blob: 8a79a6f0f029842860fae7cd9b15c8c90600d56c [file] [log] [blame]
/* memcontrol.c - Memory Controller
*
* Copyright IBM Corporation, 2007
* Author Balbir Singh <balbir@linux.vnet.ibm.com>
*
* Copyright 2007 OpenVZ SWsoft Inc
* Author: Pavel Emelianov <xemul@openvz.org>
*
* Memory thresholds
* Copyright (C) 2009 Nokia Corporation
* Author: Kirill A. Shutemov
*
* 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/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/sort.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <linux/mm_inline.h>
#include <linux/page_cgroup.h>
#include <linux/cpu.h>
#include "internal.h"
#include <asm/uaccess.h>
struct cgroup_subsys mem_cgroup_subsys __read_mostly;
#define MEM_CGROUP_RECLAIM_RETRIES 5
struct mem_cgroup *root_mem_cgroup __read_mostly;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
int do_swap_account __read_mostly;
static int really_do_swap_account __initdata = 1; /* for remember boot option*/
#else
#define do_swap_account (0)
#endif
/*
* Per memcg event counter is incremented at every pagein/pageout. This counter
* is used for trigger some periodic events. This is straightforward and better
* than using jiffies etc. to handle periodic memcg event.
*
* These values will be used as !((event) & ((1 <<(thresh)) - 1))
*/
#define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
#define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
/*
* Statistics for memory cgroup.
*/
enum mem_cgroup_stat_index {
/*
* For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
*/
MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */
MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */
MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */
MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */
MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */
MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
MEM_CGROUP_EVENTS, /* incremented at every pagein/pageout */
MEM_CGROUP_STAT_NSTATS,
};
struct mem_cgroup_stat_cpu {
s64 count[MEM_CGROUP_STAT_NSTATS];
};
/*
* per-zone information in memory controller.
*/
struct mem_cgroup_per_zone {
/*
* spin_lock to protect the per cgroup LRU
*/
struct list_head lists[NR_LRU_LISTS];
unsigned long count[NR_LRU_LISTS];
struct zone_reclaim_stat reclaim_stat;
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 *mem; /* Back pointer, we cannot */
/* use container_of */
};
/* Macro for accessing counter */
#define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)])
struct mem_cgroup_per_node {
struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
};
struct mem_cgroup_lru_info {
struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
};
/*
* 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;
};
struct mem_cgroup_threshold_ary {
/* An array index points to threshold just below usage. */
atomic_t current_threshold;
/* Size of entries[] */
unsigned int size;
/* Array of thresholds */
struct mem_cgroup_threshold entries[0];
};
static void mem_cgroup_threshold(struct mem_cgroup *mem);
/*
* 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;
/*
* the counter to account for mem+swap usage.
*/
struct res_counter memsw;
/*
* Per cgroup active and inactive list, similar to the
* per zone LRU lists.
*/
struct mem_cgroup_lru_info info;
/*
protect against reclaim related member.
*/
spinlock_t reclaim_param_lock;
int prev_priority; /* for recording reclaim priority */
/*
* While reclaiming in a hierarchy, we cache the last child we
* reclaimed from.
*/
int last_scanned_child;
/*
* Should the accounting and control be hierarchical, per subtree?
*/
bool use_hierarchy;
atomic_t oom_lock;
atomic_t refcnt;
unsigned int swappiness;
/* 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_threshold_ary *thresholds;
/* thresholds for mem+swap usage. RCU-protected */
struct mem_cgroup_threshold_ary *memsw_thresholds;
/*
* 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;
/*
* percpu counter.
*/
struct mem_cgroup_stat_cpu *stat;
};
/* Stuffs for move charges at task migration. */
/*
* Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
* left-shifted bitmap of these types.
*/
enum move_type {
MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
NR_MOVE_TYPE,
};
/* "mc" and its members are protected by cgroup_mutex */
static struct move_charge_struct {
struct mem_cgroup *from;
struct mem_cgroup *to;
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 = {
.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};
/*
* Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
* limit reclaim to prevent infinite loops, if they ever occur.
*/
#define MEM_CGROUP_MAX_RECLAIM_LOOPS (100)
#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2)
enum charge_type {
MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
MEM_CGROUP_CHARGE_TYPE_MAPPED,
MEM_CGROUP_CHARGE_TYPE_SHMEM, /* used by page migration of shmem */
MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */
MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */
NR_CHARGE_TYPE,
};
/* only for here (for easy reading.) */
#define PCGF_CACHE (1UL << PCG_CACHE)
#define PCGF_USED (1UL << PCG_USED)
#define PCGF_LOCK (1UL << PCG_LOCK)
/* Not used, but added here for completeness */
#define PCGF_ACCT (1UL << PCG_ACCT)
/* for encoding cft->private value on file */
#define _MEM (0)
#define _MEMSWAP (1)
#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
#define MEMFILE_TYPE(val) (((val) >> 16) & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
/*
* 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)
#define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2
#define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
static void mem_cgroup_get(struct mem_cgroup *mem);
static void mem_cgroup_put(struct mem_cgroup *mem);
static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
static void drain_all_stock_async(void);
static struct mem_cgroup_per_zone *
mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
{
return &mem->info.nodeinfo[nid]->zoneinfo[zid];
}
struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
{
return &mem->css;
}
static struct mem_cgroup_per_zone *
page_cgroup_zoneinfo(struct page_cgroup *pc)
{
struct mem_cgroup *mem = pc->mem_cgroup;
int nid = page_cgroup_nid(pc);
int zid = page_cgroup_zid(pc);
if (!mem)
return NULL;
return mem_cgroup_zoneinfo(mem, 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 *mem,
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 *mem,
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 *mem,
struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz)
{
spin_lock(&mctz->lock);
__mem_cgroup_remove_exceeded(mem, mz, mctz);
spin_unlock(&mctz->lock);
}
static void mem_cgroup_update_tree(struct mem_cgroup *mem, 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 (; mem; mem = parent_mem_cgroup(mem)) {
mz = mem_cgroup_zoneinfo(mem, nid, zid);
excess = res_counter_soft_limit_excess(&mem->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(mem, mz, mctz);
/*
* Insert again. mz->usage_in_excess will be updated.
* If excess is 0, no tree ops.
*/
__mem_cgroup_insert_exceeded(mem, mz, mctz, excess);
spin_unlock(&mctz->lock);
}
}
}
static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
{
int node, zone;
struct mem_cgroup_per_zone *mz;
struct mem_cgroup_tree_per_zone *mctz;
for_each_node_state(node, N_POSSIBLE) {
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
mz = mem_cgroup_zoneinfo(mem, node, zone);
mctz = soft_limit_tree_node_zone(node, zone);
mem_cgroup_remove_exceeded(mem, mz, mctz);
}
}
}
static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
{
return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
}
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->mem, mz, mctz);
if (!res_counter_soft_limit_excess(&mz->mem->res) ||
!css_tryget(&mz->mem->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;
}
static s64 mem_cgroup_read_stat(struct mem_cgroup *mem,
enum mem_cgroup_stat_index idx)
{
int cpu;
s64 val = 0;
for_each_possible_cpu(cpu)
val += per_cpu(mem->stat->count[idx], cpu);
return val;
}
static s64 mem_cgroup_local_usage(struct mem_cgroup *mem)
{
s64 ret;
ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
return ret;
}
static void mem_cgroup_swap_statistics(struct mem_cgroup *mem,
bool charge)
{
int val = (charge) ? 1 : -1;
this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
}
static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
struct page_cgroup *pc,
bool charge)
{
int val = (charge) ? 1 : -1;
preempt_disable();
if (PageCgroupCache(pc))
__this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_CACHE], val);
else
__this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_RSS], val);
if (charge)
__this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
else
__this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
__this_cpu_inc(mem->stat->count[MEM_CGROUP_EVENTS]);
preempt_enable();
}
static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
enum lru_list idx)
{
int nid, zid;
struct mem_cgroup_per_zone *mz;
u64 total = 0;
for_each_online_node(nid)
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
mz = mem_cgroup_zoneinfo(mem, nid, zid);
total += MEM_CGROUP_ZSTAT(mz, idx);
}
return total;
}
static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
{
s64 val;
val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
return !(val & ((1 << event_mask_shift) - 1));
}
/*
* Check events in order.
*
*/
static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
{
/* threshold event is triggered in finer grain than soft limit */
if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
mem_cgroup_threshold(mem);
if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
mem_cgroup_update_tree(mem, page);
}
}
static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
{
return container_of(cgroup_subsys_state(cont,
mem_cgroup_subsys_id), struct mem_cgroup,
css);
}
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 container_of(task_subsys_state(p, mem_cgroup_subsys_id),
struct mem_cgroup, css);
}
static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
{
struct mem_cgroup *mem = NULL;
if (!mm)
return NULL;
/*
* Because we have no locks, mm->owner's may be being moved to other
* cgroup. We use css_tryget() here even if this looks
* pessimistic (rather than adding locks here).
*/
rcu_read_lock();
do {
mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!mem))
break;
} while (!css_tryget(&mem->css));
rcu_read_unlock();
return mem;
}
/*
* Call callback function against all cgroup under hierarchy tree.
*/
static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
int (*func)(struct mem_cgroup *, void *))
{
int found, ret, nextid;
struct cgroup_subsys_state *css;
struct mem_cgroup *mem;
if (!root->use_hierarchy)
return (*func)(root, data);
nextid = 1;
do {
ret = 0;
mem = NULL;
rcu_read_lock();
css = css_get_next(&mem_cgroup_subsys, nextid, &root->css,
&found);
if (css && css_tryget(css))
mem = container_of(css, struct mem_cgroup, css);
rcu_read_unlock();
if (mem) {
ret = (*func)(mem, data);
css_put(&mem->css);
}
nextid = found + 1;
} while (!ret && css);
return ret;
}
static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
{
return (mem == root_mem_cgroup);
}
/*
* 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.
*/
void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
{
struct page_cgroup *pc;
struct mem_cgroup_per_zone *mz;
if (mem_cgroup_disabled())
return;
pc = lookup_page_cgroup(page);
/* can happen while we handle swapcache. */
if (!TestClearPageCgroupAcctLRU(pc))
return;
VM_BUG_ON(!pc->mem_cgroup);
/*
* We don't check PCG_USED bit. It's cleared when the "page" is finally
* removed from global LRU.
*/
mz = page_cgroup_zoneinfo(pc);
MEM_CGROUP_ZSTAT(mz, lru) -= 1;
if (mem_cgroup_is_root(pc->mem_cgroup))
return;
VM_BUG_ON(list_empty(&pc->lru));
list_del_init(&pc->lru);
return;
}
void mem_cgroup_del_lru(struct page *page)
{
mem_cgroup_del_lru_list(page, page_lru(page));
}
void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
{
struct mem_cgroup_per_zone *mz;
struct page_cgroup *pc;
if (mem_cgroup_disabled())
return;
pc = lookup_page_cgroup(page);
/*
* Used bit is set without atomic ops but after smp_wmb().
* For making pc->mem_cgroup visible, insert smp_rmb() here.
*/
smp_rmb();
/* unused or root page is not rotated. */
if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
return;
mz = page_cgroup_zoneinfo(pc);
list_move(&pc->lru, &mz->lists[lru]);
}
void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
{
struct page_cgroup *pc;
struct mem_cgroup_per_zone *mz;
if (mem_cgroup_disabled())
return;
pc = lookup_page_cgroup(page);
VM_BUG_ON(PageCgroupAcctLRU(pc));
/*
* Used bit is set without atomic ops but after smp_wmb().
* For making pc->mem_cgroup visible, insert smp_rmb() here.
*/
smp_rmb();
if (!PageCgroupUsed(pc))
return;
mz = page_cgroup_zoneinfo(pc);
MEM_CGROUP_ZSTAT(mz, lru) += 1;
SetPageCgroupAcctLRU(pc);
if (mem_cgroup_is_root(pc->mem_cgroup))
return;
list_add(&pc->lru, &mz->lists[lru]);
}
/*
* At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
* lru because the page may.be reused after it's fully uncharged (because of
* SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
* it again. This function is only used to charge SwapCache. It's done under
* lock_page and expected that zone->lru_lock is never held.
*/
static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
{
unsigned long flags;
struct zone *zone = page_zone(page);
struct page_cgroup *pc = lookup_page_cgroup(page);
spin_lock_irqsave(&zone->lru_lock, flags);
/*
* Forget old LRU when this page_cgroup is *not* used. This Used bit
* is guarded by lock_page() because the page is SwapCache.
*/
if (!PageCgroupUsed(pc))
mem_cgroup_del_lru_list(page, page_lru(page));
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
{
unsigned long flags;
struct zone *zone = page_zone(page);
struct page_cgroup *pc = lookup_page_cgroup(page);
spin_lock_irqsave(&zone->lru_lock, flags);
/* link when the page is linked to LRU but page_cgroup isn't */
if (PageLRU(page) && !PageCgroupAcctLRU(pc))
mem_cgroup_add_lru_list(page, page_lru(page));
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
void mem_cgroup_move_lists(struct page *page,
enum lru_list from, enum lru_list to)
{
if (mem_cgroup_disabled())
return;
mem_cgroup_del_lru_list(page, from);
mem_cgroup_add_lru_list(page, to);
}
int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
{
int ret;
struct mem_cgroup *curr = NULL;
task_lock(task);
rcu_read_lock();
curr = try_get_mem_cgroup_from_mm(task->mm);
rcu_read_unlock();
task_unlock(task);
if (!curr)
return 0;
/*
* We should check use_hierarchy of "mem" 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 "mem" in *cgroup*
* hierarchy(even if use_hierarchy is disabled in "mem").
*/
if (mem->use_hierarchy)
ret = css_is_ancestor(&curr->css, &mem->css);
else
ret = (curr == mem);
css_put(&curr->css);
return ret;
}
/*
* prev_priority control...this will be used in memory reclaim path.
*/
int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
{
int prev_priority;
spin_lock(&mem->reclaim_param_lock);
prev_priority = mem->prev_priority;
spin_unlock(&mem->reclaim_param_lock);
return prev_priority;
}
void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority)
{
spin_lock(&mem->reclaim_param_lock);
if (priority < mem->prev_priority)
mem->prev_priority = priority;
spin_unlock(&mem->reclaim_param_lock);
}
void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
{
spin_lock(&mem->reclaim_param_lock);
mem->prev_priority = priority;
spin_unlock(&mem->reclaim_param_lock);
}
static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
{
unsigned long active;
unsigned long inactive;
unsigned long gb;
unsigned long inactive_ratio;
inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_ANON);
active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_ANON);
gb = (inactive + active) >> (30 - PAGE_SHIFT);
if (gb)
inactive_ratio = int_sqrt(10 * gb);
else
inactive_ratio = 1;
if (present_pages) {
present_pages[0] = inactive;
present_pages[1] = active;
}
return inactive_ratio;
}
int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
{
unsigned long active;
unsigned long inactive;
unsigned long present_pages[2];
unsigned long inactive_ratio;
inactive_ratio = calc_inactive_ratio(memcg, present_pages);
inactive = present_pages[0];
active = present_pages[1];
if (inactive * inactive_ratio < active)
return 1;
return 0;
}
int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
{
unsigned long active;
unsigned long inactive;
inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE);
active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE);
return (active > inactive);
}
unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
struct zone *zone,
enum lru_list lru)
{
int nid = zone->zone_pgdat->node_id;
int zid = zone_idx(zone);
struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
return MEM_CGROUP_ZSTAT(mz, lru);
}
struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
struct zone *zone)
{
int nid = zone->zone_pgdat->node_id;
int zid = zone_idx(zone);
struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
return &mz->reclaim_stat;
}
struct zone_reclaim_stat *
mem_cgroup_get_reclaim_stat_from_page(struct page *page)
{
struct page_cgroup *pc;
struct mem_cgroup_per_zone *mz;
if (mem_cgroup_disabled())
return NULL;
pc = lookup_page_cgroup(page);
/*
* Used bit is set without atomic ops but after smp_wmb().
* For making pc->mem_cgroup visible, insert smp_rmb() here.
*/
smp_rmb();
if (!PageCgroupUsed(pc))
return NULL;
mz = page_cgroup_zoneinfo(pc);
if (!mz)
return NULL;
return &mz->reclaim_stat;
}
unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
struct list_head *dst,
unsigned long *scanned, int order,
int mode, struct zone *z,
struct mem_cgroup *mem_cont,
int active, int file)
{
unsigned long nr_taken = 0;
struct page *page;
unsigned long scan;
LIST_HEAD(pc_list);
struct list_head *src;
struct page_cgroup *pc, *tmp;
int nid = z->zone_pgdat->node_id;
int zid = zone_idx(z);
struct mem_cgroup_per_zone *mz;
int lru = LRU_FILE * file + active;
int ret;
BUG_ON(!mem_cont);
mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
src = &mz->lists[lru];
scan = 0;
list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
if (scan >= nr_to_scan)
break;
page = pc->page;
if (unlikely(!PageCgroupUsed(pc)))
continue;
if (unlikely(!PageLRU(page)))
continue;
scan++;
ret = __isolate_lru_page(page, mode, file);
switch (ret) {
case 0:
list_move(&page->lru, dst);
mem_cgroup_del_lru(page);
nr_taken++;
break;
case -EBUSY:
/* we don't affect global LRU but rotate in our LRU */
mem_cgroup_rotate_lru_list(page, page_lru(page));
break;
default:
break;
}
}
*scanned = scan;
return nr_taken;
}
#define mem_cgroup_from_res_counter(counter, member) \
container_of(counter, struct mem_cgroup, member)
static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
{
if (do_swap_account) {
if (res_counter_check_under_limit(&mem->res) &&
res_counter_check_under_limit(&mem->memsw))
return true;
} else
if (res_counter_check_under_limit(&mem->res))
return true;
return false;
}
static unsigned int get_swappiness(struct mem_cgroup *memcg)
{
struct cgroup *cgrp = memcg->css.cgroup;
unsigned int swappiness;
/* root ? */
if (cgrp->parent == NULL)
return vm_swappiness;
spin_lock(&memcg->reclaim_param_lock);
swappiness = memcg->swappiness;
spin_unlock(&memcg->reclaim_param_lock);
return swappiness;
}
static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
{
int *val = data;
(*val)++;
return 0;
}
/**
* mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
* @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)
{
struct cgroup *task_cgrp;
struct cgroup *mem_cgrp;
/*
* Need a buffer in BSS, can't rely on allocations. The code relies
* on the assumption that OOM is serialized for memory controller.
* If this assumption is broken, revisit this code.
*/
static char memcg_name[PATH_MAX];
int ret;
if (!memcg || !p)
return;
rcu_read_lock();
mem_cgrp = memcg->css.cgroup;
task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
if (ret < 0) {
/*
* Unfortunately, we are unable to convert to a useful name
* But we'll still print out the usage information
*/
rcu_read_unlock();
goto done;
}
rcu_read_unlock();
printk(KERN_INFO "Task in %s killed", memcg_name);
rcu_read_lock();
ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
if (ret < 0) {
rcu_read_unlock();
goto done;
}
rcu_read_unlock();
/*
* Continues from above, so we don't need an KERN_ level
*/
printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
done:
printk(KERN_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));
printk(KERN_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));
}
/*
* 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 *mem)
{
int num = 0;
mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb);
return num;
}
/*
* Visit the first child (need not be the first child as per the ordering
* of the cgroup list, since we track last_scanned_child) of @mem and use
* that to reclaim free pages from.
*/
static struct mem_cgroup *
mem_cgroup_select_victim(struct mem_cgroup *root_mem)
{
struct mem_cgroup *ret = NULL;
struct cgroup_subsys_state *css;
int nextid, found;
if (!root_mem->use_hierarchy) {
css_get(&root_mem->css);
ret = root_mem;
}
while (!ret) {
rcu_read_lock();
nextid = root_mem->last_scanned_child + 1;
css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css,
&found);
if (css && css_tryget(css))
ret = container_of(css, struct mem_cgroup, css);
rcu_read_unlock();
/* Updates scanning parameter */
spin_lock(&root_mem->reclaim_param_lock);
if (!css) {
/* this means start scan from ID:1 */
root_mem->last_scanned_child = 0;
} else
root_mem->last_scanned_child = found;
spin_unlock(&root_mem->reclaim_param_lock);
}
return ret;
}
/*
* Scan the hierarchy if needed to reclaim memory. We remember the last child
* we reclaimed from, so that we don't end up penalizing one child extensively
* based on its position in the children list.
*
* root_mem is the original ancestor that we've been reclaim from.
*
* We give up and return to the caller when we visit root_mem twice.
* (other groups can be removed while we're walking....)
*
* If shrink==true, for avoiding to free too much, this returns immedieately.
*/
static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
struct zone *zone,
gfp_t gfp_mask,
unsigned long reclaim_options)
{
struct mem_cgroup *victim;
int ret, total = 0;
int loop = 0;
bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
unsigned long excess = mem_cgroup_get_excess(root_mem);
/* If memsw_is_minimum==1, swap-out is of-no-use. */
if (root_mem->memsw_is_minimum)
noswap = true;
while (1) {
victim = mem_cgroup_select_victim(root_mem);
if (victim == root_mem) {
loop++;
if (loop >= 1)
drain_all_stock_async();
if (loop >= 2) {
/*
* If we have not been able to reclaim
* anything, it might because there are
* no reclaimable pages under this hierarchy
*/
if (!check_soft || !total) {
css_put(&victim->css);
break;
}
/*
* We want to do more targetted 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)) {
css_put(&victim->css);
break;
}
}
}
if (!mem_cgroup_local_usage(victim)) {
/* this cgroup's local usage == 0 */
css_put(&victim->css);
continue;
}
/* we use swappiness of local cgroup */
if (check_soft)
ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
noswap, get_swappiness(victim), zone,
zone->zone_pgdat->node_id);
else
ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
noswap, get_swappiness(victim));
css_put(&victim->css);
/*
* At shrinking usage, we can't check we should stop here or
* reclaim more. It's depends on callers. last_scanned_child
* will work enough for keeping fairness under tree.
*/
if (shrink)
return ret;
total += ret;
if (check_soft) {
if (res_counter_check_under_soft_limit(&root_mem->res))
return total;
} else if (mem_cgroup_check_under_limit(root_mem))
return 1 + total;
}
return total;
}
static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data)
{
int *val = (int *)data;
int x;
/*
* Logically, we can stop scanning immediately when we find
* a memcg is already locked. But condidering unlock ops and
* creation/removal of memcg, scan-all is simple operation.
*/
x = atomic_inc_return(&mem->oom_lock);
*val = max(x, *val);
return 0;
}
/*
* Check OOM-Killer is already running under our hierarchy.
* If someone is running, return false.
*/
static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
{
int lock_count = 0;
mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb);
if (lock_count == 1)
return true;
return false;
}
static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data)
{
/*
* 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.
*/
atomic_add_unless(&mem->oom_lock, -1, 0);
return 0;
}
static void mem_cgroup_oom_unlock(struct mem_cgroup *mem)
{
mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb);
}
static DEFINE_MUTEX(memcg_oom_mutex);
static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
/*
* try to call OOM killer. returns false if we should exit memory-reclaim loop.
*/
bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
{
DEFINE_WAIT(wait);
bool locked;
/* At first, try to OOM lock hierarchy under mem.*/
mutex_lock(&memcg_oom_mutex);
locked = mem_cgroup_oom_lock(mem);
/*
* Even if signal_pending(), we can't quit charge() loop without
* accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
* under OOM is always welcomed, use TASK_KILLABLE here.
*/
if (!locked)
prepare_to_wait(&memcg_oom_waitq, &wait, TASK_KILLABLE);
mutex_unlock(&memcg_oom_mutex);
if (locked)
mem_cgroup_out_of_memory(mem, mask);
else {
schedule();
finish_wait(&memcg_oom_waitq, &wait);
}
mutex_lock(&memcg_oom_mutex);
mem_cgroup_oom_unlock(mem);
/*
* Here, we use global waitq .....more fine grained waitq ?
* Assume following hierarchy.
* A/
* 01
* 02
* assume OOM happens both in A and 01 at the same time. Tthey are
* mutually exclusive by lock. (kill in 01 helps A.)
* When we use per memcg waitq, we have to wake up waiters on A and 02
* in addtion to waiters on 01. We use global waitq for avoiding mess.
* It will not be a big problem.
* (And a task may be moved to other groups while it's waiting for OOM.)
*/
wake_up_all(&memcg_oom_waitq);
mutex_unlock(&memcg_oom_mutex);
if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
return false;
/* Give chance to dying process */
schedule_timeout(1);
return true;
}
/*
* Currently used to update mapped file statistics, but the routine can be
* generalized to update other statistics as well.
*/
void mem_cgroup_update_file_mapped(struct page *page, int val)
{
struct mem_cgroup *mem;
struct page_cgroup *pc;
pc = lookup_page_cgroup(page);
if (unlikely(!pc))
return;
lock_page_cgroup(pc);
mem = pc->mem_cgroup;
if (!mem || !PageCgroupUsed(pc))
goto done;
/*
* Preemption is already disabled. We can use __this_cpu_xxx
*/
if (val > 0) {
__this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
SetPageCgroupFileMapped(pc);
} else {
__this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
ClearPageCgroupFileMapped(pc);
}
done:
unlock_page_cgroup(pc);
}
/*
* 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_SIZE (32 * PAGE_SIZE)
struct memcg_stock_pcp {
struct mem_cgroup *cached; /* this never be root cgroup */
int charge;
struct work_struct work;
};
static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
static atomic_t memcg_drain_count;
/*
* Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed
* from local stock and true is returned. If the stock is 0 or charges from a
* cgroup which is not current target, returns false. This stock will be
* refilled.
*/
static bool consume_stock(struct mem_cgroup *mem)
{
struct memcg_stock_pcp *stock;
bool ret = true;
stock = &get_cpu_var(memcg_stock);
if (mem == stock->cached && stock->charge)
stock->charge -= PAGE_SIZE;
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->charge) {
res_counter_uncharge(&old->res, stock->charge);
if (do_swap_account)
res_counter_uncharge(&old->memsw, stock->charge);
}
stock->cached = NULL;
stock->charge = 0;
}
/*
* 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);
}
/*
* Cache charges(val) which is from res_counter, to local per_cpu area.
* This will be consumed by consumt_stock() function, later.
*/
static void refill_stock(struct mem_cgroup *mem, int val)
{
struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
if (stock->cached != mem) { /* reset if necessary */
drain_stock(stock);
stock->cached = mem;
}
stock->charge += val;
put_cpu_var(memcg_stock);
}
/*
* 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(void)
{
int cpu;
/* This function is for scheduling "drain" in asynchronous way.
* The result of "drain" is not directly handled by callers. Then,
* if someone is calling drain, we don't have to call drain more.
* Anyway, WORK_STRUCT_PENDING check in queue_work_on() will catch if
* there is a race. We just do loose check here.
*/
if (atomic_read(&memcg_drain_count))
return;
/* Notify other cpus that system-wide "drain" is running */
atomic_inc(&memcg_drain_count);
get_online_cpus();
for_each_online_cpu(cpu) {
struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
schedule_work_on(cpu, &stock->work);
}
put_online_cpus();
atomic_dec(&memcg_drain_count);
/* We don't wait for flush_work */
}
/* This is a synchronous drain interface. */
static void drain_all_stock_sync(void)
{
/* called when force_empty is called */
atomic_inc(&memcg_drain_count);
schedule_on_each_cpu(drain_local_stock);
atomic_dec(&memcg_drain_count);
}
static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb,
unsigned long action,
void *hcpu)
{
int cpu = (unsigned long)hcpu;
struct memcg_stock_pcp *stock;
if (action != CPU_DEAD)
return NOTIFY_OK;
stock = &per_cpu(memcg_stock, cpu);
drain_stock(stock);
return NOTIFY_OK;
}
/*
* Unlike exported interface, "oom" parameter is added. if oom==true,
* oom-killer can be invoked.
*/
static int __mem_cgroup_try_charge(struct mm_struct *mm,
gfp_t gfp_mask, struct mem_cgroup **memcg, bool oom)
{
struct mem_cgroup *mem, *mem_over_limit;
int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
struct res_counter *fail_res;
int csize = CHARGE_SIZE;
/*
* Unlike gloval-vm's OOM-kill, we're not in memory shortage
* in system level. So, allow to go ahead dying process in addition to
* MEMDIE process.
*/
if (unlikely(test_thread_flag(TIF_MEMDIE)
|| fatal_signal_pending(current)))
goto bypass;
/*
* We always charge the cgroup the mm_struct belongs to.
* The mm_struct's mem_cgroup changes on task migration if the
* thread group leader migrates. It's possible that mm is not
* set, if so charge the init_mm (happens for pagecache usage).
*/
mem = *memcg;
if (likely(!mem)) {
mem = try_get_mem_cgroup_from_mm(mm);
*memcg = mem;
} else {
css_get(&mem->css);
}
if (unlikely(!mem))
return 0;
VM_BUG_ON(css_is_removed(&mem->css));
if (mem_cgroup_is_root(mem))
goto done;
while (1) {
int ret = 0;
unsigned long flags = 0;
if (consume_stock(mem))
goto done;
ret = res_counter_charge(&mem->res, csize, &fail_res);
if (likely(!ret)) {
if (!do_swap_account)
break;
ret = res_counter_charge(&mem->memsw, csize, &fail_res);
if (likely(!ret))
break;
/* mem+swap counter fails */
res_counter_uncharge(&mem->res, csize);
flags |= MEM_CGROUP_RECLAIM_NOSWAP;
mem_over_limit = mem_cgroup_from_res_counter(fail_res,
memsw);
} else
/* mem counter fails */
mem_over_limit = mem_cgroup_from_res_counter(fail_res,
res);
/* reduce request size and retry */
if (csize > PAGE_SIZE) {
csize = PAGE_SIZE;
continue;
}
if (!(gfp_mask & __GFP_WAIT))
goto nomem;
ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
gfp_mask, flags);
if (ret)
continue;
/*
* try_to_free_mem_cgroup_pages() might not give us a full
* picture of reclaim. Some pages are reclaimed and might be
* moved to swap cache or just unmapped from the cgroup.
* Check the limit again to see if the reclaim reduced the
* current usage of the cgroup before giving up
*
*/
if (mem_cgroup_check_under_limit(mem_over_limit))
continue;
/* try to avoid oom while someone is moving charge */
if (mc.moving_task && current != mc.moving_task) {
struct mem_cgroup *from, *to;
bool do_continue = false;
/*
* There is a small race that "from" or "to" can be
* freed by rmdir, so we use css_tryget().
*/
from = mc.from;
to = mc.to;
if (from && css_tryget(&from->css)) {
if (mem_over_limit->use_hierarchy)
do_continue = css_is_ancestor(
&from->css,
&mem_over_limit->css);
else
do_continue = (from == mem_over_limit);
css_put(&from->css);
}
if (!do_continue && to && css_tryget(&to->css)) {
if (mem_over_limit->use_hierarchy)
do_continue = css_is_ancestor(
&to->css,
&mem_over_limit->css);
else
do_continue = (to == mem_over_limit);
css_put(&to->css);
}
if (do_continue) {
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);
continue;
}
}
if (!nr_retries--) {
if (!oom)
goto nomem;
if (mem_cgroup_handle_oom(mem_over_limit, gfp_mask)) {
nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
continue;
}
/* When we reach here, current task is dying .*/
css_put(&mem->css);
goto bypass;
}
}
if (csize > PAGE_SIZE)
refill_stock(mem, csize - PAGE_SIZE);
done:
return 0;
nomem:
css_put(&mem->css);
return -ENOMEM;
bypass:
*memcg = NULL;
return 0;
}
/*
* 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 *mem,
unsigned long count)
{
if (!mem_cgroup_is_root(mem)) {
res_counter_uncharge(&mem->res, PAGE_SIZE * count);
if (do_swap_account)
res_counter_uncharge(&mem->memsw, PAGE_SIZE * count);
VM_BUG_ON(test_bit(CSS_ROOT, &mem->css.flags));
WARN_ON_ONCE(count > INT_MAX);
__css_put(&mem->css, (int)count);
}
/* we don't need css_put for root */
}
static void mem_cgroup_cancel_charge(struct mem_cgroup *mem)
{
__mem_cgroup_cancel_charge(mem, 1);
}
/*
* A helper function to get mem_cgroup from ID. must be called under
* rcu_read_lock(). The caller must check css_is_removed() or some if
* it's concern. (dropping refcnt from swap can be called against removed
* memcg.)
*/
static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
{
struct cgroup_subsys_state *css;
/* ID 0 is unused ID */
if (!id)
return NULL;
css = css_lookup(&mem_cgroup_subsys, id);
if (!css)
return NULL;
return container_of(css, struct mem_cgroup, css);
}
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
{
struct mem_cgroup *mem = NULL;
struct page_cgroup *pc;
unsigned short id;
swp_entry_t ent;
VM_BUG_ON(!PageLocked(page));
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
mem = pc->mem_cgroup;
if (mem && !css_tryget(&mem->css))
mem = NULL;
} else if (PageSwapCache(page)) {
ent.val = page_private(page);
id = lookup_swap_cgroup(ent);
rcu_read_lock();
mem = mem_cgroup_lookup(id);
if (mem && !css_tryget(&mem->css))
mem = NULL;
rcu_read_unlock();
}
unlock_page_cgroup(pc);
return mem;
}
/*
* commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
* USED state. If already USED, uncharge and return.
*/
static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
struct page_cgroup *pc,
enum charge_type ctype)
{
/* try_charge() can return NULL to *memcg, taking care of it. */
if (!mem)
return;
lock_page_cgroup(pc);
if (unlikely(PageCgroupUsed(pc))) {
unlock_page_cgroup(pc);
mem_cgroup_cancel_charge(mem);
return;
}
pc->mem_cgroup = mem;
/*
* 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();
switch (ctype) {
case MEM_CGROUP_CHARGE_TYPE_CACHE:
case MEM_CGROUP_CHARGE_TYPE_SHMEM:
SetPageCgroupCache(pc);
SetPageCgroupUsed(pc);
break;
case MEM_CGROUP_CHARGE_TYPE_MAPPED:
ClearPageCgroupCache(pc);
SetPageCgroupUsed(pc);
break;
default:
break;
}
mem_cgroup_charge_statistics(mem, pc, true);
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(mem, pc->page);
}
/**
* __mem_cgroup_move_account - move account of the page
* @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.
* @uncharge: whether we should call uncharge and css_put against @from.
*
* The caller must confirm following.
* - page is not on LRU (isolate_page() is useful.)
* - the pc is locked, used, and ->mem_cgroup points to @from.
*
* This function doesn't do "charge" nor css_get to new cgroup. It should be
* done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
* true, this function does "uncharge" from old cgroup, but it doesn't if
* @uncharge is false, so a caller should do "uncharge".
*/
static void __mem_cgroup_move_account(struct page_cgroup *pc,
struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
{
VM_BUG_ON(from == to);
VM_BUG_ON(PageLRU(pc->page));
VM_BUG_ON(!PageCgroupLocked(pc));
VM_BUG_ON(!PageCgroupUsed(pc));
VM_BUG_ON(pc->mem_cgroup != from);
if (PageCgroupFileMapped(pc)) {
/* Update mapped_file data for mem_cgroup */
preempt_disable();
__this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
__this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
preempt_enable();
}
mem_cgroup_charge_statistics(from, pc, false);
if (uncharge)
/* This is not "cancel", but cancel_charge does all we need. */
mem_cgroup_cancel_charge(from);
/* caller should have done css_get */
pc->mem_cgroup = to;
mem_cgroup_charge_statistics(to, pc, true);
/*
* We charges against "to" which may not have any tasks. Then, "to"
* can be under rmdir(). But in current implementation, caller of
* this function is just force_empty() and move charge, so it's
* garanteed that "to" is never removed. So, we don't check rmdir
* status here.
*/
}
/*
* check whether the @pc is valid for moving account and call
* __mem_cgroup_move_account()
*/
static int mem_cgroup_move_account(struct page_cgroup *pc,
struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
{
int ret = -EINVAL;
lock_page_cgroup(pc);
if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
__mem_cgroup_move_account(pc, from, to, uncharge);
ret = 0;
}
unlock_page_cgroup(pc);
/*
* check events
*/
memcg_check_events(to, pc->page);
memcg_check_events(from, pc->page);
return ret;
}
/*
* move charges to its parent.
*/
static int mem_cgroup_move_parent(struct page_cgroup *pc,
struct mem_cgroup *child,
gfp_t gfp_mask)
{
struct page *page = pc->page;
struct cgroup *cg = child->css.cgroup;
struct cgroup *pcg = cg->parent;
struct mem_cgroup *parent;
int ret;
/* Is ROOT ? */
if (!pcg)
return -EINVAL;
ret = -EBUSY;
if (!get_page_unless_zero(page))
goto out;
if (isolate_lru_page(page))
goto put;
parent = mem_cgroup_from_cont(pcg);
ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
if (ret || !parent)
goto put_back;
ret = mem_cgroup_move_account(pc, child, parent, true);
if (ret)
mem_cgroup_cancel_charge(parent);
put_back:
putback_lru_page(page);
put:
put_page(page);
out:
return ret;
}
/*
* Charge the memory controller for page usage.
* Return
* 0 if the charge was successful
* < 0 if the cgroup is over its limit
*/
static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask, enum charge_type ctype,
struct mem_cgroup *memcg)
{
struct mem_cgroup *mem;
struct page_cgroup *pc;
int ret;
pc = lookup_page_cgroup(page);
/* can happen at boot */
if (unlikely(!pc))
return 0;
prefetchw(pc);
mem = memcg;
ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
if (ret || !mem)
return ret;
__mem_cgroup_commit_charge(mem, pc, ctype);
return 0;
}
int mem_cgroup_newpage_charge(struct page *page,
struct mm_struct *mm, gfp_t gfp_mask)
{
if (mem_cgroup_disabled())
return 0;
if (PageCompound(page))
return 0;
/*
* If already mapped, we don't have to account.
* If page cache, page->mapping has address_space.
* But page->mapping may have out-of-use anon_vma pointer,
* detecit it by PageAnon() check. newly-mapped-anon's page->mapping
* is NULL.
*/
if (page_mapped(page) || (page->mapping && !PageAnon(page)))
return 0;
if (unlikely(!mm))
mm = &init_mm;
return mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
}
static void
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
enum charge_type ctype);
int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
struct mem_cgroup *mem = NULL;
int ret;
if (mem_cgroup_disabled())
return 0;
if (PageCompound(page))
return 0;
/*
* Corner case handling. This is called from add_to_page_cache()
* in usual. But some FS (shmem) precharges this page before calling it
* and call add_to_page_cache() with GFP_NOWAIT.
*
* For GFP_NOWAIT case, the page may be pre-charged before calling
* add_to_page_cache(). (See shmem.c) check it here and avoid to call
* charge twice. (It works but has to pay a bit larger cost.)
* And when the page is SwapCache, it should take swap information
* into account. This is under lock_page() now.
*/
if (!(gfp_mask & __GFP_WAIT)) {
struct page_cgroup *pc;
pc = lookup_page_cgroup(page);
if (!pc)
return 0;
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
unlock_page_cgroup(pc);
return 0;
}
unlock_page_cgroup(pc);
}
if (unlikely(!mm && !mem))
mm = &init_mm;
if (page_is_file_cache(page))
return mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
/* shmem */
if (PageSwapCache(page)) {
ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
if (!ret)
__mem_cgroup_commit_charge_swapin(page, mem,
MEM_CGROUP_CHARGE_TYPE_SHMEM);
} else
ret = mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
return ret;
}
/*
* 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()"
*/
int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
struct page *page,
gfp_t mask, struct mem_cgroup **ptr)
{
struct mem_cgroup *mem;
int ret;
if (mem_cgroup_disabled())
return 0;
if (!do_swap_account)
goto charge_cur_mm;
/*
* A racing thread's fault, or swapoff, may have already updated
* the pte, and even removed page from swap cache: in those cases
* do_swap_page()'s pte_same() test will fail; but there's also a
* KSM case which does need to charge the page.
*/
if (!PageSwapCache(page))
goto charge_cur_mm;
mem = try_get_mem_cgroup_from_page(page);
if (!mem)
goto charge_cur_mm;
*ptr = mem;
ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
/* drop extra refcnt from tryget */
css_put(&mem->css);
return ret;
charge_cur_mm:
if (unlikely(!mm))
mm = &init_mm;
return __mem_cgroup_try_charge(mm, mask, ptr, true);
}
static void
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
enum charge_type ctype)
{
struct page_cgroup *pc;
if (mem_cgroup_disabled())
return;
if (!ptr)
return;
cgroup_exclude_rmdir(&ptr->css);
pc = lookup_page_cgroup(page);
mem_cgroup_lru_del_before_commit_swapcache(page);
__mem_cgroup_commit_charge(ptr, pc, ctype);
mem_cgroup_lru_add_after_commit_swapcache(page);
/*
* 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)};
unsigned short id;
struct mem_cgroup *memcg;
id = swap_cgroup_record(ent, 0);
rcu_read_lock();
memcg = mem_cgroup_lookup(id);
if (memcg) {
/*
* This recorded memcg can be obsolete one. So, avoid
* calling css_tryget
*/
if (!mem_cgroup_is_root(memcg))
res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
mem_cgroup_swap_statistics(memcg, false);
mem_cgroup_put(memcg);
}
rcu_read_unlock();
}
/*
* At swapin, we may charge account against cgroup which has no tasks.
* So, rmdir()->pre_destroy() can be called while we do this charge.
* In that case, we need to call pre_destroy() again. check it here.
*/
cgroup_release_and_wakeup_rmdir(&ptr->css);
}
void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
{
__mem_cgroup_commit_charge_swapin(page, ptr,
MEM_CGROUP_CHARGE_TYPE_MAPPED);
}
void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
{
if (mem_cgroup_disabled())
return;
if (!mem)
return;
mem_cgroup_cancel_charge(mem);
}
static void
__do_uncharge(struct mem_cgroup *mem, 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;
/*
* do_batch > 0 when unmapping pages or inode invalidate/truncate.
* In those cases, all pages freed continously 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 (!current->memcg_batch.do_batch || test_thread_flag(TIF_MEMDIE))
goto direct_uncharge;
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 = mem;
/*
* 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 != mem)
goto direct_uncharge;
/* remember freed charge and uncharge it later */
batch->bytes += PAGE_SIZE;
if (uncharge_memsw)
batch->memsw_bytes += PAGE_SIZE;
return;
direct_uncharge:
res_counter_uncharge(&mem->res, PAGE_SIZE);
if (uncharge_memsw)
res_counter_uncharge(&mem->memsw, PAGE_SIZE);
return;
}
/*
* uncharge if !page_mapped(page)
*/
static struct mem_cgroup *
__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
{
struct page_cgroup *pc;
struct mem_cgroup *mem = NULL;
struct mem_cgroup_per_zone *mz;
if (mem_cgroup_disabled())
return NULL;
if (PageSwapCache(page))
return NULL;
/*
* Check if our page_cgroup is valid
*/
pc = lookup_page_cgroup(page);
if (unlikely(!pc || !PageCgroupUsed(pc)))
return NULL;
lock_page_cgroup(pc);
mem = pc->mem_cgroup;
if (!PageCgroupUsed(pc))
goto unlock_out;
switch (ctype) {
case MEM_CGROUP_CHARGE_TYPE_MAPPED:
case MEM_CGROUP_CHARGE_TYPE_DROP:
if (page_mapped(page))
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;
}
if (!mem_cgroup_is_root(mem))
__do_uncharge(mem, ctype);
if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
mem_cgroup_swap_statistics(mem, true);
mem_cgroup_charge_statistics(mem, pc, false);
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.
*/
mz = page_cgroup_zoneinfo(pc);
unlock_page_cgroup(pc);
memcg_check_events(mem, page);
/* at swapout, this memcg will be accessed to record to swap */
if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
css_put(&mem->css);
return mem;
unlock_out:
unlock_page_cgroup(pc);
return NULL;
}
void mem_cgroup_uncharge_page(struct page *page)
{
/* early check. */
if (page_mapped(page))
return;
if (page->mapping && !PageAnon(page))
return;
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
}
void mem_cgroup_uncharge_cache_page(struct page *page)
{
VM_BUG_ON(page_mapped(page));
VM_BUG_ON(page->mapping);
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
}
/*
* 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.bytes = 0;
current->memcg_batch.memsw_bytes = 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->bytes)
res_counter_uncharge(&batch->memcg->res, batch->bytes);
if (batch->memsw_bytes)
res_counter_uncharge(&batch->memcg->memsw, batch->memsw_bytes);
/* 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);
/* record memcg information */
if (do_swap_account && swapout && memcg) {
swap_cgroup_record(ent, css_id(&memcg->css));
mem_cgroup_get(memcg);
}
if (swapout && memcg)
css_put(&memcg->css);
}
#endif
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_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);
mem_cgroup_put(memcg);
}
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
* @need_fixup: whether we should fixup res_counters and refcounts.
*
* 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, bool need_fixup)
{
unsigned short old_id, new_id;
old_id = css_id(&from->css);
new_id = css_id(&to->css);
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 mem_cgroup_get(to)
* because if the process that has been moved to @to does
* swap-in, the refcount of @to might be decreased to 0.
*/
mem_cgroup_get(to);
if (need_fixup) {
if (!mem_cgroup_is_root(from))
res_counter_uncharge(&from->memsw, PAGE_SIZE);
mem_cgroup_put(from);
/*
* we charged both to->res and to->memsw, so we should
* uncharge to->res.
*/
if (!mem_cgroup_is_root(to))
res_counter_uncharge(&to->res, PAGE_SIZE);
css_put(&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, bool need_fixup)
{
return -EINVAL;
}
#endif
/*
* Before starting migration, account PAGE_SIZE to mem_cgroup that the old
* page belongs to.
*/
int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
{
struct page_cgroup *pc;
struct mem_cgroup *mem = NULL;
int ret = 0;
if (mem_cgroup_disabled())
return 0;
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
mem = pc->mem_cgroup;
css_get(&mem->css);
}
unlock_page_cgroup(pc);
*ptr = mem;
if (mem) {
ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false);
css_put(&mem->css);
}
return ret;
}
/* remove redundant charge if migration failed*/
void mem_cgroup_end_migration(struct mem_cgroup *mem,
struct page *oldpage, struct page *newpage)
{
struct page *target, *unused;
struct page_cgroup *pc;
enum charge_type ctype;
if (!mem)
return;
cgroup_exclude_rmdir(&mem->css);
/* at migration success, oldpage->mapping is NULL. */
if (oldpage->mapping) {
target = oldpage;
unused = NULL;
} else {
target = newpage;
unused = oldpage;
}
if (PageAnon(target))
ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
else if (page_is_file_cache(target))
ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
else
ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
/* unused page is not on radix-tree now. */
if (unused)
__mem_cgroup_uncharge_common(unused, ctype);
pc = lookup_page_cgroup(target);
/*
* __mem_cgroup_commit_charge() check PCG_USED bit of page_cgroup.
* So, double-counting is effectively avoided.
*/
__mem_cgroup_commit_charge(mem, pc, ctype);
/*
* Both of oldpage and newpage are still under lock_page().
* Then, we don't have to care about race in radix-tree.
* But we have to be careful that this page is unmapped or not.
*
* There is a case for !page_mapped(). At the start of
* migration, oldpage was mapped. But now, it's zapped.
* But we know *target* page is not freed/reused under us.
* mem_cgroup_uncharge_page() does all necessary checks.
*/
if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
mem_cgroup_uncharge_page(target);
/*
* At migration, we may charge account against cgroup which has no tasks
* So, rmdir()->pre_destroy() can be called while we do this charge.
* In that case, we need to call pre_destroy() again. check it here.
*/
cgroup_release_and_wakeup_rmdir(&mem->css);
}
/*
* A call to try to shrink memory usage on charge failure at shmem's swapin.
* Calling hierarchical_reclaim is not enough because we should update
* last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM.
* Moreover considering hierarchy, we should reclaim from the mem_over_limit,
* not from the memcg which this page would be charged to.
* try_charge_swapin does all of these works properly.
*/
int mem_cgroup_shmem_charge_fallback(struct page *page,
struct mm_struct *mm,
gfp_t gfp_mask)
{
struct mem_cgroup *mem = NULL;
int ret;
if (mem_cgroup_disabled())
return 0;
ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
if (!ret)
mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */
return ret;
}
static DEFINE_MUTEX(set_limit_mutex);
static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
int retry_count;
u64 memswlimit;
int ret = 0;
int children = mem_cgroup_count_children(memcg);
u64 curusage, oldusage;
/*
* 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);
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 mem->res.limit < mem->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;
}
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_hierarchical_reclaim(memcg, NULL, 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;
}
return ret;
}
static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
unsigned long long val)
{
int retry_count;
u64 memlimit, oldusage, curusage;
int children = mem_cgroup_count_children(memcg);
int ret = -EBUSY;
/* 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 mem->res.limit < mem->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;
}
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_hierarchical_reclaim(memcg, NULL, 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;
}
return ret;
}
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
gfp_t gfp_mask, int nid,
int zid)
{
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;
if (order > 0)
return 0;
mctz = soft_limit_tree_node_zone(nid, zid);
/*
* This loop can run a while, specially if mem_cgroup's continuously
* keep exceeding their soft limit and putting the system under
* pressure
*/
do {
if (next_mz)
mz = next_mz;
else
mz = mem_cgroup_largest_soft_limit_node(mctz);
if (!mz)
break;
reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
gfp_mask,
MEM_CGROUP_RECLAIM_SOFT);
nr_reclaimed += reclaimed;
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->mem->css);
next_mz = NULL;
} else /* next_mz == NULL or other memcg */
break;
} while (1);
}
__mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
excess = res_counter_soft_limit_excess(&mz->mem->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->mem, mz, mctz, excess);
spin_unlock(&mctz->lock);
css_put(&mz->mem->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->mem->css);
return nr_reclaimed;
}
/*
* This routine traverse page_cgroup in given list and drop them all.
* *And* this routine doesn't reclaim page itself, just removes page_cgroup.
*/
static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
int node, int zid, enum lru_list lru)
{
struct zone *zone;
struct mem_cgroup_per_zone *mz;
struct page_cgroup *pc, *busy;
unsigned long flags, loop;
struct list_head *list;
int ret = 0;
zone = &NODE_DATA(node)->node_zones[zid];
mz = mem_cgroup_zoneinfo(mem, node, zid);
list = &mz->lists[lru];
loop = MEM_CGROUP_ZSTAT(mz, lru);
/* give some margin against EBUSY etc...*/
loop += 256;
busy = NULL;
while (loop--) {
ret = 0;
spin_lock_irqsave(&zone->lru_lock, flags);
if (list_empty(list)) {
spin_unlock_irqrestore(&zone->lru_lock, flags);
break;
}
pc = list_entry(list->prev, struct page_cgroup, lru);
if (busy == pc) {
list_move(&pc->lru, list);
busy = NULL;
spin_unlock_irqrestore(&zone->lru_lock, flags);
continue;
}
spin_unlock_irqrestore(&zone->lru_lock, flags);
ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
if (ret == -ENOMEM)
break;
if (ret == -EBUSY || ret == -EINVAL) {
/* found lock contention or "pc" is obsolete. */
busy = pc;
cond_resched();
} else
busy = NULL;
}
if (!ret && !list_empty(list))
return -EBUSY;
return ret;
}
/*
* make mem_cgroup's charge to be 0 if there is no task.
* This enables deleting this mem_cgroup.
*/
static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
{
int ret;
int node, zid, shrink;
int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
struct cgroup *cgrp = mem->css.cgroup;
css_get(&mem->css);
shrink = 0;
/* should free all ? */
if (free_all)
goto try_to_free;
move_account:
do {
ret = -EBUSY;
if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
goto out;
ret = -EINTR;
if (signal_pending(current))
goto out;
/* This is for making all *used* pages to be on LRU. */
lru_add_drain_all();
drain_all_stock_sync();
ret = 0;
for_each_node_state(node, N_HIGH_MEMORY) {
for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
enum lru_list l;
for_each_lru(l) {
ret = mem_cgroup_force_empty_list(mem,
node, zid, l);
if (ret)
break;
}
}
if (ret)
break;
}
/* it seems parent cgroup doesn't have enough mem */
if (ret == -ENOMEM)
goto try_to_free;
cond_resched();
/* "ret" should also be checked to ensure all lists are empty. */
} while (mem->res.usage > 0 || ret);
out:
css_put(&mem->css);
return ret;
try_to_free:
/* returns EBUSY if there is a task or if we come here twice. */
if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
ret = -EBUSY;
goto out;
}
/* we call try-to-free pages for make this cgroup empty */
lru_add_drain_all();
/* try to free all pages in this cgroup */
shrink = 1;
while (nr_retries && mem->res.usage > 0) {
int progress;
if (signal_pending(current)) {
ret = -EINTR;
goto out;
}
progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
false, get_swappiness(mem));
if (!progress) {
nr_retries--;
/* maybe some writeback is necessary */
congestion_wait(BLK_RW_ASYNC, HZ/10);
}
}
lru_add_drain();
/* try move_account...there may be some *locked* pages. */
goto move_account;
}
int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
{
return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
}
static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
{
return mem_cgroup_from_cont(cont)->use_hierarchy;
}
static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
u64 val)
{
int retval = 0;
struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
struct cgroup *parent = cont->parent;
struct mem_cgroup *parent_mem = NULL;
if (parent)
parent_mem = mem_cgroup_from_cont(parent);
cgroup_lock();
/*
* 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_mem || !parent_mem->use_hierarchy) &&
(val == 1 || val == 0)) {
if (list_empty(&cont->children))
mem->use_hierarchy = val;
else
retval = -EBUSY;
} else
retval = -EINVAL;
cgroup_unlock();
return retval;
}
struct mem_cgroup_idx_data {
s64 val;
enum mem_cgroup_stat_index idx;
};
static int
mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data)
{
struct mem_cgroup_idx_data *d = data;
d->val += mem_cgroup_read_stat(mem, d->idx);
return 0;
}
static void
mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
enum mem_cgroup_stat_index idx, s64 *val)
{
struct mem_cgroup_idx_data d;
d.idx = idx;
d.val = 0;
mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat);
*val = d.val;
}
static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
{
u64 idx_val, val;
if (!mem_cgroup_is_root(mem)) {
if (!swap)
return res_counter_read_u64(&mem->res, RES_USAGE);
else
return res_counter_read_u64(&mem->memsw, RES_USAGE);