalpages);
if (!points || points < chosen_points)
continue;
/* Prefer thread group leaders for display purposes */
if (points == chosen_points &&
thread_group_leader(chosen))
continue;
if (chosen)
put_task_struct(chosen);
chosen = task;
chosen_points = points;
get_task_struct(chosen);
}
css_task_iter_end(&it);
}
if (!chosen)
return;
points = chosen_points * 1000 / totalpages;
oom_kill_process(chosen, gfp_mask, order, points, totalpages, memcg,
NULL, "Memory cgroup out of memory");
}
/**
* 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)
{
if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
return true;
if (noswap || !total_swap_pages)
return false;
if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
return true;
return false;
}
#if MAX_NUMNODES > 1
/*
* 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(node, memcg->scan_nodes);
if (node == MAX_NUMNODES)
node = first_node(memcg->scan_nodes);
/*
* We call this when we hit limit, not when pages are added to LRU.
* No LRU may hold pages because all pages are UNEVICTABLE or
* memcg is too small and all pages are not on LRU. In that case,
* we use curret node.
*/
if (unlikely(node == MAX_NUMNODES))
node = numa_node_id();
memcg->last_scanned_node = node;
return node;
}
/*
* Check all nodes whether it contains reclaimable pages or not.
* For quick scan, we make use of scan_nodes. This will allow us to skip
* unused nodes. But scan_nodes is lazily updated and may not cotain
* enough new information. We need to do double check.
*/
static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
int nid;
/*
* quick check...making use of scan_node.
* We can skip unused nodes.
*/
if (!nodes_empty(memcg->scan_nodes)) {
for (nid = first_node(memcg->scan_nodes);
nid < MAX_NUMNODES;
nid = next_node(nid, memcg->scan_nodes)) {
if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
return true;
}
}
/*
* Check rest of nodes.
*/
for_each_node_state(nid, N_MEMORY) {
if (node_isset(nid, memcg->scan_nodes))
continue;
if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
return true;
}
return false;
}
#else
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
{
return 0;
}
static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
}
#endif
static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
struct zone *zone,
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 = {
.zone = zone,
.priority = 0,
};
excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
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;
}
if (!mem_cgroup_reclaimable(victim, false))
continue;
total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
zone, &nr_scanned);
*total_scanned += nr_scanned;
if (!res_counter_soft_limit_excess(&root_memcg->res))
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;
for_each_mem_cgroup_tree(iter, memcg)
atomic_inc(&iter->under_oom);
}
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. We have to use
* atomic_add_unless() here.
*/
for_each_mem_cgroup_tree(iter, memcg)
atomic_add_unless(&iter->under_oom, -1, 0);
}
static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
struct oom_wait_info {
struct mem_cgroup *memcg;
wait_queue_t wait;
};
static int memcg_oom_wake_function(wait_queue_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;
/*
* Both of oom_wait_info->memcg and wake_memcg are stable under us.
* Then we can use css_is_ancestor without taking care of RCU.
*/
if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg)
&& !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg))
return 0;
return autoremove_wake_function(wait, mode, sync, arg);
}
static void memcg_wakeup_oom(struct mem_cgroup *memcg)
{
atomic_inc(&memcg->oom_wakeups);
/* for filtering, pass "memcg" as argument. */
__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
}
static void memcg_oom_recover(struct mem_cgroup *memcg)
{
if (memcg && atomic_read(&memcg->under_oom))
memcg_wakeup_oom(memcg);
}
static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
{
if (!current->memcg_oom.may_oom)
return;
/*
* 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.
*
* Also, the caller may handle a failed allocation gracefully
* (like optional page cache readahead) and so an OOM killer
* invocation might not even be necessary.
*
* That's why we don't do anything here except remember the
* OOM context and then deal with it at the end of the page
* fault when the stack is unwound, the locks are released,
* and when we know whether the fault was overall successful.
*/
css_get(&memcg->css);
current->memcg_oom.memcg = memcg;
current->memcg_oom.gfp_mask = mask;
current->memcg_oom.order = order;
}
/**
* 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_oom.memcg;
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.task_list);
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_oom.memcg = NULL;
css_put(&memcg->css);
return true;
}
/**
* mem_cgroup_begin_page_stat - begin a page state statistics transaction
* @page: page that is going to change accounted state
* @locked: &memcg->move_lock slowpath was taken
* @flags: IRQ-state flags for &memcg->move_lock
*
* This function must mark the beginning of an accounted page state
* change to prevent double accounting when the page is concurrently
* being moved to another memcg:
*
* memcg = mem_cgroup_begin_page_stat(page, &locked, &flags);
* if (TestClearPageState(page))
* mem_cgroup_update_page_stat(memcg, state, -1);
* mem_cgroup_end_page_stat(memcg, locked, flags);
*
* The RCU lock is held throughout the transaction. The fast path can
* get away without acquiring the memcg->move_lock (@locked is false)
* 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
* from being uncharged. E.g. end-writeback clearing PageWriteback(),
* which allows migration to go ahead and uncharge the page before the
* account transaction might be complete.
*/
struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page,
bool *locked,
unsigned long *flags)
{
struct mem_cgroup *memcg;
struct page_cgroup *pc;
rcu_read_lock();
if (mem_cgroup_disabled())
return NULL;
pc = lookup_page_cgroup(page);
again:
memcg = pc->mem_cgroup;
if (unlikely(!memcg || !PageCgroupUsed(pc)))
return NULL;
*locked = false;
if (atomic_read(&memcg->moving_account) <= 0)
return memcg;
move_lock_mem_cgroup(memcg, flags);
if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
move_unlock_mem_cgroup(memcg, flags);
goto again;
}
*locked = true;
return memcg;
}
/**
* mem_cgroup_end_page_stat - finish a page state statistics transaction
* @memcg: the memcg that was accounted against
* @locked: value received from mem_cgroup_begin_page_stat()
* @flags: value received from mem_cgroup_begin_page_stat()
*/
void mem_cgroup_end_page_stat(struct mem_cgroup *memcg, bool locked,
unsigned long flags)
{
if (memcg && locked)
move_unlock_mem_cgroup(memcg, &flags);
rcu_read_unlock();
}
/**
* mem_cgroup_update_page_stat - update page state statistics
* @memcg: memcg to account against
* @idx: page state item to account
* @val: number of pages (positive or negative)
*
* See mem_cgroup_begin_page_stat() for locking requirements.
*/
void mem_cgroup_update_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx, int val)
{
VM_BUG_ON(!rcu_read_lock_held());
if (memcg)
this_cpu_add(memcg->stat->count[idx], val);
}
/*
* size of first charge trial. "32" comes from vmscan.c's magic value.
* TODO: maybe necessary to use big numbers in big irons.
*/
#define CHARGE_BATCH 32U
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;
bool ret = true;
if (nr_pages > CHARGE_BATCH)
return false;
stock = &get_cpu_var(memcg_stock);
if (memcg == stock->cached && stock->nr_pages >= nr_pages)
stock->nr_pages -= nr_pages;
else /* need to call res_counter_charge */
ret = false;
put_cpu_var(memcg_stock);
return ret;
}
/*
* Returns stocks cached in percpu to res_counter and reset cached information.
*/
static void drain_stock(struct memcg_stock_pcp *stock)
{
struct mem_cgroup *old = stock->cached;
if (stock->nr_pages) {
unsigned long bytes = stock->nr_pages * PAGE_SIZE;
res_counter_uncharge(&old->res, bytes);
if (do_swap_account)
res_counter_uncharge(&old->memsw, bytes);
stock->nr_pages = 0;
}
stock->cached = NULL;
}
/*
* This must be called under preempt disabled or must be called by
* a thread which is pinned to local cpu.
*/
static void drain_local_stock(struct work_struct *dummy)
{
struct memcg_stock_pcp *stock = this_cpu_ptr(&memcg_stock);
drain_stock(stock);
clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
}
static void __init memcg_stock_init(void)
{
int cpu;
for_each_possible_cpu(cpu) {
struct memcg_stock_pcp *stock =
&per_cpu(memcg_stock, cpu);
INIT_WORK(&stock->work, drain_local_stock);
}
}
/*
* Cache charges(val) which is from res_counter, 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 = &get_cpu_var(memcg_stock);
if (stock->cached != memcg) { /* reset if necessary */
drain_stock(stock);
stock->cached = memcg;
}
stock->nr_pages += nr_pages;
put_cpu_var(memcg_stock);
}
/*
* Drains all per-CPU charge caches for given root_memcg resp. subtree
* of the hierarchy under it. sync flag says whether we should block
* until the work is done.
*/
static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
{
int cpu, curcpu;
/* Notify other cpus that system-wide "drain" is running */
get_online_cpus();
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)
continue;
if (!mem_cgroup_same_or_subtree(root_memcg, memcg))
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);
}
}
put_cpu();
if (!sync)
goto out;
for_each_online_cpu(cpu) {
struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
flush_work(&stock->work);
}
out:
put_online_cpus();
}
/*
* Tries to drain stocked charges in other cpus. This function is asynchronous
* and just put a work per cpu for draining localy on each cpu. Caller can
* expects some charges will be back to res_counter later but cannot wait for
* it.
*/
static void drain_all_stock_async(struct mem_cgroup *root_memcg)
{
/*
* If someone calls draining, avoid adding more kworker runs.
*/
if (!mutex_trylock(&percpu_charge_mutex))
return;
drain_all_stock(root_memcg, false);
mutex_unlock(&percpu_charge_mutex);
}
/* This is a synchronous drain interface. */
static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
{
/* called when force_empty is called */
mutex_lock(&percpu_charge_mutex);
drain_all_stock(root_memcg, true);
mutex_unlock(&percpu_charge_mutex);
}
/*
* This function drains percpu counter value from DEAD cpu and
* move it to local cpu. Note that this function can be preempted.
*/
static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu)
{
int i;
spin_lock(&memcg->pcp_counter_lock);
for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
long x = per_cpu(memcg->stat->count[i], cpu);
per_cpu(memcg->stat->count[i], cpu) = 0;
memcg->nocpu_base.count[i] += x;
}
for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
unsigned long x = per_cpu(memcg->stat->events[i], cpu);
per_cpu(memcg->stat->events[i], cpu) = 0;
memcg->nocpu_base.events[i] += x;
}
spin_unlock(&memcg->pcp_counter_lock);
}
static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
unsigned long action,
void *hcpu)
{
int cpu = (unsigned long)hcpu;
struct memcg_stock_pcp *stock;
struct mem_cgroup *iter;
if (action == CPU_ONLINE)
return NOTIFY_OK;
if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
return NOTIFY_OK;
for_each_mem_cgroup(iter)
mem_cgroup_drain_pcp_counter(iter, cpu);
stock = &per_cpu(memcg_stock, cpu);
drain_stock(stock);
return NOTIFY_OK;
}
static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
unsigned int nr_pages)
{
unsigned int batch = max(CHARGE_BATCH, nr_pages);
int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
struct mem_cgroup *mem_over_limit;
struct res_counter *fail_res;
unsigned long nr_reclaimed;
unsigned long long size;
bool may_swap = true;
bool drained = false;
int ret = 0;
if (mem_cgroup_is_root(memcg))
goto done;
retry:
if (consume_stock(memcg, nr_pages))
goto done;
size = batch * PAGE_SIZE;
if (!do_swap_account ||
!res_counter_charge(&memcg->memsw, size, &fail_res)) {
if (!res_counter_charge(&memcg->res, size, &fail_res))
goto done_restock;
if (do_swap_account)
res_counter_uncharge(&memcg->memsw, size);
mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
} else {
mem_over_limit = mem_cgroup_from_res_counter(fail_res, 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(test_thread_flag(TIF_MEMDIE) ||
fatal_signal_pending(current) ||
current->flags & PF_EXITING))
goto bypass;
if (unlikely(task_in_memcg_oom(current)))
goto nomem;
if (!(gfp_mask & __GFP_WAIT))
goto nomem;
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_async(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_NOFAIL)
goto bypass;
if (fatal_signal_pending(current))
goto bypass;
mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(nr_pages));
nomem:
if (!(gfp_mask & __GFP_NOFAIL))
return -ENOMEM;
bypass:
return -EINTR;
done_restock:
if (batch > nr_pages)
refill_stock(memcg, batch - nr_pages);
done:
return ret;
}
static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
{
unsigned long bytes = nr_pages * PAGE_SIZE;
if (mem_cgroup_is_root(memcg))
return;
res_counter_uncharge(&memcg->res, bytes);
if (do_swap_account)
res_counter_uncharge(&memcg->memsw, bytes);
}
/*
* Cancel chrages in this cgroup....doesn't propagate to parent cgroup.
* This is useful when moving usage to parent cgroup.
*/
static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
unsigned int nr_pages)
{
unsigned long bytes = nr_pages * PAGE_SIZE;
if (mem_cgroup_is_root(memcg))
return;
res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
if (do_swap_account)
res_counter_uncharge_until(&memcg->memsw,
memcg->memsw.parent, bytes);
}
/*
* A helper function to get mem_cgroup from ID. must be called under
* rcu_read_lock(). The caller is responsible for calling
* css_tryget_online() if the mem_cgroup is used for charging. (dropping
* refcnt from swap can be called against removed memcg.)
*/
static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
{
/* ID 0 is unused ID */
if (!id)
return NULL;
return mem_cgroup_from_id(id);
}
/*
* try_get_mem_cgroup_from_page - look up page's memcg association
* @page: the page
*
* Look up, get a css reference, and return the memcg that owns @page.
*
* The page must be locked to prevent racing with swap-in and page
* cache charges. If coming from an unlocked page table, the caller
* must ensure the page is on the LRU or this can race with charging.
*/
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
{
struct mem_cgroup *memcg = NULL;
struct page_cgroup *pc;
unsigned short id;
swp_entry_t ent;
VM_BUG_ON_PAGE(!PageLocked(page), page);
pc = lookup_page_cgroup(page);
if (PageCgroupUsed(pc)) {
memcg = pc->mem_cgroup;
if (memcg && !css_tryget_online(&memcg->css))
memcg = NULL;
} else if (PageSwapCache(page)) {
ent.val = page_private(page);
id = lookup_swap_cgroup_id(ent);
rcu_read_lock();
memcg = mem_cgroup_lookup(id);
if (memcg && !css_tryget_online(&memcg->css))
memcg = NULL;
rcu_read_unlock();
}
return memcg;
}
static void lock_page_lru(struct page *page, int *isolated)
{
struct zone *zone = page_zone(page);
spin_lock_irq(&zone->lru_lock);
if (PageLRU(page)) {
struct lruvec *lruvec;
lruvec = mem_cgroup_page_lruvec(page, zone);
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)
{
struct zone *zone = page_zone(page);
if (isolated) {
struct lruvec *lruvec;
lruvec = mem_cgroup_page_lruvec(page, zone);
VM_BUG_ON_PAGE(PageLRU(page), page);
SetPageLRU(page);
add_page_to_lru_list(page, lruvec, page_lru(page));
}
spin_unlock_irq(&zone->lru_lock);
}
static void commit_charge(struct page *page, struct mem_cgroup *memcg,
bool lrucare)
{
struct page_cgroup *pc = lookup_page_cgroup(page);
int isolated;
VM_BUG_ON_PAGE(PageCgroupUsed(pc), page);
/*
* we don't need page_cgroup_lock about tail pages, becase they are not
* accessed by any other context at this point.
*/
/*
* 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
* pc->mem_cgroup and pc->flags 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
*/
pc->mem_cgroup = memcg;
pc->flags = PCG_USED | PCG_MEM | (do_swap_account ? PCG_MEMSW : 0);
if (lrucare)
unlock_page_lru(page, isolated);
}
static DEFINE_MUTEX(set_limit_mutex);
#ifdef CONFIG_MEMCG_KMEM
/*
* The memcg_slab_mutex is held whenever a per memcg kmem cache is created or
* destroyed. It protects memcg_caches arrays and memcg_slab_caches lists.
*/
static DEFINE_MUTEX(memcg_slab_mutex);
static DEFINE_MUTEX(activate_kmem_mutex);
/*
* This is a bit cumbersome, but it is rarely used and avoids a backpointer
* in the memcg_cache_params struct.
*/
static struct kmem_cache *memcg_params_to_cache(struct memcg_cache_params *p)
{
struct kmem_cache *cachep;
VM_BUG_ON(p->is_root_cache);
cachep = p->root_cache;
return cache_from_memcg_idx(cachep, memcg_cache_id(p->memcg));
}
#ifdef CONFIG_SLABINFO
static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
struct memcg_cache_params *params;
if (!memcg_kmem_is_active(memcg))
return -EIO;
print_slabinfo_header(m);
mutex_lock(&memcg_slab_mutex);
list_for_each_entry(params, &memcg->memcg_slab_caches, list)
cache_show(memcg_params_to_cache(params), m);
mutex_unlock(&memcg_slab_mutex);
return 0;
}
#endif
static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
{
struct res_counter *fail_res;
int ret = 0;
ret = res_counter_charge(&memcg->kmem, size, &fail_res);
if (ret)
return ret;
ret = try_charge(memcg, gfp, size >> PAGE_SHIFT);
if (ret == -EINTR) {
/*
* try_charge() chose to bypass to root due to OOM kill or
* fatal signal. Since our only options are to either fail
* the allocation or charge it to this cgroup, do it as a
* temporary condition. But we can't fail. From a kmem/slab
* perspective, the cache has already been selected, by
* mem_cgroup_kmem_get_cache(), so it is too late to change
* our minds.
*
* This condition will only trigger if the task entered
* memcg_charge_kmem in a sane state, but was OOM-killed
* during try_charge() above. Tasks that were already dying
* when the allocation triggers should have been already
* directed to the root cgroup in memcontrol.h
*/
res_counter_charge_nofail(&memcg->res, size, &fail_res);
if (do_swap_account)
res_counter_charge_nofail(&memcg->memsw, size,
&fail_res);
ret = 0;
} else if (ret)
res_counter_uncharge(&memcg->kmem, size);
return ret;
}
static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
{
res_counter_uncharge(&memcg->res, size);
if (do_swap_account)
res_counter_uncharge(&memcg->memsw, size);
/* Not down to 0 */
if (res_counter_uncharge(&memcg->kmem, size))
return;
/*
* Releases a reference taken in kmem_cgroup_css_offline in case
* this last uncharge is racing with the offlining code or it is
* outliving the memcg existence.
*
* The memory barrier imposed by test&clear is paired with the
* explicit one in memcg_kmem_mark_dead().
*/
if (memcg_kmem_test_and_clear_dead(memcg))
css_put(&memcg->css);
}
/*
* helper for acessing a memcg's index. It will be used as an index in the
* child cache array in kmem_cache, and also to derive its name. This function
* will return -1 when this is not a kmem-limited memcg.
*/
int memcg_cache_id(struct mem_cgroup *memcg)
{
return memcg ? memcg->kmemcg_id : -1;
}
static int memcg_alloc_cache_id(void)
{
int id, size;
int err;
id = ida_simple_get(&kmem_limited_groups,
0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
if (id < 0)
return id;
if (id < memcg_limited_groups_array_size)
return id;
/*
* There's no space for the new id in memcg_caches arrays,
* so we have to grow them.
*/
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;
mutex_lock(&memcg_slab_mutex);
err = memcg_update_all_caches(size);
mutex_unlock(&memcg_slab_mutex);
if (err) {
ida_simple_remove(&kmem_limited_groups, id);
return err;
}
return id;
}
static void memcg_free_cache_id(int id)
{
ida_simple_remove(&kmem_limited_groups, id);
}
/*
* We should update the current array size iff all caches updates succeed. This
* can only be done from the slab side. The slab mutex needs to be held when
* calling this.
*/
void memcg_update_array_size(int num)
{
memcg_limited_groups_array_size = num;
}
static void memcg_register_cache(struct mem_cgroup *memcg,
struct kmem_cache *root_cache)
{
static char memcg_name_buf[NAME_MAX + 1]; /* protected by
memcg_slab_mutex */
struct kmem_cache *cachep;
int id;
lockdep_assert_held(&memcg_slab_mutex);
id = memcg_cache_id(memcg);
/*
* Since per-memcg caches are created asynchronously on first
* allocation (see memcg_kmem_get_cache()), several threads can try to
* create the same cache, but only one of them may succeed.
*/
if (cache_from_memcg_idx(root_cache, id))
return;
cgroup_name(memcg->css.cgroup, memcg_name_buf, NAME_MAX + 1);
cachep = memcg_create_kmem_cache(memcg, root_cache, memcg_name_buf);
/*
* If we could not create a memcg cache, do not complain, because
* that's not critical at all as we can always proceed with the root
* cache.
*/
if (!cachep)
return;
css_get(&memcg->css);
list_add(&cachep->memcg_params->list, &memcg->memcg_slab_caches);
/*
* Since readers won't lock (see cache_from_memcg_idx()), we need a
* barrier here to ensure nobody will see the kmem_cache partially
* initialized.
*/
smp_wmb();
BUG_ON(root_cache->memcg_params->memcg_caches[id]);
root_cache->memcg_params->memcg_caches[id] = cachep;
}
static void memcg_unregister_cache(struct kmem_cache *cachep)
{
struct kmem_cache *root_cache;
struct mem_cgroup *memcg;
int id;
lockdep_assert_held(&memcg_slab_mutex);
BUG_ON(is_root_cache(cachep));
root_cache = cachep->memcg_params->root_cache;
memcg = cachep->memcg_params->memcg;
id = memcg_cache_id(memcg);
BUG_ON(root_cache->memcg_params->memcg_caches[id] != cachep);
root_cache->memcg_params->memcg_caches[id] = NULL;
list_del(&cachep->memcg_params->list);
kmem_cache_destroy(cachep);
/* drop the reference taken in memcg_register_cache */
css_put(&memcg->css);
}
/*
* During the creation a new cache, we need to disable our accounting mechanism
* altogether. This is true even if we are not creating, but rather just
* enqueing new caches to be created.
*
* This is because that process will trigger allocations; some visible, like
* explicit kmallocs to auxiliary data structures, name strings and internal
* cache structures; some well concealed, like INIT_WORK() that can allocate
* objects during debug.
*
* If any allocation happens during memcg_kmem_get_cache, we will recurse back
* to it. This may not be a bounded recursion: since the first cache creation