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 "internal.h"
51
52#include <asm/uaccess.h>
53
54struct cgroup_subsys mem_cgroup_subsys __read_mostly;
55#define MEM_CGROUP_RECLAIM_RETRIES 5
56struct mem_cgroup *root_mem_cgroup __read_mostly;
57
58#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
59/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
60int do_swap_account __read_mostly;
61static int really_do_swap_account __initdata = 1; /* for remember boot option*/
62#else
63#define do_swap_account (0)
64#endif
65
66/*
67 * Per memcg event counter is incremented at every pagein/pageout. This counter
68 * is used for trigger some periodic events. This is straightforward and better
69 * than using jiffies etc. to handle periodic memcg event.
70 *
71 * These values will be used as !((event) & ((1 <<(thresh)) - 1))
72 */
73#define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
74#define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
75
76/*
77 * Statistics for memory cgroup.
78 */
79enum mem_cgroup_stat_index {
80    /*
81     * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
82     */
83    MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */
84    MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */
85    MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */
86    MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */
87    MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */
88    MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
89    MEM_CGROUP_EVENTS, /* incremented at every pagein/pageout */
90
91    MEM_CGROUP_STAT_NSTATS,
92};
93
94struct mem_cgroup_stat_cpu {
95    s64 count[MEM_CGROUP_STAT_NSTATS];
96};
97
98/*
99 * per-zone information in memory controller.
100 */
101struct mem_cgroup_per_zone {
102    /*
103     * spin_lock to protect the per cgroup LRU
104     */
105    struct list_head lists[NR_LRU_LISTS];
106    unsigned long count[NR_LRU_LISTS];
107
108    struct zone_reclaim_stat reclaim_stat;
109    struct rb_node tree_node; /* RB tree node */
110    unsigned long long usage_in_excess;/* Set to the value by which */
111                        /* the soft limit is exceeded*/
112    bool on_tree;
113    struct mem_cgroup *mem; /* Back pointer, we cannot */
114                        /* use container_of */
115};
116/* Macro for accessing counter */
117#define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)])
118
119struct mem_cgroup_per_node {
120    struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
121};
122
123struct mem_cgroup_lru_info {
124    struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
125};
126
127/*
128 * Cgroups above their limits are maintained in a RB-Tree, independent of
129 * their hierarchy representation
130 */
131
132struct mem_cgroup_tree_per_zone {
133    struct rb_root rb_root;
134    spinlock_t lock;
135};
136
137struct mem_cgroup_tree_per_node {
138    struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
139};
140
141struct mem_cgroup_tree {
142    struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
143};
144
145static struct mem_cgroup_tree soft_limit_tree __read_mostly;
146
147struct mem_cgroup_threshold {
148    struct eventfd_ctx *eventfd;
149    u64 threshold;
150};
151
152struct mem_cgroup_threshold_ary {
153    /* An array index points to threshold just below usage. */
154    atomic_t current_threshold;
155    /* Size of entries[] */
156    unsigned int size;
157    /* Array of thresholds */
158    struct mem_cgroup_threshold entries[0];
159};
160
161static void mem_cgroup_threshold(struct mem_cgroup *mem);
162
163/*
164 * The memory controller data structure. The memory controller controls both
165 * page cache and RSS per cgroup. We would eventually like to provide
166 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
167 * to help the administrator determine what knobs to tune.
168 *
169 * TODO: Add a water mark for the memory controller. Reclaim will begin when
170 * we hit the water mark. May be even add a low water mark, such that
171 * no reclaim occurs from a cgroup at it's low water mark, this is
172 * a feature that will be implemented much later in the future.
173 */
174struct mem_cgroup {
175    struct cgroup_subsys_state css;
176    /*
177     * the counter to account for memory usage
178     */
179    struct res_counter res;
180    /*
181     * the counter to account for mem+swap usage.
182     */
183    struct res_counter memsw;
184    /*
185     * Per cgroup active and inactive list, similar to the
186     * per zone LRU lists.
187     */
188    struct mem_cgroup_lru_info info;
189
190    /*
191      protect against reclaim related member.
192    */
193    spinlock_t reclaim_param_lock;
194
195    int prev_priority; /* for recording reclaim priority */
196
197    /*
198     * While reclaiming in a hierarchy, we cache the last child we
199     * reclaimed from.
200     */
201    int last_scanned_child;
202    /*
203     * Should the accounting and control be hierarchical, per subtree?
204     */
205    bool use_hierarchy;
206    atomic_t oom_lock;
207    atomic_t refcnt;
208
209    unsigned int swappiness;
210
211    /* set when res.limit == memsw.limit */
212    bool memsw_is_minimum;
213
214    /* protect arrays of thresholds */
215    struct mutex thresholds_lock;
216
217    /* thresholds for memory usage. RCU-protected */
218    struct mem_cgroup_threshold_ary *thresholds;
219
220    /* thresholds for mem+swap usage. RCU-protected */
221    struct mem_cgroup_threshold_ary *memsw_thresholds;
222
223    /*
224     * Should we move charges of a task when a task is moved into this
225     * mem_cgroup ? And what type of charges should we move ?
226     */
227    unsigned long move_charge_at_immigrate;
228
229    /*
230     * percpu counter.
231     */
232    struct mem_cgroup_stat_cpu *stat;
233};
234
235/* Stuffs for move charges at task migration. */
236/*
237 * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
238 * left-shifted bitmap of these types.
239 */
240enum move_type {
241    MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
242    NR_MOVE_TYPE,
243};
244
245/* "mc" and its members are protected by cgroup_mutex */
246static struct move_charge_struct {
247    struct mem_cgroup *from;
248    struct mem_cgroup *to;
249    unsigned long precharge;
250    unsigned long moved_charge;
251    unsigned long moved_swap;
252    struct task_struct *moving_task; /* a task moving charges */
253    wait_queue_head_t waitq; /* a waitq for other context */
254} mc = {
255    .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
256};
257
258/*
259 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
260 * limit reclaim to prevent infinite loops, if they ever occur.
261 */
262#define MEM_CGROUP_MAX_RECLAIM_LOOPS (100)
263#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2)
264
265enum charge_type {
266    MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
267    MEM_CGROUP_CHARGE_TYPE_MAPPED,
268    MEM_CGROUP_CHARGE_TYPE_SHMEM, /* used by page migration of shmem */
269    MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */
270    MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
271    MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */
272    NR_CHARGE_TYPE,
273};
274
275/* only for here (for easy reading.) */
276#define PCGF_CACHE (1UL << PCG_CACHE)
277#define PCGF_USED (1UL << PCG_USED)
278#define PCGF_LOCK (1UL << PCG_LOCK)
279/* Not used, but added here for completeness */
280#define PCGF_ACCT (1UL << PCG_ACCT)
281
282/* for encoding cft->private value on file */
283#define _MEM (0)
284#define _MEMSWAP (1)
285#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
286#define MEMFILE_TYPE(val) (((val) >> 16) & 0xffff)
287#define MEMFILE_ATTR(val) ((val) & 0xffff)
288
289/*
290 * Reclaim flags for mem_cgroup_hierarchical_reclaim
291 */
292#define MEM_CGROUP_RECLAIM_NOSWAP_BIT 0x0
293#define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
294#define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1
295#define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
296#define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2
297#define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
298
299static void mem_cgroup_get(struct mem_cgroup *mem);
300static void mem_cgroup_put(struct mem_cgroup *mem);
301static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
302static void drain_all_stock_async(void);
303
304static struct mem_cgroup_per_zone *
305mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
306{
307    return &mem->info.nodeinfo[nid]->zoneinfo[zid];
308}
309
310struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
311{
312    return &mem->css;
313}
314
315static struct mem_cgroup_per_zone *
316page_cgroup_zoneinfo(struct page_cgroup *pc)
317{
318    struct mem_cgroup *mem = pc->mem_cgroup;
319    int nid = page_cgroup_nid(pc);
320    int zid = page_cgroup_zid(pc);
321
322    if (!mem)
323        return NULL;
324
325    return mem_cgroup_zoneinfo(mem, nid, zid);
326}
327
328static struct mem_cgroup_tree_per_zone *
329soft_limit_tree_node_zone(int nid, int zid)
330{
331    return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
332}
333
334static struct mem_cgroup_tree_per_zone *
335soft_limit_tree_from_page(struct page *page)
336{
337    int nid = page_to_nid(page);
338    int zid = page_zonenum(page);
339
340    return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
341}
342
343static void
344__mem_cgroup_insert_exceeded(struct mem_cgroup *mem,
345                struct mem_cgroup_per_zone *mz,
346                struct mem_cgroup_tree_per_zone *mctz,
347                unsigned long long new_usage_in_excess)
348{
349    struct rb_node **p = &mctz->rb_root.rb_node;
350    struct rb_node *parent = NULL;
351    struct mem_cgroup_per_zone *mz_node;
352
353    if (mz->on_tree)
354        return;
355
356    mz->usage_in_excess = new_usage_in_excess;
357    if (!mz->usage_in_excess)
358        return;
359    while (*p) {
360        parent = *p;
361        mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
362                    tree_node);
363        if (mz->usage_in_excess < mz_node->usage_in_excess)
364            p = &(*p)->rb_left;
365        /*
366         * We can't avoid mem cgroups that are over their soft
367         * limit by the same amount
368         */
369        else if (mz->usage_in_excess >= mz_node->usage_in_excess)
370            p = &(*p)->rb_right;
371    }
372    rb_link_node(&mz->tree_node, parent, p);
373    rb_insert_color(&mz->tree_node, &mctz->rb_root);
374    mz->on_tree = true;
375}
376
377static void
378__mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
379                struct mem_cgroup_per_zone *mz,
380                struct mem_cgroup_tree_per_zone *mctz)
381{
382    if (!mz->on_tree)
383        return;
384    rb_erase(&mz->tree_node, &mctz->rb_root);
385    mz->on_tree = false;
386}
387
388static void
389mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
390                struct mem_cgroup_per_zone *mz,
391                struct mem_cgroup_tree_per_zone *mctz)
392{
393    spin_lock(&mctz->lock);
394    __mem_cgroup_remove_exceeded(mem, mz, mctz);
395    spin_unlock(&mctz->lock);
396}
397
398
399static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
400{
401    unsigned long long excess;
402    struct mem_cgroup_per_zone *mz;
403    struct mem_cgroup_tree_per_zone *mctz;
404    int nid = page_to_nid(page);
405    int zid = page_zonenum(page);
406    mctz = soft_limit_tree_from_page(page);
407
408    /*
409     * Necessary to update all ancestors when hierarchy is used.
410     * because their event counter is not touched.
411     */
412    for (; mem; mem = parent_mem_cgroup(mem)) {
413        mz = mem_cgroup_zoneinfo(mem, nid, zid);
414        excess = res_counter_soft_limit_excess(&mem->res);
415        /*
416         * We have to update the tree if mz is on RB-tree or
417         * mem is over its softlimit.
418         */
419        if (excess || mz->on_tree) {
420            spin_lock(&mctz->lock);
421            /* if on-tree, remove it */
422            if (mz->on_tree)
423                __mem_cgroup_remove_exceeded(mem, mz, mctz);
424            /*
425             * Insert again. mz->usage_in_excess will be updated.
426             * If excess is 0, no tree ops.
427             */
428            __mem_cgroup_insert_exceeded(mem, mz, mctz, excess);
429            spin_unlock(&mctz->lock);
430        }
431    }
432}
433
434static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
435{
436    int node, zone;
437    struct mem_cgroup_per_zone *mz;
438    struct mem_cgroup_tree_per_zone *mctz;
439
440    for_each_node_state(node, N_POSSIBLE) {
441        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
442            mz = mem_cgroup_zoneinfo(mem, node, zone);
443            mctz = soft_limit_tree_node_zone(node, zone);
444            mem_cgroup_remove_exceeded(mem, mz, mctz);
445        }
446    }
447}
448
449static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
450{
451    return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
452}
453
454static struct mem_cgroup_per_zone *
455__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
456{
457    struct rb_node *rightmost = NULL;
458    struct mem_cgroup_per_zone *mz;
459
460retry:
461    mz = NULL;
462    rightmost = rb_last(&mctz->rb_root);
463    if (!rightmost)
464        goto done; /* Nothing to reclaim from */
465
466    mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
467    /*
468     * Remove the node now but someone else can add it back,
469     * we will to add it back at the end of reclaim to its correct
470     * position in the tree.
471     */
472    __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
473    if (!res_counter_soft_limit_excess(&mz->mem->res) ||
474        !css_tryget(&mz->mem->css))
475        goto retry;
476done:
477    return mz;
478}
479
480static struct mem_cgroup_per_zone *
481mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
482{
483    struct mem_cgroup_per_zone *mz;
484
485    spin_lock(&mctz->lock);
486    mz = __mem_cgroup_largest_soft_limit_node(mctz);
487    spin_unlock(&mctz->lock);
488    return mz;
489}
490
491static s64 mem_cgroup_read_stat(struct mem_cgroup *mem,
492        enum mem_cgroup_stat_index idx)
493{
494    int cpu;
495    s64 val = 0;
496
497    for_each_possible_cpu(cpu)
498        val += per_cpu(mem->stat->count[idx], cpu);
499    return val;
500}
501
502static s64 mem_cgroup_local_usage(struct mem_cgroup *mem)
503{
504    s64 ret;
505
506    ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
507    ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
508    return ret;
509}
510
511static void mem_cgroup_swap_statistics(struct mem_cgroup *mem,
512                     bool charge)
513{
514    int val = (charge) ? 1 : -1;
515    this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
516}
517
518static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
519                     struct page_cgroup *pc,
520                     bool charge)
521{
522    int val = (charge) ? 1 : -1;
523
524    preempt_disable();
525
526    if (PageCgroupCache(pc))
527        __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_CACHE], val);
528    else
529        __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_RSS], val);
530
531    if (charge)
532        __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
533    else
534        __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
535    __this_cpu_inc(mem->stat->count[MEM_CGROUP_EVENTS]);
536
537    preempt_enable();
538}
539
540static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
541                    enum lru_list idx)
542{
543    int nid, zid;
544    struct mem_cgroup_per_zone *mz;
545    u64 total = 0;
546
547    for_each_online_node(nid)
548        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
549            mz = mem_cgroup_zoneinfo(mem, nid, zid);
550            total += MEM_CGROUP_ZSTAT(mz, idx);
551        }
552    return total;
553}
554
555static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
556{
557    s64 val;
558
559    val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
560
561    return !(val & ((1 << event_mask_shift) - 1));
562}
563
564/*
565 * Check events in order.
566 *
567 */
568static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
569{
570    /* threshold event is triggered in finer grain than soft limit */
571    if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
572        mem_cgroup_threshold(mem);
573        if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
574            mem_cgroup_update_tree(mem, page);
575    }
576}
577
578static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
579{
580    return container_of(cgroup_subsys_state(cont,
581                mem_cgroup_subsys_id), struct mem_cgroup,
582                css);
583}
584
585struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
586{
587    /*
588     * mm_update_next_owner() may clear mm->owner to NULL
589     * if it races with swapoff, page migration, etc.
590     * So this can be called with p == NULL.
591     */
592    if (unlikely(!p))
593        return NULL;
594
595    return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
596                struct mem_cgroup, css);
597}
598
599static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
600{
601    struct mem_cgroup *mem = NULL;
602
603    if (!mm)
604        return NULL;
605    /*
606     * Because we have no locks, mm->owner's may be being moved to other
607     * cgroup. We use css_tryget() here even if this looks
608     * pessimistic (rather than adding locks here).
609     */
610    rcu_read_lock();
611    do {
612        mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
613        if (unlikely(!mem))
614            break;
615    } while (!css_tryget(&mem->css));
616    rcu_read_unlock();
617    return mem;
618}
619
620/*
621 * Call callback function against all cgroup under hierarchy tree.
622 */
623static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
624              int (*func)(struct mem_cgroup *, void *))
625{
626    int found, ret, nextid;
627    struct cgroup_subsys_state *css;
628    struct mem_cgroup *mem;
629
630    if (!root->use_hierarchy)
631        return (*func)(root, data);
632
633    nextid = 1;
634    do {
635        ret = 0;
636        mem = NULL;
637
638        rcu_read_lock();
639        css = css_get_next(&mem_cgroup_subsys, nextid, &root->css,
640                   &found);
641        if (css && css_tryget(css))
642            mem = container_of(css, struct mem_cgroup, css);
643        rcu_read_unlock();
644
645        if (mem) {
646            ret = (*func)(mem, data);
647            css_put(&mem->css);
648        }
649        nextid = found + 1;
650    } while (!ret && css);
651
652    return ret;
653}
654
655static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
656{
657    return (mem == root_mem_cgroup);
658}
659
660/*
661 * Following LRU functions are allowed to be used without PCG_LOCK.
662 * Operations are called by routine of global LRU independently from memcg.
663 * What we have to take care of here is validness of pc->mem_cgroup.
664 *
665 * Changes to pc->mem_cgroup happens when
666 * 1. charge
667 * 2. moving account
668 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
669 * It is added to LRU before charge.
670 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
671 * When moving account, the page is not on LRU. It's isolated.
672 */
673
674void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
675{
676    struct page_cgroup *pc;
677    struct mem_cgroup_per_zone *mz;
678
679    if (mem_cgroup_disabled())
680        return;
681    pc = lookup_page_cgroup(page);
682    /* can happen while we handle swapcache. */
683    if (!TestClearPageCgroupAcctLRU(pc))
684        return;
685    VM_BUG_ON(!pc->mem_cgroup);
686    /*
687     * We don't check PCG_USED bit. It's cleared when the "page" is finally
688     * removed from global LRU.
689     */
690    mz = page_cgroup_zoneinfo(pc);
691    MEM_CGROUP_ZSTAT(mz, lru) -= 1;
692    if (mem_cgroup_is_root(pc->mem_cgroup))
693        return;
694    VM_BUG_ON(list_empty(&pc->lru));
695    list_del_init(&pc->lru);
696    return;
697}
698
699void mem_cgroup_del_lru(struct page *page)
700{
701    mem_cgroup_del_lru_list(page, page_lru(page));
702}
703
704void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
705{
706    struct mem_cgroup_per_zone *mz;
707    struct page_cgroup *pc;
708
709    if (mem_cgroup_disabled())
710        return;
711
712    pc = lookup_page_cgroup(page);
713    /*
714     * Used bit is set without atomic ops but after smp_wmb().
715     * For making pc->mem_cgroup visible, insert smp_rmb() here.
716     */
717    smp_rmb();
718    /* unused or root page is not rotated. */
719    if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
720        return;
721    mz = page_cgroup_zoneinfo(pc);
722    list_move(&pc->lru, &mz->lists[lru]);
723}
724
725void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
726{
727    struct page_cgroup *pc;
728    struct mem_cgroup_per_zone *mz;
729
730    if (mem_cgroup_disabled())
731        return;
732    pc = lookup_page_cgroup(page);
733    VM_BUG_ON(PageCgroupAcctLRU(pc));
734    /*
735     * Used bit is set without atomic ops but after smp_wmb().
736     * For making pc->mem_cgroup visible, insert smp_rmb() here.
737     */
738    smp_rmb();
739    if (!PageCgroupUsed(pc))
740        return;
741
742    mz = page_cgroup_zoneinfo(pc);
743    MEM_CGROUP_ZSTAT(mz, lru) += 1;
744    SetPageCgroupAcctLRU(pc);
745    if (mem_cgroup_is_root(pc->mem_cgroup))
746        return;
747    list_add(&pc->lru, &mz->lists[lru]);
748}
749
750/*
751 * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
752 * lru because the page may.be reused after it's fully uncharged (because of
753 * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
754 * it again. This function is only used to charge SwapCache. It's done under
755 * lock_page and expected that zone->lru_lock is never held.
756 */
757static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
758{
759    unsigned long flags;
760    struct zone *zone = page_zone(page);
761    struct page_cgroup *pc = lookup_page_cgroup(page);
762
763    spin_lock_irqsave(&zone->lru_lock, flags);
764    /*
765     * Forget old LRU when this page_cgroup is *not* used. This Used bit
766     * is guarded by lock_page() because the page is SwapCache.
767     */
768    if (!PageCgroupUsed(pc))
769        mem_cgroup_del_lru_list(page, page_lru(page));
770    spin_unlock_irqrestore(&zone->lru_lock, flags);
771}
772
773static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
774{
775    unsigned long flags;
776    struct zone *zone = page_zone(page);
777    struct page_cgroup *pc = lookup_page_cgroup(page);
778
779    spin_lock_irqsave(&zone->lru_lock, flags);
780    /* link when the page is linked to LRU but page_cgroup isn't */
781    if (PageLRU(page) && !PageCgroupAcctLRU(pc))
782        mem_cgroup_add_lru_list(page, page_lru(page));
783    spin_unlock_irqrestore(&zone->lru_lock, flags);
784}
785
786
787void mem_cgroup_move_lists(struct page *page,
788               enum lru_list from, enum lru_list to)
789{
790    if (mem_cgroup_disabled())
791        return;
792    mem_cgroup_del_lru_list(page, from);
793    mem_cgroup_add_lru_list(page, to);
794}
795
796int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
797{
798    int ret;
799    struct mem_cgroup *curr = NULL;
800
801    task_lock(task);
802    rcu_read_lock();
803    curr = try_get_mem_cgroup_from_mm(task->mm);
804    rcu_read_unlock();
805    task_unlock(task);
806    if (!curr)
807        return 0;
808    /*
809     * We should check use_hierarchy of "mem" not "curr". Because checking
810     * use_hierarchy of "curr" here make this function true if hierarchy is
811     * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
812     * hierarchy(even if use_hierarchy is disabled in "mem").
813     */
814    if (mem->use_hierarchy)
815        ret = css_is_ancestor(&curr->css, &mem->css);
816    else
817        ret = (curr == mem);
818    css_put(&curr->css);
819    return ret;
820}
821
822/*
823 * prev_priority control...this will be used in memory reclaim path.
824 */
825int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
826{
827    int prev_priority;
828
829    spin_lock(&mem->reclaim_param_lock);
830    prev_priority = mem->prev_priority;
831    spin_unlock(&mem->reclaim_param_lock);
832
833    return prev_priority;
834}
835
836void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority)
837{
838    spin_lock(&mem->reclaim_param_lock);
839    if (priority < mem->prev_priority)
840        mem->prev_priority = priority;
841    spin_unlock(&mem->reclaim_param_lock);
842}
843
844void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
845{
846    spin_lock(&mem->reclaim_param_lock);
847    mem->prev_priority = priority;
848    spin_unlock(&mem->reclaim_param_lock);
849}
850
851static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
852{
853    unsigned long active;
854    unsigned long inactive;
855    unsigned long gb;
856    unsigned long inactive_ratio;
857
858    inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_ANON);
859    active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_ANON);
860
861    gb = (inactive + active) >> (30 - PAGE_SHIFT);
862    if (gb)
863        inactive_ratio = int_sqrt(10 * gb);
864    else
865        inactive_ratio = 1;
866
867    if (present_pages) {
868        present_pages[0] = inactive;
869        present_pages[1] = active;
870    }
871
872    return inactive_ratio;
873}
874
875int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
876{
877    unsigned long active;
878    unsigned long inactive;
879    unsigned long present_pages[2];
880    unsigned long inactive_ratio;
881
882    inactive_ratio = calc_inactive_ratio(memcg, present_pages);
883
884    inactive = present_pages[0];
885    active = present_pages[1];
886
887    if (inactive * inactive_ratio < active)
888        return 1;
889
890    return 0;
891}
892
893int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
894{
895    unsigned long active;
896    unsigned long inactive;
897
898    inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE);
899    active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE);
900
901    return (active > inactive);
902}
903
904unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
905                       struct zone *zone,
906                       enum lru_list lru)
907{
908    int nid = zone->zone_pgdat->node_id;
909    int zid = zone_idx(zone);
910    struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
911
912    return MEM_CGROUP_ZSTAT(mz, lru);
913}
914
915struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
916                              struct zone *zone)
917{
918    int nid = zone->zone_pgdat->node_id;
919    int zid = zone_idx(zone);
920    struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
921
922    return &mz->reclaim_stat;
923}
924
925struct zone_reclaim_stat *
926mem_cgroup_get_reclaim_stat_from_page(struct page *page)
927{
928    struct page_cgroup *pc;
929    struct mem_cgroup_per_zone *mz;
930
931    if (mem_cgroup_disabled())
932        return NULL;
933
934    pc = lookup_page_cgroup(page);
935    /*
936     * Used bit is set without atomic ops but after smp_wmb().
937     * For making pc->mem_cgroup visible, insert smp_rmb() here.
938     */
939    smp_rmb();
940    if (!PageCgroupUsed(pc))
941        return NULL;
942
943    mz = page_cgroup_zoneinfo(pc);
944    if (!mz)
945        return NULL;
946
947    return &mz->reclaim_stat;
948}
949
950unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
951                    struct list_head *dst,
952                    unsigned long *scanned, int order,
953                    int mode, struct zone *z,
954                    struct mem_cgroup *mem_cont,
955                    int active, int file)
956{
957    unsigned long nr_taken = 0;
958    struct page *page;
959    unsigned long scan;
960    LIST_HEAD(pc_list);
961    struct list_head *src;
962    struct page_cgroup *pc, *tmp;
963    int nid = z->zone_pgdat->node_id;
964    int zid = zone_idx(z);
965    struct mem_cgroup_per_zone *mz;
966    int lru = LRU_FILE * file + active;
967    int ret;
968
969    BUG_ON(!mem_cont);
970    mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
971    src = &mz->lists[lru];
972
973    scan = 0;
974    list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
975        if (scan >= nr_to_scan)
976            break;
977
978        page = pc->page;
979        if (unlikely(!PageCgroupUsed(pc)))
980            continue;
981        if (unlikely(!PageLRU(page)))
982            continue;
983
984        scan++;
985        ret = __isolate_lru_page(page, mode, file);
986        switch (ret) {
987        case 0:
988            list_move(&page->lru, dst);
989            mem_cgroup_del_lru(page);
990            nr_taken++;
991            break;
992        case -EBUSY:
993            /* we don't affect global LRU but rotate in our LRU */
994            mem_cgroup_rotate_lru_list(page, page_lru(page));
995            break;
996        default:
997            break;
998        }
999    }
1000
1001    *scanned = scan;
1002    return nr_taken;
1003}
1004
1005#define mem_cgroup_from_res_counter(counter, member) \
1006    container_of(counter, struct mem_cgroup, member)
1007
1008static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
1009{
1010    if (do_swap_account) {
1011        if (res_counter_check_under_limit(&mem->res) &&
1012            res_counter_check_under_limit(&mem->memsw))
1013            return true;
1014    } else
1015        if (res_counter_check_under_limit(&mem->res))
1016            return true;
1017    return false;
1018}
1019
1020static unsigned int get_swappiness(struct mem_cgroup *memcg)
1021{
1022    struct cgroup *cgrp = memcg->css.cgroup;
1023    unsigned int swappiness;
1024
1025    /* root ? */
1026    if (cgrp->parent == NULL)
1027        return vm_swappiness;
1028
1029    spin_lock(&memcg->reclaim_param_lock);
1030    swappiness = memcg->swappiness;
1031    spin_unlock(&memcg->reclaim_param_lock);
1032
1033    return swappiness;
1034}
1035
1036static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
1037{
1038    int *val = data;
1039    (*val)++;
1040    return 0;
1041}
1042
1043/**
1044 * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
1045 * @memcg: The memory cgroup that went over limit
1046 * @p: Task that is going to be killed
1047 *
1048 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1049 * enabled
1050 */
1051void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
1052{
1053    struct cgroup *task_cgrp;
1054    struct cgroup *mem_cgrp;
1055    /*
1056     * Need a buffer in BSS, can't rely on allocations. The code relies
1057     * on the assumption that OOM is serialized for memory controller.
1058     * If this assumption is broken, revisit this code.
1059     */
1060    static char memcg_name[PATH_MAX];
1061    int ret;
1062
1063    if (!memcg || !p)
1064        return;
1065
1066
1067    rcu_read_lock();
1068
1069    mem_cgrp = memcg->css.cgroup;
1070    task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
1071
1072    ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
1073    if (ret < 0) {
1074        /*
1075         * Unfortunately, we are unable to convert to a useful name
1076         * But we'll still print out the usage information
1077         */
1078        rcu_read_unlock();
1079        goto done;
1080    }
1081    rcu_read_unlock();
1082
1083    printk(KERN_INFO "Task in %s killed", memcg_name);
1084
1085    rcu_read_lock();
1086    ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
1087    if (ret < 0) {
1088        rcu_read_unlock();
1089        goto done;
1090    }
1091    rcu_read_unlock();
1092
1093    /*
1094     * Continues from above, so we don't need an KERN_ level
1095     */
1096    printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
1097done:
1098
1099    printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
1100        res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
1101        res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
1102        res_counter_read_u64(&memcg->res, RES_FAILCNT));
1103    printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
1104        "failcnt %llu\n",
1105        res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
1106        res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
1107        res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1108}
1109
1110/*
1111 * This function returns the number of memcg under hierarchy tree. Returns
1112 * 1(self count) if no children.
1113 */
1114static int mem_cgroup_count_children(struct mem_cgroup *mem)
1115{
1116    int num = 0;
1117     mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb);
1118    return num;
1119}
1120
1121/*
1122 * Visit the first child (need not be the first child as per the ordering
1123 * of the cgroup list, since we track last_scanned_child) of @mem and use
1124 * that to reclaim free pages from.
1125 */
1126static struct mem_cgroup *
1127mem_cgroup_select_victim(struct mem_cgroup *root_mem)
1128{
1129    struct mem_cgroup *ret = NULL;
1130    struct cgroup_subsys_state *css;
1131    int nextid, found;
1132
1133    if (!root_mem->use_hierarchy) {
1134        css_get(&root_mem->css);
1135        ret = root_mem;
1136    }
1137
1138    while (!ret) {
1139        rcu_read_lock();
1140        nextid = root_mem->last_scanned_child + 1;
1141        css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css,
1142                   &found);
1143        if (css && css_tryget(css))
1144            ret = container_of(css, struct mem_cgroup, css);
1145
1146        rcu_read_unlock();
1147        /* Updates scanning parameter */
1148        spin_lock(&root_mem->reclaim_param_lock);
1149        if (!css) {
1150            /* this means start scan from ID:1 */
1151            root_mem->last_scanned_child = 0;
1152        } else
1153            root_mem->last_scanned_child = found;
1154        spin_unlock(&root_mem->reclaim_param_lock);
1155    }
1156
1157    return ret;
1158}
1159
1160/*
1161 * Scan the hierarchy if needed to reclaim memory. We remember the last child
1162 * we reclaimed from, so that we don't end up penalizing one child extensively
1163 * based on its position in the children list.
1164 *
1165 * root_mem is the original ancestor that we've been reclaim from.
1166 *
1167 * We give up and return to the caller when we visit root_mem twice.
1168 * (other groups can be removed while we're walking....)
1169 *
1170 * If shrink==true, for avoiding to free too much, this returns immedieately.
1171 */
1172static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
1173                        struct zone *zone,
1174                        gfp_t gfp_mask,
1175                        unsigned long reclaim_options)
1176{
1177    struct mem_cgroup *victim;
1178    int ret, total = 0;
1179    int loop = 0;
1180    bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
1181    bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
1182    bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
1183    unsigned long excess = mem_cgroup_get_excess(root_mem);
1184
1185    /* If memsw_is_minimum==1, swap-out is of-no-use. */
1186    if (root_mem->memsw_is_minimum)
1187        noswap = true;
1188
1189    while (1) {
1190        victim = mem_cgroup_select_victim(root_mem);
1191        if (victim == root_mem) {
1192            loop++;
1193            if (loop >= 1)
1194                drain_all_stock_async();
1195            if (loop >= 2) {
1196                /*
1197                 * If we have not been able to reclaim
1198                 * anything, it might because there are
1199                 * no reclaimable pages under this hierarchy
1200                 */
1201                if (!check_soft || !total) {
1202                    css_put(&victim->css);
1203                    break;
1204                }
1205                /*
1206                 * We want to do more targetted reclaim.
1207                 * excess >> 2 is not to excessive so as to
1208                 * reclaim too much, nor too less that we keep
1209                 * coming back to reclaim from this cgroup
1210                 */
1211                if (total >= (excess >> 2) ||
1212                    (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) {
1213                    css_put(&victim->css);
1214                    break;
1215                }
1216            }
1217        }
1218        if (!mem_cgroup_local_usage(victim)) {
1219            /* this cgroup's local usage == 0 */
1220            css_put(&victim->css);
1221            continue;
1222        }
1223        /* we use swappiness of local cgroup */
1224        if (check_soft)
1225            ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
1226                noswap, get_swappiness(victim), zone,
1227                zone->zone_pgdat->node_id);
1228        else
1229            ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
1230                        noswap, get_swappiness(victim));
1231        css_put(&victim->css);
1232        /*
1233         * At shrinking usage, we can't check we should stop here or
1234         * reclaim more. It's depends on callers. last_scanned_child
1235         * will work enough for keeping fairness under tree.
1236         */
1237        if (shrink)
1238            return ret;
1239        total += ret;
1240        if (check_soft) {
1241            if (res_counter_check_under_soft_limit(&root_mem->res))
1242                return total;
1243        } else if (mem_cgroup_check_under_limit(root_mem))
1244            return 1 + total;
1245    }
1246    return total;
1247}
1248
1249static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data)
1250{
1251    int *val = (int *)data;
1252    int x;
1253    /*
1254     * Logically, we can stop scanning immediately when we find
1255     * a memcg is already locked. But condidering unlock ops and
1256     * creation/removal of memcg, scan-all is simple operation.
1257     */
1258    x = atomic_inc_return(&mem->oom_lock);
1259    *val = max(x, *val);
1260    return 0;
1261}
1262/*
1263 * Check OOM-Killer is already running under our hierarchy.
1264 * If someone is running, return false.
1265 */
1266static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
1267{
1268    int lock_count = 0;
1269
1270    mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb);
1271
1272    if (lock_count == 1)
1273        return true;
1274    return false;
1275}
1276
1277static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data)
1278{
1279    /*
1280     * When a new child is created while the hierarchy is under oom,
1281     * mem_cgroup_oom_lock() may not be called. We have to use
1282     * atomic_add_unless() here.
1283     */
1284    atomic_add_unless(&mem->oom_lock, -1, 0);
1285    return 0;
1286}
1287
1288static void mem_cgroup_oom_unlock(struct mem_cgroup *mem)
1289{
1290    mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb);
1291}
1292
1293static DEFINE_MUTEX(memcg_oom_mutex);
1294static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1295
1296/*
1297 * try to call OOM killer. returns false if we should exit memory-reclaim loop.
1298 */
1299bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
1300{
1301    DEFINE_WAIT(wait);
1302    bool locked;
1303
1304    /* At first, try to OOM lock hierarchy under mem.*/
1305    mutex_lock(&memcg_oom_mutex);
1306    locked = mem_cgroup_oom_lock(mem);
1307    /*
1308     * Even if signal_pending(), we can't quit charge() loop without
1309     * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
1310     * under OOM is always welcomed, use TASK_KILLABLE here.
1311     */
1312    if (!locked)
1313        prepare_to_wait(&memcg_oom_waitq, &wait, TASK_KILLABLE);
1314    mutex_unlock(&memcg_oom_mutex);
1315
1316    if (locked)
1317        mem_cgroup_out_of_memory(mem, mask);
1318    else {
1319        schedule();
1320        finish_wait(&memcg_oom_waitq, &wait);
1321    }
1322    mutex_lock(&memcg_oom_mutex);
1323    mem_cgroup_oom_unlock(mem);
1324    /*
1325     * Here, we use global waitq .....more fine grained waitq ?
1326     * Assume following hierarchy.
1327     * A/
1328     * 01
1329     * 02
1330     * assume OOM happens both in A and 01 at the same time. Tthey are
1331     * mutually exclusive by lock. (kill in 01 helps A.)
1332     * When we use per memcg waitq, we have to wake up waiters on A and 02
1333     * in addtion to waiters on 01. We use global waitq for avoiding mess.
1334     * It will not be a big problem.
1335     * (And a task may be moved to other groups while it's waiting for OOM.)
1336     */
1337    wake_up_all(&memcg_oom_waitq);
1338    mutex_unlock(&memcg_oom_mutex);
1339
1340    if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
1341        return false;
1342    /* Give chance to dying process */
1343    schedule_timeout(1);
1344    return true;
1345}
1346
1347/*
1348 * Currently used to update mapped file statistics, but the routine can be
1349 * generalized to update other statistics as well.
1350 */
1351void mem_cgroup_update_file_mapped(struct page *page, int val)
1352{
1353    struct mem_cgroup *mem;
1354    struct page_cgroup *pc;
1355
1356    pc = lookup_page_cgroup(page);
1357    if (unlikely(!pc))
1358        return;
1359
1360    lock_page_cgroup(pc);
1361    mem = pc->mem_cgroup;
1362    if (!mem || !PageCgroupUsed(pc))
1363        goto done;
1364
1365    /*
1366     * Preemption is already disabled. We can use __this_cpu_xxx
1367     */
1368    if (val > 0) {
1369        __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1370        SetPageCgroupFileMapped(pc);
1371    } else {
1372        __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1373        ClearPageCgroupFileMapped(pc);
1374    }
1375
1376done:
1377    unlock_page_cgroup(pc);
1378}
1379
1380/*
1381 * size of first charge trial. "32" comes from vmscan.c's magic value.
1382 * TODO: maybe necessary to use big numbers in big irons.
1383 */
1384#define CHARGE_SIZE (32 * PAGE_SIZE)
1385struct memcg_stock_pcp {
1386    struct mem_cgroup *cached; /* this never be root cgroup */
1387    int charge;
1388    struct work_struct work;
1389};
1390static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
1391static atomic_t memcg_drain_count;
1392
1393/*
1394 * Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed
1395 * from local stock and true is returned. If the stock is 0 or charges from a
1396 * cgroup which is not current target, returns false. This stock will be
1397 * refilled.
1398 */
1399static bool consume_stock(struct mem_cgroup *mem)
1400{
1401    struct memcg_stock_pcp *stock;
1402    bool ret = true;
1403
1404    stock = &get_cpu_var(memcg_stock);
1405    if (mem == stock->cached && stock->charge)
1406        stock->charge -= PAGE_SIZE;
1407    else /* need to call res_counter_charge */
1408        ret = false;
1409    put_cpu_var(memcg_stock);
1410    return ret;
1411}
1412
1413/*
1414 * Returns stocks cached in percpu to res_counter and reset cached information.
1415 */
1416static void drain_stock(struct memcg_stock_pcp *stock)
1417{
1418    struct mem_cgroup *old = stock->cached;
1419
1420    if (stock->charge) {
1421        res_counter_uncharge(&old->res, stock->charge);
1422        if (do_swap_account)
1423            res_counter_uncharge(&old->memsw, stock->charge);
1424    }
1425    stock->cached = NULL;
1426    stock->charge = 0;
1427}
1428
1429/*
1430 * This must be called under preempt disabled or must be called by
1431 * a thread which is pinned to local cpu.
1432 */
1433static void drain_local_stock(struct work_struct *dummy)
1434{
1435    struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
1436    drain_stock(stock);
1437}
1438
1439/*
1440 * Cache charges(val) which is from res_counter, to local per_cpu area.
1441 * This will be consumed by consumt_stock() function, later.
1442 */
1443static void refill_stock(struct mem_cgroup *mem, int val)
1444{
1445    struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
1446
1447    if (stock->cached != mem) { /* reset if necessary */
1448        drain_stock(stock);
1449        stock->cached = mem;
1450    }
1451    stock->charge += val;
1452    put_cpu_var(memcg_stock);
1453}
1454
1455/*
1456 * Tries to drain stocked charges in other cpus. This function is asynchronous
1457 * and just put a work per cpu for draining localy on each cpu. Caller can
1458 * expects some charges will be back to res_counter later but cannot wait for
1459 * it.
1460 */
1461static void drain_all_stock_async(void)
1462{
1463    int cpu;
1464    /* This function is for scheduling "drain" in asynchronous way.
1465     * The result of "drain" is not directly handled by callers. Then,
1466     * if someone is calling drain, we don't have to call drain more.
1467     * Anyway, WORK_STRUCT_PENDING check in queue_work_on() will catch if
1468     * there is a race. We just do loose check here.
1469     */
1470    if (atomic_read(&memcg_drain_count))
1471        return;
1472    /* Notify other cpus that system-wide "drain" is running */
1473    atomic_inc(&memcg_drain_count);
1474    get_online_cpus();
1475    for_each_online_cpu(cpu) {
1476        struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
1477        schedule_work_on(cpu, &stock->work);
1478    }
1479     put_online_cpus();
1480    atomic_dec(&memcg_drain_count);
1481    /* We don't wait for flush_work */
1482}
1483
1484/* This is a synchronous drain interface. */
1485static void drain_all_stock_sync(void)
1486{
1487    /* called when force_empty is called */
1488    atomic_inc(&memcg_drain_count);
1489    schedule_on_each_cpu(drain_local_stock);
1490    atomic_dec(&memcg_drain_count);
1491}
1492
1493static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb,
1494                    unsigned long action,
1495                    void *hcpu)
1496{
1497    int cpu = (unsigned long)hcpu;
1498    struct memcg_stock_pcp *stock;
1499
1500    if (action != CPU_DEAD)
1501        return NOTIFY_OK;
1502    stock = &per_cpu(memcg_stock, cpu);
1503    drain_stock(stock);
1504    return NOTIFY_OK;
1505}
1506
1507/*
1508 * Unlike exported interface, "oom" parameter is added. if oom==true,
1509 * oom-killer can be invoked.
1510 */
1511static int __mem_cgroup_try_charge(struct mm_struct *mm,
1512            gfp_t gfp_mask, struct mem_cgroup **memcg, bool oom)
1513{
1514    struct mem_cgroup *mem, *mem_over_limit;
1515    int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
1516    struct res_counter *fail_res;
1517    int csize = CHARGE_SIZE;
1518
1519    /*
1520     * Unlike gloval-vm's OOM-kill, we're not in memory shortage
1521     * in system level. So, allow to go ahead dying process in addition to
1522     * MEMDIE process.
1523     */
1524    if (unlikely(test_thread_flag(TIF_MEMDIE)
1525             || fatal_signal_pending(current)))
1526        goto bypass;
1527
1528    /*
1529     * We always charge the cgroup the mm_struct belongs to.
1530     * The mm_struct's mem_cgroup changes on task migration if the
1531     * thread group leader migrates. It's possible that mm is not
1532     * set, if so charge the init_mm (happens for pagecache usage).
1533     */
1534    mem = *memcg;
1535    if (likely(!mem)) {
1536        mem = try_get_mem_cgroup_from_mm(mm);
1537        *memcg = mem;
1538    } else {
1539        css_get(&mem->css);
1540    }
1541    if (unlikely(!mem))
1542        return 0;
1543
1544    VM_BUG_ON(css_is_removed(&mem->css));
1545    if (mem_cgroup_is_root(mem))
1546        goto done;
1547
1548    while (1) {
1549        int ret = 0;
1550        unsigned long flags = 0;
1551
1552        if (consume_stock(mem))
1553            goto done;
1554
1555        ret = res_counter_charge(&mem->res, csize, &fail_res);
1556        if (likely(!ret)) {
1557            if (!do_swap_account)
1558                break;
1559            ret = res_counter_charge(&mem->memsw, csize, &fail_res);
1560            if (likely(!ret))
1561                break;
1562            /* mem+swap counter fails */
1563            res_counter_uncharge(&mem->res, csize);
1564            flags |= MEM_CGROUP_RECLAIM_NOSWAP;
1565            mem_over_limit = mem_cgroup_from_res_counter(fail_res,
1566                                    memsw);
1567        } else
1568            /* mem counter fails */
1569            mem_over_limit = mem_cgroup_from_res_counter(fail_res,
1570                                    res);
1571
1572        /* reduce request size and retry */
1573        if (csize > PAGE_SIZE) {
1574            csize = PAGE_SIZE;
1575            continue;
1576        }
1577        if (!(gfp_mask & __GFP_WAIT))
1578            goto nomem;
1579
1580        ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
1581                        gfp_mask, flags);
1582        if (ret)
1583            continue;
1584
1585        /*
1586         * try_to_free_mem_cgroup_pages() might not give us a full
1587         * picture of reclaim. Some pages are reclaimed and might be
1588         * moved to swap cache or just unmapped from the cgroup.
1589         * Check the limit again to see if the reclaim reduced the
1590         * current usage of the cgroup before giving up
1591         *
1592         */
1593        if (mem_cgroup_check_under_limit(mem_over_limit))
1594            continue;
1595
1596        /* try to avoid oom while someone is moving charge */
1597        if (mc.moving_task && current != mc.moving_task) {
1598            struct mem_cgroup *from, *to;
1599            bool do_continue = false;
1600            /*
1601             * There is a small race that "from" or "to" can be
1602             * freed by rmdir, so we use css_tryget().
1603             */
1604            rcu_read_lock();
1605            from = mc.from;
1606            to = mc.to;
1607            if (from && css_tryget(&from->css)) {
1608                if (mem_over_limit->use_hierarchy)
1609                    do_continue = css_is_ancestor(
1610                            &from->css,
1611                            &mem_over_limit->css);
1612                else
1613                    do_continue = (from == mem_over_limit);
1614                css_put(&from->css);
1615            }
1616            if (!do_continue && to && css_tryget(&to->css)) {
1617                if (mem_over_limit->use_hierarchy)
1618                    do_continue = css_is_ancestor(
1619                            &to->css,
1620                            &mem_over_limit->css);
1621                else
1622                    do_continue = (to == mem_over_limit);
1623                css_put(&to->css);
1624            }
1625            rcu_read_unlock();
1626            if (do_continue) {
1627                DEFINE_WAIT(wait);
1628                prepare_to_wait(&mc.waitq, &wait,
1629                            TASK_INTERRUPTIBLE);
1630                /* moving charge context might have finished. */
1631                if (mc.moving_task)
1632                    schedule();
1633                finish_wait(&mc.waitq, &wait);
1634                continue;
1635            }
1636        }
1637
1638        if (!nr_retries--) {
1639            if (!oom)
1640                goto nomem;
1641            if (mem_cgroup_handle_oom(mem_over_limit, gfp_mask)) {
1642                nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
1643                continue;
1644            }
1645            /* When we reach here, current task is dying .*/
1646            css_put(&mem->css);
1647            goto bypass;
1648        }
1649    }
1650    if (csize > PAGE_SIZE)
1651        refill_stock(mem, csize - PAGE_SIZE);
1652done:
1653    return 0;
1654nomem:
1655    css_put(&mem->css);
1656    return -ENOMEM;
1657bypass:
1658    *memcg = NULL;
1659    return 0;
1660}
1661
1662/*
1663 * Somemtimes we have to undo a charge we got by try_charge().
1664 * This function is for that and do uncharge, put css's refcnt.
1665 * gotten by try_charge().
1666 */
1667static void __mem_cgroup_cancel_charge(struct mem_cgroup *mem,
1668                            unsigned long count)
1669{
1670    if (!mem_cgroup_is_root(mem)) {
1671        res_counter_uncharge(&mem->res, PAGE_SIZE * count);
1672        if (do_swap_account)
1673            res_counter_uncharge(&mem->memsw, PAGE_SIZE * count);
1674        VM_BUG_ON(test_bit(CSS_ROOT, &mem->css.flags));
1675        WARN_ON_ONCE(count > INT_MAX);
1676        __css_put(&mem->css, (int)count);
1677    }
1678    /* we don't need css_put for root */
1679}
1680
1681static void mem_cgroup_cancel_charge(struct mem_cgroup *mem)
1682{
1683    __mem_cgroup_cancel_charge(mem, 1);
1684}
1685
1686/*
1687 * A helper function to get mem_cgroup from ID. must be called under
1688 * rcu_read_lock(). The caller must check css_is_removed() or some if
1689 * it's concern. (dropping refcnt from swap can be called against removed
1690 * memcg.)
1691 */
1692static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
1693{
1694    struct cgroup_subsys_state *css;
1695
1696    /* ID 0 is unused ID */
1697    if (!id)
1698        return NULL;
1699    css = css_lookup(&mem_cgroup_subsys, id);
1700    if (!css)
1701        return NULL;
1702    return container_of(css, struct mem_cgroup, css);
1703}
1704
1705struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
1706{
1707    struct mem_cgroup *mem = NULL;
1708    struct page_cgroup *pc;
1709    unsigned short id;
1710    swp_entry_t ent;
1711
1712    VM_BUG_ON(!PageLocked(page));
1713
1714    pc = lookup_page_cgroup(page);
1715    lock_page_cgroup(pc);
1716    if (PageCgroupUsed(pc)) {
1717        mem = pc->mem_cgroup;
1718        if (mem && !css_tryget(&mem->css))
1719            mem = NULL;
1720    } else if (PageSwapCache(page)) {
1721        ent.val = page_private(page);
1722        id = lookup_swap_cgroup(ent);
1723        rcu_read_lock();
1724        mem = mem_cgroup_lookup(id);
1725        if (mem && !css_tryget(&mem->css))
1726            mem = NULL;
1727        rcu_read_unlock();
1728    }
1729    unlock_page_cgroup(pc);
1730    return mem;
1731}
1732
1733/*
1734 * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
1735 * USED state. If already USED, uncharge and return.
1736 */
1737
1738static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
1739                     struct page_cgroup *pc,
1740                     enum charge_type ctype)
1741{
1742    /* try_charge() can return NULL to *memcg, taking care of it. */
1743    if (!mem)
1744        return;
1745
1746    lock_page_cgroup(pc);
1747    if (unlikely(PageCgroupUsed(pc))) {
1748        unlock_page_cgroup(pc);
1749        mem_cgroup_cancel_charge(mem);
1750        return;
1751    }
1752
1753    pc->mem_cgroup = mem;
1754    /*
1755     * We access a page_cgroup asynchronously without lock_page_cgroup().
1756     * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
1757     * is accessed after testing USED bit. To make pc->mem_cgroup visible
1758     * before USED bit, we need memory barrier here.
1759     * See mem_cgroup_add_lru_list(), etc.
1760      */
1761    smp_wmb();
1762    switch (ctype) {
1763    case MEM_CGROUP_CHARGE_TYPE_CACHE:
1764    case MEM_CGROUP_CHARGE_TYPE_SHMEM:
1765        SetPageCgroupCache(pc);
1766        SetPageCgroupUsed(pc);
1767        break;
1768    case MEM_CGROUP_CHARGE_TYPE_MAPPED:
1769        ClearPageCgroupCache(pc);
1770        SetPageCgroupUsed(pc);
1771        break;
1772    default:
1773        break;
1774    }
1775
1776    mem_cgroup_charge_statistics(mem, pc, true);
1777
1778    unlock_page_cgroup(pc);
1779    /*
1780     * "charge_statistics" updated event counter. Then, check it.
1781     * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
1782     * if they exceeds softlimit.
1783     */
1784    memcg_check_events(mem, pc->page);
1785}
1786
1787/**
1788 * __mem_cgroup_move_account - move account of the page
1789 * @pc: page_cgroup of the page.
1790 * @from: mem_cgroup which the page is moved from.
1791 * @to: mem_cgroup which the page is moved to. @from != @to.
1792 * @uncharge: whether we should call uncharge and css_put against @from.
1793 *
1794 * The caller must confirm following.
1795 * - page is not on LRU (isolate_page() is useful.)
1796 * - the pc is locked, used, and ->mem_cgroup points to @from.
1797 *
1798 * This function doesn't do "charge" nor css_get to new cgroup. It should be
1799 * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
1800 * true, this function does "uncharge" from old cgroup, but it doesn't if
1801 * @uncharge is false, so a caller should do "uncharge".
1802 */
1803
1804static void __mem_cgroup_move_account(struct page_cgroup *pc,
1805    struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
1806{
1807    VM_BUG_ON(from == to);
1808    VM_BUG_ON(PageLRU(pc->page));
1809    VM_BUG_ON(!PageCgroupLocked(pc));
1810    VM_BUG_ON(!PageCgroupUsed(pc));
1811    VM_BUG_ON(pc->mem_cgroup != from);
1812
1813    if (PageCgroupFileMapped(pc)) {
1814        /* Update mapped_file data for mem_cgroup */
1815        preempt_disable();
1816        __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1817        __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1818        preempt_enable();
1819    }
1820    mem_cgroup_charge_statistics(from, pc, false);
1821    if (uncharge)
1822        /* This is not "cancel", but cancel_charge does all we need. */
1823        mem_cgroup_cancel_charge(from);
1824
1825    /* caller should have done css_get */
1826    pc->mem_cgroup = to;
1827    mem_cgroup_charge_statistics(to, pc, true);
1828    /*
1829     * We charges against "to" which may not have any tasks. Then, "to"
1830     * can be under rmdir(). But in current implementation, caller of
1831     * this function is just force_empty() and move charge, so it's
1832     * garanteed that "to" is never removed. So, we don't check rmdir
1833     * status here.
1834     */
1835}
1836
1837/*
1838 * check whether the @pc is valid for moving account and call
1839 * __mem_cgroup_move_account()
1840 */
1841static int mem_cgroup_move_account(struct page_cgroup *pc,
1842        struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
1843{
1844    int ret = -EINVAL;
1845    lock_page_cgroup(pc);
1846    if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
1847        __mem_cgroup_move_account(pc, from, to, uncharge);
1848        ret = 0;
1849    }
1850    unlock_page_cgroup(pc);
1851    /*
1852     * check events
1853     */
1854    memcg_check_events(to, pc->page);
1855    memcg_check_events(from, pc->page);
1856    return ret;
1857}
1858
1859/*
1860 * move charges to its parent.
1861 */
1862
1863static int mem_cgroup_move_parent(struct page_cgroup *pc,
1864                  struct mem_cgroup *child,
1865                  gfp_t gfp_mask)
1866{
1867    struct page *page = pc->page;
1868    struct cgroup *cg = child->css.cgroup;
1869    struct cgroup *pcg = cg->parent;
1870    struct mem_cgroup *parent;
1871    int ret;
1872
1873    /* Is ROOT ? */
1874    if (!pcg)
1875        return -EINVAL;
1876
1877    ret = -EBUSY;
1878    if (!get_page_unless_zero(page))
1879        goto out;
1880    if (isolate_lru_page(page))
1881        goto put;
1882
1883    parent = mem_cgroup_from_cont(pcg);
1884    ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
1885    if (ret || !parent)
1886        goto put_back;
1887
1888    ret = mem_cgroup_move_account(pc, child, parent, true);
1889    if (ret)
1890        mem_cgroup_cancel_charge(parent);
1891put_back:
1892    putback_lru_page(page);
1893put:
1894    put_page(page);
1895out:
1896    return ret;
1897}
1898
1899/*
1900 * Charge the memory controller for page usage.
1901 * Return
1902 * 0 if the charge was successful
1903 * < 0 if the cgroup is over its limit
1904 */
1905static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
1906                gfp_t gfp_mask, enum charge_type ctype,
1907                struct mem_cgroup *memcg)
1908{
1909    struct mem_cgroup *mem;
1910    struct page_cgroup *pc;
1911    int ret;
1912
1913    pc = lookup_page_cgroup(page);
1914    /* can happen at boot */
1915    if (unlikely(!pc))
1916        return 0;
1917    prefetchw(pc);
1918
1919    mem = memcg;
1920    ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
1921    if (ret || !mem)
1922        return ret;
1923
1924    __mem_cgroup_commit_charge(mem, pc, ctype);
1925    return 0;
1926}
1927
1928int mem_cgroup_newpage_charge(struct page *page,
1929                  struct mm_struct *mm, gfp_t gfp_mask)
1930{
1931    if (mem_cgroup_disabled())
1932        return 0;
1933    if (PageCompound(page))
1934        return 0;
1935    /*
1936     * If already mapped, we don't have to account.
1937     * If page cache, page->mapping has address_space.
1938     * But page->mapping may have out-of-use anon_vma pointer,
1939     * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
1940     * is NULL.
1941       */
1942    if (page_mapped(page) || (page->mapping && !PageAnon(page)))
1943        return 0;
1944    if (unlikely(!mm))
1945        mm = &init_mm;
1946    return mem_cgroup_charge_common(page, mm, gfp_mask,
1947                MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
1948}
1949
1950static void
1951__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
1952                    enum charge_type ctype);
1953
1954int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
1955                gfp_t gfp_mask)
1956{
1957    struct mem_cgroup *mem = NULL;
1958    int ret;
1959
1960    if (mem_cgroup_disabled())
1961        return 0;
1962    if (PageCompound(page))
1963        return 0;
1964    /*
1965     * Corner case handling. This is called from add_to_page_cache()
1966     * in usual. But some FS (shmem) precharges this page before calling it
1967     * and call add_to_page_cache() with GFP_NOWAIT.
1968     *
1969     * For GFP_NOWAIT case, the page may be pre-charged before calling
1970     * add_to_page_cache(). (See shmem.c) check it here and avoid to call
1971     * charge twice. (It works but has to pay a bit larger cost.)
1972     * And when the page is SwapCache, it should take swap information
1973     * into account. This is under lock_page() now.
1974     */
1975    if (!(gfp_mask & __GFP_WAIT)) {
1976        struct page_cgroup *pc;
1977
1978
1979        pc = lookup_page_cgroup(page);
1980        if (!pc)
1981            return 0;
1982        lock_page_cgroup(pc);
1983        if (PageCgroupUsed(pc)) {
1984            unlock_page_cgroup(pc);
1985            return 0;
1986        }
1987        unlock_page_cgroup(pc);
1988    }
1989
1990    if (unlikely(!mm && !mem))
1991        mm = &init_mm;
1992
1993    if (page_is_file_cache(page))
1994        return mem_cgroup_charge_common(page, mm, gfp_mask,
1995                MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
1996
1997    /* shmem */
1998    if (PageSwapCache(page)) {
1999        ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2000        if (!ret)
2001            __mem_cgroup_commit_charge_swapin(page, mem,
2002                    MEM_CGROUP_CHARGE_TYPE_SHMEM);
2003    } else
2004        ret = mem_cgroup_charge_common(page, mm, gfp_mask,
2005                    MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
2006
2007    return ret;
2008}
2009
2010/*
2011 * While swap-in, try_charge -> commit or cancel, the page is locked.
2012 * And when try_charge() successfully returns, one refcnt to memcg without
2013 * struct page_cgroup is acquired. This refcnt will be consumed by
2014 * "commit()" or removed by "cancel()"
2015 */
2016int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
2017                 struct page *page,
2018                 gfp_t mask, struct mem_cgroup **ptr)
2019{
2020    struct mem_cgroup *mem;
2021    int ret;
2022
2023    if (mem_cgroup_disabled())
2024        return 0;
2025
2026    if (!do_swap_account)
2027        goto charge_cur_mm;
2028    /*
2029     * A racing thread's fault, or swapoff, may have already updated
2030     * the pte, and even removed page from swap cache: in those cases
2031     * do_swap_page()'s pte_same() test will fail; but there's also a
2032     * KSM case which does need to charge the page.
2033     */
2034    if (!PageSwapCache(page))
2035        goto charge_cur_mm;
2036    mem = try_get_mem_cgroup_from_page(page);
2037    if (!mem)
2038        goto charge_cur_mm;
2039    *ptr = mem;
2040    ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
2041    /* drop extra refcnt from tryget */
2042    css_put(&mem->css);
2043    return ret;
2044charge_cur_mm:
2045    if (unlikely(!mm))
2046        mm = &init_mm;
2047    return __mem_cgroup_try_charge(mm, mask, ptr, true);
2048}
2049
2050static void
2051__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2052                    enum charge_type ctype)
2053{
2054    struct page_cgroup *pc;
2055
2056    if (mem_cgroup_disabled())
2057        return;
2058    if (!ptr)
2059        return;
2060    cgroup_exclude_rmdir(&ptr->css);
2061    pc = lookup_page_cgroup(page);
2062    mem_cgroup_lru_del_before_commit_swapcache(page);
2063    __mem_cgroup_commit_charge(ptr, pc, ctype);
2064    mem_cgroup_lru_add_after_commit_swapcache(page);
2065    /*
2066     * Now swap is on-memory. This means this page may be
2067     * counted both as mem and swap....double count.
2068     * Fix it by uncharging from memsw. Basically, this SwapCache is stable
2069     * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
2070     * may call delete_from_swap_cache() before reach here.
2071     */
2072    if (do_swap_account && PageSwapCache(page)) {
2073        swp_entry_t ent = {.val = page_private(page)};
2074        unsigned short id;
2075        struct mem_cgroup *memcg;
2076
2077        id = swap_cgroup_record(ent, 0);
2078        rcu_read_lock();
2079        memcg = mem_cgroup_lookup(id);
2080        if (memcg) {
2081            /*
2082             * This recorded memcg can be obsolete one. So, avoid
2083             * calling css_tryget
2084             */
2085            if (!mem_cgroup_is_root(memcg))
2086                res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2087            mem_cgroup_swap_statistics(memcg, false);
2088            mem_cgroup_put(memcg);
2089        }
2090        rcu_read_unlock();
2091    }
2092    /*
2093     * At swapin, we may charge account against cgroup which has no tasks.
2094     * So, rmdir()->pre_destroy() can be called while we do this charge.
2095     * In that case, we need to call pre_destroy() again. check it here.
2096     */
2097    cgroup_release_and_wakeup_rmdir(&ptr->css);
2098}
2099
2100void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
2101{
2102    __mem_cgroup_commit_charge_swapin(page, ptr,
2103                    MEM_CGROUP_CHARGE_TYPE_MAPPED);
2104}
2105
2106void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
2107{
2108    if (mem_cgroup_disabled())
2109        return;
2110    if (!mem)
2111        return;
2112    mem_cgroup_cancel_charge(mem);
2113}
2114
2115static void
2116__do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype)
2117{
2118    struct memcg_batch_info *batch = NULL;
2119    bool uncharge_memsw = true;
2120    /* If swapout, usage of swap doesn't decrease */
2121    if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2122        uncharge_memsw = false;
2123    /*
2124     * do_batch > 0 when unmapping pages or inode invalidate/truncate.
2125     * In those cases, all pages freed continously can be expected to be in
2126     * the same cgroup and we have chance to coalesce uncharges.
2127     * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
2128     * because we want to do uncharge as soon as possible.
2129     */
2130    if (!current->memcg_batch.do_batch || test_thread_flag(TIF_MEMDIE))
2131        goto direct_uncharge;
2132
2133    batch = &current->memcg_batch;
2134    /*
2135     * In usual, we do css_get() when we remember memcg pointer.
2136     * But in this case, we keep res->usage until end of a series of
2137     * uncharges. Then, it's ok to ignore memcg's refcnt.
2138     */
2139    if (!batch->memcg)
2140        batch->memcg = mem;
2141    /*
2142     * In typical case, batch->memcg == mem. This means we can
2143     * merge a series of uncharges to an uncharge of res_counter.
2144     * If not, we uncharge res_counter ony by one.
2145     */
2146    if (batch->memcg != mem)
2147        goto direct_uncharge;
2148    /* remember freed charge and uncharge it later */
2149    batch->bytes += PAGE_SIZE;
2150    if (uncharge_memsw)
2151        batch->memsw_bytes += PAGE_SIZE;
2152    return;
2153direct_uncharge:
2154    res_counter_uncharge(&mem->res, PAGE_SIZE);
2155    if (uncharge_memsw)
2156        res_counter_uncharge(&mem->memsw, PAGE_SIZE);
2157    return;
2158}
2159
2160/*
2161 * uncharge if !page_mapped(page)
2162 */
2163static struct mem_cgroup *
2164__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
2165{
2166    struct page_cgroup *pc;
2167    struct mem_cgroup *mem = NULL;
2168    struct mem_cgroup_per_zone *mz;
2169
2170    if (mem_cgroup_disabled())
2171        return NULL;
2172
2173    if (PageSwapCache(page))
2174        return NULL;
2175
2176    /*
2177     * Check if our page_cgroup is valid
2178     */
2179    pc = lookup_page_cgroup(page);
2180    if (unlikely(!pc || !PageCgroupUsed(pc)))
2181        return NULL;
2182
2183    lock_page_cgroup(pc);
2184
2185    mem = pc->mem_cgroup;
2186
2187    if (!PageCgroupUsed(pc))
2188        goto unlock_out;
2189
2190    switch (ctype) {
2191    case MEM_CGROUP_CHARGE_TYPE_MAPPED:
2192    case MEM_CGROUP_CHARGE_TYPE_DROP:
2193        if (page_mapped(page))
2194            goto unlock_out;
2195        break;
2196    case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
2197        if (!PageAnon(page)) { /* Shared memory */
2198            if (page->mapping && !page_is_file_cache(page))
2199                goto unlock_out;
2200        } else if (page_mapped(page)) /* Anon */
2201                goto unlock_out;
2202        break;
2203    default:
2204        break;
2205    }
2206
2207    if (!mem_cgroup_is_root(mem))
2208        __do_uncharge(mem, ctype);
2209    if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2210        mem_cgroup_swap_statistics(mem, true);
2211    mem_cgroup_charge_statistics(mem, pc, false);
2212
2213    ClearPageCgroupUsed(pc);
2214    /*
2215     * pc->mem_cgroup is not cleared here. It will be accessed when it's
2216     * freed from LRU. This is safe because uncharged page is expected not
2217     * to be reused (freed soon). Exception is SwapCache, it's handled by
2218     * special functions.
2219     */
2220
2221    mz = page_cgroup_zoneinfo(pc);
2222    unlock_page_cgroup(pc);
2223
2224    memcg_check_events(mem, page);
2225    /* at swapout, this memcg will be accessed to record to swap */
2226    if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2227        css_put(&mem->css);
2228
2229    return mem;
2230
2231unlock_out:
2232    unlock_page_cgroup(pc);
2233    return NULL;
2234}
2235
2236void mem_cgroup_uncharge_page(struct page *page)
2237{
2238    /* early check. */
2239    if (page_mapped(page))
2240        return;
2241    if (page->mapping && !PageAnon(page))
2242        return;
2243    __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
2244}
2245
2246void mem_cgroup_uncharge_cache_page(struct page *page)
2247{
2248    VM_BUG_ON(page_mapped(page));
2249    VM_BUG_ON(page->mapping);
2250    __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
2251}
2252
2253/*
2254 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
2255 * In that cases, pages are freed continuously and we can expect pages
2256 * are in the same memcg. All these calls itself limits the number of
2257 * pages freed at once, then uncharge_start/end() is called properly.
2258 * This may be called prural(2) times in a context,
2259 */
2260
2261void mem_cgroup_uncharge_start(void)
2262{
2263    current->memcg_batch.do_batch++;
2264    /* We can do nest. */
2265    if (current->memcg_batch.do_batch == 1) {
2266        current->memcg_batch.memcg = NULL;
2267        current->memcg_batch.bytes = 0;
2268        current->memcg_batch.memsw_bytes = 0;
2269    }
2270}
2271
2272void mem_cgroup_uncharge_end(void)
2273{
2274    struct memcg_batch_info *batch = &current->memcg_batch;
2275
2276    if (!batch->do_batch)
2277        return;
2278
2279    batch->do_batch--;
2280    if (batch->do_batch) /* If stacked, do nothing. */
2281        return;
2282
2283    if (!batch->memcg)
2284        return;
2285    /*
2286     * This "batch->memcg" is valid without any css_get/put etc...
2287     * bacause we hide charges behind us.
2288     */
2289    if (batch->bytes)
2290        res_counter_uncharge(&batch->memcg->res, batch->bytes);
2291    if (batch->memsw_bytes)
2292        res_counter_uncharge(&batch->memcg->memsw, batch->memsw_bytes);
2293    /* forget this pointer (for sanity check) */
2294    batch->memcg = NULL;
2295}
2296
2297#ifdef CONFIG_SWAP
2298/*
2299 * called after __delete_from_swap_cache() and drop "page" account.
2300 * memcg information is recorded to swap_cgroup of "ent"
2301 */
2302void
2303mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
2304{
2305    struct mem_cgroup *memcg;
2306    int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
2307
2308    if (!swapout) /* this was a swap cache but the swap is unused ! */
2309        ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
2310
2311    memcg = __mem_cgroup_uncharge_common(page, ctype);
2312
2313    /* record memcg information */
2314    if (do_swap_account && swapout && memcg) {
2315        swap_cgroup_record(ent, css_id(&memcg->css));
2316        mem_cgroup_get(memcg);
2317    }
2318    if (swapout && memcg)
2319        css_put(&memcg->css);
2320}
2321#endif
2322
2323#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2324/*
2325 * called from swap_entry_free(). remove record in swap_cgroup and
2326 * uncharge "memsw" account.
2327 */
2328void mem_cgroup_uncharge_swap(swp_entry_t ent)
2329{
2330    struct mem_cgroup *memcg;
2331    unsigned short id;
2332
2333    if (!do_swap_account)
2334        return;
2335
2336    id = swap_cgroup_record(ent, 0);
2337    rcu_read_lock();
2338    memcg = mem_cgroup_lookup(id);
2339    if (memcg) {
2340        /*
2341         * We uncharge this because swap is freed.
2342         * This memcg can be obsolete one. We avoid calling css_tryget
2343         */
2344        if (!mem_cgroup_is_root(memcg))
2345            res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2346        mem_cgroup_swap_statistics(memcg, false);
2347        mem_cgroup_put(memcg);
2348    }
2349    rcu_read_unlock();
2350}
2351
2352/**
2353 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
2354 * @entry: swap entry to be moved
2355 * @from: mem_cgroup which the entry is moved from
2356 * @to: mem_cgroup which the entry is moved to
2357 * @need_fixup: whether we should fixup res_counters and refcounts.
2358 *
2359 * It succeeds only when the swap_cgroup's record for this entry is the same
2360 * as the mem_cgroup's id of @from.
2361 *
2362 * Returns 0 on success, -EINVAL on failure.
2363 *
2364 * The caller must have charged to @to, IOW, called res_counter_charge() about
2365 * both res and memsw, and called css_get().
2366 */
2367static int mem_cgroup_move_swap_account(swp_entry_t entry,
2368        struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2369{
2370    unsigned short old_id, new_id;
2371
2372    old_id = css_id(&from->css);
2373    new_id = css_id(&to->css);
2374
2375    if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
2376        mem_cgroup_swap_statistics(from, false);
2377        mem_cgroup_swap_statistics(to, true);
2378        /*
2379         * This function is only called from task migration context now.
2380         * It postpones res_counter and refcount handling till the end
2381         * of task migration(mem_cgroup_clear_mc()) for performance
2382         * improvement. But we cannot postpone mem_cgroup_get(to)
2383         * because if the process that has been moved to @to does
2384         * swap-in, the refcount of @to might be decreased to 0.
2385         */
2386        mem_cgroup_get(to);
2387        if (need_fixup) {
2388            if (!mem_cgroup_is_root(from))
2389                res_counter_uncharge(&from->memsw, PAGE_SIZE);
2390            mem_cgroup_put(from);
2391            /*
2392             * we charged both to->res and to->memsw, so we should
2393             * uncharge to->res.
2394             */
2395            if (!mem_cgroup_is_root(to))
2396                res_counter_uncharge(&to->res, PAGE_SIZE);
2397            css_put(&to->css);
2398        }
2399        return 0;
2400    }
2401    return -EINVAL;
2402}
2403#else
2404static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
2405        struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2406{
2407    return -EINVAL;
2408}
2409#endif
2410
2411/*
2412 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
2413 * page belongs to.
2414 */
2415int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
2416{
2417    struct page_cgroup *pc;
2418    struct mem_cgroup *mem = NULL;
2419    int ret = 0;
2420
2421    if (mem_cgroup_disabled())
2422        return 0;
2423
2424    pc = lookup_page_cgroup(page);
2425    lock_page_cgroup(pc);
2426    if (PageCgroupUsed(pc)) {
2427        mem = pc->mem_cgroup;
2428        css_get(&mem->css);
2429    }
2430    unlock_page_cgroup(pc);
2431
2432    if (mem) {
2433        ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
2434        css_put(&mem->css);
2435    }
2436    *ptr = mem;
2437    return ret;
2438}
2439
2440/* remove redundant charge if migration failed*/
2441void mem_cgroup_end_migration(struct mem_cgroup *mem,
2442        struct page *oldpage, struct page *newpage)
2443{
2444    struct page *target, *unused;
2445    struct page_cgroup *pc;
2446    enum charge_type ctype;
2447
2448    if (!mem)
2449        return;
2450    cgroup_exclude_rmdir(&mem->css);
2451    /* at migration success, oldpage->mapping is NULL. */
2452    if (oldpage->mapping) {
2453        target = oldpage;
2454        unused = NULL;
2455    } else {
2456        target = newpage;
2457        unused = oldpage;
2458    }
2459
2460    if (PageAnon(target))
2461        ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
2462    else if (page_is_file_cache(target))
2463        ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
2464    else
2465        ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
2466
2467    /* unused page is not on radix-tree now. */
2468    if (unused)
2469        __mem_cgroup_uncharge_common(unused, ctype);
2470
2471    pc = lookup_page_cgroup(target);
2472    /*
2473     * __mem_cgroup_commit_charge() check PCG_USED bit of page_cgroup.
2474     * So, double-counting is effectively avoided.
2475     */
2476    __mem_cgroup_commit_charge(mem, pc, ctype);
2477
2478    /*
2479     * Both of oldpage and newpage are still under lock_page().
2480     * Then, we don't have to care about race in radix-tree.
2481     * But we have to be careful that this page is unmapped or not.
2482     *
2483     * There is a case for !page_mapped(). At the start of
2484     * migration, oldpage was mapped. But now, it's zapped.
2485     * But we know *target* page is not freed/reused under us.
2486     * mem_cgroup_uncharge_page() does all necessary checks.
2487     */
2488    if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
2489        mem_cgroup_uncharge_page(target);
2490    /*
2491     * At migration, we may charge account against cgroup which has no tasks
2492     * So, rmdir()->pre_destroy() can be called while we do this charge.
2493     * In that case, we need to call pre_destroy() again. check it here.
2494     */
2495    cgroup_release_and_wakeup_rmdir(&mem->css);
2496}
2497
2498/*
2499 * A call to try to shrink memory usage on charge failure at shmem's swapin.
2500 * Calling hierarchical_reclaim is not enough because we should update
2501 * last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM.
2502 * Moreover considering hierarchy, we should reclaim from the mem_over_limit,
2503 * not from the memcg which this page would be charged to.
2504 * try_charge_swapin does all of these works properly.
2505 */
2506int mem_cgroup_shmem_charge_fallback(struct page *page,
2507                struct mm_struct *mm,
2508                gfp_t gfp_mask)
2509{
2510    struct mem_cgroup *mem = NULL;
2511    int ret;
2512
2513    if (mem_cgroup_disabled())
2514        return 0;
2515
2516    ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2517    if (!ret)
2518        mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */
2519
2520    return ret;
2521}
2522
2523static DEFINE_MUTEX(set_limit_mutex);
2524
2525static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
2526                unsigned long long val)
2527{
2528    int retry_count;
2529    u64 memswlimit;
2530    int ret = 0;
2531    int children = mem_cgroup_count_children(memcg);
2532    u64 curusage, oldusage;
2533
2534    /*
2535     * For keeping hierarchical_reclaim simple, how long we should retry
2536     * is depends on callers. We set our retry-count to be function
2537     * of # of children which we should visit in this loop.
2538     */
2539    retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
2540
2541    oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
2542
2543    while (retry_count) {
2544        if (signal_pending(current)) {
2545            ret = -EINTR;
2546            break;
2547        }
2548        /*
2549         * Rather than hide all in some function, I do this in
2550         * open coded manner. You see what this really does.
2551         * We have to guarantee mem->res.limit < mem->memsw.limit.
2552         */
2553        mutex_lock(&set_limit_mutex);
2554        memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
2555        if (memswlimit < val) {
2556            ret = -EINVAL;
2557            mutex_unlock(&set_limit_mutex);
2558            break;
2559        }
2560        ret = res_counter_set_limit(&memcg->res, val);
2561        if (!ret) {
2562            if (memswlimit == val)
2563                memcg->memsw_is_minimum = true;
2564            else
2565                memcg->memsw_is_minimum = false;
2566        }
2567        mutex_unlock(&set_limit_mutex);
2568
2569        if (!ret)
2570            break;
2571
2572        mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
2573                        MEM_CGROUP_RECLAIM_SHRINK);
2574        curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
2575        /* Usage is reduced ? */
2576          if (curusage >= oldusage)
2577            retry_count--;
2578        else
2579            oldusage = curusage;
2580    }
2581
2582    return ret;
2583}
2584
2585static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
2586                    unsigned long long val)
2587{
2588    int retry_count;
2589    u64 memlimit, oldusage, curusage;
2590    int children = mem_cgroup_count_children(memcg);
2591    int ret = -EBUSY;
2592
2593    /* see mem_cgroup_resize_res_limit */
2594     retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
2595    oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
2596    while (retry_count) {
2597        if (signal_pending(current)) {
2598            ret = -EINTR;
2599            break;
2600        }
2601        /*
2602         * Rather than hide all in some function, I do this in
2603         * open coded manner. You see what this really does.
2604         * We have to guarantee mem->res.limit < mem->memsw.limit.
2605         */
2606        mutex_lock(&set_limit_mutex);
2607        memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
2608        if (memlimit > val) {
2609            ret = -EINVAL;
2610            mutex_unlock(&set_limit_mutex);
2611            break;
2612        }
2613        ret = res_counter_set_limit(&memcg->memsw, val);
2614        if (!ret) {
2615            if (memlimit == val)
2616                memcg->memsw_is_minimum = true;
2617            else
2618                memcg->memsw_is_minimum = false;
2619        }
2620        mutex_unlock(&set_limit_mutex);
2621
2622        if (!ret)
2623            break;
2624
2625        mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
2626                        MEM_CGROUP_RECLAIM_NOSWAP |
2627                        MEM_CGROUP_RECLAIM_SHRINK);
2628        curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
2629        /* Usage is reduced ? */
2630        if (curusage >= oldusage)
2631            retry_count--;
2632        else
2633            oldusage = curusage;
2634    }
2635    return ret;
2636}
2637
2638unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
2639                        gfp_t gfp_mask, int nid,
2640                        int zid)
2641{
2642    unsigned long nr_reclaimed = 0;
2643    struct mem_cgroup_per_zone *mz, *next_mz = NULL;
2644    unsigned long reclaimed;
2645    int loop = 0;
2646    struct mem_cgroup_tree_per_zone *mctz;
2647    unsigned long long excess;
2648
2649    if (order > 0)
2650        return 0;
2651
2652    mctz = soft_limit_tree_node_zone(nid, zid);
2653    /*
2654     * This loop can run a while, specially if mem_cgroup's continuously
2655     * keep exceeding their soft limit and putting the system under
2656     * pressure
2657     */
2658    do {
2659        if (next_mz)
2660            mz = next_mz;
2661        else
2662            mz = mem_cgroup_largest_soft_limit_node(mctz);
2663        if (!mz)
2664            break;
2665
2666        reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
2667                        gfp_mask,
2668                        MEM_CGROUP_RECLAIM_SOFT);
2669        nr_reclaimed += reclaimed;
2670        spin_lock(&mctz->lock);
2671
2672        /*
2673         * If we failed to reclaim anything from this memory cgroup
2674         * it is time to move on to the next cgroup
2675         */
2676        next_mz = NULL;
2677        if (!reclaimed) {
2678            do {
2679                /*
2680                 * Loop until we find yet another one.
2681                 *
2682                 * By the time we get the soft_limit lock
2683                 * again, someone might have aded the
2684                 * group back on the RB tree. Iterate to
2685                 * make sure we get a different mem.
2686                 * mem_cgroup_largest_soft_limit_node returns
2687                 * NULL if no other cgroup is present on
2688                 * the tree
2689                 */
2690                next_mz =
2691                __mem_cgroup_largest_soft_limit_node(mctz);
2692                if (next_mz == mz) {
2693                    css_put(&next_mz->mem->css);
2694                    next_mz = NULL;
2695                } else /* next_mz == NULL or other memcg */
2696                    break;
2697            } while (1);
2698        }
2699        __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
2700        excess = res_counter_soft_limit_excess(&mz->mem->res);
2701        /*
2702         * One school of thought says that we should not add
2703         * back the node to the tree if reclaim returns 0.
2704         * But our reclaim could return 0, simply because due
2705         * to priority we are exposing a smaller subset of
2706         * memory to reclaim from. Consider this as a longer
2707         * term TODO.
2708         */
2709        /* If excess == 0, no tree ops */
2710        __mem_cgroup_insert_exceeded(mz->mem, mz, mctz, excess);
2711        spin_unlock(&mctz->lock);
2712        css_put(&mz->mem->css);
2713        loop++;
2714        /*
2715         * Could not reclaim anything and there are no more
2716         * mem cgroups to try or we seem to be looping without
2717         * reclaiming anything.
2718         */
2719        if (!nr_reclaimed &&
2720            (next_mz == NULL ||
2721            loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
2722            break;
2723    } while (!nr_reclaimed);
2724    if (next_mz)
2725        css_put(&next_mz->mem->css);
2726    return nr_reclaimed;
2727}
2728
2729/*
2730 * This routine traverse page_cgroup in given list and drop them all.
2731 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
2732 */
2733static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
2734                int node, int zid, enum lru_list lru)
2735{
2736    struct zone *zone;
2737    struct mem_cgroup_per_zone *mz;
2738    struct page_cgroup *pc, *busy;
2739    unsigned long flags, loop;
2740    struct list_head *list;
2741    int ret = 0;
2742
2743    zone = &NODE_DATA(node)->node_zones[zid];
2744    mz = mem_cgroup_zoneinfo(mem, node, zid);
2745    list = &mz->lists[lru];
2746
2747    loop = MEM_CGROUP_ZSTAT(mz, lru);
2748    /* give some margin against EBUSY etc...*/
2749    loop += 256;
2750    busy = NULL;
2751    while (loop--) {
2752        ret = 0;
2753        spin_lock_irqsave(&zone->lru_lock, flags);
2754        if (list_empty(list)) {
2755            spin_unlock_irqrestore(&zone->lru_lock, flags);
2756            break;
2757        }
2758        pc = list_entry(list->prev, struct page_cgroup, lru);
2759        if (busy == pc) {
2760            list_move(&pc->lru, list);
2761            busy = NULL;
2762            spin_unlock_irqrestore(&zone->lru_lock, flags);
2763            continue;
2764        }
2765        spin_unlock_irqrestore(&zone->lru_lock, flags);
2766
2767        ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
2768        if (ret == -ENOMEM)
2769            break;
2770
2771        if (ret == -EBUSY || ret == -EINVAL) {
2772            /* found lock contention or "pc" is obsolete. */
2773            busy = pc;
2774            cond_resched();
2775        } else
2776            busy = NULL;
2777    }
2778
2779    if (!ret && !list_empty(list))
2780        return -EBUSY;
2781    return ret;
2782}
2783
2784/*
2785 * make mem_cgroup's charge to be 0 if there is no task.
2786 * This enables deleting this mem_cgroup.
2787 */
2788static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
2789{
2790    int ret;
2791    int node, zid, shrink;
2792    int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
2793    struct cgroup *cgrp = mem->css.cgroup;
2794
2795    css_get(&mem->css);
2796
2797    shrink = 0;
2798    /* should free all ? */
2799    if (free_all)
2800        goto try_to_free;
2801move_account:
2802    do {
2803        ret = -EBUSY;
2804        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
2805            goto out;
2806        ret = -EINTR;
2807        if (signal_pending(current))
2808            goto out;
2809        /* This is for making all *used* pages to be on LRU. */
2810        lru_add_drain_all();
2811        drain_all_stock_sync();
2812        ret = 0;
2813        for_each_node_state(node, N_HIGH_MEMORY) {
2814            for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
2815                enum lru_list l;
2816                for_each_lru(l) {
2817                    ret = mem_cgroup_force_empty_list(mem,
2818                            node, zid, l);
2819                    if (ret)
2820                        break;
2821                }
2822            }
2823            if (ret)
2824                break;
2825        }
2826        /* it seems parent cgroup doesn't have enough mem */
2827        if (ret == -ENOMEM)
2828            goto try_to_free;
2829        cond_resched();
2830    /* "ret" should also be checked to ensure all lists are empty. */
2831    } while (mem->res.usage > 0 || ret);
2832out:
2833    css_put(&mem->css);
2834    return ret;
2835
2836try_to_free:
2837    /* returns EBUSY if there is a task or if we come here twice. */
2838    if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
2839        ret = -EBUSY;
2840        goto out;
2841    }
2842    /* we call try-to-free pages for make this cgroup empty */
2843    lru_add_drain_all();
2844    /* try to free all pages in this cgroup */
2845    shrink = 1;
2846    while (nr_retries && mem->res.usage > 0) {
2847        int progress;
2848
2849        if (signal_pending(current)) {
2850            ret = -EINTR;
2851            goto out;
2852        }
2853        progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
2854                        false, get_swappiness(mem));
2855        if (!progress) {
2856            nr_retries--;
2857            /* maybe some writeback is necessary */
2858            congestion_wait(BLK_RW_ASYNC, HZ/10);
2859        }
2860
2861    }
2862    lru_add_drain();
2863    /* try move_account...there may be some *locked* pages. */
2864    goto move_account;
2865}
2866
2867int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
2868{
2869    return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
2870}
2871
2872
2873static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
2874{
2875    return mem_cgroup_from_cont(cont)->use_hierarchy;
2876}
2877
2878static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
2879                    u64 val)
2880{
2881    int retval = 0;
2882    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
2883    struct cgroup *parent = cont->parent;
2884    struct mem_cgroup *parent_mem = NULL;
2885
2886    if (parent)
2887        parent_mem = mem_cgroup_from_cont(parent);
2888
2889    cgroup_lock();
2890    /*
2891     * If parent's use_hierarchy is set, we can't make any modifications
2892     * in the child subtrees. If it is unset, then the change can
2893     * occur, provided the current cgroup has no children.
2894     *
2895     * For the root cgroup, parent_mem is NULL, we allow value to be
2896     * set if there are no children.
2897     */
2898    if ((!parent_mem || !parent_mem->use_hierarchy) &&
2899                (val == 1 || val == 0)) {
2900        if (list_empty(&cont->children))
2901            mem->use_hierarchy = val;
2902        else
2903            retval = -EBUSY;
2904    } else
2905        retval = -EINVAL;
2906    cgroup_unlock();
2907
2908    return retval;
2909}
2910
2911struct mem_cgroup_idx_data {
2912    s64 val;
2913    enum mem_cgroup_stat_index idx;
2914};
2915
2916static int
2917mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data)
2918{
2919    struct mem_cgroup_idx_data *d = data;
2920    d->val += mem_cgroup_read_stat(mem, d->idx);
2921    return 0;
2922}
2923
2924static void
2925mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
2926                enum mem_cgroup_stat_index idx, s64 *val)
2927{
2928    struct mem_cgroup_idx_data d;
2929    d.idx = idx;
2930    d.val = 0;
2931    mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat);
2932    *val = d.val;
2933}
2934
2935static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
2936{
2937    u64 idx_val, val;
2938
2939    if (!mem_cgroup_is_root(mem)) {
2940        if (!swap)
2941            return res_counter_read_u64(&mem->res, RES_USAGE);
2942        else
2943            return res_counter_read_u64(&mem->memsw, RES_USAGE);
2944    }
2945
2946    mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE, &idx_val);
2947    val = idx_val;
2948    mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS, &idx_val);
2949    val += idx_val;
2950
2951    if (swap) {
2952        mem_cgroup_get_recursive_idx_stat(mem,
2953                MEM_CGROUP_STAT_SWAPOUT, &idx_val);
2954        val += idx_val;
2955    }
2956
2957    return val << PAGE_SHIFT;
2958}
2959
2960static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
2961{
2962    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
2963    u64 val;
2964    int type, name;
2965
2966    type = MEMFILE_TYPE(cft->private);
2967    name = MEMFILE_ATTR(cft->private);
2968    switch (type) {
2969    case _MEM:
2970        if (name == RES_USAGE)
2971            val = mem_cgroup_usage(mem, false);
2972        else
2973            val = res_counter_read_u64(&mem->res, name);
2974        break;
2975    case _MEMSWAP:
2976        if (name == RES_USAGE)
2977            val = mem_cgroup_usage(mem, true);
2978        else
2979            val = res_counter_read_u64(&mem->memsw, name);
2980        break;
2981    default:
2982        BUG();
2983        break;
2984    }
2985    return val;
2986}
2987/*
2988 * The user of this function is...
2989 * RES_LIMIT.
2990 */
2991static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
2992                const char *buffer)
2993{
2994    struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
2995    int type, name;
2996    unsigned long long val;
2997    int ret;
2998
2999    type = MEMFILE_TYPE(cft->private);
3000    name = MEMFILE_ATTR(cft->private);
3001    switch (name) {
3002    case RES_LIMIT:
3003        if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3004            ret = -EINVAL;
3005            break;
3006        }
3007        /* This function does all necessary parse...reuse it */
3008        ret = res_counter_memparse_write_strategy(buffer, &val);
3009        if (ret)
3010            break;
3011        if (type == _MEM)
3012            ret = mem_cgroup_resize_limit(memcg, val);
3013        else
3014            ret = mem_cgroup_resize_memsw_limit(memcg, val);
3015        break;
3016    case RES_SOFT_LIMIT:
3017        ret = res_counter_memparse_write_strategy(buffer, &val);
3018        if (ret)
3019            break;
3020        /*
3021         * For memsw, soft limits are hard to implement in terms
3022         * of semantics, for now, we support soft limits for
3023         * control without swap
3024         */
3025        if (type == _MEM)
3026            ret = res_counter_set_soft_limit(&memcg->res, val);
3027        else
3028            ret = -EINVAL;
3029        break;
3030    default:
3031        ret = -EINVAL; /* should be BUG() ? */
3032        break;
3033    }
3034    return ret;
3035}
3036
3037static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
3038        unsigned long long *mem_limit, unsigned long long *memsw_limit)
3039{
3040    struct cgroup *cgroup;
3041    unsigned long long min_limit, min_memsw_limit, tmp;
3042
3043    min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3044    min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3045    cgroup = memcg->css.cgroup;
3046    if (!memcg->use_hierarchy)
3047        goto out;
3048
3049    while (cgroup->parent) {
3050        cgroup = cgroup->parent;
3051        memcg = mem_cgroup_from_cont(cgroup);
3052        if (!memcg->use_hierarchy)
3053            break;
3054        tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
3055        min_limit = min(min_limit, tmp);
3056        tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3057        min_memsw_limit = min(min_memsw_limit, tmp);
3058    }
3059out:
3060    *mem_limit = min_limit;
3061    *memsw_limit = min_memsw_limit;
3062    return;
3063}
3064
3065static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
3066{
3067    struct mem_cgroup *mem;
3068    int type, name;
3069
3070    mem = mem_cgroup_from_cont(cont);
3071    type = MEMFILE_TYPE(event);
3072    name = MEMFILE_ATTR(event);
3073    switch (name) {
3074    case RES_MAX_USAGE:
3075        if (type == _MEM)
3076            res_counter_reset_max(&mem->res);
3077        else
3078            res_counter_reset_max(&mem->memsw);
3079        break;
3080    case RES_FAILCNT:
3081        if (type == _MEM)
3082            res_counter_reset_failcnt(&mem->res);
3083        else
3084            res_counter_reset_failcnt(&mem->memsw);
3085        break;
3086    }
3087
3088    return 0;
3089}
3090
3091static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
3092                    struct cftype *cft)
3093{
3094    return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
3095}
3096
3097#ifdef CONFIG_MMU
3098static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3099                    struct cftype *cft, u64 val)
3100{
3101    struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3102
3103    if (val >= (1 << NR_MOVE_TYPE))
3104        return -EINVAL;
3105    /*
3106     * We check this value several times in both in can_attach() and
3107     * attach(), so we need cgroup lock to prevent this value from being
3108     * inconsistent.
3109     */
3110    cgroup_lock();
3111    mem->move_charge_at_immigrate = val;
3112    cgroup_unlock();
3113
3114    return 0;
3115}
3116#else
3117static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3118                    struct cftype *cft, u64 val)
3119{
3120    return -ENOSYS;
3121}
3122#endif
3123
3124
3125/* For read statistics */
3126enum {
3127    MCS_CACHE,
3128    MCS_RSS,
3129    MCS_FILE_MAPPED,
3130    MCS_PGPGIN,
3131    MCS_PGPGOUT,
3132    MCS_SWAP,
3133    MCS_INACTIVE_ANON,
3134    MCS_ACTIVE_ANON,
3135    MCS_INACTIVE_FILE,
3136    MCS_ACTIVE_FILE,
3137    MCS_UNEVICTABLE,
3138    NR_MCS_STAT,
3139};
3140
3141struct mcs_total_stat {
3142    s64 stat[NR_MCS_STAT];
3143};
3144
3145struct {
3146    char *local_name;
3147    char *total_name;
3148} memcg_stat_strings[NR_MCS_STAT] = {
3149    {"cache", "total_cache"},
3150    {"rss", "total_rss"},
3151    {"mapped_file", "total_mapped_file"},
3152    {"pgpgin", "total_pgpgin"},
3153    {"pgpgout", "total_pgpgout"},
3154    {"swap", "total_swap"},
3155    {"inactive_anon", "total_inactive_anon"},
3156    {"active_anon", "total_active_anon"},
3157    {"inactive_file", "total_inactive_file"},
3158    {"active_file", "total_active_file"},
3159    {"unevictable", "total_unevictable"}
3160};
3161
3162
3163static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
3164{
3165    struct mcs_total_stat *s = data;
3166    s64 val;
3167
3168    /* per cpu stat */
3169    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
3170    s->stat[MCS_CACHE] += val * PAGE_SIZE;
3171    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
3172    s->stat[MCS_RSS] += val * PAGE_SIZE;
3173    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_MAPPED);
3174    s->stat[MCS_FILE_MAPPED] += val * PAGE_SIZE;
3175    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGIN_COUNT);
3176    s->stat[MCS_PGPGIN] += val;
3177    val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGOUT_COUNT);
3178    s->stat[MCS_PGPGOUT] += val;
3179    if (do_swap_account) {
3180        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
3181        s->stat[MCS_SWAP] += val * PAGE_SIZE;
3182    }
3183
3184    /* per zone stat */
3185    val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
3186    s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
3187    val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_ANON);
3188    s->stat[MCS_ACTIVE_ANON] += val * PAGE_SIZE;
3189    val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_FILE);
3190    s->stat[MCS_INACTIVE_FILE] += val * PAGE_SIZE;
3191    val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_FILE);
3192    s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE;
3193    val = mem_cgroup_get_local_zonestat(mem, LRU_UNEVICTABLE);
3194    s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE;
3195    return 0;
3196}
3197
3198static void
3199mem_cgroup_get_total_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
3200{
3201    mem_cgroup_walk_tree(mem, s, mem_cgroup_get_local_stat);
3202}
3203
3204static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
3205                 struct cgroup_map_cb *cb)
3206{
3207    struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
3208    struct mcs_total_stat mystat;
3209    int i;
3210
3211    memset(&mystat, 0, sizeof(mystat));
3212    mem_cgroup_get_local_stat(mem_cont, &mystat);
3213
3214    for (i = 0; i < NR_MCS_STAT; i++) {
3215        if (i == MCS_SWAP && !do_swap_account)
3216            continue;
3217        cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]);
3218    }
3219
3220    /* Hierarchical information */
3221    {
3222        unsigned long long limit, memsw_limit;
3223        memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
3224        cb->fill(cb, "hierarchical_memory_limit", limit);
3225        if (do_swap_account)
3226            cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
3227    }
3228
3229    memset(&mystat, 0, sizeof(mystat));
3230    mem_cgroup_get_total_stat(mem_cont, &mystat);
3231    for (i = 0; i < NR_MCS_STAT; i++) {
3232        if (i == MCS_SWAP && !do_swap_account)
3233            continue;
3234        cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]);
3235    }
3236
3237#ifdef CONFIG_DEBUG_VM
3238    cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
3239
3240    {
3241        int nid, zid;
3242        struct mem_cgroup_per_zone *mz;
3243        unsigned long recent_rotated[2] = {0, 0};
3244        unsigned long recent_scanned[2] = {0, 0};
3245
3246        for_each_online_node(nid)
3247            for (zid = 0; zid < MAX_NR_ZONES; zid++) {
3248                mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
3249
3250                recent_rotated[0] +=
3251                    mz->reclaim_stat.recent_rotated[0];
3252                recent_rotated[1] +=
3253                    mz->reclaim_stat.recent_rotated[1];
3254                recent_scanned[0] +=
3255                    mz->reclaim_stat.recent_scanned[0];
3256                recent_scanned[1] +=
3257                    mz->reclaim_stat.recent_scanned[1];
3258            }
3259        cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
3260        cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
3261        cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
3262        cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
3263    }
3264#endif
3265
3266    return 0;
3267}
3268
3269static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
3270{
3271    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3272
3273    return get_swappiness(memcg);
3274}
3275
3276static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
3277                       u64 val)
3278{
3279    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3280    struct mem_cgroup *parent;
3281
3282    if (val > 100)
3283        return -EINVAL;
3284
3285    if (cgrp->parent == NULL)
3286        return -EINVAL;
3287
3288    parent = mem_cgroup_from_cont(cgrp->parent);
3289
3290    cgroup_lock();
3291
3292    /* If under hierarchy, only empty-root can set this value */
3293    if ((parent->use_hierarchy) ||
3294        (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
3295        cgroup_unlock();
3296        return -EINVAL;
3297    }
3298
3299    spin_lock(&memcg->reclaim_param_lock);
3300    memcg->swappiness = val;
3301    spin_unlock(&memcg->reclaim_param_lock);
3302
3303    cgroup_unlock();
3304
3305    return 0;
3306}
3307
3308static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
3309{
3310    struct mem_cgroup_threshold_ary *t;
3311    u64 usage;
3312    int i;
3313
3314    rcu_read_lock();
3315    if (!swap)
3316        t = rcu_dereference(memcg->thresholds);
3317    else
3318        t = rcu_dereference(memcg->memsw_thresholds);
3319
3320    if (!t)
3321        goto unlock;
3322
3323    usage = mem_cgroup_usage(memcg, swap);
3324
3325    /*
3326     * current_threshold points to threshold just below usage.
3327     * If it's not true, a threshold was crossed after last
3328     * call of __mem_cgroup_threshold().
3329     */
3330    i = atomic_read(&t->current_threshold);
3331
3332    /*
3333     * Iterate backward over array of thresholds starting from
3334     * current_threshold and check if a threshold is crossed.
3335     * If none of thresholds below usage is crossed, we read
3336     * only one element of the array here.
3337     */
3338    for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
3339        eventfd_signal(t->entries[i].eventfd, 1);
3340
3341    /* i = current_threshold + 1 */
3342    i++;
3343
3344    /*
3345     * Iterate forward over array of thresholds starting from
3346     * current_threshold+1 and check if a threshold is crossed.
3347     * If none of thresholds above usage is crossed, we read
3348     * only one element of the array here.
3349     */
3350    for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
3351        eventfd_signal(t->entries[i].eventfd, 1);
3352
3353    /* Update current_threshold */
3354    atomic_set(&t->current_threshold, i - 1);
3355unlock:
3356    rcu_read_unlock();
3357}
3358
3359static void mem_cgroup_threshold(struct mem_cgroup *memcg)
3360{
3361    __mem_cgroup_threshold(memcg, false);
3362    if (do_swap_account)
3363        __mem_cgroup_threshold(memcg, true);
3364}
3365
3366static int compare_thresholds(const void *a, const void *b)
3367{
3368    const struct mem_cgroup_threshold *_a = a;
3369    const struct mem_cgroup_threshold *_b = b;
3370
3371    return _a->threshold - _b->threshold;
3372}
3373
3374static int mem_cgroup_register_event(struct cgroup *cgrp, struct cftype *cft,
3375        struct eventfd_ctx *eventfd, const char *args)
3376{
3377    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3378    struct mem_cgroup_threshold_ary *thresholds, *thresholds_new;
3379    int type = MEMFILE_TYPE(cft->private);
3380    u64 threshold, usage;
3381    int size;
3382    int i, ret;
3383
3384    ret = res_counter_memparse_write_strategy(args, &threshold);
3385    if (ret)
3386        return ret;
3387
3388    mutex_lock(&memcg->thresholds_lock);
3389    if (type == _MEM)
3390        thresholds = memcg->thresholds;
3391    else if (type == _MEMSWAP)
3392        thresholds = memcg->memsw_thresholds;
3393    else
3394        BUG();
3395
3396    usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3397
3398    /* Check if a threshold crossed before adding a new one */
3399    if (thresholds)
3400        __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3401
3402    if (thresholds)
3403        size = thresholds->size + 1;
3404    else
3405        size = 1;
3406
3407    /* Allocate memory for new array of thresholds */
3408    thresholds_new = kmalloc(sizeof(*thresholds_new) +
3409            size * sizeof(struct mem_cgroup_threshold),
3410            GFP_KERNEL);
3411    if (!thresholds_new) {
3412        ret = -ENOMEM;
3413        goto unlock;
3414    }
3415    thresholds_new->size = size;
3416
3417    /* Copy thresholds (if any) to new array */
3418    if (thresholds)
3419        memcpy(thresholds_new->entries, thresholds->entries,
3420                thresholds->size *
3421                sizeof(struct mem_cgroup_threshold));
3422    /* Add new threshold */
3423    thresholds_new->entries[size - 1].eventfd = eventfd;
3424    thresholds_new->entries[size - 1].threshold = threshold;
3425
3426    /* Sort thresholds. Registering of new threshold isn't time-critical */
3427    sort(thresholds_new->entries, size,
3428            sizeof(struct mem_cgroup_threshold),
3429            compare_thresholds, NULL);
3430
3431    /* Find current threshold */
3432    atomic_set(&thresholds_new->current_threshold, -1);
3433    for (i = 0; i < size; i++) {
3434        if (thresholds_new->entries[i].threshold < usage) {
3435            /*
3436             * thresholds_new->current_threshold will not be used
3437             * until rcu_assign_pointer(), so it's safe to increment
3438             * it here.
3439             */
3440            atomic_inc(&thresholds_new->current_threshold);
3441        }
3442    }
3443
3444    if (type == _MEM)
3445        rcu_assign_pointer(memcg->thresholds, thresholds_new);
3446    else
3447        rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new);
3448
3449    /* To be sure that nobody uses thresholds before freeing it */
3450    synchronize_rcu();
3451
3452    kfree(thresholds);
3453unlock:
3454    mutex_unlock(&memcg->thresholds_lock);
3455
3456    return ret;
3457}
3458
3459static int mem_cgroup_unregister_event(struct cgroup *cgrp, struct cftype *cft,
3460        struct eventfd_ctx *eventfd)
3461{
3462    struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3463    struct mem_cgroup_threshold_ary *thresholds, *thresholds_new;
3464    int type = MEMFILE_TYPE(cft->private);
3465    u64 usage;
3466    int size = 0;
3467    int i, j, ret;
3468
3469    mutex_lock(&memcg->thresholds_lock);
3470    if (type == _MEM)
3471        thresholds = memcg->thresholds;
3472    else if (type == _MEMSWAP)
3473        thresholds = memcg->memsw_thresholds;
3474    else
3475        BUG();
3476
3477    /*
3478     * Something went wrong if we trying to unregister a threshold
3479     * if we don't have thresholds
3480     */
3481    BUG_ON(!thresholds);
3482
3483    usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3484
3485    /* Check if a threshold crossed before removing */
3486    __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3487
3488    /* Calculate new number of threshold */
3489    for (i = 0; i < thresholds->size; i++) {
3490        if (thresholds->entries[i].eventfd != eventfd)
3491            size++;
3492    }
3493
3494    /* Set thresholds array to NULL if we don't have thresholds */
3495    if (!size) {
3496        thresholds_new = NULL;
3497        goto assign;
3498    }
3499
3500    /* Allocate memory for new array of thresholds */
3501    thresholds_new = kmalloc(sizeof(*thresholds_new) +
3502            size * sizeof(struct mem_cgroup_threshold),
3503            GFP_KERNEL);
3504    if (!thresholds_new) {
3505        ret = -ENOMEM;
3506        goto unlock;
3507    }
3508    thresholds_new->size = size;
3509
3510    /* Copy thresholds and find current threshold */
3511    atomic_set(&thresholds_new->current_threshold, -1);
3512    for (i = 0, j = 0; i < thresholds->size; i++) {
3513        if (thresholds->entries[i].eventfd == eventfd)
3514            continue;
3515
3516        thresholds_new->entries[j] = thresholds->entries[i];
3517        if (thresholds_new->entries[j].threshold < usage) {
3518            /*
3519             * thresholds_new->current_threshold will not be used
3520             * until rcu_assign_pointer(), so it's safe to increment
3521             * it here.
3522             */
3523            atomic_inc(&thresholds_new->current_threshold);
3524        }
3525        j++;
3526    }
3527
3528assign:
3529    if (type == _MEM)
3530        rcu_assign_pointer(memcg->thresholds, thresholds_new);
3531    else
3532        rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new);
3533
3534    /* To be sure that nobody uses thresholds before freeing it */
3535    synchronize_rcu();
3536
3537    kfree(thresholds);
3538unlock:
3539    mutex_unlock(&memcg->thresholds_lock);
3540
3541    return ret;
3542}
3543
3544static struct cftype mem_cgroup_files[] = {
3545    {
3546        .name = "usage_in_bytes",
3547        .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
3548        .read_u64 = mem_cgroup_read,
3549        .register_event = mem_cgroup_register_event,
3550        .unregister_event = mem_cgroup_unregister_event,
3551    },
3552    {
3553        .name = "max_usage_in_bytes",
3554        .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
3555        .trigger = mem_cgroup_reset,
3556        .read_u64 = mem_cgroup_read,
3557    },
3558    {
3559        .name = "limit_in_bytes",
3560        .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
3561        .write_string = mem_cgroup_write,
3562        .read_u64 = mem_cgroup_read,
3563    },
3564    {
3565        .name = "soft_limit_in_bytes",
3566        .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
3567        .write_string = mem_cgroup_write,
3568        .read_u64 = mem_cgroup_read,
3569    },
3570    {
3571        .name = "failcnt",
3572        .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
3573        .trigger = mem_cgroup_reset,
3574        .read_u64 = mem_cgroup_read,
3575    },
3576    {
3577        .name = "stat",
3578        .read_map = mem_control_stat_show,
3579    },
3580    {
3581        .name = "force_empty",
3582        .trigger = mem_cgroup_force_empty_write,
3583    },
3584    {
3585        .name = "use_hierarchy",
3586        .write_u64 = mem_cgroup_hierarchy_write,
3587        .read_u64 = mem_cgroup_hierarchy_read,
3588    },
3589    {
3590        .name = "swappiness",
3591        .read_u64 = mem_cgroup_swappiness_read,
3592        .write_u64 = mem_cgroup_swappiness_write,
3593    },
3594    {
3595        .name = "move_charge_at_immigrate",
3596        .read_u64 = mem_cgroup_move_charge_read,
3597        .write_u64 = mem_cgroup_move_charge_write,
3598    },
3599};
3600
3601#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
3602static struct cftype memsw_cgroup_files[] = {
3603    {
3604        .name = "memsw.usage_in_bytes",
3605        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
3606        .read_u64 = mem_cgroup_read,
3607        .register_event = mem_cgroup_register_event,
3608        .unregister_event = mem_cgroup_unregister_event,
3609    },
3610    {
3611        .name = "memsw.max_usage_in_bytes",
3612        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
3613        .trigger = mem_cgroup_reset,
3614        .read_u64 = mem_cgroup_read,
3615    },
3616    {
3617        .name = "memsw.limit_in_bytes",
3618        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
3619        .write_string = mem_cgroup_write,
3620        .read_u64 = mem_cgroup_read,
3621    },
3622    {
3623        .name = "memsw.failcnt",
3624        .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
3625        .trigger = mem_cgroup_reset,
3626        .read_u64 = mem_cgroup_read,
3627    },
3628};
3629
3630static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
3631{
3632    if (!do_swap_account)
3633        return 0;
3634    return cgroup_add_files(cont, ss, memsw_cgroup_files,
3635                ARRAY_SIZE(memsw_cgroup_files));
3636};
3637#else
3638static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
3639{
3640    return 0;
3641}
3642#endif
3643
3644static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
3645{
3646    struct mem_cgroup_per_node *pn;
3647    struct mem_cgroup_per_zone *mz;
3648    enum lru_list l;
3649    int zone, tmp = node;
3650    /*
3651     * This routine is called against possible nodes.
3652     * But it's BUG to call kmalloc() against offline node.
3653     *
3654     * TODO: this routine can waste much memory for nodes which will
3655     * never be onlined. It's better to use memory hotplug callback
3656     * function.
3657     */
3658    if (!node_state(node, N_NORMAL_MEMORY))
3659        tmp = -1;
3660    pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
3661    if (!pn)
3662        return 1;
3663
3664    mem->info.nodeinfo[node] = pn;
3665    memset(pn, 0, sizeof(*pn));
3666
3667    for (zone = 0; zone < MAX_NR_ZONES; zone++) {
3668        mz = &pn->zoneinfo[zone];
3669        for_each_lru(l)
3670            INIT_LIST_HEAD(&mz->lists[l]);
3671        mz->usage_in_excess = 0;
3672        mz->on_tree = false;
3673        mz->mem = mem;
3674    }
3675    return 0;
3676}
3677
3678static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
3679{
3680    kfree(mem->info.nodeinfo[node]);
3681}
3682
3683static struct mem_cgroup *mem_cgroup_alloc(void)
3684{
3685    struct mem_cgroup *mem;
3686    int size = sizeof(struct mem_cgroup);
3687
3688    /* Can be very big if MAX_NUMNODES is very big */
3689    if (size < PAGE_SIZE)
3690        mem = kmalloc(size, GFP_KERNEL);
3691    else
3692        mem = vmalloc(size);
3693
3694    if (!mem)
3695        return NULL;
3696
3697    memset(mem, 0, size);
3698    mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
3699    if (!mem->stat) {
3700        if (size < PAGE_SIZE)
3701            kfree(mem);
3702        else
3703            vfree(mem);
3704        mem = NULL;
3705    }
3706    return mem;
3707}
3708
3709/*
3710 * At destroying mem_cgroup, references from swap_cgroup can remain.
3711 * (scanning all at force_empty is too costly...)
3712 *
3713 * Instead of clearing all references at force_empty, we remember
3714 * the number of reference from swap_cgroup and free mem_cgroup when
3715 * it goes down to 0.
3716 *
3717 * Removal of cgroup itself succeeds regardless of refs from swap.
3718 */
3719
3720static void __mem_cgroup_free(struct mem_cgroup *mem)
3721{
3722    int node;
3723
3724    mem_cgroup_remove_from_trees(mem);
3725    free_css_id(&mem_cgroup_subsys, &mem->css);
3726
3727    for_each_node_state(node, N_POSSIBLE)
3728        free_mem_cgroup_per_zone_info(mem, node);
3729
3730    free_percpu(mem->stat);
3731    if (sizeof(struct mem_cgroup) < PAGE_SIZE)
3732        kfree(mem);
3733    else
3734        vfree(mem);
3735}
3736
3737static void mem_cgroup_get(struct mem_cgroup *mem)
3738{
3739    atomic_inc(&mem->refcnt);
3740}
3741
3742static void __mem_cgroup_put(struct mem_cgroup *mem, int count)
3743{
3744    if (atomic_sub_and_test(count, &mem->refcnt)) {
3745        struct mem_cgroup *parent = parent_mem_cgroup(mem);
3746        __mem_cgroup_free(mem);
3747        if (parent)
3748            mem_cgroup_put(parent);
3749    }
3750}
3751
3752static void mem_cgroup_put(struct mem_cgroup *mem)
3753{
3754    __mem_cgroup_put(mem, 1);
3755}
3756
3757/*
3758 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
3759 */
3760static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem)
3761{
3762    if (!mem->res.parent)
3763        return NULL;
3764    return mem_cgroup_from_res_counter(mem->res.parent, res);
3765}
3766
3767#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
3768static void __init enable_swap_cgroup(void)
3769{
3770    if (!mem_cgroup_disabled() && really_do_swap_account)
3771        do_swap_account = 1;
3772}
3773#else
3774static void __init enable_swap_cgroup(void)
3775{
3776}
3777#endif
3778
3779static int mem_cgroup_soft_limit_tree_init(void)
3780{
3781    struct mem_cgroup_tree_per_node *rtpn;
3782    struct mem_cgroup_tree_per_zone *rtpz;
3783    int tmp, node, zone;
3784
3785    for_each_node_state(node, N_POSSIBLE) {
3786        tmp = node;
3787        if (!node_state(node, N_NORMAL_MEMORY))
3788            tmp = -1;
3789        rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
3790        if (!rtpn)
3791            return 1;
3792
3793        soft_limit_tree.rb_tree_per_node[node] = rtpn;
3794
3795        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
3796            rtpz = &rtpn->rb_tree_per_zone[zone];
3797            rtpz->rb_root = RB_ROOT;
3798            spin_lock_init(&rtpz->lock);
3799        }
3800    }
3801    return 0;
3802}
3803
3804static struct cgroup_subsys_state * __ref
3805mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
3806{
3807    struct mem_cgroup *mem, *parent;
3808    long error = -ENOMEM;
3809    int node;
3810
3811    mem = mem_cgroup_alloc();
3812    if (!mem)
3813        return ERR_PTR(error);
3814
3815    for_each_node_state(node, N_POSSIBLE)
3816        if (alloc_mem_cgroup_per_zone_info(mem, node))
3817            goto free_out;
3818
3819    /* root ? */
3820    if (cont->parent == NULL) {
3821        int cpu;
3822        enable_swap_cgroup();
3823        parent = NULL;
3824        root_mem_cgroup = mem;
3825        if (mem_cgroup_soft_limit_tree_init())
3826            goto free_out;
3827        for_each_possible_cpu(cpu) {
3828            struct memcg_stock_pcp *stock =
3829                        &per_cpu(memcg_stock, cpu);
3830            INIT_WORK(&stock->work, drain_local_stock);
3831        }
3832        hotcpu_notifier(memcg_stock_cpu_callback, 0);
3833    } else {
3834        parent = mem_cgroup_from_cont(cont->parent);
3835        mem->use_hierarchy = parent->use_hierarchy;
3836    }
3837
3838    if (parent && parent->use_hierarchy) {
3839        res_counter_init(&mem->res, &parent->res);
3840        res_counter_init(&mem->memsw, &parent->memsw);
3841        /*
3842         * We increment refcnt of the parent to ensure that we can
3843         * safely access it on res_counter_charge/uncharge.
3844         * This refcnt will be decremented when freeing this
3845         * mem_cgroup(see mem_cgroup_put).
3846         */
3847        mem_cgroup_get(parent);
3848    } else {
3849        res_counter_init(&mem->res, NULL);
3850        res_counter_init(&mem->memsw, NULL);
3851    }
3852    mem->last_scanned_child = 0;
3853    spin_lock_init(&mem->reclaim_param_lock);
3854
3855    if (parent)
3856        mem->swappiness = get_swappiness(parent);
3857    atomic_set(&mem->refcnt, 1);
3858    mem->move_charge_at_immigrate = 0;
3859    mutex_init(&mem->thresholds_lock);
3860    return &mem->css;
3861free_out:
3862    __mem_cgroup_free(mem);
3863    root_mem_cgroup = NULL;
3864    return ERR_PTR(error);
3865}
3866
3867static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
3868                    struct cgroup *cont)
3869{
3870    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3871
3872    return mem_cgroup_force_empty(mem, false);
3873}
3874
3875static void mem_cgroup_destroy(struct cgroup_subsys *ss,
3876                struct cgroup *cont)
3877{
3878    struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3879
3880    mem_cgroup_put(mem);
3881}
3882
3883static int mem_cgroup_populate(struct cgroup_subsys *ss,
3884                struct cgroup *cont)
3885{
3886    int ret;
3887
3888    ret = cgroup_add_files(cont, ss, mem_cgroup_files,
3889                ARRAY_SIZE(mem_cgroup_files));
3890
3891    if (!ret)
3892        ret = register_memsw_files(cont, ss);
3893    return ret;
3894}
3895
3896#ifdef CONFIG_MMU
3897/* Handlers for move charge at task migration. */
3898#define PRECHARGE_COUNT_AT_ONCE 256
3899static int mem_cgroup_do_precharge(unsigned long count)
3900{
3901    int ret = 0;
3902    int batch_count = PRECHARGE_COUNT_AT_ONCE;
3903    struct mem_cgroup *mem = mc.to;
3904
3905    if (mem_cgroup_is_root(mem)) {
3906        mc.precharge += count;
3907        /* we don't need css_get for root */
3908        return ret;
3909    }
3910    /* try to charge at once */
3911    if (count > 1) {
3912        struct res_counter *dummy;
3913        /*
3914         * "mem" cannot be under rmdir() because we've already checked
3915         * by cgroup_lock_live_cgroup() that it is not removed and we
3916         * are still under the same cgroup_mutex. So we can postpone
3917         * css_get().
3918         */
3919        if (res_counter_charge(&mem->res, PAGE_SIZE * count, &dummy))
3920            goto one_by_one;
3921        if (do_swap_account && res_counter_charge(&mem->memsw,
3922                        PAGE_SIZE * count, &dummy)) {
3923            res_counter_uncharge(&mem->res, PAGE_SIZE * count);
3924            goto one_by_one;
3925        }
3926        mc.precharge += count;
3927        VM_BUG_ON(test_bit(CSS_ROOT, &mem->css.flags));
3928        WARN_ON_ONCE(count > INT_MAX);
3929        __css_get(&mem->css, (int)count);
3930        return ret;
3931    }
3932one_by_one:
3933    /* fall back to one by one charge */
3934    while (count--) {
3935        if (signal_pending(current)) {
3936            ret = -EINTR;
3937            break;
3938        }
3939        if (!batch_count--) {
3940            batch_count = PRECHARGE_COUNT_AT_ONCE;
3941            cond_resched();
3942        }
3943        ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
3944        if (ret || !mem)
3945            /* mem_cgroup_clear_mc() will do uncharge later */
3946            return -ENOMEM;
3947        mc.precharge++;
3948    }
3949    return ret;
3950}
3951
3952/**
3953 * is_target_pte_for_mc - check a pte whether it is valid for move charge
3954 * @vma: the vma the pte to be checked belongs
3955 * @addr: the address corresponding to the pte to be checked
3956 * @ptent: the pte to be checked
3957 * @target: the pointer the target page or swap ent will be stored(can be NULL)
3958 *
3959 * Returns
3960 * 0(MC_TARGET_NONE): if the pte is not a target for move charge.
3961 * 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
3962 * move charge. if @target is not NULL, the page is stored in target->page
3963 * with extra refcnt got(Callers should handle it).
3964 * 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
3965 * target for charge migration. if @target is not NULL, the entry is stored
3966 * in target->ent.
3967 *
3968 * Called with pte lock held.
3969 */
3970union mc_target {
3971    struct page *page;
3972    swp_entry_t ent;
3973};
3974
3975enum mc_target_type {
3976    MC_TARGET_NONE, /* not used */
3977    MC_TARGET_PAGE,
3978    MC_TARGET_SWAP,
3979};
3980
3981static int is_target_pte_for_mc(struct vm_area_struct *vma,
3982        unsigned long addr, pte_t ptent, union mc_target *target)
3983{
3984    struct page *page = NULL;
3985    struct page_cgroup *pc;
3986    int ret = 0;
3987    swp_entry_t ent = { .val = 0 };
3988    int usage_count = 0;
3989    bool move_anon = test_bit(MOVE_CHARGE_TYPE_ANON,
3990                    &mc.to->move_charge_at_immigrate);
3991
3992    if (!pte_present(ptent)) {
3993        /* TODO: handle swap of shmes/tmpfs */
3994        if (pte_none(ptent) || pte_file(ptent))
3995            return 0;
3996        else if (is_swap_pte(ptent)) {
3997            ent = pte_to_swp_entry(ptent);
3998            if (!move_anon || non_swap_entry(ent))
3999                return 0;
4000            usage_count = mem_cgroup_count_swap_user(ent, &page);
4001        }
4002    } else {
4003        page = vm_normal_page(vma, addr, ptent);
4004        if (!page || !page_mapped(page))
4005            return 0;
4006        /*
4007         * TODO: We don't move charges of file(including shmem/tmpfs)
4008         * pages for now.
4009         */
4010        if (!move_anon || !PageAnon(page))
4011            return 0;
4012        if (!get_page_unless_zero(page))
4013            return 0;
4014        usage_count = page_mapcount(page);
4015    }
4016    if (usage_count > 1) {
4017        /*
4018         * TODO: We don't move charges of shared(used by multiple
4019         * processes) pages for now.
4020         */
4021        if (page)
4022            put_page(page);
4023        return 0;
4024    }
4025    if (page) {
4026        pc = lookup_page_cgroup(page);
4027        /*
4028         * Do only loose check w/o page_cgroup lock.
4029         * mem_cgroup_move_account() checks the pc is valid or not under
4030         * the lock.
4031         */
4032        if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
4033            ret = MC_TARGET_PAGE;
4034            if (target)
4035                target->page = page;
4036        }
4037        if (!ret || !target)
4038            put_page(page);
4039    }
4040    /* throught */
4041    if (ent.val && do_swap_account && !ret &&
4042            css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
4043        ret = MC_TARGET_SWAP;
4044        if (target)
4045            target->ent = ent;
4046    }
4047    return ret;
4048}
4049
4050static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
4051                    unsigned long addr, unsigned long end,
4052                    struct mm_walk *walk)
4053{
4054    struct vm_area_struct *vma = walk->private;
4055    pte_t *pte;
4056    spinlock_t *ptl;
4057
4058    pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4059    for (; addr != end; pte++, addr += PAGE_SIZE)
4060        if (is_target_pte_for_mc(vma, addr, *pte, NULL))
4061            mc.precharge++; /* increment precharge temporarily */
4062    pte_unmap_unlock(pte - 1, ptl);
4063    cond_resched();
4064
4065    return 0;
4066}
4067
4068static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
4069{
4070    unsigned long precharge;
4071    struct vm_area_struct *vma;
4072
4073    down_read(&mm->mmap_sem);
4074    for (vma = mm->mmap; vma; vma = vma->vm_next) {
4075        struct mm_walk mem_cgroup_count_precharge_walk = {
4076            .pmd_entry = mem_cgroup_count_precharge_pte_range,
4077            .mm = mm,
4078            .private = vma,
4079        };
4080        if (is_vm_hugetlb_page(vma))
4081            continue;
4082        /* TODO: We don't move charges of shmem/tmpfs pages for now. */
4083        if (vma->vm_flags & VM_SHARED)
4084            continue;
4085        walk_page_range(vma->vm_start, vma->vm_end,
4086                    &mem_cgroup_count_precharge_walk);
4087    }
4088    up_read(&mm->mmap_sem);
4089
4090    precharge = mc.precharge;
4091    mc.precharge = 0;
4092
4093    return precharge;
4094}
4095
4096static int mem_cgroup_precharge_mc(struct mm_struct *mm)
4097{
4098    return mem_cgroup_do_precharge(mem_cgroup_count_precharge(mm));
4099}
4100
4101static void mem_cgroup_clear_mc(void)
4102{
4103    /* we must uncharge all the leftover precharges from mc.to */
4104    if (mc.precharge) {
4105        __mem_cgroup_cancel_charge(mc.to, mc.precharge);
4106        mc.precharge = 0;
4107    }
4108    /*
4109     * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
4110     * we must uncharge here.
4111     */
4112    if (mc.moved_charge) {
4113        __mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
4114        mc.moved_charge = 0;
4115    }
4116    /* we must fixup refcnts and charges */
4117    if (mc.moved_swap) {
4118        WARN_ON_ONCE(mc.moved_swap > INT_MAX);
4119        /* uncharge swap account from the old cgroup */
4120        if (!mem_cgroup_is_root(mc.from))
4121            res_counter_uncharge(&mc.from->memsw,
4122                        PAGE_SIZE * mc.moved_swap);
4123        __mem_cgroup_put(mc.from, mc.moved_swap);
4124
4125        if (!mem_cgroup_is_root(mc.to)) {
4126            /*
4127             * we charged both to->res and to->memsw, so we should
4128             * uncharge to->res.
4129             */
4130            res_counter_uncharge(&mc.to->res,
4131                        PAGE_SIZE * mc.moved_swap);
4132            VM_BUG_ON(test_bit(CSS_ROOT, &mc.to->css.flags));
4133            __css_put(&mc.to->css, mc.moved_swap);
4134        }
4135        /* we've already done mem_cgroup_get(mc.to) */
4136
4137        mc.moved_swap = 0;
4138    }
4139    mc.from = NULL;
4140    mc.to = NULL;
4141    mc.moving_task = NULL;
4142    wake_up_all(&mc.waitq);
4143}
4144
4145static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4146                struct cgroup *cgroup,
4147                struct task_struct *p,
4148                bool threadgroup)
4149{
4150    int ret = 0;
4151    struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup);
4152
4153    if (mem->move_charge_at_immigrate) {
4154        struct mm_struct *mm;
4155        struct mem_cgroup *from = mem_cgroup_from_task(p);
4156
4157        VM_BUG_ON(from == mem);
4158
4159        mm = get_task_mm(p);
4160        if (!mm)
4161            return 0;
4162        /* We move charges only when we move a owner of the mm */
4163        if (mm->owner == p) {
4164            VM_BUG_ON(mc.from);
4165            VM_BUG_ON(mc.to);
4166            VM_BUG_ON(mc.precharge);
4167            VM_BUG_ON(mc.moved_charge);
4168            VM_BUG_ON(mc.moved_swap);
4169            VM_BUG_ON(mc.moving_task);
4170            mc.from = from;
4171            mc.to = mem;
4172            mc.precharge = 0;
4173            mc.moved_charge = 0;
4174            mc.moved_swap = 0;
4175            mc.moving_task = current;
4176
4177            ret = mem_cgroup_precharge_mc(mm);
4178            if (ret)
4179                mem_cgroup_clear_mc();
4180        }
4181        mmput(mm);
4182    }
4183    return ret;
4184}
4185
4186static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4187                struct cgroup *cgroup,
4188                struct task_struct *p,
4189                bool threadgroup)
4190{
4191    mem_cgroup_clear_mc();
4192}
4193
4194static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
4195                unsigned long addr, unsigned long end,
4196                struct mm_walk *walk)
4197{
4198    int ret = 0;
4199    struct vm_area_struct *vma = walk->private;
4200    pte_t *pte;
4201    spinlock_t *ptl;
4202
4203retry:
4204    pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4205    for (; addr != end; addr += PAGE_SIZE) {
4206        pte_t ptent = *(pte++);
4207        union mc_target target;
4208        int type;
4209        struct page *page;
4210        struct page_cgroup *pc;
4211        swp_entry_t ent;
4212
4213        if (!mc.precharge)
4214            break;
4215
4216        type = is_target_pte_for_mc(vma, addr, ptent, &target);
4217        switch (type) {
4218        case MC_TARGET_PAGE:
4219            page = target.page;
4220            if (isolate_lru_page(page))
4221                goto put;
4222            pc = lookup_page_cgroup(page);
4223            if (!mem_cgroup_move_account(pc,
4224                        mc.from, mc.to, false)) {
4225                mc.precharge--;
4226                /* we uncharge from mc.from later. */
4227                mc.moved_charge++;
4228            }
4229            putback_lru_page(page);
4230put: /* is_target_pte_for_mc() gets the page */
4231            put_page(page);
4232            break;
4233        case MC_TARGET_SWAP:
4234            ent = target.ent;
4235            if (!mem_cgroup_move_swap_account(ent,
4236                        mc.from, mc.to, false)) {
4237                mc.precharge--;
4238                /* we fixup refcnts and charges later. */
4239                mc.moved_swap++;
4240            }
4241            break;
4242        default:
4243            break;
4244        }
4245    }
4246    pte_unmap_unlock(pte - 1, ptl);
4247    cond_resched();
4248
4249    if (addr != end) {
4250        /*
4251         * We have consumed all precharges we got in can_attach().
4252         * We try charge one by one, but don't do any additional
4253         * charges to mc.to if we have failed in charge once in attach()
4254         * phase.
4255         */
4256        ret = mem_cgroup_do_precharge(1);
4257        if (!ret)
4258            goto retry;
4259    }
4260
4261    return ret;
4262}
4263
4264static void mem_cgroup_move_charge(struct mm_struct *mm)
4265{
4266    struct vm_area_struct *vma;
4267
4268    lru_add_drain_all();
4269    down_read(&mm->mmap_sem);
4270    for (vma = mm->mmap; vma; vma = vma->vm_next) {
4271        int ret;
4272        struct mm_walk mem_cgroup_move_charge_walk = {
4273            .pmd_entry = mem_cgroup_move_charge_pte_range,
4274            .mm = mm,
4275            .private = vma,
4276        };
4277        if (is_vm_hugetlb_page(vma))
4278            continue;
4279        /* TODO: We don't move charges of shmem/tmpfs pages for now. */
4280        if (vma->vm_flags & VM_SHARED)
4281            continue;
4282        ret = walk_page_range(vma->vm_start, vma->vm_end,
4283                        &mem_cgroup_move_charge_walk);
4284        if (ret)
4285            /*
4286             * means we have consumed all precharges and failed in
4287             * doing additional charge. Just abandon here.
4288             */
4289            break;
4290    }
4291    up_read(&mm->mmap_sem);
4292}
4293
4294static void mem_cgroup_move_task(struct cgroup_subsys *ss,
4295                struct cgroup *cont,
4296                struct cgroup *old_cont,
4297                struct task_struct *p,
4298                bool threadgroup)
4299{
4300    struct mm_struct *mm;
4301
4302    if (!mc.to)
4303        /* no need to move charge */
4304        return;
4305
4306    mm = get_task_mm(p);
4307    if (mm) {
4308        mem_cgroup_move_charge(mm);
4309        mmput(mm);
4310    }
4311    mem_cgroup_clear_mc();
4312}
4313#else /* !CONFIG_MMU */
4314static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4315                struct cgroup *cgroup,
4316                struct task_struct *p,
4317                bool threadgroup)
4318{
4319    return 0;
4320}
4321static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4322                struct cgroup *cgroup,
4323                struct task_struct *p,
4324                bool threadgroup)
4325{
4326}
4327static void mem_cgroup_move_task(struct cgroup_subsys *ss,
4328                struct cgroup *cont,
4329                struct cgroup *old_cont,
4330                struct task_struct *p,
4331                bool threadgroup)
4332{
4333}
4334#endif
4335
4336struct cgroup_subsys mem_cgroup_subsys = {
4337    .name = "memory",
4338    .subsys_id = mem_cgroup_subsys_id,
4339    .create = mem_cgroup_create,
4340    .pre_destroy = mem_cgroup_pre_destroy,
4341    .destroy = mem_cgroup_destroy,
4342    .populate = mem_cgroup_populate,
4343    .can_attach = mem_cgroup_can_attach,
4344    .cancel_attach = mem_cgroup_cancel_attach,
4345    .attach = mem_cgroup_move_task,
4346    .early_init = 0,
4347    .use_id = 1,
4348};
4349
4350#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4351
4352static int __init disable_swap_account(char *s)
4353{
4354    really_do_swap_account = 0;
4355    return 1;
4356}
4357__setup("noswapaccount", disable_swap_account);
4358#endif
4359

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