Root/mm/memcontrol.c

1/* memcontrol.c - Memory Controller
2 *
3 * Copyright IBM Corporation, 2007
4 * Author Balbir Singh <balbir@linux.vnet.ibm.com>
5 *
6 * Copyright 2007 OpenVZ SWsoft Inc
7 * Author: Pavel Emelianov <xemul@openvz.org>
8 *
9 * Memory thresholds
10 * Copyright (C) 2009 Nokia Corporation
11 * Author: Kirill A. Shutemov
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 */
23
24#include <linux/res_counter.h>
25#include <linux/memcontrol.h>
26#include <linux/cgroup.h>
27#include <linux/mm.h>
28#include <linux/hugetlb.h>
29#include <linux/pagemap.h>
30#include <linux/smp.h>
31#include <linux/page-flags.h>
32#include <linux/backing-dev.h>
33#include <linux/bit_spinlock.h>
34#include <linux/rcupdate.h>
35#include <linux/limits.h>
36#include <linux/mutex.h>
37#include <linux/rbtree.h>
38#include <linux/slab.h>
39#include <linux/swap.h>
40#include <linux/swapops.h>
41#include <linux/spinlock.h>
42#include <linux/eventfd.h>
43#include <linux/sort.h>
44#include <linux/fs.h>
45#include <linux/seq_file.h>
46#include <linux/vmalloc.h>
47#include <linux/mm_inline.h>
48#include <linux/page_cgroup.h>
49#include <linux/cpu.h>
50#include <linux/oom.h>
51#include "internal.h"
52
53#include <asm/uaccess.h>
54
55#include <trace/events/vmscan.h>
56
57struct cgroup_subsys mem_cgroup_subsys __read_mostly;
58#define MEM_CGROUP_RECLAIM_RETRIES 5
59struct mem_cgroup *root_mem_cgroup __read_mostly;
60
61#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
62/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
63int do_swap_account __read_mostly;
64static int really_do_swap_account __initdata = 1; /* for remember boot option*/
65#else
66#define do_swap_account (0)
67#endif
68
69/*
70 * Per memcg event counter is incremented at every pagein/pageout. This counter
71 * is used for trigger some periodic events. This is straightforward and better
72 * than using jiffies etc. to handle periodic memcg event.
73 *
74 * These values will be used as !((event) & ((1 <<(thresh)) - 1))
75 */
76#define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
77#define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
78
79/*
80 * Statistics for memory cgroup.
81 */
82enum mem_cgroup_stat_index {
83    /*
84     * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
85     */
86    MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */
87    MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */
88    MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */
89    MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */
90    MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */
91    MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
92    MEM_CGROUP_EVENTS, /* incremented at every pagein/pageout */
93
94    MEM_CGROUP_STAT_NSTATS,
95};
96
97struct mem_cgroup_stat_cpu {
98    s64 count[MEM_CGROUP_STAT_NSTATS];
99};
100
101/*
102 * per-zone information in memory controller.
103 */
104struct mem_cgroup_per_zone {
105    /*
106     * spin_lock to protect the per cgroup LRU
107     */
108    struct list_head lists[NR_LRU_LISTS];
109    unsigned long count[NR_LRU_LISTS];
110
111    struct zone_reclaim_stat reclaim_stat;
112    struct rb_node tree_node; /* RB tree node */
113    unsigned long long usage_in_excess;/* Set to the value by which */
114                        /* the soft limit is exceeded*/
115    bool on_tree;
116    struct mem_cgroup *mem; /* Back pointer, we cannot */
117                        /* use container_of */
118};
119/* Macro for accessing counter */
120#define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)])
121
122struct mem_cgroup_per_node {
123    struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
124};
125
126struct mem_cgroup_lru_info {
127    struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
128};
129
130/*
131 * Cgroups above their limits are maintained in a RB-Tree, independent of
132 * their hierarchy representation
133 */
134
135struct mem_cgroup_tree_per_zone {
136    struct rb_root rb_root;
137    spinlock_t lock;
138};
139
140struct mem_cgroup_tree_per_node {
141    struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
142};
143
144struct mem_cgroup_tree {
145    struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
146};
147
148static struct mem_cgroup_tree soft_limit_tree __read_mostly;
149
150struct mem_cgroup_threshold {
151    struct eventfd_ctx *eventfd;
152    u64 threshold;
153};
154
155/* For threshold */
156struct mem_cgroup_threshold_ary {
157    /* An array index points to threshold just below usage. */
158    int current_threshold;
159    /* Size of entries[] */
160    unsigned int size;
161    /* Array of thresholds */
162    struct mem_cgroup_threshold entries[0];
163};
164
165struct mem_cgroup_thresholds {
166    /* Primary thresholds array */
167    struct mem_cgroup_threshold_ary *primary;
168    /*
169     * Spare threshold array.
170     * This is needed to make mem_cgroup_unregister_event() "never fail".
171     * It must be able to store at least primary->size - 1 entries.
172     */
173    struct mem_cgroup_threshold_ary *spare;
174};
175
176/* for OOM */
177struct mem_cgroup_eventfd_list {
178    struct list_head list;
179    struct eventfd_ctx *eventfd;
180};
181
182static void mem_cgroup_threshold(struct mem_cgroup *mem);
183static void mem_cgroup_oom_notify(struct mem_cgroup *mem);
184
185/*
186 * The memory controller data structure. The memory controller controls both
187 * page cache and RSS per cgroup. We would eventually like to provide
188 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
189 * to help the administrator determine what knobs to tune.
190 *
191 * TODO: Add a water mark for the memory controller. Reclaim will begin when
192 * we hit the water mark. May be even add a low water mark, such that
193 * no reclaim occurs from a cgroup at it's low water mark, this is
194 * a feature that will be implemented much later in the future.
195 */
196struct mem_cgroup {
197    struct cgroup_subsys_state css;
198    /*
199     * the counter to account for memory usage
200     */
201    struct res_counter res;
202    /*
203     * the counter to account for mem+swap usage.
204     */
205    struct res_counter memsw;
206    /*
207     * Per cgroup active and inactive list, similar to the
208     * per zone LRU lists.
209     */
210    struct mem_cgroup_lru_info info;
211
212    /*
213      protect against reclaim related member.
214    */
215    spinlock_t reclaim_param_lock;
216
217    /*
218     * While reclaiming in a hierarchy, we cache the last child we
219     * reclaimed from.
220     */
221    int last_scanned_child;
222    /*
223     * Should the accounting and control be hierarchical, per subtree?
224     */
225    bool use_hierarchy;
226    atomic_t oom_lock;
227    atomic_t refcnt;
228
229    unsigned int swappiness;
230    /* OOM-Killer disable */
231    int oom_kill_disable;
232
233    /* set when res.limit == memsw.limit */
234    bool memsw_is_minimum;
235
236    /* protect arrays of thresholds */
237    struct mutex thresholds_lock;
238
239    /* thresholds for memory usage. RCU-protected */
240    struct mem_cgroup_thresholds thresholds;
241
242    /* thresholds for mem+swap usage. RCU-protected */
243    struct mem_cgroup_thresholds memsw_thresholds;
244
245    /* For oom notifier event fd */
246    struct list_head oom_notify;
247
248    /*
249     * Should we move charges of a task when a task is moved into this
250     * mem_cgroup ? And what type of charges should we move ?
251     */
252    unsigned long move_charge_at_immigrate;
253    /*
254     * percpu counter.
255     */
256    struct mem_cgroup_stat_cpu *stat;
257};
258
259/* Stuffs for move charges at task migration. */
260/*
261 * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
262 * left-shifted bitmap of these types.
263 */
264enum move_type {
265    MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
266    MOVE_CHARGE_TYPE_FILE, /* file page(including tmpfs) and swap of it */
267    NR_MOVE_TYPE,
268};
269
270/* "mc" and its members are protected by cgroup_mutex */
271static struct move_charge_struct {
272    spinlock_t lock; /* for from, to, moving_task */
273    struct mem_cgroup *from;
274    struct mem_cgroup *to;
275    unsigned long precharge;
276    unsigned long moved_charge;
277    unsigned long moved_swap;
278    struct task_struct *moving_task; /* a task moving charges */
279    wait_queue_head_t waitq; /* a waitq for other context */
280} mc = {
281    .lock = __SPIN_LOCK_UNLOCKED(mc.lock),
282    .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
283};
284
285static bool move_anon(void)
286{
287    return test_bit(MOVE_CHARGE_TYPE_ANON,
288                    &mc.to->move_charge_at_immigrate);
289}
290
291static bool move_file(void)
292{
293    return test_bit(MOVE_CHARGE_TYPE_FILE,
294                    &mc.to->move_charge_at_immigrate);
295}
296
297/*
298 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
299 * limit reclaim to prevent infinite loops, if they ever occur.
300 */
301#define MEM_CGROUP_MAX_RECLAIM_LOOPS (100)
302#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2)
303
304enum charge_type {
305    MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
306    MEM_CGROUP_CHARGE_TYPE_MAPPED,
307    MEM_CGROUP_CHARGE_TYPE_SHMEM, /* used by page migration of shmem */
308    MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */
309    MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
310    MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */
311    NR_CHARGE_TYPE,
312};
313
314/* only for here (for easy reading.) */
315#define PCGF_CACHE (1UL << PCG_CACHE)
316#define PCGF_USED (1UL << PCG_USED)
317#define PCGF_LOCK (1UL << PCG_LOCK)
318/* Not used, but added here for completeness */
319#define PCGF_ACCT (1UL << PCG_ACCT)
320
321/* for encoding cft->private value on file */
322#define _MEM (0)
323#define _MEMSWAP (1)
324#define _OOM_TYPE (2)
325#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
326#define MEMFILE_TYPE(val) (((val) >> 16) & 0xffff)
327#define MEMFILE_ATTR(val) ((val) & 0xffff)
328/* Used for OOM nofiier */
329#define OOM_CONTROL (0)
330
331/*
332 * Reclaim flags for mem_cgroup_hierarchical_reclaim
333 */
334#define MEM_CGROUP_RECLAIM_NOSWAP_BIT 0x0
335#define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
336#define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1
337#define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
338#define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2
339#define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
340
341static void mem_cgroup_get(struct mem_cgroup *mem);
342static void mem_cgroup_put(struct mem_cgroup *mem);
343static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
344static void drain_all_stock_async(void);
345
346static struct mem_cgroup_per_zone *
347mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
348{
349    return &mem->info.nodeinfo[nid]->zoneinfo[zid];
350}
351
352struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
353{
354    return &mem->css;
355}
356
357static struct mem_cgroup_per_zone *
358page_cgroup_zoneinfo(struct page_cgroup *pc)
359{
360    struct mem_cgroup *mem = pc->mem_cgroup;
361    int nid = page_cgroup_nid(pc);
362    int zid = page_cgroup_zid(pc);
363
364    if (!mem)
365        return NULL;
366
367    return mem_cgroup_zoneinfo(mem, nid, zid);
368}
369
370static struct mem_cgroup_tree_per_zone *
371soft_limit_tree_node_zone(int nid, int zid)
372{
373    return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
374}
375
376static struct mem_cgroup_tree_per_zone *
377soft_limit_tree_from_page(struct page *page)
378{
379    int nid = page_to_nid(page);
380    int zid = page_zonenum(page);
381
382    return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
383}
384
385static void
386__mem_cgroup_insert_exceeded(struct mem_cgroup *mem,
387                struct mem_cgroup_per_zone *mz,
388                struct mem_cgroup_tree_per_zone *mctz,
389                unsigned long long new_usage_in_excess)
390{
391    struct rb_node **p = &mctz->rb_root.rb_node;
392    struct rb_node *parent = NULL;
393    struct mem_cgroup_per_zone *mz_node;
394
395    if (mz->on_tree)
396        return;
397
398    mz->usage_in_excess = new_usage_in_excess;
399    if (!mz->usage_in_excess)
400        return;
401    while (*p) {
402        parent = *p;
403        mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
404                    tree_node);
405        if (mz->usage_in_excess < mz_node->usage_in_excess)
406            p = &(*p)->rb_left;
407        /*
408         * We can't avoid mem cgroups that are over their soft
409         * limit by the same amount
410         */
411        else if (mz->usage_in_excess >= mz_node->usage_in_excess)
412            p = &(*p)->rb_right;
413    }
414    rb_link_node(&mz->tree_node, parent, p);
415    rb_insert_color(&mz->tree_node, &mctz->rb_root);
416    mz->on_tree = true;
417}
418
419static void
420__mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
421                struct mem_cgroup_per_zone *mz,
422                struct mem_cgroup_tree_per_zone *mctz)
423{
424    if (!mz->on_tree)
425        return;
426    rb_erase(&mz->tree_node, &mctz->rb_root);
427    mz->on_tree = false;
428}
429
430static void
431mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
432                struct mem_cgroup_per_zone *mz,
433                struct mem_cgroup_tree_per_zone *mctz)
434{
435    spin_lock(&mctz->lock);
436    __mem_cgroup_remove_exceeded(mem, mz, mctz);
437    spin_unlock(&mctz->lock);
438}
439
440
441static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
442{
443    unsigned long long excess;
444    struct mem_cgroup_per_zone *mz;
445    struct mem_cgroup_tree_per_zone *mctz;
446    int nid = page_to_nid(page);
447    int zid = page_zonenum(page);
448    mctz = soft_limit_tree_from_page(page);
449
450    /*
451     * Necessary to update all ancestors when hierarchy is used.
452     * because their event counter is not touched.
453     */
454    for (; mem; mem = parent_mem_cgroup(mem)) {
455        mz = mem_cgroup_zoneinfo(mem, nid, zid);
456        excess = res_counter_soft_limit_excess(&mem->res);
457        /*
458         * We have to update the tree if mz is on RB-tree or
459         * mem is over its softlimit.
460         */
461        if (excess || mz->on_tree) {
462            spin_lock(&mctz->lock);
463            /* if on-tree, remove it */
464            if (mz->on_tree)
465                __mem_cgroup_remove_exceeded(mem, mz, mctz);
466            /*
467             * Insert again. mz->usage_in_excess will be updated.
468             * If excess is 0, no tree ops.
469             */
470            __mem_cgroup_insert_exceeded(mem, mz, mctz, excess);
471            spin_unlock(&mctz->lock);
472        }
473    }
474}
475
476static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
477{
478    int node, zone;
479    struct mem_cgroup_per_zone *mz;
480    struct mem_cgroup_tree_per_zone *mctz;
481
482    for_each_node_state(node, N_POSSIBLE) {
483        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
484            mz = mem_cgroup_zoneinfo(mem, node, zone);
485            mctz = soft_limit_tree_node_zone(node, zone);
486            mem_cgroup_remove_exceeded(mem, mz, mctz);
487        }
488    }
489}
490
491static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
492{
493    return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
494}
495
496static struct mem_cgroup_per_zone *
497__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
498{
499    struct rb_node *rightmost = NULL;
500    struct mem_cgroup_per_zone *mz;
501
502retry:
503    mz = NULL;
504    rightmost = rb_last(&mctz->rb_root);
505    if (!rightmost)
506        goto done; /* Nothing to reclaim from */
507
508    mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
509    /*
510     * Remove the node now but someone else can add it back,
511     * we will to add it back at the end of reclaim to its correct
512     * position in the tree.
513     */
514    __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
515    if (!res_counter_soft_limit_excess(&mz->mem->res) ||
516        !css_tryget(&mz->mem->css))
517        goto retry;
518done:
519    return mz;
520}
521
522static struct mem_cgroup_per_zone *
523mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
524{
525    struct mem_cgroup_per_zone *mz;
526
527    spin_lock(&mctz->lock);
528    mz = __mem_cgroup_largest_soft_limit_node(mctz);
529    spin_unlock(&mctz->lock);
530    return mz;
531}
532
533static s64 mem_cgroup_read_stat(struct mem_cgroup *mem,
534        enum mem_cgroup_stat_index idx)
535{
536    int cpu;
537    s64 val = 0;
538
539    for_each_possible_cpu(cpu)
540        val += per_cpu(mem->stat->count[idx], cpu);
541    return val;
542}
543
544static s64 mem_cgroup_local_usage(struct mem_cgroup *mem)
545{
546    s64 ret;
547
548    ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
549    ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
550    return ret;
551}
552
553static void mem_cgroup_swap_statistics(struct mem_cgroup *mem,
554                     bool charge)
555{
556    int val = (charge) ? 1 : -1;
557    this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
558}
559
560static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
561                     struct page_cgroup *pc,
562                     bool charge)
563{
564    int val = (charge) ? 1 : -1;
565
566    preempt_disable();
567
568    if (PageCgroupCache(pc))
569        __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_CACHE], val);
570    else
571        __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_RSS], val);
572
573    if (charge)
574        __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
575    else
576        __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
577    __this_cpu_inc(mem->stat->count[MEM_CGROUP_EVENTS]);
578
579    preempt_enable();
580}
581
582static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
583                    enum lru_list idx)
584{
585    int nid, zid;
586    struct mem_cgroup_per_zone *mz;
587    u64 total = 0;
588
589    for_each_online_node(nid)
590        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
591            mz = mem_cgroup_zoneinfo(mem, nid, zid);
592            total += MEM_CGROUP_ZSTAT(mz, idx);
593        }
594    return total;
595}
596
597static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
598{
599    s64 val;
600
601    val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
602
603    return !(val & ((1 << event_mask_shift) - 1));
604}
605
606/*
607 * Check events in order.
608 *
609 */
610static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
611{
612    /* threshold event is triggered in finer grain than soft limit */
613    if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
614        mem_cgroup_threshold(mem);
615        if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
616            mem_cgroup_update_tree(mem, page);
617    }
618}
619
620static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
621{
622    return container_of(cgroup_subsys_state(cont,
623                mem_cgroup_subsys_id), struct mem_cgroup,
624                css);
625}
626
627struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
628{
629    /*
630     * mm_update_next_owner() may clear mm->owner to NULL
631     * if it races with swapoff, page migration, etc.
632     * So this can be called with p == NULL.
633     */
634    if (unlikely(!p))
635        return NULL;
636
637    return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
638                struct mem_cgroup, css);
639}
640
641static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
642{
643    struct mem_cgroup *mem = NULL;
644
645    if (!mm)
646        return NULL;
647    /*
648     * Because we have no locks, mm->owner's may be being moved to other
649     * cgroup. We use css_tryget() here even if this looks
650     * pessimistic (rather than adding locks here).
651     */
652    rcu_read_lock();
653    do {
654        mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
655        if (unlikely(!mem))
656            break;
657    } while (!css_tryget(&mem->css));
658    rcu_read_unlock();
659    return mem;
660}
661
662/*
663 * Call callback function against all cgroup under hierarchy tree.
664 */
665static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
666              int (*func)(struct mem_cgroup *, void *))
667{
668    int found, ret, nextid;
669    struct cgroup_subsys_state *css;
670    struct mem_cgroup *mem;
671
672    if (!root->use_hierarchy)
673        return (*func)(root, data);
674
675    nextid = 1;
676    do {
677        ret = 0;
678        mem = NULL;
679
680        rcu_read_lock();
681        css = css_get_next(&mem_cgroup_subsys, nextid, &root->css,
682                   &found);
683        if (css && css_tryget(css))
684            mem = container_of(css, struct mem_cgroup, css);
685        rcu_read_unlock();
686
687        if (mem) {
688            ret = (*func)(mem, data);
689            css_put(&mem->css);
690        }
691        nextid = found + 1;
692    } while (!ret && css);
693
694    return ret;
695}
696
697static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
698{
699    return (mem == root_mem_cgroup);
700}
701
702/*
703 * Following LRU functions are allowed to be used without PCG_LOCK.
704 * Operations are called by routine of global LRU independently from memcg.
705 * What we have to take care of here is validness of pc->mem_cgroup.
706 *
707 * Changes to pc->mem_cgroup happens when
708 * 1. charge
709 * 2. moving account
710 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
711 * It is added to LRU before charge.
712 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
713 * When moving account, the page is not on LRU. It's isolated.
714 */
715
716void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
717{
718    struct page_cgroup *pc;
719    struct mem_cgroup_per_zone *mz;
720
721    if (mem_cgroup_disabled())
722        return;
723    pc = lookup_page_cgroup(page);
724    /* can happen while we handle swapcache. */
725    if (!TestClearPageCgroupAcctLRU(pc))
726        return;
727    VM_BUG_ON(!pc->mem_cgroup);
728    /*
729     * We don't check PCG_USED bit. It's cleared when the "page" is finally
730     * removed from global LRU.
731     */
732    mz = page_cgroup_zoneinfo(pc);
733    MEM_CGROUP_ZSTAT(mz, lru) -= 1;
734    if (mem_cgroup_is_root(pc->mem_cgroup))
735        return;
736    VM_BUG_ON(list_empty(&pc->lru));
737    list_del_init(&pc->lru);
738    return;
739}
740
741void mem_cgroup_del_lru(struct page *page)
742{
743    mem_cgroup_del_lru_list(page, page_lru(page));
744}
745
746void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
747{
748    struct mem_cgroup_per_zone *mz;
749    struct page_cgroup *pc;
750
751    if (mem_cgroup_disabled())
752        return;
753
754    pc = lookup_page_cgroup(page);
755    /*
756     * Used bit is set without atomic ops but after smp_wmb().
757     * For making pc->mem_cgroup visible, insert smp_rmb() here.
758     */
759    smp_rmb();
760    /* unused or root page is not rotated. */
761    if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
762        return;
763    mz = page_cgroup_zoneinfo(pc);
764    list_move(&pc->lru, &mz->lists[lru]);
765}
766
767void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
768{
769    struct page_cgroup *pc;
770    struct mem_cgroup_per_zone *mz;
771
772    if (mem_cgroup_disabled())
773        return;
774    pc = lookup_page_cgroup(page);
775    VM_BUG_ON(PageCgroupAcctLRU(pc));
776    /*
777     * Used bit is set without atomic ops but after smp_wmb().
778     * For making pc->mem_cgroup visible, insert smp_rmb() here.
779     */
780    smp_rmb();
781    if (!PageCgroupUsed(pc))
782        return;
783
784    mz = page_cgroup_zoneinfo(pc);
785    MEM_CGROUP_ZSTAT(mz, lru) += 1;
786    SetPageCgroupAcctLRU(pc);
787    if (mem_cgroup_is_root(pc->mem_cgroup))
788        return;
789    list_add(&pc->lru, &mz->lists[lru]);
790}
791
792/*
793 * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
794 * lru because the page may.be reused after it's fully uncharged (because of
795 * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
796 * it again. This function is only used to charge SwapCache. It's done under
797 * lock_page and expected that zone->lru_lock is never held.
798 */
799static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
800{
801    unsigned long flags;
802    struct zone *zone = page_zone(page);
803    struct page_cgroup *pc = lookup_page_cgroup(page);
804
805    spin_lock_irqsave(&zone->lru_lock, flags);
806    /*
807     * Forget old LRU when this page_cgroup is *not* used. This Used bit
808     * is guarded by lock_page() because the page is SwapCache.
809     */
810    if (!PageCgroupUsed(pc))
811        mem_cgroup_del_lru_list(page, page_lru(page));
812    spin_unlock_irqrestore(&zone->lru_lock, flags);
813}
814
815static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
816{
817    unsigned long flags;
818    struct zone *zone = page_zone(page);
819    struct page_cgroup *pc = lookup_page_cgroup(page);
820
821    spin_lock_irqsave(&zone->lru_lock, flags);
822    /* link when the page is linked to LRU but page_cgroup isn't */
823    if (PageLRU(page) && !PageCgroupAcctLRU(pc))
824        mem_cgroup_add_lru_list(page, page_lru(page));
825    spin_unlock_irqrestore(&zone->lru_lock, flags);
826}
827
828
829void mem_cgroup_move_lists(struct page *page,
830               enum lru_list from, enum lru_list to)
831{
832    if (mem_cgroup_disabled())
833        return;
834    mem_cgroup_del_lru_list(page, from);
835    mem_cgroup_add_lru_list(page, to);
836}
837
838int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
839{
840    int ret;
841    struct mem_cgroup *curr = NULL;
842    struct task_struct *p;
843
844    p = find_lock_task_mm(task);
845    if (!p)
846        return 0;
847    curr = try_get_mem_cgroup_from_mm(p->mm);
848    task_unlock(p);
849    if (!curr)
850        return 0;
851    /*
852     * We should check use_hierarchy of "mem" not "curr". Because checking
853     * use_hierarchy of "curr" here make this function true if hierarchy is
854     * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
855     * hierarchy(even if use_hierarchy is disabled in "mem").
856     */
857    if (mem->use_hierarchy)
858        ret = css_is_ancestor(&curr->css, &mem->css);
859    else
860        ret = (curr == mem);
861    css_put(&curr->css);
862    return ret;
863}
864
865static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
866{
867    unsigned long active;
868    unsigned long inactive;
869    unsigned long gb;
870    unsigned long inactive_ratio;
871
872    inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_ANON);
873    active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_ANON);
874
875    gb = (inactive + active) >> (30 - PAGE_SHIFT);
876    if (gb)
877        inactive_ratio = int_sqrt(10 * gb);
878    else
879        inactive_ratio = 1;
880
881    if (present_pages) {
882        present_pages[0] = inactive;
883        present_pages[1] = active;
884    }
885
886    return inactive_ratio;
887}
888
889int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
890{
891    unsigned long active;
892    unsigned long inactive;
893    unsigned long present_pages[2];
894    unsigned long inactive_ratio;
895
896    inactive_ratio = calc_inactive_ratio(memcg, present_pages);
897
898    inactive = present_pages[0];
899    active = present_pages[1];
900
901    if (inactive * inactive_ratio < active)
902        return 1;
903
904    return 0;
905}
906
907int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
908{
909    unsigned long active;
910    unsigned long inactive;
911
912    inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE);
913    active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE);
914
915    return (active > inactive);
916}
917
918unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
919                       struct zone *zone,
920                       enum lru_list lru)
921{
922    int nid = zone_to_nid(zone);
923    int zid = zone_idx(zone);
924    struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
925
926    return MEM_CGROUP_ZSTAT(mz, lru);
927}
928
929struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
930                              struct zone *zone)
931{
932    int nid = zone_to_nid(zone);
933    int zid = zone_idx(zone);
934    struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
935
936    return &mz->reclaim_stat;
937}
938
939struct zone_reclaim_stat *
940mem_cgroup_get_reclaim_stat_from_page(struct page *page)
941{
942    struct page_cgroup *pc;
943    struct mem_cgroup_per_zone *mz;
944
945    if (mem_cgroup_disabled())
946        return NULL;
947
948    pc = lookup_page_cgroup(page);
949    /*
950     * Used bit is set without atomic ops but after smp_wmb().
951     * For making pc->mem_cgroup visible, insert smp_rmb() here.
952     */
953    smp_rmb();
954    if (!PageCgroupUsed(pc))
955        return NULL;
956
957    mz = page_cgroup_zoneinfo(pc);
958    if (!mz)
959        return NULL;
960
961    return &mz->reclaim_stat;
962}
963
964unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
965                    struct list_head *dst,
966                    unsigned long *scanned, int order,
967                    int mode, struct zone *z,
968                    struct mem_cgroup *mem_cont,
969                    int active, int file)
970{
971    unsigned long nr_taken = 0;
972    struct page *page;
973    unsigned long scan;
974    LIST_HEAD(pc_list);
975    struct list_head *src;
976    struct page_cgroup *pc, *tmp;
977    int nid = zone_to_nid(z);
978    int zid = zone_idx(z);
979    struct mem_cgroup_per_zone *mz;
980    int lru = LRU_FILE * file + active;
981    int ret;
982
983    BUG_ON(!mem_cont);
984    mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
985    src = &mz->lists[lru];
986
987    scan = 0;
988    list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
989        if (scan >= nr_to_scan)
990            break;
991
992        page = pc->page;
993        if (unlikely(!PageCgroupUsed(pc)))
994            continue;
995        if (unlikely(!PageLRU(page)))
996            continue;
997
998        scan++;
999        ret = __isolate_lru_page(page, mode, file);
1000        switch (ret) {
1001        case 0:
1002            list_move(&page->lru, dst);
1003            mem_cgroup_del_lru(page);
1004            nr_taken++;
1005            break;
1006        case -EBUSY:
1007            /* we don't affect global LRU but rotate in our LRU */
1008            mem_cgroup_rotate_lru_list(page, page_lru(page));
1009            break;
1010        default:
1011            break;
1012        }
1013    }
1014
1015    *scanned = scan;
1016
1017    trace_mm_vmscan_memcg_isolate(0, nr_to_scan, scan, nr_taken,
1018                      0, 0, 0, mode);
1019
1020    return nr_taken;
1021}
1022
1023#define mem_cgroup_from_res_counter(counter, member) \
1024    container_of(counter, struct mem_cgroup, member)
1025
1026static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
1027{
1028    if (do_swap_account) {
1029        if (res_counter_check_under_limit(&mem->res) &&
1030            res_counter_check_under_limit(&mem->memsw))
1031            return true;
1032    } else
1033        if (res_counter_check_under_limit(&mem->res))
1034            return true;
1035    return false;
1036}
1037
1038static unsigned int get_swappiness(struct mem_cgroup *memcg)
1039{
1040    struct cgroup *cgrp = memcg->css.cgroup;
1041    unsigned int swappiness;
1042
1043    /* root ? */
1044    if (cgrp->parent == NULL)
1045        return vm_swappiness;
1046
1047    spin_lock(&memcg->reclaim_param_lock);
1048    swappiness = memcg->swappiness;
1049    spin_unlock(&memcg->reclaim_param_lock);
1050
1051    return swappiness;
1052}
1053
1054/* A routine for testing mem is not under move_account */
1055
1056static bool mem_cgroup_under_move(struct mem_cgroup *mem)
1057{
1058    struct mem_cgroup *from;
1059    struct mem_cgroup *to;
1060    bool ret = false;
1061    /*
1062     * Unlike task_move routines, we access mc.to, mc.from not under
1063     * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
1064     */
1065    spin_lock(&mc.lock);
1066    from = mc.from;
1067    to = mc.to;
1068    if (!from)
1069        goto unlock;
1070    if (from == mem || to == mem
1071        || (mem->use_hierarchy && css_is_ancestor(&from->css, &mem->css))
1072        || (mem->use_hierarchy && css_is_ancestor(&to->css, &mem->css)))
1073        ret = true;
1074unlock:
1075    spin_unlock(&mc.lock);
1076    return ret;
1077}
1078
1079static bool mem_cgroup_wait_acct_move(struct mem_cgroup *mem)
1080{
1081    if (mc.moving_task && current != mc.moving_task) {
1082        if (mem_cgroup_under_move(mem)) {
1083            DEFINE_WAIT(wait);
1084            prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
1085            /* moving charge context might have finished. */
1086            if (mc.moving_task)
1087                schedule();
1088            finish_wait(&mc.waitq, &wait);
1089            return true;
1090        }
1091    }
1092    return false;
1093}
1094
1095static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
1096{
1097    int *val = data;
1098    (*val)++;
1099    return 0;
1100}
1101
1102/**
1103 * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
1104 * @memcg: The memory cgroup that went over limit
1105 * @p: Task that is going to be killed
1106 *
1107 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1108 * enabled
1109 */
1110void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
1111{
1112    struct cgroup *task_cgrp;
1113    struct cgroup *mem_cgrp;
1114    /*
1115     * Need a buffer in BSS, can't rely on allocations. The code relies
1116     * on the assumption that OOM is serialized for memory controller.
1117     * If this assumption is broken, revisit this code.
1118     */
1119    static char memcg_name[PATH_MAX];
1120    int ret;
1121
1122    if (!memcg || !p)
1123        return;
1124
1125
1126    rcu_read_lock();
1127
1128    mem_cgrp = memcg->css.cgroup;
1129    task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
1130
1131    ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
1132    if (ret < 0) {
1133        /*
1134         * Unfortunately, we are unable to convert to a useful name
1135         * But we'll still print out the usage information
1136         */
1137        rcu_read_unlock();
1138        goto done;
1139    }
1140    rcu_read_unlock();
1141
1142    printk(KERN_INFO "Task in %s killed", memcg_name);
1143
1144    rcu_read_lock();
1145    ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
1146    if (ret < 0) {
1147        rcu_read_unlock();
1148        goto done;
1149    }
1150    rcu_read_unlock();
1151
1152    /*
1153     * Continues from above, so we don't need an KERN_ level
1154     */
1155    printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
1156done:
1157
1158    printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
1159        res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
1160        res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
1161        res_counter_read_u64(&memcg->res, RES_FAILCNT));
1162    printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
1163        "failcnt %llu\n",
1164        res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
1165        res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
1166        res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1167}
1168
1169/*
1170 * This function returns the number of memcg under hierarchy tree. Returns
1171 * 1(self count) if no children.
1172 */
1173static int mem_cgroup_count_children(struct mem_cgroup *mem)
1174{
1175    int num = 0;
1176     mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb);
1177    return num;
1178}
1179
1180/*
1181 * Return the memory (and swap, if configured) limit for a memcg.
1182 */
1183u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
1184{
1185    u64 limit;
1186    u64 memsw;
1187
1188    limit = res_counter_read_u64(&memcg->res, RES_LIMIT) +
1189            total_swap_pages;
1190    memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1191    /*
1192     * If memsw is finite and limits the amount of swap space available
1193     * to this memcg, return that limit.
1194     */
1195    return min(limit, memsw);
1196}
1197
1198/*
1199 * Visit the first child (need not be the first child as per the ordering
1200 * of the cgroup list, since we track last_scanned_child) of @mem and use
1201 * that to reclaim free pages from.
1202 */
1203static struct mem_cgroup *
1204mem_cgroup_select_victim(struct mem_cgroup *root_mem)
1205{
1206    struct mem_cgroup *ret = NULL;
1207    struct cgroup_subsys_state *css;
1208    int nextid, found;
1209
1210    if (!root_mem->use_hierarchy) {
1211        css_get(&root_mem->css);
1212        ret = root_mem;
1213    }
1214
1215    while (!ret) {
1216        rcu_read_lock();
1217        nextid = root_mem->last_scanned_child + 1;
1218        css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css,
1219                   &found);
1220        if (css && css_tryget(css))
1221            ret = container_of(css, struct mem_cgroup, css);
1222
1223        rcu_read_unlock();
1224        /* Updates scanning parameter */
1225        spin_lock(&root_mem->reclaim_param_lock);
1226        if (!css) {
1227            /* this means start scan from ID:1 */
1228            root_mem->last_scanned_child = 0;
1229        } else
1230            root_mem->last_scanned_child = found;
1231        spin_unlock(&root_mem->reclaim_param_lock);
1232    }
1233
1234    return ret;
1235}
1236
1237/*
1238 * Scan the hierarchy if needed to reclaim memory. We remember the last child
1239 * we reclaimed from, so that we don't end up penalizing one child extensively
1240 * based on its position in the children list.
1241 *
1242 * root_mem is the original ancestor that we've been reclaim from.
1243 *
1244 * We give up and return to the caller when we visit root_mem twice.
1245 * (other groups can be removed while we're walking....)
1246 *
1247 * If shrink==true, for avoiding to free too much, this returns immedieately.
1248 */
1249static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
1250                        struct zone *zone,
1251                        gfp_t gfp_mask,
1252                        unsigned long reclaim_options)
1253{
1254    struct mem_cgroup *victim;
1255    int ret, total = 0;
1256    int loop = 0;
1257    bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
1258    bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
1259    bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
1260    unsigned long excess = mem_cgroup_get_excess(root_mem);
1261
1262    /* If memsw_is_minimum==1, swap-out is of-no-use. */
1263    if (root_mem->memsw_is_minimum)
1264        noswap = true;
1265
1266    while (1) {
1267        victim = mem_cgroup_select_victim(root_mem);
1268        if (victim == root_mem) {
1269            loop++;
1270            if (loop >= 1)
1271                drain_all_stock_async();
1272            if (loop >= 2) {
1273                /*
1274                 * If we have not been able to reclaim
1275                 * anything, it might because there are
1276                 * no reclaimable pages under this hierarchy
1277                 */
1278                if (!check_soft || !total) {
1279                    css_put(&victim->css);
1280                    break;
1281                }
1282                /*
1283                 * We want to do more targetted reclaim.
1284                 * excess >> 2 is not to excessive so as to
1285                 * reclaim too much, nor too less that we keep
1286                 * coming back to reclaim from this cgroup
1287                 */
1288                if (total >= (excess >> 2) ||
1289                    (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) {
1290                    css_put(&victim->css);
1291                    break;
1292                }
1293            }
1294        }
1295        if (!mem_cgroup_local_usage(victim)) {
1296            /* this cgroup's local usage == 0 */
1297            css_put(&victim->css);
1298            continue;
1299        }
1300        /* we use swappiness of local cgroup */
1301        if (check_soft)
1302            ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
1303                noswap, get_swappiness(victim), zone);
1304        else
1305            ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
1306                        noswap, get_swappiness(victim));
1307        css_put(&victim->css);
1308        /*
1309         * At shrinking usage, we can't check we should stop here or
1310         * reclaim more. It's depends on callers. last_scanned_child
1311         * will work enough for keeping fairness under tree.
1312         */
1313        if (shrink)
1314            return ret;
1315        total += ret;
1316        if (check_soft) {
1317            if (res_counter_check_under_soft_limit(&root_mem->res))
1318                return total;
1319        } else if (mem_cgroup_check_under_limit(root_mem))
1320            return 1 + total;
1321    }
1322    return total;
1323}
1324
1325static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data)
1326{
1327    int *val = (int *)data;
1328    int x;
1329    /*
1330     * Logically, we can stop scanning immediately when we find
1331     * a memcg is already locked. But condidering unlock ops and
1332     * creation/removal of memcg, scan-all is simple operation.
1333     */
1334    x = atomic_inc_return(&mem->oom_lock);
1335    *val = max(x, *val);
1336    return 0;
1337}
1338/*
1339 * Check OOM-Killer is already running under our hierarchy.
1340 * If someone is running, return false.
1341 */
1342static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
1343{
1344    int lock_count = 0;
1345
1346    mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb);
1347
1348    if (lock_count == 1)
1349        return true;
1350    return false;
1351}
1352
1353static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data)
1354{
1355    /*
1356     * When a new child is created while the hierarchy is under oom,
1357     * mem_cgroup_oom_lock() may not be called. We have to use
1358     * atomic_add_unless() here.
1359     */
1360    atomic_add_unless(&mem->oom_lock, -1, 0);
1361    return 0;
1362}
1363
1364static void mem_cgroup_oom_unlock(struct mem_cgroup *mem)
1365{
1366    mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb);
1367}
1368
1369static DEFINE_MUTEX(memcg_oom_mutex);
1370static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1371
1372struct oom_wait_info {
1373    struct mem_cgroup *mem;
1374    wait_queue_t wait;
1375};
1376
1377static int memcg_oom_wake_function(wait_queue_t *wait,
1378    unsigned mode, int sync, void *arg)
1379{
1380    struct mem_cgroup *wake_mem = (struct mem_cgroup *)arg;
1381    struct oom_wait_info *oom_wait_info;
1382
1383    oom_wait_info = container_of(wait, struct oom_wait_info, wait);
1384
1385    if (oom_wait_info->mem == wake_mem)
1386        goto wakeup;
1387    /* if no hierarchy, no match */
1388    if (!oom_wait_info->mem->use_hierarchy || !wake_mem->use_hierarchy)
1389        return 0;
1390    /*
1391     * Both of oom_wait_info->mem and wake_mem are stable under us.
1392     * Then we can use css_is_ancestor without taking care of RCU.
1393     */
1394    if (!css_is_ancestor(&oom_wait_info->mem->css, &wake_mem->css) &&
1395        !css_is_ancestor(&wake_mem->css, &oom_wait_info->mem->css))
1396        return 0;
1397
1398wakeup:
1399    return autoremove_wake_function(wait, mode, sync, arg);
1400}
1401
1402static void memcg_wakeup_oom(struct mem_cgroup *mem)
1403{
1404    /* for filtering, pass "mem" as argument. */
1405    __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, mem);
1406}
1407
1408static void memcg_oom_recover(struct mem_cgroup *mem)
1409{
1410    if (mem && atomic_read(&mem->oom_lock))
1411        memcg_wakeup_oom(mem);
1412}
1413
1414/*
1415 * try to call OOM killer. returns false if we should exit memory-reclaim loop.
1416 */
1417bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
1418{
1419    struct oom_wait_info owait;
1420    bool locked, need_to_kill;
1421
1422    owait.mem = mem;
1423    owait.wait.flags = 0;
1424    owait.wait.func = memcg_oom_wake_function;
1425    owait.wait.private = current;
1426    INIT_LIST_HEAD(&owait.wait.task_list);
1427    need_to_kill = true;
1428    /* At first, try to OOM lock hierarchy under mem.*/
1429    mutex_lock(&memcg_oom_mutex);
1430    locked = mem_cgroup_oom_lock(mem);
1431    /*
1432     * Even if signal_pending(), we can't quit charge() loop without
1433     * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
1434     * under OOM is always welcomed, use TASK_KILLABLE here.
1435     */
1436    prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
1437    if (!locked || mem->oom_kill_disable)
1438        need_to_kill = false;
1439    if (locked)
1440        mem_cgroup_oom_notify(mem);
1441    mutex_unlock(&memcg_oom_mutex);
1442
1443    if (need_to_kill) {
1444        finish_wait(&memcg_oom_waitq, &owait.wait);
1445        mem_cgroup_out_of_memory(mem, mask);
1446    } else {
1447        schedule();
1448        finish_wait(&memcg_oom_waitq, &owait.wait);
1449    }
1450    mutex_lock(&memcg_oom_mutex);
1451    mem_cgroup_oom_unlock(mem);
1452    memcg_wakeup_oom(mem);
1453    mutex_unlock(&memcg_oom_mutex);
1454
1455    if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
1456        return false;
1457    /* Give chance to dying process */
1458    schedule_timeout(1);
1459    return true;
1460}
1461
1462/*
1463 * Currently used to update mapped file statistics, but the routine can be
1464 * generalized to update other statistics as well.
1465 */
1466void mem_cgroup_update_file_mapped(struct page *page, int val)
1467{
1468    struct mem_cgroup *mem;
1469    struct page_cgroup *pc;
1470
1471    pc = lookup_page_cgroup(page);
1472    if (unlikely(!pc))
1473        return;
1474
1475    lock_page_cgroup(pc);
1476    mem = pc->mem_cgroup;
1477    if (!mem || !PageCgroupUsed(pc))
1478        goto done;
1479
1480    /*
1481     * Preemption is already disabled. We can use __this_cpu_xxx
1482     */
1483    if (val > 0) {
1484        __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1485        SetPageCgroupFileMapped(pc);
1486    } else {
1487        __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1488        ClearPageCgroupFileMapped(pc);
1489    }
1490
1491done:
1492    unlock_page_cgroup(pc);
1493}
1494
1495/*
1496 * size of first charge trial. "32" comes from vmscan.c's magic value.
1497 * TODO: maybe necessary to use big numbers in big irons.
1498 */
1499#define CHARGE_SIZE (32 * PAGE_SIZE)
1500struct memcg_stock_pcp {
1501    struct mem_cgroup *cached; /* this never be root cgroup */
1502    int charge;
1503    struct work_struct work;
1504};
1505static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
1506static atomic_t memcg_drain_count;
1507
1508/*
1509 * Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed
1510 * from local stock and true is returned. If the stock is 0 or charges from a
1511 * cgroup which is not current target, returns false. This stock will be
1512 * refilled.
1513 */
1514static bool consume_stock(struct mem_cgroup *mem)
1515{
1516    struct memcg_stock_pcp *stock;
1517    bool ret = true;
1518
1519    stock = &get_cpu_var(memcg_stock);
1520    if (mem == stock->cached && stock->charge)
1521        stock->charge -= PAGE_SIZE;
1522    else /* need to call res_counter_charge */
1523        ret = false;
1524    put_cpu_var(memcg_stock);
1525    return ret;
1526}
1527
1528/*
1529 * Returns stocks cached in percpu to res_counter and reset cached information.
1530 */
1531static void drain_stock(struct memcg_stock_pcp *stock)
1532{
1533    struct mem_cgroup *old = stock->cached;
1534
1535    if (stock->charge) {
1536        res_counter_uncharge(&old->res, stock->charge);
1537        if (do_swap_account)
1538            res_counter_uncharge(&old->memsw, stock->charge);
1539    }
1540    stock->cached = NULL;
1541    stock->charge = 0;
1542}
1543
1544/*
1545 * This must be called under preempt disabled or must be called by
1546 * a thread which is pinned to local cpu.
1547 */
1548static void drain_local_stock(struct work_struct *dummy)
1549{
1550    struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
1551    drain_stock(stock);
1552}
1553
1554/*
1555 * Cache charges(val) which is from res_counter, to local per_cpu area.
1556 * This will be consumed by consume_stock() function, later.
1557 */
1558static void refill_stock(struct mem_cgroup *mem, int val)
1559{
1560    struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
1561
1562    if (stock->cached != mem) { /* reset if necessary */
1563        drain_stock(stock);
1564        stock->cached = mem;
1565    }
1566    stock->charge += val;
1567    put_cpu_var(memcg_stock);
1568}
1569
1570/*
1571 * Tries to drain stocked charges in other cpus. This function is asynchronous
1572 * and just put a work per cpu for draining localy on each cpu. Caller can
1573 * expects some charges will be back to res_counter later but cannot wait for
1574 * it.
1575 */
1576static void drain_all_stock_async(void)
1577{
1578    int cpu;
1579    /* This function is for scheduling "drain" in asynchronous way.
1580     * The result of "drain" is not directly handled by callers. Then,
1581     * if someone is calling drain, we don't have to call drain more.
1582     * Anyway, WORK_STRUCT_PENDING check in queue_work_on() will catch if
1583     * there is a race. We just do loose check here.
1584     */
1585    if (atomic_read(&memcg_drain_count))
1586        return;
1587    /* Notify other cpus that system-wide "drain" is running */
1588    atomic_inc(&memcg_drain_count);
1589    get_online_cpus();
1590    for_each_online_cpu(cpu) {
1591        struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
1592        schedule_work_on(cpu, &stock->work);
1593    }
1594     put_online_cpus();
1595    atomic_dec(&memcg_drain_count);
1596    /* We don't wait for flush_work */
1597}
1598
1599/* This is a synchronous drain interface. */
1600static void drain_all_stock_sync(void)
1601{
1602    /* called when force_empty is called */
1603    atomic_inc(&memcg_drain_count);
1604    schedule_on_each_cpu(drain_local_stock);
1605    atomic_dec(&memcg_drain_count);
1606}
1607
1608static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb,
1609                    unsigned long action,
1610                    void *hcpu)
1611{
1612    int cpu = (unsigned long)hcpu;
1613    struct memcg_stock_pcp *stock;
1614
1615    if (action != CPU_DEAD)
1616        return NOTIFY_OK;
1617    stock = &per_cpu(memcg_stock, cpu);
1618    drain_stock(stock);
1619    return NOTIFY_OK;
1620}
1621
1622
1623/* See __mem_cgroup_try_charge() for details */
1624enum {
1625    CHARGE_OK, /* success */
1626    CHARGE_RETRY, /* need to retry but retry is not bad */
1627    CHARGE_NOMEM, /* we can't do more. return -ENOMEM */
1628    CHARGE_WOULDBLOCK, /* GFP_WAIT wasn't set and no enough res. */
1629    CHARGE_OOM_DIE, /* the current is killed because of OOM */
1630};
1631
1632static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
1633                int csize, bool oom_check)
1634{
1635    struct mem_cgroup *mem_over_limit;
1636    struct res_counter *fail_res;
1637    unsigned long flags = 0;
1638    int ret;
1639
1640    ret = res_counter_charge(&mem->res, csize, &fail_res);
1641
1642    if (likely(!ret)) {
1643        if (!do_swap_account)
1644            return CHARGE_OK;
1645        ret = res_counter_charge(&mem->memsw, csize, &fail_res);
1646        if (likely(!ret))
1647            return CHARGE_OK;
1648
1649        mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
1650        flags |= MEM_CGROUP_RECLAIM_NOSWAP;
1651    } else
1652        mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
1653
1654    if (csize > PAGE_SIZE) /* change csize and retry */
1655        return CHARGE_RETRY;
1656
1657    if (!(gfp_mask & __GFP_WAIT))
1658        return CHARGE_WOULDBLOCK;
1659
1660    ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
1661                    gfp_mask, flags);
1662    /*
1663     * try_to_free_mem_cgroup_pages() might not give us a full
1664     * picture of reclaim. Some pages are reclaimed and might be
1665     * moved to swap cache or just unmapped from the cgroup.
1666     * Check the limit again to see if the reclaim reduced the
1667     * current usage of the cgroup before giving up
1668     */
1669    if (ret || mem_cgroup_check_under_limit(mem_over_limit))
1670        return CHARGE_RETRY;
1671
1672    /*
1673     * At task move, charge accounts can be doubly counted. So, it's
1674     * better to wait until the end of task_move if something is going on.
1675     */
1676    if (mem_cgroup_wait_acct_move(mem_over_limit))
1677        return CHARGE_RETRY;
1678
1679    /* If we don't need to call oom-killer at el, return immediately */
1680    if (!oom_check)
1681        return CHARGE_NOMEM;
1682    /* check OOM */
1683    if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask))
1684        return CHARGE_OOM_DIE;
1685
1686    return CHARGE_RETRY;
1687}
1688
1689/*
1690 * Unlike exported interface, "oom" parameter is added. if oom==true,
1691 * oom-killer can be invoked.
1692 */
1693static int __mem_cgroup_try_charge(struct mm_struct *mm,
1694        gfp_t gfp_mask, struct mem_cgroup **memcg, bool oom)
1695{
1696    int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
1697    struct mem_cgroup *mem = NULL;
1698    int ret;
1699    int csize = CHARGE_SIZE;
1700
1701    /*
1702     * Unlike gloval-vm's OOM-kill, we're not in memory shortage
1703     * in system level. So, allow to go ahead dying process in addition to
1704     * MEMDIE process.
1705     */
1706    if (unlikely(test_thread_flag(TIF_MEMDIE)
1707             || fatal_signal_pending(current)))
1708        goto bypass;
1709
1710    /*
1711     * We always charge the cgroup the mm_struct belongs to.
1712     * The mm_struct's mem_cgroup changes on task migration if the
1713     * thread group leader migrates. It's possible that mm is not
1714     * set, if so charge the init_mm (happens for pagecache usage).
1715     */
1716    if (!*memcg && !mm)
1717        goto bypass;
1718again:
1719    if (*memcg) { /* css should be a valid one */
1720        mem = *memcg;
1721        VM_BUG_ON(css_is_removed(&mem->css));
1722        if (mem_cgroup_is_root(mem))
1723            goto done;
1724        if (consume_stock(mem))
1725            goto done;
1726        css_get(&mem->css);
1727    } else {
1728        struct task_struct *p;
1729
1730        rcu_read_lock();
1731        p = rcu_dereference(mm->owner);
1732        VM_BUG_ON(!p);
1733        /*
1734         * because we don't have task_lock(), "p" can exit while
1735         * we're here. In that case, "mem" can point to root
1736         * cgroup but never be NULL. (and task_struct itself is freed
1737         * by RCU, cgroup itself is RCU safe.) Then, we have small
1738         * risk here to get wrong cgroup. But such kind of mis-account
1739         * by race always happens because we don't have cgroup_mutex().
1740         * It's overkill and we allow that small race, here.
1741         */
1742        mem = mem_cgroup_from_task(p);
1743        VM_BUG_ON(!mem);
1744        if (mem_cgroup_is_root(mem)) {
1745            rcu_read_unlock();
1746            goto done;
1747        }
1748        if (consume_stock(mem)) {
1749            /*
1750             * It seems dagerous to access memcg without css_get().
1751             * But considering how consume_stok works, it's not
1752             * necessary. If consume_stock success, some charges
1753             * from this memcg are cached on this cpu. So, we
1754             * don't need to call css_get()/css_tryget() before
1755             * calling consume_stock().
1756             */
1757            rcu_read_unlock();
1758            goto done;
1759        }
1760        /* after here, we may be blocked. we need to get refcnt */
1761        if (!css_tryget(&mem->css)) {
1762            rcu_read_unlock();
1763            goto again;
1764        }
1765        rcu_read_unlock();
1766    }
1767
1768    do {
1769        bool oom_check;
1770
1771        /* If killed, bypass charge */
1772        if (fatal_signal_pending(current)) {
1773            css_put(&mem->css);
1774            goto bypass;
1775        }
1776
1777        oom_check = false;
1778        if (oom && !nr_oom_retries) {
1779            oom_check = true;
1780            nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
1781        }
1782
1783        ret = __mem_cgroup_do_charge(mem, gfp_mask, csize, oom_check);
1784
1785        switch (ret) {
1786        case CHARGE_OK:
1787            break;
1788        case CHARGE_RETRY: /* not in OOM situation but retry */
1789            csize = PAGE_SIZE;
1790            css_put(&mem->css);
1791            mem = NULL;
1792            goto again;
1793        case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
1794            css_put(&mem->css);
1795            goto nomem;
1796        case CHARGE_NOMEM: /* OOM routine works */
1797            if (!oom) {
1798                css_put(&mem->css);
1799                goto nomem;
1800            }
1801            /* If oom, we never return -ENOMEM */
1802            nr_oom_retries--;
1803            break;
1804        case CHARGE_OOM_DIE: /* Killed by OOM Killer */
1805            css_put(&mem->css);
1806            goto bypass;
1807        }
1808    } while (ret != CHARGE_OK);
1809
1810    if (csize > PAGE_SIZE)
1811        refill_stock(mem, csize - PAGE_SIZE);
1812    css_put(&mem->css);
1813done:
1814    *memcg = mem;
1815    return 0;
1816nomem:
1817    *memcg = NULL;
1818    return -ENOMEM;
1819bypass:
1820    *memcg = NULL;
1821    return 0;
1822}
1823
1824/*
1825 * Somemtimes we have to undo a charge we got by try_charge().
1826 * This function is for that and do uncharge, put css's refcnt.
1827 * gotten by try_charge().
1828 */
1829static void __mem_cgroup_cancel_charge(struct mem_cgroup *mem,
1830                            unsigned long count)
1831{
1832    if (!mem_cgroup_is_root(mem)) {
1833        res_counter_uncharge(&mem->res, PAGE_SIZE * count);
1834        if (do_swap_account)
1835            res_counter_uncharge(&mem->memsw, PAGE_SIZE * count);
1836    }
1837}
1838
1839static void mem_cgroup_cancel_charge(struct mem_cgroup *mem)
1840{
1841    __mem_cgroup_cancel_charge(mem, 1);
1842}
1843
1844/*
1845 * A helper function to get mem_cgroup from ID. must be called under
1846 * rcu_read_lock(). The caller must check css_is_removed() or some if
1847 * it's concern. (dropping refcnt from swap can be called against removed
1848 * memcg.)
1849 */
1850static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
1851{
1852    struct cgroup_subsys_state *css;
1853
1854    /* ID 0 is unused ID */
1855    if (!id)
1856        return NULL;
1857    css = css_lookup(&mem_cgroup_subsys, id);
1858    if (!css)
1859        return NULL;
1860    return container_of(css, struct mem_cgroup, css);
1861}
1862
1863struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
1864{
1865    struct mem_cgroup *mem = NULL;
1866    struct page_cgroup *pc;
1867    unsigned short id;
1868    swp_entry_t ent;
1869
1870    VM_BUG_ON(!PageLocked(page));
1871
1872    pc = lookup_page_cgroup(page);
1873    lock_page_cgroup(pc);
1874    if (PageCgroupUsed(pc)) {
1875        mem = pc->mem_cgroup;
1876        if (mem && !css_tryget(&mem->css))
1877            mem = NULL;
1878    } else if (PageSwapCache(page)) {
1879        ent.val = page_private(page);
1880        id = lookup_swap_cgroup(ent);
1881        rcu_read_lock();
1882        mem = mem_cgroup_lookup(id);
1883        if (mem && !css_tryget(&mem->css))
1884            mem = NULL;
1885        rcu_read_unlock();
1886    }
1887    unlock_page_cgroup(pc);
1888    return mem;
1889}
1890
1891/*
1892 * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
1893 * USED state. If already USED, uncharge and return.
1894 */
1895
1896static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
1897                     struct page_cgroup *pc,
1898                     enum charge_type ctype)
1899{
1900    /* try_charge() can return NULL to *memcg, taking care of it. */
1901    if (!mem)
1902        return;
1903
1904    lock_page_cgroup(pc);
1905    if (unlikely(PageCgroupUsed(pc))) {
1906        unlock_page_cgroup(pc);
1907        mem_cgroup_cancel_charge(mem);
1908        return;
1909    }
1910
1911    pc->mem_cgroup = mem;
1912    /*
1913     * We access a page_cgroup asynchronously without lock_page_cgroup().
1914     * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
1915     * is accessed after testing USED bit. To make pc->mem_cgroup visible
1916     * before USED bit, we need memory barrier here.
1917     * See mem_cgroup_add_lru_list(), etc.
1918      */
1919    smp_wmb();
1920    switch (ctype) {
1921    case MEM_CGROUP_CHARGE_TYPE_CACHE:
1922    case MEM_CGROUP_CHARGE_TYPE_SHMEM:
1923        SetPageCgroupCache(pc);
1924        SetPageCgroupUsed(pc);
1925        break;
1926    case MEM_CGROUP_CHARGE_TYPE_MAPPED:
1927        ClearPageCgroupCache(pc);
1928        SetPageCgroupUsed(pc);
1929        break;
1930    default:
1931        break;
1932    }
1933
1934    mem_cgroup_charge_statistics(mem, pc, true);
1935
1936    unlock_page_cgroup(pc);
1937    /*
1938     * "charge_statistics" updated event counter. Then, check it.
1939     * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
1940     * if they exceeds softlimit.
1941     */
1942    memcg_check_events(mem, pc->page);
1943}
1944
1945/**
1946 * __mem_cgroup_move_account - move account of the page
1947 * @pc: page_cgroup of the page.
1948 * @from: mem_cgroup which the page is moved from.
1949 * @to: mem_cgroup which the page is moved to. @from != @to.
1950 * @uncharge: whether we should call uncharge and css_put against @from.
1951 *
1952 * The caller must confirm following.
1953 * - page is not on LRU (isolate_page() is useful.)
1954 * - the pc is locked, used, and ->mem_cgroup points to @from.
1955 *
1956 * This function doesn't do "charge" nor css_get to new cgroup. It should be
1957 * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
1958 * true, this function does "uncharge" from old cgroup, but it doesn't if
1959 * @uncharge is false, so a caller should do "uncharge".
1960 */
1961
1962static void __mem_cgroup_move_account(struct page_cgroup *pc,
1963    struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
1964{
1965    VM_BUG_ON(from == to);
1966    VM_BUG_ON(PageLRU(pc->page));
1967    VM_BUG_ON(!PageCgroupLocked(pc));
1968    VM_BUG_ON(!PageCgroupUsed(pc));
1969    VM_BUG_ON(pc->mem_cgroup != from);
1970
1971    if (PageCgroupFileMapped(pc)) {
1972        /* Update mapped_file data for mem_cgroup */
1973        preempt_disable();
1974        __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1975        __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1976        preempt_enable();
1977    }
1978    mem_cgroup_charge_statistics(from, pc, false);
1979    if (uncharge)
1980        /* This is not "cancel", but cancel_charge does all we need. */
1981        mem_cgroup_cancel_charge(from);
1982
1983    /* caller should have done css_get */
1984    pc->mem_cgroup = to;
1985    mem_cgroup_charge_statistics(to, pc, true);
1986    /*
1987     * We charges against "to" which may not have any tasks. Then, "to"
1988     * can be under rmdir(). But in current implementation, caller of
1989     * this function is just force_empty() and move charge, so it's
1990     * garanteed that "to" is never removed. So, we don't check rmdir
1991     * status here.
1992     */
1993}
1994
1995/*
1996 * check whether the @pc is valid for moving account and call
1997 * __mem_cgroup_move_account()
1998 */
1999static int mem_cgroup_move_account(struct page_cgroup *pc,
2000        struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
2001{
2002    int ret = -EINVAL;
2003    lock_page_cgroup(pc);
2004    if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
2005        __mem_cgroup_move_account(pc, from, to, uncharge);
2006        ret = 0;
2007    }
2008    unlock_page_cgroup(pc);
2009    /*
2010     * check events
2011     */
2012    memcg_check_events(to, pc->page);
2013    memcg_check_events(from, pc->page);
2014    return ret;
2015}
2016
2017/*
2018 * move charges to its parent.
2019 */
2020
2021static int mem_cgroup_move_parent(struct page_cgroup *pc,
2022                  struct mem_cgroup *child,
2023                  gfp_t gfp_mask)
2024{
2025    struct page *page = pc->page;
2026    struct cgroup *cg = child->css.cgroup;
2027    struct cgroup *pcg = cg->parent;
2028    struct mem_cgroup *parent;
2029    int ret;
2030
2031    /* Is ROOT ? */
2032    if (!pcg)
2033        return -EINVAL;
2034
2035    ret = -EBUSY;
2036    if (!get_page_unless_zero(page))
2037        goto out;
2038    if (isolate_lru_page(page))
2039        goto put;
2040
2041    parent = mem_cgroup_from_cont(pcg);
2042    ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
2043    if (ret || !parent)
2044        goto put_back;
2045
2046    ret = mem_cgroup_move_account(pc, child, parent, true);
2047    if (ret)
2048        mem_cgroup_cancel_charge(parent);
2049put_back:
2050    putback_lru_page(page);
2051put:
2052    put_page(page);
2053out:
2054    return ret;
2055}
2056
2057/*
2058 * Charge the memory controller for page usage.
2059 * Return
2060 * 0 if the charge was successful
2061 * < 0 if the cgroup is over its limit
2062 */
2063static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
2064                gfp_t gfp_mask, enum charge_type ctype)
2065{
2066    struct mem_cgroup *mem = NULL;
2067    struct page_cgroup *pc;
2068    int ret;
2069
2070    pc = lookup_page_cgroup(page);
2071    /* can happen at boot */
2072    if (unlikely(!pc))
2073        return 0;
2074    prefetchw(pc);
2075
2076    ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
2077    if (ret || !mem)
2078        return ret;
2079
2080    __mem_cgroup_commit_charge(mem, pc, ctype);
2081    return 0;
2082}
2083
2084int mem_cgroup_newpage_charge(struct page *page,
2085                  struct mm_struct *mm, gfp_t gfp_mask)
2086{
2087    if (mem_cgroup_disabled())
2088        return 0;
2089    if (PageCompound(page))
2090        return 0;
2091    /*
2092     * If already mapped, we don't have to account.
2093     * If page cache, page->mapping has address_space.
2094     * But page->mapping may have out-of-use anon_vma pointer,
2095     * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
2096     * is NULL.
2097       */
2098    if (page_mapped(page) || (page->mapping && !PageAnon(page)))
2099        return 0;
2100    if (unlikely(!mm))
2101        mm = &init_mm;
2102    return mem_cgroup_charge_common(page, mm, gfp_mask,
2103                MEM_CGROUP_CHARGE_TYPE_MAPPED);
2104}
2105
2106static void
2107__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2108                    enum charge_type ctype);
2109
2110int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
2111                gfp_t gfp_mask)
2112{
2113    int ret;
2114
2115    if (mem_cgroup_disabled())
2116        return 0;
2117    if (PageCompound(page))
2118        return 0;
2119    /*
2120     * Corner case handling. This is called from add_to_page_cache()
2121     * in usual. But some FS (shmem) precharges this page before calling it
2122     * and call add_to_page_cache() with GFP_NOWAIT.
2123     *
2124     * For GFP_NOWAIT case, the page may be pre-charged before calling
2125     * add_to_page_cache(). (See shmem.c) check it here and avoid to call
2126     * charge twice. (It works but has to pay a bit larger cost.)
2127     * And when the page is SwapCache, it should take swap information
2128     * into account. This is under lock_page() now.
2129     */
2130    if (!(gfp_mask & __GFP_WAIT)) {
2131        struct page_cgroup *pc;
2132
2133        pc = lookup_page_cgroup(page);
2134        if (!pc)
2135            return 0;
2136        lock_page_cgroup(pc);
2137        if (PageCgroupUsed(pc)) {
2138            unlock_page_cgroup(pc);
2139            return 0;
2140        }
2141        unlock_page_cgroup(pc);
2142    }
2143
2144    if (unlikely(!mm))
2145        mm = &init_mm;
2146
2147    if (page_is_file_cache(page))
2148        return mem_cgroup_charge_common(page, mm, gfp_mask,
2149                MEM_CGROUP_CHARGE_TYPE_CACHE);
2150
2151    /* shmem */
2152    if (PageSwapCache(page)) {
2153        struct mem_cgroup *mem = NULL;
2154
2155        ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2156        if (!ret)
2157            __mem_cgroup_commit_charge_swapin(page, mem,
2158                    MEM_CGROUP_CHARGE_TYPE_SHMEM);
2159    } else
2160        ret = mem_cgroup_charge_common(page, mm, gfp_mask,
2161                    MEM_CGROUP_CHARGE_TYPE_SHMEM);
2162
2163    return ret;
2164}
2165
2166/*
2167 * While swap-in, try_charge -> commit or cancel, the page is locked.
2168 * And when try_charge() successfully returns, one refcnt to memcg without
2169 * struct page_cgroup is acquired. This refcnt will be consumed by
2170 * "commit()" or removed by "cancel()"
2171 */
2172int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
2173                 struct page *page,
2174                 gfp_t mask, struct mem_cgroup **ptr)
2175{
2176    struct mem_cgroup *mem;
2177    int ret;
2178
2179    if (mem_cgroup_disabled())
2180        return 0;
2181
2182    if (!do_swap_account)
2183        goto charge_cur_mm;
2184    /*
2185     * A racing thread's fault, or swapoff, may have already updated
2186     * the pte, and even removed page from swap cache: in those cases
2187     * do_swap_page()'s pte_same() test will fail; but there's also a
2188     * KSM case which does need to charge the page.
2189     */
2190    if (!PageSwapCache(page))
2191        goto charge_cur_mm;
2192    mem = try_get_mem_cgroup_from_page(page);
2193    if (!mem)
2194        goto charge_cur_mm;
2195    *ptr = mem;
2196    ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
2197    css_put(&mem->css);
2198    return ret;
2199charge_cur_mm:
2200    if (unlikely(!mm))
2201        mm = &init_mm;
2202    return __mem_cgroup_try_charge(mm, mask, ptr, true);
2203}
2204
2205static void
2206__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2207                    enum charge_type ctype)
2208{
2209    struct page_cgroup *pc;
2210
2211    if (mem_cgroup_disabled())
2212        return;
2213    if (!ptr)
2214        return;
2215    cgroup_exclude_rmdir(&ptr->css);
2216    pc = lookup_page_cgroup(page);
2217    mem_cgroup_lru_del_before_commit_swapcache(page);
2218    __mem_cgroup_commit_charge(ptr, pc, ctype);
2219    mem_cgroup_lru_add_after_commit_swapcache(page);
2220    /*
2221     * Now swap is on-memory. This means this page may be
2222     * counted both as mem and swap....double count.
2223     * Fix it by uncharging from memsw. Basically, this SwapCache is stable
2224     * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
2225     * may call delete_from_swap_cache() before reach here.
2226     */
2227    if (do_swap_account && PageSwapCache(page)) {
2228        swp_entry_t ent = {.val = page_private(page)};
2229        unsigned short id;
2230        struct mem_cgroup *memcg;
2231
2232        id = swap_cgroup_record(ent, 0);
2233        rcu_read_lock();
2234        memcg = mem_cgroup_lookup(id);
2235        if (memcg) {
2236            /*
2237             * This recorded memcg can be obsolete one. So, avoid
2238             * calling css_tryget
2239             */
2240            if (!mem_cgroup_is_root(memcg))
2241                res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2242            mem_cgroup_swap_statistics(memcg, false);
2243            mem_cgroup_put(memcg);
2244        }
2245        rcu_read_unlock();
2246    }
2247    /*
2248     * At swapin, we may charge account against cgroup which has no tasks.
2249     * So, rmdir()->pre_destroy() can be called while we do this charge.
2250     * In that case, we need to call pre_destroy() again. check it here.
2251     */
2252    cgroup_release_and_wakeup_rmdir(&ptr->css);
2253}
2254
2255void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
2256{
2257    __mem_cgroup_commit_charge_swapin(page, ptr,
2258                    MEM_CGROUP_CHARGE_TYPE_MAPPED);
2259}
2260
2261void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
2262{
2263    if (mem_cgroup_disabled())
2264        return;
2265    if (!mem)
2266        return;
2267    mem_cgroup_cancel_charge(mem);
2268}
2269
2270static void
2271__do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype)
2272{
2273    struct memcg_batch_info *batch = NULL;
2274    bool uncharge_memsw = true;
2275    /* If swapout, usage of swap doesn't decrease */
2276    if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2277        uncharge_memsw = false;
2278
2279    batch = &current->memcg_batch;
2280    /*
2281     * In usual, we do css_get() when we remember memcg pointer.
2282     * But in this case, we keep res->usage until end of a series of
2283     * uncharges. Then, it's ok to ignore memcg's refcnt.
2284     */
2285    if (!batch->memcg)
2286        batch->memcg = mem;
2287    /*
2288     * do_batch > 0 when unmapping pages or inode invalidate/truncate.
2289     * In those cases, all pages freed continously can be expected to be in
2290     * the same cgroup and we have chance to coalesce uncharges.
2291     * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
2292     * because we want to do uncharge as soon as possible.
2293     */
2294
2295    if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
2296        goto direct_uncharge;
2297
2298    /*
2299     * In typical case, batch->memcg == mem. This means we can
2300     * merge a series of uncharges to an uncharge of res_counter.
2301     * If not, we uncharge res_counter ony by one.
2302     */
2303    if (batch->memcg != mem)
2304        goto direct_uncharge;
2305    /* remember freed charge and uncharge it later */
2306    batch->bytes += PAGE_SIZE;
2307    if (uncharge_memsw)
2308        batch->memsw_bytes += PAGE_SIZE;
2309    return;
2310direct_uncharge:
2311    res_counter_uncharge(&mem->res, PAGE_SIZE);
2312    if (uncharge_memsw)
2313        res_counter_uncharge(&mem->memsw, PAGE_SIZE);
2314    if (unlikely(batch->memcg != mem))
2315        memcg_oom_recover(mem);
2316    return;
2317}
2318
2319/*
2320 * uncharge if !page_mapped(page)
2321 */
2322static struct mem_cgroup *
2323__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
2324{
2325    struct page_cgroup *pc;
2326    struct mem_cgroup *mem = NULL;
2327
2328    if (mem_cgroup_disabled())
2329        return NULL;
2330
2331    if (PageSwapCache(page))
2332        return NULL;
2333
2334    /*
2335     * Check if our page_cgroup is valid
2336     */
2337    pc = lookup_page_cgroup(page);
2338    if (unlikely(!pc || !PageCgroupUsed(pc)))
2339        return NULL;
2340
2341    lock_page_cgroup(pc);
2342
2343    mem = pc->mem_cgroup;
2344
2345    if (!PageCgroupUsed(pc))
2346        goto unlock_out;
2347
2348    switch (ctype) {
2349    case MEM_CGROUP_CHARGE_TYPE_MAPPED:
2350    case MEM_CGROUP_CHARGE_TYPE_DROP:
2351        /* See mem_cgroup_prepare_migration() */
2352        if (page_mapped(page) || PageCgroupMigration(pc))
2353            goto unlock_out;
2354        break;
2355    case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
2356        if (!PageAnon(page)) { /* Shared memory */
2357            if (page->mapping && !page_is_file_cache(page))
2358                goto unlock_out;
2359        } else if (page_mapped(page)) /* Anon */
2360                goto unlock_out;
2361        break;
2362    default:
2363        break;
2364    }
2365
2366    mem_cgroup_charge_statistics(mem, pc, false);
2367
2368    ClearPageCgroupUsed(pc);
2369    /*
2370     * pc->mem_cgroup is not cleared here. It will be accessed when it's
2371     * freed from LRU. This is safe because uncharged page is expected not
2372     * to be reused (freed soon). Exception is SwapCache, it's handled by
2373     * special functions.
2374     */
2375
2376    unlock_page_cgroup(pc);
2377    /*
2378     * even after unlock, we have mem->res.usage here and this memcg
2379     * will never be freed.
2380     */
2381    memcg_check_events(mem, page);
2382    if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
2383        mem_cgroup_swap_statistics(mem, true);
2384        mem_cgroup_get(mem);
2385    }
2386    if (!mem_cgroup_is_root(mem))
2387        __do_uncharge(mem, ctype);
2388
2389    return mem;
2390
2391unlock_out:
2392    unlock_page_cgroup(pc);
2393    return NULL;
2394}
2395
2396void mem_cgroup_uncharge_page(struct page *page)
2397{
2398    /* early check. */
2399    if (page_mapped(page))
2400        return;
2401    if (page->mapping && !PageAnon(page))
2402        return;
2403    __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
2404}
2405
2406void mem_cgroup_uncharge_cache_page(struct page *page)
2407{
2408    VM_BUG_ON(page_mapped(page));
2409    VM_BUG_ON(page->mapping);
2410    __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
2411}
2412
2413/*
2414 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
2415 * In that cases, pages are freed continuously and we can expect pages
2416 * are in the same memcg. All these calls itself limits the number of
2417 * pages freed at once, then uncharge_start/end() is called properly.
2418 * This may be called prural(2) times in a context,
2419 */
2420
2421void mem_cgroup_uncharge_start(void)
2422{
2423    current->memcg_batch.do_batch++;
2424    /* We can do nest. */
2425    if (current->memcg_batch.do_batch == 1) {
2426        current->memcg_batch.memcg = NULL;
2427        current->memcg_batch.bytes = 0;
2428        current->memcg_batch.memsw_bytes = 0;
2429    }
2430}
2431
2432void mem_cgroup_uncharge_end(void)
2433{
2434    struct memcg_batch_info *batch = &current->memcg_batch;
2435
2436    if (!batch->do_batch)
2437        return;
2438
2439    batch->do_batch--;
2440    if (batch->do_batch) /* If stacked, do nothing. */
2441        return;
2442
2443    if (!batch->memcg)
2444        return;
2445    /*
2446     * This "batch->memcg" is valid without any css_get/put etc...
2447     * bacause we hide charges behind us.
2448     */
2449    if (batch->bytes)
2450        res_counter_uncharge(&batch->memcg->res, batch->bytes);
2451    if (batch->memsw_bytes)
2452        res_counter_uncharge(&batch->memcg->memsw, batch->memsw_bytes);
2453    memcg_oom_recover(batch->memcg);
2454    /* forget this pointer (for sanity check) */
2455    batch->memcg = NULL;
2456}
2457
2458#ifdef CONFIG_SWAP
2459/*
2460 * called after __delete_from_swap_cache() and drop "page" account.
2461 * memcg information is recorded to swap_cgroup of "ent"
2462 */
2463void
2464mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
2465{
2466    struct mem_cgroup *memcg;
2467    int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
2468
2469    if (!swapout) /* this was a swap cache but the swap is unused ! */
2470        ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
2471
2472    memcg = __mem_cgroup_uncharge_common(page, ctype);
2473
2474    /*
2475     * record memcg information, if swapout && memcg != NULL,
2476     * mem_cgroup_get() was called in uncharge().
2477     */
2478    if (do_swap_account && swapout && memcg)
2479        swap_cgroup_record(ent, css_id(&memcg->css));
2480}
2481#endif
2482
2483#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2484/*
2485 * called from swap_entry_free(). remove record in swap_cgroup and
2486 * uncharge "memsw" account.
2487 */
2488void mem_cgroup_uncharge_swap(swp_entry_t ent)
2489{
2490    struct mem_cgroup *memcg;
2491    unsigned short id;
2492
2493    if (!do_swap_account)
2494        return;
2495
2496    id = swap_cgroup_record(ent, 0);
2497    rcu_read_lock();
2498    memcg = mem_cgroup_lookup(id);
2499    if (memcg) {
2500        /*
2501         * We uncharge this because swap is freed.
2502         * This memcg can be obsolete one. We avoid calling css_tryget
2503         */
2504        if (!mem_cgroup_is_root(memcg))
2505            res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2506        mem_cgroup_swap_statistics(memcg, false);
2507        mem_cgroup_put(memcg);
2508    }
2509    rcu_read_unlock();
2510}
2511
2512/**
2513 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
2514 * @entry: swap entry to be moved
2515 * @from: mem_cgroup which the entry is moved from
2516 * @to: mem_cgroup which the entry is moved to
2517 * @need_fixup: whether we should fixup res_counters and refcounts.
2518 *
2519 * It succeeds only when the swap_cgroup's record for this entry is the same
2520 * as the mem_cgroup's id of @from.
2521 *
2522 * Returns 0 on success, -EINVAL on failure.
2523 *
2524 * The caller must have charged to @to, IOW, called res_counter_charge() about
2525 * both res and memsw, and called css_get().
2526 */
2527static int mem_cgroup_move_swap_account(swp_entry_t entry,
2528        struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2529{
2530    unsigned short old_id, new_id;
2531
2532    old_id = css_id(&from->css);
2533    new_id = css_id(&to->css);
2534
2535    if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
2536        mem_cgroup_swap_statistics(from, false);
2537        mem_cgroup_swap_statistics(to, true);
2538        /*
2539         * This function is only called from task migration context now.
2540         * It postpones res_counter and refcount handling till the end
2541         * of task migration(mem_cgroup_clear_mc()) for performance
2542         * improvement. But we cannot postpone mem_cgroup_get(to)
2543         * because if the process that has been moved to @to does
2544         * swap-in, the refcount of @to might be decreased to 0.
2545         */
2546        mem_cgroup_get(to);
2547        if (need_fixup) {
2548            if (!mem_cgroup_is_root(from))
2549                res_counter_uncharge(&from->memsw, PAGE_SIZE);
2550            mem_cgroup_put(from);
2551            /*
2552             * we charged both to->res and to->memsw, so we should
2553             * uncharge to->res.
2554             */
2555            if (!mem_cgroup_is_root(to))
2556                res_counter_uncharge(&to->res, PAGE_SIZE);
2557        }
2558        return 0;
2559    }
2560    return -EINVAL;
2561}
2562#else
2563static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
2564        struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2565{
2566    return -EINVAL;
2567}
2568#endif
2569
2570/*
2571 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
2572 * page belongs to.
2573 */
2574int mem_cgroup_prepare_migration(struct page *page,
2575    struct page *newpage, struct mem_cgroup **ptr)
2576{
2577    struct page_cgroup *pc;
2578    struct mem_cgroup *mem = NULL;
2579    enum charge_type ctype;
2580    int ret = 0;
2581
2582    if (mem_cgroup_disabled())
2583        return 0;
2584
2585    pc = lookup_page_cgroup(page);
2586    lock_page_cgroup(pc);
2587    if (PageCgroupUsed(pc)) {
2588        mem = pc->mem_cgroup;
2589        css_get(&mem->css);
2590        /*
2591         * At migrating an anonymous page, its mapcount goes down
2592         * to 0 and uncharge() will be called. But, even if it's fully
2593         * unmapped, migration may fail and this page has to be
2594         * charged again. We set MIGRATION flag here and delay uncharge
2595         * until end_migration() is called
2596         *
2597         * Corner Case Thinking
2598         * A)
2599         * When the old page was mapped as Anon and it's unmap-and-freed
2600         * while migration was ongoing.
2601         * If unmap finds the old page, uncharge() of it will be delayed
2602         * until end_migration(). If unmap finds a new page, it's
2603         * uncharged when it make mapcount to be 1->0. If unmap code
2604         * finds swap_migration_entry, the new page will not be mapped
2605         * and end_migration() will find it(mapcount==0).
2606         *
2607         * B)
2608         * When the old page was mapped but migraion fails, the kernel
2609         * remaps it. A charge for it is kept by MIGRATION flag even
2610         * if mapcount goes down to 0. We can do remap successfully
2611         * without charging it again.
2612         *
2613         * C)
2614         * The "old" page is under lock_page() until the end of
2615         * migration, so, the old page itself will not be swapped-out.
2616         * If the new page is swapped out before end_migraton, our
2617         * hook to usual swap-out path will catch the event.
2618         */
2619        if (PageAnon(page))
2620            SetPageCgroupMigration(pc);
2621    }
2622    unlock_page_cgroup(pc);
2623    /*
2624     * If the page is not charged at this point,
2625     * we return here.
2626     */
2627    if (!mem)
2628        return 0;
2629
2630    *ptr = mem;
2631    ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false);
2632    css_put(&mem->css);/* drop extra refcnt */
2633    if (ret || *ptr == NULL) {
2634        if (PageAnon(page)) {
2635            lock_page_cgroup(pc);
2636            ClearPageCgroupMigration(pc);
2637            unlock_page_cgroup(pc);
2638            /*
2639             * The old page may be fully unmapped while we kept it.
2640             */
2641            mem_cgroup_uncharge_page(page);
2642        }
2643        return -ENOMEM;
2644    }
2645    /*
2646     * We charge new page before it's used/mapped. So, even if unlock_page()
2647     * is called before end_migration, we can catch all events on this new
2648     * page. In the case new page is migrated but not remapped, new page's
2649     * mapcount will be finally 0 and we call uncharge in end_migration().
2650     */
2651    pc = lookup_page_cgroup(newpage);
2652    if (PageAnon(page))
2653        ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
2654    else if (page_is_file_cache(page))
2655        ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
2656    else
2657        ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
2658    __mem_cgroup_commit_charge(mem, pc, ctype);
2659    return ret;
2660}
2661
2662/* remove redundant charge if migration failed*/
2663void mem_cgroup_end_migration(struct mem_cgroup *mem,
2664    struct page *oldpage, struct page *newpage)
2665{
2666    struct page *used, *unused;
2667    struct page_cgroup *pc;
2668
2669    if (!mem)
2670        return;
2671    /* blocks rmdir() */
2672    cgroup_exclude_rmdir(&mem->css);
2673    /* at migration success, oldpage->mapping is NULL. */
2674    if (oldpage->mapping) {
2675        used = oldpage;
2676        unused = newpage;
2677    } else {
2678        used = newpage;
2679        unused = oldpage;
2680    }
2681    /*
2682     * We disallowed uncharge of pages under migration because mapcount
2683     * of the page goes down to zero, temporarly.
2684     * Clear the flag and check the page should be charged.
2685     */
2686    pc = lookup_page_cgroup(oldpage);
2687    lock_page_cgroup(pc);
2688    ClearPageCgroupMigration(pc);
2689    unlock_page_cgroup(pc);
2690
2691    __mem_cgroup_uncharge_common(unused, MEM_CGROUP_CHARGE_TYPE_FORCE);
2692
2693    /*
2694     * If a page is a file cache, radix-tree replacement is very atomic
2695     * and we can skip this check. When it was an Anon page, its mapcount
2696     * goes down to 0. But because we added MIGRATION flage, it's not
2697     * uncharged yet. There are several case but page->mapcount check
2698     * and USED bit check in mem_cgroup_uncharge_page() will do enough
2699     * check. (see prepare_charge() also)
2700     */
2701    if (PageAnon(used))
2702        mem_cgroup_uncharge_page(used);
2703    /*
2704     * At migration, we may charge account against cgroup which has no
2705     * tasks.
2706     * So, rmdir()->pre_destroy() can be called while we do this charge.
2707     * In that case, we need to call pre_destroy() again. check it here.
2708     */
2709    cgroup_release_and_wakeup_rmdir(&mem->css);
2710}
2711
2712/*
2713 * A call to try to shrink memory usage on charge failure at shmem's swapin.
2714 * Calling hierarchical_reclaim is not enough because we should update
2715 * last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM.
2716 * Moreover considering hierarchy, we should reclaim from the mem_over_limit,
2717 * not from the memcg which this page would be charged to.
2718 * try_charge_swapin does all of these works properly.
2719 */
2720int mem_cgroup_shmem_charge_fallback(struct page *page,
2721                struct mm_struct *mm,
2722                gfp_t gfp_mask)
2723{
2724    struct mem_cgroup *mem = NULL;
2725    int ret;
2726
2727    if (mem_cgroup_disabled())
2728        return 0;
2729
2730    ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2731    if (!ret)
2732        mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */
2733
2734    return ret;
2735}
2736
2737static DEFINE_MUTEX(set_limit_mutex);
2738
2739static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
2740                unsigned long long val)
2741{
2742    int retry_count;
2743    u64 memswlimit, memlimit;
2744    int ret = 0;
2745    int children = mem_cgroup_count_children(memcg);
2746    u64 curusage, oldusage;
2747    int enlarge;
2748
2749    /*
2750     * For keeping hierarchical_reclaim simple, how long we should retry
2751     * is depends on callers. We set our retry-count to be function
2752     * of # of children which we should visit in this loop.
2753     */
2754    retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
2755
2756    oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
2757
2758    enlarge = 0;
2759    while (retry_count) {
2760        if (signal_pending(current)) {
2761            ret = -EINTR;
2762            break;
2763        }
2764        /*
2765         * Rather than hide all in some function, I do this in
2766         * open coded manner. You see what this really does.
2767         * We have to guarantee mem->res.limit < mem->memsw.limit.
2768         */
2769        mutex_lock(&set_limit_mutex);
2770        memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
2771        if (memswlimit < val) {
2772            ret = -EINVAL;
2773            mutex_unlock(&set_limit_mutex);
2774            break;
2775        }
2776
2777        memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
2778        if (memlimit < val)
2779            enlarge = 1;
2780
2781        ret = res_counter_set_limit(&memcg->res, val);
2782        if (!ret) {
2783            if (memswlimit == val)
2784                memcg->memsw_is_minimum = true;
2785            else
2786                memcg->memsw_is_minimum = false;
2787        }
2788        mutex_unlock(&set_limit_mutex);
2789
2790        if (!ret)
2791            break;
2792
2793        mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
2794                        MEM_CGROUP_RECLAIM_SHRINK);
2795        curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
2796        /* Usage is reduced ? */
2797          if (curusage >= oldusage)
2798            retry_count--;
2799        else
2800            oldusage = curusage;
2801    }
2802    if (!ret && enlarge)
2803        memcg_oom_recover(memcg);
2804
2805    return ret;
2806}
2807
2808static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
2809                    unsigned long long val)
2810{
2811    int retry_count;
2812    u64 memlimit, memswlimit, oldusage, curusage;
2813    int children = mem_cgroup_count_children(memcg);
2814    int ret = -EBUSY;
2815    int enlarge = 0;
2816
2817    /* see mem_cgroup_resize_res_limit */
2818     retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
2819    oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
2820    while (retry_count) {
2821        if (signal_pending(current)) {
2822            ret = -EINTR;
2823            break;
2824        }
2825        /*
2826         * Rather than hide all in some function, I do this in
2827         * open coded manner. You see what this really does.
2828         * We have to guarantee mem->res.limit < mem->memsw.limit.
2829         */
2830        mutex_lock(&set_limit_mutex);
2831        memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
2832        if (memlimit > val) {
2833            ret = -EINVAL;
2834            mutex_unlock(&set_limit_mutex);
2835            break;
2836        }
2837        memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
2838        if (memswlimit < val)
2839            enlarge = 1;
2840        ret = res_counter_set_limit(&memcg->memsw, val);
2841        if (!ret) {
2842            if (memlimit == val)
2843                memcg->memsw_is_minimum = true;
2844            else
2845                memcg->memsw_is_minimum = false;
2846        }
2847        mutex_unlock(&set_limit_mutex);
2848
2849        if (!ret)
2850            break;
2851
2852        mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
2853                        MEM_CGROUP_RECLAIM_NOSWAP |
2854                        MEM_CGROUP_RECLAIM_SHRINK);
2855        curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
2856        /* Usage is reduced ? */
2857        if (curusage >= oldusage)
2858            retry_count--;
2859        else
2860            oldusage = curusage;
2861    }
2862    if (!ret && enlarge)
2863        memcg_oom_recover(memcg);
2864    return ret;
2865}
2866
2867unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
2868                        gfp_t gfp_mask)
2869{
2870    unsigned long nr_reclaimed = 0;
2871    struct mem_cgroup_per_zone *mz, *next_mz = NULL;
2872    unsigned long reclaimed;
2873    int loop = 0;
2874    struct mem_cgroup_tree_per_zone *mctz;
2875    unsigned long long excess;
2876
2877    if (order > 0)
2878        return 0;
2879
2880    mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
2881    /*
2882     * This loop can run a while, specially if mem_cgroup's continuously
2883     * keep exceeding their soft limit and putting the system under
2884     * pressure
2885     */
2886    do {
2887        if (next_mz)
2888            mz = next_mz;
2889        else
2890            mz = mem_cgroup_largest_soft_limit_node(mctz);
2891        if (!mz)
2892            break;
2893
2894        reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
2895                        gfp_mask,
2896                        MEM_CGROUP_RECLAIM_SOFT);
2897        nr_reclaimed += reclaimed;
2898        spin_lock(&mctz->lock);
2899
2900        /*
2901         * If we failed to reclaim anything from this memory cgroup
2902         * it is time to move on to the next cgroup
2903         */
2904        next_mz = NULL;
2905        if (!reclaimed) {
2906            do {
2907                /*
2908                 * Loop until we find yet another one.
2909                 *
2910                 * By the time we get the soft_limit lock
2911                 * again, someone might have aded the
2912                 * group back on the RB tree. Iterate to
2913                 * make sure we get a different mem.
2914                 * mem_cgroup_largest_soft_limit_node returns
2915                 * NULL if no other cgroup is present on
2916                 * the tree
2917                 */
2918                next_mz =
2919                __mem_cgroup_largest_soft_limit_node(mctz);
2920                if (next_mz == mz) {
2921                    css_put(&next_mz->mem->css);
2922                    next_mz = NULL;
2923                } else /* next_mz == NULL or other memcg */
2924                    break;
2925            } while (1);
2926        }
2927        __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
2928        excess = res_counter_soft_limit_excess(&mz->mem->res);
2929        /*
2930         * One school of thought says that we should not add
2931         * back the node to the tree if reclaim returns 0.
2932         * But our reclaim could return 0, simply because due
2933         * to priority we are exposing a smaller subset of
2934         * memory to reclaim from. Consider this as a longer
2935         * term TODO.
2936         */
2937        /* If excess == 0, no tree ops */
2938        __mem_cgroup_insert_exceeded(mz->mem, mz, mctz, excess);
2939        spin_unlock(&mctz->lock);
2940        css_put(&mz->mem->css);
2941        loop++;
2942        /*
2943         * Could not reclaim anything and there are no more
2944         * mem cgroups to try or we seem to be looping without
2945         * reclaiming anything.
2946         */
2947        if (!nr_reclaimed &&
2948            (next_mz == NULL ||
2949            loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
2950            break;
2951    } while (!nr_reclaimed);
2952    if (next_mz)
2953        css_put(&next_mz->mem->css);
2954    return nr_reclaimed;
2955}
2956
2957/*
2958 * This routine traverse page_cgroup in given list and drop them all.
2959 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
2960 */
2961static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
2962                int node, int zid, enum lru_list lru)
2963{
2964    struct zone *zone;
2965    struct mem_cgroup_per_zone *mz;
2966    struct page_cgroup *pc, *busy;
2967    unsigned long flags, loop;
2968    struct list_head *list;
2969    int ret = 0;
2970
2971    zone = &NODE_DATA(node)->node_zones[zid];
2972    mz = mem_cgroup_zoneinfo(mem, node, zid);
2973    list = &mz->lists[lru];
2974
2975    loop = MEM_CGROUP_ZSTAT(mz, lru);
2976    /* give some margin against EBUSY etc...*/
2977    loop += 256;
2978    busy = NULL;
2979    while (loop--) {
2980        ret = 0;
2981        spin_lock_irqsave(&zone->lru_lock, flags);
2982        if (list_empty(list)) {
2983            spin_unlock_irqrestore(&zone->lru_lock, flags);
2984            break;
2985        }
2986        pc = list_entry(list->prev, struct page_cgroup, lru);
2987        if (busy == pc) {
2988            list_move(&pc->lru, list);
2989            busy = NULL;
2990            spin_unlock_irqrestore(&zone->lru_lock, flags);
2991            continue;
2992        }
2993        spin_unlock_irqrestore(&zone->lru_lock, flags);
2994
2995        ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
2996        if (ret == -ENOMEM)
2997            break;
2998
2999        if (ret == -EBUSY || ret == -EINVAL) {
3000            /* found lock contention or "pc" is obsolete. */
3001            busy = pc;
3002            cond_resched();
3003        } else
3004            busy = NULL;
3005    }
3006
3007    if (!ret && !list_empty(list))
3008        return -EBUSY;
3009    return ret;
3010}
3011
3012/*
3013 * make mem_cgroup's charge to be 0 if there is no task.
3014 * This enables deleting this mem_cgroup.
3015 */
3016static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
3017{
3018    int ret;
3019    int node, zid, shrink;
3020    int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
3021    struct cgroup *cgrp = mem->css.cgroup;
3022
3023    css_get(&mem->css);
3024
3025    shrink = 0;
3026    /* should free all ? */
3027    if (free_all)
3028        goto try_to_free;
3029move_account:
3030    do {
3031        ret = -EBUSY;
3032        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
3033            goto out;
3034        ret = -EINTR;
3035        if (signal_pending(current))
3036            goto out;
3037        /* This is for making all *used* pages to be on LRU. */
3038        lru_add_drain_all();
3039        drain_all_stock_sync();
3040        ret = 0;
3041        for_each_node_state(node, N_HIGH_MEMORY) {
3042            for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
3043                enum lru_list l;
3044                for_each_lru(l) {
3045                    ret = mem_cgroup_force_empty_list(mem,
3046                            node, zid, l);
3047                    if (ret)
3048                        break;
3049                }
3050            }
3051            if (ret)
3052                break;
3053        }
3054        memcg_oom_recover(mem);
3055        /* it seems parent cgroup doesn't have enough mem */
3056        if (ret == -ENOMEM)
3057            goto try_to_free;
3058        cond_resched();
3059    /* "ret" should also be checked to ensure all lists are empty. */
3060    } while (mem->res.usage > 0 || ret);
3061out:
3062    css_put(&mem->css);
3063    return ret;
3064
3065try_to_free:
3066    /* returns EBUSY if there is a task or if we come here twice. */
3067    if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
3068        ret = -EBUSY;
3069        goto out;
3070    }
3071    /* we call try-to-free pages for make this cgroup empty */
3072    lru_add_drain_all();
3073    /* try to free all pages in this cgroup */
3074    shrink = 1;
3075    while (nr_retries && mem->res.usage > 0) {
3076        int progress;
3077
3078        if (signal_pending(current)) {
3079            ret = -EINTR;
3080            goto out;
3081        }
3082        progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
3083                        false, get_swappiness(mem));
3084        if (!progress) {
3085            nr_retries--;
3086            /* maybe some writeback is necessary */
3087            congestion_wait(BLK_RW_ASYNC, HZ/10);
3088        }
3089
3090    }
3091    lru_add_drain();
3092    /* try move_account...there may be some *locked* pages. */
3093    goto move_account;
3094}
3095
3096int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
3097{
3098    return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
3099}
3100
3101
3102static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
3103{
3104    return mem_cgroup_from_cont(cont)->use_hierarchy;
3105}
3106
3107static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
3108                    u64 val)
3109{
3110    int retval = 0;
3111    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3112    struct cgroup *parent = cont->parent;
3113    struct mem_cgroup *parent_mem = NULL;
3114
3115    if (parent)
3116        parent_mem = mem_cgroup_from_cont(parent);
3117
3118    cgroup_lock();
3119    /*
3120     * If parent's use_hierarchy is set, we can't make any modifications
3121     * in the child subtrees. If it is unset, then the change can
3122     * occur, provided the current cgroup has no children.
3123     *
3124     * For the root cgroup, parent_mem is NULL, we allow value to be
3125     * set if there are no children.
3126     */
3127    if ((!parent_mem || !parent_mem->use_hierarchy) &&
3128                (val == 1 || val == 0)) {
3129        if (list_empty(&cont->children))
3130            mem->use_hierarchy = val;
3131        else
3132            retval = -EBUSY;
3133    } else
3134        retval = -EINVAL;
3135    cgroup_unlock();
3136
3137    return retval;
3138}
3139
3140struct mem_cgroup_idx_data {
3141    s64 val;
3142    enum mem_cgroup_stat_index idx;
3143};
3144
3145static int
3146mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data)
3147{
3148    struct mem_cgroup_idx_data *d = data;
3149    d->val += mem_cgroup_read_stat(mem, d->idx);
3150    return 0;
3151}
3152
3153static void
3154mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
3155                enum mem_cgroup_stat_index idx, s64 *val)
3156{
3157    struct mem_cgroup_idx_data d;
3158    d.idx = idx;
3159    d.val = 0;
3160    mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat);
3161    *val = d.val;
3162}
3163
3164static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
3165{
3166    u64 idx_val, val;
3167
3168    if (!mem_cgroup_is_root(mem)) {
3169        if (!swap)
3170            return res_counter_read_u64(&mem->res, RES_USAGE);
3171        else
3172            return res_counter_read_u64(&mem->memsw, RES_USAGE);
3173    }
3174
3175    mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE, &idx_val);
3176    val = idx_val;
3177    mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS, &idx_val);
3178    val += idx_val;
3179
3180    if (swap) {
3181        mem_cgroup_get_recursive_idx_stat(mem,
3182                MEM_CGROUP_STAT_SWAPOUT, &idx_val);
3183        val += idx_val;
3184    }
3185
3186    return val << PAGE_SHIFT;
3187}
3188
3189static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
3190{
3191    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3192    u64 val;
3193    int type, name;
3194
3195    type = MEMFILE_TYPE(cft->private);
3196    name = MEMFILE_ATTR(cft->private);
3197    switch (type) {
3198    case _MEM:
3199        if (name == RES_USAGE)
3200            val = mem_cgroup_usage(mem, false);
3201        else
3202            val = res_counter_read_u64(&mem->res, name);
3203        break;
3204    case _MEMSWAP:
3205        if (name == RES_USAGE)
3206            val = mem_cgroup_usage(mem, true);
3207        else
3208            val = res_counter_read_u64(&mem->memsw, name);
3209        break;
3210    default:
3211        BUG();
3212        break;
3213    }
3214    return val;
3215}
3216/*
3217 * The user of this function is...
3218 * RES_LIMIT.
3219 */
3220static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
3221                const char *buffer)
3222{
3223    struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3224    int type, name;
3225    unsigned long long val;
3226    int ret;
3227
3228    type = MEMFILE_TYPE(cft->private);
3229    name = MEMFILE_ATTR(cft->private);
3230    switch (name) {
3231    case RES_LIMIT:
3232        if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3233            ret = -EINVAL;
3234            break;
3235        }
3236        /* This function does all necessary parse...reuse it */
3237        ret = res_counter_memparse_write_strategy(buffer, &val);
3238        if (ret)
3239            break;
3240        if (type == _MEM)
3241            ret = mem_cgroup_resize_limit(memcg, val);
3242        else
3243            ret = mem_cgroup_resize_memsw_limit(memcg, val);
3244        break;
3245    case RES_SOFT_LIMIT:
3246        ret = res_counter_memparse_write_strategy(buffer, &val);
3247        if (ret)
3248            break;
3249        /*
3250         * For memsw, soft limits are hard to implement in terms
3251         * of semantics, for now, we support soft limits for
3252         * control without swap
3253         */
3254        if (type == _MEM)
3255            ret = res_counter_set_soft_limit(&memcg->res, val);
3256        else
3257            ret = -EINVAL;
3258        break;
3259    default:
3260        ret = -EINVAL; /* should be BUG() ? */
3261        break;
3262    }
3263    return ret;
3264}
3265
3266static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
3267        unsigned long long *mem_limit, unsigned long long *memsw_limit)
3268{
3269    struct cgroup *cgroup;
3270    unsigned long long min_limit, min_memsw_limit, tmp;
3271
3272    min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3273    min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3274    cgroup = memcg->css.cgroup;
3275    if (!memcg->use_hierarchy)
3276        goto out;
3277
3278    while (cgroup->parent) {
3279        cgroup = cgroup->parent;
3280        memcg = mem_cgroup_from_cont(cgroup);
3281        if (!memcg->use_hierarchy)
3282            break;
3283        tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
3284        min_limit = min(min_limit, tmp);
3285        tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3286        min_memsw_limit = min(min_memsw_limit, tmp);
3287    }
3288out:
3289    *mem_limit = min_limit;
3290    *memsw_limit = min_memsw_limit;
3291    return;
3292}
3293
3294static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
3295{
3296    struct mem_cgroup *mem;
3297    int type, name;
3298
3299    mem = mem_cgroup_from_cont(cont);
3300    type = MEMFILE_TYPE(event);
3301    name = MEMFILE_ATTR(event);
3302    switch (name) {
3303    case RES_MAX_USAGE:
3304        if (type == _MEM)
3305            res_counter_reset_max(&mem->res);
3306        else
3307            res_counter_reset_max(&mem->memsw);
3308        break;
3309    case RES_FAILCNT:
3310        if (type == _MEM)
3311            res_counter_reset_failcnt(&mem->res);
3312        else
3313            res_counter_reset_failcnt(&mem->memsw);
3314        break;
3315    }
3316
3317    return 0;
3318}
3319
3320static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
3321                    struct cftype *cft)
3322{
3323    return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
3324}
3325
3326#ifdef CONFIG_MMU
3327static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3328                    struct cftype *cft, u64 val)
3329{
3330    struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3331
3332    if (val >= (1 << NR_MOVE_TYPE))
3333        return -EINVAL;
3334    /*
3335     * We check this value several times in both in can_attach() and
3336     * attach(), so we need cgroup lock to prevent this value from being
3337     * inconsistent.
3338     */
3339    cgroup_lock();
3340    mem->move_charge_at_immigrate = val;
3341    cgroup_unlock();
3342
3343    return 0;
3344}
3345#else
3346static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3347                    struct cftype *cft, u64 val)
3348{
3349    return -ENOSYS;
3350}
3351#endif
3352
3353
3354/* For read statistics */
3355enum {
3356    MCS_CACHE,
3357    MCS_RSS,
3358    MCS_FILE_MAPPED,
3359    MCS_PGPGIN,
3360    MCS_PGPGOUT,
3361    MCS_SWAP,
3362    MCS_INACTIVE_ANON,
3363    MCS_ACTIVE_ANON,
3364    MCS_INACTIVE_FILE,
3365    MCS_ACTIVE_FILE,
3366    MCS_UNEVICTABLE,
3367    NR_MCS_STAT,
3368};
3369
3370struct mcs_total_stat {
3371    s64 stat[NR_MCS_STAT];
3372};
3373
3374struct {
3375    char *local_name;
3376    char *total_name;
3377} memcg_stat_strings[NR_MCS_STAT] = {
3378    {"cache", "total_cache"},
3379    {"rss", "total_rss"},
3380    {"mapped_file", "total_mapped_file"},
3381    {"pgpgin", "total_pgpgin"},
3382    {"pgpgout", "total_pgpgout"},
3383    {"swap", "total_swap"},
3384    {"inactive_anon", "total_inactive_anon"},
3385    {"active_anon", "total_active_anon"},
3386    {"inactive_file", "total_inactive_file"},
3387    {"active_file", "total_active_file"},
3388    {"unevictable", "total_unevictable"}
3389};
3390
3391
3392static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
3393{
3394    struct mcs_total_stat *s = data;
3395    s64 val;
3396
3397    /* per cpu stat */
3398    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
3399    s->stat[MCS_CACHE] += val * PAGE_SIZE;
3400    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
3401    s->stat[MCS_RSS] += val * PAGE_SIZE;
3402    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_MAPPED);
3403    s->stat[MCS_FILE_MAPPED] += val * PAGE_SIZE;
3404    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGIN_COUNT);
3405    s->stat[MCS_PGPGIN] += val;
3406    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGOUT_COUNT);
3407    s->stat[MCS_PGPGOUT] += val;
3408    if (do_swap_account) {
3409        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
3410        s->stat[MCS_SWAP] += val * PAGE_SIZE;
3411    }
3412
3413    /* per zone stat */
3414    val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
3415    s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
3416    val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_ANON);
3417    s->stat[MCS_ACTIVE_ANON] += val * PAGE_SIZE;
3418    val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_FILE);
3419    s->stat[MCS_INACTIVE_FILE] += val * PAGE_SIZE;
3420    val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_FILE);
3421    s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE;
3422    val = mem_cgroup_get_local_zonestat(mem, LRU_UNEVICTABLE);
3423    s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE;
3424    return 0;
3425}
3426
3427static void
3428mem_cgroup_get_total_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
3429{
3430    mem_cgroup_walk_tree(mem, s, mem_cgroup_get_local_stat);
3431}
3432
3433static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
3434                 struct cgroup_map_cb *cb)
3435{
3436    struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
3437    struct mcs_total_stat mystat;
3438    int i;
3439
3440    memset(&mystat, 0, sizeof(mystat));
3441    mem_cgroup_get_local_stat(mem_cont, &mystat);
3442
3443    for (i = 0; i < NR_MCS_STAT; i++) {
3444        if (i == MCS_SWAP && !do_swap_account)
3445            continue;
3446        cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]);
3447    }
3448
3449    /* Hierarchical information */
3450    {
3451        unsigned long long limit, memsw_limit;
3452        memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
3453        cb->fill(cb, "hierarchical_memory_limit", limit);
3454        if (do_swap_account)
3455            cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
3456    }
3457
3458    memset(&mystat, 0, sizeof(mystat));
3459    mem_cgroup_get_total_stat(mem_cont, &mystat);
3460    for (i = 0; i < NR_MCS_STAT; i++) {
3461        if (i == MCS_SWAP && !do_swap_account)
3462            continue;
3463        cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]);
3464    }
3465
3466#ifdef CONFIG_DEBUG_VM
3467    cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
3468
3469    {
3470        int nid, zid;
3471        struct mem_cgroup_per_zone *mz;
3472        unsigned long recent_rotated[2] = {0, 0};
3473        unsigned long recent_scanned[2] = {0, 0};
3474
3475        for_each_online_node(nid)
3476            for (zid = 0; zid < MAX_NR_ZONES; zid++) {
3477                mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
3478
3479                recent_rotated[0] +=
3480                    mz->reclaim_stat.recent_rotated[0];
3481                recent_rotated[1] +=
3482                    mz->reclaim_stat.recent_rotated[1];
3483                recent_scanned[0] +=
3484                    mz->reclaim_stat.recent_scanned[0];
3485                recent_scanned[1] +=
3486                    mz->reclaim_stat.recent_scanned[1];
3487            }
3488        cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
3489        cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
3490        cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
3491        cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
3492    }
3493#endif
3494
3495    return 0;
3496}
3497
3498static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
3499{
3500    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3501
3502    return get_swappiness(memcg);
3503}
3504
3505static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
3506                       u64 val)
3507{
3508    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3509    struct mem_cgroup *parent;
3510
3511    if (val > 100)
3512        return -EINVAL;
3513
3514    if (cgrp->parent == NULL)
3515        return -EINVAL;
3516
3517    parent = mem_cgroup_from_cont(cgrp->parent);
3518
3519    cgroup_lock();
3520
3521    /* If under hierarchy, only empty-root can set this value */
3522    if ((parent->use_hierarchy) ||
3523        (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
3524        cgroup_unlock();
3525        return -EINVAL;
3526    }
3527
3528    spin_lock(&memcg->reclaim_param_lock);
3529    memcg->swappiness = val;
3530    spin_unlock(&memcg->reclaim_param_lock);
3531
3532    cgroup_unlock();
3533
3534    return 0;
3535}
3536
3537static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
3538{
3539    struct mem_cgroup_threshold_ary *t;
3540    u64 usage;
3541    int i;
3542
3543    rcu_read_lock();
3544    if (!swap)
3545        t = rcu_dereference(memcg->thresholds.primary);
3546    else
3547        t = rcu_dereference(memcg->memsw_thresholds.primary);
3548
3549    if (!t)
3550        goto unlock;
3551
3552    usage = mem_cgroup_usage(memcg, swap);
3553
3554    /*
3555     * current_threshold points to threshold just below usage.
3556     * If it's not true, a threshold was crossed after last
3557     * call of __mem_cgroup_threshold().
3558     */
3559    i = t->current_threshold;
3560
3561    /*
3562     * Iterate backward over array of thresholds starting from
3563     * current_threshold and check if a threshold is crossed.
3564     * If none of thresholds below usage is crossed, we read
3565     * only one element of the array here.
3566     */
3567    for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
3568        eventfd_signal(t->entries[i].eventfd, 1);
3569
3570    /* i = current_threshold + 1 */
3571    i++;
3572
3573    /*
3574     * Iterate forward over array of thresholds starting from
3575     * current_threshold+1 and check if a threshold is crossed.
3576     * If none of thresholds above usage is crossed, we read
3577     * only one element of the array here.
3578     */
3579    for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
3580        eventfd_signal(t->entries[i].eventfd, 1);
3581
3582    /* Update current_threshold */
3583    t->current_threshold = i - 1;
3584unlock:
3585    rcu_read_unlock();
3586}
3587
3588static void mem_cgroup_threshold(struct mem_cgroup *memcg)
3589{
3590    while (memcg) {
3591        __mem_cgroup_threshold(memcg, false);
3592        if (do_swap_account)
3593            __mem_cgroup_threshold(memcg, true);
3594
3595        memcg = parent_mem_cgroup(memcg);
3596    }
3597}
3598
3599static int compare_thresholds(const void *a, const void *b)
3600{
3601    const struct mem_cgroup_threshold *_a = a;
3602    const struct mem_cgroup_threshold *_b = b;
3603
3604    return _a->threshold - _b->threshold;
3605}
3606
3607static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem, void *data)
3608{
3609    struct mem_cgroup_eventfd_list *ev;
3610
3611    list_for_each_entry(ev, &mem->oom_notify, list)
3612        eventfd_signal(ev->eventfd, 1);
3613    return 0;
3614}
3615
3616static void mem_cgroup_oom_notify(struct mem_cgroup *mem)
3617{
3618    mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_notify_cb);
3619}
3620
3621static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
3622    struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
3623{
3624    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3625    struct mem_cgroup_thresholds *thresholds;
3626    struct mem_cgroup_threshold_ary *new;
3627    int type = MEMFILE_TYPE(cft->private);
3628    u64 threshold, usage;
3629    int i, size, ret;
3630
3631    ret = res_counter_memparse_write_strategy(args, &threshold);
3632    if (ret)
3633        return ret;
3634
3635    mutex_lock(&memcg->thresholds_lock);
3636
3637    if (type == _MEM)
3638        thresholds = &memcg->thresholds;
3639    else if (type == _MEMSWAP)
3640        thresholds = &memcg->memsw_thresholds;
3641    else
3642        BUG();
3643
3644    usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3645
3646    /* Check if a threshold crossed before adding a new one */
3647    if (thresholds->primary)
3648        __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3649
3650    size = thresholds->primary ? thresholds->primary->size + 1 : 1;
3651
3652    /* Allocate memory for new array of thresholds */
3653    new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
3654            GFP_KERNEL);
3655    if (!new) {
3656        ret = -ENOMEM;
3657        goto unlock;
3658    }
3659    new->size = size;
3660
3661    /* Copy thresholds (if any) to new array */
3662    if (thresholds->primary) {
3663        memcpy(new->entries, thresholds->primary->entries, (size - 1) *
3664                sizeof(struct mem_cgroup_threshold));
3665    }
3666
3667    /* Add new threshold */
3668    new->entries[size - 1].eventfd = eventfd;
3669    new->entries[size - 1].threshold = threshold;
3670
3671    /* Sort thresholds. Registering of new threshold isn't time-critical */
3672    sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
3673            compare_thresholds, NULL);
3674
3675    /* Find current threshold */
3676    new->current_threshold = -1;
3677    for (i = 0; i < size; i++) {
3678        if (new->entries[i].threshold < usage) {
3679            /*
3680             * new->current_threshold will not be used until
3681             * rcu_assign_pointer(), so it's safe to increment
3682             * it here.
3683             */
3684            ++new->current_threshold;
3685        }
3686    }
3687
3688    /* Free old spare buffer and save old primary buffer as spare */
3689    kfree(thresholds->spare);
3690    thresholds->spare = thresholds->primary;
3691
3692    rcu_assign_pointer(thresholds->primary, new);
3693
3694    /* To be sure that nobody uses thresholds */
3695    synchronize_rcu();
3696
3697unlock:
3698    mutex_unlock(&memcg->thresholds_lock);
3699
3700    return ret;
3701}
3702
3703static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
3704    struct cftype *cft, struct eventfd_ctx *eventfd)
3705{
3706    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3707    struct mem_cgroup_thresholds *thresholds;
3708    struct mem_cgroup_threshold_ary *new;
3709    int type = MEMFILE_TYPE(cft->private);
3710    u64 usage;
3711    int i, j, size;
3712
3713    mutex_lock(&memcg->thresholds_lock);
3714    if (type == _MEM)
3715        thresholds = &memcg->thresholds;
3716    else if (type == _MEMSWAP)
3717        thresholds = &memcg->memsw_thresholds;
3718    else
3719        BUG();
3720
3721    /*
3722     * Something went wrong if we trying to unregister a threshold
3723     * if we don't have thresholds
3724     */
3725    BUG_ON(!thresholds);
3726
3727    usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3728
3729    /* Check if a threshold crossed before removing */
3730    __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3731
3732    /* Calculate new number of threshold */
3733    size = 0;
3734    for (i = 0; i < thresholds->primary->size; i++) {
3735        if (thresholds->primary->entries[i].eventfd != eventfd)
3736            size++;
3737    }
3738
3739    new = thresholds->spare;
3740
3741    /* Set thresholds array to NULL if we don't have thresholds */
3742    if (!size) {
3743        kfree(new);
3744        new = NULL;
3745        goto swap_buffers;
3746    }
3747
3748    new->size = size;
3749
3750    /* Copy thresholds and find current threshold */
3751    new->current_threshold = -1;
3752    for (i = 0, j = 0; i < thresholds->primary->size; i++) {
3753        if (thresholds->primary->entries[i].eventfd == eventfd)
3754            continue;
3755
3756        new->entries[j] = thresholds->primary->entries[i];
3757        if (new->entries[j].threshold < usage) {
3758            /*
3759             * new->current_threshold will not be used
3760             * until rcu_assign_pointer(), so it's safe to increment
3761             * it here.
3762             */
3763            ++new->current_threshold;
3764        }
3765        j++;
3766    }
3767
3768swap_buffers:
3769    /* Swap primary and spare array */
3770    thresholds->spare = thresholds->primary;
3771    rcu_assign_pointer(thresholds->primary, new);
3772
3773    /* To be sure that nobody uses thresholds */
3774    synchronize_rcu();
3775
3776    mutex_unlock(&memcg->thresholds_lock);
3777}
3778
3779static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
3780    struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
3781{
3782    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3783    struct mem_cgroup_eventfd_list *event;
3784    int type = MEMFILE_TYPE(cft->private);
3785
3786    BUG_ON(type != _OOM_TYPE);
3787    event = kmalloc(sizeof(*event), GFP_KERNEL);
3788    if (!event)
3789        return -ENOMEM;
3790
3791    mutex_lock(&memcg_oom_mutex);
3792
3793    event->eventfd = eventfd;
3794    list_add(&event->list, &memcg->oom_notify);
3795
3796    /* already in OOM ? */
3797    if (atomic_read(&memcg->oom_lock))
3798        eventfd_signal(eventfd, 1);
3799    mutex_unlock(&memcg_oom_mutex);
3800
3801    return 0;
3802}
3803
3804static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
3805    struct cftype *cft, struct eventfd_ctx *eventfd)
3806{
3807    struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3808    struct mem_cgroup_eventfd_list *ev, *tmp;
3809    int type = MEMFILE_TYPE(cft->private);
3810
3811    BUG_ON(type != _OOM_TYPE);
3812
3813    mutex_lock(&memcg_oom_mutex);
3814
3815    list_for_each_entry_safe(ev, tmp, &mem->oom_notify, list) {
3816        if (ev->eventfd == eventfd) {
3817            list_del(&ev->list);
3818            kfree(ev);
3819        }
3820    }
3821
3822    mutex_unlock(&memcg_oom_mutex);
3823}
3824
3825static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
3826    struct cftype *cft, struct cgroup_map_cb *cb)
3827{
3828    struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3829
3830    cb->fill(cb, "oom_kill_disable", mem->oom_kill_disable);
3831
3832    if (atomic_read(&mem->oom_lock))
3833        cb->fill(cb, "under_oom", 1);
3834    else
3835        cb->fill(cb, "under_oom", 0);
3836    return 0;
3837}
3838
3839static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
3840    struct cftype *cft, u64 val)
3841{
3842    struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3843    struct mem_cgroup *parent;
3844
3845    /* cannot set to root cgroup and only 0 and 1 are allowed */
3846    if (!cgrp->parent || !((val == 0) || (val == 1)))
3847        return -EINVAL;
3848
3849    parent = mem_cgroup_from_cont(cgrp->parent);
3850
3851    cgroup_lock();
3852    /* oom-kill-disable is a flag for subhierarchy. */
3853    if ((parent->use_hierarchy) ||
3854        (mem->use_hierarchy && !list_empty(&cgrp->children))) {
3855        cgroup_unlock();
3856        return -EINVAL;
3857    }
3858    mem->oom_kill_disable = val;
3859    if (!val)
3860        memcg_oom_recover(mem);
3861    cgroup_unlock();
3862    return 0;
3863}
3864
3865static struct cftype mem_cgroup_files[] = {
3866    {
3867        .name = "usage_in_bytes",
3868        .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
3869        .read_u64 = mem_cgroup_read,
3870        .register_event = mem_cgroup_usage_register_event,
3871        .unregister_event = mem_cgroup_usage_unregister_event,
3872    },
3873    {
3874        .name = "max_usage_in_bytes",
3875        .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
3876        .trigger = mem_cgroup_reset,
3877        .read_u64 = mem_cgroup_read,
3878    },
3879    {
3880        .name = "limit_in_bytes",
3881        .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
3882        .write_string = mem_cgroup_write,
3883        .read_u64 = mem_cgroup_read,
3884    },
3885    {
3886        .name = "soft_limit_in_bytes",
3887        .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
3888        .write_string = mem_cgroup_write,
3889        .read_u64 = mem_cgroup_read,
3890    },
3891    {
3892        .name = "failcnt",
3893        .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
3894        .trigger = mem_cgroup_reset,
3895        .read_u64 = mem_cgroup_read,
3896    },
3897    {
3898        .name = "stat",
3899        .read_map = mem_control_stat_show,
3900    },
3901    {
3902        .name = "force_empty",
3903        .trigger = mem_cgroup_force_empty_write,
3904    },
3905    {
3906        .name = "use_hierarchy",
3907        .write_u64 = mem_cgroup_hierarchy_write,
3908        .read_u64 = mem_cgroup_hierarchy_read,
3909    },
3910    {
3911        .name = "swappiness",
3912        .read_u64 = mem_cgroup_swappiness_read,
3913        .write_u64 = mem_cgroup_swappiness_write,
3914    },
3915    {
3916        .name = "move_charge_at_immigrate",
3917        .read_u64 = mem_cgroup_move_charge_read,
3918        .write_u64 = mem_cgroup_move_charge_write,
3919    },
3920    {
3921        .name = "oom_control",
3922        .read_map = mem_cgroup_oom_control_read,
3923        .write_u64 = mem_cgroup_oom_control_write,
3924        .register_event = mem_cgroup_oom_register_event,
3925        .unregister_event = mem_cgroup_oom_unregister_event,
3926        .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
3927    },
3928};
3929
3930#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
3931static struct cftype memsw_cgroup_files[] = {
3932    {
3933        .name = "memsw.usage_in_bytes",
3934        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
3935        .read_u64 = mem_cgroup_read,
3936        .register_event = mem_cgroup_usage_register_event,
3937        .unregister_event = mem_cgroup_usage_unregister_event,
3938    },
3939    {
3940        .name = "memsw.max_usage_in_bytes",
3941        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
3942        .trigger = mem_cgroup_reset,
3943        .read_u64 = mem_cgroup_read,
3944    },
3945    {
3946        .name = "memsw.limit_in_bytes",
3947        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
3948        .write_string = mem_cgroup_write,
3949        .read_u64 = mem_cgroup_read,
3950    },
3951    {
3952        .name = "memsw.failcnt",
3953        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
3954        .trigger = mem_cgroup_reset,
3955        .read_u64 = mem_cgroup_read,
3956    },
3957};
3958
3959static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
3960{
3961    if (!do_swap_account)
3962        return 0;
3963    return cgroup_add_files(cont, ss, memsw_cgroup_files,
3964                ARRAY_SIZE(memsw_cgroup_files));
3965};
3966#else
3967static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
3968{
3969    return 0;
3970}
3971#endif
3972
3973static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
3974{
3975    struct mem_cgroup_per_node *pn;
3976    struct mem_cgroup_per_zone *mz;
3977    enum lru_list l;
3978    int zone, tmp = node;
3979    /*
3980     * This routine is called against possible nodes.
3981     * But it's BUG to call kmalloc() against offline node.
3982     *
3983     * TODO: this routine can waste much memory for nodes which will
3984     * never be onlined. It's better to use memory hotplug callback
3985     * function.
3986     */
3987    if (!node_state(node, N_NORMAL_MEMORY))
3988        tmp = -1;
3989    pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
3990    if (!pn)
3991        return 1;
3992
3993    mem->info.nodeinfo[node] = pn;
3994    memset(pn, 0, sizeof(*pn));
3995
3996    for (zone = 0; zone < MAX_NR_ZONES; zone++) {
3997        mz = &pn->zoneinfo[zone];
3998        for_each_lru(l)
3999            INIT_LIST_HEAD(&mz->lists[l]);
4000        mz->usage_in_excess = 0;
4001        mz->on_tree = false;
4002        mz->mem = mem;
4003    }
4004    return 0;
4005}
4006
4007static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
4008{
4009    kfree(mem->info.nodeinfo[node]);
4010}
4011
4012static struct mem_cgroup *mem_cgroup_alloc(void)
4013{
4014    struct mem_cgroup *mem;
4015    int size = sizeof(struct mem_cgroup);
4016
4017    /* Can be very big if MAX_NUMNODES is very big */
4018    if (size < PAGE_SIZE)
4019        mem = kmalloc(size, GFP_KERNEL);
4020    else
4021        mem = vmalloc(size);
4022
4023    if (!mem)
4024        return NULL;
4025
4026    memset(mem, 0, size);
4027    mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
4028    if (!mem->stat) {
4029        if (size < PAGE_SIZE)
4030            kfree(mem);
4031        else
4032            vfree(mem);
4033        mem = NULL;
4034    }
4035    return mem;
4036}
4037
4038/*
4039 * At destroying mem_cgroup, references from swap_cgroup can remain.
4040 * (scanning all at force_empty is too costly...)
4041 *
4042 * Instead of clearing all references at force_empty, we remember
4043 * the number of reference from swap_cgroup and free mem_cgroup when
4044 * it goes down to 0.
4045 *
4046 * Removal of cgroup itself succeeds regardless of refs from swap.
4047 */
4048
4049static void __mem_cgroup_free(struct mem_cgroup *mem)
4050{
4051    int node;
4052
4053    mem_cgroup_remove_from_trees(mem);
4054    free_css_id(&mem_cgroup_subsys, &mem->css);
4055
4056    for_each_node_state(node, N_POSSIBLE)
4057        free_mem_cgroup_per_zone_info(mem, node);
4058
4059    free_percpu(mem->stat);
4060    if (sizeof(struct mem_cgroup) < PAGE_SIZE)
4061        kfree(mem);
4062    else
4063        vfree(mem);
4064}
4065
4066static void mem_cgroup_get(struct mem_cgroup *mem)
4067{
4068    atomic_inc(&mem->refcnt);
4069}
4070
4071static void __mem_cgroup_put(struct mem_cgroup *mem, int count)
4072{
4073    if (atomic_sub_and_test(count, &mem->refcnt)) {
4074        struct mem_cgroup *parent = parent_mem_cgroup(mem);
4075        __mem_cgroup_free(mem);
4076        if (parent)
4077            mem_cgroup_put(parent);
4078    }
4079}
4080
4081static void mem_cgroup_put(struct mem_cgroup *mem)
4082{
4083    __mem_cgroup_put(mem, 1);
4084}
4085
4086/*
4087 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
4088 */
4089static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem)
4090{
4091    if (!mem->res.parent)
4092        return NULL;
4093    return mem_cgroup_from_res_counter(mem->res.parent, res);
4094}
4095
4096#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4097static void __init enable_swap_cgroup(void)
4098{
4099    if (!mem_cgroup_disabled() && really_do_swap_account)
4100        do_swap_account = 1;
4101}
4102#else
4103static void __init enable_swap_cgroup(void)
4104{
4105}
4106#endif
4107
4108static int mem_cgroup_soft_limit_tree_init(void)
4109{
4110    struct mem_cgroup_tree_per_node *rtpn;
4111    struct mem_cgroup_tree_per_zone *rtpz;
4112    int tmp, node, zone;
4113
4114    for_each_node_state(node, N_POSSIBLE) {
4115        tmp = node;
4116        if (!node_state(node, N_NORMAL_MEMORY))
4117            tmp = -1;
4118        rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
4119        if (!rtpn)
4120            return 1;
4121
4122        soft_limit_tree.rb_tree_per_node[node] = rtpn;
4123
4124        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4125            rtpz = &rtpn->rb_tree_per_zone[zone];
4126            rtpz->rb_root = RB_ROOT;
4127            spin_lock_init(&rtpz->lock);
4128        }
4129    }
4130    return 0;
4131}
4132
4133static struct cgroup_subsys_state * __ref
4134mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
4135{
4136    struct mem_cgroup *mem, *parent;
4137    long error = -ENOMEM;
4138    int node;
4139
4140    mem = mem_cgroup_alloc();
4141    if (!mem)
4142        return ERR_PTR(error);
4143
4144    for_each_node_state(node, N_POSSIBLE)
4145        if (alloc_mem_cgroup_per_zone_info(mem, node))
4146            goto free_out;
4147
4148    /* root ? */
4149    if (cont->parent == NULL) {
4150        int cpu;
4151        enable_swap_cgroup();
4152        parent = NULL;
4153        root_mem_cgroup = mem;
4154        if (mem_cgroup_soft_limit_tree_init())
4155            goto free_out;
4156        for_each_possible_cpu(cpu) {
4157            struct memcg_stock_pcp *stock =
4158                        &per_cpu(memcg_stock, cpu);
4159            INIT_WORK(&stock->work, drain_local_stock);
4160        }
4161        hotcpu_notifier(memcg_stock_cpu_callback, 0);
4162    } else {
4163        parent = mem_cgroup_from_cont(cont->parent);
4164        mem->use_hierarchy = parent->use_hierarchy;
4165        mem->oom_kill_disable = parent->oom_kill_disable;
4166    }
4167
4168    if (parent && parent->use_hierarchy) {
4169        res_counter_init(&mem->res, &parent->res);
4170        res_counter_init(&mem->memsw, &parent->memsw);
4171        /*
4172         * We increment refcnt of the parent to ensure that we can
4173         * safely access it on res_counter_charge/uncharge.
4174         * This refcnt will be decremented when freeing this
4175         * mem_cgroup(see mem_cgroup_put).
4176         */
4177        mem_cgroup_get(parent);
4178    } else {
4179        res_counter_init(&mem->res, NULL);
4180        res_counter_init(&mem->memsw, NULL);
4181    }
4182    mem->last_scanned_child = 0;
4183    spin_lock_init(&mem->reclaim_param_lock);
4184    INIT_LIST_HEAD(&mem->oom_notify);
4185
4186    if (parent)
4187        mem->swappiness = get_swappiness(parent);
4188    atomic_set(&mem->refcnt, 1);
4189    mem->move_charge_at_immigrate = 0;
4190    mutex_init(&mem->thresholds_lock);
4191    return &mem->css;
4192free_out:
4193    __mem_cgroup_free(mem);
4194    root_mem_cgroup = NULL;
4195    return ERR_PTR(error);
4196}
4197
4198static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
4199                    struct cgroup *cont)
4200{
4201    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
4202
4203    return mem_cgroup_force_empty(mem, false);
4204}
4205
4206static void mem_cgroup_destroy(struct cgroup_subsys *ss,
4207                struct cgroup *cont)
4208{
4209    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
4210
4211    mem_cgroup_put(mem);
4212}
4213
4214static int mem_cgroup_populate(struct cgroup_subsys *ss,
4215                struct cgroup *cont)
4216{
4217    int ret;
4218
4219    ret = cgroup_add_files(cont, ss, mem_cgroup_files,
4220                ARRAY_SIZE(mem_cgroup_files));
4221
4222    if (!ret)
4223        ret = register_memsw_files(cont, ss);
4224    return ret;
4225}
4226
4227#ifdef CONFIG_MMU
4228/* Handlers for move charge at task migration. */
4229#define PRECHARGE_COUNT_AT_ONCE 256
4230static int mem_cgroup_do_precharge(unsigned long count)
4231{
4232    int ret = 0;
4233    int batch_count = PRECHARGE_COUNT_AT_ONCE;
4234    struct mem_cgroup *mem = mc.to;
4235
4236    if (mem_cgroup_is_root(mem)) {
4237        mc.precharge += count;
4238        /* we don't need css_get for root */
4239        return ret;
4240    }
4241    /* try to charge at once */
4242    if (count > 1) {
4243        struct res_counter *dummy;
4244        /*
4245         * "mem" cannot be under rmdir() because we've already checked
4246         * by cgroup_lock_live_cgroup() that it is not removed and we
4247         * are still under the same cgroup_mutex. So we can postpone
4248         * css_get().
4249         */
4250        if (res_counter_charge(&mem->res, PAGE_SIZE * count, &dummy))
4251            goto one_by_one;
4252        if (do_swap_account && res_counter_charge(&mem->memsw,
4253                        PAGE_SIZE * count, &dummy)) {
4254            res_counter_uncharge(&mem->res, PAGE_SIZE * count);
4255            goto one_by_one;
4256        }
4257        mc.precharge += count;
4258        return ret;
4259    }
4260one_by_one:
4261    /* fall back to one by one charge */
4262    while (count--) {
4263        if (signal_pending(current)) {
4264            ret = -EINTR;
4265            break;
4266        }
4267        if (!batch_count--) {
4268            batch_count = PRECHARGE_COUNT_AT_ONCE;
4269            cond_resched();
4270        }
4271        ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
4272        if (ret || !mem)
4273            /* mem_cgroup_clear_mc() will do uncharge later */
4274            return -ENOMEM;
4275        mc.precharge++;
4276    }
4277    return ret;
4278}
4279
4280/**
4281 * is_target_pte_for_mc - check a pte whether it is valid for move charge
4282 * @vma: the vma the pte to be checked belongs
4283 * @addr: the address corresponding to the pte to be checked
4284 * @ptent: the pte to be checked
4285 * @target: the pointer the target page or swap ent will be stored(can be NULL)
4286 *
4287 * Returns
4288 * 0(MC_TARGET_NONE): if the pte is not a target for move charge.
4289 * 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
4290 * move charge. if @target is not NULL, the page is stored in target->page
4291 * with extra refcnt got(Callers should handle it).
4292 * 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
4293 * target for charge migration. if @target is not NULL, the entry is stored
4294 * in target->ent.
4295 *
4296 * Called with pte lock held.
4297 */
4298union mc_target {
4299    struct page *page;
4300    swp_entry_t ent;
4301};
4302
4303enum mc_target_type {
4304    MC_TARGET_NONE, /* not used */
4305    MC_TARGET_PAGE,
4306    MC_TARGET_SWAP,
4307};
4308
4309static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
4310                        unsigned long addr, pte_t ptent)
4311{
4312    struct page *page = vm_normal_page(vma, addr, ptent);
4313
4314    if (!page || !page_mapped(page))
4315        return NULL;
4316    if (PageAnon(page)) {
4317        /* we don't move shared anon */
4318        if (!move_anon() || page_mapcount(page) > 2)
4319            return NULL;
4320    } else if (!move_file())
4321        /* we ignore mapcount for file pages */
4322        return NULL;
4323    if (!get_page_unless_zero(page))
4324        return NULL;
4325
4326    return page;
4327}
4328
4329static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
4330            unsigned long addr, pte_t ptent, swp_entry_t *entry)
4331{
4332    int usage_count;
4333    struct page *page = NULL;
4334    swp_entry_t ent = pte_to_swp_entry(ptent);
4335
4336    if (!move_anon() || non_swap_entry(ent))
4337        return NULL;
4338    usage_count = mem_cgroup_count_swap_user(ent, &page);
4339    if (usage_count > 1) { /* we don't move shared anon */
4340        if (page)
4341            put_page(page);
4342        return NULL;
4343    }
4344    if (do_swap_account)
4345        entry->val = ent.val;
4346
4347    return page;
4348}
4349
4350static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
4351            unsigned long addr, pte_t ptent, swp_entry_t *entry)
4352{
4353    struct page *page = NULL;
4354    struct inode *inode;
4355    struct address_space *mapping;
4356    pgoff_t pgoff;
4357
4358    if (!vma->vm_file) /* anonymous vma */
4359        return NULL;
4360    if (!move_file())
4361        return NULL;
4362
4363    inode = vma->vm_file->f_path.dentry->d_inode;
4364    mapping = vma->vm_file->f_mapping;
4365    if (pte_none(ptent))
4366        pgoff = linear_page_index(vma, addr);
4367    else /* pte_file(ptent) is true */
4368        pgoff = pte_to_pgoff(ptent);
4369
4370    /* page is moved even if it's not RSS of this task(page-faulted). */
4371    if (!mapping_cap_swap_backed(mapping)) { /* normal file */
4372        page = find_get_page(mapping, pgoff);
4373    } else { /* shmem/tmpfs file. we should take account of swap too. */
4374        swp_entry_t ent;
4375        mem_cgroup_get_shmem_target(inode, pgoff, &page, &ent);
4376        if (do_swap_account)
4377            entry->val = ent.val;
4378    }
4379
4380    return page;
4381}
4382
4383static int is_target_pte_for_mc(struct vm_area_struct *vma,
4384        unsigned long addr, pte_t ptent, union mc_target *target)
4385{
4386    struct page *page = NULL;
4387    struct page_cgroup *pc;
4388    int ret = 0;
4389    swp_entry_t ent = { .val = 0 };
4390
4391    if (pte_present(ptent))
4392        page = mc_handle_present_pte(vma, addr, ptent);
4393    else if (is_swap_pte(ptent))
4394        page = mc_handle_swap_pte(vma, addr, ptent, &ent);
4395    else if (pte_none(ptent) || pte_file(ptent))
4396        page = mc_handle_file_pte(vma, addr, ptent, &ent);
4397
4398    if (!page && !ent.val)
4399        return 0;
4400    if (page) {
4401        pc = lookup_page_cgroup(page);
4402        /*
4403         * Do only loose check w/o page_cgroup lock.
4404         * mem_cgroup_move_account() checks the pc is valid or not under
4405         * the lock.
4406         */
4407        if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
4408            ret = MC_TARGET_PAGE;
4409            if (target)
4410                target->page = page;
4411        }
4412        if (!ret || !target)
4413            put_page(page);
4414    }
4415    /* There is a swap entry and a page doesn't exist or isn't charged */
4416    if (ent.val && !ret &&
4417            css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
4418        ret = MC_TARGET_SWAP;
4419        if (target)
4420            target->ent = ent;
4421    }
4422    return ret;
4423}
4424
4425static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
4426                    unsigned long addr, unsigned long end,
4427                    struct mm_walk *walk)
4428{
4429    struct vm_area_struct *vma = walk->private;
4430    pte_t *pte;
4431    spinlock_t *ptl;
4432
4433    pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4434    for (; addr != end; pte++, addr += PAGE_SIZE)
4435        if (is_target_pte_for_mc(vma, addr, *pte, NULL))
4436            mc.precharge++; /* increment precharge temporarily */
4437    pte_unmap_unlock(pte - 1, ptl);
4438    cond_resched();
4439
4440    return 0;
4441}
4442
4443static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
4444{
4445    unsigned long precharge;
4446    struct vm_area_struct *vma;
4447
4448    down_read(&mm->mmap_sem);
4449    for (vma = mm->mmap; vma; vma = vma->vm_next) {
4450        struct mm_walk mem_cgroup_count_precharge_walk = {
4451            .pmd_entry = mem_cgroup_count_precharge_pte_range,
4452            .mm = mm,
4453            .private = vma,
4454        };
4455        if (is_vm_hugetlb_page(vma))
4456            continue;
4457        walk_page_range(vma->vm_start, vma->vm_end,
4458                    &mem_cgroup_count_precharge_walk);
4459    }
4460    up_read(&mm->mmap_sem);
4461
4462    precharge = mc.precharge;
4463    mc.precharge = 0;
4464
4465    return precharge;
4466}
4467
4468static int mem_cgroup_precharge_mc(struct mm_struct *mm)
4469{
4470    return mem_cgroup_do_precharge(mem_cgroup_count_precharge(mm));
4471}
4472
4473static void mem_cgroup_clear_mc(void)
4474{
4475    struct mem_cgroup *from = mc.from;
4476    struct mem_cgroup *to = mc.to;
4477
4478    /* we must uncharge all the leftover precharges from mc.to */
4479    if (mc.precharge) {
4480        __mem_cgroup_cancel_charge(mc.to, mc.precharge);
4481        mc.precharge = 0;
4482    }
4483    /*
4484     * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
4485     * we must uncharge here.
4486     */
4487    if (mc.moved_charge) {
4488        __mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
4489        mc.moved_charge = 0;
4490    }
4491    /* we must fixup refcnts and charges */
4492    if (mc.moved_swap) {
4493        /* uncharge swap account from the old cgroup */
4494        if (!mem_cgroup_is_root(mc.from))
4495            res_counter_uncharge(&mc.from->memsw,
4496                        PAGE_SIZE * mc.moved_swap);
4497        __mem_cgroup_put(mc.from, mc.moved_swap);
4498
4499        if (!mem_cgroup_is_root(mc.to)) {
4500            /*
4501             * we charged both to->res and to->memsw, so we should
4502             * uncharge to->res.
4503             */
4504            res_counter_uncharge(&mc.to->res,
4505                        PAGE_SIZE * mc.moved_swap);
4506        }
4507        /* we've already done mem_cgroup_get(mc.to) */
4508
4509        mc.moved_swap = 0;
4510    }
4511    spin_lock(&mc.lock);
4512    mc.from = NULL;
4513    mc.to = NULL;
4514    mc.moving_task = NULL;
4515    spin_unlock(&mc.lock);
4516    memcg_oom_recover(from);
4517    memcg_oom_recover(to);
4518    wake_up_all(&mc.waitq);
4519}
4520
4521static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4522                struct cgroup *cgroup,
4523                struct task_struct *p,
4524                bool threadgroup)
4525{
4526    int ret = 0;
4527    struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup);
4528
4529    if (mem->move_charge_at_immigrate) {
4530        struct mm_struct *mm;
4531        struct mem_cgroup *from = mem_cgroup_from_task(p);
4532
4533        VM_BUG_ON(from == mem);
4534
4535        mm = get_task_mm(p);
4536        if (!mm)
4537            return 0;
4538        /* We move charges only when we move a owner of the mm */
4539        if (mm->owner == p) {
4540            VM_BUG_ON(mc.from);
4541            VM_BUG_ON(mc.to);
4542            VM_BUG_ON(mc.precharge);
4543            VM_BUG_ON(mc.moved_charge);
4544            VM_BUG_ON(mc.moved_swap);
4545            VM_BUG_ON(mc.moving_task);
4546            spin_lock(&mc.lock);
4547            mc.from = from;
4548            mc.to = mem;
4549            mc.precharge = 0;
4550            mc.moved_charge = 0;
4551            mc.moved_swap = 0;
4552            mc.moving_task = current;
4553            spin_unlock(&mc.lock);
4554
4555            ret = mem_cgroup_precharge_mc(mm);
4556            if (ret)
4557                mem_cgroup_clear_mc();
4558        }
4559        mmput(mm);
4560    }
4561    return ret;
4562}
4563
4564static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4565                struct cgroup *cgroup,
4566                struct task_struct *p,
4567                bool threadgroup)
4568{
4569    mem_cgroup_clear_mc();
4570}
4571
4572static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
4573                unsigned long addr, unsigned long end,
4574                struct mm_walk *walk)
4575{
4576    int ret = 0;
4577    struct vm_area_struct *vma = walk->private;
4578    pte_t *pte;
4579    spinlock_t *ptl;
4580
4581retry:
4582    pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4583    for (; addr != end; addr += PAGE_SIZE) {
4584        pte_t ptent = *(pte++);
4585        union mc_target target;
4586        int type;
4587        struct page *page;
4588        struct page_cgroup *pc;
4589        swp_entry_t ent;
4590
4591        if (!mc.precharge)
4592            break;
4593
4594        type = is_target_pte_for_mc(vma, addr, ptent, &target);
4595        switch (type) {
4596        case MC_TARGET_PAGE:
4597            page = target.page;
4598            if (isolate_lru_page(page))
4599                goto put;
4600            pc = lookup_page_cgroup(page);
4601            if (!mem_cgroup_move_account(pc,
4602                        mc.from, mc.to, false)) {
4603                mc.precharge--;
4604                /* we uncharge from mc.from later. */
4605                mc.moved_charge++;
4606            }
4607            putback_lru_page(page);
4608put: /* is_target_pte_for_mc() gets the page */
4609            put_page(page);
4610            break;
4611        case MC_TARGET_SWAP:
4612            ent = target.ent;
4613            if (!mem_cgroup_move_swap_account(ent,
4614                        mc.from, mc.to, false)) {
4615                mc.precharge--;
4616                /* we fixup refcnts and charges later. */
4617                mc.moved_swap++;
4618            }
4619            break;
4620        default:
4621            break;
4622        }
4623    }
4624    pte_unmap_unlock(pte - 1, ptl);
4625    cond_resched();
4626
4627    if (addr != end) {
4628        /*
4629         * We have consumed all precharges we got in can_attach().
4630         * We try charge one by one, but don't do any additional
4631         * charges to mc.to if we have failed in charge once in attach()
4632         * phase.
4633         */
4634        ret = mem_cgroup_do_precharge(1);
4635        if (!ret)
4636            goto retry;
4637    }
4638
4639    return ret;
4640}
4641
4642static void mem_cgroup_move_charge(struct mm_struct *mm)
4643{
4644    struct vm_area_struct *vma;
4645
4646    lru_add_drain_all();
4647    down_read(&mm->mmap_sem);
4648    for (vma = mm->mmap; vma; vma = vma->vm_next) {
4649        int ret;
4650        struct mm_walk mem_cgroup_move_charge_walk = {
4651            .pmd_entry = mem_cgroup_move_charge_pte_range,
4652            .mm = mm,
4653            .private = vma,
4654        };
4655        if (is_vm_hugetlb_page(vma))
4656            continue;
4657        ret = walk_page_range(vma->vm_start, vma->vm_end,
4658                        &mem_cgroup_move_charge_walk);
4659        if (ret)
4660            /*
4661             * means we have consumed all precharges and failed in
4662             * doing additional charge. Just abandon here.
4663             */
4664            break;
4665    }
4666    up_read(&mm->mmap_sem);
4667}
4668
4669static void mem_cgroup_move_task(struct cgroup_subsys *ss,
4670                struct cgroup *cont,
4671                struct cgroup *old_cont,
4672                struct task_struct *p,
4673                bool threadgroup)
4674{
4675    struct mm_struct *mm;
4676
4677    if (!mc.to)
4678        /* no need to move charge */
4679        return;
4680
4681    mm = get_task_mm(p);
4682    if (mm) {
4683        mem_cgroup_move_charge(mm);
4684        mmput(mm);
4685    }
4686    mem_cgroup_clear_mc();
4687}
4688#else /* !CONFIG_MMU */
4689static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4690                struct cgroup *cgroup,
4691                struct task_struct *p,
4692                bool threadgroup)
4693{
4694    return 0;
4695}
4696static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4697                struct cgroup *cgroup,
4698                struct task_struct *p,
4699                bool threadgroup)
4700{
4701}
4702static void mem_cgroup_move_task(struct cgroup_subsys *ss,
4703                struct cgroup *cont,
4704                struct cgroup *old_cont,
4705                struct task_struct *p,
4706                bool threadgroup)
4707{
4708}
4709#endif
4710
4711struct cgroup_subsys mem_cgroup_subsys = {
4712    .name = "memory",
4713    .subsys_id = mem_cgroup_subsys_id,
4714    .create = mem_cgroup_create,
4715    .pre_destroy = mem_cgroup_pre_destroy,
4716    .destroy = mem_cgroup_destroy,
4717    .populate = mem_cgroup_populate,
4718    .can_attach = mem_cgroup_can_attach,
4719    .cancel_attach = mem_cgroup_cancel_attach,
4720    .attach = mem_cgroup_move_task,
4721    .early_init = 0,
4722    .use_id = 1,
4723};
4724
4725#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4726
4727static int __init disable_swap_account(char *s)
4728{
4729    really_do_swap_account = 0;
4730    return 1;
4731}
4732__setup("noswapaccount", disable_swap_account);
4733#endif
4734

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