memcg: fix race in file_mapped accouting flag management
[linux-2.6.git] / mm / memcontrol.c
1 /* memcontrol.c - Memory Controller
2  *
3  * Copyright IBM Corporation, 2007
4  * Author Balbir Singh <balbir@linux.vnet.ibm.com>
5  *
6  * Copyright 2007 OpenVZ SWsoft Inc
7  * Author: Pavel Emelianov <xemul@openvz.org>
8  *
9  * Memory thresholds
10  * Copyright (C) 2009 Nokia Corporation
11  * Author: Kirill A. Shutemov
12  *
13  * This program is free software; you can redistribute it and/or modify
14  * it under the terms of the GNU General Public License as published by
15  * the Free Software Foundation; either version 2 of the License, or
16  * (at your option) any later version.
17  *
18  * This program is distributed in the hope that it will be useful,
19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
21  * GNU General Public License for more details.
22  */
23
24 #include <linux/res_counter.h>
25 #include <linux/memcontrol.h>
26 #include <linux/cgroup.h>
27 #include <linux/mm.h>
28 #include <linux/hugetlb.h>
29 #include <linux/pagemap.h>
30 #include <linux/smp.h>
31 #include <linux/page-flags.h>
32 #include <linux/backing-dev.h>
33 #include <linux/bit_spinlock.h>
34 #include <linux/rcupdate.h>
35 #include <linux/limits.h>
36 #include <linux/mutex.h>
37 #include <linux/rbtree.h>
38 #include <linux/slab.h>
39 #include <linux/swap.h>
40 #include <linux/swapops.h>
41 #include <linux/spinlock.h>
42 #include <linux/eventfd.h>
43 #include <linux/sort.h>
44 #include <linux/fs.h>
45 #include <linux/seq_file.h>
46 #include <linux/vmalloc.h>
47 #include <linux/mm_inline.h>
48 #include <linux/page_cgroup.h>
49 #include <linux/cpu.h>
50 #include <linux/oom.h>
51 #include "internal.h"
52
53 #include <asm/uaccess.h>
54
55 #include <trace/events/vmscan.h>
56
57 struct cgroup_subsys mem_cgroup_subsys __read_mostly;
58 #define MEM_CGROUP_RECLAIM_RETRIES      5
59 struct mem_cgroup *root_mem_cgroup __read_mostly;
60
61 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
62 /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
63 int do_swap_account __read_mostly;
64 static int really_do_swap_account __initdata = 1; /* for remember boot option*/
65 #else
66 #define do_swap_account         (0)
67 #endif
68
69 /*
70  * Per memcg event counter is incremented at every pagein/pageout. This counter
71  * is used for trigger some periodic events. This is straightforward and better
72  * than using jiffies etc. to handle periodic memcg event.
73  *
74  * These values will be used as !((event) & ((1 <<(thresh)) - 1))
75  */
76 #define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
77 #define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
78
79 /*
80  * Statistics for memory cgroup.
81  */
82 enum mem_cgroup_stat_index {
83         /*
84          * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
85          */
86         MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
87         MEM_CGROUP_STAT_RSS,       /* # of pages charged as anon rss */
88         MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
89         MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
90         MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
91         MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
92         MEM_CGROUP_EVENTS,      /* incremented at every  pagein/pageout */
93
94         MEM_CGROUP_STAT_NSTATS,
95 };
96
97 struct mem_cgroup_stat_cpu {
98         s64 count[MEM_CGROUP_STAT_NSTATS];
99 };
100
101 /*
102  * per-zone information in memory controller.
103  */
104 struct mem_cgroup_per_zone {
105         /*
106          * spin_lock to protect the per cgroup LRU
107          */
108         struct list_head        lists[NR_LRU_LISTS];
109         unsigned long           count[NR_LRU_LISTS];
110
111         struct zone_reclaim_stat reclaim_stat;
112         struct rb_node          tree_node;      /* RB tree node */
113         unsigned long long      usage_in_excess;/* Set to the value by which */
114                                                 /* the soft limit is exceeded*/
115         bool                    on_tree;
116         struct mem_cgroup       *mem;           /* Back pointer, we cannot */
117                                                 /* use container_of        */
118 };
119 /* Macro for accessing counter */
120 #define MEM_CGROUP_ZSTAT(mz, idx)       ((mz)->count[(idx)])
121
122 struct mem_cgroup_per_node {
123         struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
124 };
125
126 struct mem_cgroup_lru_info {
127         struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
128 };
129
130 /*
131  * Cgroups above their limits are maintained in a RB-Tree, independent of
132  * their hierarchy representation
133  */
134
135 struct mem_cgroup_tree_per_zone {
136         struct rb_root rb_root;
137         spinlock_t lock;
138 };
139
140 struct mem_cgroup_tree_per_node {
141         struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
142 };
143
144 struct mem_cgroup_tree {
145         struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
146 };
147
148 static struct mem_cgroup_tree soft_limit_tree __read_mostly;
149
150 struct mem_cgroup_threshold {
151         struct eventfd_ctx *eventfd;
152         u64 threshold;
153 };
154
155 /* For threshold */
156 struct mem_cgroup_threshold_ary {
157         /* An array index points to threshold just below usage. */
158         int current_threshold;
159         /* Size of entries[] */
160         unsigned int size;
161         /* Array of thresholds */
162         struct mem_cgroup_threshold entries[0];
163 };
164
165 struct mem_cgroup_thresholds {
166         /* Primary thresholds array */
167         struct mem_cgroup_threshold_ary *primary;
168         /*
169          * Spare threshold array.
170          * This is needed to make mem_cgroup_unregister_event() "never fail".
171          * It must be able to store at least primary->size - 1 entries.
172          */
173         struct mem_cgroup_threshold_ary *spare;
174 };
175
176 /* for OOM */
177 struct mem_cgroup_eventfd_list {
178         struct list_head list;
179         struct eventfd_ctx *eventfd;
180 };
181
182 static void mem_cgroup_threshold(struct mem_cgroup *mem);
183 static void mem_cgroup_oom_notify(struct mem_cgroup *mem);
184
185 /*
186  * The memory controller data structure. The memory controller controls both
187  * page cache and RSS per cgroup. We would eventually like to provide
188  * statistics based on the statistics developed by Rik Van Riel for clock-pro,
189  * to help the administrator determine what knobs to tune.
190  *
191  * TODO: Add a water mark for the memory controller. Reclaim will begin when
192  * we hit the water mark. May be even add a low water mark, such that
193  * no reclaim occurs from a cgroup at it's low water mark, this is
194  * a feature that will be implemented much later in the future.
195  */
196 struct mem_cgroup {
197         struct cgroup_subsys_state css;
198         /*
199          * the counter to account for memory usage
200          */
201         struct res_counter res;
202         /*
203          * the counter to account for mem+swap usage.
204          */
205         struct res_counter memsw;
206         /*
207          * Per cgroup active and inactive list, similar to the
208          * per zone LRU lists.
209          */
210         struct mem_cgroup_lru_info info;
211
212         /*
213           protect against reclaim related member.
214         */
215         spinlock_t reclaim_param_lock;
216
217         /*
218          * While reclaiming in a hierarchy, we cache the last child we
219          * reclaimed from.
220          */
221         int last_scanned_child;
222         /*
223          * Should the accounting and control be hierarchical, per subtree?
224          */
225         bool use_hierarchy;
226         atomic_t        oom_lock;
227         atomic_t        refcnt;
228
229         unsigned int    swappiness;
230         /* OOM-Killer disable */
231         int             oom_kill_disable;
232
233         /* set when res.limit == memsw.limit */
234         bool            memsw_is_minimum;
235
236         /* protect arrays of thresholds */
237         struct mutex thresholds_lock;
238
239         /* thresholds for memory usage. RCU-protected */
240         struct mem_cgroup_thresholds thresholds;
241
242         /* thresholds for mem+swap usage. RCU-protected */
243         struct mem_cgroup_thresholds memsw_thresholds;
244
245         /* For oom notifier event fd */
246         struct list_head oom_notify;
247
248         /*
249          * Should we move charges of a task when a task is moved into this
250          * mem_cgroup ? And what type of charges should we move ?
251          */
252         unsigned long   move_charge_at_immigrate;
253         /*
254          * percpu counter.
255          */
256         struct mem_cgroup_stat_cpu *stat;
257 };
258
259 /* Stuffs for move charges at task migration. */
260 /*
261  * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
262  * left-shifted bitmap of these types.
263  */
264 enum move_type {
265         MOVE_CHARGE_TYPE_ANON,  /* private anonymous page and swap of it */
266         MOVE_CHARGE_TYPE_FILE,  /* file page(including tmpfs) and swap of it */
267         NR_MOVE_TYPE,
268 };
269
270 /* "mc" and its members are protected by cgroup_mutex */
271 static struct move_charge_struct {
272         spinlock_t        lock; /* for from, to, moving_task */
273         struct mem_cgroup *from;
274         struct mem_cgroup *to;
275         unsigned long precharge;
276         unsigned long moved_charge;
277         unsigned long moved_swap;
278         struct task_struct *moving_task;        /* a task moving charges */
279         wait_queue_head_t waitq;                /* a waitq for other context */
280 } mc = {
281         .lock = __SPIN_LOCK_UNLOCKED(mc.lock),
282         .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
283 };
284
285 static bool move_anon(void)
286 {
287         return test_bit(MOVE_CHARGE_TYPE_ANON,
288                                         &mc.to->move_charge_at_immigrate);
289 }
290
291 static bool move_file(void)
292 {
293         return test_bit(MOVE_CHARGE_TYPE_FILE,
294                                         &mc.to->move_charge_at_immigrate);
295 }
296
297 /*
298  * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
299  * limit reclaim to prevent infinite loops, if they ever occur.
300  */
301 #define MEM_CGROUP_MAX_RECLAIM_LOOPS            (100)
302 #define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2)
303
304 enum charge_type {
305         MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
306         MEM_CGROUP_CHARGE_TYPE_MAPPED,
307         MEM_CGROUP_CHARGE_TYPE_SHMEM,   /* used by page migration of shmem */
308         MEM_CGROUP_CHARGE_TYPE_FORCE,   /* used by force_empty */
309         MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
310         MEM_CGROUP_CHARGE_TYPE_DROP,    /* a page was unused swap cache */
311         NR_CHARGE_TYPE,
312 };
313
314 /* only for here (for easy reading.) */
315 #define PCGF_CACHE      (1UL << PCG_CACHE)
316 #define PCGF_USED       (1UL << PCG_USED)
317 #define PCGF_LOCK       (1UL << PCG_LOCK)
318 /* Not used, but added here for completeness */
319 #define PCGF_ACCT       (1UL << PCG_ACCT)
320
321 /* for encoding cft->private value on file */
322 #define _MEM                    (0)
323 #define _MEMSWAP                (1)
324 #define _OOM_TYPE               (2)
325 #define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
326 #define MEMFILE_TYPE(val)       (((val) >> 16) & 0xffff)
327 #define MEMFILE_ATTR(val)       ((val) & 0xffff)
328 /* Used for OOM nofiier */
329 #define OOM_CONTROL             (0)
330
331 /*
332  * Reclaim flags for mem_cgroup_hierarchical_reclaim
333  */
334 #define MEM_CGROUP_RECLAIM_NOSWAP_BIT   0x0
335 #define MEM_CGROUP_RECLAIM_NOSWAP       (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
336 #define MEM_CGROUP_RECLAIM_SHRINK_BIT   0x1
337 #define MEM_CGROUP_RECLAIM_SHRINK       (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
338 #define MEM_CGROUP_RECLAIM_SOFT_BIT     0x2
339 #define MEM_CGROUP_RECLAIM_SOFT         (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
340
341 static void mem_cgroup_get(struct mem_cgroup *mem);
342 static void mem_cgroup_put(struct mem_cgroup *mem);
343 static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
344 static void drain_all_stock_async(void);
345
346 static struct mem_cgroup_per_zone *
347 mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
348 {
349         return &mem->info.nodeinfo[nid]->zoneinfo[zid];
350 }
351
352 struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
353 {
354         return &mem->css;
355 }
356
357 static struct mem_cgroup_per_zone *
358 page_cgroup_zoneinfo(struct page_cgroup *pc)
359 {
360         struct mem_cgroup *mem = pc->mem_cgroup;
361         int nid = page_cgroup_nid(pc);
362         int zid = page_cgroup_zid(pc);
363
364         if (!mem)
365                 return NULL;
366
367         return mem_cgroup_zoneinfo(mem, nid, zid);
368 }
369
370 static struct mem_cgroup_tree_per_zone *
371 soft_limit_tree_node_zone(int nid, int zid)
372 {
373         return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
374 }
375
376 static struct mem_cgroup_tree_per_zone *
377 soft_limit_tree_from_page(struct page *page)
378 {
379         int nid = page_to_nid(page);
380         int zid = page_zonenum(page);
381
382         return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
383 }
384
385 static void
386 __mem_cgroup_insert_exceeded(struct mem_cgroup *mem,
387                                 struct mem_cgroup_per_zone *mz,
388                                 struct mem_cgroup_tree_per_zone *mctz,
389                                 unsigned long long new_usage_in_excess)
390 {
391         struct rb_node **p = &mctz->rb_root.rb_node;
392         struct rb_node *parent = NULL;
393         struct mem_cgroup_per_zone *mz_node;
394
395         if (mz->on_tree)
396                 return;
397
398         mz->usage_in_excess = new_usage_in_excess;
399         if (!mz->usage_in_excess)
400                 return;
401         while (*p) {
402                 parent = *p;
403                 mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
404                                         tree_node);
405                 if (mz->usage_in_excess < mz_node->usage_in_excess)
406                         p = &(*p)->rb_left;
407                 /*
408                  * We can't avoid mem cgroups that are over their soft
409                  * limit by the same amount
410                  */
411                 else if (mz->usage_in_excess >= mz_node->usage_in_excess)
412                         p = &(*p)->rb_right;
413         }
414         rb_link_node(&mz->tree_node, parent, p);
415         rb_insert_color(&mz->tree_node, &mctz->rb_root);
416         mz->on_tree = true;
417 }
418
419 static void
420 __mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
421                                 struct mem_cgroup_per_zone *mz,
422                                 struct mem_cgroup_tree_per_zone *mctz)
423 {
424         if (!mz->on_tree)
425                 return;
426         rb_erase(&mz->tree_node, &mctz->rb_root);
427         mz->on_tree = false;
428 }
429
430 static void
431 mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
432                                 struct mem_cgroup_per_zone *mz,
433                                 struct mem_cgroup_tree_per_zone *mctz)
434 {
435         spin_lock(&mctz->lock);
436         __mem_cgroup_remove_exceeded(mem, mz, mctz);
437         spin_unlock(&mctz->lock);
438 }
439
440
441 static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
442 {
443         unsigned long long excess;
444         struct mem_cgroup_per_zone *mz;
445         struct mem_cgroup_tree_per_zone *mctz;
446         int nid = page_to_nid(page);
447         int zid = page_zonenum(page);
448         mctz = soft_limit_tree_from_page(page);
449
450         /*
451          * Necessary to update all ancestors when hierarchy is used.
452          * because their event counter is not touched.
453          */
454         for (; mem; mem = parent_mem_cgroup(mem)) {
455                 mz = mem_cgroup_zoneinfo(mem, nid, zid);
456                 excess = res_counter_soft_limit_excess(&mem->res);
457                 /*
458                  * We have to update the tree if mz is on RB-tree or
459                  * mem is over its softlimit.
460                  */
461                 if (excess || mz->on_tree) {
462                         spin_lock(&mctz->lock);
463                         /* if on-tree, remove it */
464                         if (mz->on_tree)
465                                 __mem_cgroup_remove_exceeded(mem, mz, mctz);
466                         /*
467                          * Insert again. mz->usage_in_excess will be updated.
468                          * If excess is 0, no tree ops.
469                          */
470                         __mem_cgroup_insert_exceeded(mem, mz, mctz, excess);
471                         spin_unlock(&mctz->lock);
472                 }
473         }
474 }
475
476 static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
477 {
478         int node, zone;
479         struct mem_cgroup_per_zone *mz;
480         struct mem_cgroup_tree_per_zone *mctz;
481
482         for_each_node_state(node, N_POSSIBLE) {
483                 for (zone = 0; zone < MAX_NR_ZONES; zone++) {
484                         mz = mem_cgroup_zoneinfo(mem, node, zone);
485                         mctz = soft_limit_tree_node_zone(node, zone);
486                         mem_cgroup_remove_exceeded(mem, mz, mctz);
487                 }
488         }
489 }
490
491 static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
492 {
493         return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
494 }
495
496 static struct mem_cgroup_per_zone *
497 __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
498 {
499         struct rb_node *rightmost = NULL;
500         struct mem_cgroup_per_zone *mz;
501
502 retry:
503         mz = NULL;
504         rightmost = rb_last(&mctz->rb_root);
505         if (!rightmost)
506                 goto done;              /* Nothing to reclaim from */
507
508         mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
509         /*
510          * Remove the node now but someone else can add it back,
511          * we will to add it back at the end of reclaim to its correct
512          * position in the tree.
513          */
514         __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
515         if (!res_counter_soft_limit_excess(&mz->mem->res) ||
516                 !css_tryget(&mz->mem->css))
517                 goto retry;
518 done:
519         return mz;
520 }
521
522 static struct mem_cgroup_per_zone *
523 mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
524 {
525         struct mem_cgroup_per_zone *mz;
526
527         spin_lock(&mctz->lock);
528         mz = __mem_cgroup_largest_soft_limit_node(mctz);
529         spin_unlock(&mctz->lock);
530         return mz;
531 }
532
533 static s64 mem_cgroup_read_stat(struct mem_cgroup *mem,
534                 enum mem_cgroup_stat_index idx)
535 {
536         int cpu;
537         s64 val = 0;
538
539         for_each_possible_cpu(cpu)
540                 val += per_cpu(mem->stat->count[idx], cpu);
541         return val;
542 }
543
544 static s64 mem_cgroup_local_usage(struct mem_cgroup *mem)
545 {
546         s64 ret;
547
548         ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
549         ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
550         return ret;
551 }
552
553 static void mem_cgroup_swap_statistics(struct mem_cgroup *mem,
554                                          bool charge)
555 {
556         int val = (charge) ? 1 : -1;
557         this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
558 }
559
560 static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
561                                          struct page_cgroup *pc,
562                                          bool charge)
563 {
564         int val = (charge) ? 1 : -1;
565
566         preempt_disable();
567
568         if (PageCgroupCache(pc))
569                 __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_CACHE], val);
570         else
571                 __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_RSS], val);
572
573         if (charge)
574                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
575         else
576                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
577         __this_cpu_inc(mem->stat->count[MEM_CGROUP_EVENTS]);
578
579         preempt_enable();
580 }
581
582 static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
583                                         enum lru_list idx)
584 {
585         int nid, zid;
586         struct mem_cgroup_per_zone *mz;
587         u64 total = 0;
588
589         for_each_online_node(nid)
590                 for (zid = 0; zid < MAX_NR_ZONES; zid++) {
591                         mz = mem_cgroup_zoneinfo(mem, nid, zid);
592                         total += MEM_CGROUP_ZSTAT(mz, idx);
593                 }
594         return total;
595 }
596
597 static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
598 {
599         s64 val;
600
601         val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
602
603         return !(val & ((1 << event_mask_shift) - 1));
604 }
605
606 /*
607  * Check events in order.
608  *
609  */
610 static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
611 {
612         /* threshold event is triggered in finer grain than soft limit */
613         if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
614                 mem_cgroup_threshold(mem);
615                 if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
616                         mem_cgroup_update_tree(mem, page);
617         }
618 }
619
620 static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
621 {
622         return container_of(cgroup_subsys_state(cont,
623                                 mem_cgroup_subsys_id), struct mem_cgroup,
624                                 css);
625 }
626
627 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
628 {
629         /*
630          * mm_update_next_owner() may clear mm->owner to NULL
631          * if it races with swapoff, page migration, etc.
632          * So this can be called with p == NULL.
633          */
634         if (unlikely(!p))
635                 return NULL;
636
637         return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
638                                 struct mem_cgroup, css);
639 }
640
641 static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
642 {
643         struct mem_cgroup *mem = NULL;
644
645         if (!mm)
646                 return NULL;
647         /*
648          * Because we have no locks, mm->owner's may be being moved to other
649          * cgroup. We use css_tryget() here even if this looks
650          * pessimistic (rather than adding locks here).
651          */
652         rcu_read_lock();
653         do {
654                 mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
655                 if (unlikely(!mem))
656                         break;
657         } while (!css_tryget(&mem->css));
658         rcu_read_unlock();
659         return mem;
660 }
661
662 /*
663  * Call callback function against all cgroup under hierarchy tree.
664  */
665 static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
666                           int (*func)(struct mem_cgroup *, void *))
667 {
668         int found, ret, nextid;
669         struct cgroup_subsys_state *css;
670         struct mem_cgroup *mem;
671
672         if (!root->use_hierarchy)
673                 return (*func)(root, data);
674
675         nextid = 1;
676         do {
677                 ret = 0;
678                 mem = NULL;
679
680                 rcu_read_lock();
681                 css = css_get_next(&mem_cgroup_subsys, nextid, &root->css,
682                                    &found);
683                 if (css && css_tryget(css))
684                         mem = container_of(css, struct mem_cgroup, css);
685                 rcu_read_unlock();
686
687                 if (mem) {
688                         ret = (*func)(mem, data);
689                         css_put(&mem->css);
690                 }
691                 nextid = found + 1;
692         } while (!ret && css);
693
694         return ret;
695 }
696
697 static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
698 {
699         return (mem == root_mem_cgroup);
700 }
701
702 /*
703  * Following LRU functions are allowed to be used without PCG_LOCK.
704  * Operations are called by routine of global LRU independently from memcg.
705  * What we have to take care of here is validness of pc->mem_cgroup.
706  *
707  * Changes to pc->mem_cgroup happens when
708  * 1. charge
709  * 2. moving account
710  * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
711  * It is added to LRU before charge.
712  * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
713  * When moving account, the page is not on LRU. It's isolated.
714  */
715
716 void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
717 {
718         struct page_cgroup *pc;
719         struct mem_cgroup_per_zone *mz;
720
721         if (mem_cgroup_disabled())
722                 return;
723         pc = lookup_page_cgroup(page);
724         /* can happen while we handle swapcache. */
725         if (!TestClearPageCgroupAcctLRU(pc))
726                 return;
727         VM_BUG_ON(!pc->mem_cgroup);
728         /*
729          * We don't check PCG_USED bit. It's cleared when the "page" is finally
730          * removed from global LRU.
731          */
732         mz = page_cgroup_zoneinfo(pc);
733         MEM_CGROUP_ZSTAT(mz, lru) -= 1;
734         if (mem_cgroup_is_root(pc->mem_cgroup))
735                 return;
736         VM_BUG_ON(list_empty(&pc->lru));
737         list_del_init(&pc->lru);
738         return;
739 }
740
741 void mem_cgroup_del_lru(struct page *page)
742 {
743         mem_cgroup_del_lru_list(page, page_lru(page));
744 }
745
746 void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
747 {
748         struct mem_cgroup_per_zone *mz;
749         struct page_cgroup *pc;
750
751         if (mem_cgroup_disabled())
752                 return;
753
754         pc = lookup_page_cgroup(page);
755         /*
756          * Used bit is set without atomic ops but after smp_wmb().
757          * For making pc->mem_cgroup visible, insert smp_rmb() here.
758          */
759         smp_rmb();
760         /* unused or root page is not rotated. */
761         if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
762                 return;
763         mz = page_cgroup_zoneinfo(pc);
764         list_move(&pc->lru, &mz->lists[lru]);
765 }
766
767 void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
768 {
769         struct page_cgroup *pc;
770         struct mem_cgroup_per_zone *mz;
771
772         if (mem_cgroup_disabled())
773                 return;
774         pc = lookup_page_cgroup(page);
775         VM_BUG_ON(PageCgroupAcctLRU(pc));
776         /*
777          * Used bit is set without atomic ops but after smp_wmb().
778          * For making pc->mem_cgroup visible, insert smp_rmb() here.
779          */
780         smp_rmb();
781         if (!PageCgroupUsed(pc))
782                 return;
783
784         mz = page_cgroup_zoneinfo(pc);
785         MEM_CGROUP_ZSTAT(mz, lru) += 1;
786         SetPageCgroupAcctLRU(pc);
787         if (mem_cgroup_is_root(pc->mem_cgroup))
788                 return;
789         list_add(&pc->lru, &mz->lists[lru]);
790 }
791
792 /*
793  * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
794  * lru because the page may.be reused after it's fully uncharged (because of
795  * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
796  * it again. This function is only used to charge SwapCache. It's done under
797  * lock_page and expected that zone->lru_lock is never held.
798  */
799 static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
800 {
801         unsigned long flags;
802         struct zone *zone = page_zone(page);
803         struct page_cgroup *pc = lookup_page_cgroup(page);
804
805         spin_lock_irqsave(&zone->lru_lock, flags);
806         /*
807          * Forget old LRU when this page_cgroup is *not* used. This Used bit
808          * is guarded by lock_page() because the page is SwapCache.
809          */
810         if (!PageCgroupUsed(pc))
811                 mem_cgroup_del_lru_list(page, page_lru(page));
812         spin_unlock_irqrestore(&zone->lru_lock, flags);
813 }
814
815 static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
816 {
817         unsigned long flags;
818         struct zone *zone = page_zone(page);
819         struct page_cgroup *pc = lookup_page_cgroup(page);
820
821         spin_lock_irqsave(&zone->lru_lock, flags);
822         /* link when the page is linked to LRU but page_cgroup isn't */
823         if (PageLRU(page) && !PageCgroupAcctLRU(pc))
824                 mem_cgroup_add_lru_list(page, page_lru(page));
825         spin_unlock_irqrestore(&zone->lru_lock, flags);
826 }
827
828
829 void mem_cgroup_move_lists(struct page *page,
830                            enum lru_list from, enum lru_list to)
831 {
832         if (mem_cgroup_disabled())
833                 return;
834         mem_cgroup_del_lru_list(page, from);
835         mem_cgroup_add_lru_list(page, to);
836 }
837
838 int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
839 {
840         int ret;
841         struct mem_cgroup *curr = NULL;
842         struct task_struct *p;
843
844         p = find_lock_task_mm(task);
845         if (!p)
846                 return 0;
847         curr = try_get_mem_cgroup_from_mm(p->mm);
848         task_unlock(p);
849         if (!curr)
850                 return 0;
851         /*
852          * We should check use_hierarchy of "mem" not "curr". Because checking
853          * use_hierarchy of "curr" here make this function true if hierarchy is
854          * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
855          * hierarchy(even if use_hierarchy is disabled in "mem").
856          */
857         if (mem->use_hierarchy)
858                 ret = css_is_ancestor(&curr->css, &mem->css);
859         else
860                 ret = (curr == mem);
861         css_put(&curr->css);
862         return ret;
863 }
864
865 static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
866 {
867         unsigned long active;
868         unsigned long inactive;
869         unsigned long gb;
870         unsigned long inactive_ratio;
871
872         inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_ANON);
873         active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_ANON);
874
875         gb = (inactive + active) >> (30 - PAGE_SHIFT);
876         if (gb)
877                 inactive_ratio = int_sqrt(10 * gb);
878         else
879                 inactive_ratio = 1;
880
881         if (present_pages) {
882                 present_pages[0] = inactive;
883                 present_pages[1] = active;
884         }
885
886         return inactive_ratio;
887 }
888
889 int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
890 {
891         unsigned long active;
892         unsigned long inactive;
893         unsigned long present_pages[2];
894         unsigned long inactive_ratio;
895
896         inactive_ratio = calc_inactive_ratio(memcg, present_pages);
897
898         inactive = present_pages[0];
899         active = present_pages[1];
900
901         if (inactive * inactive_ratio < active)
902                 return 1;
903
904         return 0;
905 }
906
907 int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
908 {
909         unsigned long active;
910         unsigned long inactive;
911
912         inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE);
913         active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE);
914
915         return (active > inactive);
916 }
917
918 unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
919                                        struct zone *zone,
920                                        enum lru_list lru)
921 {
922         int nid = zone_to_nid(zone);
923         int zid = zone_idx(zone);
924         struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
925
926         return MEM_CGROUP_ZSTAT(mz, lru);
927 }
928
929 struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
930                                                       struct zone *zone)
931 {
932         int nid = zone_to_nid(zone);
933         int zid = zone_idx(zone);
934         struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
935
936         return &mz->reclaim_stat;
937 }
938
939 struct zone_reclaim_stat *
940 mem_cgroup_get_reclaim_stat_from_page(struct page *page)
941 {
942         struct page_cgroup *pc;
943         struct mem_cgroup_per_zone *mz;
944
945         if (mem_cgroup_disabled())
946                 return NULL;
947
948         pc = lookup_page_cgroup(page);
949         /*
950          * Used bit is set without atomic ops but after smp_wmb().
951          * For making pc->mem_cgroup visible, insert smp_rmb() here.
952          */
953         smp_rmb();
954         if (!PageCgroupUsed(pc))
955                 return NULL;
956
957         mz = page_cgroup_zoneinfo(pc);
958         if (!mz)
959                 return NULL;
960
961         return &mz->reclaim_stat;
962 }
963
964 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
965                                         struct list_head *dst,
966                                         unsigned long *scanned, int order,
967                                         int mode, struct zone *z,
968                                         struct mem_cgroup *mem_cont,
969                                         int active, int file)
970 {
971         unsigned long nr_taken = 0;
972         struct page *page;
973         unsigned long scan;
974         LIST_HEAD(pc_list);
975         struct list_head *src;
976         struct page_cgroup *pc, *tmp;
977         int nid = zone_to_nid(z);
978         int zid = zone_idx(z);
979         struct mem_cgroup_per_zone *mz;
980         int lru = LRU_FILE * file + active;
981         int ret;
982
983         BUG_ON(!mem_cont);
984         mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
985         src = &mz->lists[lru];
986
987         scan = 0;
988         list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
989                 if (scan >= nr_to_scan)
990                         break;
991
992                 page = pc->page;
993                 if (unlikely(!PageCgroupUsed(pc)))
994                         continue;
995                 if (unlikely(!PageLRU(page)))
996                         continue;
997
998                 scan++;
999                 ret = __isolate_lru_page(page, mode, file);
1000                 switch (ret) {
1001                 case 0:
1002                         list_move(&page->lru, dst);
1003                         mem_cgroup_del_lru(page);
1004                         nr_taken++;
1005                         break;
1006                 case -EBUSY:
1007                         /* we don't affect global LRU but rotate in our LRU */
1008                         mem_cgroup_rotate_lru_list(page, page_lru(page));
1009                         break;
1010                 default:
1011                         break;
1012                 }
1013         }
1014
1015         *scanned = scan;
1016
1017         trace_mm_vmscan_memcg_isolate(0, nr_to_scan, scan, nr_taken,
1018                                       0, 0, 0, mode);
1019
1020         return nr_taken;
1021 }
1022
1023 #define mem_cgroup_from_res_counter(counter, member)    \
1024         container_of(counter, struct mem_cgroup, member)
1025
1026 static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
1027 {
1028         if (do_swap_account) {
1029                 if (res_counter_check_under_limit(&mem->res) &&
1030                         res_counter_check_under_limit(&mem->memsw))
1031                         return true;
1032         } else
1033                 if (res_counter_check_under_limit(&mem->res))
1034                         return true;
1035         return false;
1036 }
1037
1038 static unsigned int get_swappiness(struct mem_cgroup *memcg)
1039 {
1040         struct cgroup *cgrp = memcg->css.cgroup;
1041         unsigned int swappiness;
1042
1043         /* root ? */
1044         if (cgrp->parent == NULL)
1045                 return vm_swappiness;
1046
1047         spin_lock(&memcg->reclaim_param_lock);
1048         swappiness = memcg->swappiness;
1049         spin_unlock(&memcg->reclaim_param_lock);
1050
1051         return swappiness;
1052 }
1053
1054 /* A routine for testing mem is not under move_account */
1055
1056 static bool mem_cgroup_under_move(struct mem_cgroup *mem)
1057 {
1058         struct mem_cgroup *from;
1059         struct mem_cgroup *to;
1060         bool ret = false;
1061         /*
1062          * Unlike task_move routines, we access mc.to, mc.from not under
1063          * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
1064          */
1065         spin_lock(&mc.lock);
1066         from = mc.from;
1067         to = mc.to;
1068         if (!from)
1069                 goto unlock;
1070         if (from == mem || to == mem
1071             || (mem->use_hierarchy && css_is_ancestor(&from->css, &mem->css))
1072             || (mem->use_hierarchy && css_is_ancestor(&to->css, &mem->css)))
1073                 ret = true;
1074 unlock:
1075         spin_unlock(&mc.lock);
1076         return ret;
1077 }
1078
1079 static bool mem_cgroup_wait_acct_move(struct mem_cgroup *mem)
1080 {
1081         if (mc.moving_task && current != mc.moving_task) {
1082                 if (mem_cgroup_under_move(mem)) {
1083                         DEFINE_WAIT(wait);
1084                         prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
1085                         /* moving charge context might have finished. */
1086                         if (mc.moving_task)
1087                                 schedule();
1088                         finish_wait(&mc.waitq, &wait);
1089                         return true;
1090                 }
1091         }
1092         return false;
1093 }
1094
1095 static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
1096 {
1097         int *val = data;
1098         (*val)++;
1099         return 0;
1100 }
1101
1102 /**
1103  * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
1104  * @memcg: The memory cgroup that went over limit
1105  * @p: Task that is going to be killed
1106  *
1107  * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1108  * enabled
1109  */
1110 void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
1111 {
1112         struct cgroup *task_cgrp;
1113         struct cgroup *mem_cgrp;
1114         /*
1115          * Need a buffer in BSS, can't rely on allocations. The code relies
1116          * on the assumption that OOM is serialized for memory controller.
1117          * If this assumption is broken, revisit this code.
1118          */
1119         static char memcg_name[PATH_MAX];
1120         int ret;
1121
1122         if (!memcg || !p)
1123                 return;
1124
1125
1126         rcu_read_lock();
1127
1128         mem_cgrp = memcg->css.cgroup;
1129         task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
1130
1131         ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
1132         if (ret < 0) {
1133                 /*
1134                  * Unfortunately, we are unable to convert to a useful name
1135                  * But we'll still print out the usage information
1136                  */
1137                 rcu_read_unlock();
1138                 goto done;
1139         }
1140         rcu_read_unlock();
1141
1142         printk(KERN_INFO "Task in %s killed", memcg_name);
1143
1144         rcu_read_lock();
1145         ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
1146         if (ret < 0) {
1147                 rcu_read_unlock();
1148                 goto done;
1149         }
1150         rcu_read_unlock();
1151
1152         /*
1153          * Continues from above, so we don't need an KERN_ level
1154          */
1155         printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
1156 done:
1157
1158         printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
1159                 res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
1160                 res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
1161                 res_counter_read_u64(&memcg->res, RES_FAILCNT));
1162         printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
1163                 "failcnt %llu\n",
1164                 res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
1165                 res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
1166                 res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1167 }
1168
1169 /*
1170  * This function returns the number of memcg under hierarchy tree. Returns
1171  * 1(self count) if no children.
1172  */
1173 static int mem_cgroup_count_children(struct mem_cgroup *mem)
1174 {
1175         int num = 0;
1176         mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb);
1177         return num;
1178 }
1179
1180 /*
1181  * Return the memory (and swap, if configured) limit for a memcg.
1182  */
1183 u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
1184 {
1185         u64 limit;
1186         u64 memsw;
1187
1188         limit = res_counter_read_u64(&memcg->res, RES_LIMIT) +
1189                         total_swap_pages;
1190         memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1191         /*
1192          * If memsw is finite and limits the amount of swap space available
1193          * to this memcg, return that limit.
1194          */
1195         return min(limit, memsw);
1196 }
1197
1198 /*
1199  * Visit the first child (need not be the first child as per the ordering
1200  * of the cgroup list, since we track last_scanned_child) of @mem and use
1201  * that to reclaim free pages from.
1202  */
1203 static struct mem_cgroup *
1204 mem_cgroup_select_victim(struct mem_cgroup *root_mem)
1205 {
1206         struct mem_cgroup *ret = NULL;
1207         struct cgroup_subsys_state *css;
1208         int nextid, found;
1209
1210         if (!root_mem->use_hierarchy) {
1211                 css_get(&root_mem->css);
1212                 ret = root_mem;
1213         }
1214
1215         while (!ret) {
1216                 rcu_read_lock();
1217                 nextid = root_mem->last_scanned_child + 1;
1218                 css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css,
1219                                    &found);
1220                 if (css && css_tryget(css))
1221                         ret = container_of(css, struct mem_cgroup, css);
1222
1223                 rcu_read_unlock();
1224                 /* Updates scanning parameter */
1225                 spin_lock(&root_mem->reclaim_param_lock);
1226                 if (!css) {
1227                         /* this means start scan from ID:1 */
1228                         root_mem->last_scanned_child = 0;
1229                 } else
1230                         root_mem->last_scanned_child = found;
1231                 spin_unlock(&root_mem->reclaim_param_lock);
1232         }
1233
1234         return ret;
1235 }
1236
1237 /*
1238  * Scan the hierarchy if needed to reclaim memory. We remember the last child
1239  * we reclaimed from, so that we don't end up penalizing one child extensively
1240  * based on its position in the children list.
1241  *
1242  * root_mem is the original ancestor that we've been reclaim from.
1243  *
1244  * We give up and return to the caller when we visit root_mem twice.
1245  * (other groups can be removed while we're walking....)
1246  *
1247  * If shrink==true, for avoiding to free too much, this returns immedieately.
1248  */
1249 static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
1250                                                 struct zone *zone,
1251                                                 gfp_t gfp_mask,
1252                                                 unsigned long reclaim_options)
1253 {
1254         struct mem_cgroup *victim;
1255         int ret, total = 0;
1256         int loop = 0;
1257         bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
1258         bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
1259         bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
1260         unsigned long excess = mem_cgroup_get_excess(root_mem);
1261
1262         /* If memsw_is_minimum==1, swap-out is of-no-use. */
1263         if (root_mem->memsw_is_minimum)
1264                 noswap = true;
1265
1266         while (1) {
1267                 victim = mem_cgroup_select_victim(root_mem);
1268                 if (victim == root_mem) {
1269                         loop++;
1270                         if (loop >= 1)
1271                                 drain_all_stock_async();
1272                         if (loop >= 2) {
1273                                 /*
1274                                  * If we have not been able to reclaim
1275                                  * anything, it might because there are
1276                                  * no reclaimable pages under this hierarchy
1277                                  */
1278                                 if (!check_soft || !total) {
1279                                         css_put(&victim->css);
1280                                         break;
1281                                 }
1282                                 /*
1283                                  * We want to do more targetted reclaim.
1284                                  * excess >> 2 is not to excessive so as to
1285                                  * reclaim too much, nor too less that we keep
1286                                  * coming back to reclaim from this cgroup
1287                                  */
1288                                 if (total >= (excess >> 2) ||
1289                                         (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) {
1290                                         css_put(&victim->css);
1291                                         break;
1292                                 }
1293                         }
1294                 }
1295                 if (!mem_cgroup_local_usage(victim)) {
1296                         /* this cgroup's local usage == 0 */
1297                         css_put(&victim->css);
1298                         continue;
1299                 }
1300                 /* we use swappiness of local cgroup */
1301                 if (check_soft)
1302                         ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
1303                                 noswap, get_swappiness(victim), zone);
1304                 else
1305                         ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
1306                                                 noswap, get_swappiness(victim));
1307                 css_put(&victim->css);
1308                 /*
1309                  * At shrinking usage, we can't check we should stop here or
1310                  * reclaim more. It's depends on callers. last_scanned_child
1311                  * will work enough for keeping fairness under tree.
1312                  */
1313                 if (shrink)
1314                         return ret;
1315                 total += ret;
1316                 if (check_soft) {
1317                         if (res_counter_check_under_soft_limit(&root_mem->res))
1318                                 return total;
1319                 } else if (mem_cgroup_check_under_limit(root_mem))
1320                         return 1 + total;
1321         }
1322         return total;
1323 }
1324
1325 static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data)
1326 {
1327         int *val = (int *)data;
1328         int x;
1329         /*
1330          * Logically, we can stop scanning immediately when we find
1331          * a memcg is already locked. But condidering unlock ops and
1332          * creation/removal of memcg, scan-all is simple operation.
1333          */
1334         x = atomic_inc_return(&mem->oom_lock);
1335         *val = max(x, *val);
1336         return 0;
1337 }
1338 /*
1339  * Check OOM-Killer is already running under our hierarchy.
1340  * If someone is running, return false.
1341  */
1342 static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
1343 {
1344         int lock_count = 0;
1345
1346         mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb);
1347
1348         if (lock_count == 1)
1349                 return true;
1350         return false;
1351 }
1352
1353 static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data)
1354 {
1355         /*
1356          * When a new child is created while the hierarchy is under oom,
1357          * mem_cgroup_oom_lock() may not be called. We have to use
1358          * atomic_add_unless() here.
1359          */
1360         atomic_add_unless(&mem->oom_lock, -1, 0);
1361         return 0;
1362 }
1363
1364 static void mem_cgroup_oom_unlock(struct mem_cgroup *mem)
1365 {
1366         mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb);
1367 }
1368
1369 static DEFINE_MUTEX(memcg_oom_mutex);
1370 static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1371
1372 struct oom_wait_info {
1373         struct mem_cgroup *mem;
1374         wait_queue_t    wait;
1375 };
1376
1377 static int memcg_oom_wake_function(wait_queue_t *wait,
1378         unsigned mode, int sync, void *arg)
1379 {
1380         struct mem_cgroup *wake_mem = (struct mem_cgroup *)arg;
1381         struct oom_wait_info *oom_wait_info;
1382
1383         oom_wait_info = container_of(wait, struct oom_wait_info, wait);
1384
1385         if (oom_wait_info->mem == wake_mem)
1386                 goto wakeup;
1387         /* if no hierarchy, no match */
1388         if (!oom_wait_info->mem->use_hierarchy || !wake_mem->use_hierarchy)
1389                 return 0;
1390         /*
1391          * Both of oom_wait_info->mem and wake_mem are stable under us.
1392          * Then we can use css_is_ancestor without taking care of RCU.
1393          */
1394         if (!css_is_ancestor(&oom_wait_info->mem->css, &wake_mem->css) &&
1395             !css_is_ancestor(&wake_mem->css, &oom_wait_info->mem->css))
1396                 return 0;
1397
1398 wakeup:
1399         return autoremove_wake_function(wait, mode, sync, arg);
1400 }
1401
1402 static void memcg_wakeup_oom(struct mem_cgroup *mem)
1403 {
1404         /* for filtering, pass "mem" as argument. */
1405         __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, mem);
1406 }
1407
1408 static void memcg_oom_recover(struct mem_cgroup *mem)
1409 {
1410         if (mem && atomic_read(&mem->oom_lock))
1411                 memcg_wakeup_oom(mem);
1412 }
1413
1414 /*
1415  * try to call OOM killer. returns false if we should exit memory-reclaim loop.
1416  */
1417 bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
1418 {
1419         struct oom_wait_info owait;
1420         bool locked, need_to_kill;
1421
1422         owait.mem = mem;
1423         owait.wait.flags = 0;
1424         owait.wait.func = memcg_oom_wake_function;
1425         owait.wait.private = current;
1426         INIT_LIST_HEAD(&owait.wait.task_list);
1427         need_to_kill = true;
1428         /* At first, try to OOM lock hierarchy under mem.*/
1429         mutex_lock(&memcg_oom_mutex);
1430         locked = mem_cgroup_oom_lock(mem);
1431         /*
1432          * Even if signal_pending(), we can't quit charge() loop without
1433          * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
1434          * under OOM is always welcomed, use TASK_KILLABLE here.
1435          */
1436         prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
1437         if (!locked || mem->oom_kill_disable)
1438                 need_to_kill = false;
1439         if (locked)
1440                 mem_cgroup_oom_notify(mem);
1441         mutex_unlock(&memcg_oom_mutex);
1442
1443         if (need_to_kill) {
1444                 finish_wait(&memcg_oom_waitq, &owait.wait);
1445                 mem_cgroup_out_of_memory(mem, mask);
1446         } else {
1447                 schedule();
1448                 finish_wait(&memcg_oom_waitq, &owait.wait);
1449         }
1450         mutex_lock(&memcg_oom_mutex);
1451         mem_cgroup_oom_unlock(mem);
1452         memcg_wakeup_oom(mem);
1453         mutex_unlock(&memcg_oom_mutex);
1454
1455         if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
1456                 return false;
1457         /* Give chance to dying process */
1458         schedule_timeout(1);
1459         return true;
1460 }
1461
1462 /*
1463  * Currently used to update mapped file statistics, but the routine can be
1464  * generalized to update other statistics as well.
1465  */
1466 void mem_cgroup_update_file_mapped(struct page *page, int val)
1467 {
1468         struct mem_cgroup *mem;
1469         struct page_cgroup *pc;
1470
1471         pc = lookup_page_cgroup(page);
1472         if (unlikely(!pc))
1473                 return;
1474
1475         lock_page_cgroup(pc);
1476         mem = pc->mem_cgroup;
1477         if (!mem || !PageCgroupUsed(pc))
1478                 goto done;
1479
1480         /*
1481          * Preemption is already disabled. We can use __this_cpu_xxx
1482          */
1483         if (val > 0) {
1484                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1485                 SetPageCgroupFileMapped(pc);
1486         } else {
1487                 __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1488                 if (!page_mapped(page)) /* for race between dec->inc counter */
1489                         ClearPageCgroupFileMapped(pc);
1490         }
1491
1492 done:
1493         unlock_page_cgroup(pc);
1494 }
1495
1496 /*
1497  * size of first charge trial. "32" comes from vmscan.c's magic value.
1498  * TODO: maybe necessary to use big numbers in big irons.
1499  */
1500 #define CHARGE_SIZE     (32 * PAGE_SIZE)
1501 struct memcg_stock_pcp {
1502         struct mem_cgroup *cached; /* this never be root cgroup */
1503         int charge;
1504         struct work_struct work;
1505 };
1506 static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
1507 static atomic_t memcg_drain_count;
1508
1509 /*
1510  * Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed
1511  * from local stock and true is returned. If the stock is 0 or charges from a
1512  * cgroup which is not current target, returns false. This stock will be
1513  * refilled.
1514  */
1515 static bool consume_stock(struct mem_cgroup *mem)
1516 {
1517         struct memcg_stock_pcp *stock;
1518         bool ret = true;
1519
1520         stock = &get_cpu_var(memcg_stock);
1521         if (mem == stock->cached && stock->charge)
1522                 stock->charge -= PAGE_SIZE;
1523         else /* need to call res_counter_charge */
1524                 ret = false;
1525         put_cpu_var(memcg_stock);
1526         return ret;
1527 }
1528
1529 /*
1530  * Returns stocks cached in percpu to res_counter and reset cached information.
1531  */
1532 static void drain_stock(struct memcg_stock_pcp *stock)
1533 {
1534         struct mem_cgroup *old = stock->cached;
1535
1536         if (stock->charge) {
1537                 res_counter_uncharge(&old->res, stock->charge);
1538                 if (do_swap_account)
1539                         res_counter_uncharge(&old->memsw, stock->charge);
1540         }
1541         stock->cached = NULL;
1542         stock->charge = 0;
1543 }
1544
1545 /*
1546  * This must be called under preempt disabled or must be called by
1547  * a thread which is pinned to local cpu.
1548  */
1549 static void drain_local_stock(struct work_struct *dummy)
1550 {
1551         struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
1552         drain_stock(stock);
1553 }
1554
1555 /*
1556  * Cache charges(val) which is from res_counter, to local per_cpu area.
1557  * This will be consumed by consume_stock() function, later.
1558  */
1559 static void refill_stock(struct mem_cgroup *mem, int val)
1560 {
1561         struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
1562
1563         if (stock->cached != mem) { /* reset if necessary */
1564                 drain_stock(stock);
1565                 stock->cached = mem;
1566         }
1567         stock->charge += val;
1568         put_cpu_var(memcg_stock);
1569 }
1570
1571 /*
1572  * Tries to drain stocked charges in other cpus. This function is asynchronous
1573  * and just put a work per cpu for draining localy on each cpu. Caller can
1574  * expects some charges will be back to res_counter later but cannot wait for
1575  * it.
1576  */
1577 static void drain_all_stock_async(void)
1578 {
1579         int cpu;
1580         /* This function is for scheduling "drain" in asynchronous way.
1581          * The result of "drain" is not directly handled by callers. Then,
1582          * if someone is calling drain, we don't have to call drain more.
1583          * Anyway, WORK_STRUCT_PENDING check in queue_work_on() will catch if
1584          * there is a race. We just do loose check here.
1585          */
1586         if (atomic_read(&memcg_drain_count))
1587                 return;
1588         /* Notify other cpus that system-wide "drain" is running */
1589         atomic_inc(&memcg_drain_count);
1590         get_online_cpus();
1591         for_each_online_cpu(cpu) {
1592                 struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
1593                 schedule_work_on(cpu, &stock->work);
1594         }
1595         put_online_cpus();
1596         atomic_dec(&memcg_drain_count);
1597         /* We don't wait for flush_work */
1598 }
1599
1600 /* This is a synchronous drain interface. */
1601 static void drain_all_stock_sync(void)
1602 {
1603         /* called when force_empty is called */
1604         atomic_inc(&memcg_drain_count);
1605         schedule_on_each_cpu(drain_local_stock);
1606         atomic_dec(&memcg_drain_count);
1607 }
1608
1609 static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb,
1610                                         unsigned long action,
1611                                         void *hcpu)
1612 {
1613         int cpu = (unsigned long)hcpu;
1614         struct memcg_stock_pcp *stock;
1615
1616         if (action != CPU_DEAD)
1617                 return NOTIFY_OK;
1618         stock = &per_cpu(memcg_stock, cpu);
1619         drain_stock(stock);
1620         return NOTIFY_OK;
1621 }
1622
1623
1624 /* See __mem_cgroup_try_charge() for details */
1625 enum {
1626         CHARGE_OK,              /* success */
1627         CHARGE_RETRY,           /* need to retry but retry is not bad */
1628         CHARGE_NOMEM,           /* we can't do more. return -ENOMEM */
1629         CHARGE_WOULDBLOCK,      /* GFP_WAIT wasn't set and no enough res. */
1630         CHARGE_OOM_DIE,         /* the current is killed because of OOM */
1631 };
1632
1633 static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
1634                                 int csize, bool oom_check)
1635 {
1636         struct mem_cgroup *mem_over_limit;
1637         struct res_counter *fail_res;
1638         unsigned long flags = 0;
1639         int ret;
1640
1641         ret = res_counter_charge(&mem->res, csize, &fail_res);
1642
1643         if (likely(!ret)) {
1644                 if (!do_swap_account)
1645                         return CHARGE_OK;
1646                 ret = res_counter_charge(&mem->memsw, csize, &fail_res);
1647                 if (likely(!ret))
1648                         return CHARGE_OK;
1649
1650                 mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
1651                 flags |= MEM_CGROUP_RECLAIM_NOSWAP;
1652         } else
1653                 mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
1654
1655         if (csize > PAGE_SIZE) /* change csize and retry */
1656                 return CHARGE_RETRY;
1657
1658         if (!(gfp_mask & __GFP_WAIT))
1659                 return CHARGE_WOULDBLOCK;
1660
1661         ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
1662                                         gfp_mask, flags);
1663         /*
1664          * try_to_free_mem_cgroup_pages() might not give us a full
1665          * picture of reclaim. Some pages are reclaimed and might be
1666          * moved to swap cache or just unmapped from the cgroup.
1667          * Check the limit again to see if the reclaim reduced the
1668          * current usage of the cgroup before giving up
1669          */
1670         if (ret || mem_cgroup_check_under_limit(mem_over_limit))
1671                 return CHARGE_RETRY;
1672
1673         /*
1674          * At task move, charge accounts can be doubly counted. So, it's
1675          * better to wait until the end of task_move if something is going on.
1676          */
1677         if (mem_cgroup_wait_acct_move(mem_over_limit))
1678                 return CHARGE_RETRY;
1679
1680         /* If we don't need to call oom-killer at el, return immediately */
1681         if (!oom_check)
1682                 return CHARGE_NOMEM;
1683         /* check OOM */
1684         if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask))
1685                 return CHARGE_OOM_DIE;
1686
1687         return CHARGE_RETRY;
1688 }
1689
1690 /*
1691  * Unlike exported interface, "oom" parameter is added. if oom==true,
1692  * oom-killer can be invoked.
1693  */
1694 static int __mem_cgroup_try_charge(struct mm_struct *mm,
1695                 gfp_t gfp_mask, struct mem_cgroup **memcg, bool oom)
1696 {
1697         int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
1698         struct mem_cgroup *mem = NULL;
1699         int ret;
1700         int csize = CHARGE_SIZE;
1701
1702         /*
1703          * Unlike gloval-vm's OOM-kill, we're not in memory shortage
1704          * in system level. So, allow to go ahead dying process in addition to
1705          * MEMDIE process.
1706          */
1707         if (unlikely(test_thread_flag(TIF_MEMDIE)
1708                      || fatal_signal_pending(current)))
1709                 goto bypass;
1710
1711         /*
1712          * We always charge the cgroup the mm_struct belongs to.
1713          * The mm_struct's mem_cgroup changes on task migration if the
1714          * thread group leader migrates. It's possible that mm is not
1715          * set, if so charge the init_mm (happens for pagecache usage).
1716          */
1717         if (!*memcg && !mm)
1718                 goto bypass;
1719 again:
1720         if (*memcg) { /* css should be a valid one */
1721                 mem = *memcg;
1722                 VM_BUG_ON(css_is_removed(&mem->css));
1723                 if (mem_cgroup_is_root(mem))
1724                         goto done;
1725                 if (consume_stock(mem))
1726                         goto done;
1727                 css_get(&mem->css);
1728         } else {
1729                 struct task_struct *p;
1730
1731                 rcu_read_lock();
1732                 p = rcu_dereference(mm->owner);
1733                 VM_BUG_ON(!p);
1734                 /*
1735                  * because we don't have task_lock(), "p" can exit while
1736                  * we're here. In that case, "mem" can point to root
1737                  * cgroup but never be NULL. (and task_struct itself is freed
1738                  * by RCU, cgroup itself is RCU safe.) Then, we have small
1739                  * risk here to get wrong cgroup. But such kind of mis-account
1740                  * by race always happens because we don't have cgroup_mutex().
1741                  * It's overkill and we allow that small race, here.
1742                  */
1743                 mem = mem_cgroup_from_task(p);
1744                 VM_BUG_ON(!mem);
1745                 if (mem_cgroup_is_root(mem)) {
1746                         rcu_read_unlock();
1747                         goto done;
1748                 }
1749                 if (consume_stock(mem)) {
1750                         /*
1751                          * It seems dagerous to access memcg without css_get().
1752                          * But considering how consume_stok works, it's not
1753                          * necessary. If consume_stock success, some charges
1754                          * from this memcg are cached on this cpu. So, we
1755                          * don't need to call css_get()/css_tryget() before
1756                          * calling consume_stock().
1757                          */
1758                         rcu_read_unlock();
1759                         goto done;
1760                 }
1761                 /* after here, we may be blocked. we need to get refcnt */
1762                 if (!css_tryget(&mem->css)) {
1763                         rcu_read_unlock();
1764                         goto again;
1765                 }
1766                 rcu_read_unlock();
1767         }
1768
1769         do {
1770                 bool oom_check;
1771
1772                 /* If killed, bypass charge */
1773                 if (fatal_signal_pending(current)) {
1774                         css_put(&mem->css);
1775                         goto bypass;
1776                 }
1777
1778                 oom_check = false;
1779                 if (oom && !nr_oom_retries) {
1780                         oom_check = true;
1781                         nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
1782                 }
1783
1784                 ret = __mem_cgroup_do_charge(mem, gfp_mask, csize, oom_check);
1785
1786                 switch (ret) {
1787                 case CHARGE_OK:
1788                         break;
1789                 case CHARGE_RETRY: /* not in OOM situation but retry */
1790                         csize = PAGE_SIZE;
1791                         css_put(&mem->css);
1792                         mem = NULL;
1793                         goto again;
1794                 case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
1795                         css_put(&mem->css);
1796                         goto nomem;
1797                 case CHARGE_NOMEM: /* OOM routine works */
1798                         if (!oom) {
1799                                 css_put(&mem->css);
1800                                 goto nomem;
1801                         }
1802                         /* If oom, we never return -ENOMEM */
1803                         nr_oom_retries--;
1804                         break;
1805                 case CHARGE_OOM_DIE: /* Killed by OOM Killer */
1806                         css_put(&mem->css);
1807                         goto bypass;
1808                 }
1809         } while (ret != CHARGE_OK);
1810
1811         if (csize > PAGE_SIZE)
1812                 refill_stock(mem, csize - PAGE_SIZE);
1813         css_put(&mem->css);
1814 done:
1815         *memcg = mem;
1816         return 0;
1817 nomem:
1818         *memcg = NULL;
1819         return -ENOMEM;
1820 bypass:
1821         *memcg = NULL;
1822         return 0;
1823 }
1824
1825 /*
1826  * Somemtimes we have to undo a charge we got by try_charge().
1827  * This function is for that and do uncharge, put css's refcnt.
1828  * gotten by try_charge().
1829  */
1830 static void __mem_cgroup_cancel_charge(struct mem_cgroup *mem,
1831                                                         unsigned long count)
1832 {
1833         if (!mem_cgroup_is_root(mem)) {
1834                 res_counter_uncharge(&mem->res, PAGE_SIZE * count);
1835                 if (do_swap_account)
1836                         res_counter_uncharge(&mem->memsw, PAGE_SIZE * count);
1837         }
1838 }
1839
1840 static void mem_cgroup_cancel_charge(struct mem_cgroup *mem)
1841 {
1842         __mem_cgroup_cancel_charge(mem, 1);
1843 }
1844
1845 /*
1846  * A helper function to get mem_cgroup from ID. must be called under
1847  * rcu_read_lock(). The caller must check css_is_removed() or some if
1848  * it's concern. (dropping refcnt from swap can be called against removed
1849  * memcg.)
1850  */
1851 static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
1852 {
1853         struct cgroup_subsys_state *css;
1854
1855         /* ID 0 is unused ID */
1856         if (!id)
1857                 return NULL;
1858         css = css_lookup(&mem_cgroup_subsys, id);
1859         if (!css)
1860                 return NULL;
1861         return container_of(css, struct mem_cgroup, css);
1862 }
1863
1864 struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
1865 {
1866         struct mem_cgroup *mem = NULL;
1867         struct page_cgroup *pc;
1868         unsigned short id;
1869         swp_entry_t ent;
1870
1871         VM_BUG_ON(!PageLocked(page));
1872
1873         pc = lookup_page_cgroup(page);
1874         lock_page_cgroup(pc);
1875         if (PageCgroupUsed(pc)) {
1876                 mem = pc->mem_cgroup;
1877                 if (mem && !css_tryget(&mem->css))
1878                         mem = NULL;
1879         } else if (PageSwapCache(page)) {
1880                 ent.val = page_private(page);
1881                 id = lookup_swap_cgroup(ent);
1882                 rcu_read_lock();
1883                 mem = mem_cgroup_lookup(id);
1884                 if (mem && !css_tryget(&mem->css))
1885                         mem = NULL;
1886                 rcu_read_unlock();
1887         }
1888         unlock_page_cgroup(pc);
1889         return mem;
1890 }
1891
1892 /*
1893  * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
1894  * USED state. If already USED, uncharge and return.
1895  */
1896
1897 static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
1898                                      struct page_cgroup *pc,
1899                                      enum charge_type ctype)
1900 {
1901         /* try_charge() can return NULL to *memcg, taking care of it. */
1902         if (!mem)
1903                 return;
1904
1905         lock_page_cgroup(pc);
1906         if (unlikely(PageCgroupUsed(pc))) {
1907                 unlock_page_cgroup(pc);
1908                 mem_cgroup_cancel_charge(mem);
1909                 return;
1910         }
1911
1912         pc->mem_cgroup = mem;
1913         /*
1914          * We access a page_cgroup asynchronously without lock_page_cgroup().
1915          * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
1916          * is accessed after testing USED bit. To make pc->mem_cgroup visible
1917          * before USED bit, we need memory barrier here.
1918          * See mem_cgroup_add_lru_list(), etc.
1919          */
1920         smp_wmb();
1921         switch (ctype) {
1922         case MEM_CGROUP_CHARGE_TYPE_CACHE:
1923         case MEM_CGROUP_CHARGE_TYPE_SHMEM:
1924                 SetPageCgroupCache(pc);
1925                 SetPageCgroupUsed(pc);
1926                 break;
1927         case MEM_CGROUP_CHARGE_TYPE_MAPPED:
1928                 ClearPageCgroupCache(pc);
1929                 SetPageCgroupUsed(pc);
1930                 break;
1931         default:
1932                 break;
1933         }
1934
1935         mem_cgroup_charge_statistics(mem, pc, true);
1936
1937         unlock_page_cgroup(pc);
1938         /*
1939          * "charge_statistics" updated event counter. Then, check it.
1940          * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
1941          * if they exceeds softlimit.
1942          */
1943         memcg_check_events(mem, pc->page);
1944 }
1945
1946 /**
1947  * __mem_cgroup_move_account - move account of the page
1948  * @pc: page_cgroup of the page.
1949  * @from: mem_cgroup which the page is moved from.
1950  * @to: mem_cgroup which the page is moved to. @from != @to.
1951  * @uncharge: whether we should call uncharge and css_put against @from.
1952  *
1953  * The caller must confirm following.
1954  * - page is not on LRU (isolate_page() is useful.)
1955  * - the pc is locked, used, and ->mem_cgroup points to @from.
1956  *
1957  * This function doesn't do "charge" nor css_get to new cgroup. It should be
1958  * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
1959  * true, this function does "uncharge" from old cgroup, but it doesn't if
1960  * @uncharge is false, so a caller should do "uncharge".
1961  */
1962
1963 static void __mem_cgroup_move_account(struct page_cgroup *pc,
1964         struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
1965 {
1966         VM_BUG_ON(from == to);
1967         VM_BUG_ON(PageLRU(pc->page));
1968         VM_BUG_ON(!PageCgroupLocked(pc));
1969         VM_BUG_ON(!PageCgroupUsed(pc));
1970         VM_BUG_ON(pc->mem_cgroup != from);
1971
1972         if (PageCgroupFileMapped(pc)) {
1973                 /* Update mapped_file data for mem_cgroup */
1974                 preempt_disable();
1975                 __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1976                 __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
1977                 preempt_enable();
1978         }
1979         mem_cgroup_charge_statistics(from, pc, false);
1980         if (uncharge)
1981                 /* This is not "cancel", but cancel_charge does all we need. */
1982                 mem_cgroup_cancel_charge(from);
1983
1984         /* caller should have done css_get */
1985         pc->mem_cgroup = to;
1986         mem_cgroup_charge_statistics(to, pc, true);
1987         /*
1988          * We charges against "to" which may not have any tasks. Then, "to"
1989          * can be under rmdir(). But in current implementation, caller of
1990          * this function is just force_empty() and move charge, so it's
1991          * garanteed that "to" is never removed. So, we don't check rmdir
1992          * status here.
1993          */
1994 }
1995
1996 /*
1997  * check whether the @pc is valid for moving account and call
1998  * __mem_cgroup_move_account()
1999  */
2000 static int mem_cgroup_move_account(struct page_cgroup *pc,
2001                 struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
2002 {
2003         int ret = -EINVAL;
2004         lock_page_cgroup(pc);
2005         if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
2006                 __mem_cgroup_move_account(pc, from, to, uncharge);
2007                 ret = 0;
2008         }
2009         unlock_page_cgroup(pc);
2010         /*
2011          * check events
2012          */
2013         memcg_check_events(to, pc->page);
2014         memcg_check_events(from, pc->page);
2015         return ret;
2016 }
2017
2018 /*
2019  * move charges to its parent.
2020  */
2021
2022 static int mem_cgroup_move_parent(struct page_cgroup *pc,
2023                                   struct mem_cgroup *child,
2024                                   gfp_t gfp_mask)
2025 {
2026         struct page *page = pc->page;
2027         struct cgroup *cg = child->css.cgroup;
2028         struct cgroup *pcg = cg->parent;
2029         struct mem_cgroup *parent;
2030         int ret;
2031
2032         /* Is ROOT ? */
2033         if (!pcg)
2034                 return -EINVAL;
2035
2036         ret = -EBUSY;
2037         if (!get_page_unless_zero(page))
2038                 goto out;
2039         if (isolate_lru_page(page))
2040                 goto put;
2041
2042         parent = mem_cgroup_from_cont(pcg);
2043         ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
2044         if (ret || !parent)
2045                 goto put_back;
2046
2047         ret = mem_cgroup_move_account(pc, child, parent, true);
2048         if (ret)
2049                 mem_cgroup_cancel_charge(parent);
2050 put_back:
2051         putback_lru_page(page);
2052 put:
2053         put_page(page);
2054 out:
2055         return ret;
2056 }
2057
2058 /*
2059  * Charge the memory controller for page usage.
2060  * Return
2061  * 0 if the charge was successful
2062  * < 0 if the cgroup is over its limit
2063  */
2064 static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
2065                                 gfp_t gfp_mask, enum charge_type ctype)
2066 {
2067         struct mem_cgroup *mem = NULL;
2068         struct page_cgroup *pc;
2069         int ret;
2070
2071         pc = lookup_page_cgroup(page);
2072         /* can happen at boot */
2073         if (unlikely(!pc))
2074                 return 0;
2075         prefetchw(pc);
2076
2077         ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
2078         if (ret || !mem)
2079                 return ret;
2080
2081         __mem_cgroup_commit_charge(mem, pc, ctype);
2082         return 0;
2083 }
2084
2085 int mem_cgroup_newpage_charge(struct page *page,
2086                               struct mm_struct *mm, gfp_t gfp_mask)
2087 {
2088         if (mem_cgroup_disabled())
2089                 return 0;
2090         if (PageCompound(page))
2091                 return 0;
2092         /*
2093          * If already mapped, we don't have to account.
2094          * If page cache, page->mapping has address_space.
2095          * But page->mapping may have out-of-use anon_vma pointer,
2096          * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
2097          * is NULL.
2098          */
2099         if (page_mapped(page) || (page->mapping && !PageAnon(page)))
2100                 return 0;
2101         if (unlikely(!mm))
2102                 mm = &init_mm;
2103         return mem_cgroup_charge_common(page, mm, gfp_mask,
2104                                 MEM_CGROUP_CHARGE_TYPE_MAPPED);
2105 }
2106
2107 static void
2108 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2109                                         enum charge_type ctype);
2110
2111 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
2112                                 gfp_t gfp_mask)
2113 {
2114         int ret;
2115
2116         if (mem_cgroup_disabled())
2117                 return 0;
2118         if (PageCompound(page))
2119                 return 0;
2120         /*
2121          * Corner case handling. This is called from add_to_page_cache()
2122          * in usual. But some FS (shmem) precharges this page before calling it
2123          * and call add_to_page_cache() with GFP_NOWAIT.
2124          *
2125          * For GFP_NOWAIT case, the page may be pre-charged before calling
2126          * add_to_page_cache(). (See shmem.c) check it here and avoid to call
2127          * charge twice. (It works but has to pay a bit larger cost.)
2128          * And when the page is SwapCache, it should take swap information
2129          * into account. This is under lock_page() now.
2130          */
2131         if (!(gfp_mask & __GFP_WAIT)) {
2132                 struct page_cgroup *pc;
2133
2134                 pc = lookup_page_cgroup(page);
2135                 if (!pc)
2136                         return 0;
2137                 lock_page_cgroup(pc);
2138                 if (PageCgroupUsed(pc)) {
2139                         unlock_page_cgroup(pc);
2140                         return 0;
2141                 }
2142                 unlock_page_cgroup(pc);
2143         }
2144
2145         if (unlikely(!mm))
2146                 mm = &init_mm;
2147
2148         if (page_is_file_cache(page))
2149                 return mem_cgroup_charge_common(page, mm, gfp_mask,
2150                                 MEM_CGROUP_CHARGE_TYPE_CACHE);
2151
2152         /* shmem */
2153         if (PageSwapCache(page)) {
2154                 struct mem_cgroup *mem = NULL;
2155
2156                 ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2157                 if (!ret)
2158                         __mem_cgroup_commit_charge_swapin(page, mem,
2159                                         MEM_CGROUP_CHARGE_TYPE_SHMEM);
2160         } else
2161                 ret = mem_cgroup_charge_common(page, mm, gfp_mask,
2162                                         MEM_CGROUP_CHARGE_TYPE_SHMEM);
2163
2164         return ret;
2165 }
2166
2167 /*
2168  * While swap-in, try_charge -> commit or cancel, the page is locked.
2169  * And when try_charge() successfully returns, one refcnt to memcg without
2170  * struct page_cgroup is acquired. This refcnt will be consumed by
2171  * "commit()" or removed by "cancel()"
2172  */
2173 int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
2174                                  struct page *page,
2175                                  gfp_t mask, struct mem_cgroup **ptr)
2176 {
2177         struct mem_cgroup *mem;
2178         int ret;
2179
2180         if (mem_cgroup_disabled())
2181                 return 0;
2182
2183         if (!do_swap_account)
2184                 goto charge_cur_mm;
2185         /*
2186          * A racing thread's fault, or swapoff, may have already updated
2187          * the pte, and even removed page from swap cache: in those cases
2188          * do_swap_page()'s pte_same() test will fail; but there's also a
2189          * KSM case which does need to charge the page.
2190          */
2191         if (!PageSwapCache(page))
2192                 goto charge_cur_mm;
2193         mem = try_get_mem_cgroup_from_page(page);
2194         if (!mem)
2195                 goto charge_cur_mm;
2196         *ptr = mem;
2197         ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
2198         css_put(&mem->css);
2199         return ret;
2200 charge_cur_mm:
2201         if (unlikely(!mm))
2202                 mm = &init_mm;
2203         return __mem_cgroup_try_charge(mm, mask, ptr, true);
2204 }
2205
2206 static void
2207 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2208                                         enum charge_type ctype)
2209 {
2210         struct page_cgroup *pc;
2211
2212         if (mem_cgroup_disabled())
2213                 return;
2214         if (!ptr)
2215                 return;
2216         cgroup_exclude_rmdir(&ptr->css);
2217         pc = lookup_page_cgroup(page);
2218         mem_cgroup_lru_del_before_commit_swapcache(page);
2219         __mem_cgroup_commit_charge(ptr, pc, ctype);
2220         mem_cgroup_lru_add_after_commit_swapcache(page);
2221         /*
2222          * Now swap is on-memory. This means this page may be
2223          * counted both as mem and swap....double count.
2224          * Fix it by uncharging from memsw. Basically, this SwapCache is stable
2225          * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
2226          * may call delete_from_swap_cache() before reach here.
2227          */
2228         if (do_swap_account && PageSwapCache(page)) {
2229                 swp_entry_t ent = {.val = page_private(page)};
2230                 unsigned short id;
2231                 struct mem_cgroup *memcg;
2232
2233                 id = swap_cgroup_record(ent, 0);
2234                 rcu_read_lock();
2235                 memcg = mem_cgroup_lookup(id);
2236                 if (memcg) {
2237                         /*
2238                          * This recorded memcg can be obsolete one. So, avoid
2239                          * calling css_tryget
2240                          */
2241                         if (!mem_cgroup_is_root(memcg))
2242                                 res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2243                         mem_cgroup_swap_statistics(memcg, false);
2244                         mem_cgroup_put(memcg);
2245                 }
2246                 rcu_read_unlock();
2247         }
2248         /*
2249          * At swapin, we may charge account against cgroup which has no tasks.
2250          * So, rmdir()->pre_destroy() can be called while we do this charge.
2251          * In that case, we need to call pre_destroy() again. check it here.
2252          */
2253         cgroup_release_and_wakeup_rmdir(&ptr->css);
2254 }
2255
2256 void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
2257 {
2258         __mem_cgroup_commit_charge_swapin(page, ptr,
2259                                         MEM_CGROUP_CHARGE_TYPE_MAPPED);
2260 }
2261
2262 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
2263 {
2264         if (mem_cgroup_disabled())
2265                 return;
2266         if (!mem)
2267                 return;
2268         mem_cgroup_cancel_charge(mem);
2269 }
2270
2271 static void
2272 __do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype)
2273 {
2274         struct memcg_batch_info *batch = NULL;
2275         bool uncharge_memsw = true;
2276         /* If swapout, usage of swap doesn't decrease */
2277         if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2278                 uncharge_memsw = false;
2279
2280         batch = &current->memcg_batch;
2281         /*
2282          * In usual, we do css_get() when we remember memcg pointer.
2283          * But in this case, we keep res->usage until end of a series of
2284          * uncharges. Then, it's ok to ignore memcg's refcnt.
2285          */
2286         if (!batch->memcg)
2287                 batch->memcg = mem;
2288         /*
2289          * do_batch > 0 when unmapping pages or inode invalidate/truncate.
2290          * In those cases, all pages freed continously can be expected to be in
2291          * the same cgroup and we have chance to coalesce uncharges.
2292          * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
2293          * because we want to do uncharge as soon as possible.
2294          */
2295
2296         if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
2297                 goto direct_uncharge;
2298
2299         /*
2300          * In typical case, batch->memcg == mem. This means we can
2301          * merge a series of uncharges to an uncharge of res_counter.
2302          * If not, we uncharge res_counter ony by one.
2303          */
2304         if (batch->memcg != mem)
2305                 goto direct_uncharge;
2306         /* remember freed charge and uncharge it later */
2307         batch->bytes += PAGE_SIZE;
2308         if (uncharge_memsw)
2309                 batch->memsw_bytes += PAGE_SIZE;
2310         return;
2311 direct_uncharge:
2312         res_counter_uncharge(&mem->res, PAGE_SIZE);
2313         if (uncharge_memsw)
2314                 res_counter_uncharge(&mem->memsw, PAGE_SIZE);
2315         if (unlikely(batch->memcg != mem))
2316                 memcg_oom_recover(mem);
2317         return;
2318 }
2319
2320 /*
2321  * uncharge if !page_mapped(page)
2322  */
2323 static struct mem_cgroup *
2324 __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
2325 {
2326         struct page_cgroup *pc;
2327         struct mem_cgroup *mem = NULL;
2328
2329         if (mem_cgroup_disabled())
2330                 return NULL;
2331
2332         if (PageSwapCache(page))
2333                 return NULL;
2334
2335         /*
2336          * Check if our page_cgroup is valid
2337          */
2338         pc = lookup_page_cgroup(page);
2339         if (unlikely(!pc || !PageCgroupUsed(pc)))
2340                 return NULL;
2341
2342         lock_page_cgroup(pc);
2343
2344         mem = pc->mem_cgroup;
2345
2346         if (!PageCgroupUsed(pc))
2347                 goto unlock_out;
2348
2349         switch (ctype) {
2350         case MEM_CGROUP_CHARGE_TYPE_MAPPED:
2351         case MEM_CGROUP_CHARGE_TYPE_DROP:
2352                 /* See mem_cgroup_prepare_migration() */
2353                 if (page_mapped(page) || PageCgroupMigration(pc))
2354                         goto unlock_out;
2355                 break;
2356         case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
2357                 if (!PageAnon(page)) {  /* Shared memory */
2358                         if (page->mapping && !page_is_file_cache(page))
2359                                 goto unlock_out;
2360                 } else if (page_mapped(page)) /* Anon */
2361                                 goto unlock_out;
2362                 break;
2363         default:
2364                 break;
2365         }
2366
2367         mem_cgroup_charge_statistics(mem, pc, false);
2368
2369         ClearPageCgroupUsed(pc);
2370         /*
2371          * pc->mem_cgroup is not cleared here. It will be accessed when it's
2372          * freed from LRU. This is safe because uncharged page is expected not
2373          * to be reused (freed soon). Exception is SwapCache, it's handled by
2374          * special functions.
2375          */
2376
2377         unlock_page_cgroup(pc);
2378         /*
2379          * even after unlock, we have mem->res.usage here and this memcg
2380          * will never be freed.
2381          */
2382         memcg_check_events(mem, page);
2383         if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
2384                 mem_cgroup_swap_statistics(mem, true);
2385                 mem_cgroup_get(mem);
2386         }
2387         if (!mem_cgroup_is_root(mem))
2388                 __do_uncharge(mem, ctype);
2389
2390         return mem;
2391
2392 unlock_out:
2393         unlock_page_cgroup(pc);
2394         return NULL;
2395 }
2396
2397 void mem_cgroup_uncharge_page(struct page *page)
2398 {
2399         /* early check. */
2400         if (page_mapped(page))
2401                 return;
2402         if (page->mapping && !PageAnon(page))
2403                 return;
2404         __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
2405 }
2406
2407 void mem_cgroup_uncharge_cache_page(struct page *page)
2408 {
2409         VM_BUG_ON(page_mapped(page));
2410         VM_BUG_ON(page->mapping);
2411         __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
2412 }
2413
2414 /*
2415  * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
2416  * In that cases, pages are freed continuously and we can expect pages
2417  * are in the same memcg. All these calls itself limits the number of
2418  * pages freed at once, then uncharge_start/end() is called properly.
2419  * This may be called prural(2) times in a context,
2420  */
2421
2422 void mem_cgroup_uncharge_start(void)
2423 {
2424         current->memcg_batch.do_batch++;
2425         /* We can do nest. */
2426         if (current->memcg_batch.do_batch == 1) {
2427                 current->memcg_batch.memcg = NULL;
2428                 current->memcg_batch.bytes = 0;
2429                 current->memcg_batch.memsw_bytes = 0;
2430         }
2431 }
2432
2433 void mem_cgroup_uncharge_end(void)
2434 {
2435         struct memcg_batch_info *batch = &current->memcg_batch;
2436
2437         if (!batch->do_batch)
2438                 return;
2439
2440         batch->do_batch--;
2441         if (batch->do_batch) /* If stacked, do nothing. */
2442                 return;
2443
2444         if (!batch->memcg)
2445                 return;
2446         /*
2447          * This "batch->memcg" is valid without any css_get/put etc...
2448          * bacause we hide charges behind us.
2449          */
2450         if (batch->bytes)
2451                 res_counter_uncharge(&batch->memcg->res, batch->bytes);
2452         if (batch->memsw_bytes)
2453                 res_counter_uncharge(&batch->memcg->memsw, batch->memsw_bytes);
2454         memcg_oom_recover(batch->memcg);
2455         /* forget this pointer (for sanity check) */
2456         batch->memcg = NULL;
2457 }
2458
2459 #ifdef CONFIG_SWAP
2460 /*
2461  * called after __delete_from_swap_cache() and drop "page" account.
2462  * memcg information is recorded to swap_cgroup of "ent"
2463  */
2464 void
2465 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
2466 {
2467         struct mem_cgroup *memcg;
2468         int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
2469
2470         if (!swapout) /* this was a swap cache but the swap is unused ! */
2471                 ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
2472
2473         memcg = __mem_cgroup_uncharge_common(page, ctype);
2474
2475         /*
2476          * record memcg information,  if swapout && memcg != NULL,
2477          * mem_cgroup_get() was called in uncharge().
2478          */
2479         if (do_swap_account && swapout && memcg)
2480                 swap_cgroup_record(ent, css_id(&memcg->css));
2481 }
2482 #endif
2483
2484 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2485 /*
2486  * called from swap_entry_free(). remove record in swap_cgroup and
2487  * uncharge "memsw" account.
2488  */
2489 void mem_cgroup_uncharge_swap(swp_entry_t ent)
2490 {
2491         struct mem_cgroup *memcg;
2492         unsigned short id;
2493
2494         if (!do_swap_account)
2495                 return;
2496
2497         id = swap_cgroup_record(ent, 0);
2498         rcu_read_lock();
2499         memcg = mem_cgroup_lookup(id);
2500         if (memcg) {
2501                 /*
2502                  * We uncharge this because swap is freed.
2503                  * This memcg can be obsolete one. We avoid calling css_tryget
2504                  */
2505                 if (!mem_cgroup_is_root(memcg))
2506                         res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2507                 mem_cgroup_swap_statistics(memcg, false);
2508                 mem_cgroup_put(memcg);
2509         }
2510         rcu_read_unlock();
2511 }
2512
2513 /**
2514  * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
2515  * @entry: swap entry to be moved
2516  * @from:  mem_cgroup which the entry is moved from
2517  * @to:  mem_cgroup which the entry is moved to
2518  * @need_fixup: whether we should fixup res_counters and refcounts.
2519  *
2520  * It succeeds only when the swap_cgroup's record for this entry is the same
2521  * as the mem_cgroup's id of @from.
2522  *
2523  * Returns 0 on success, -EINVAL on failure.
2524  *
2525  * The caller must have charged to @to, IOW, called res_counter_charge() about
2526  * both res and memsw, and called css_get().
2527  */
2528 static int mem_cgroup_move_swap_account(swp_entry_t entry,
2529                 struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2530 {
2531         unsigned short old_id, new_id;
2532
2533         old_id = css_id(&from->css);
2534         new_id = css_id(&to->css);
2535
2536         if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
2537                 mem_cgroup_swap_statistics(from, false);
2538                 mem_cgroup_swap_statistics(to, true);
2539                 /*
2540                  * This function is only called from task migration context now.
2541                  * It postpones res_counter and refcount handling till the end
2542                  * of task migration(mem_cgroup_clear_mc()) for performance
2543                  * improvement. But we cannot postpone mem_cgroup_get(to)
2544                  * because if the process that has been moved to @to does
2545                  * swap-in, the refcount of @to might be decreased to 0.
2546                  */
2547                 mem_cgroup_get(to);
2548                 if (need_fixup) {
2549                         if (!mem_cgroup_is_root(from))
2550                                 res_counter_uncharge(&from->memsw, PAGE_SIZE);
2551                         mem_cgroup_put(from);
2552                         /*
2553                          * we charged both to->res and to->memsw, so we should
2554                          * uncharge to->res.
2555                          */
2556                         if (!mem_cgroup_is_root(to))
2557                                 res_counter_uncharge(&to->res, PAGE_SIZE);
2558                 }
2559                 return 0;
2560         }
2561         return -EINVAL;
2562 }
2563 #else
2564 static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
2565                 struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2566 {
2567         return -EINVAL;
2568 }
2569 #endif
2570
2571 /*
2572  * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
2573  * page belongs to.
2574  */
2575 int mem_cgroup_prepare_migration(struct page *page,
2576         struct page *newpage, struct mem_cgroup **ptr)
2577 {
2578         struct page_cgroup *pc;
2579         struct mem_cgroup *mem = NULL;
2580         enum charge_type ctype;
2581         int ret = 0;
2582
2583         if (mem_cgroup_disabled())
2584                 return 0;
2585
2586         pc = lookup_page_cgroup(page);
2587         lock_page_cgroup(pc);
2588         if (PageCgroupUsed(pc)) {
2589                 mem = pc->mem_cgroup;
2590                 css_get(&mem->css);
2591                 /*
2592                  * At migrating an anonymous page, its mapcount goes down
2593                  * to 0 and uncharge() will be called. But, even if it's fully
2594                  * unmapped, migration may fail and this page has to be
2595                  * charged again. We set MIGRATION flag here and delay uncharge
2596                  * until end_migration() is called
2597                  *
2598                  * Corner Case Thinking
2599                  * A)
2600                  * When the old page was mapped as Anon and it's unmap-and-freed
2601                  * while migration was ongoing.
2602                  * If unmap finds the old page, uncharge() of it will be delayed
2603                  * until end_migration(). If unmap finds a new page, it's
2604                  * uncharged when it make mapcount to be 1->0. If unmap code
2605                  * finds swap_migration_entry, the new page will not be mapped
2606                  * and end_migration() will find it(mapcount==0).
2607                  *
2608                  * B)
2609                  * When the old page was mapped but migraion fails, the kernel
2610                  * remaps it. A charge for it is kept by MIGRATION flag even
2611                  * if mapcount goes down to 0. We can do remap successfully
2612                  * without charging it again.
2613                  *
2614                  * C)
2615                  * The "old" page is under lock_page() until the end of
2616                  * migration, so, the old page itself will not be swapped-out.
2617                  * If the new page is swapped out before end_migraton, our
2618                  * hook to usual swap-out path will catch the event.
2619                  */
2620                 if (PageAnon(page))
2621                         SetPageCgroupMigration(pc);
2622         }
2623         unlock_page_cgroup(pc);
2624         /*
2625          * If the page is not charged at this point,
2626          * we return here.
2627          */
2628         if (!mem)
2629                 return 0;
2630
2631         *ptr = mem;
2632         ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false);
2633         css_put(&mem->css);/* drop extra refcnt */
2634         if (ret || *ptr == NULL) {
2635                 if (PageAnon(page)) {
2636                         lock_page_cgroup(pc);
2637                         ClearPageCgroupMigration(pc);
2638                         unlock_page_cgroup(pc);
2639                         /*
2640                          * The old page may be fully unmapped while we kept it.
2641                          */
2642                         mem_cgroup_uncharge_page(page);
2643                 }
2644                 return -ENOMEM;
2645         }
2646         /*
2647          * We charge new page before it's used/mapped. So, even if unlock_page()
2648          * is called before end_migration, we can catch all events on this new
2649          * page. In the case new page is migrated but not remapped, new page's
2650          * mapcount will be finally 0 and we call uncharge in end_migration().
2651          */
2652         pc = lookup_page_cgroup(newpage);
2653         if (PageAnon(page))
2654                 ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
2655         else if (page_is_file_cache(page))
2656                 ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
2657         else
2658                 ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
2659         __mem_cgroup_commit_charge(mem, pc, ctype);
2660         return ret;
2661 }
2662
2663 /* remove redundant charge if migration failed*/
2664 void mem_cgroup_end_migration(struct mem_cgroup *mem,
2665         struct page *oldpage, struct page *newpage)
2666 {
2667         struct page *used, *unused;
2668         struct page_cgroup *pc;
2669
2670         if (!mem)
2671                 return;
2672         /* blocks rmdir() */
2673         cgroup_exclude_rmdir(&mem->css);
2674         /* at migration success, oldpage->mapping is NULL. */
2675         if (oldpage->mapping) {
2676                 used = oldpage;
2677                 unused = newpage;
2678         } else {
2679                 used = newpage;
2680                 unused = oldpage;
2681         }
2682         /*
2683          * We disallowed uncharge of pages under migration because mapcount
2684          * of the page goes down to zero, temporarly.
2685          * Clear the flag and check the page should be charged.
2686          */
2687         pc = lookup_page_cgroup(oldpage);
2688         lock_page_cgroup(pc);
2689         ClearPageCgroupMigration(pc);
2690         unlock_page_cgroup(pc);
2691
2692         __mem_cgroup_uncharge_common(unused, MEM_CGROUP_CHARGE_TYPE_FORCE);
2693
2694         /*
2695          * If a page is a file cache, radix-tree replacement is very atomic
2696          * and we can skip this check. When it was an Anon page, its mapcount
2697          * goes down to 0. But because we added MIGRATION flage, it's not
2698          * uncharged yet. There are several case but page->mapcount check
2699          * and USED bit check in mem_cgroup_uncharge_page() will do enough
2700          * check. (see prepare_charge() also)
2701          */
2702         if (PageAnon(used))
2703                 mem_cgroup_uncharge_page(used);
2704         /*
2705          * At migration, we may charge account against cgroup which has no
2706          * tasks.
2707          * So, rmdir()->pre_destroy() can be called while we do this charge.
2708          * In that case, we need to call pre_destroy() again. check it here.
2709          */
2710         cgroup_release_and_wakeup_rmdir(&mem->css);
2711 }
2712
2713 /*
2714  * A call to try to shrink memory usage on charge failure at shmem's swapin.
2715  * Calling hierarchical_reclaim is not enough because we should update
2716  * last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM.
2717  * Moreover considering hierarchy, we should reclaim from the mem_over_limit,
2718  * not from the memcg which this page would be charged to.
2719  * try_charge_swapin does all of these works properly.
2720  */
2721 int mem_cgroup_shmem_charge_fallback(struct page *page,
2722                             struct mm_struct *mm,
2723                             gfp_t gfp_mask)
2724 {
2725         struct mem_cgroup *mem = NULL;
2726         int ret;
2727
2728         if (mem_cgroup_disabled())
2729                 return 0;
2730
2731         ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2732         if (!ret)
2733                 mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */
2734
2735         return ret;
2736 }
2737
2738 static DEFINE_MUTEX(set_limit_mutex);
2739
2740 static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
2741                                 unsigned long long val)
2742 {
2743         int retry_count;
2744         u64 memswlimit, memlimit;
2745         int ret = 0;
2746         int children = mem_cgroup_count_children(memcg);
2747         u64 curusage, oldusage;
2748         int enlarge;
2749
2750         /*
2751          * For keeping hierarchical_reclaim simple, how long we should retry
2752          * is depends on callers. We set our retry-count to be function
2753          * of # of children which we should visit in this loop.
2754          */
2755         retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
2756
2757         oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
2758
2759         enlarge = 0;
2760         while (retry_count) {
2761                 if (signal_pending(current)) {
2762                         ret = -EINTR;
2763                         break;
2764                 }
2765                 /*
2766                  * Rather than hide all in some function, I do this in
2767                  * open coded manner. You see what this really does.
2768                  * We have to guarantee mem->res.limit < mem->memsw.limit.
2769                  */
2770                 mutex_lock(&set_limit_mutex);
2771                 memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
2772                 if (memswlimit < val) {
2773                         ret = -EINVAL;
2774                         mutex_unlock(&set_limit_mutex);
2775                         break;
2776                 }
2777
2778                 memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
2779                 if (memlimit < val)
2780                         enlarge = 1;
2781
2782                 ret = res_counter_set_limit(&memcg->res, val);
2783                 if (!ret) {
2784                         if (memswlimit == val)
2785                                 memcg->memsw_is_minimum = true;
2786                         else
2787                                 memcg->memsw_is_minimum = false;
2788                 }
2789                 mutex_unlock(&set_limit_mutex);
2790
2791                 if (!ret)
2792                         break;
2793
2794                 mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
2795                                                 MEM_CGROUP_RECLAIM_SHRINK);
2796                 curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
2797                 /* Usage is reduced ? */
2798                 if (curusage >= oldusage)
2799                         retry_count--;
2800                 else
2801                         oldusage = curusage;
2802         }
2803         if (!ret && enlarge)
2804                 memcg_oom_recover(memcg);
2805
2806         return ret;
2807 }
2808
2809 static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
2810                                         unsigned long long val)
2811 {
2812         int retry_count;
2813         u64 memlimit, memswlimit, oldusage, curusage;
2814         int children = mem_cgroup_count_children(memcg);
2815         int ret = -EBUSY;
2816         int enlarge = 0;
2817
2818         /* see mem_cgroup_resize_res_limit */
2819         retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
2820         oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
2821         while (retry_count) {
2822                 if (signal_pending(current)) {
2823                         ret = -EINTR;
2824                         break;
2825                 }
2826                 /*
2827                  * Rather than hide all in some function, I do this in
2828                  * open coded manner. You see what this really does.
2829                  * We have to guarantee mem->res.limit < mem->memsw.limit.
2830                  */
2831                 mutex_lock(&set_limit_mutex);
2832                 memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
2833                 if (memlimit > val) {
2834                         ret = -EINVAL;
2835                         mutex_unlock(&set_limit_mutex);
2836                         break;
2837                 }
2838                 memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
2839                 if (memswlimit < val)
2840                         enlarge = 1;
2841                 ret = res_counter_set_limit(&memcg->memsw, val);
2842                 if (!ret) {
2843                         if (memlimit == val)
2844                                 memcg->memsw_is_minimum = true;
2845                         else
2846                                 memcg->memsw_is_minimum = false;
2847                 }
2848                 mutex_unlock(&set_limit_mutex);
2849
2850                 if (!ret)
2851                         break;
2852
2853                 mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
2854                                                 MEM_CGROUP_RECLAIM_NOSWAP |
2855                                                 MEM_CGROUP_RECLAIM_SHRINK);
2856                 curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
2857                 /* Usage is reduced ? */
2858                 if (curusage >= oldusage)
2859                         retry_count--;
2860                 else
2861                         oldusage = curusage;
2862         }
2863         if (!ret && enlarge)
2864                 memcg_oom_recover(memcg);
2865         return ret;
2866 }
2867
2868 unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
2869                                             gfp_t gfp_mask)
2870 {
2871         unsigned long nr_reclaimed = 0;
2872         struct mem_cgroup_per_zone *mz, *next_mz = NULL;
2873         unsigned long reclaimed;
2874         int loop = 0;
2875         struct mem_cgroup_tree_per_zone *mctz;
2876         unsigned long long excess;
2877
2878         if (order > 0)
2879                 return 0;
2880
2881         mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
2882         /*
2883          * This loop can run a while, specially if mem_cgroup's continuously
2884          * keep exceeding their soft limit and putting the system under
2885          * pressure
2886          */
2887         do {
2888                 if (next_mz)
2889                         mz = next_mz;
2890                 else
2891                         mz = mem_cgroup_largest_soft_limit_node(mctz);
2892                 if (!mz)
2893                         break;
2894
2895                 reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
2896                                                 gfp_mask,
2897                                                 MEM_CGROUP_RECLAIM_SOFT);
2898                 nr_reclaimed += reclaimed;
2899                 spin_lock(&mctz->lock);
2900
2901                 /*
2902                  * If we failed to reclaim anything from this memory cgroup
2903                  * it is time to move on to the next cgroup
2904                  */
2905                 next_mz = NULL;
2906                 if (!reclaimed) {
2907                         do {
2908                                 /*
2909                                  * Loop until we find yet another one.
2910                                  *
2911                                  * By the time we get the soft_limit lock
2912                                  * again, someone might have aded the
2913                                  * group back on the RB tree. Iterate to
2914                                  * make sure we get a different mem.
2915                                  * mem_cgroup_largest_soft_limit_node returns
2916                                  * NULL if no other cgroup is present on
2917                                  * the tree
2918                                  */
2919                                 next_mz =
2920                                 __mem_cgroup_largest_soft_limit_node(mctz);
2921                                 if (next_mz == mz) {
2922                                         css_put(&next_mz->mem->css);
2923                                         next_mz = NULL;
2924                                 } else /* next_mz == NULL or other memcg */
2925                                         break;
2926                         } while (1);
2927                 }
2928                 __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
2929                 excess = res_counter_soft_limit_excess(&mz->mem->res);
2930                 /*
2931                  * One school of thought says that we should not add
2932                  * back the node to the tree if reclaim returns 0.
2933                  * But our reclaim could return 0, simply because due
2934                  * to priority we are exposing a smaller subset of
2935                  * memory to reclaim from. Consider this as a longer
2936                  * term TODO.
2937                  */
2938                 /* If excess == 0, no tree ops */
2939                 __mem_cgroup_insert_exceeded(mz->mem, mz, mctz, excess);
2940                 spin_unlock(&mctz->lock);
2941                 css_put(&mz->mem->css);
2942                 loop++;
2943                 /*
2944                  * Could not reclaim anything and there are no more
2945                  * mem cgroups to try or we seem to be looping without
2946                  * reclaiming anything.
2947                  */
2948                 if (!nr_reclaimed &&
2949                         (next_mz == NULL ||
2950                         loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
2951                         break;
2952         } while (!nr_reclaimed);
2953         if (next_mz)
2954                 css_put(&next_mz->mem->css);
2955         return nr_reclaimed;
2956 }
2957
2958 /*
2959  * This routine traverse page_cgroup in given list and drop them all.
2960  * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
2961  */
2962 static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
2963                                 int node, int zid, enum lru_list lru)
2964 {
2965         struct zone *zone;
2966         struct mem_cgroup_per_zone *mz;
2967         struct page_cgroup *pc, *busy;
2968         unsigned long flags, loop;
2969         struct list_head *list;
2970         int ret = 0;
2971
2972         zone = &NODE_DATA(node)->node_zones[zid];
2973         mz = mem_cgroup_zoneinfo(mem, node, zid);
2974         list = &mz->lists[lru];
2975
2976         loop = MEM_CGROUP_ZSTAT(mz, lru);
2977         /* give some margin against EBUSY etc...*/
2978         loop += 256;
2979         busy = NULL;
2980         while (loop--) {
2981                 ret = 0;
2982                 spin_lock_irqsave(&zone->lru_lock, flags);
2983                 if (list_empty(list)) {
2984                         spin_unlock_irqrestore(&zone->lru_lock, flags);
2985                         break;
2986                 }
2987                 pc = list_entry(list->prev, struct page_cgroup, lru);
2988                 if (busy == pc) {
2989                         list_move(&pc->lru, list);
2990                         busy = NULL;
2991                         spin_unlock_irqrestore(&zone->lru_lock, flags);
2992                         continue;
2993                 }
2994                 spin_unlock_irqrestore(&zone->lru_lock, flags);
2995
2996                 ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
2997                 if (ret == -ENOMEM)
2998                         break;
2999
3000                 if (ret == -EBUSY || ret == -EINVAL) {
3001                         /* found lock contention or "pc" is obsolete. */
3002                         busy = pc;
3003                         cond_resched();
3004                 } else
3005                         busy = NULL;
3006         }
3007
3008         if (!ret && !list_empty(list))
3009                 return -EBUSY;
3010         return ret;
3011 }
3012
3013 /*
3014  * make mem_cgroup's charge to be 0 if there is no task.
3015  * This enables deleting this mem_cgroup.
3016  */
3017 static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
3018 {
3019         int ret;
3020         int node, zid, shrink;
3021         int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
3022         struct cgroup *cgrp = mem->css.cgroup;
3023
3024         css_get(&mem->css);
3025
3026         shrink = 0;
3027         /* should free all ? */
3028         if (free_all)
3029                 goto try_to_free;
3030 move_account:
3031         do {
3032                 ret = -EBUSY;
3033                 if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
3034                         goto out;
3035                 ret = -EINTR;
3036                 if (signal_pending(current))
3037                         goto out;
3038                 /* This is for making all *used* pages to be on LRU. */
3039                 lru_add_drain_all();
3040                 drain_all_stock_sync();
3041                 ret = 0;
3042                 for_each_node_state(node, N_HIGH_MEMORY) {
3043                         for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
3044                                 enum lru_list l;
3045                                 for_each_lru(l) {
3046                                         ret = mem_cgroup_force_empty_list(mem,
3047                                                         node, zid, l);
3048                                         if (ret)
3049                                                 break;
3050                                 }
3051                         }
3052                         if (ret)
3053                                 break;
3054                 }
3055                 memcg_oom_recover(mem);
3056                 /* it seems parent cgroup doesn't have enough mem */
3057                 if (ret == -ENOMEM)
3058                         goto try_to_free;
3059                 cond_resched();
3060         /* "ret" should also be checked to ensure all lists are empty. */
3061         } while (mem->res.usage > 0 || ret);
3062 out:
3063         css_put(&mem->css);
3064         return ret;
3065
3066 try_to_free:
3067         /* returns EBUSY if there is a task or if we come here twice. */
3068         if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
3069                 ret = -EBUSY;
3070                 goto out;
3071         }
3072         /* we call try-to-free pages for make this cgroup empty */
3073         lru_add_drain_all();
3074         /* try to free all pages in this cgroup */
3075         shrink = 1;
3076         while (nr_retries && mem->res.usage > 0) {
3077                 int progress;
3078
3079                 if (signal_pending(current)) {
3080                         ret = -EINTR;
3081                         goto out;
3082                 }
3083                 progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
3084                                                 false, get_swappiness(mem));
3085                 if (!progress) {
3086                         nr_retries--;
3087                         /* maybe some writeback is necessary */
3088                         congestion_wait(BLK_RW_ASYNC, HZ/10);
3089                 }
3090
3091         }
3092         lru_add_drain();
3093         /* try move_account...there may be some *locked* pages. */
3094         goto move_account;
3095 }
3096
3097 int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
3098 {
3099         return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
3100 }
3101
3102
3103 static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
3104 {
3105         return mem_cgroup_from_cont(cont)->use_hierarchy;
3106 }
3107
3108 static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
3109                                         u64 val)
3110 {
3111         int retval = 0;
3112         struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3113         struct cgroup *parent = cont->parent;
3114         struct mem_cgroup *parent_mem = NULL;
3115
3116         if (parent)
3117                 parent_mem = mem_cgroup_from_cont(parent);
3118
3119         cgroup_lock();
3120         /*
3121          * If parent's use_hierarchy is set, we can't make any modifications
3122          * in the child subtrees. If it is unset, then the change can
3123          * occur, provided the current cgroup has no children.
3124          *
3125          * For the root cgroup, parent_mem is NULL, we allow value to be
3126          * set if there are no children.
3127          */
3128         if ((!parent_mem || !parent_mem->use_hierarchy) &&
3129                                 (val == 1 || val == 0)) {
3130                 if (list_empty(&cont->children))
3131                         mem->use_hierarchy = val;
3132                 else
3133                         retval = -EBUSY;
3134         } else
3135                 retval = -EINVAL;
3136         cgroup_unlock();
3137
3138         return retval;
3139 }
3140
3141 struct mem_cgroup_idx_data {
3142         s64 val;
3143         enum mem_cgroup_stat_index idx;
3144 };
3145
3146 static int
3147 mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data)
3148 {
3149         struct mem_cgroup_idx_data *d = data;
3150         d->val += mem_cgroup_read_stat(mem, d->idx);
3151         return 0;
3152 }
3153
3154 static void
3155 mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
3156                                 enum mem_cgroup_stat_index idx, s64 *val)
3157 {
3158         struct mem_cgroup_idx_data d;
3159         d.idx = idx;
3160         d.val = 0;
3161         mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat);
3162         *val = d.val;
3163 }
3164
3165 static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
3166 {
3167         u64 idx_val, val;
3168
3169         if (!mem_cgroup_is_root(mem)) {
3170                 if (!swap)
3171                         return res_counter_read_u64(&mem->res, RES_USAGE);
3172                 else
3173                         return res_counter_read_u64(&mem->memsw, RES_USAGE);
3174         }
3175
3176         mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE, &idx_val);
3177         val = idx_val;
3178         mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS, &idx_val);
3179         val += idx_val;
3180
3181         if (swap) {
3182                 mem_cgroup_get_recursive_idx_stat(mem,
3183                                 MEM_CGROUP_STAT_SWAPOUT, &idx_val);
3184                 val += idx_val;
3185         }
3186
3187         return val << PAGE_SHIFT;
3188 }
3189
3190 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
3191 {
3192         struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3193         u64 val;
3194         int type, name;
3195
3196         type = MEMFILE_TYPE(cft->private);
3197         name = MEMFILE_ATTR(cft->private);
3198         switch (type) {
3199         case _MEM:
3200                 if (name == RES_USAGE)
3201                         val = mem_cgroup_usage(mem, false);
3202                 else
3203                         val = res_counter_read_u64(&mem->res, name);
3204                 break;
3205         case _MEMSWAP:
3206                 if (name == RES_USAGE)
3207                         val = mem_cgroup_usage(mem, true);
3208                 else
3209                         val = res_counter_read_u64(&mem->memsw, name);
3210                 break;
3211         default:
3212                 BUG();
3213                 break;
3214         }
3215         return val;
3216 }
3217 /*
3218  * The user of this function is...
3219  * RES_LIMIT.
3220  */
3221 static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
3222                             const char *buffer)
3223 {
3224         struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3225         int type, name;
3226         unsigned long long val;
3227         int ret;
3228
3229         type = MEMFILE_TYPE(cft->private);
3230         name = MEMFILE_ATTR(cft->private);
3231         switch (name) {
3232         case RES_LIMIT:
3233                 if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3234                         ret = -EINVAL;
3235                         break;
3236                 }
3237                 /* This function does all necessary parse...reuse it */
3238                 ret = res_counter_memparse_write_strategy(buffer, &val);
3239                 if (ret)
3240                         break;
3241                 if (type == _MEM)
3242                         ret = mem_cgroup_resize_limit(memcg, val);
3243                 else
3244                         ret = mem_cgroup_resize_memsw_limit(memcg, val);
3245                 break;
3246         case RES_SOFT_LIMIT:
3247                 ret = res_counter_memparse_write_strategy(buffer, &val);
3248                 if (ret)
3249                         break;
3250                 /*
3251                  * For memsw, soft limits are hard to implement in terms
3252                  * of semantics, for now, we support soft limits for
3253                  * control without swap
3254                  */
3255                 if (type == _MEM)
3256                         ret = res_counter_set_soft_limit(&memcg->res, val);
3257                 else
3258                         ret = -EINVAL;
3259                 break;
3260         default:
3261                 ret = -EINVAL; /* should be BUG() ? */
3262                 break;
3263         }
3264         return ret;
3265 }
3266
3267 static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
3268                 unsigned long long *mem_limit, unsigned long long *memsw_limit)
3269 {
3270         struct cgroup *cgroup;
3271         unsigned long long min_limit, min_memsw_limit, tmp;
3272
3273         min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3274         min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3275         cgroup = memcg->css.cgroup;
3276         if (!memcg->use_hierarchy)
3277                 goto out;
3278
3279         while (cgroup->parent) {
3280                 cgroup = cgroup->parent;
3281                 memcg = mem_cgroup_from_cont(cgroup);
3282                 if (!memcg->use_hierarchy)
3283                         break;
3284                 tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
3285                 min_limit = min(min_limit, tmp);
3286                 tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3287                 min_memsw_limit = min(min_memsw_limit, tmp);
3288         }
3289 out:
3290         *mem_limit = min_limit;
3291         *memsw_limit = min_memsw_limit;
3292         return;
3293 }
3294
3295 static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
3296 {
3297         struct mem_cgroup *mem;
3298         int type, name;
3299
3300         mem = mem_cgroup_from_cont(cont);
3301         type = MEMFILE_TYPE(event);
3302         name = MEMFILE_ATTR(event);
3303         switch (name) {
3304         case RES_MAX_USAGE:
3305                 if (type == _MEM)
3306                         res_counter_reset_max(&mem->res);
3307                 else
3308                         res_counter_reset_max(&mem->memsw);
3309                 break;
3310         case RES_FAILCNT:
3311                 if (type == _MEM)
3312                         res_counter_reset_failcnt(&mem->res);
3313                 else
3314                         res_counter_reset_failcnt(&mem->memsw);
3315                 break;
3316         }
3317
3318         return 0;
3319 }
3320
3321 static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
3322                                         struct cftype *cft)
3323 {
3324         return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
3325 }
3326
3327 #ifdef CONFIG_MMU
3328 static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3329                                         struct cftype *cft, u64 val)
3330 {
3331         struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3332
3333         if (val >= (1 << NR_MOVE_TYPE))
3334                 return -EINVAL;
3335         /*
3336          * We check this value several times in both in can_attach() and
3337          * attach(), so we need cgroup lock to prevent this value from being
3338          * inconsistent.
3339          */
3340         cgroup_lock();
3341         mem->move_charge_at_immigrate = val;
3342         cgroup_unlock();
3343
3344         return 0;
3345 }
3346 #else
3347 static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3348                                         struct cftype *cft, u64 val)
3349 {
3350         return -ENOSYS;
3351 }
3352 #endif
3353
3354
3355 /* For read statistics */
3356 enum {
3357         MCS_CACHE,
3358         MCS_RSS,
3359         MCS_FILE_MAPPED,
3360         MCS_PGPGIN,
3361         MCS_PGPGOUT,
3362         MCS_SWAP,
3363         MCS_INACTIVE_ANON,
3364         MCS_ACTIVE_ANON,
3365         MCS_INACTIVE_FILE,
3366         MCS_ACTIVE_FILE,
3367         MCS_UNEVICTABLE,
3368         NR_MCS_STAT,
3369 };
3370
3371 struct mcs_total_stat {
3372         s64 stat[NR_MCS_STAT];
3373 };
3374
3375 struct {
3376         char *local_name;
3377         char *total_name;
3378 } memcg_stat_strings[NR_MCS_STAT] = {
3379         {"cache", "total_cache"},
3380         {"rss", "total_rss"},
3381         {"mapped_file", "total_mapped_file"},
3382         {"pgpgin", "total_pgpgin"},
3383         {"pgpgout", "total_pgpgout"},
3384         {"swap", "total_swap"},
3385         {"inactive_anon", "total_inactive_anon"},
3386         {"active_anon", "total_active_anon"},
3387         {"inactive_file", "total_inactive_file"},
3388         {"active_file", "total_active_file"},
3389         {"unevictable", "total_unevictable"}
3390 };
3391
3392
3393 static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
3394 {
3395         struct mcs_total_stat *s = data;
3396         s64 val;
3397
3398         /* per cpu stat */
3399         val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
3400         s->stat[MCS_CACHE] += val * PAGE_SIZE;
3401         val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
3402         s->stat[MCS_RSS] += val * PAGE_SIZE;
3403         val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_MAPPED);
3404         s->stat[MCS_FILE_MAPPED] += val * PAGE_SIZE;
3405         val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGIN_COUNT);
3406         s->stat[MCS_PGPGIN] += val;
3407         val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGOUT_COUNT);
3408         s->stat[MCS_PGPGOUT] += val;
3409         if (do_swap_account) {
3410                 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
3411                 s->stat[MCS_SWAP] += val * PAGE_SIZE;
3412         }
3413
3414         /* per zone stat */
3415         val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
3416         s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
3417         val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_ANON);
3418         s->stat[MCS_ACTIVE_ANON] += val * PAGE_SIZE;
3419         val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_FILE);
3420         s->stat[MCS_INACTIVE_FILE] += val * PAGE_SIZE;
3421         val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_FILE);
3422         s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE;
3423         val = mem_cgroup_get_local_zonestat(mem, LRU_UNEVICTABLE);
3424         s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE;
3425         return 0;
3426 }
3427
3428 static void
3429 mem_cgroup_get_total_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
3430 {
3431         mem_cgroup_walk_tree(mem, s, mem_cgroup_get_local_stat);
3432 }
3433
3434 static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
3435                                  struct cgroup_map_cb *cb)
3436 {
3437         struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
3438         struct mcs_total_stat mystat;
3439         int i;
3440
3441         memset(&mystat, 0, sizeof(mystat));
3442         mem_cgroup_get_local_stat(mem_cont, &mystat);
3443
3444         for (i = 0; i < NR_MCS_STAT; i++) {
3445                 if (i == MCS_SWAP && !do_swap_account)
3446                         continue;
3447                 cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]);
3448         }
3449
3450         /* Hierarchical information */
3451         {
3452                 unsigned long long limit, memsw_limit;
3453                 memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
3454                 cb->fill(cb, "hierarchical_memory_limit", limit);
3455                 if (do_swap_account)
3456                         cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
3457         }
3458
3459         memset(&mystat, 0, sizeof(mystat));
3460         mem_cgroup_get_total_stat(mem_cont, &mystat);
3461         for (i = 0; i < NR_MCS_STAT; i++) {
3462                 if (i == MCS_SWAP && !do_swap_account)
3463                         continue;
3464                 cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]);
3465         }
3466
3467 #ifdef CONFIG_DEBUG_VM
3468         cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
3469
3470         {
3471                 int nid, zid;
3472                 struct mem_cgroup_per_zone *mz;
3473                 unsigned long recent_rotated[2] = {0, 0};
3474                 unsigned long recent_scanned[2] = {0, 0};
3475
3476                 for_each_online_node(nid)
3477                         for (zid = 0; zid < MAX_NR_ZONES; zid++) {
3478                                 mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
3479
3480                                 recent_rotated[0] +=
3481                                         mz->reclaim_stat.recent_rotated[0];
3482                                 recent_rotated[1] +=
3483                                         mz->reclaim_stat.recent_rotated[1];
3484                                 recent_scanned[0] +=
3485                                         mz->reclaim_stat.recent_scanned[0];
3486                                 recent_scanned[1] +=
3487                                         mz->reclaim_stat.recent_scanned[1];
3488                         }
3489                 cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
3490                 cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
3491                 cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
3492                 cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
3493         }
3494 #endif
3495
3496         return 0;
3497 }
3498
3499 static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
3500 {
3501         struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3502
3503         return get_swappiness(memcg);
3504 }
3505
3506 static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
3507                                        u64 val)
3508 {
3509         struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3510         struct mem_cgroup *parent;
3511
3512         if (val > 100)
3513                 return -EINVAL;
3514
3515         if (cgrp->parent == NULL)
3516                 return -EINVAL;
3517
3518         parent = mem_cgroup_from_cont(cgrp->parent);
3519
3520         cgroup_lock();
3521
3522         /* If under hierarchy, only empty-root can set this value */
3523         if ((parent->use_hierarchy) ||
3524             (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
3525                 cgroup_unlock();
3526                 return -EINVAL;
3527         }
3528
3529         spin_lock(&memcg->reclaim_param_lock);
3530         memcg->swappiness = val;
3531         spin_unlock(&memcg->reclaim_param_lock);
3532
3533         cgroup_unlock();
3534
3535         return 0;
3536 }
3537
3538 static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
3539 {
3540         struct mem_cgroup_threshold_ary *t;
3541         u64 usage;
3542         int i;
3543
3544         rcu_read_lock();
3545         if (!swap)
3546                 t = rcu_dereference(memcg->thresholds.primary);
3547         else
3548                 t = rcu_dereference(memcg->memsw_thresholds.primary);
3549
3550         if (!t)
3551                 goto unlock;
3552
3553         usage = mem_cgroup_usage(memcg, swap);
3554
3555         /*
3556          * current_threshold points to threshold just below usage.
3557          * If it's not true, a threshold was crossed after last
3558          * call of __mem_cgroup_threshold().
3559          */
3560         i = t->current_threshold;
3561
3562         /*
3563          * Iterate backward over array of thresholds starting from
3564          * current_threshold and check if a threshold is crossed.
3565          * If none of thresholds below usage is crossed, we read
3566          * only one element of the array here.
3567          */
3568         for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
3569                 eventfd_signal(t->entries[i].eventfd, 1);
3570
3571         /* i = current_threshold + 1 */
3572         i++;
3573
3574         /*
3575          * Iterate forward over array of thresholds starting from
3576          * current_threshold+1 and check if a threshold is crossed.
3577          * If none of thresholds above usage is crossed, we read
3578          * only one element of the array here.
3579          */
3580         for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
3581                 eventfd_signal(t->entries[i].eventfd, 1);
3582
3583         /* Update current_threshold */
3584         t->current_threshold = i - 1;
3585 unlock:
3586         rcu_read_unlock();
3587 }
3588
3589 static void mem_cgroup_threshold(struct mem_cgroup *memcg)
3590 {
3591         while (memcg) {
3592                 __mem_cgroup_threshold(memcg, false);
3593                 if (do_swap_account)
3594                         __mem_cgroup_threshold(memcg, true);
3595
3596                 memcg = parent_mem_cgroup(memcg);
3597         }
3598 }
3599
3600 static int compare_thresholds(const void *a, const void *b)
3601 {
3602         const struct mem_cgroup_threshold *_a = a;
3603         const struct mem_cgroup_threshold *_b = b;
3604
3605         return _a->threshold - _b->threshold;
3606 }
3607
3608 static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem, void *data)
3609 {
3610         struct mem_cgroup_eventfd_list *ev;
3611
3612         list_for_each_entry(ev, &mem->oom_notify, list)
3613                 eventfd_signal(ev->eventfd, 1);
3614         return 0;
3615 }
3616
3617 static void mem_cgroup_oom_notify(struct mem_cgroup *mem)
3618 {
3619         mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_notify_cb);
3620 }
3621
3622 static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
3623         struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
3624 {
3625         struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3626         struct mem_cgroup_thresholds *thresholds;
3627         struct mem_cgroup_threshold_ary *new;
3628         int type = MEMFILE_TYPE(cft->private);
3629         u64 threshold, usage;
3630         int i, size, ret;
3631
3632         ret = res_counter_memparse_write_strategy(args, &threshold);
3633         if (ret)
3634                 return ret;
3635
3636         mutex_lock(&memcg->thresholds_lock);
3637
3638         if (type == _MEM)
3639                 thresholds = &memcg->thresholds;
3640         else if (type == _MEMSWAP)
3641                 thresholds = &memcg->memsw_thresholds;
3642         else
3643                 BUG();
3644
3645         usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3646
3647         /* Check if a threshold crossed before adding a new one */
3648         if (thresholds->primary)
3649                 __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3650
3651         size = thresholds->primary ? thresholds->primary->size + 1 : 1;
3652
3653         /* Allocate memory for new array of thresholds */
3654         new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
3655                         GFP_KERNEL);
3656         if (!new) {
3657                 ret = -ENOMEM;
3658                 goto unlock;
3659         }
3660         new->size = size;
3661
3662         /* Copy thresholds (if any) to new array */
3663         if (thresholds->primary) {
3664                 memcpy(new->entries, thresholds->primary->entries, (size - 1) *
3665                                 sizeof(struct mem_cgroup_threshold));
3666         }
3667
3668         /* Add new threshold */
3669         new->entries[size - 1].eventfd = eventfd;
3670         new->entries[size - 1].threshold = threshold;
3671
3672         /* Sort thresholds. Registering of new threshold isn't time-critical */
3673         sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
3674                         compare_thresholds, NULL);
3675
3676         /* Find current threshold */
3677         new->current_threshold = -1;
3678         for (i = 0; i < size; i++) {
3679                 if (new->entries[i].threshold < usage) {
3680                         /*
3681                          * new->current_threshold will not be used until
3682                          * rcu_assign_pointer(), so it's safe to increment
3683                          * it here.
3684                          */
3685                         ++new->current_threshold;
3686                 }
3687         }
3688
3689         /* Free old spare buffer and save old primary buffer as spare */
3690         kfree(thresholds->spare);
3691         thresholds->spare = thresholds->primary;
3692
3693         rcu_assign_pointer(thresholds->primary, new);
3694
3695         /* To be sure that nobody uses thresholds */
3696         synchronize_rcu();
3697
3698 unlock:
3699         mutex_unlock(&memcg->thresholds_lock);
3700
3701         return ret;
3702 }
3703
3704 static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
3705         struct cftype *cft, struct eventfd_ctx *eventfd)
3706 {
3707         struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3708         struct mem_cgroup_thresholds *thresholds;
3709         struct mem_cgroup_threshold_ary *new;
3710         int type = MEMFILE_TYPE(cft->private);
3711         u64 usage;
3712         int i, j, size;
3713
3714         mutex_lock(&memcg->thresholds_lock);
3715         if (type == _MEM)
3716                 thresholds = &memcg->thresholds;
3717         else if (type == _MEMSWAP)
3718                 thresholds = &memcg->memsw_thresholds;
3719         else
3720                 BUG();
3721
3722         /*
3723          * Something went wrong if we trying to unregister a threshold
3724          * if we don't have thresholds
3725          */
3726         BUG_ON(!thresholds);
3727
3728         usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3729
3730         /* Check if a threshold crossed before removing */
3731         __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3732
3733         /* Calculate new number of threshold */
3734         size = 0;
3735         for (i = 0; i < thresholds->primary->size; i++) {
3736                 if (thresholds->primary->entries[i].eventfd != eventfd)
3737                         size++;
3738         }
3739
3740         new = thresholds->spare;
3741
3742         /* Set thresholds array to NULL if we don't have thresholds */
3743         if (!size) {
3744                 kfree(new);
3745                 new = NULL;
3746                 goto swap_buffers;
3747         }
3748
3749         new->size = size;
3750
3751         /* Copy thresholds and find current threshold */
3752         new->current_threshold = -1;
3753         for (i = 0, j = 0; i < thresholds->primary->size; i++) {
3754                 if (thresholds->primary->entries[i].eventfd == eventfd)
3755                         continue;
3756
3757                 new->entries[j] = thresholds->primary->entries[i];
3758                 if (new->entries[j].threshold < usage) {
3759                         /*
3760                          * new->current_threshold will not be used
3761                          * until rcu_assign_pointer(), so it's safe to increment
3762                          * it here.
3763                          */
3764                         ++new->current_threshold;
3765                 }
3766                 j++;
3767         }
3768
3769 swap_buffers:
3770         /* Swap primary and spare array */
3771         thresholds->spare = thresholds->primary;
3772         rcu_assign_pointer(thresholds->primary, new);
3773
3774         /* To be sure that nobody uses thresholds */
3775         synchronize_rcu();
3776
3777         mutex_unlock(&memcg->thresholds_lock);
3778 }
3779
3780 static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
3781         struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
3782 {
3783         struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3784         struct mem_cgroup_eventfd_list *event;
3785         int type = MEMFILE_TYPE(cft->private);
3786
3787         BUG_ON(type != _OOM_TYPE);
3788         event = kmalloc(sizeof(*event), GFP_KERNEL);
3789         if (!event)
3790                 return -ENOMEM;
3791
3792         mutex_lock(&memcg_oom_mutex);
3793
3794         event->eventfd = eventfd;
3795         list_add(&event->list, &memcg->oom_notify);
3796
3797         /* already in OOM ? */
3798         if (atomic_read(&memcg->oom_lock))
3799                 eventfd_signal(eventfd, 1);
3800         mutex_unlock(&memcg_oom_mutex);
3801
3802         return 0;
3803 }
3804
3805 static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
3806         struct cftype *cft, struct eventfd_ctx *eventfd)
3807 {
3808         struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3809         struct mem_cgroup_eventfd_list *ev, *tmp;
3810         int type = MEMFILE_TYPE(cft->private);
3811
3812         BUG_ON(type != _OOM_TYPE);
3813
3814         mutex_lock(&memcg_oom_mutex);
3815
3816         list_for_each_entry_safe(ev, tmp, &mem->oom_notify, list) {
3817                 if (ev->eventfd == eventfd) {
3818                         list_del(&ev->list);
3819                         kfree(ev);
3820                 }
3821         }
3822
3823         mutex_unlock(&memcg_oom_mutex);
3824 }
3825
3826 static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
3827         struct cftype *cft,  struct cgroup_map_cb *cb)
3828 {
3829         struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3830
3831         cb->fill(cb, "oom_kill_disable", mem->oom_kill_disable);
3832
3833         if (atomic_read(&mem->oom_lock))
3834                 cb->fill(cb, "under_oom", 1);
3835         else
3836                 cb->fill(cb, "under_oom", 0);
3837         return 0;
3838 }
3839
3840 static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
3841         struct cftype *cft, u64 val)
3842 {
3843         struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3844         struct mem_cgroup *parent;
3845
3846         /* cannot set to root cgroup and only 0 and 1 are allowed */
3847         if (!cgrp->parent || !((val == 0) || (val == 1)))
3848                 return -EINVAL;
3849
3850         parent = mem_cgroup_from_cont(cgrp->parent);
3851
3852         cgroup_lock();
3853         /* oom-kill-disable is a flag for subhierarchy. */
3854         if ((parent->use_hierarchy) ||
3855             (mem->use_hierarchy && !list_empty(&cgrp->children))) {
3856                 cgroup_unlock();
3857                 return -EINVAL;
3858         }
3859         mem->oom_kill_disable = val;
3860         if (!val)
3861                 memcg_oom_recover(mem);
3862         cgroup_unlock();
3863         return 0;
3864 }
3865
3866 static struct cftype mem_cgroup_files[] = {
3867         {
3868                 .name = "usage_in_bytes",
3869                 .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
3870                 .read_u64 = mem_cgroup_read,
3871                 .register_event = mem_cgroup_usage_register_event,
3872                 .unregister_event = mem_cgroup_usage_unregister_event,
3873         },
3874         {
3875                 .name = "max_usage_in_bytes",
3876                 .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
3877                 .trigger = mem_cgroup_reset,
3878                 .read_u64 = mem_cgroup_read,
3879         },
3880         {
3881                 .name = "limit_in_bytes",
3882                 .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
3883                 .write_string = mem_cgroup_write,
3884                 .read_u64 = mem_cgroup_read,
3885         },
3886         {
3887                 .name = "soft_limit_in_bytes",
3888                 .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
3889                 .write_string = mem_cgroup_write,
3890                 .read_u64 = mem_cgroup_read,
3891         },
3892         {
3893                 .name = "failcnt",
3894                 .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
3895                 .trigger = mem_cgroup_reset,
3896                 .read_u64 = mem_cgroup_read,
3897         },
3898         {
3899                 .name = "stat",
3900                 .read_map = mem_control_stat_show,
3901         },
3902         {
3903                 .name = "force_empty",
3904                 .trigger = mem_cgroup_force_empty_write,
3905         },
3906         {
3907                 .name = "use_hierarchy",
3908                 .write_u64 = mem_cgroup_hierarchy_write,
3909                 .read_u64 = mem_cgroup_hierarchy_read,
3910         },
3911         {
3912                 .name = "swappiness",
3913                 .read_u64 = mem_cgroup_swappiness_read,
3914                 .write_u64 = mem_cgroup_swappiness_write,
3915         },
3916         {
3917                 .name = "move_charge_at_immigrate",
3918                 .read_u64 = mem_cgroup_move_charge_read,
3919                 .write_u64 = mem_cgroup_move_charge_write,
3920         },
3921         {
3922                 .name = "oom_control",
3923                 .read_map = mem_cgroup_oom_control_read,
3924                 .write_u64 = mem_cgroup_oom_control_write,
3925                 .register_event = mem_cgroup_oom_register_event,
3926                 .unregister_event = mem_cgroup_oom_unregister_event,
3927                 .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
3928         },
3929 };
3930
3931 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
3932 static struct cftype memsw_cgroup_files[] = {
3933         {
3934                 .name = "memsw.usage_in_bytes",
3935                 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
3936                 .read_u64 = mem_cgroup_read,
3937                 .register_event = mem_cgroup_usage_register_event,
3938                 .unregister_event = mem_cgroup_usage_unregister_event,
3939         },
3940         {
3941                 .name = "memsw.max_usage_in_bytes",
3942                 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
3943                 .trigger = mem_cgroup_reset,
3944                 .read_u64 = mem_cgroup_read,
3945         },
3946         {
3947                 .name = "memsw.limit_in_bytes",
3948                 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
3949                 .write_string = mem_cgroup_write,
3950                 .read_u64 = mem_cgroup_read,
3951         },
3952         {
3953                 .name = "memsw.failcnt",
3954                 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
3955                 .trigger = mem_cgroup_reset,
3956                 .read_u64 = mem_cgroup_read,
3957         },
3958 };
3959
3960 static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
3961 {
3962         if (!do_swap_account)
3963                 return 0;
3964         return cgroup_add_files(cont, ss, memsw_cgroup_files,
3965                                 ARRAY_SIZE(memsw_cgroup_files));
3966 };
3967 #else
3968 static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
3969 {
3970         return 0;
3971 }
3972 #endif
3973
3974 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
3975 {
3976         struct mem_cgroup_per_node *pn;
3977         struct mem_cgroup_per_zone *mz;
3978         enum lru_list l;
3979         int zone, tmp = node;
3980         /*
3981          * This routine is called against possible nodes.
3982          * But it's BUG to call kmalloc() against offline node.
3983          *
3984          * TODO: this routine can waste much memory for nodes which will
3985          *       never be onlined. It's better to use memory hotplug callback
3986          *       function.
3987          */
3988         if (!node_state(node, N_NORMAL_MEMORY))
3989                 tmp = -1;
3990         pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
3991         if (!pn)
3992                 return 1;
3993
3994         mem->info.nodeinfo[node] = pn;
3995         memset(pn, 0, sizeof(*pn));
3996
3997         for (zone = 0; zone < MAX_NR_ZONES; zone++) {
3998                 mz = &pn->zoneinfo[zone];
3999                 for_each_lru(l)
4000                         INIT_LIST_HEAD(&mz->lists[l]);
4001                 mz->usage_in_excess = 0;
4002                 mz->on_tree = false;
4003                 mz->mem = mem;
4004         }
4005         return 0;
4006 }
4007
4008 static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
4009 {
4010         kfree(mem->info.nodeinfo[node]);
4011 }
4012
4013 static struct mem_cgroup *mem_cgroup_alloc(void)
4014 {
4015         struct mem_cgroup *mem;
4016         int size = sizeof(struct mem_cgroup);
4017
4018         /* Can be very big if MAX_NUMNODES is very big */
4019         if (size < PAGE_SIZE)
4020                 mem = kmalloc(size, GFP_KERNEL);
4021         else
4022                 mem = vmalloc(size);
4023
4024         if (!mem)
4025                 return NULL;
4026
4027         memset(mem, 0, size);
4028         mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
4029         if (!mem->stat) {
4030                 if (size < PAGE_SIZE)
4031                         kfree(mem);
4032                 else
4033                         vfree(mem);
4034                 mem = NULL;
4035         }
4036         return mem;
4037 }
4038
4039 /*
4040  * At destroying mem_cgroup, references from swap_cgroup can remain.
4041  * (scanning all at force_empty is too costly...)
4042  *
4043  * Instead of clearing all references at force_empty, we remember
4044  * the number of reference from swap_cgroup and free mem_cgroup when
4045  * it goes down to 0.
4046  *
4047  * Removal of cgroup itself succeeds regardless of refs from swap.
4048  */
4049
4050 static void __mem_cgroup_free(struct mem_cgroup *mem)
4051 {
4052         int node;
4053
4054         mem_cgroup_remove_from_trees(mem);
4055         free_css_id(&mem_cgroup_subsys, &mem->css);
4056
4057         for_each_node_state(node, N_POSSIBLE)
4058                 free_mem_cgroup_per_zone_info(mem, node);
4059
4060         free_percpu(mem->stat);
4061         if (sizeof(struct mem_cgroup) < PAGE_SIZE)
4062                 kfree(mem);
4063         else
4064                 vfree(mem);
4065 }
4066
4067 static void mem_cgroup_get(struct mem_cgroup *mem)
4068 {
4069         atomic_inc(&mem->refcnt);
4070 }
4071
4072 static void __mem_cgroup_put(struct mem_cgroup *mem, int count)
4073 {
4074         if (atomic_sub_and_test(count, &mem->refcnt)) {
4075                 struct mem_cgroup *parent = parent_mem_cgroup(mem);
4076                 __mem_cgroup_free(mem);
4077                 if (parent)
4078                         mem_cgroup_put(parent);
4079         }
4080 }
4081
4082 static void mem_cgroup_put(struct mem_cgroup *mem)
4083 {
4084         __mem_cgroup_put(mem, 1);
4085 }
4086
4087 /*
4088  * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
4089  */
4090 static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem)
4091 {
4092         if (!mem->res.parent)
4093                 return NULL;
4094         return mem_cgroup_from_res_counter(mem->res.parent, res);
4095 }
4096
4097 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4098 static void __init enable_swap_cgroup(void)
4099 {
4100         if (!mem_cgroup_disabled() && really_do_swap_account)
4101                 do_swap_account = 1;
4102 }
4103 #else
4104 static void __init enable_swap_cgroup(void)
4105 {
4106 }
4107 #endif
4108
4109 static int mem_cgroup_soft_limit_tree_init(void)
4110 {
4111         struct mem_cgroup_tree_per_node *rtpn;
4112         struct mem_cgroup_tree_per_zone *rtpz;
4113         int tmp, node, zone;
4114
4115         for_each_node_state(node, N_POSSIBLE) {
4116                 tmp = node;
4117                 if (!node_state(node, N_NORMAL_MEMORY))
4118                         tmp = -1;
4119                 rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
4120                 if (!rtpn)
4121                         return 1;
4122
4123                 soft_limit_tree.rb_tree_per_node[node] = rtpn;
4124
4125                 for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4126                         rtpz = &rtpn->rb_tree_per_zone[zone];
4127                         rtpz->rb_root = RB_ROOT;
4128                         spin_lock_init(&rtpz->lock);
4129                 }
4130         }
4131         return 0;
4132 }
4133
4134 static struct cgroup_subsys_state * __ref
4135 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
4136 {
4137         struct mem_cgroup *mem, *parent;
4138         long error = -ENOMEM;
4139         int node;
4140
4141         mem = mem_cgroup_alloc();
4142         if (!mem)
4143                 return ERR_PTR(error);
4144
4145         for_each_node_state(node, N_POSSIBLE)
4146                 if (alloc_mem_cgroup_per_zone_info(mem, node))
4147                         goto free_out;
4148
4149         /* root ? */
4150         if (cont->parent == NULL) {
4151                 int cpu;
4152                 enable_swap_cgroup();
4153                 parent = NULL;
4154                 root_mem_cgroup = mem;
4155                 if (mem_cgroup_soft_limit_tree_init())
4156                         goto free_out;
4157                 for_each_possible_cpu(cpu) {
4158                         struct memcg_stock_pcp *stock =
4159                                                 &per_cpu(memcg_stock, cpu);
4160                         INIT_WORK(&stock->work, drain_local_stock);
4161                 }
4162                 hotcpu_notifier(memcg_stock_cpu_callback, 0);
4163         } else {
4164                 parent = mem_cgroup_from_cont(cont->parent);
4165                 mem->use_hierarchy = parent->use_hierarchy;
4166                 mem->oom_kill_disable = parent->oom_kill_disable;
4167         }
4168
4169         if (parent && parent->use_hierarchy) {
4170                 res_counter_init(&mem->res, &parent->res);
4171                 res_counter_init(&mem->memsw, &parent->memsw);
4172                 /*
4173                  * We increment refcnt of the parent to ensure that we can
4174                  * safely access it on res_counter_charge/uncharge.
4175                  * This refcnt will be decremented when freeing this
4176                  * mem_cgroup(see mem_cgroup_put).
4177                  */
4178                 mem_cgroup_get(parent);
4179         } else {
4180                 res_counter_init(&mem->res, NULL);
4181                 res_counter_init(&mem->memsw, NULL);
4182         }
4183         mem->last_scanned_child = 0;
4184         spin_lock_init(&mem->reclaim_param_lock);
4185         INIT_LIST_HEAD(&mem->oom_notify);
4186
4187         if (parent)
4188                 mem->swappiness = get_swappiness(parent);
4189         atomic_set(&mem->refcnt, 1);
4190         mem->move_charge_at_immigrate = 0;
4191         mutex_init(&mem->thresholds_lock);
4192         return &mem->css;
4193 free_out:
4194         __mem_cgroup_free(mem);
4195         root_mem_cgroup = NULL;
4196         return ERR_PTR(error);
4197 }
4198
4199 static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
4200                                         struct cgroup *cont)
4201 {
4202         struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
4203
4204         return mem_cgroup_force_empty(mem, false);
4205 }
4206
4207 static void mem_cgroup_destroy(struct cgroup_subsys *ss,
4208                                 struct cgroup *cont)
4209 {
4210         struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
4211
4212         mem_cgroup_put(mem);
4213 }
4214
4215 static int mem_cgroup_populate(struct cgroup_subsys *ss,
4216                                 struct cgroup *cont)
4217 {
4218         int ret;
4219
4220         ret = cgroup_add_files(cont, ss, mem_cgroup_files,
4221                                 ARRAY_SIZE(mem_cgroup_files));
4222
4223         if (!ret)
4224                 ret = register_memsw_files(cont, ss);
4225         return ret;
4226 }
4227
4228 #ifdef CONFIG_MMU
4229 /* Handlers for move charge at task migration. */
4230 #define PRECHARGE_COUNT_AT_ONCE 256
4231 static int mem_cgroup_do_precharge(unsigned long count)
4232 {
4233         int ret = 0;
4234         int batch_count = PRECHARGE_COUNT_AT_ONCE;
4235         struct mem_cgroup *mem = mc.to;
4236
4237         if (mem_cgroup_is_root(mem)) {
4238                 mc.precharge += count;
4239                 /* we don't need css_get for root */
4240                 return ret;
4241         }
4242         /* try to charge at once */
4243         if (count > 1) {
4244                 struct res_counter *dummy;
4245                 /*
4246                  * "mem" cannot be under rmdir() because we've already checked
4247                  * by cgroup_lock_live_cgroup() that it is not removed and we
4248                  * are still under the same cgroup_mutex. So we can postpone
4249                  * css_get().
4250                  */
4251                 if (res_counter_charge(&mem->res, PAGE_SIZE * count, &dummy))
4252                         goto one_by_one;
4253                 if (do_swap_account && res_counter_charge(&mem->memsw,
4254                                                 PAGE_SIZE * count, &dummy)) {
4255                         res_counter_uncharge(&mem->res, PAGE_SIZE * count);
4256                         goto one_by_one;
4257                 }
4258                 mc.precharge += count;
4259                 return ret;
4260         }
4261 one_by_one:
4262         /* fall back to one by one charge */
4263         while (count--) {
4264                 if (signal_pending(current)) {
4265                         ret = -EINTR;
4266                         break;
4267                 }
4268                 if (!batch_count--) {
4269                         batch_count = PRECHARGE_COUNT_AT_ONCE;
4270                         cond_resched();
4271                 }
4272                 ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
4273                 if (ret || !mem)
4274                         /* mem_cgroup_clear_mc() will do uncharge later */
4275                         return -ENOMEM;
4276                 mc.precharge++;
4277         }
4278         return ret;
4279 }
4280
4281 /**
4282  * is_target_pte_for_mc - check a pte whether it is valid for move charge
4283  * @vma: the vma the pte to be checked belongs
4284  * @addr: the address corresponding to the pte to be checked
4285  * @ptent: the pte to be checked
4286  * @target: the pointer the target page or swap ent will be stored(can be NULL)
4287  *
4288  * Returns
4289  *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
4290  *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
4291  *     move charge. if @target is not NULL, the page is stored in target->page
4292  *     with extra refcnt got(Callers should handle it).
4293  *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
4294  *     target for charge migration. if @target is not NULL, the entry is stored
4295  *     in target->ent.
4296  *
4297  * Called with pte lock held.
4298  */
4299 union mc_target {
4300         struct page     *page;
4301         swp_entry_t     ent;
4302 };
4303
4304 enum mc_target_type {
4305         MC_TARGET_NONE, /* not used */
4306         MC_TARGET_PAGE,
4307         MC_TARGET_SWAP,
4308 };
4309
4310 static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
4311                                                 unsigned long addr, pte_t ptent)
4312 {
4313         struct page *page = vm_normal_page(vma, addr, ptent);
4314
4315         if (!page || !page_mapped(page))
4316                 return NULL;
4317         if (PageAnon(page)) {
4318                 /* we don't move shared anon */
4319                 if (!move_anon() || page_mapcount(page) > 2)
4320                         return NULL;
4321         } else if (!move_file())
4322                 /* we ignore mapcount for file pages */
4323                 return NULL;
4324         if (!get_page_unless_zero(page))
4325                 return NULL;
4326
4327         return page;
4328 }
4329
4330 static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
4331                         unsigned long addr, pte_t ptent, swp_entry_t *entry)
4332 {
4333         int usage_count;
4334         struct page *page = NULL;
4335         swp_entry_t ent = pte_to_swp_entry(ptent);
4336
4337         if (!move_anon() || non_swap_entry(ent))
4338                 return NULL;
4339         usage_count = mem_cgroup_count_swap_user(ent, &page);
4340         if (usage_count > 1) { /* we don't move shared anon */
4341                 if (page)
4342                         put_page(page);
4343                 return NULL;
4344         }
4345         if (do_swap_account)
4346                 entry->val = ent.val;
4347
4348         return page;
4349 }
4350
4351 static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
4352                         unsigned long addr, pte_t ptent, swp_entry_t *entry)
4353 {
4354         struct page *page = NULL;
4355         struct inode *inode;
4356         struct address_space *mapping;
4357         pgoff_t pgoff;
4358
4359         if (!vma->vm_file) /* anonymous vma */
4360                 return NULL;
4361         if (!move_file())
4362                 return NULL;
4363
4364         inode = vma->vm_file->f_path.dentry->d_inode;
4365         mapping = vma->vm_file->f_mapping;
4366         if (pte_none(ptent))
4367                 pgoff = linear_page_index(vma, addr);
4368         else /* pte_file(ptent) is true */
4369                 pgoff = pte_to_pgoff(ptent);
4370
4371         /* page is moved even if it's not RSS of this task(page-faulted). */
4372         if (!mapping_cap_swap_backed(mapping)) { /* normal file */
4373                 page = find_get_page(mapping, pgoff);
4374         } else { /* shmem/tmpfs file. we should take account of swap too. */
4375                 swp_entry_t ent;
4376                 mem_cgroup_get_shmem_target(inode, pgoff, &page, &ent);
4377                 if (do_swap_account)
4378                         entry->val = ent.val;
4379         }
4380
4381         return page;
4382 }
4383
4384 static int is_target_pte_for_mc(struct vm_area_struct *vma,
4385                 unsigned long addr, pte_t ptent, union mc_target *target)
4386 {
4387         struct page *page = NULL;
4388         struct page_cgroup *pc;
4389         int ret = 0;
4390         swp_entry_t ent = { .val = 0 };
4391
4392         if (pte_present(ptent))
4393                 page = mc_handle_present_pte(vma, addr, ptent);
4394         else if (is_swap_pte(ptent))
4395                 page = mc_handle_swap_pte(vma, addr, ptent, &ent);
4396         else if (pte_none(ptent) || pte_file(ptent))
4397                 page = mc_handle_file_pte(vma, addr, ptent, &ent);
4398
4399         if (!page && !ent.val)
4400                 return 0;
4401         if (page) {
4402                 pc = lookup_page_cgroup(page);
4403                 /*
4404                  * Do only loose check w/o page_cgroup lock.
4405                  * mem_cgroup_move_account() checks the pc is valid or not under
4406                  * the lock.
4407                  */
4408                 if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
4409                         ret = MC_TARGET_PAGE;
4410                         if (target)
4411                                 target->page = page;
4412                 }
4413                 if (!ret || !target)
4414                         put_page(page);
4415         }
4416         /* There is a swap entry and a page doesn't exist or isn't charged */
4417         if (ent.val && !ret &&
4418                         css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
4419                 ret = MC_TARGET_SWAP;
4420                 if (target)
4421                         target->ent = ent;
4422         }
4423         return ret;
4424 }
4425
4426 static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
4427                                         unsigned long addr, unsigned long end,
4428                                         struct mm_walk *walk)
4429 {
4430         struct vm_area_struct *vma = walk->private;
4431         pte_t *pte;
4432         spinlock_t *ptl;
4433
4434         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4435         for (; addr != end; pte++, addr += PAGE_SIZE)
4436                 if (is_target_pte_for_mc(vma, addr, *pte, NULL))
4437                         mc.precharge++; /* increment precharge temporarily */
4438         pte_unmap_unlock(pte - 1, ptl);
4439         cond_resched();
4440
4441         return 0;
4442 }
4443
4444 static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
4445 {
4446         unsigned long precharge;
4447         struct vm_area_struct *vma;
4448
4449         down_read(&mm->mmap_sem);
4450         for (vma = mm->mmap; vma; vma = vma->vm_next) {
4451                 struct mm_walk mem_cgroup_count_precharge_walk = {
4452                         .pmd_entry = mem_cgroup_count_precharge_pte_range,
4453                         .mm = mm,
4454                         .private = vma,
4455                 };
4456                 if (is_vm_hugetlb_page(vma))
4457                         continue;
4458                 walk_page_range(vma->vm_start, vma->vm_end,
4459                                         &mem_cgroup_count_precharge_walk);
4460         }
4461         up_read(&mm->mmap_sem);
4462
4463         precharge = mc.precharge;
4464         mc.precharge = 0;
4465
4466         return precharge;
4467 }
4468
4469 static int mem_cgroup_precharge_mc(struct mm_struct *mm)
4470 {
4471         return mem_cgroup_do_precharge(mem_cgroup_count_precharge(mm));
4472 }
4473
4474 static void mem_cgroup_clear_mc(void)
4475 {
4476         struct mem_cgroup *from = mc.from;
4477         struct mem_cgroup *to = mc.to;
4478
4479         /* we must uncharge all the leftover precharges from mc.to */
4480         if (mc.precharge) {
4481                 __mem_cgroup_cancel_charge(mc.to, mc.precharge);
4482                 mc.precharge = 0;
4483         }
4484         /*
4485          * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
4486          * we must uncharge here.
4487          */
4488         if (mc.moved_charge) {
4489                 __mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
4490                 mc.moved_charge = 0;
4491         }
4492         /* we must fixup refcnts and charges */
4493         if (mc.moved_swap) {
4494                 /* uncharge swap account from the old cgroup */
4495                 if (!mem_cgroup_is_root(mc.from))
4496                         res_counter_uncharge(&mc.from->memsw,
4497                                                 PAGE_SIZE * mc.moved_swap);
4498                 __mem_cgroup_put(mc.from, mc.moved_swap);
4499
4500                 if (!mem_cgroup_is_root(mc.to)) {
4501                         /*
4502                          * we charged both to->res and to->memsw, so we should
4503                          * uncharge to->res.
4504                          */
4505                         res_counter_uncharge(&mc.to->res,
4506                                                 PAGE_SIZE * mc.moved_swap);
4507                 }
4508                 /* we've already done mem_cgroup_get(mc.to) */
4509
4510                 mc.moved_swap = 0;
4511         }
4512         spin_lock(&mc.lock);
4513         mc.from = NULL;
4514         mc.to = NULL;
4515         mc.moving_task = NULL;
4516         spin_unlock(&mc.lock);
4517         memcg_oom_recover(from);
4518         memcg_oom_recover(to);
4519         wake_up_all(&mc.waitq);
4520 }
4521
4522 static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4523                                 struct cgroup *cgroup,
4524                                 struct task_struct *p,
4525                                 bool threadgroup)
4526 {
4527         int ret = 0;
4528         struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup);
4529
4530         if (mem->move_charge_at_immigrate) {
4531                 struct mm_struct *mm;
4532                 struct mem_cgroup *from = mem_cgroup_from_task(p);
4533
4534                 VM_BUG_ON(from == mem);
4535
4536                 mm = get_task_mm(p);
4537                 if (!mm)
4538                         return 0;
4539                 /* We move charges only when we move a owner of the mm */
4540                 if (mm->owner == p) {
4541                         VM_BUG_ON(mc.from);
4542                         VM_BUG_ON(mc.to);
4543                         VM_BUG_ON(mc.precharge);
4544                         VM_BUG_ON(mc.moved_charge);
4545                         VM_BUG_ON(mc.moved_swap);
4546                         VM_BUG_ON(mc.moving_task);
4547                         spin_lock(&mc.lock);
4548                         mc.from = from;
4549                         mc.to = mem;
4550                         mc.precharge = 0;
4551                         mc.moved_charge = 0;
4552                         mc.moved_swap = 0;
4553                         mc.moving_task = current;
4554                         spin_unlock(&mc.lock);
4555
4556                         ret = mem_cgroup_precharge_mc(mm);
4557                         if (ret)
4558                                 mem_cgroup_clear_mc();
4559                 }
4560                 mmput(mm);
4561         }
4562         return ret;
4563 }
4564
4565 static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4566                                 struct cgroup *cgroup,
4567                                 struct task_struct *p,
4568                                 bool threadgroup)
4569 {
4570         mem_cgroup_clear_mc();
4571 }
4572
4573 static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
4574                                 unsigned long addr, unsigned long end,
4575                                 struct mm_walk *walk)
4576 {
4577         int ret = 0;
4578         struct vm_area_struct *vma = walk->private;
4579         pte_t *pte;
4580         spinlock_t *ptl;
4581
4582 retry:
4583         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4584         for (; addr != end; addr += PAGE_SIZE) {
4585                 pte_t ptent = *(pte++);
4586                 union mc_target target;
4587                 int type;
4588                 struct page *page;
4589                 struct page_cgroup *pc;
4590                 swp_entry_t ent;
4591
4592                 if (!mc.precharge)
4593                         break;
4594
4595                 type = is_target_pte_for_mc(vma, addr, ptent, &target);
4596                 switch (type) {
4597                 case MC_TARGET_PAGE:
4598                         page = target.page;
4599                         if (isolate_lru_page(page))
4600                                 goto put;
4601                         pc = lookup_page_cgroup(page);
4602                         if (!mem_cgroup_move_account(pc,
4603                                                 mc.from, mc.to, false)) {
4604                                 mc.precharge--;
4605                                 /* we uncharge from mc.from later. */
4606                                 mc.moved_charge++;
4607                         }
4608                         putback_lru_page(page);
4609 put:                    /* is_target_pte_for_mc() gets the page */
4610                         put_page(page);
4611                         break;
4612                 case MC_TARGET_SWAP:
4613                         ent = target.ent;
4614                         if (!mem_cgroup_move_swap_account(ent,
4615                                                 mc.from, mc.to, false)) {
4616                                 mc.precharge--;
4617                                 /* we fixup refcnts and charges later. */
4618                                 mc.moved_swap++;
4619                         }
4620                         break;
4621                 default:
4622                         break;
4623                 }
4624         }
4625         pte_unmap_unlock(pte - 1, ptl);
4626         cond_resched();
4627
4628         if (addr != end) {
4629                 /*
4630                  * We have consumed all precharges we got in can_attach().
4631                  * We try charge one by one, but don't do any additional
4632                  * charges to mc.to if we have failed in charge once in attach()
4633                  * phase.
4634                  */
4635                 ret = mem_cgroup_do_precharge(1);
4636                 if (!ret)
4637                         goto retry;
4638         }
4639
4640         return ret;
4641 }
4642
4643 static void mem_cgroup_move_charge(struct mm_struct *mm)
4644 {
4645         struct vm_area_struct *vma;
4646
4647         lru_add_drain_all();
4648         down_read(&mm->mmap_sem);
4649         for (vma = mm->mmap; vma; vma = vma->vm_next) {
4650                 int ret;
4651                 struct mm_walk mem_cgroup_move_charge_walk = {
4652                         .pmd_entry = mem_cgroup_move_charge_pte_range,
4653                         .mm = mm,
4654                         .private = vma,
4655                 };
4656                 if (is_vm_hugetlb_page(vma))
4657                         continue;
4658                 ret = walk_page_range(vma->vm_start, vma->vm_end,
4659                                                 &mem_cgroup_move_charge_walk);
4660                 if (ret)
4661                         /*
4662                          * means we have consumed all precharges and failed in
4663                          * doing additional charge. Just abandon here.
4664                          */
4665                         break;
4666         }
4667         up_read(&mm->mmap_sem);
4668 }
4669
4670 static void mem_cgroup_move_task(struct cgroup_subsys *ss,
4671                                 struct cgroup *cont,
4672                                 struct cgroup *old_cont,
4673                                 struct task_struct *p,
4674                                 bool threadgroup)
4675 {
4676         struct mm_struct *mm;
4677
4678         if (!mc.to)
4679                 /* no need to move charge */
4680                 return;
4681
4682         mm = get_task_mm(p);
4683         if (mm) {
4684                 mem_cgroup_move_charge(mm);
4685                 mmput(mm);
4686         }
4687         mem_cgroup_clear_mc();
4688 }
4689 #else   /* !CONFIG_MMU */
4690 static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4691                                 struct cgroup *cgroup,
4692                                 struct task_struct *p,
4693                                 bool threadgroup)
4694 {
4695         return 0;
4696 }
4697 static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4698                                 struct cgroup *cgroup,
4699                                 struct task_struct *p,
4700                                 bool threadgroup)
4701 {
4702 }
4703 static void mem_cgroup_move_task(struct cgroup_subsys *ss,
4704                                 struct cgroup *cont,
4705                                 struct cgroup *old_cont,
4706                                 struct task_struct *p,
4707                                 bool threadgroup)
4708 {
4709 }
4710 #endif
4711
4712 struct cgroup_subsys mem_cgroup_subsys = {
4713         .name = "memory",
4714         .subsys_id = mem_cgroup_subsys_id,
4715         .create = mem_cgroup_create,
4716         .pre_destroy = mem_cgroup_pre_destroy,
4717         .destroy = mem_cgroup_destroy,
4718         .populate = mem_cgroup_populate,
4719         .can_attach = mem_cgroup_can_attach,
4720         .cancel_attach = mem_cgroup_cancel_attach,
4721         .attach = mem_cgroup_move_task,
4722         .early_init = 0,
4723         .use_id = 1,
4724 };
4725
4726 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4727
4728 static int __init disable_swap_account(char *s)
4729 {
4730         really_do_swap_account = 0;
4731         return 1;
4732 }
4733 __setup("noswapaccount", disable_swap_account);
4734 #endif