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linux/mm/memcontrol.c

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/* 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 = 0;
#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;
/*
* 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;
/* set when res.limit == memsw.limit */
bool memsw_is_minimum;
/* 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. per-memcg */
struct list_head memcg_slab_caches;
/* Not a spinlock, we can take a lot of time walking the list */
struct mutex slab_caches_mutex;
/* 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)
/*
* Reclaim flags for mem_cgroup_hierarchical_reclaim
*/
#define MEM_CGROUP_RECLAIM_NOSWAP_BIT 0x0
#define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
#define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1
#define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
/*
* 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)
{
/*
* The ID of the root cgroup is 0, but memcg treat 0 as an
* invalid ID, so we return (cgroup_id + 1).
*/
return memcg->css.cgroup->id + 1;
}
static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
struct cgroup_subsys_state *css;
css = css_from_id(id - 1, &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(&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 disarm_kmem_keys(struct mem_cgroup *memcg)
{
if (memcg_kmem_is_active(memcg)) {
static_key_slow_dec(&memcg_kmem_enabled_key);
ida_simple_remove(&kmem_limited_groups, 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_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
{
VM_BUG_ON((unsigned)nid >= nr_node_ids);
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 *
page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
{
int nid = page_to_nid(page);
int zid = page_zonenum(page);
return mem_cgroup_zoneinfo(memcg, nid, 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 *memcg,
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 *memcg,
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 *memcg,
struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz)
{
spin_lock(&mctz->lock);
__mem_cgroup_remove_exceeded(memcg, mz, mctz);
spin_unlock(&mctz->lock);
}
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;
int nid = page_to_nid(page);
int zid = page_zonenum(page);
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_zoneinfo(memcg, nid, zid);
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) {
spin_lock(&mctz->lock);
/* if on-tree, remove it */
if (mz->on_tree)
__mem_cgroup_remove_exceeded(memcg, mz, mctz);
/*
* Insert again. mz->usage_in_excess will be updated.
* If excess is 0, no tree ops.
*/
__mem_cgroup_insert_exceeded(memcg, mz, mctz, excess);
spin_unlock(&mctz->lock);
}
}
}
static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
{
int node, zone;
struct mem_cgroup_per_zone *mz;
struct mem_cgroup_tree_per_zone *mctz;
for_each_node(node) {
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
mz = mem_cgroup_zoneinfo(memcg, node, zone);
mctz = soft_limit_tree_node_zone(node, zone);
mem_cgroup_remove_exceeded(memcg, 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->memcg, mz, mctz);
if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
!css_tryget(&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(&mctz->lock);
mz = __mem_cgroup_largest_soft_limit_node(mctz);
spin_unlock(&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 void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
bool charge)
{
int val = (charge) ? 1 : -1;
this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], 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,
bool anon, 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 (anon)
__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_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
unsigned int lru_mask)
{
struct mem_cgroup_per_zone *mz;
enum lru_list lru;
unsigned long ret = 0;
mz = mem_cgroup_zoneinfo(memcg, nid, zid);
for_each_lru(lru) {
if (BIT(lru) & lru_mask)
ret += mz->lru_size[lru];
}
return ret;
}
static unsigned long
mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
int nid, unsigned int lru_mask)
{
u64 total = 0;
int zid;
for (zid = 0; zid < MAX_NR_ZONES; zid++)
total += mem_cgroup_zone_nr_lru_pages(memcg,
nid, zid, lru_mask);
return total;
}
static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
unsigned int lru_mask)
{
int nid;
u64 total = 0;
for_each_node_state(nid, N_MEMORY)
total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
return total;
}
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)
{
preempt_disable();
/* 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
preempt_enable();
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
} else
preempt_enable();
}
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 {
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))
memcg = root_mem_cgroup;
} while (!css_tryget(&memcg->css));
rcu_read_unlock();
return memcg;
}
/*
* 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) {
if ((next_css == &root->css) ||
((next_css->flags & CSS_ONLINE) && css_tryget(next_css)))
return mem_cgroup_from_css(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(&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) {
int nid = zone_to_nid(reclaim->zone);
int zid = zone_idx(reclaim->zone);
struct mem_cgroup_per_zone *mz;
mz = mem_cgroup_zoneinfo(root, nid, zid);
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_zoneinfo(memcg, zone_to_nid(zone), zone_idx(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;
}
/*
* Following LRU functions are allowed to be used without PCG_LOCK.
* Operations are called by routine of global LRU independently from memcg.
* What we have to take care of here is validness of pc->mem_cgroup.
*
* Changes to pc->mem_cgroup happens when
* 1. charge
* 2. moving account
* In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
* It is added to LRU before charge.
* If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
* When moving account, the page is not on LRU. It's isolated.
*/
/**
* 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 = page_cgroup_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 (!css_parent(&memcg->css))
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.
*/
/* for quick checking without looking up memcg */
atomic_t memcg_moving __read_mostly;
static void mem_cgroup_start_move(struct mem_cgroup *memcg)
{
atomic_inc(&memcg_moving);
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);
atomic_dec(&memcg->moving_account);
}
}
/*
* 2 routines for checking "mem" is under move_account() or not.
*
* mem_cgroup_stolen() - checking whether a cgroup is mc.from or not. This
* is used for avoiding races in accounting. If true,
* pc->mem_cgroup may be overwritten.
*
* mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
* under hierarchy of moving cgroups. This is for
* waiting at hith-memory prressure caused by "move".
*/
static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
{
VM_BUG_ON(!rcu_read_lock_held());
return atomic_read(&memcg->moving_account) > 0;
}
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.
* see mem_cgroup_stolen(), too.
*/
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");
}
static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg,
gfp_t gfp_mask,
unsigned long flags)
{
unsigned long total = 0;
bool noswap = false;
int loop;
if (flags & MEM_CGROUP_RECLAIM_NOSWAP)
noswap = true;
if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum)
noswap = true;
for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) {
if (loop)
drain_all_stock_async(memcg);
total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap);
/*
* Allow limit shrinkers, which are triggered directly
* by userspace, to catch signals and stop reclaim
* after minimal progress, regardless of the margin.
*/
if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK))
break;
if (mem_cgroup_margin(memcg))
break;
/*
* If nothing was reclaimed after two attempts, there
* may be no reclaimable pages in this hierarchy.
*/
if (loop && !total)
break;
}
return total;
}
/**
* 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;
}
/*
* Currently used to update mapped file statistics, but the routine can be
* generalized to update other statistics as well.
*
* Notes: Race condition
*
* We usually use page_cgroup_lock() for accessing page_cgroup member but
* it tends to be costly. But considering some conditions, we doesn't need
* to do so _always_.
*
* Considering "charge", lock_page_cgroup() is not required because all
* file-stat operations happen after a page is attached to radix-tree. There
* are no race with "charge".
*
* Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
* at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
* if there are race with "uncharge". Statistics itself is properly handled
* by flags.
*
* Considering "move", this is an only case we see a race. To make the race
* small, we check mm->moving_account and detect there are possibility of race
* If there is, we take a lock.
*/
void __mem_cgroup_begin_update_page_stat(struct page *page,
bool *locked, unsigned long *flags)
{
struct mem_cgroup *memcg;
struct page_cgroup *pc;
pc = lookup_page_cgroup(page);
again:
memcg = pc->mem_cgroup;
if (unlikely(!memcg || !PageCgroupUsed(pc)))
return;
/*
* If this memory cgroup is not under account moving, we don't
* need to take move_lock_mem_cgroup(). Because we already hold
* rcu_read_lock(), any calls to move_account will be delayed until
* rcu_read_unlock() if mem_cgroup_stolen() == true.
*/
if (!mem_cgroup_stolen(memcg))
return;
move_lock_mem_cgroup(memcg, flags);
if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
move_unlock_mem_cgroup(memcg, flags);
goto again;
}
*locked = true;
}
void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
{
struct page_cgroup *pc = lookup_page_cgroup(page);
/*
* It's guaranteed that pc->mem_cgroup never changes while
* lock is held because a routine modifies pc->mem_cgroup
* should take move_lock_mem_cgroup().
*/
move_unlock_mem_cgroup(pc->mem_cgroup, flags);
}
void mem_cgroup_update_page_stat(struct page *page,
enum mem_cgroup_stat_index idx, int val)
{
struct mem_cgroup *memcg;
struct page_cgroup *pc = lookup_page_cgroup(page);
unsigned long uninitialized_var(flags);
if (mem_cgroup_disabled())
return;
VM_BUG_ON(!rcu_read_lock_held());
memcg = pc->mem_cgroup;
if (unlikely(!memcg || !PageCgroupUsed(pc)))
return;
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 = &__get_cpu_var(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;
}
/* See mem_cgroup_try_charge() for details */
enum {
CHARGE_OK, /* success */
CHARGE_RETRY, /* need to retry but retry is not bad */
CHARGE_NOMEM, /* we can't do more. return -ENOMEM */
CHARGE_WOULDBLOCK, /* GFP_WAIT wasn't set and no enough res. */
};
static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
unsigned int nr_pages, unsigned int min_pages,
bool invoke_oom)
{
unsigned long csize = nr_pages * PAGE_SIZE;
struct mem_cgroup *mem_over_limit;
struct res_counter *fail_res;
unsigned long flags = 0;
int ret;
ret = res_counter_charge(&memcg->res, csize, &fail_res);
if (likely(!ret)) {
if (!do_swap_account)
return CHARGE_OK;
ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
if (likely(!ret))
return CHARGE_OK;
res_counter_uncharge(&memcg->res, csize);
mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
flags |= MEM_CGROUP_RECLAIM_NOSWAP;
} else
mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
/*
* Never reclaim on behalf of optional batching, retry with a
* single page instead.
*/
if (nr_pages > min_pages)
return CHARGE_RETRY;
if (!(gfp_mask & __GFP_WAIT))
return CHARGE_WOULDBLOCK;
if (gfp_mask & __GFP_NORETRY)
return CHARGE_NOMEM;
ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
return CHARGE_RETRY;
/*
* 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_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret)
return CHARGE_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))
return CHARGE_RETRY;
if (invoke_oom)
mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize));
return CHARGE_NOMEM;
}
/**
* mem_cgroup_try_charge - try charging a memcg
* @memcg: memcg to charge
* @nr_pages: number of pages to charge
* @oom: trigger OOM if reclaim fails
*
* Returns 0 if @memcg was charged successfully, -EINTR if the charge
* was bypassed to root_mem_cgroup, and -ENOMEM if the charge failed.
*/
static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
gfp_t gfp_mask,
unsigned int nr_pages,
bool oom)
{
unsigned int batch = max(CHARGE_BATCH, nr_pages);
int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
int ret;
if (mem_cgroup_is_root(memcg))
goto done;
/*
* 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)))
goto bypass;
if (unlikely(task_in_memcg_oom(current)))
goto nomem;
if (gfp_mask & __GFP_NOFAIL)
oom = false;
again:
if (consume_stock(memcg, nr_pages))
goto done;
do {
bool invoke_oom = oom && !nr_oom_retries;
/* If killed, bypass charge */
if (fatal_signal_pending(current))
goto bypass;
ret = mem_cgroup_do_charge(memcg, gfp_mask, batch,
nr_pages, invoke_oom);
switch (ret) {
case CHARGE_OK:
break;
case CHARGE_RETRY: /* not in OOM situation but retry */
batch = nr_pages;
goto again;
case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
goto nomem;
case CHARGE_NOMEM: /* OOM routine works */
if (!oom || invoke_oom)
goto nomem;
nr_oom_retries--;
break;
}
} while (ret != CHARGE_OK);
if (batch > nr_pages)
refill_stock(memcg, batch - nr_pages);
done:
return 0;
nomem:
if (!(gfp_mask & __GFP_NOFAIL))
return -ENOMEM;
bypass:
return -EINTR;
}
/**
* mem_cgroup_try_charge_mm - try charging a mm
* @mm: mm_struct to charge
* @nr_pages: number of pages to charge
* @oom: trigger OOM if reclaim fails
*
* Returns the charged mem_cgroup associated with the given mm_struct or
* NULL the charge failed.
*/
static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
gfp_t gfp_mask,
unsigned int nr_pages,
bool oom)
{
struct mem_cgroup *memcg;
int ret;
memcg = get_mem_cgroup_from_mm(mm);
ret = mem_cgroup_try_charge(memcg, gfp_mask, nr_pages, oom);
css_put(&memcg->css);
if (ret == -EINTR)
memcg = root_mem_cgroup;
else if (ret)
memcg = NULL;
return memcg;
}
/*
* Somemtimes we have to undo a charge we got by try_charge().
* This function is for that and do uncharge, put css's refcnt.
* gotten by try_charge().
*/
static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
unsigned int nr_pages)
{
if (!mem_cgroup_is_root(memcg)) {
unsigned long bytes = nr_pages * PAGE_SIZE;
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 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);
}
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);
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
memcg = pc->mem_cgroup;
if (memcg && !css_tryget(&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(&memcg->css))
memcg = NULL;
rcu_read_unlock();
}
unlock_page_cgroup(pc);
return memcg;
}
static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
struct page *page,
unsigned int nr_pages,
enum charge_type ctype,
bool lrucare)
{
struct page_cgroup *pc = lookup_page_cgroup(page);
struct zone *uninitialized_var(zone);
struct lruvec *lruvec;
bool was_on_lru = false;
bool anon;
lock_page_cgroup(pc);
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) {
zone = page_zone(page);
spin_lock_irq(&zone->lru_lock);
if (PageLRU(page)) {
lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
ClearPageLRU(page);
del_page_from_lru_list(page, lruvec, page_lru(page));
was_on_lru = true;
}
}
pc->mem_cgroup = memcg;
/*
* We access a page_cgroup asynchronously without lock_page_cgroup().
* Especially when a page_cgroup is taken from a page, pc->mem_cgroup
* is accessed after testing USED bit. To make pc->mem_cgroup visible
* before USED bit, we need memory barrier here.
* See mem_cgroup_add_lru_list(), etc.
*/
smp_wmb();
SetPageCgroupUsed(pc);
if (lrucare) {
if (was_on_lru) {
lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
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);
}
if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON)
anon = true;
else
anon = false;
mem_cgroup_charge_statistics(memcg, page, anon, nr_pages);
unlock_page_cgroup(pc);
/*
* "charge_statistics" updated event counter. Then, check it.
* Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
* if they exceeds softlimit.
*/
memcg_check_events(memcg, page);
}
static DEFINE_MUTEX(set_limit_mutex);
#ifdef CONFIG_MEMCG_KMEM
static DEFINE_MUTEX(activate_kmem_mutex);
static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
{
return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&
memcg_kmem_is_active(memcg);
}
/*
* 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_can_account_kmem(memcg))
return -EIO;
print_slabinfo_header(m);
mutex_lock(&memcg->slab_caches_mutex);
list_for_each_entry(params, &memcg->memcg_slab_caches, list)
cache_show(memcg_params_to_cache(params), m);
mutex_unlock(&memcg->slab_caches_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 = mem_cgroup_try_charge(memcg, gfp, size >> PAGE_SHIFT,
oom_gfp_allowed(gfp));
if (ret == -EINTR) {
/*
* mem_cgroup_try_charge() chosed 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
* mem_cgroup_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 size_t memcg_caches_array_size(int num_groups)
{
ssize_t size;
if (num_groups <= 0)
return 0;
size = 2 * num_groups;
if (size < MEMCG_CACHES_MIN_SIZE)
size = MEMCG_CACHES_MIN_SIZE;
else if (size > MEMCG_CACHES_MAX_SIZE)
size = MEMCG_CACHES_MAX_SIZE;
return size;
}
/*
* 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)
{
if (num > memcg_limited_groups_array_size)
memcg_limited_groups_array_size = memcg_caches_array_size(num);
}
static void kmem_cache_destroy_work_func(struct work_struct *w);
int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
{
struct memcg_cache_params *cur_params = s->memcg_params;
VM_BUG_ON(!is_root_cache(s));
if (num_groups > memcg_limited_groups_array_size) {
int i;
struct memcg_cache_params *new_params;
ssize_t size = memcg_caches_array_size(num_groups);
size *= sizeof(void *);
size += offsetof(struct memcg_cache_params, memcg_caches);
new_params = kzalloc(size, GFP_KERNEL);
if (!new_params)
return -ENOMEM;
new_params->is_root_cache = true;
/*
* There is the chance it will be bigger than
* memcg_limited_groups_array_size, if we failed an allocation
* in a cache, in which case all caches updated before it, will
* have a bigger array.
*
* But if that is the case, the data after
* memcg_limited_groups_array_size is certainly unused
*/
for (i = 0; i < memcg_limited_groups_array_size; i++) {
if (!cur_params->memcg_caches[i])
continue;
new_params->memcg_caches[i] =
cur_params->memcg_caches[i];
}
/*
* Ideally, we would wait until all caches succeed, and only
* then free the old one. But this is not worth the extra
* pointer per-cache we'd have to have for this.
*
* It is not a big deal if some caches are left with a size
* bigger than the others. And all updates will reset this
* anyway.
*/
rcu_assign_pointer(s->memcg_params, new_params);
if (cur_params)
kfree_rcu(cur_params, rcu_head);
}
return 0;
}
char *memcg_create_cache_name(struct mem_cgroup *memcg,
struct kmem_cache *root_cache)
{
static char *buf = NULL;
/*
* We need a mutex here to protect the shared buffer. Since this is
* expected to be called only on cache creation, we can employ the
* slab_mutex for that purpose.
*/
lockdep_assert_held(&slab_mutex);
if (!buf) {
buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
if (!buf)
return NULL;
}
cgroup_name(memcg->css.cgroup, buf, NAME_MAX + 1);
return kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
memcg_cache_id(memcg), buf);
}
int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
struct kmem_cache *root_cache)
{
size_t size;
if (!memcg_kmem_enabled())
return 0;
if (!memcg) {
size = offsetof(struct memcg_cache_params, memcg_caches);
size += memcg_limited_groups_array_size * sizeof(void *);
} else
size = sizeof(struct memcg_cache_params);
s->memcg_params = kzalloc(size, GFP_KERNEL);
if (!s->memcg_params)
return -ENOMEM;
if (memcg) {
s->memcg_params->memcg = memcg;
s->memcg_params->root_cache = root_cache;
INIT_WORK(&s->memcg_params->destroy,
kmem_cache_destroy_work_func);
css_get(&memcg->css);
} else
s->memcg_params->is_root_cache = true;
return 0;
}
void memcg_free_cache_params(struct kmem_cache *s)
{
if (!s->memcg_params)
return;
if (!s->memcg_params->is_root_cache)
css_put(&s->memcg_params->memcg->css);
kfree(s->memcg_params);
}
void memcg_register_cache(struct kmem_cache *s)
{
struct kmem_cache *root;
struct mem_cgroup *memcg;
int id;
if (is_root_cache(s))
return;
/*
* Holding the slab_mutex assures nobody will touch the memcg_caches
* array while we are modifying it.
*/
lockdep_assert_held(&slab_mutex);
root = s->memcg_params->root_cache;
memcg = s->memcg_params->memcg;
id = memcg_cache_id(memcg);
/*
* 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();
/*
* Initialize the pointer to this cache in its parent's memcg_params
* before adding it to the memcg_slab_caches list, otherwise we can
* fail to convert memcg_params_to_cache() while traversing the list.
*/
VM_BUG_ON(root->memcg_params->memcg_caches[id]);
root->memcg_params->memcg_caches[id] = s;
mutex_lock(&memcg->slab_caches_mutex);
list_add(&s->memcg_params->list, &memcg->memcg_slab_caches);
mutex_unlock(&memcg->slab_caches_mutex);
}
void memcg_unregister_cache(struct kmem_cache *s)
{
struct kmem_cache *root;
struct mem_cgroup *memcg;
int id;
if (is_root_cache(s))
return;
/*
* Holding the slab_mutex assures nobody will touch the memcg_caches
* array while we are modifying it.
*/
lockdep_assert_held(&slab_mutex);
root = s->memcg_params->root_cache;
memcg = s->memcg_params->memcg;
id = memcg_cache_id(memcg);
mutex_lock(&memcg->slab_caches_mutex);
list_del(&s->memcg_params->list);
mutex_unlock(&memcg->slab_caches_mutex);
/*
* Clear the pointer to this cache in its parent's memcg_params only
* after removing it from the memcg_slab_caches list, otherwise we can
* fail to convert memcg_params_to_cache() while traversing the list.
*/
VM_BUG_ON(root->memcg_params->memcg_caches[id] != s);
root->memcg_params->memcg_caches[id] = NULL;
}
/*
* 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
* failed to complete (waiting on the allocation), we'll just try to create the
* cache again, failing at the same point.
*
* memcg_kmem_get_cache is prepared to abort after seeing a positive count of
* memcg_kmem_skip_account. So we enclose anything that might allocate memory
* inside the following two functions.
*/
static inline void memcg_stop_kmem_account(void)
{
VM_BUG_ON(!current->mm);
current->memcg_kmem_skip_account++;
}
static inline void memcg_resume_kmem_account(void)
{
VM_BUG_ON(!current->mm);
current->memcg_kmem_skip_account--;
}
static void kmem_cache_destroy_work_func(struct work_struct *w)
{
struct kmem_cache *cachep;
struct memcg_cache_params *p;
p = container_of(w, struct memcg_cache_params, destroy);
cachep = memcg_params_to_cache(p);
/*
* If we get down to 0 after shrink, we could delete right away.
* However, memcg_release_pages() already puts us back in the workqueue
* in that case. If we proceed deleting, we'll get a dangling
* reference, and removing the object from the workqueue in that case
* is unnecessary complication. We are not a fast path.
*
* Note that this case is fundamentally different from racing with
* shrink_slab(): if memcg_cgroup_destroy_cache() is called in
* kmem_cache_shrink, not only we would be reinserting a dead cache
* into the queue, but doing so from inside the worker racing to
* destroy it.
*
* So if we aren't down to zero, we'll just schedule a worker and try
* again
*/
if (atomic_read(&cachep->memcg_params->nr_pages) != 0)
kmem_cache_shrink(cachep);
else
kmem_cache_destroy(cachep);
}
void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
{
if (!cachep->memcg_params->dead)
return;
/*
* There are many ways in which we can get here.
*
* We can get to a memory-pressure situation while the delayed work is
* still pending to run. The vmscan shrinkers can then release all
* cache memory and get us to destruction. If this is the case, we'll
* be executed twice, which is a bug (the second time will execute over
* bogus data). In this case, cancelling the work should be fine.
*
* But we can also get here from the worker itself, if
* kmem_cache_shrink is enough to shake all the remaining objects and
* get the page count to 0. In this case, we'll deadlock if we try to
* cancel the work (the worker runs with an internal lock held, which
* is the same lock we would hold for cancel_work_sync().)
*
* Since we can't possibly know who got us here, just refrain from
* running if there is already work pending
*/
if (work_pending(&cachep->memcg_params->destroy))
return;
/*
* We have to defer the actual destroying to a workqueue, because
* we might currently be in a context that cannot sleep.
*/
schedule_work(&cachep->memcg_params->destroy);
}
int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
{
struct kmem_cache *c;
int i, failed = 0;
/*
* If the cache is being destroyed, we trust that there is no one else
* requesting objects from it. Even if there are, the sanity checks in
* kmem_cache_destroy should caught this ill-case.
*
* Still, we don't want anyone else freeing memcg_caches under our
* noses, which can happen if a new memcg comes to life. As usual,
* we'll take the activate_kmem_mutex to protect ourselves against
* this.
*/
mutex_lock(&activate_kmem_mutex);
for_each_memcg_cache_index(i) {
c = cache_from_memcg_idx(s, i);
if (!c)
continue;
/*
* We will now manually delete the caches, so to avoid races
* we need to cancel all pending destruction workers and
* proceed with destruction ourselves.
*
* kmem_cache_destroy() will call kmem_cache_shrink internally,
* and that could spawn the workers again: it is likely that
* the cache still have active pages until this very moment.
* This would lead us back to mem_cgroup_destroy_cache.
*
* But that will not execute at all if the "dead" flag is not
* set, so flip it down to guarantee we are in control.
*/
c->memcg_params->dead = false;
cancel_work_sync(&c->memcg_params->destroy);
kmem_cache_destroy(c);
if (cache_from_memcg_idx(s, i))
failed++;
}
mutex_unlock(&activate_kmem_mutex);
return failed;
}
static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
{
struct kmem_cache *cachep;
struct memcg_cache_params *params;
if (!memcg_kmem_is_active(memcg))
return;
mutex_lock(&memcg->slab_caches_mutex);
list_for_each_entry(params, &memcg->memcg_slab_caches, list) {
cachep = memcg_params_to_cache(params);
cachep->memcg_params->dead = true;
schedule_work(&cachep->memcg_params->destroy);
}
mutex_unlock(&memcg->slab_caches_mutex);
}
struct create_work {
struct mem_cgroup *memcg;
struct kmem_cache *cachep;
struct work_struct work;
};
static void memcg_create_cache_work_func(struct work_struct *w)
{
struct create_work *cw = container_of(w, struct create_work, work);
struct mem_cgroup *memcg = cw->memcg;
struct kmem_cache *cachep = cw->cachep;
kmem_cache_create_memcg(memcg, cachep);
css_put(&memcg->css);
kfree(cw);
}
/*
* Enqueue the creation of a per-memcg kmem_cache.
*/
static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
struct kmem_cache *cachep)
{
struct create_work *cw;
cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
if (cw == NULL) {
css_put(&memcg->css);
return;
}
cw->memcg = memcg;
cw->cachep = cachep;
INIT_WORK(&cw->work, memcg_create_cache_work_func);
schedule_work(&cw->work);
}
static void memcg_create_cache_enqueue(struct mem_cgroup *memcg,
struct kmem_cache *cachep)
{
/*
* We need to stop accounting when we kmalloc, because if the
* corresponding kmalloc cache is not yet created, the first allocation
* in __memcg_create_cache_enqueue will recurse.
*
* However, it is better to enclose the whole function. Depending on
* the debugging options enabled, INIT_WORK(), for instance, can
* trigger an allocation. This too, will make us recurse. Because at
* this point we can't allow ourselves back into memcg_kmem_get_cache,
* the safest choice is to do it like this, wrapping the whole function.
*/
memcg_stop_kmem_account();
__memcg_create_cache_enqueue(memcg, cachep);
memcg_resume_kmem_account();
}
/*
* 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 either create it immediately, if possible, or create it asynchronously
* in a workqueue.
* In the latter case, we will let the current allocation go through with
* the original cache.
*
* Can't be called in interrupt context or from kernel threads.
* This function needs to be called with rcu_read_lock() held.
*/
struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
gfp_t gfp)
{
struct mem_cgroup *memcg;
struct kmem_cache *memcg_cachep;
VM_BUG_ON(!cachep->memcg_params);
VM_BUG_ON(!cachep->memcg_params->is_root_cache);
if (!current->mm || current->memcg_kmem_skip_account)
return cachep;
rcu_read_lock();
memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));
if (!memcg_can_account_kmem(memcg))
goto out;
memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg));
if (likely(memcg_cachep)) {
cachep = memcg_cachep;
goto out;
}
/* The corresponding put will be done in the workqueue. */
if (!css_tryget(&memcg->css))
goto out;
rcu_read_unlock();
/*
* 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
* kmem_cache_dup, this means no further allocation could happen
* with the slab_mutex held.
*
* Also, because cache creation issue get_online_cpus(), this
* creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
* that ends up reversed during cpu hotplug. (cpuset allocates
* a bunch of GFP_KERNEL memory during cpuup). Due to all that,
* better to defer everything.
*/
memcg_create_cache_enqueue(memcg, cachep);
return cachep;
out:
rcu_read_unlock();
return cachep;
}
EXPORT_SYMBOL(__memcg_kmem_get_cache);
/*
* We need to verify if the allocation against current->mm->owner's memcg is
* possible for the given order. But the page is not allocated yet, so we'll
* need a further commit step to do the final arrangements.
*
* It is possible for the task to switch cgroups in this mean time, so at
* commit time, we can't rely on task conversion any longer. We'll then use
* the handle argument to return to the caller which cgroup we should commit
* against. We could also return the memcg directly and avoid the pointer
* passing, but a boolean return value gives better semantics considering
* the compiled-out case as well.
*
* Returning true means the allocation is possible.
*/
bool
__memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order)
{
struct mem_cgroup *memcg;
int ret;
*_memcg = NULL;
/*
* Disabling accounting is only relevant for some specific memcg
* internal allocations. Therefore we would initially not have such
* check here, since direct calls to the page allocator that are marked
* with GFP_KMEMCG only happen outside memcg core. We are mostly
* concerned with cache allocations, and by having this test at
* memcg_kmem_get_cache, we are already able to relay the allocation to
* the root cache and bypass the memcg cache altogether.
*
* There is one exception, though: the SLUB allocator does not create
* large order caches, but rather service large kmallocs directly from
* the page allocator. Therefore, the following sequence when backed by
* the SLUB allocator:
*
* memcg_stop_kmem_account();
* kmalloc(<large_number>)
* memcg_resume_kmem_account();
*
* would effectively ignore the fact that we should skip accounting,
* since it will drive us directly to this function without passing
* through the cache selector memcg_kmem_get_cache. Such large
* allocations are extremely rare but can happen, for instance, for the
* cache arrays. We bring this test here.
*/
if (!current->mm || current->memcg_kmem_skip_account)
return true;
memcg = get_mem_cgroup_from_mm(current->mm);
if (!memcg_can_account_kmem(memcg)) {
css_put(&memcg->css);
return true;
}
ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order);
if (!ret)
*_memcg = memcg;
css_put(&memcg->css);
return (ret == 0);
}
void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg,
int order)
{
struct page_cgroup *pc;
VM_BUG_ON(mem_cgroup_is_root(memcg));
/* The page allocation failed. Revert */
if (!page) {
memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
return;
}
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
pc->mem_cgroup = memcg;
SetPageCgroupUsed(pc);
unlock_page_cgroup(pc);
}
void __memcg_kmem_uncharge_pages(struct page *page, int order)
{
struct mem_cgroup *memcg = NULL;
struct page_cgroup *pc;
pc = lookup_page_cgroup(page);
/*
* Fast unlocked return. Theoretically might have changed, have to
* check again after locking.
*/
if (!PageCgroupUsed(pc))
return;
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
memcg = pc->mem_cgroup;
ClearPageCgroupUsed(pc);
}
unlock_page_cgroup(pc);
/*
* We trust that only if there is a memcg associated with the page, it
* is a valid allocation
*/
if (!memcg)
return;
VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
}
#else
static inline void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
{
}
#endif /* CONFIG_MEMCG_KMEM */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION)
/*
* Because tail pages are not marked as "used", set it. We're under
* zone->lru_lock, 'splitting on pmd' and compound_lock.
* charge/uncharge will be never happen and move_account() is done under
* compound_lock(), so we don't have to take care of races.
*/
void mem_cgroup_split_huge_fixup(struct page *head)
{
struct page_cgroup *head_pc = lookup_page_cgroup(head);
struct page_cgroup *pc;
struct mem_cgroup *memcg;
int i;
if (mem_cgroup_disabled())
return;
memcg = head_pc->mem_cgroup;
for (i = 1; i < HPAGE_PMD_NR; i++) {
pc = head_pc + i;
pc->mem_cgroup = memcg;
smp_wmb();/* see __commit_charge() */
pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
}
__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
HPAGE_PMD_NR);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/**
* mem_cgroup_move_account - move account of the page
* @page: the page
* @nr_pages: number of regular pages (>1 for huge pages)
* @pc: page_cgroup of the page.
* @from: mem_cgroup which the page is moved from.
* @to: mem_cgroup which the page is moved to. @from != @to.
*
* The caller must confirm following.
* - page is not on LRU (isolate_page() is useful.)
* - compound_lock is held when nr_pages > 1
*
* This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
* from old cgroup.
*/
static int mem_cgroup_move_account(struct page *page,
unsigned int nr_pages,
struct page_cgroup *pc,
struct mem_cgroup *from,
struct mem_cgroup *to)
{
unsigned long flags;
int ret;
bool anon = PageAnon(page);
VM_BUG_ON(from == to);
VM_BUG_ON_PAGE(PageLRU(page), page);
/*
* The page is isolated from LRU. So, collapse function
* will not handle this page. But page splitting can happen.
* Do this check under compound_page_lock(). The caller should
* hold it.
*/
ret = -EBUSY;
if (nr_pages > 1 && !PageTransHuge(page))
goto out;
lock_page_cgroup(pc);
ret = -EINVAL;
if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
goto unlock;
move_lock_mem_cgroup(from, &flags);
if (!anon && page_mapped(page)) {
__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
nr_pages);
__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
nr_pages);
}
if (PageWriteback(page)) {
__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK],
nr_pages);
__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK],
nr_pages);
}
mem_cgroup_charge_statistics(from, page, anon, -nr_pages);
/* caller should have done css_get */
pc->mem_cgroup = to;
mem_cgroup_charge_statistics(to, page, anon, nr_pages);
move_unlock_mem_cgroup(from, &flags);
ret = 0;
unlock:
unlock_page_cgroup(pc);
/*
* check events
*/
memcg_check_events(to, page);
memcg_check_events(from, page);
out:
return ret;
}
/**
* mem_cgroup_move_parent - moves page to the parent group
* @page: the page to move
* @pc: page_cgroup of the page
* @child: page's cgroup
*
* move charges to its parent or the root cgroup if the group has no
* parent (aka use_hierarchy==0).
* Although this might fail (get_page_unless_zero, isolate_lru_page or
* mem_cgroup_move_account fails) the failure is always temporary and
* it signals a race with a page removal/uncharge or migration. In the
* first case the page is on the way out and it will vanish from the LRU
* on the next attempt and the call should be retried later.
* Isolation from the LRU fails only if page has been isolated from
* the LRU since we looked at it and that usually means either global
* reclaim or migration going on. The page will either get back to the
* LRU or vanish.
* Finaly mem_cgroup_move_account fails only if the page got uncharged
* (!PageCgroupUsed) or moved to a different group. The page will
* disappear in the next attempt.
*/
static int mem_cgroup_move_parent(struct page *page,
struct page_cgroup *pc,
struct mem_cgroup *child)
{
struct mem_cgroup *parent;
unsigned int nr_pages;
unsigned long uninitialized_var(flags);
int ret;
VM_BUG_ON(mem_cgroup_is_root(child));
ret = -EBUSY;
if (!get_page_unless_zero(page))
goto out;
if (isolate_lru_page(page))
goto put;
nr_pages = hpage_nr_pages(page);
parent = parent_mem_cgroup(child);
/*
* If no parent, move charges to root cgroup.
*/
if (!parent)
parent = root_mem_cgroup;
if (nr_pages > 1) {
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
flags = compound_lock_irqsave(page);
}
ret = mem_cgroup_move_account(page, nr_pages,
pc, child, parent);
if (!ret)
__mem_cgroup_cancel_local_charge(child, nr_pages);
if (nr_pages > 1)
compound_unlock_irqrestore(page, flags);
putback_lru_page(page);
put:
put_page(page);
out:
return ret;
}
int mem_cgroup_charge_anon(struct page *page,
struct mm_struct *mm, gfp_t gfp_mask)
{
unsigned int nr_pages = 1;
struct mem_cgroup *memcg;
bool oom = true;
if (mem_cgroup_disabled())
return 0;
VM_BUG_ON_PAGE(page_mapped(page), page);
VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
VM_BUG_ON(!mm);
if (PageTransHuge(page)) {
nr_pages <<= compound_order(page);
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
/*
* Never OOM-kill a process for a huge page. The
* fault handler will fall back to regular pages.
*/
oom = false;
}
memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom);
if (!memcg)
return -ENOMEM;
__mem_cgroup_commit_charge(memcg, page, nr_pages,
MEM_CGROUP_CHARGE_TYPE_ANON, false);
return 0;
}
/*
* While swap-in, try_charge -> commit or cancel, the page is locked.
* And when try_charge() successfully returns, one refcnt to memcg without
* struct page_cgroup is acquired. This refcnt will be consumed by
* "commit()" or removed by "cancel()"
*/
static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
struct page *page,
gfp_t mask,
struct mem_cgroup **memcgp)
{
struct mem_cgroup *memcg = NULL;
struct page_cgroup *pc;
int ret;
pc = lookup_page_cgroup(page);
/*
* Every swap fault against a single page tries to charge the
* page, bail as early as possible. shmem_unuse() encounters
* already charged pages, too. The USED bit is protected by
* the page lock, which serializes swap cache removal, which
* in turn serializes uncharging.
*/
if (PageCgroupUsed(pc))
goto out;
if (do_swap_account)
memcg = try_get_mem_cgroup_from_page(page);
if (!memcg)
memcg = get_mem_cgroup_from_mm(mm);
ret = mem_cgroup_try_charge(memcg, mask, 1, true);
css_put(&memcg->css);
if (ret == -EINTR)
memcg = root_mem_cgroup;
else if (ret)
return ret;
out:
*memcgp = memcg;
return 0;
}
int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
gfp_t gfp_mask, struct mem_cgroup **memcgp)
{
if (mem_cgroup_disabled()) {
*memcgp = NULL;
return 0;
}
/*
* A racing thread's fault, or swapoff, may have already
* updated the pte, and even removed page from swap cache: in
* those cases unuse_pte()'s pte_same() test will fail; but
* there's also a KSM case which does need to charge the page.
*/
if (!PageSwapCache(page)) {
struct mem_cgroup *memcg;
memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
if (!memcg)
return -ENOMEM;
*memcgp = memcg;
return 0;
}
return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp);
}
void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
{
if (mem_cgroup_disabled())
return;
if (!memcg)
return;
__mem_cgroup_cancel_charge(memcg, 1);
}
static void
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
enum charge_type ctype)
{
if (mem_cgroup_disabled())
return;
if (!memcg)
return;
__mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
/*
* Now swap is on-memory. This means this page may be
* counted both as mem and swap....double count.
* Fix it by uncharging from memsw. Basically, this SwapCache is stable
* under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
* may call delete_from_swap_cache() before reach here.
*/
if (do_swap_account && PageSwapCache(page)) {
swp_entry_t ent = {.val = page_private(page)};
mem_cgroup_uncharge_swap(ent);
}
}
void mem_cgroup_commit_charge_swapin(struct page *page,
struct mem_cgroup *memcg)
{
__mem_cgroup_commit_charge_swapin(page, memcg,
MEM_CGROUP_CHARGE_TYPE_ANON);
}
int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
struct mem_cgroup *memcg;
int ret;
if (mem_cgroup_disabled())
return 0;
if (PageCompound(page))
return 0;
if (PageSwapCache(page)) { /* shmem */
ret = __mem_cgroup_try_charge_swapin(mm, page,
gfp_mask, &memcg);
if (ret)
return ret;
__mem_cgroup_commit_charge_swapin(page, memcg, type);
return 0;
}
/*
* Page cache insertions can happen without an actual mm
* context, e.g. during disk probing on boot.
*/
if (unlikely(!mm))
memcg = root_mem_cgroup;
else {
memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
if (!memcg)
return -ENOMEM;
}
__mem_cgroup_commit_charge(memcg, page, 1, type, false);
return 0;
}
static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
unsigned int nr_pages,
const enum charge_type ctype)
{
struct memcg_batch_info *batch = NULL;
bool uncharge_memsw = true;
/* If swapout, usage of swap doesn't decrease */
if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
uncharge_memsw = false;
batch = &current->memcg_batch;
/*
* In usual, we do css_get() when we remember memcg pointer.
* But in this case, we keep res->usage until end of a series of
* uncharges. Then, it's ok to ignore memcg's refcnt.
*/
if (!batch->memcg)
batch->memcg = memcg;
/*
* do_batch > 0 when unmapping pages or inode invalidate/truncate.
* In those cases, all pages freed continuously can be expected to be in
* the same cgroup and we have chance to coalesce uncharges.
* But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
* because we want to do uncharge as soon as possible.
*/
if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
goto direct_uncharge;
if (nr_pages > 1)
goto direct_uncharge;
/*
* In typical case, batch->memcg == mem. This means we can
* merge a series of uncharges to an uncharge of res_counter.
* If not, we uncharge res_counter ony by one.
*/
if (batch->memcg != memcg)
goto direct_uncharge;
/* remember freed charge and uncharge it later */
batch->nr_pages++;
if (uncharge_memsw)
batch->memsw_nr_pages++;
return;
direct_uncharge:
res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
if (uncharge_memsw)
res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
if (unlikely(batch->memcg != memcg))
memcg_oom_recover(memcg);
}
/*
* uncharge if !page_mapped(page)
*/
static struct mem_cgroup *
__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
bool end_migration)
{
struct mem_cgroup *memcg = NULL;
unsigned int nr_pages = 1;
struct page_cgroup *pc;
bool anon;
if (mem_cgroup_disabled())
return NULL;
if (PageTransHuge(page)) {
nr_pages <<= compound_order(page);
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
}
/*
* Check if our page_cgroup is valid
*/
pc = lookup_page_cgroup(page);
if (unlikely(!PageCgroupUsed(pc)))
return NULL;
lock_page_cgroup(pc);
memcg = pc->mem_cgroup;
if (!PageCgroupUsed(pc))
goto unlock_out;
anon = PageAnon(page);
switch (ctype) {
case MEM_CGROUP_CHARGE_TYPE_ANON:
/*
* Generally PageAnon tells if it's the anon statistics to be
* updated; but sometimes e.g. mem_cgroup_uncharge_page() is
* used before page reached the stage of being marked PageAnon.
*/
anon = true;
/* fallthrough */
case MEM_CGROUP_CHARGE_TYPE_DROP:
/* See mem_cgroup_prepare_migration() */
if (page_mapped(page))
goto unlock_out;
/*
* Pages under migration may not be uncharged. But
* end_migration() /must/ be the one uncharging the
* unused post-migration page and so it has to call
* here with the migration bit still set. See the
* res_counter handling below.
*/
if (!end_migration && PageCgroupMigration(pc))
goto unlock_out;
break;
case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
if (!PageAnon(page)) { /* Shared memory */
if (page->mapping && !page_is_file_cache(page))
goto unlock_out;
} else if (page_mapped(page)) /* Anon */
goto unlock_out;
break;
default:
break;
}
mem_cgroup_charge_statistics(memcg, page, anon, -nr_pages);
ClearPageCgroupUsed(pc);
/*
* pc->mem_cgroup is not cleared here. It will be accessed when it's
* freed from LRU. This is safe because uncharged page is expected not
* to be reused (freed soon). Exception is SwapCache, it's handled by
* special functions.
*/
unlock_page_cgroup(pc);
/*
* even after unlock, we have memcg->res.usage here and this memcg
* will never be freed, so it's safe to call css_get().
*/
memcg_check_events(memcg, page);
if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
mem_cgroup_swap_statistics(memcg, true);
css_get(&memcg->css);
}
/*
* Migration does not charge the res_counter for the
* replacement page, so leave it alone when phasing out the
* page that is unused after the migration.
*/
if (!end_migration && !mem_cgroup_is_root(memcg))
mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
return memcg;
unlock_out:
unlock_page_cgroup(pc);
return NULL;
}
void mem_cgroup_uncharge_page(struct page *page)
{
/* early check. */
if (page_mapped(page))
return;
VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
/*
* If the page is in swap cache, uncharge should be deferred
* to the swap path, which also properly accounts swap usage
* and handles memcg lifetime.
*
* Note that this check is not stable and reclaim may add the
* page to swap cache at any time after this. However, if the
* page is not in swap cache by the time page->mapcount hits
* 0, there won't be any page table references to the swap
* slot, and reclaim will free it and not actually write the
* page to disk.
*/
if (PageSwapCache(page))
return;
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
}
void mem_cgroup_uncharge_cache_page(struct page *page)
{
VM_BUG_ON_PAGE(page_mapped(page), page);
VM_BUG_ON_PAGE(page->mapping, page);
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
}
/*
* Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
* In that cases, pages are freed continuously and we can expect pages
* are in the same memcg. All these calls itself limits the number of
* pages freed at once, then uncharge_start/end() is called properly.
* This may be called prural(2) times in a context,
*/
void mem_cgroup_uncharge_start(void)
{
current->memcg_batch.do_batch++;
/* We can do nest. */
if (current->memcg_batch.do_batch == 1) {
current->memcg_batch.memcg = NULL;
current->memcg_batch.nr_pages = 0;
current->memcg_batch.memsw_nr_pages = 0;
}
}
void mem_cgroup_uncharge_end(void)
{
struct memcg_batch_info *batch = &current->memcg_batch;
if (!batch->do_batch)
return;
batch->do_batch--;
if (batch->do_batch) /* If stacked, do nothing. */
return;
if (!batch->memcg)
return;
/*
* This "batch->memcg" is valid without any css_get/put etc...
* bacause we hide charges behind us.
*/
if (batch->nr_pages)
res_counter_uncharge(&batch->memcg->res,
batch->nr_pages * PAGE_SIZE);
if (batch->memsw_nr_pages)
res_counter_uncharge(&batch->memcg->memsw,
batch->memsw_nr_pages * PAGE_SIZE);
memcg_oom_recover(batch->memcg);
/* forget this pointer (for sanity check) */
batch->memcg = NULL;
}
#ifdef CONFIG_SWAP
/*
* called after __delete_from_swap_cache() and drop "page" account.
* memcg information is recorded to swap_cgroup of "ent"
*/
void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
{
struct mem_cgroup *memcg;
int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
if (!swapout) /* this was a swap cache but the swap is unused ! */
ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
memcg = __mem_cgroup_uncharge_common(page, ctype, false);
/*
* record memcg information, if swapout && memcg != NULL,
* css_get() was called in uncharge().
*/
if (do_swap_account && swapout && memcg)
swap_cgroup_record(ent, mem_cgroup_id(memcg));
}
#endif
#ifdef CONFIG_MEMCG_SWAP
/*
* called from swap_entry_free(). remove record in swap_cgroup and
* uncharge "memsw" account.
*/
void mem_cgroup_uncharge_swap(swp_entry_t ent)
{
struct mem_cgroup *memcg;
unsigned short id;
if (!do_swap_account)
return;
id = swap_cgroup_record(ent, 0);
rcu_read_lock();
memcg = mem_cgroup_lookup(id);
if (memcg) {
/*
* We uncharge this because swap is freed.
* This memcg can be obsolete one. We avoid calling css_tryget
*/
if (!mem_cgroup_is_root(memcg))
res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
mem_cgroup_swap_statistics(memcg, false);
css_put(&memcg->css);
}
rcu_read_unlock();
}
/**
* 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 res_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) {
mem_cgroup_swap_statistics(from, false);
mem_cgroup_swap_statistics(to, true);
/*
* This function is only called from task migration context now.
* It postpones res_counter and refcount handling till the end
* of task migration(mem_cgroup_clear_mc()) for performance
* improvement. But we cannot postpone css_get(to) because if
* the process that has been moved to @to does swap-in, the
* refcount of @to might be decreased to 0.
*
* We are in attach() phase, so the cgroup is guaranteed to be
* alive, so we can just call css_get().
*/
css_get(&to->css);
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
/*
* Before starting migration, account PAGE_SIZE to mem_cgroup that the old
* page belongs to.
*/
void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
struct mem_cgroup **memcgp)
{
struct mem_cgroup *memcg = NULL;
unsigned int nr_pages = 1;
struct page_cgroup *pc;
enum charge_type ctype;
*memcgp = NULL;
if (mem_cgroup_disabled())
return;
if (PageTransHuge(page))
nr_pages <<= compound_order(page);
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
memcg = pc->mem_cgroup;
css_get(&memcg->css);
/*
* At migrating an anonymous page, its mapcount goes down
* to 0 and uncharge() will be called. But, even if it's fully
* unmapped, migration may fail and this page has to be
* charged again. We set MIGRATION flag here and delay uncharge
* until end_migration() is called
*
* Corner Case Thinking
* A)
* When the old page was mapped as Anon and it's unmap-and-freed
* while migration was ongoing.
* If unmap finds the old page, uncharge() of it will be delayed
* until end_migration(). If unmap finds a new page, it's
* uncharged when it make mapcount to be 1->0. If unmap code
* finds swap_migration_entry, the new page will not be mapped
* and end_migration() will find it(mapcount==0).
*
* B)
* When the old page was mapped but migraion fails, the kernel
* remaps it. A charge for it is kept by MIGRATION flag even
* if mapcount goes down to 0. We can do remap successfully
* without charging it again.
*
* C)
* The "old" page is under lock_page() until the end of
* migration, so, the old page itself will not be swapped-out.
* If the new page is swapped out before end_migraton, our
* hook to usual swap-out path will catch the event.
*/
if (PageAnon(page))
SetPageCgroupMigration(pc);
}
unlock_page_cgroup(pc);
/*
* If the page is not charged at this point,
* we return here.
*/
if (!memcg)
return;
*memcgp = memcg;
/*
* We charge new page before it's used/mapped. So, even if unlock_page()
* is called before end_migration, we can catch all events on this new
* page. In the case new page is migrated but not remapped, new page's
* mapcount will be finally 0 and we call uncharge in end_migration().
*/
if (PageAnon(page))
ctype = MEM_CGROUP_CHARGE_TYPE_ANON;
else
ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
/*
* The page is committed to the memcg, but it's not actually
* charged to the res_counter since we plan on replacing the
* old one and only one page is going to be left afterwards.
*/
__mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false);
}
/* remove redundant charge if migration failed*/
void mem_cgroup_end_migration(struct mem_cgroup *memcg,
struct page *oldpage, struct page *newpage, bool migration_ok)
{
struct page *used, *unused;
struct page_cgroup *pc;
bool anon;
if (!memcg)
return;
if (!migration_ok) {
used = oldpage;
unused = newpage;
} else {
used = newpage;
unused = oldpage;
}
anon = PageAnon(used);
__mem_cgroup_uncharge_common(unused,
anon ? MEM_CGROUP_CHARGE_TYPE_ANON
: MEM_CGROUP_CHARGE_TYPE_CACHE,
true);
css_put(&memcg->css);
/*
* We disallowed uncharge of pages under migration because mapcount
* of the page goes down to zero, temporarly.
* Clear the flag and check the page should be charged.
*/
pc = lookup_page_cgroup(oldpage);
lock_page_cgroup(pc);
ClearPageCgroupMigration(pc);
unlock_page_cgroup(pc);
/*
* If a page is a file cache, radix-tree replacement is very atomic
* and we can skip this check. When it was an Anon page, its mapcount
* goes down to 0. But because we added MIGRATION flage, it's not
* uncharged yet. There are several case but page->mapcount check
* and USED bit check in mem_cgroup_uncharge_page() will do enough
* check. (see prepare_charge() also)
*/
if (anon)
mem_cgroup_uncharge_page(used);
}
/*
* At replace page cache, newpage is not under any memcg but it's on
* LRU. So, this function doesn't touch res_counter but handles LRU
* in correct way. Both pages are locked so we cannot race with uncharge.
*/
void mem_cgroup_replace_page_cache(struct page *oldpage,
struct page *newpage)
{
struct mem_cgroup *memcg = NULL;
struct page_cgroup *pc;
enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
if (mem_cgroup_disabled())
return;
pc = lookup_page_cgroup(oldpage);
/* fix accounting on old pages */
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
memcg = pc->mem_cgroup;
mem_cgroup_charge_statistics(memcg, oldpage, false, -1);
ClearPageCgroupUsed(pc);
}
unlock_page_cgroup(pc);
/*
* When called from shmem_replace_page(), in some cases the
* oldpage has already been charged, and in some cases not.
*/
if (!memcg)
return;
/*
* Even if newpage->mapping was NULL before starting replacement,
* the newpage may be on LRU(or pagevec for LRU) already. We lock
* LRU while we overwrite pc->mem_cgroup.
*/
__mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
}
#ifdef CONFIG_DEBUG_VM
static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
{
struct page_cgroup *pc;
pc = lookup_page_cgroup(page);
/*
* Can be NULL while feeding pages into the page allocator for
* the first time, i.e. during boot or memory hotplug;
* or when mem_cgroup_disabled().
*/
if (likely(pc) && PageCgroupUsed(pc))
return pc;
return NULL;
}
bool mem_cgroup_bad_page_check(struct page *page)
{
if (mem_cgroup_disabled())
return false;
return lookup_page_cgroup_used(page) != NULL;
}
void mem_cgroup_print_bad_page(struct page *page)
{
struct page_cgroup *pc;
pc = lookup_page_cgroup_used(page);
if (pc) {
pr_alert("pc:%p pc->flags:%lx pc->mem_cgroup:%p\n",
pc, pc->flags, pc->mem_cgroup);
}
}
#endif
static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
int retry_count;
u64 memswlimit, memlimit;
int ret = 0;
int children = mem_cgroup_count_children(memcg);
u64 curusage, oldusage;
int enlarge;
/*
* For keeping hierarchical_reclaim simple, how long we should retry
* is depends on callers. We set our retry-count to be function
* of # of children which we should visit in this loop.
*/
retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
enlarge = 0;
while (retry_count) {
if (signal_pending(current)) {
ret = -EINTR;
break;
}
/*
* Rather than hide all in some function, I do this in
* open coded manner. You see what this really does.
* We have to guarantee memcg->res.limit <= memcg->memsw.limit.
*/
mutex_lock(&set_limit_mutex);
memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
if (memswlimit < val) {
ret = -EINVAL;
mutex_unlock(&set_limit_mutex);
break;
}
memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
if (memlimit < val)
enlarge = 1;
ret = res_counter_set_limit(&memcg->res, val);
if (!ret) {
if (memswlimit == val)
memcg->memsw_is_minimum = true;
else
memcg->memsw_is_minimum = false;
}
mutex_unlock(&set_limit_mutex);
if (!ret)
break;
mem_cgroup_reclaim(memcg, GFP_KERNEL,
MEM_CGROUP_RECLAIM_SHRINK);
curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
/* Usage is reduced ? */
if (curusage >= oldusage)
retry_count--;
else
oldusage = curusage;
}
if (!ret && enlarge)
memcg_oom_recover(memcg);
return ret;
}
static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
int retry_count;
u64 memlimit, memswlimit, oldusage, curusage;
int children = mem_cgroup_count_children(memcg);
int ret = -EBUSY;
int enlarge = 0;
/* see mem_cgroup_resize_res_limit */
retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
while (retry_count) {
if (signal_pending(current)) {
ret = -EINTR;
break;
}
/*
* Rather than hide all in some function, I do this in
* open coded manner. You see what this really does.
* We have to guarantee memcg->res.limit <= memcg->memsw.limit.
*/
mutex_lock(&set_limit_mutex);
memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
if (memlimit > val) {
ret = -EINVAL;
mutex_unlock(&set_limit_mutex);
break;
}
memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
if (memswlimit < val)
enlarge = 1;
ret = res_counter_set_limit(&memcg->memsw, val);
if (!ret) {
if (memlimit == val)
memcg->memsw_is_minimum = true;
else
memcg->memsw_is_minimum = false;
}
mutex_unlock(&set_limit_mutex);
if (!ret)
break;
mem_cgroup_reclaim(memcg, GFP_KERNEL,
MEM_CGROUP_RECLAIM_NOSWAP |
MEM_CGROUP_RECLAIM_SHRINK);
curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
/* Usage is reduced ? */
if (curusage >= oldusage)
retry_count--;
else
oldusage = curusage;
}
if (!ret && enlarge)
memcg_oom_recover(memcg);
return ret;
}
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
gfp_t gfp_mask,
unsigned long *total_scanned)
{
unsigned long nr_reclaimed = 0;
struct mem_cgroup_per_zone *mz, *next_mz = NULL;
unsigned long reclaimed;
int loop = 0;
struct mem_cgroup_tree_per_zone *mctz;
unsigned long long excess;
unsigned long nr_scanned;
if (order > 0)
return 0;
mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
/*
* 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, zone,
gfp_mask, &nr_scanned);
nr_reclaimed += reclaimed;
*total_scanned += nr_scanned;
spin_lock(&mctz->lock);
/*
* If we failed to reclaim anything from this memory cgroup
* it is time to move on to the next cgroup
*/
next_mz = NULL;
if (!reclaimed) {
do {
/*
* Loop until we find yet another one.
*
* By the time we get the soft_limit lock
* again, someone might have aded the
* group back on the RB tree. Iterate to
* make sure we get a different mem.
* mem_cgroup_largest_soft_limit_node returns
* NULL if no other cgroup is present on
* the tree
*/
next_mz =
__mem_cgroup_largest_soft_limit_node(mctz);
if (next_mz == mz)
css_put(&next_mz->memcg->css);
else /* next_mz == NULL or other memcg */
break;
} while (1);
}
__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
excess = res_counter_soft_limit_excess(&mz->memcg->res);
/*
* 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->memcg, mz, mctz, excess);
spin_unlock(&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;
}
/**
* mem_cgroup_force_empty_list - clears LRU of a group
* @memcg: group to clear
* @node: NUMA node
* @zid: zone id
* @lru: lru to to clear
*
* Traverse a specified page_cgroup list and try to drop them all. This doesn't
* reclaim the pages page themselves - pages are moved to the parent (or root)
* group.
*/
static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
int node, int zid, enum lru_list lru)
{
struct lruvec *lruvec;
unsigned long flags;
struct list_head *list;
struct page *busy;
struct zone *zone;
zone = &NODE_DATA(node)->node_zones[zid];
lruvec = mem_cgroup_zone_lruvec(zone, memcg);
list = &lruvec->lists[lru];
busy = NULL;
do {
struct page_cgroup *pc;
struct page *page;
spin_lock_irqsave(&zone->lru_lock, flags);
if (list_empty(list)) {
spin_unlock_irqrestore(&zone->lru_lock, flags);
break;
}
page = list_entry(list->prev, struct page, lru);
if (busy == page) {
list_move(&page->lru, list);
busy = NULL;
spin_unlock_irqrestore(&zone->lru_lock, flags);
continue;
}
spin_unlock_irqrestore(&zone->lru_lock, flags);
pc = lookup_page_cgroup(page);
if (mem_cgroup_move_parent(page, pc, memcg)) {
/* found lock contention or "pc" is obsolete. */
busy = page;
cond_resched();
} else
busy = NULL;
} while (!list_empty(list));
}
/*
* make mem_cgroup's charge to be 0 if there is no task by moving
* all the charges and pages to the parent.
* This enables deleting this mem_cgroup.
*
* Caller is responsible for holding css reference on the memcg.
*/
static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
{
int node, zid;
u64 usage;
do {
/* This is for making all *used* pages to be on LRU. */
lru_add_drain_all();
drain_all_stock_sync(memcg);
mem_cgroup_start_move(memcg);
for_each_node_state(node, N_MEMORY) {
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
enum lru_list lru;
for_each_lru(lru) {
mem_cgroup_force_empty_list(memcg,
node, zid, lru);
}
}
}
mem_cgroup_end_move(memcg);
memcg_oom_recover(memcg);
cond_resched();
/*
* Kernel memory may not necessarily be trackable to a specific
* process. So they are not migrated, and therefore we can't
* expect their value to drop to 0 here.
* Having res filled up with kmem only is enough.
*
* This is a safety check because mem_cgroup_force_empty_list
* could have raced with mem_cgroup_replace_page_cache callers
* so the lru seemed empty but the page could have been added
* right after the check. RES_USAGE should be safe as we always
* charge before adding to the LRU.
*/
usage = res_counter_read_u64(&memcg->res, RES_USAGE) -
res_counter_read_u64(&memcg->kmem, RES_USAGE);
} while (usage > 0);
}
static inline bool memcg_has_children(struct mem_cgroup *memcg)
{
lockdep_assert_held(&memcg_create_mutex);
/*
* The lock does not prevent addition or deletion to the list
* of children, but it prevents a new child from being
* initialized based on this parent in css_online(), so it's
* enough to decide whether hierarchically inherited
* attributes can still be changed or not.
*/
return memcg->use_hierarchy &&
!list_empty(&memcg->css.cgroup->children);
}
/*
* Reclaims as many pages from the given memcg as possible and moves
* the rest to the parent.
*
* 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;
struct cgroup *cgrp = memcg->css.cgroup;
/* returns EBUSY if there is a task or if we come here twice. */
if (cgroup_has_tasks(cgrp) || !list_empty(&cgrp->children))
return -EBUSY;
/* we call try-to-free pages for make this cgroup empty */
lru_add_drain_all();
/* try to free all pages in this cgroup */
while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
int progress;
if (signal_pending(current))
return -EINTR;
progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
false);
if (!progress) {
nr_retries--;
/* maybe some writeback is necessary */
congestion_wait(BLK_RW_ASYNC, HZ/10);
}
}
lru_add_drain();
mem_cgroup_reparent_charges(memcg);
return 0;
}
static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css,
unsigned int event)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
if (mem_cgroup_is_root(memcg))
return -EINVAL;
return mem_cgroup_force_empty(memcg);
}
static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return mem_cgroup_from_css(css)->use_hierarchy;
}
static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
int retval = 0;
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css));
mutex_lock(&memcg_create_mutex);
if (memcg->use_hierarchy == val)
goto out;
/*
* If parent's use_hierarchy is set, we can't make any modifications
* in the child subtrees. If it is unset, then the change can
* occur, provided the current cgroup has no children.
*
* For the root cgroup, parent_mem is NULL, we allow value to be
* set if there are no children.
*/
if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
(val == 1 || val == 0)) {
if (list_empty(&memcg->css.cgroup->children))
memcg->use_hierarchy = val;
else
retval = -EBUSY;
} else
retval = -EINVAL;
out:
mutex_unlock(&memcg_create_mutex);
return retval;
}
static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx)
{
struct mem_cgroup *iter;
long val = 0;
/* Per-cpu values can be negative, use a signed accumulator */
for_each_mem_cgroup_tree(iter, memcg)
val += mem_cgroup_read_stat(iter, idx);
if (val < 0) /* race ? */
val = 0;
return val;
}
static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
{
u64 val;
if (!mem_cgroup_is_root(memcg)) {
if (!swap)
return res_counter_read_u64(&memcg->res, RES_USAGE);
else
return res_counter_read_u64(&memcg->memsw, RES_USAGE);
}
/*
* Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
* as well as in MEM_CGROUP_STAT_RSS_HUGE.
*/
val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
if (swap)
val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
return val << PAGE_SHIFT;
}
static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
u64 val;
int name;
enum res_type type;
type = MEMFILE_TYPE(cft->private);
name = MEMFILE_ATTR(cft->private);
switch (type) {
case _MEM:
if (name == RES_USAGE)
val = mem_cgroup_usage(memcg, false);
else
val = res_counter_read_u64(&memcg->res, name);
break;
case _MEMSWAP:
if (name == RES_USAGE)
val = mem_cgroup_usage(memcg, true);
else
val = res_counter_read_u64(&memcg->memsw, name);
break;
case _KMEM:
val = res_counter_read_u64(&memcg->kmem, name);
break;
default:
BUG();
}
return val;
}
#ifdef CONFIG_MEMCG_KMEM
/* should be called with activate_kmem_mutex held */
static int __memcg_activate_kmem(struct mem_cgroup *memcg,
unsigned long long limit)
{
int err = 0;
int memcg_id;
if (memcg_kmem_is_active(memcg))
return 0;
/*
* We are going to allocate memory for data shared by all memory
* cgroups so let's stop accounting here.
*/
memcg_stop_kmem_account();
/*
* For simplicity, we won't allow this to be disabled. It also can't
* be changed if the cgroup has children already, or if tasks had
* already joined.
*
* If tasks join before we set the limit, a person looking at
* kmem.usage_in_bytes will have no way to determine when it took
* place, which makes the value quite meaningless.
*
* After it first became limited, changes in the value of the limit are
* of course permitted.
*/
mutex_lock(&memcg_create_mutex);
if (cgroup_has_tasks(memcg->css.cgroup) || memcg_has_children(memcg))
err = -EBUSY;
mutex_unlock(&memcg_create_mutex);
if (err)
goto out;
memcg_id = ida_simple_get(&kmem_limited_groups,
0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
if (memcg_id < 0) {
err = memcg_id;
goto out;
}
/*
* Make sure we have enough space for this cgroup in each root cache's
* memcg_params.
*/
err = memcg_update_all_caches(memcg_id + 1);
if (err)
goto out_rmid;
memcg->kmemcg_id = memcg_id;
INIT_LIST_HEAD(&memcg->memcg_slab_caches);
mutex_init(&memcg->slab_caches_mutex);
/*
* We couldn't have accounted to this cgroup, because it hasn't got the
* active bit set yet, so this should succeed.
*/
err = res_counter_set_limit(&memcg->kmem, limit);
VM_BUG_ON(err);
static_key_slow_inc(&memcg_kmem_enabled_key);
/*
* Setting the active bit after enabling static branching will
* guarantee no one starts accounting before all call sites are
* patched.
*/
memcg_kmem_set_active(memcg);
out:
memcg_resume_kmem_account();
return err;
out_rmid:
ida_simple_remove(&kmem_limited_groups, memcg_id);
goto out;
}
static int memcg_activate_kmem(struct mem_cgroup *memcg,
unsigned long long limit)
{
int ret;
mutex_lock(&activate_kmem_mutex);
ret = __memcg_activate_kmem(memcg, limit);
mutex_unlock(&activate_kmem_mutex);
return ret;
}
static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
int ret;
if (!memcg_kmem_is_active(memcg))
ret = memcg_activate_kmem(memcg, val);
else
ret = res_counter_set_limit(&memcg->kmem, val);
return ret;
}
static int memcg_propagate_kmem(struct mem_cgroup *memcg)
{
int ret = 0;
struct mem_cgroup *parent = parent_mem_cgroup(memcg);
if (!parent)
return 0;
mutex_lock(&activate_kmem_mutex);
/*
* If the parent cgroup is not kmem-active now, it cannot be activated
* after this point, because it has at least one child already.
*/
if (memcg_kmem_is_active(parent))
ret = __memcg_activate_kmem(memcg, RES_COUNTER_MAX);
mutex_unlock(&activate_kmem_mutex);
return ret;
}
#else
static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
return -EINVAL;
}
#endif /* CONFIG_MEMCG_KMEM */
/*
* The user of this function is...
* RES_LIMIT.
*/
static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft,
char *buffer)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
enum res_type type;
int name;
unsigned long long val;
int ret;
type = MEMFILE_TYPE(cft->private);
name = MEMFILE_ATTR(cft->private);
switch (name) {
case RES_LIMIT:
if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
ret = -EINVAL;
break;
}
/* This function does all necessary parse...reuse it */
ret = res_counter_memparse_write_strategy(buffer, &val);
if (ret)
break;
if (type == _MEM)
ret = mem_cgroup_resize_limit(memcg, val);
else if (type == _MEMSWAP)
ret = mem_cgroup_resize_memsw_limit(memcg, val);
else if (type == _KMEM)
ret = memcg_update_kmem_limit(memcg, val);
else
return -EINVAL;
break;
case RES_SOFT_LIMIT:
ret = res_counter_memparse_write_strategy(buffer, &val);
if (ret)
break;
/*
* For memsw, soft limits are hard to implement in terms
* of semantics, for now, we support soft limits for
* control without swap
*/
if (type == _MEM)
ret = res_counter_set_soft_limit(&memcg->res, val);
else
ret = -EINVAL;
break;
default:
ret = -EINVAL; /* should be BUG() ? */
break;
}
return ret;
}
static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
unsigned long long *mem_limit, unsigned long long *memsw_limit)
{
unsigned long long min_limit, min_memsw_limit, tmp;
min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
if (!memcg->use_hierarchy)
goto out;
while (css_parent(&memcg->css)) {
memcg = mem_cgroup_from_css(css_parent(&memcg->css));
if (!memcg->use_hierarchy)
break;
tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
min_limit = min(min_limit, tmp);
tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
min_memsw_limit = min(min_memsw_limit, tmp);
}
out:
*mem_limit = min_limit;
*memsw_limit = min_memsw_limit;
}
static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
int name;
enum res_type type;
type = MEMFILE_TYPE(event);
name = MEMFILE_ATTR(event);
switch (name) {
case RES_MAX_USAGE:
if (type == _MEM)
res_counter_reset_max(&memcg->res);
else if (type == _MEMSWAP)
res_counter_reset_max(&memcg->memsw);
else if (type == _KMEM)
res_counter_reset_max(&memcg->kmem);
else
return -EINVAL;
break;
case RES_FAILCNT:
if (type == _MEM)
res_counter_reset_failcnt(&memcg->res);
else if (type == _MEMSWAP)
res_counter_reset_failcnt(&memcg->memsw);
else if (type == _KMEM)
res_counter_reset_failcnt(&memcg->kmem);
else
return -EINVAL;
break;
}
return 0;
}
static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return mem_cgroup_from_css(css)->move_charge_at_immigrate;
}
#ifdef CONFIG_MMU
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
if (val >= (1 << NR_MOVE_TYPE))
return -EINVAL;
/*
* No kind of locking is needed in here, because ->can_attach() will
* check this value once in the beginning of the process, and then carry
* on with stale data. This means that changes to this value will only
* affect task migrations starting after the change.
*/
memcg->move_charge_at_immigrate = val;
return 0;
}
#else
static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
return -ENOSYS;
}
#endif
#ifdef CONFIG_NUMA
static int memcg_numa_stat_show(struct seq_file *m, void *v)
{
struct numa_stat {
const char *name;
unsigned int lru_mask;
};
static const struct numa_stat stats[] = {
{ "total", LRU_ALL },
{ "file", LRU_ALL_FILE },
{ "anon", LRU_ALL_ANON },
{ "unevictable", BIT(LRU_UNEVICTABLE) },
};
const struct numa_stat *stat;
int nid;
unsigned long nr;
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask);
seq_printf(m, "%s=%lu", stat->name, nr);
for_each_node_state(nid, N_MEMORY) {
nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
stat->lru_mask);
seq_printf(m, " N%d=%lu", nid, nr);
}
seq_putc(m, '\n');
}
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
struct mem_cgroup *iter;
nr = 0;
for_each_mem_cgroup_tree(iter, memcg)
nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask);
seq_printf(m, "hierarchical_%s=%lu", stat->name, nr);
for_each_node_state(nid, N_MEMORY) {
nr = 0;
for_each_mem_cgroup_tree(iter, memcg)
nr += mem_cgroup_node_nr_lru_pages(
iter, nid, stat->lru_mask);
seq_printf(m, " N%d=%lu", nid, nr);
}
seq_putc(m, '\n');
}
return 0;
}
#endif /* CONFIG_NUMA */
static inline void mem_cgroup_lru_names_not_uptodate(void)
{
BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
}
static int memcg_stat_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
struct mem_cgroup *mi;
unsigned int i;
for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
continue;
seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i],
mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
}
for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++)
seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i],
mem_cgroup_read_events(memcg, i));
for (i = 0; i < NR_LRU_LISTS; i++)
seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i],
mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);
/* Hierarchical information */
{
unsigned long long limit, memsw_limit;
memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
seq_printf(m, "hierarchical_memory_limit %llu\n", limit);
if (do_swap_account)
seq_printf(m, "hierarchical_memsw_limit %llu\n",
memsw_limit);
}
for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
long long val = 0;
if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
continue;
for_each_mem_cgroup_tree(mi, memcg)
val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE;
seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val);
}
for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
unsigned long long val = 0;
for_each_mem_cgroup_tree(mi, memcg)
val += mem_cgroup_read_events(mi, i);
seq_printf(m, "total_%s %llu\n",
mem_cgroup_events_names[i], val);
}
for (i = 0; i < NR_LRU_LISTS; i++) {
unsigned long long val = 0;
for_each_mem_cgroup_tree(mi, memcg)
val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE;
seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val);
}
#ifdef CONFIG_DEBUG_VM
{
int nid, zid;
struct mem_cgroup_per_zone *mz;
struct zone_reclaim_stat *rstat;
unsigned long recent_rotated[2] = {0, 0};
unsigned long recent_scanned[2] = {0, 0};
for_each_online_node(nid)
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
mz = mem_cgroup_zoneinfo(memcg, nid, zid);
rstat = &mz->lruvec.reclaim_stat;
recent_rotated[0] += rstat->recent_rotated[0];
recent_rotated[1] += rstat->recent_rotated[1];
recent_scanned[0] += rstat->recent_scanned[0];
recent_scanned[1] += rstat->recent_scanned[1];
}
seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]);
seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]);
seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]);
seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]);
}
#endif
return 0;
}
static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
return mem_cgroup_swappiness(memcg);
}
static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
if (val > 100 || !parent)
return -EINVAL;
mutex_lock(&memcg_create_mutex);
/* If under hierarchy, only empty-root can set this value */
if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
mutex_unlock(&memcg_create_mutex);
return -EINVAL;
}
memcg->swappiness = val;
mutex_unlock(&memcg_create_mutex);
return 0;
}
static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
{
struct mem_cgroup_threshold_ary *t;
u64 usage;
int i;
rcu_read_lock();
if (!swap)
t = rcu_dereference(memcg->thresholds.primary);
else
t = rcu_dereference(memcg->memsw_thresholds.primary);
if (!t)
goto unlock;
usage = mem_cgroup_usage(memcg, swap);
/*
* current_threshold points to threshold just below or equal to usage.
* If it's not true, a threshold was crossed after last
* call of __mem_cgroup_threshold().
*/
i = t->current_threshold;
/*
* Iterate backward over array of thresholds starting from
* current_threshold and check if a threshold is crossed.
* If none of thresholds below usage is crossed, we read
* only one element of the array here.
*/
for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
eventfd_signal(t->entries[i].eventfd, 1);
/* i = current_threshold + 1 */
i++;
/*
* Iterate forward over array of thresholds starting from
* current_threshold+1 and check if a threshold is crossed.
* If none of thresholds above usage is crossed, we read
* only one element of the array here.
*/
for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
eventfd_signal(t->entries[i].eventfd, 1);
/* Update current_threshold */
t->current_threshold = i - 1;
unlock:
rcu_read_unlock();
}
static void mem_cgroup_threshold(struct mem_cgroup *memcg)
{
while (memcg) {
__mem_cgroup_threshold(memcg, false);
if (do_swap_account)
__mem_cgroup_threshold(memcg, true);
memcg = parent_mem_cgroup(memcg);
}
}
static int compare_thresholds(const void *a, const void *b)
{
const struct mem_cgroup_threshold *_a = a;
const struct mem_cgroup_threshold *_b = b;
if (_a->threshold > _b->threshold)
return 1;
if (_a->threshold < _b->threshold)
return -1;
return 0;
}
static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
{
struct mem_cgroup_eventfd_list *ev;
list_for_each_entry(ev, &memcg->oom_notify, list)
eventfd_signal(ev->eventfd, 1);
return 0;
}
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
for_each_mem_cgroup_tree(iter, memcg)
mem_cgroup_oom_notify_cb(iter);
}
static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args, enum res_type type)
{
struct mem_cgroup_thresholds *thresholds;
struct mem_cgroup_threshold_ary *new;
u64 threshold, usage;
int i, size, ret;
ret = res_counter_memparse_write_strategy(args, &threshold);
if (ret)
return ret;
mutex_lock(&memcg->thresholds_lock);
if (type == _MEM)
thresholds = &memcg->thresholds;
else if (type == _MEMSWAP)
thresholds = &memcg->memsw_thresholds;
else
BUG();
usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
/* Check if a threshold crossed before adding a new one */
if (thresholds->primary)
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
size = thresholds->primary ? thresholds->primary->size + 1 : 1;
/* Allocate memory for new array of thresholds */
new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
GFP_KERNEL);
if (!new) {
ret = -ENOMEM;
goto unlock;
}
new->size = size;
/* Copy thresholds (if any) to new array */
if (thresholds->primary) {
memcpy(new->entries, thresholds->primary->entries, (size - 1) *
sizeof(struct mem_cgroup_threshold));
}
/* Add new threshold */
new->entries[size - 1].eventfd = eventfd;
new->entries[size - 1].threshold = threshold;
/* Sort thresholds. Registering of new threshold isn't time-critical */
sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
compare_thresholds, NULL);
/* Find current threshold */
new->current_threshold = -1;
for (i = 0; i < size; i++) {
if (new->entries[i].threshold <= usage) {
/*
* new->current_threshold will not be used until
* rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++new->current_threshold;
} else
break;
}
/* Free old spare buffer and save old primary buffer as spare */
kfree(thresholds->spare);
thresholds->spare = thresholds->primary;
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
synchronize_rcu();
unlock:
mutex_unlock(&memcg->thresholds_lock);
return ret;
}
static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args)
{
return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
}
static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args)
{
return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
}
static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, enum res_type type)
{
struct mem_cgroup_thresholds *thresholds;
struct mem_cgroup_threshold_ary *new;
u64 usage;
int i, j, size;
mutex_lock(&memcg->thresholds_lock);
if (type == _MEM)
thresholds = &memcg->thresholds;
else if (type == _MEMSWAP)
thresholds = &memcg->memsw_thresholds;
else
BUG();
if (!thresholds->primary)
goto unlock;
usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
/* Check if a threshold crossed before removing */
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
/* Calculate new number of threshold */
size = 0;
for (i = 0; i < thresholds->primary->size; i++) {
if (thresholds->primary->entries[i].eventfd != eventfd)
size++;
}
new = thresholds->spare;
/* Set thresholds array to NULL if we don't have thresholds */
if (!size) {
kfree(new);
new = NULL;
goto swap_buffers;
}
new->size = size;
/* Copy thresholds and find current threshold */
new->current_threshold = -1;
for (i = 0, j = 0; i < thresholds->primary->size; i++) {
if (thresholds->primary->entries[i].eventfd == eventfd)
continue;
new->entries[j] = thresholds->primary->entries[i];
if (new->entries[j].threshold <= usage) {
/*
* new->current_threshold will not be used
* until rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++new->current_threshold;
}
j++;
}
swap_buffers:
/* Swap primary and spare array */
thresholds->spare = thresholds->primary;
/* If all events are unregistered, free the spare array */
if (!new) {
kfree(thresholds->spare);
thresholds->spare = NULL;
}
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
synchronize_rcu();
unlock:
mutex_unlock(&memcg->thresholds_lock);
}
static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd)
{
return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
}
static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd)
{
return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
}
static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args)
{
struct mem_cgroup_eventfd_list *event;
event = kmalloc(sizeof(*event), GFP_KERNEL);
if (!event)
return -ENOMEM;
spin_lock(&memcg_oom_lock);
event->eventfd = eventfd;
list_add(&event->list, &memcg->oom_notify);
/* already in OOM ? */
if (atomic_read(&memcg->under_oom))
eventfd_signal(eventfd, 1);
spin_unlock(&memcg_oom_lock);
return 0;
}
static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd)
{
struct mem_cgroup_eventfd_list *ev, *tmp;
spin_lock(&memcg_oom_lock);
list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
if (ev->eventfd == eventfd) {
list_del(&ev->list);
kfree(ev);
}
}
spin_unlock(&memcg_oom_lock);
}
static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf));
seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
seq_printf(sf, "under_oom %d\n", (bool)atomic_read(&memcg->under_oom));
return 0;
}
static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
/* cannot set to root cgroup and only 0 and 1 are allowed */
if (!parent || !((val == 0) || (val == 1)))
return -EINVAL;
mutex_lock(&memcg_create_mutex);
/* oom-kill-disable is a flag for subhierarchy. */
if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
mutex_unlock(&memcg_create_mutex);
return -EINVAL;
}
memcg->oom_kill_disable = val;
if (!val)
memcg_oom_recover(memcg);
mutex_unlock(&memcg_create_mutex);
return 0;
}
#ifdef CONFIG_MEMCG_KMEM
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
{
int ret;
memcg->kmemcg_id = -1;
ret = memcg_propagate_kmem(memcg);
if (ret)
return ret;
return mem_cgroup_sockets_init(memcg, ss);
}
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
{
mem_cgroup_sockets_destroy(memcg);
}
static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
{
if (!memcg_kmem_is_active(memcg))
return;
/*
* kmem charges can outlive the cgroup. In the case of slab
* pages, for instance, a page contain objects from various
* processes. As we prevent from taking a reference for every
* such allocation we have to be careful when doing uncharge
* (see memcg_uncharge_kmem) and here during offlining.
*
* The idea is that that only the _last_ uncharge which sees
* the dead memcg will drop the last reference. An additional
* reference is taken here before the group is marked dead
* which is then paired with css_put during uncharge resp. here.
*
* Although this might sound strange as this path is called from
* css_offline() when the referencemight have dropped down to 0
* and shouldn't be incremented anymore (css_tryget would fail)
* we do not have other options because of the kmem allocations
* lifetime.
*/
css_get(&memcg->css);
memcg_kmem_mark_dead(memcg);
if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0)
return;
if (memcg_kmem_test_and_clear_dead(memcg))
css_put(&memcg->css);
}
#else
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
{
return 0;
}
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
{
}
static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
{
}
#endif
/*
* DO NOT USE IN NEW FILES.
*
* "cgroup.event_control" implementation.
*
* This is way over-engineered. It tries to support fully configurable
* events for each user. Such level of flexibility is completely
* unnecessary especially in the light of the planned unified hierarchy.
*
* Please deprecate this and replace with something simpler if at all
* possible.
*/
/*
* Unregister event and free resources.
*
* Gets called from workqueue.
*/
static void memcg_event_remove(struct work_struct *work)
{
struct mem_cgroup_event *event =
container_of(work, struct mem_cgroup_event, remove);
struct mem_cgroup *memcg = event->memcg;
remove_wait_queue(event->wqh, &event->wait);
event->unregister_event(memcg, event->eventfd);
/* Notify userspace the event is going away. */
eventfd_signal(event->eventfd, 1);
eventfd_ctx_put(event->eventfd);
kfree(event);
css_put(&memcg->css);
}
/*
* Gets called on POLLHUP on eventfd when user closes it.
*
* Called with wqh->lock held and interrupts disabled.
*/
static int memcg_event_wake(wait_queue_t *wait, unsigned mode,
int sync, void *key)
{
struct mem_cgroup_event *event =
container_of(wait, struct mem_cgroup_event, wait);
struct mem_cgroup *memcg = event->memcg;
unsigned long flags = (unsigned long)key;
if (flags & POLLHUP) {
/*
* If the event has been detached at cgroup removal, we
* can simply return knowing the other side will cleanup
* for us.
*
* We can't race against event freeing since the other
* side will require wqh->lock via remove_wait_queue(),
* which we hold.
*/
spin_lock(&memcg->event_list_lock);
if (!list_empty(&event->list)) {
list_del_init(&event->list);
/*
* We are in atomic context, but cgroup_event_remove()
* may sleep, so we have to call it in workqueue.
*/
schedule_work(&event->remove);
}
spin_unlock(&memcg->event_list_lock);
}
return 0;
}
static void memcg_event_ptable_queue_proc(struct file *file,
wait_queue_head_t *wqh, poll_table *pt)
{
struct mem_cgroup_event *event =
container_of(pt, struct mem_cgroup_event, pt);
event->wqh = wqh;
add_wait_queue(wqh, &event->wait);
}
/*
* DO NOT USE IN NEW FILES.
*
* Parse input and register new cgroup event handler.
*
* Input must be in format '<event_fd> <control_fd> <args>'.
* Interpretation of args is defined by control file implementation.
*/
static int memcg_write_event_control(struct cgroup_subsys_state *css,
struct cftype *cft, char *buffer)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup_event *event;
struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
struct fd efile;
struct fd cfile;
const char *name;
char *endp;
int ret;
efd = simple_strtoul(buffer, &endp, 10);
if (*endp != ' ')
return -EINVAL;
buffer = endp + 1;
cfd = simple_strtoul(buffer, &endp, 10);
if ((*endp != ' ') && (*endp != '\0'))
return -EINVAL;
buffer = endp + 1;
event = kzalloc(sizeof(*event), GFP_KERNEL);
if (!event)
return -ENOMEM;
event->memcg = memcg;
INIT_LIST_HEAD(&event->list);
init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
init_waitqueue_func_entry(&event->wait, memcg_event_wake);
INIT_WORK(&event->remove, memcg_event_remove);
efile = fdget(efd);
if (!efile.file) {
ret = -EBADF;
goto out_kfree;
}
event->eventfd = eventfd_ctx_fileget(efile.file);
if (IS_ERR(event->eventfd)) {
ret = PTR_ERR(event->eventfd);
goto out_put_efile;
}
cfile = fdget(cfd);
if (!cfile.file) {
ret = -EBADF;
goto out_put_eventfd;
}
/* the process need read permission on control file */
/* AV: shouldn't we check that it's been opened for read instead? */
ret = inode_permission(file_inode(cfile.file), MAY_READ);
if (ret < 0)
goto out_put_cfile;
/*
* Determine the event callbacks and set them in @event. This used
* to be done via struct cftype but cgroup core no longer knows
* about these events. The following is crude but the whole thing
* is for compatibility anyway.
*
* DO NOT ADD NEW FILES.
*/
name = cfile.file->f_dentry->d_name.name;
if (!strcmp(name, "memory.usage_in_bytes")) {
event->register_event = mem_cgroup_usage_register_event;
event->unregister_event = mem_cgroup_usage_unregister_event;
} else if (!strcmp(name, "memory.oom_control")) {
event->register_event = mem_cgroup_oom_register_event;
event->unregister_event = mem_cgroup_oom_unregister_event;
} else if (!strcmp(name, "memory.pressure_level")) {
event->register_event = vmpressure_register_event;
event->unregister_event = vmpressure_unregister_event;
} else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
event->register_event = memsw_cgroup_usage_register_event;
event->unregister_event = memsw_cgroup_usage_unregister_event;
} else {
ret = -EINVAL;
goto out_put_cfile;
}
/*
* Verify @cfile should belong to @css. Also, remaining events are
* automatically removed on cgroup destruction but the removal is
* asynchronous, so take an extra ref on @css.
*/
cfile_css = css_tryget_from_dir(cfile.file->f_dentry->d_parent,
&memory_cgrp_subsys);
ret = -EINVAL;
if (IS_ERR(cfile_css))
goto out_put_cfile;
if (cfile_css != css) {
css_put(cfile_css);
goto out_put_cfile;
}
ret = event->register_event(memcg, event->eventfd, buffer);
if (ret)
goto out_put_css;
efile.file->f_op->poll(efile.file, &event->pt);
spin_lock(&memcg->event_list_lock);
list_add(&event->list, &memcg->event_list);
spin_unlock(&memcg->event_list_lock);
fdput(cfile);
fdput(efile);
return 0;
out_put_css:
css_put(css);
out_put_cfile:
fdput(cfile);
out_put_eventfd:
eventfd_ctx_put(event->eventfd);
out_put_efile:
fdput(efile);
out_kfree:
kfree(event);
return ret;
}
static struct cftype mem_cgroup_files[] = {
{
.name = "usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
.write_string = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "soft_limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
.write_string = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "failcnt",
.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "stat",
.seq_show = memcg_stat_show,
},
{
.name = "force_empty",
.trigger = mem_cgroup_force_empty_write,
},
{
.name = "use_hierarchy",
.flags = CFTYPE_INSANE,
.write_u64 = mem_cgroup_hierarchy_write,
.read_u64 = mem_cgroup_hierarchy_read,
},
{
.name = "cgroup.event_control", /* XXX: for compat */
.write_string = memcg_write_event_control,
.flags = CFTYPE_NO_PREFIX,
.mode = S_IWUGO,
},
{
.name = "swappiness",
.read_u64 = mem_cgroup_swappiness_read,
.write_u64 = mem_cgroup_swappiness_write,
},
{
.name = "move_charge_at_immigrate",
.read_u64 = mem_cgroup_move_charge_read,
.write_u64 = mem_cgroup_move_charge_write,
},
{
.name = "oom_control",
.seq_show = mem_cgroup_oom_control_read,
.write_u64 = mem_cgroup_oom_control_write,
.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
},
{
.name = "pressure_level",
},
#ifdef CONFIG_NUMA
{
.name = "numa_stat",
.seq_show = memcg_numa_stat_show,
},
#endif
#ifdef CONFIG_MEMCG_KMEM
{
.name = "kmem.limit_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
.write_string = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.failcnt",
.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
#ifdef CONFIG_SLABINFO
{
.name = "kmem.slabinfo",
.seq_show = mem_cgroup_slabinfo_read,
},
#endif
#endif
{ }, /* terminate */
};
#ifdef CONFIG_MEMCG_SWAP
static struct cftype memsw_cgroup_files[] = {
{
.name = "memsw.usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
.write_string = mem_cgroup_write,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.failcnt",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
.trigger = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{ }, /* terminate */
};
#endif
static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
{
struct mem_cgroup_per_node *pn;
struct mem_cgroup_per_zone *mz;
int zone, tmp = node;
/*
* This routine is called against possible nodes.
* But it's BUG to call kmalloc() against offline node.
*
* TODO: this routine can waste much memory for nodes which will
* never be onlined. It's better to use memory hotplug callback
* function.
*/
if (!node_state(node, N_NORMAL_MEMORY))
tmp = -1;
pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
if (!pn)
return 1;
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
mz = &pn->zoneinfo[zone];
lruvec_init(&mz->lruvec);
mz->usage_in_excess = 0;
mz->on_tree = false;
mz->memcg = memcg;
}
memcg->nodeinfo[node] = pn;
return 0;
}
static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
{
kfree(memcg->nodeinfo[node]);
}
static struct mem_cgroup *mem_cgroup_alloc(void)
{
struct mem_cgroup *memcg;
size_t size;
size = sizeof(struct mem_cgroup);
size += nr_node_ids * sizeof(struct mem_cgroup_per_node *);
memcg = kzalloc(size, GFP_KERNEL);
if (!memcg)
return NULL;
memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
if (!memcg->stat)
goto out_free;
spin_lock_init(&memcg->pcp_counter_lock);
return memcg;
out_free:
kfree(memcg);
return NULL;
}
/*
* At destroying mem_cgroup, references from swap_cgroup can remain.
* (scanning all at force_empty is too costly...)
*
* Instead of clearing all references at force_empty, we remember
* the number of reference from swap_cgroup and free mem_cgroup when
* it goes down to 0.
*
* Removal of cgroup itself succeeds regardless of refs from swap.
*/
static void __mem_cgroup_free(struct mem_cgroup *memcg)
{
int node;
mem_cgroup_remove_from_trees(memcg);
for_each_node(node)
free_mem_cgroup_per_zone_info(memcg, node);
free_percpu(memcg->stat);
/*
* We need to make sure that (at least for now), the jump label
* destruction code runs outside of the cgroup lock. This is because
* get_online_cpus(), which is called from the static_branch update,
* can't be called inside the cgroup_lock. cpusets are the ones
* enforcing this dependency, so if they ever change, we might as well.
*
* schedule_work() will guarantee this happens. Be careful if you need
* to move this code around, and make sure it is outside
* the cgroup_lock.
*/
disarm_static_keys(memcg);
kfree(memcg);
}
/*
* Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
*/
struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
{
if (!memcg->res.parent)
return NULL;
return mem_cgroup_from_res_counter(memcg->res.parent, res);
}
EXPORT_SYMBOL(parent_mem_cgroup);
static void __init mem_cgroup_soft_limit_tree_init(void)
{
struct mem_cgroup_tree_per_node *rtpn;
struct mem_cgroup_tree_per_zone *rtpz;
int tmp, node, zone;
for_each_node(node) {
tmp = node;
if (!node_state(node, N_NORMAL_MEMORY))
tmp = -1;
rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
BUG_ON(!rtpn);
soft_limit_tree.rb_tree_per_node[node] = rtpn;
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
rtpz = &rtpn->rb_tree_per_zone[zone];
rtpz->rb_root = RB_ROOT;
spin_lock_init(&rtpz->lock);
}
}
}
static struct cgroup_subsys_state * __ref
mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct mem_cgroup *memcg;
long error = -ENOMEM;
int node;
memcg = mem_cgroup_alloc();
if (!memcg)
return ERR_PTR(error);
for_each_node(node)
if (alloc_mem_cgroup_per_zone_info(memcg, node))
goto free_out;
/* root ? */
if (parent_css == NULL) {
root_mem_cgroup = memcg;
res_counter_init(&memcg->res, NULL);
res_counter_init(&memcg->memsw, NULL);
res_counter_init(&memcg->kmem, NULL);
}
memcg->last_scanned_node = MAX_NUMNODES;
INIT_LIST_HEAD(&memcg->oom_notify);
memcg->move_charge_at_immigrate = 0;
mutex_init(&memcg->thresholds_lock);
spin_lock_init(&memcg->move_lock);
vmpressure_init(&memcg->vmpressure);
INIT_LIST_HEAD(&memcg->event_list);
spin_lock_init(&memcg->event_list_lock);
return &memcg->css;
free_out:
__mem_cgroup_free(memcg);
return ERR_PTR(error);
}
static int
mem_cgroup_css_online(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css));
if (css->cgroup->id > MEM_CGROUP_ID_MAX)
return -ENOSPC;
if (!parent)
return 0;
mutex_lock(&memcg_create_mutex);
memcg->use_hierarchy = parent->use_hierarchy;
memcg->oom_kill_disable = parent->oom_kill_disable;
memcg->swappiness = mem_cgroup_swappiness(parent);
if (parent->use_hierarchy) {
res_counter_init(&memcg->res, &parent->res);
res_counter_init(&memcg->memsw, &parent->memsw);
res_counter_init(&memcg->kmem, &parent->kmem);
/*
* No need to take a reference to the parent because cgroup
* core guarantees its existence.
*/
} else {
res_counter_init(&memcg->res, NULL);
res_counter_init(&memcg->memsw, NULL);
res_counter_init(&memcg->kmem, NULL);
/*
* Deeper hierachy with use_hierarchy == false doesn't make
* much sense so let cgroup subsystem know about this
* unfortunate state in our controller.
*/
if (parent != root_mem_cgroup)
memory_cgrp_subsys.broken_hierarchy = true;
}
mutex_unlock(&memcg_create_mutex);
return memcg_init_kmem(memcg, &memory_cgrp_subsys);
}
/*
* Announce all parents that a group from their hierarchy is gone.
*/
static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg)
{
struct mem_cgroup *parent = memcg;
while ((parent = parent_mem_cgroup(parent)))
mem_cgroup_iter_invalidate(parent);
/*
* if the root memcg is not hierarchical we have to check it
* explicitely.
*/
if (!root_mem_cgroup->use_hierarchy)
mem_cgroup_iter_invalidate(root_mem_cgroup);
}
static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup_event *event, *tmp;
struct cgroup_subsys_state *iter;
/*
* Unregister events and notify userspace.
* Notify userspace about cgroup removing only after rmdir of cgroup
* directory to avoid race between userspace and kernelspace.
*/
spin_lock(&memcg->event_list_lock);
list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
list_del_init(&event->list);
schedule_work(&event->remove);
}
spin_unlock(&memcg->event_list_lock);
kmem_cgroup_css_offline(memcg);
mem_cgroup_invalidate_reclaim_iterators(memcg);
/*
* This requires that offlining is serialized. Right now that is
* guaranteed because css_killed_work_fn() holds the cgroup_mutex.
*/
css_for_each_descendant_post(iter, css)
mem_cgroup_reparent_charges(mem_cgroup_from_css(iter));
mem_cgroup_destroy_all_caches(memcg);
vmpressure_cleanup(&memcg->vmpressure);
}
static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
/*
* XXX: css_offline() would be where we should reparent all
* memory to prepare the cgroup for destruction. However,
* memcg does not do css_tryget() and res_counter charging
* under the same RCU lock region, which means that charging
* could race with offlining. Offlining only happens to
* cgroups with no tasks in them but charges can show up
* without any tasks from the swapin path when the target
* memcg is looked up from the swapout record and not from the
* current task as it usually is. A race like this can leak
* charges and put pages with stale cgroup pointers into
* circulation:
*
* #0 #1
* lookup_swap_cgroup_id()
* rcu_read_lock()
* mem_cgroup_lookup()
* css_tryget()
* rcu_read_unlock()
* disable css_tryget()
* call_rcu()
* offline_css()
* reparent_charges()
* res_counter_charge()
* css_put()
* css_free()
* pc->mem_cgroup = dead memcg
* add page to lru
*
* The bulk of the charges are still moved in offline_css() to
* avoid pinning a lot of pages in case a long-term reference
* like a swapout record is deferring the css_free() to long
* after offlining. But this makes sure we catch any charges
* made after offlining:
*/
mem_cgroup_reparent_charges(memcg);
memcg_destroy_kmem(memcg);
__mem_cgroup_free(memcg);
}
#ifdef CONFIG_MMU
/* Handlers for move charge at task migration. */
#define PRECHARGE_COUNT_AT_ONCE 256
static int mem_cgroup_do_precharge(unsigned long count)
{
int ret = 0;
int batch_count = PRECHARGE_COUNT_AT_ONCE;
struct mem_cgroup *memcg = mc.to;
if (mem_cgroup_is_root(memcg)) {
mc.precharge += count;
/* we don't need css_get for root */
return ret;
}
/* try to charge at once */
if (count > 1) {
struct res_counter *dummy;
/*
* "memcg" cannot be under rmdir() because we've already checked
* by cgroup_lock_live_cgroup() that it is not removed and we
* are still under the same cgroup_mutex. So we can postpone
* css_get().
*/
if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy))
goto one_by_one;
if (do_swap_account && res_counter_charge(&memcg->memsw,
PAGE_SIZE * count, &dummy)) {
res_counter_uncharge(&memcg->res, PAGE_SIZE * count);
goto one_by_one;
}
mc.precharge += count;
return ret;
}
one_by_one:
/* fall back to one by one charge */
while (count--) {
if (signal_pending(current)) {
ret = -EINTR;
break;
}
if (!batch_count--) {
batch_count = PRECHARGE_COUNT_AT_ONCE;
cond_resched();
}
ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
if (ret)
/* mem_cgroup_clear_mc() will do uncharge later */
return ret;
mc.precharge++;
}
return ret;
}
/**
* get_mctgt_type - get target type of moving charge
* @vma: the vma the pte to be checked belongs
* @addr: the address corresponding to the pte to be checked
* @ptent: the pte to be checked
* @target: the pointer the target page or swap ent will be stored(can be NULL)
*
* Returns
* 0(MC_TARGET_NONE): if the pte is not a target for move charge.
* 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
* move charge. if @target is not NULL, the page is stored in target->page
* with extra refcnt got(Callers should handle it).
* 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
* target for charge migration. if @target is not NULL, the entry is stored
* in target->ent.
*
* Called with pte lock held.
*/
union mc_target {
struct page *page;
swp_entry_t ent;
};
enum mc_target_type {
MC_TARGET_NONE = 0,
MC_TARGET_PAGE,
MC_TARGET_SWAP,
};
static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent)
{
struct page *page = vm_normal_page(vma, addr, ptent);
if (!page || !page_mapped(page))
return NULL;
if (PageAnon(page)) {
/* we don't move shared anon */
if (!move_anon())
return NULL;
} else if (!move_file())
/* we ignore mapcount for file pages */
return NULL;
if (!get_page_unless_zero(page))
return NULL;
return page;
}
#ifdef CONFIG_SWAP
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent, swp_entry_t *entry)
{
struct page *page = NULL;
swp_entry_t ent = pte_to_swp_entry(ptent);
if (!move_anon() || non_swap_entry(ent))
return NULL;
/*
* Because lookup_swap_cache() updates some statistics counter,
* we call find_get_page() with swapper_space directly.
*/
page = find_get_page(swap_address_space(ent), ent.val);
if (do_swap_account)
entry->val = ent.val;
return page;
}
#else
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent, swp_entry_t *entry)
{
return NULL;
}
#endif
static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent, swp_entry_t *entry)
{
struct page *page = NULL;
struct address_space *mapping;
pgoff_t pgoff;
if (!vma->vm_file) /* anonymous vma */
return NULL;
if (!move_file())
return NULL;
mapping = vma->vm_file->f_mapping;
if (pte_none(ptent))
pgoff = linear_page_index(vma, addr);
else /* pte_file(ptent) is true */
pgoff = pte_to_pgoff(ptent);
/* page is moved even if it's not RSS of this task(page-faulted). */
page = find_get_page(mapping, pgoff);
#ifdef CONFIG_SWAP
/* shmem/tmpfs may report page out on swap: account for that too. */
if (radix_tree_exceptional_entry(page)) {
swp_entry_t swap = radix_to_swp_entry(page);
if (do_swap_account)
*entry = swap;
page = find_get_page(swap_address_space(swap), swap.val);
}
#endif
return page;
}
static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent, union mc_target *target)
{
struct page *page = NULL;
struct page_cgroup *pc;
enum mc_target_type ret = MC_TARGET_NONE;
swp_entry_t ent = { .val = 0 };
if (pte_present(ptent))
page = mc_handle_present_pte(vma, addr, ptent);
else if (is_swap_pte(ptent))
page = mc_handle_swap_pte(vma, addr, ptent, &ent);
else if (pte_none(ptent) || pte_file(ptent))
page = mc_handle_file_pte(vma, addr, ptent, &ent);
if (!page && !ent.val)
return ret;
if (page) {
pc = lookup_page_cgroup(page);
/*
* Do only loose check w/o page_cgroup lock.
* mem_cgroup_move_account() checks the pc is valid or not under
* the lock.
*/
if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
ret = MC_TARGET_PAGE;
if (target)
target->page = page;
}
if (!ret || !target)
put_page(page);
}
/* There is a swap entry and a page doesn't exist or isn't charged */
if (ent.val && !ret &&
mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
ret = MC_TARGET_SWAP;
if (target)
target->ent = ent;
}
return ret;
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
* We don't consider swapping or file mapped pages because THP does not
* support them for now.
* Caller should make sure that pmd_trans_huge(pmd) is true.
*/
static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
unsigned long addr, pmd_t pmd, union mc_target *target)
{
struct page *page = NULL;
struct page_cgroup *pc;
enum mc_target_type ret = MC_TARGET_NONE;
page = pmd_page(pmd);
VM_BUG_ON_PAGE(!page || !PageHead(page), page);
if (!move_anon())
return ret;
pc = lookup_page_cgroup(page);
if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
ret = MC_TARGET_PAGE;
if (target) {
get_page(page);
target->page = page;
}
}
return ret;
}
#else
static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
unsigned long addr, pmd_t pmd, union mc_target *target)
{
return MC_TARGET_NONE;
}
#endif
static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->private;
pte_t *pte;
spinlock_t *ptl;
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
mc.precharge += HPAGE_PMD_NR;
spin_unlock(ptl);
return 0;
}
if (pmd_trans_unstable(pmd))
return 0;
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE)
if (get_mctgt_type(vma, addr, *pte, NULL))
mc.precharge++; /* increment precharge temporarily */
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
return 0;
}
static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
{
unsigned long precharge;
struct vm_area_struct *vma;
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
struct mm_walk mem_cgroup_count_precharge_walk = {
.pmd_entry = mem_cgroup_count_precharge_pte_range,
.mm = mm,
.private = vma,
};
if (is_vm_hugetlb_page(vma))
continue;
walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_count_precharge_walk);
}
up_read(&mm->mmap_sem);
precharge = mc.precharge;
mc.precharge = 0;
return precharge;
}
static int mem_cgroup_precharge_mc(struct mm_struct *mm)
{
unsigned long precharge = mem_cgroup_count_precharge(mm);
VM_BUG_ON(mc.moving_task);
mc.moving_task = current;
return mem_cgroup_do_precharge(precharge);
}
/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
static void __mem_cgroup_clear_mc(void)
{
struct mem_cgroup *from = mc.from;
struct mem_cgroup *to = mc.to;
int i;
/* we must uncharge all the leftover precharges from mc.to */
if (mc.precharge) {
__mem_cgroup_cancel_charge(mc.to, mc.precharge);
mc.precharge = 0;
}
/*
* we didn't uncharge from mc.from at mem_cgroup_move_account(), so
* we must uncharge here.
*/
if (mc.moved_charge) {
__mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
mc.moved_charge = 0;
}
/* we must fixup refcnts and charges */
if (mc.moved_swap) {
/* uncharge swap account from the old cgroup */
if (!mem_cgroup_is_root(mc.from))
res_counter_uncharge(&mc.from->memsw,
PAGE_SIZE * mc.moved_swap);
for (i = 0; i < mc.moved_swap; i++)
css_put(&mc.from->css);
if (!mem_cgroup_is_root(mc.to)) {
/*
* we charged both to->res and to->memsw, so we should
* uncharge to->res.
*/
res_counter_uncharge(&mc.to->res,
PAGE_SIZE * mc.moved_swap);
}
/* we've already done css_get(mc.to) */
mc.moved_swap = 0;
}
memcg_oom_recover(from);
memcg_oom_recover(to);
wake_up_all(&mc.waitq);
}
static void mem_cgroup_clear_mc(void)
{
struct mem_cgroup *from = mc.from;
/*
* we must clear moving_task before waking up waiters at the end of
* task migration.
*/
mc.moving_task = NULL;
__mem_cgroup_clear_mc();
spin_lock(&mc.lock);
mc.from = NULL;
mc.to = NULL;
spin_unlock(&mc.lock);
mem_cgroup_end_move(from);
}
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
struct task_struct *p = cgroup_taskset_first(tset);
int ret = 0;
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
unsigned long move_charge_at_immigrate;
/*
* We are now commited to this value whatever it is. Changes in this
* tunable will only affect upcoming migrations, not the current one.
* So we need to save it, and keep it going.
*/
move_charge_at_immigrate = memcg->move_charge_at_immigrate;
if (move_charge_at_immigrate) {
struct mm_struct *mm;
struct mem_cgroup *from = mem_cgroup_from_task(p);
VM_BUG_ON(from == memcg);
mm = get_task_mm(p);
if (!mm)
return 0;
/* We move charges only when we move a owner of the mm */
if (mm->owner == p) {
VM_BUG_ON(mc.from);
VM_BUG_ON(mc.to);
VM_BUG_ON(mc.precharge);
VM_BUG_ON(mc.moved_charge);
VM_BUG_ON(mc.moved_swap);
mem_cgroup_start_move(from);
spin_lock(&mc.lock);
mc.from = from;
mc.to = memcg;
mc.immigrate_flags = move_charge_at_immigrate;
spin_unlock(&mc.lock);
/* We set mc.moving_task later */
ret = mem_cgroup_precharge_mc(mm);
if (ret)
mem_cgroup_clear_mc();
}
mmput(mm);
}
return ret;
}
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
mem_cgroup_clear_mc();
}
static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
int ret = 0;
struct vm_area_struct *vma = walk->private;
pte_t *pte;
spinlock_t *ptl;
enum mc_target_type target_type;
union mc_target target;
struct page *page;
struct page_cgroup *pc;
/*
* We don't take compound_lock() here but no race with splitting thp
* happens because:
* - if pmd_trans_huge_lock() returns 1, the relevant thp is not
* under splitting, which means there's no concurrent thp split,
* - if another thread runs into split_huge_page() just after we
* entered this if-block, the thread must wait for page table lock
* to be unlocked in __split_huge_page_splitting(), where the main
* part of thp split is not executed yet.
*/
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
if (mc.precharge < HPAGE_PMD_NR) {
spin_unlock(ptl);
return 0;
}
target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
if (target_type == MC_TARGET_PAGE) {
page = target.page;
if (!isolate_lru_page(page)) {
pc = lookup_page_cgroup(page);
if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
pc, mc.from, mc.to)) {
mc.precharge -= HPAGE_PMD_NR;
mc.moved_charge += HPAGE_PMD_NR;
}
putback_lru_page(page);
}
put_page(page);
}
spin_unlock(ptl);
return 0;
}
if (pmd_trans_unstable(pmd))
return 0;
retry:
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; addr += PAGE_SIZE) {
pte_t ptent = *(pte++);
swp_entry_t ent;
if (!mc.precharge)
break;
switch (get_mctgt_type(vma, addr, ptent, &target)) {
case MC_TARGET_PAGE:
page = target.page;
if (isolate_lru_page(page))
goto put;
pc = lookup_page_cgroup(page);
if (!mem_cgroup_move_account(page, 1, pc,
mc.from, mc.to)) {
mc.precharge--;
/* we uncharge from mc.from later. */
mc.moved_charge++;
}
putback_lru_page(page);
put: /* get_mctgt_type() gets the page */
put_page(page);
break;
case MC_TARGET_SWAP:
ent = target.ent;
if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
mc.precharge--;
/* we fixup refcnts and charges later. */
mc.moved_swap++;
}
break;
default:
break;
}
}
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
if (addr != end) {
/*
* We have consumed all precharges we got in can_attach().
* We try charge one by one, but don't do any additional
* charges to mc.to if we have failed in charge once in attach()
* phase.
*/
ret = mem_cgroup_do_precharge(1);
if (!ret)
goto retry;
}
return ret;
}
static void mem_cgroup_move_charge(struct mm_struct *mm)
{
struct vm_area_struct *vma;
lru_add_drain_all();
retry:
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
/*
* Someone who are holding the mmap_sem might be waiting in
* waitq. So we cancel all extra charges, wake up all waiters,
* and retry. Because we cancel precharges, we might not be able
* to move enough charges, but moving charge is a best-effort
* feature anyway, so it wouldn't be a big problem.
*/
__mem_cgroup_clear_mc();
cond_resched();
goto retry;
}
for (vma = mm->mmap; vma; vma = vma->vm_next) {
int ret;
struct mm_walk mem_cgroup_move_charge_walk = {
.pmd_entry = mem_cgroup_move_charge_pte_range,
.mm = mm,
.private = vma,
};
if (is_vm_hugetlb_page(vma))
continue;
ret = walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_move_charge_walk);
if (ret)
/*
* means we have consumed all precharges and failed in
* doing additional charge. Just abandon here.
*/
break;
}
up_read(&mm->mmap_sem);
}
static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
struct task_struct *p = cgroup_taskset_first(tset);
struct mm_struct *mm = get_task_mm(p);
if (mm) {
if (mc.to)
mem_cgroup_move_charge(mm);
mmput(mm);
}
if (mc.to)
mem_cgroup_clear_mc();
}
#else /* !CONFIG_MMU */
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
return 0;
}
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
}
static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
}
#endif
/*
* Cgroup retains root cgroups across [un]mount cycles making it necessary
* to verify sane_behavior flag on each mount attempt.
*/
static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
{
/*
* use_hierarchy is forced with sane_behavior. cgroup core
* guarantees that @root doesn't have any children, so turning it
* on for the root memcg is enough.
*/
if (cgroup_sane_behavior(root_css->cgroup))
mem_cgroup_from_css(root_css)->use_hierarchy = true;
}
struct cgroup_subsys memory_cgrp_subsys = {
.css_alloc = mem_cgroup_css_alloc,
.css_online = mem_cgroup_css_online,
.css_offline = mem_cgroup_css_offline,
.css_free = mem_cgroup_css_free,
.can_attach = mem_cgroup_can_attach,
.cancel_attach = mem_cgroup_cancel_attach,
.attach = mem_cgroup_move_task,
.bind = mem_cgroup_bind,
.base_cftypes = mem_cgroup_files,
.early_init = 0,
};
#ifdef CONFIG_MEMCG_SWAP
static int __init enable_swap_account(char *s)
{
if (!strcmp(s, "1"))
really_do_swap_account = 1;
else if (!strcmp(s, "0"))
really_do_swap_account = 0;
return 1;
}
__setup("swapaccount=", enable_swap_account);
static void __init memsw_file_init(void)
{
WARN_ON(cgroup_add_cftypes(&memory_cgrp_subsys, memsw_cgroup_files));
}
static void __init enable_swap_cgroup(void)
{
if (!mem_cgroup_disabled() && really_do_swap_account) {
do_swap_account = 1;
memsw_file_init();
}
}
#else
static void __init enable_swap_cgroup(void)
{
}
#endif
/*
* subsys_initcall() for memory controller.
*
* Some parts like hotcpu_notifier() have to be initialized from this context
* because of lock dependencies (cgroup_lock -> cpu hotplug) but basically
* everything that doesn't depend on a specific mem_cgroup structure should
* be initialized from here.
*/
static int __init mem_cgroup_init(void)
{
hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
enable_swap_cgroup();
mem_cgroup_soft_limit_tree_init();
memcg_stock_init();
return 0;
}
subsys_initcall(mem_cgroup_init);
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