linux/mm/memcontrol.c
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   1/* memcontrol.c - Memory Controller
   2 *
   3 * Copyright IBM Corporation, 2007
   4 * Author Balbir Singh <balbir@linux.vnet.ibm.com>
   5 *
   6 * Copyright 2007 OpenVZ SWsoft Inc
   7 * Author: Pavel Emelianov <xemul@openvz.org>
   8 *
   9 * Memory thresholds
  10 * Copyright (C) 2009 Nokia Corporation
  11 * Author: Kirill A. Shutemov
  12 *
  13 * This program is free software; you can redistribute it and/or modify
  14 * it under the terms of the GNU General Public License as published by
  15 * the Free Software Foundation; either version 2 of the License, or
  16 * (at your option) any later version.
  17 *
  18 * This program is distributed in the hope that it will be useful,
  19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 * GNU General Public License for more details.
  22 */
  23
  24#include <linux/res_counter.h>
  25#include <linux/memcontrol.h>
  26#include <linux/cgroup.h>
  27#include <linux/mm.h>
  28#include <linux/hugetlb.h>
  29#include <linux/pagemap.h>
  30#include <linux/smp.h>
  31#include <linux/page-flags.h>
  32#include <linux/backing-dev.h>
  33#include <linux/bit_spinlock.h>
  34#include <linux/rcupdate.h>
  35#include <linux/limits.h>
  36#include <linux/mutex.h>
  37#include <linux/rbtree.h>
  38#include <linux/slab.h>
  39#include <linux/swap.h>
  40#include <linux/swapops.h>
  41#include <linux/spinlock.h>
  42#include <linux/eventfd.h>
  43#include <linux/sort.h>
  44#include <linux/fs.h>
  45#include <linux/seq_file.h>
  46#include <linux/vmalloc.h>
  47#include <linux/mm_inline.h>
  48#include <linux/page_cgroup.h>
  49#include <linux/cpu.h>
  50#include <linux/oom.h>
  51#include "internal.h"
  52
  53#include <asm/uaccess.h>
  54
  55#include <trace/events/vmscan.h>
  56
  57struct cgroup_subsys mem_cgroup_subsys __read_mostly;
  58#define MEM_CGROUP_RECLAIM_RETRIES      5
  59struct mem_cgroup *root_mem_cgroup __read_mostly;
  60
  61#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
  62/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
  63int do_swap_account __read_mostly;
  64
  65/* for remember boot option*/
  66#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED
  67static int really_do_swap_account __initdata = 1;
  68#else
  69static int really_do_swap_account __initdata = 0;
  70#endif
  71
  72#else
  73#define do_swap_account         (0)
  74#endif
  75
  76/*
  77 * Per memcg event counter is incremented at every pagein/pageout. This counter
  78 * is used for trigger some periodic events. This is straightforward and better
  79 * than using jiffies etc. to handle periodic memcg event.
  80 *
  81 * These values will be used as !((event) & ((1 <<(thresh)) - 1))
  82 */
  83#define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
  84#define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
  85
  86/*
  87 * Statistics for memory cgroup.
  88 */
  89enum mem_cgroup_stat_index {
  90        /*
  91         * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
  92         */
  93        MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
  94        MEM_CGROUP_STAT_RSS,       /* # of pages charged as anon rss */
  95        MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
  96        MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
  97        MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
  98        MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
  99        MEM_CGROUP_STAT_DATA, /* end of data requires synchronization */
 100        /* incremented at every  pagein/pageout */
 101        MEM_CGROUP_EVENTS = MEM_CGROUP_STAT_DATA,
 102        MEM_CGROUP_ON_MOVE,     /* someone is moving account between groups */
 103
 104        MEM_CGROUP_STAT_NSTATS,
 105};
 106
 107struct mem_cgroup_stat_cpu {
 108        s64 count[MEM_CGROUP_STAT_NSTATS];
 109};
 110
 111/*
 112 * per-zone information in memory controller.
 113 */
 114struct mem_cgroup_per_zone {
 115        /*
 116         * spin_lock to protect the per cgroup LRU
 117         */
 118        struct list_head        lists[NR_LRU_LISTS];
 119        unsigned long           count[NR_LRU_LISTS];
 120
 121        struct zone_reclaim_stat reclaim_stat;
 122        struct rb_node          tree_node;      /* RB tree node */
 123        unsigned long long      usage_in_excess;/* Set to the value by which */
 124                                                /* the soft limit is exceeded*/
 125        bool                    on_tree;
 126        struct mem_cgroup       *mem;           /* Back pointer, we cannot */
 127                                                /* use container_of        */
 128};
 129/* Macro for accessing counter */
 130#define MEM_CGROUP_ZSTAT(mz, idx)       ((mz)->count[(idx)])
 131
 132struct mem_cgroup_per_node {
 133        struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
 134};
 135
 136struct mem_cgroup_lru_info {
 137        struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
 138};
 139
 140/*
 141 * Cgroups above their limits are maintained in a RB-Tree, independent of
 142 * their hierarchy representation
 143 */
 144
 145struct mem_cgroup_tree_per_zone {
 146        struct rb_root rb_root;
 147        spinlock_t lock;
 148};
 149
 150struct mem_cgroup_tree_per_node {
 151        struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
 152};
 153
 154struct mem_cgroup_tree {
 155        struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
 156};
 157
 158static struct mem_cgroup_tree soft_limit_tree __read_mostly;
 159
 160struct mem_cgroup_threshold {
 161        struct eventfd_ctx *eventfd;
 162        u64 threshold;
 163};
 164
 165/* For threshold */
 166struct mem_cgroup_threshold_ary {
 167        /* An array index points to threshold just below usage. */
 168        int current_threshold;
 169        /* Size of entries[] */
 170        unsigned int size;
 171        /* Array of thresholds */
 172        struct mem_cgroup_threshold entries[0];
 173};
 174
 175struct mem_cgroup_thresholds {
 176        /* Primary thresholds array */
 177        struct mem_cgroup_threshold_ary *primary;
 178        /*
 179         * Spare threshold array.
 180         * This is needed to make mem_cgroup_unregister_event() "never fail".
 181         * It must be able to store at least primary->size - 1 entries.
 182         */
 183        struct mem_cgroup_threshold_ary *spare;
 184};
 185
 186/* for OOM */
 187struct mem_cgroup_eventfd_list {
 188        struct list_head list;
 189        struct eventfd_ctx *eventfd;
 190};
 191
 192static void mem_cgroup_threshold(struct mem_cgroup *mem);
 193static void mem_cgroup_oom_notify(struct mem_cgroup *mem);
 194
 195/*
 196 * The memory controller data structure. The memory controller controls both
 197 * page cache and RSS per cgroup. We would eventually like to provide
 198 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
 199 * to help the administrator determine what knobs to tune.
 200 *
 201 * TODO: Add a water mark for the memory controller. Reclaim will begin when
 202 * we hit the water mark. May be even add a low water mark, such that
 203 * no reclaim occurs from a cgroup at it's low water mark, this is
 204 * a feature that will be implemented much later in the future.
 205 */
 206struct mem_cgroup {
 207        struct cgroup_subsys_state css;
 208        /*
 209         * the counter to account for memory usage
 210         */
 211        struct res_counter res;
 212        /*
 213         * the counter to account for mem+swap usage.
 214         */
 215        struct res_counter memsw;
 216        /*
 217         * Per cgroup active and inactive list, similar to the
 218         * per zone LRU lists.
 219         */
 220        struct mem_cgroup_lru_info info;
 221
 222        /*
 223          protect against reclaim related member.
 224        */
 225        spinlock_t reclaim_param_lock;
 226
 227        /*
 228         * While reclaiming in a hierarchy, we cache the last child we
 229         * reclaimed from.
 230         */
 231        int last_scanned_child;
 232        /*
 233         * Should the accounting and control be hierarchical, per subtree?
 234         */
 235        bool use_hierarchy;
 236        atomic_t        oom_lock;
 237        atomic_t        refcnt;
 238
 239        unsigned int    swappiness;
 240        /* OOM-Killer disable */
 241        int             oom_kill_disable;
 242
 243        /* set when res.limit == memsw.limit */
 244        bool            memsw_is_minimum;
 245
 246        /* protect arrays of thresholds */
 247        struct mutex thresholds_lock;
 248
 249        /* thresholds for memory usage. RCU-protected */
 250        struct mem_cgroup_thresholds thresholds;
 251
 252        /* thresholds for mem+swap usage. RCU-protected */
 253        struct mem_cgroup_thresholds memsw_thresholds;
 254
 255        /* For oom notifier event fd */
 256        struct list_head oom_notify;
 257
 258        /*
 259         * Should we move charges of a task when a task is moved into this
 260         * mem_cgroup ? And what type of charges should we move ?
 261         */
 262        unsigned long   move_charge_at_immigrate;
 263        /*
 264         * percpu counter.
 265         */
 266        struct mem_cgroup_stat_cpu *stat;
 267        /*
 268         * used when a cpu is offlined or other synchronizations
 269         * See mem_cgroup_read_stat().
 270         */
 271        struct mem_cgroup_stat_cpu nocpu_base;
 272        spinlock_t pcp_counter_lock;
 273};
 274
 275/* Stuffs for move charges at task migration. */
 276/*
 277 * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
 278 * left-shifted bitmap of these types.
 279 */
 280enum move_type {
 281        MOVE_CHARGE_TYPE_ANON,  /* private anonymous page and swap of it */
 282        MOVE_CHARGE_TYPE_FILE,  /* file page(including tmpfs) and swap of it */
 283        NR_MOVE_TYPE,
 284};
 285
 286/* "mc" and its members are protected by cgroup_mutex */
 287static struct move_charge_struct {
 288        spinlock_t        lock; /* for from, to */
 289        struct mem_cgroup *from;
 290        struct mem_cgroup *to;
 291        unsigned long precharge;
 292        unsigned long moved_charge;
 293        unsigned long moved_swap;
 294        struct task_struct *moving_task;        /* a task moving charges */
 295        wait_queue_head_t waitq;                /* a waitq for other context */
 296} mc = {
 297        .lock = __SPIN_LOCK_UNLOCKED(mc.lock),
 298        .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
 299};
 300
 301static bool move_anon(void)
 302{
 303        return test_bit(MOVE_CHARGE_TYPE_ANON,
 304                                        &mc.to->move_charge_at_immigrate);
 305}
 306
 307static bool move_file(void)
 308{
 309        return test_bit(MOVE_CHARGE_TYPE_FILE,
 310                                        &mc.to->move_charge_at_immigrate);
 311}
 312
 313/*
 314 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
 315 * limit reclaim to prevent infinite loops, if they ever occur.
 316 */
 317#define MEM_CGROUP_MAX_RECLAIM_LOOPS            (100)
 318#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2)
 319
 320enum charge_type {
 321        MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
 322        MEM_CGROUP_CHARGE_TYPE_MAPPED,
 323        MEM_CGROUP_CHARGE_TYPE_SHMEM,   /* used by page migration of shmem */
 324        MEM_CGROUP_CHARGE_TYPE_FORCE,   /* used by force_empty */
 325        MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
 326        MEM_CGROUP_CHARGE_TYPE_DROP,    /* a page was unused swap cache */
 327        NR_CHARGE_TYPE,
 328};
 329
 330/* only for here (for easy reading.) */
 331#define PCGF_CACHE      (1UL << PCG_CACHE)
 332#define PCGF_USED       (1UL << PCG_USED)
 333#define PCGF_LOCK       (1UL << PCG_LOCK)
 334/* Not used, but added here for completeness */
 335#define PCGF_ACCT       (1UL << PCG_ACCT)
 336
 337/* for encoding cft->private value on file */
 338#define _MEM                    (0)
 339#define _MEMSWAP                (1)
 340#define _OOM_TYPE               (2)
 341#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
 342#define MEMFILE_TYPE(val)       (((val) >> 16) & 0xffff)
 343#define MEMFILE_ATTR(val)       ((val) & 0xffff)
 344/* Used for OOM nofiier */
 345#define OOM_CONTROL             (0)
 346
 347/*
 348 * Reclaim flags for mem_cgroup_hierarchical_reclaim
 349 */
 350#define MEM_CGROUP_RECLAIM_NOSWAP_BIT   0x0
 351#define MEM_CGROUP_RECLAIM_NOSWAP       (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
 352#define MEM_CGROUP_RECLAIM_SHRINK_BIT   0x1
 353#define MEM_CGROUP_RECLAIM_SHRINK       (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
 354#define MEM_CGROUP_RECLAIM_SOFT_BIT     0x2
 355#define MEM_CGROUP_RECLAIM_SOFT         (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
 356
 357static void mem_cgroup_get(struct mem_cgroup *mem);
 358static void mem_cgroup_put(struct mem_cgroup *mem);
 359static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
 360static void drain_all_stock_async(void);
 361
 362static struct mem_cgroup_per_zone *
 363mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
 364{
 365        return &mem->info.nodeinfo[nid]->zoneinfo[zid];
 366}
 367
 368struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
 369{
 370        return &mem->css;
 371}
 372
 373static struct mem_cgroup_per_zone *
 374page_cgroup_zoneinfo(struct page_cgroup *pc)
 375{
 376        struct mem_cgroup *mem = pc->mem_cgroup;
 377        int nid = page_cgroup_nid(pc);
 378        int zid = page_cgroup_zid(pc);
 379
 380        if (!mem)
 381                return NULL;
 382
 383        return mem_cgroup_zoneinfo(mem, nid, zid);
 384}
 385
 386static struct mem_cgroup_tree_per_zone *
 387soft_limit_tree_node_zone(int nid, int zid)
 388{
 389        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
 390}
 391
 392static struct mem_cgroup_tree_per_zone *
 393soft_limit_tree_from_page(struct page *page)
 394{
 395        int nid = page_to_nid(page);
 396        int zid = page_zonenum(page);
 397
 398        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
 399}
 400
 401static void
 402__mem_cgroup_insert_exceeded(struct mem_cgroup *mem,
 403                                struct mem_cgroup_per_zone *mz,
 404                                struct mem_cgroup_tree_per_zone *mctz,
 405                                unsigned long long new_usage_in_excess)
 406{
 407        struct rb_node **p = &mctz->rb_root.rb_node;
 408        struct rb_node *parent = NULL;
 409        struct mem_cgroup_per_zone *mz_node;
 410
 411        if (mz->on_tree)
 412                return;
 413
 414        mz->usage_in_excess = new_usage_in_excess;
 415        if (!mz->usage_in_excess)
 416                return;
 417        while (*p) {
 418                parent = *p;
 419                mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
 420                                        tree_node);
 421                if (mz->usage_in_excess < mz_node->usage_in_excess)
 422                        p = &(*p)->rb_left;
 423                /*
 424                 * We can't avoid mem cgroups that are over their soft
 425                 * limit by the same amount
 426                 */
 427                else if (mz->usage_in_excess >= mz_node->usage_in_excess)
 428                        p = &(*p)->rb_right;
 429        }
 430        rb_link_node(&mz->tree_node, parent, p);
 431        rb_insert_color(&mz->tree_node, &mctz->rb_root);
 432        mz->on_tree = true;
 433}
 434
 435static void
 436__mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
 437                                struct mem_cgroup_per_zone *mz,
 438                                struct mem_cgroup_tree_per_zone *mctz)
 439{
 440        if (!mz->on_tree)
 441                return;
 442        rb_erase(&mz->tree_node, &mctz->rb_root);
 443        mz->on_tree = false;
 444}
 445
 446static void
 447mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
 448                                struct mem_cgroup_per_zone *mz,
 449                                struct mem_cgroup_tree_per_zone *mctz)
 450{
 451        spin_lock(&mctz->lock);
 452        __mem_cgroup_remove_exceeded(mem, mz, mctz);
 453        spin_unlock(&mctz->lock);
 454}
 455
 456
 457static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
 458{
 459        unsigned long long excess;
 460        struct mem_cgroup_per_zone *mz;
 461        struct mem_cgroup_tree_per_zone *mctz;
 462        int nid = page_to_nid(page);
 463        int zid = page_zonenum(page);
 464        mctz = soft_limit_tree_from_page(page);
 465
 466        /*
 467         * Necessary to update all ancestors when hierarchy is used.
 468         * because their event counter is not touched.
 469         */
 470        for (; mem; mem = parent_mem_cgroup(mem)) {
 471                mz = mem_cgroup_zoneinfo(mem, nid, zid);
 472                excess = res_counter_soft_limit_excess(&mem->res);
 473                /*
 474                 * We have to update the tree if mz is on RB-tree or
 475                 * mem is over its softlimit.
 476                 */
 477                if (excess || mz->on_tree) {
 478                        spin_lock(&mctz->lock);
 479                        /* if on-tree, remove it */
 480                        if (mz->on_tree)
 481                                __mem_cgroup_remove_exceeded(mem, mz, mctz);
 482                        /*
 483                         * Insert again. mz->usage_in_excess will be updated.
 484                         * If excess is 0, no tree ops.
 485                         */
 486                        __mem_cgroup_insert_exceeded(mem, mz, mctz, excess);
 487                        spin_unlock(&mctz->lock);
 488                }
 489        }
 490}
 491
 492static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
 493{
 494        int node, zone;
 495        struct mem_cgroup_per_zone *mz;
 496        struct mem_cgroup_tree_per_zone *mctz;
 497
 498        for_each_node_state(node, N_POSSIBLE) {
 499                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
 500                        mz = mem_cgroup_zoneinfo(mem, node, zone);
 501                        mctz = soft_limit_tree_node_zone(node, zone);
 502                        mem_cgroup_remove_exceeded(mem, mz, mctz);
 503                }
 504        }
 505}
 506
 507static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
 508{
 509        return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
 510}
 511
 512static struct mem_cgroup_per_zone *
 513__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 514{
 515        struct rb_node *rightmost = NULL;
 516        struct mem_cgroup_per_zone *mz;
 517
 518retry:
 519        mz = NULL;
 520        rightmost = rb_last(&mctz->rb_root);
 521        if (!rightmost)
 522                goto done;              /* Nothing to reclaim from */
 523
 524        mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
 525        /*
 526         * Remove the node now but someone else can add it back,
 527         * we will to add it back at the end of reclaim to its correct
 528         * position in the tree.
 529         */
 530        __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
 531        if (!res_counter_soft_limit_excess(&mz->mem->res) ||
 532                !css_tryget(&mz->mem->css))
 533                goto retry;
 534done:
 535        return mz;
 536}
 537
 538static struct mem_cgroup_per_zone *
 539mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 540{
 541        struct mem_cgroup_per_zone *mz;
 542
 543        spin_lock(&mctz->lock);
 544        mz = __mem_cgroup_largest_soft_limit_node(mctz);
 545        spin_unlock(&mctz->lock);
 546        return mz;
 547}
 548
 549/*
 550 * Implementation Note: reading percpu statistics for memcg.
 551 *
 552 * Both of vmstat[] and percpu_counter has threshold and do periodic
 553 * synchronization to implement "quick" read. There are trade-off between
 554 * reading cost and precision of value. Then, we may have a chance to implement
 555 * a periodic synchronizion of counter in memcg's counter.
 556 *
 557 * But this _read() function is used for user interface now. The user accounts
 558 * memory usage by memory cgroup and he _always_ requires exact value because
 559 * he accounts memory. Even if we provide quick-and-fuzzy read, we always
 560 * have to visit all online cpus and make sum. So, for now, unnecessary
 561 * synchronization is not implemented. (just implemented for cpu hotplug)
 562 *
 563 * If there are kernel internal actions which can make use of some not-exact
 564 * value, and reading all cpu value can be performance bottleneck in some
 565 * common workload, threashold and synchonization as vmstat[] should be
 566 * implemented.
 567 */
 568static s64 mem_cgroup_read_stat(struct mem_cgroup *mem,
 569                enum mem_cgroup_stat_index idx)
 570{
 571        int cpu;
 572        s64 val = 0;
 573
 574        get_online_cpus();
 575        for_each_online_cpu(cpu)
 576                val += per_cpu(mem->stat->count[idx], cpu);
 577#ifdef CONFIG_HOTPLUG_CPU
 578        spin_lock(&mem->pcp_counter_lock);
 579        val += mem->nocpu_base.count[idx];
 580        spin_unlock(&mem->pcp_counter_lock);
 581#endif
 582        put_online_cpus();
 583        return val;
 584}
 585
 586static s64 mem_cgroup_local_usage(struct mem_cgroup *mem)
 587{
 588        s64 ret;
 589
 590        ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
 591        ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
 592        return ret;
 593}
 594
 595static void mem_cgroup_swap_statistics(struct mem_cgroup *mem,
 596                                         bool charge)
 597{
 598        int val = (charge) ? 1 : -1;
 599        this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
 600}
 601
 602static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
 603                                         bool file, int nr_pages)
 604{
 605        preempt_disable();
 606
 607        if (file)
 608                __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_CACHE], nr_pages);
 609        else
 610                __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_RSS], nr_pages);
 611
 612        /* pagein of a big page is an event. So, ignore page size */
 613        if (nr_pages > 0)
 614                __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
 615        else {
 616                __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
 617                nr_pages = -nr_pages; /* for event */
 618        }
 619
 620        __this_cpu_add(mem->stat->count[MEM_CGROUP_EVENTS], nr_pages);
 621
 622        preempt_enable();
 623}
 624
 625static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
 626                                        enum lru_list idx)
 627{
 628        int nid, zid;
 629        struct mem_cgroup_per_zone *mz;
 630        u64 total = 0;
 631
 632        for_each_online_node(nid)
 633                for (zid = 0; zid < MAX_NR_ZONES; zid++) {
 634                        mz = mem_cgroup_zoneinfo(mem, nid, zid);
 635                        total += MEM_CGROUP_ZSTAT(mz, idx);
 636                }
 637        return total;
 638}
 639
 640static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
 641{
 642        s64 val;
 643
 644        val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
 645
 646        return !(val & ((1 << event_mask_shift) - 1));
 647}
 648
 649/*
 650 * Check events in order.
 651 *
 652 */
 653static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
 654{
 655        /* threshold event is triggered in finer grain than soft limit */
 656        if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
 657                mem_cgroup_threshold(mem);
 658                if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
 659                        mem_cgroup_update_tree(mem, page);
 660        }
 661}
 662
 663static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 664{
 665        return container_of(cgroup_subsys_state(cont,
 666                                mem_cgroup_subsys_id), struct mem_cgroup,
 667                                css);
 668}
 669
 670struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 671{
 672        /*
 673         * mm_update_next_owner() may clear mm->owner to NULL
 674         * if it races with swapoff, page migration, etc.
 675         * So this can be called with p == NULL.
 676         */
 677        if (unlikely(!p))
 678                return NULL;
 679
 680        return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
 681                                struct mem_cgroup, css);
 682}
 683
 684static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 685{
 686        struct mem_cgroup *mem = NULL;
 687
 688        if (!mm)
 689                return NULL;
 690        /*
 691         * Because we have no locks, mm->owner's may be being moved to other
 692         * cgroup. We use css_tryget() here even if this looks
 693         * pessimistic (rather than adding locks here).
 694         */
 695        rcu_read_lock();
 696        do {
 697                mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
 698                if (unlikely(!mem))
 699                        break;
 700        } while (!css_tryget(&mem->css));
 701        rcu_read_unlock();
 702        return mem;
 703}
 704
 705/* The caller has to guarantee "mem" exists before calling this */
 706static struct mem_cgroup *mem_cgroup_start_loop(struct mem_cgroup *mem)
 707{
 708        struct cgroup_subsys_state *css;
 709        int found;
 710
 711        if (!mem) /* ROOT cgroup has the smallest ID */
 712                return root_mem_cgroup; /*css_put/get against root is ignored*/
 713        if (!mem->use_hierarchy) {
 714                if (css_tryget(&mem->css))
 715                        return mem;
 716                return NULL;
 717        }
 718        rcu_read_lock();
 719        /*
 720         * searching a memory cgroup which has the smallest ID under given
 721         * ROOT cgroup. (ID >= 1)
 722         */
 723        css = css_get_next(&mem_cgroup_subsys, 1, &mem->css, &found);
 724        if (css && css_tryget(css))
 725                mem = container_of(css, struct mem_cgroup, css);
 726        else
 727                mem = NULL;
 728        rcu_read_unlock();
 729        return mem;
 730}
 731
 732static struct mem_cgroup *mem_cgroup_get_next(struct mem_cgroup *iter,
 733                                        struct mem_cgroup *root,
 734                                        bool cond)
 735{
 736        int nextid = css_id(&iter->css) + 1;
 737        int found;
 738        int hierarchy_used;
 739        struct cgroup_subsys_state *css;
 740
 741        hierarchy_used = iter->use_hierarchy;
 742
 743        css_put(&iter->css);
 744        /* If no ROOT, walk all, ignore hierarchy */
 745        if (!cond || (root && !hierarchy_used))
 746                return NULL;
 747
 748        if (!root)
 749                root = root_mem_cgroup;
 750
 751        do {
 752                iter = NULL;
 753                rcu_read_lock();
 754
 755                css = css_get_next(&mem_cgroup_subsys, nextid,
 756                                &root->css, &found);
 757                if (css && css_tryget(css))
 758                        iter = container_of(css, struct mem_cgroup, css);
 759                rcu_read_unlock();
 760                /* If css is NULL, no more cgroups will be found */
 761                nextid = found + 1;
 762        } while (css && !iter);
 763
 764        return iter;
 765}
 766/*
 767 * for_eacn_mem_cgroup_tree() for visiting all cgroup under tree. Please
 768 * be careful that "break" loop is not allowed. We have reference count.
 769 * Instead of that modify "cond" to be false and "continue" to exit the loop.
 770 */
 771#define for_each_mem_cgroup_tree_cond(iter, root, cond) \
 772        for (iter = mem_cgroup_start_loop(root);\
 773             iter != NULL;\
 774             iter = mem_cgroup_get_next(iter, root, cond))
 775
 776#define for_each_mem_cgroup_tree(iter, root) \
 777        for_each_mem_cgroup_tree_cond(iter, root, true)
 778
 779#define for_each_mem_cgroup_all(iter) \
 780        for_each_mem_cgroup_tree_cond(iter, NULL, true)
 781
 782
 783static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
 784{
 785        return (mem == root_mem_cgroup);
 786}
 787
 788/*
 789 * Following LRU functions are allowed to be used without PCG_LOCK.
 790 * Operations are called by routine of global LRU independently from memcg.
 791 * What we have to take care of here is validness of pc->mem_cgroup.
 792 *
 793 * Changes to pc->mem_cgroup happens when
 794 * 1. charge
 795 * 2. moving account
 796 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
 797 * It is added to LRU before charge.
 798 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
 799 * When moving account, the page is not on LRU. It's isolated.
 800 */
 801
 802void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
 803{
 804        struct page_cgroup *pc;
 805        struct mem_cgroup_per_zone *mz;
 806
 807        if (mem_cgroup_disabled())
 808                return;
 809        pc = lookup_page_cgroup(page);
 810        /* can happen while we handle swapcache. */
 811        if (!TestClearPageCgroupAcctLRU(pc))
 812                return;
 813        VM_BUG_ON(!pc->mem_cgroup);
 814        /*
 815         * We don't check PCG_USED bit. It's cleared when the "page" is finally
 816         * removed from global LRU.
 817         */
 818        mz = page_cgroup_zoneinfo(pc);
 819        /* huge page split is done under lru_lock. so, we have no races. */
 820        MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
 821        if (mem_cgroup_is_root(pc->mem_cgroup))
 822                return;
 823        VM_BUG_ON(list_empty(&pc->lru));
 824        list_del_init(&pc->lru);
 825}
 826
 827void mem_cgroup_del_lru(struct page *page)
 828{
 829        mem_cgroup_del_lru_list(page, page_lru(page));
 830}
 831
 832void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
 833{
 834        struct mem_cgroup_per_zone *mz;
 835        struct page_cgroup *pc;
 836
 837        if (mem_cgroup_disabled())
 838                return;
 839
 840        pc = lookup_page_cgroup(page);
 841        /* unused or root page is not rotated. */
 842        if (!PageCgroupUsed(pc))
 843                return;
 844        /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
 845        smp_rmb();
 846        if (mem_cgroup_is_root(pc->mem_cgroup))
 847                return;
 848        mz = page_cgroup_zoneinfo(pc);
 849        list_move(&pc->lru, &mz->lists[lru]);
 850}
 851
 852void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
 853{
 854        struct page_cgroup *pc;
 855        struct mem_cgroup_per_zone *mz;
 856
 857        if (mem_cgroup_disabled())
 858                return;
 859        pc = lookup_page_cgroup(page);
 860        VM_BUG_ON(PageCgroupAcctLRU(pc));
 861        if (!PageCgroupUsed(pc))
 862                return;
 863        /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
 864        smp_rmb();
 865        mz = page_cgroup_zoneinfo(pc);
 866        /* huge page split is done under lru_lock. so, we have no races. */
 867        MEM_CGROUP_ZSTAT(mz, lru) += 1 << compound_order(page);
 868        SetPageCgroupAcctLRU(pc);
 869        if (mem_cgroup_is_root(pc->mem_cgroup))
 870                return;
 871        list_add(&pc->lru, &mz->lists[lru]);
 872}
 873
 874/*
 875 * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
 876 * lru because the page may.be reused after it's fully uncharged (because of
 877 * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
 878 * it again. This function is only used to charge SwapCache. It's done under
 879 * lock_page and expected that zone->lru_lock is never held.
 880 */
 881static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
 882{
 883        unsigned long flags;
 884        struct zone *zone = page_zone(page);
 885        struct page_cgroup *pc = lookup_page_cgroup(page);
 886
 887        spin_lock_irqsave(&zone->lru_lock, flags);
 888        /*
 889         * Forget old LRU when this page_cgroup is *not* used. This Used bit
 890         * is guarded by lock_page() because the page is SwapCache.
 891         */
 892        if (!PageCgroupUsed(pc))
 893                mem_cgroup_del_lru_list(page, page_lru(page));
 894        spin_unlock_irqrestore(&zone->lru_lock, flags);
 895}
 896
 897static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
 898{
 899        unsigned long flags;
 900        struct zone *zone = page_zone(page);
 901        struct page_cgroup *pc = lookup_page_cgroup(page);
 902
 903        spin_lock_irqsave(&zone->lru_lock, flags);
 904        /* link when the page is linked to LRU but page_cgroup isn't */
 905        if (PageLRU(page) && !PageCgroupAcctLRU(pc))
 906                mem_cgroup_add_lru_list(page, page_lru(page));
 907        spin_unlock_irqrestore(&zone->lru_lock, flags);
 908}
 909
 910
 911void mem_cgroup_move_lists(struct page *page,
 912                           enum lru_list from, enum lru_list to)
 913{
 914        if (mem_cgroup_disabled())
 915                return;
 916        mem_cgroup_del_lru_list(page, from);
 917        mem_cgroup_add_lru_list(page, to);
 918}
 919
 920int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
 921{
 922        int ret;
 923        struct mem_cgroup *curr = NULL;
 924        struct task_struct *p;
 925
 926        p = find_lock_task_mm(task);
 927        if (!p)
 928                return 0;
 929        curr = try_get_mem_cgroup_from_mm(p->mm);
 930        task_unlock(p);
 931        if (!curr)
 932                return 0;
 933        /*
 934         * We should check use_hierarchy of "mem" not "curr". Because checking
 935         * use_hierarchy of "curr" here make this function true if hierarchy is
 936         * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
 937         * hierarchy(even if use_hierarchy is disabled in "mem").
 938         */
 939        if (mem->use_hierarchy)
 940                ret = css_is_ancestor(&curr->css, &mem->css);
 941        else
 942                ret = (curr == mem);
 943        css_put(&curr->css);
 944        return ret;
 945}
 946
 947static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
 948{
 949        unsigned long active;
 950        unsigned long inactive;
 951        unsigned long gb;
 952        unsigned long inactive_ratio;
 953
 954        inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_ANON);
 955        active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_ANON);
 956
 957        gb = (inactive + active) >> (30 - PAGE_SHIFT);
 958        if (gb)
 959                inactive_ratio = int_sqrt(10 * gb);
 960        else
 961                inactive_ratio = 1;
 962
 963        if (present_pages) {
 964                present_pages[0] = inactive;
 965                present_pages[1] = active;
 966        }
 967
 968        return inactive_ratio;
 969}
 970
 971int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
 972{
 973        unsigned long active;
 974        unsigned long inactive;
 975        unsigned long present_pages[2];
 976        unsigned long inactive_ratio;
 977
 978        inactive_ratio = calc_inactive_ratio(memcg, present_pages);
 979
 980        inactive = present_pages[0];
 981        active = present_pages[1];
 982
 983        if (inactive * inactive_ratio < active)
 984                return 1;
 985
 986        return 0;
 987}
 988
 989int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
 990{
 991        unsigned long active;
 992        unsigned long inactive;
 993
 994        inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE);
 995        active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE);
 996
 997        return (active > inactive);
 998}
 999
1000unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
1001                                       struct zone *zone,
1002                                       enum lru_list lru)
1003{
1004        int nid = zone_to_nid(zone);
1005        int zid = zone_idx(zone);
1006        struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
1007
1008        return MEM_CGROUP_ZSTAT(mz, lru);
1009}
1010
1011struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
1012                                                      struct zone *zone)
1013{
1014        int nid = zone_to_nid(zone);
1015        int zid = zone_idx(zone);
1016        struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
1017
1018        return &mz->reclaim_stat;
1019}
1020
1021struct zone_reclaim_stat *
1022mem_cgroup_get_reclaim_stat_from_page(struct page *page)
1023{
1024        struct page_cgroup *pc;
1025        struct mem_cgroup_per_zone *mz;
1026
1027        if (mem_cgroup_disabled())
1028                return NULL;
1029
1030        pc = lookup_page_cgroup(page);
1031        if (!PageCgroupUsed(pc))
1032                return NULL;
1033        /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
1034        smp_rmb();
1035        mz = page_cgroup_zoneinfo(pc);
1036        if (!mz)
1037                return NULL;
1038
1039        return &mz->reclaim_stat;
1040}
1041
1042unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
1043                                        struct list_head *dst,
1044                                        unsigned long *scanned, int order,
1045                                        int mode, struct zone *z,
1046                                        struct mem_cgroup *mem_cont,
1047                                        int active, int file)
1048{
1049        unsigned long nr_taken = 0;
1050        struct page *page;
1051        unsigned long scan;
1052        LIST_HEAD(pc_list);
1053        struct list_head *src;
1054        struct page_cgroup *pc, *tmp;
1055        int nid = zone_to_nid(z);
1056        int zid = zone_idx(z);
1057        struct mem_cgroup_per_zone *mz;
1058        int lru = LRU_FILE * file + active;
1059        int ret;
1060
1061        BUG_ON(!mem_cont);
1062        mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
1063        src = &mz->lists[lru];
1064
1065        scan = 0;
1066        list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
1067                if (scan >= nr_to_scan)
1068                        break;
1069
1070                page = pc->page;
1071                if (unlikely(!PageCgroupUsed(pc)))
1072                        continue;
1073                if (unlikely(!PageLRU(page)))
1074                        continue;
1075
1076                scan++;
1077                ret = __isolate_lru_page(page, mode, file);
1078                switch (ret) {
1079                case 0:
1080                        list_move(&page->lru, dst);
1081                        mem_cgroup_del_lru(page);
1082                        nr_taken += hpage_nr_pages(page);
1083                        break;
1084                case -EBUSY:
1085                        /* we don't affect global LRU but rotate in our LRU */
1086                        mem_cgroup_rotate_lru_list(page, page_lru(page));
1087                        break;
1088                default:
1089                        break;
1090                }
1091        }
1092
1093        *scanned = scan;
1094
1095        trace_mm_vmscan_memcg_isolate(0, nr_to_scan, scan, nr_taken,
1096                                      0, 0, 0, mode);
1097
1098        return nr_taken;
1099}
1100
1101#define mem_cgroup_from_res_counter(counter, member)    \
1102        container_of(counter, struct mem_cgroup, member)
1103
1104static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
1105{
1106        if (do_swap_account) {
1107                if (res_counter_check_under_limit(&mem->res) &&
1108                        res_counter_check_under_limit(&mem->memsw))
1109                        return true;
1110        } else
1111                if (res_counter_check_under_limit(&mem->res))
1112                        return true;
1113        return false;
1114}
1115
1116/**
1117 * mem_cgroup_check_margin - check if the memory cgroup allows charging
1118 * @mem: memory cgroup to check
1119 * @bytes: the number of bytes the caller intends to charge
1120 *
1121 * Returns a boolean value on whether @mem can be charged @bytes or
1122 * whether this would exceed the limit.
1123 */
1124static bool mem_cgroup_check_margin(struct mem_cgroup *mem, unsigned long bytes)
1125{
1126        if (!res_counter_check_margin(&mem->res, bytes))
1127                return false;
1128        if (do_swap_account && !res_counter_check_margin(&mem->memsw, bytes))
1129                return false;
1130        return true;
1131}
1132
1133static unsigned int get_swappiness(struct mem_cgroup *memcg)
1134{
1135        struct cgroup *cgrp = memcg->css.cgroup;
1136        unsigned int swappiness;
1137
1138        /* root ? */
1139        if (cgrp->parent == NULL)
1140                return vm_swappiness;
1141
1142        spin_lock(&memcg->reclaim_param_lock);
1143        swappiness = memcg->swappiness;
1144        spin_unlock(&memcg->reclaim_param_lock);
1145
1146        return swappiness;
1147}
1148
1149static void mem_cgroup_start_move(struct mem_cgroup *mem)
1150{
1151        int cpu;
1152
1153        get_online_cpus();
1154        spin_lock(&mem->pcp_counter_lock);
1155        for_each_online_cpu(cpu)
1156                per_cpu(mem->stat->count[MEM_CGROUP_ON_MOVE], cpu) += 1;
1157        mem->nocpu_base.count[MEM_CGROUP_ON_MOVE] += 1;
1158        spin_unlock(&mem->pcp_counter_lock);
1159        put_online_cpus();
1160
1161        synchronize_rcu();
1162}
1163
1164static void mem_cgroup_end_move(struct mem_cgroup *mem)
1165{
1166        int cpu;
1167
1168        if (!mem)
1169                return;
1170        get_online_cpus();
1171        spin_lock(&mem->pcp_counter_lock);
1172        for_each_online_cpu(cpu)
1173                per_cpu(mem->stat->count[MEM_CGROUP_ON_MOVE], cpu) -= 1;
1174        mem->nocpu_base.count[MEM_CGROUP_ON_MOVE] -= 1;
1175        spin_unlock(&mem->pcp_counter_lock);
1176        put_online_cpus();
1177}
1178/*
1179 * 2 routines for checking "mem" is under move_account() or not.
1180 *
1181 * mem_cgroup_stealed() - checking a cgroup is mc.from or not. This is used
1182 *                        for avoiding race in accounting. If true,
1183 *                        pc->mem_cgroup may be overwritten.
1184 *
1185 * mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
1186 *                        under hierarchy of moving cgroups. This is for
1187 *                        waiting at hith-memory prressure caused by "move".
1188 */
1189
1190static bool mem_cgroup_stealed(struct mem_cgroup *mem)
1191{
1192        VM_BUG_ON(!rcu_read_lock_held());
1193        return this_cpu_read(mem->stat->count[MEM_CGROUP_ON_MOVE]) > 0;
1194}
1195
1196static bool mem_cgroup_under_move(struct mem_cgroup *mem)
1197{
1198        struct mem_cgroup *from;
1199        struct mem_cgroup *to;
1200        bool ret = false;
1201        /*
1202         * Unlike task_move routines, we access mc.to, mc.from not under
1203         * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
1204         */
1205        spin_lock(&mc.lock);
1206        from = mc.from;
1207        to = mc.to;
1208        if (!from)
1209                goto unlock;
1210        if (from == mem || to == mem
1211            || (mem->use_hierarchy && css_is_ancestor(&from->css, &mem->css))
1212            || (mem->use_hierarchy && css_is_ancestor(&to->css, &mem->css)))
1213                ret = true;
1214unlock:
1215        spin_unlock(&mc.lock);
1216        return ret;
1217}
1218
1219static bool mem_cgroup_wait_acct_move(struct mem_cgroup *mem)
1220{
1221        if (mc.moving_task && current != mc.moving_task) {
1222                if (mem_cgroup_under_move(mem)) {
1223                        DEFINE_WAIT(wait);
1224                        prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
1225                        /* moving charge context might have finished. */
1226                        if (mc.moving_task)
1227                                schedule();
1228                        finish_wait(&mc.waitq, &wait);
1229                        return true;
1230                }
1231        }
1232        return false;
1233}
1234
1235/**
1236 * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
1237 * @memcg: The memory cgroup that went over limit
1238 * @p: Task that is going to be killed
1239 *
1240 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1241 * enabled
1242 */
1243void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
1244{
1245        struct cgroup *task_cgrp;
1246        struct cgroup *mem_cgrp;
1247        /*
1248         * Need a buffer in BSS, can't rely on allocations. The code relies
1249         * on the assumption that OOM is serialized for memory controller.
1250         * If this assumption is broken, revisit this code.
1251         */
1252        static char memcg_name[PATH_MAX];
1253        int ret;
1254
1255        if (!memcg || !p)
1256                return;
1257
1258
1259        rcu_read_lock();
1260
1261        mem_cgrp = memcg->css.cgroup;
1262        task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
1263
1264        ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
1265        if (ret < 0) {
1266                /*
1267                 * Unfortunately, we are unable to convert to a useful name
1268                 * But we'll still print out the usage information
1269                 */
1270                rcu_read_unlock();
1271                goto done;
1272        }
1273        rcu_read_unlock();
1274
1275        printk(KERN_INFO "Task in %s killed", memcg_name);
1276
1277        rcu_read_lock();
1278        ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
1279        if (ret < 0) {
1280                rcu_read_unlock();
1281                goto done;
1282        }
1283        rcu_read_unlock();
1284
1285        /*
1286         * Continues from above, so we don't need an KERN_ level
1287         */
1288        printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
1289done:
1290
1291        printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
1292                res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
1293                res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
1294                res_counter_read_u64(&memcg->res, RES_FAILCNT));
1295        printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
1296                "failcnt %llu\n",
1297                res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
1298                res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
1299                res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1300}
1301
1302/*
1303 * This function returns the number of memcg under hierarchy tree. Returns
1304 * 1(self count) if no children.
1305 */
1306static int mem_cgroup_count_children(struct mem_cgroup *mem)
1307{
1308        int num = 0;
1309        struct mem_cgroup *iter;
1310
1311        for_each_mem_cgroup_tree(iter, mem)
1312                num++;
1313        return num;
1314}
1315
1316/*
1317 * Return the memory (and swap, if configured) limit for a memcg.
1318 */
1319u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
1320{
1321        u64 limit;
1322        u64 memsw;
1323
1324        limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
1325        limit += total_swap_pages << PAGE_SHIFT;
1326
1327        memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1328        /*
1329         * If memsw is finite and limits the amount of swap space available
1330         * to this memcg, return that limit.
1331         */
1332        return min(limit, memsw);
1333}
1334
1335/*
1336 * Visit the first child (need not be the first child as per the ordering
1337 * of the cgroup list, since we track last_scanned_child) of @mem and use
1338 * that to reclaim free pages from.
1339 */
1340static struct mem_cgroup *
1341mem_cgroup_select_victim(struct mem_cgroup *root_mem)
1342{
1343        struct mem_cgroup *ret = NULL;
1344        struct cgroup_subsys_state *css;
1345        int nextid, found;
1346
1347        if (!root_mem->use_hierarchy) {
1348                css_get(&root_mem->css);
1349                ret = root_mem;
1350        }
1351
1352        while (!ret) {
1353                rcu_read_lock();
1354                nextid = root_mem->last_scanned_child + 1;
1355                css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css,
1356                                   &found);
1357                if (css && css_tryget(css))
1358                        ret = container_of(css, struct mem_cgroup, css);
1359
1360                rcu_read_unlock();
1361                /* Updates scanning parameter */
1362                spin_lock(&root_mem->reclaim_param_lock);
1363                if (!css) {
1364                        /* this means start scan from ID:1 */
1365                        root_mem->last_scanned_child = 0;
1366                } else
1367                        root_mem->last_scanned_child = found;
1368                spin_unlock(&root_mem->reclaim_param_lock);
1369        }
1370
1371        return ret;
1372}
1373
1374/*
1375 * Scan the hierarchy if needed to reclaim memory. We remember the last child
1376 * we reclaimed from, so that we don't end up penalizing one child extensively
1377 * based on its position in the children list.
1378 *
1379 * root_mem is the original ancestor that we've been reclaim from.
1380 *
1381 * We give up and return to the caller when we visit root_mem twice.
1382 * (other groups can be removed while we're walking....)
1383 *
1384 * If shrink==true, for avoiding to free too much, this returns immedieately.
1385 */
1386static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
1387                                                struct zone *zone,
1388                                                gfp_t gfp_mask,
1389                                                unsigned long reclaim_options)
1390{
1391        struct mem_cgroup *victim;
1392        int ret, total = 0;
1393        int loop = 0;
1394        bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
1395        bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
1396        bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
1397        unsigned long excess = mem_cgroup_get_excess(root_mem);
1398
1399        /* If memsw_is_minimum==1, swap-out is of-no-use. */
1400        if (root_mem->memsw_is_minimum)
1401                noswap = true;
1402
1403        while (1) {
1404                victim = mem_cgroup_select_victim(root_mem);
1405                if (victim == root_mem) {
1406                        loop++;
1407                        if (loop >= 1)
1408                                drain_all_stock_async();
1409                        if (loop >= 2) {
1410                                /*
1411                                 * If we have not been able to reclaim
1412                                 * anything, it might because there are
1413                                 * no reclaimable pages under this hierarchy
1414                                 */
1415                                if (!check_soft || !total) {
1416                                        css_put(&victim->css);
1417                                        break;
1418                                }
1419                                /*
1420                                 * We want to do more targetted reclaim.
1421                                 * excess >> 2 is not to excessive so as to
1422                                 * reclaim too much, nor too less that we keep
1423                                 * coming back to reclaim from this cgroup
1424                                 */
1425                                if (total >= (excess >> 2) ||
1426                                        (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) {
1427                                        css_put(&victim->css);
1428                                        break;
1429                                }
1430                        }
1431                }
1432                if (!mem_cgroup_local_usage(victim)) {
1433                        /* this cgroup's local usage == 0 */
1434                        css_put(&victim->css);
1435                        continue;
1436                }
1437                /* we use swappiness of local cgroup */
1438                if (check_soft)
1439                        ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
1440                                noswap, get_swappiness(victim), zone);
1441                else
1442                        ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
1443                                                noswap, get_swappiness(victim));
1444                css_put(&victim->css);
1445                /*
1446                 * At shrinking usage, we can't check we should stop here or
1447                 * reclaim more. It's depends on callers. last_scanned_child
1448                 * will work enough for keeping fairness under tree.
1449                 */
1450                if (shrink)
1451                        return ret;
1452                total += ret;
1453                if (check_soft) {
1454                        if (res_counter_check_under_soft_limit(&root_mem->res))
1455                                return total;
1456                } else if (mem_cgroup_check_under_limit(root_mem))
1457                        return 1 + total;
1458        }
1459        return total;
1460}
1461
1462/*
1463 * Check OOM-Killer is already running under our hierarchy.
1464 * If someone is running, return false.
1465 */
1466static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
1467{
1468        int x, lock_count = 0;
1469        struct mem_cgroup *iter;
1470
1471        for_each_mem_cgroup_tree(iter, mem) {
1472                x = atomic_inc_return(&iter->oom_lock);
1473                lock_count = max(x, lock_count);
1474        }
1475
1476        if (lock_count == 1)
1477                return true;
1478        return false;
1479}
1480
1481static int mem_cgroup_oom_unlock(struct mem_cgroup *mem)
1482{
1483        struct mem_cgroup *iter;
1484
1485        /*
1486         * When a new child is created while the hierarchy is under oom,
1487         * mem_cgroup_oom_lock() may not be called. We have to use
1488         * atomic_add_unless() here.
1489         */
1490        for_each_mem_cgroup_tree(iter, mem)
1491                atomic_add_unless(&iter->oom_lock, -1, 0);
1492        return 0;
1493}
1494
1495
1496static DEFINE_MUTEX(memcg_oom_mutex);
1497static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1498
1499struct oom_wait_info {
1500        struct mem_cgroup *mem;
1501        wait_queue_t    wait;
1502};
1503
1504static int memcg_oom_wake_function(wait_queue_t *wait,
1505        unsigned mode, int sync, void *arg)
1506{
1507        struct mem_cgroup *wake_mem = (struct mem_cgroup *)arg;
1508        struct oom_wait_info *oom_wait_info;
1509
1510        oom_wait_info = container_of(wait, struct oom_wait_info, wait);
1511
1512        if (oom_wait_info->mem == wake_mem)
1513                goto wakeup;
1514        /* if no hierarchy, no match */
1515        if (!oom_wait_info->mem->use_hierarchy || !wake_mem->use_hierarchy)
1516                return 0;
1517        /*
1518         * Both of oom_wait_info->mem and wake_mem are stable under us.
1519         * Then we can use css_is_ancestor without taking care of RCU.
1520         */
1521        if (!css_is_ancestor(&oom_wait_info->mem->css, &wake_mem->css) &&
1522            !css_is_ancestor(&wake_mem->css, &oom_wait_info->mem->css))
1523                return 0;
1524
1525wakeup:
1526        return autoremove_wake_function(wait, mode, sync, arg);
1527}
1528
1529static void memcg_wakeup_oom(struct mem_cgroup *mem)
1530{
1531        /* for filtering, pass "mem" as argument. */
1532        __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, mem);
1533}
1534
1535static void memcg_oom_recover(struct mem_cgroup *mem)
1536{
1537        if (mem && atomic_read(&mem->oom_lock))
1538                memcg_wakeup_oom(mem);
1539}
1540
1541/*
1542 * try to call OOM killer. returns false if we should exit memory-reclaim loop.
1543 */
1544bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
1545{
1546        struct oom_wait_info owait;
1547        bool locked, need_to_kill;
1548
1549        owait.mem = mem;
1550        owait.wait.flags = 0;
1551        owait.wait.func = memcg_oom_wake_function;
1552        owait.wait.private = current;
1553        INIT_LIST_HEAD(&owait.wait.task_list);
1554        need_to_kill = true;
1555        /* At first, try to OOM lock hierarchy under mem.*/
1556        mutex_lock(&memcg_oom_mutex);
1557        locked = mem_cgroup_oom_lock(mem);
1558        /*
1559         * Even if signal_pending(), we can't quit charge() loop without
1560         * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
1561         * under OOM is always welcomed, use TASK_KILLABLE here.
1562         */
1563        prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
1564        if (!locked || mem->oom_kill_disable)
1565                need_to_kill = false;
1566        if (locked)
1567                mem_cgroup_oom_notify(mem);
1568        mutex_unlock(&memcg_oom_mutex);
1569
1570        if (need_to_kill) {
1571                finish_wait(&memcg_oom_waitq, &owait.wait);
1572                mem_cgroup_out_of_memory(mem, mask);
1573        } else {
1574                schedule();
1575                finish_wait(&memcg_oom_waitq, &owait.wait);
1576        }
1577        mutex_lock(&memcg_oom_mutex);
1578        mem_cgroup_oom_unlock(mem);
1579        memcg_wakeup_oom(mem);
1580        mutex_unlock(&memcg_oom_mutex);
1581
1582        if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
1583                return false;
1584        /* Give chance to dying process */
1585        schedule_timeout(1);
1586        return true;
1587}
1588
1589/*
1590 * Currently used to update mapped file statistics, but the routine can be
1591 * generalized to update other statistics as well.
1592 *
1593 * Notes: Race condition
1594 *
1595 * We usually use page_cgroup_lock() for accessing page_cgroup member but
1596 * it tends to be costly. But considering some conditions, we doesn't need
1597 * to do so _always_.
1598 *
1599 * Considering "charge", lock_page_cgroup() is not required because all
1600 * file-stat operations happen after a page is attached to radix-tree. There
1601 * are no race with "charge".
1602 *
1603 * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
1604 * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
1605 * if there are race with "uncharge". Statistics itself is properly handled
1606 * by flags.
1607 *
1608 * Considering "move", this is an only case we see a race. To make the race
1609 * small, we check MEM_CGROUP_ON_MOVE percpu value and detect there are
1610 * possibility of race condition. If there is, we take a lock.
1611 */
1612
1613void mem_cgroup_update_page_stat(struct page *page,
1614                                 enum mem_cgroup_page_stat_item idx, int val)
1615{
1616        struct mem_cgroup *mem;
1617        struct page_cgroup *pc = lookup_page_cgroup(page);
1618        bool need_unlock = false;
1619        unsigned long uninitialized_var(flags);
1620
1621        if (unlikely(!pc))
1622                return;
1623
1624        rcu_read_lock();
1625        mem = pc->mem_cgroup;
1626        if (unlikely(!mem || !PageCgroupUsed(pc)))
1627                goto out;
1628        /* pc->mem_cgroup is unstable ? */
1629        if (unlikely(mem_cgroup_stealed(mem)) || PageTransHuge(page)) {
1630                /* take a lock against to access pc->mem_cgroup */
1631                move_lock_page_cgroup(pc, &flags);
1632                need_unlock = true;
1633                mem = pc->mem_cgroup;
1634                if (!mem || !PageCgroupUsed(pc))
1635                        goto out;
1636        }
1637
1638        switch (idx) {
1639        case MEMCG_NR_FILE_MAPPED:
1640                if (val > 0)
1641                        SetPageCgroupFileMapped(pc);
1642                else if (!page_mapped(page))
1643                        ClearPageCgroupFileMapped(pc);
1644                idx = MEM_CGROUP_STAT_FILE_MAPPED;
1645                break;
1646        default:
1647                BUG();
1648        }
1649
1650        this_cpu_add(mem->stat->count[idx], val);
1651
1652out:
1653        if (unlikely(need_unlock))
1654                move_unlock_page_cgroup(pc, &flags);
1655        rcu_read_unlock();
1656        return;
1657}
1658EXPORT_SYMBOL(mem_cgroup_update_page_stat);
1659
1660/*
1661 * size of first charge trial. "32" comes from vmscan.c's magic value.
1662 * TODO: maybe necessary to use big numbers in big irons.
1663 */
1664#define CHARGE_SIZE     (32 * PAGE_SIZE)
1665struct memcg_stock_pcp {
1666        struct mem_cgroup *cached; /* this never be root cgroup */
1667        int charge;
1668        struct work_struct work;
1669};
1670static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
1671static atomic_t memcg_drain_count;
1672
1673/*
1674 * Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed
1675 * from local stock and true is returned. If the stock is 0 or charges from a
1676 * cgroup which is not current target, returns false. This stock will be
1677 * refilled.
1678 */
1679static bool consume_stock(struct mem_cgroup *mem)
1680{
1681        struct memcg_stock_pcp *stock;
1682        bool ret = true;
1683
1684        stock = &get_cpu_var(memcg_stock);
1685        if (mem == stock->cached && stock->charge)
1686                stock->charge -= PAGE_SIZE;
1687        else /* need to call res_counter_charge */
1688                ret = false;
1689        put_cpu_var(memcg_stock);
1690        return ret;
1691}
1692
1693/*
1694 * Returns stocks cached in percpu to res_counter and reset cached information.
1695 */
1696static void drain_stock(struct memcg_stock_pcp *stock)
1697{
1698        struct mem_cgroup *old = stock->cached;
1699
1700        if (stock->charge) {
1701                res_counter_uncharge(&old->res, stock->charge);
1702                if (do_swap_account)
1703                        res_counter_uncharge(&old->memsw, stock->charge);
1704        }
1705        stock->cached = NULL;
1706        stock->charge = 0;
1707}
1708
1709/*
1710 * This must be called under preempt disabled or must be called by
1711 * a thread which is pinned to local cpu.
1712 */
1713static void drain_local_stock(struct work_struct *dummy)
1714{
1715        struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
1716        drain_stock(stock);
1717}
1718
1719/*
1720 * Cache charges(val) which is from res_counter, to local per_cpu area.
1721 * This will be consumed by consume_stock() function, later.
1722 */
1723static void refill_stock(struct mem_cgroup *mem, int val)
1724{
1725        struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
1726
1727        if (stock->cached != mem) { /* reset if necessary */
1728                drain_stock(stock);
1729                stock->cached = mem;
1730        }
1731        stock->charge += val;
1732        put_cpu_var(memcg_stock);
1733}
1734
1735/*
1736 * Tries to drain stocked charges in other cpus. This function is asynchronous
1737 * and just put a work per cpu for draining localy on each cpu. Caller can
1738 * expects some charges will be back to res_counter later but cannot wait for
1739 * it.
1740 */
1741static void drain_all_stock_async(void)
1742{
1743        int cpu;
1744        /* This function is for scheduling "drain" in asynchronous way.
1745         * The result of "drain" is not directly handled by callers. Then,
1746         * if someone is calling drain, we don't have to call drain more.
1747         * Anyway, WORK_STRUCT_PENDING check in queue_work_on() will catch if
1748         * there is a race. We just do loose check here.
1749         */
1750        if (atomic_read(&memcg_drain_count))
1751                return;
1752        /* Notify other cpus that system-wide "drain" is running */
1753        atomic_inc(&memcg_drain_count);
1754        get_online_cpus();
1755        for_each_online_cpu(cpu) {
1756                struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
1757                schedule_work_on(cpu, &stock->work);
1758        }
1759        put_online_cpus();
1760        atomic_dec(&memcg_drain_count);
1761        /* We don't wait for flush_work */
1762}
1763
1764/* This is a synchronous drain interface. */
1765static void drain_all_stock_sync(void)
1766{
1767        /* called when force_empty is called */
1768        atomic_inc(&memcg_drain_count);
1769        schedule_on_each_cpu(drain_local_stock);
1770        atomic_dec(&memcg_drain_count);
1771}
1772
1773/*
1774 * This function drains percpu counter value from DEAD cpu and
1775 * move it to local cpu. Note that this function can be preempted.
1776 */
1777static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *mem, int cpu)
1778{
1779        int i;
1780
1781        spin_lock(&mem->pcp_counter_lock);
1782        for (i = 0; i < MEM_CGROUP_STAT_DATA; i++) {
1783                s64 x = per_cpu(mem->stat->count[i], cpu);
1784
1785                per_cpu(mem->stat->count[i], cpu) = 0;
1786                mem->nocpu_base.count[i] += x;
1787        }
1788        /* need to clear ON_MOVE value, works as a kind of lock. */
1789        per_cpu(mem->stat->count[MEM_CGROUP_ON_MOVE], cpu) = 0;
1790        spin_unlock(&mem->pcp_counter_lock);
1791}
1792
1793static void synchronize_mem_cgroup_on_move(struct mem_cgroup *mem, int cpu)
1794{
1795        int idx = MEM_CGROUP_ON_MOVE;
1796
1797        spin_lock(&mem->pcp_counter_lock);
1798        per_cpu(mem->stat->count[idx], cpu) = mem->nocpu_base.count[idx];
1799        spin_unlock(&mem->pcp_counter_lock);
1800}
1801
1802static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb,
1803                                        unsigned long action,
1804                                        void *hcpu)
1805{
1806        int cpu = (unsigned long)hcpu;
1807        struct memcg_stock_pcp *stock;
1808        struct mem_cgroup *iter;
1809
1810        if ((action == CPU_ONLINE)) {
1811                for_each_mem_cgroup_all(iter)
1812                        synchronize_mem_cgroup_on_move(iter, cpu);
1813                return NOTIFY_OK;
1814        }
1815
1816        if ((action != CPU_DEAD) || action != CPU_DEAD_FROZEN)
1817                return NOTIFY_OK;
1818
1819        for_each_mem_cgroup_all(iter)
1820                mem_cgroup_drain_pcp_counter(iter, cpu);
1821
1822        stock = &per_cpu(memcg_stock, cpu);
1823        drain_stock(stock);
1824        return NOTIFY_OK;
1825}
1826
1827
1828/* See __mem_cgroup_try_charge() for details */
1829enum {
1830        CHARGE_OK,              /* success */
1831        CHARGE_RETRY,           /* need to retry but retry is not bad */
1832        CHARGE_NOMEM,           /* we can't do more. return -ENOMEM */
1833        CHARGE_WOULDBLOCK,      /* GFP_WAIT wasn't set and no enough res. */
1834        CHARGE_OOM_DIE,         /* the current is killed because of OOM */
1835};
1836
1837static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
1838                                int csize, bool oom_check)
1839{
1840        struct mem_cgroup *mem_over_limit;
1841        struct res_counter *fail_res;
1842        unsigned long flags = 0;
1843        int ret;
1844
1845        ret = res_counter_charge(&mem->res, csize, &fail_res);
1846
1847        if (likely(!ret)) {
1848                if (!do_swap_account)
1849                        return CHARGE_OK;
1850                ret = res_counter_charge(&mem->memsw, csize, &fail_res);
1851                if (likely(!ret))
1852                        return CHARGE_OK;
1853
1854                res_counter_uncharge(&mem->res, csize);
1855                mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
1856                flags |= MEM_CGROUP_RECLAIM_NOSWAP;
1857        } else
1858                mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
1859        /*
1860         * csize can be either a huge page (HPAGE_SIZE), a batch of
1861         * regular pages (CHARGE_SIZE), or a single regular page
1862         * (PAGE_SIZE).
1863         *
1864         * Never reclaim on behalf of optional batching, retry with a
1865         * single page instead.
1866         */
1867        if (csize == CHARGE_SIZE)
1868                return CHARGE_RETRY;
1869
1870        if (!(gfp_mask & __GFP_WAIT))
1871                return CHARGE_WOULDBLOCK;
1872
1873        ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
1874                                              gfp_mask, flags);
1875        if (mem_cgroup_check_margin(mem_over_limit, csize))
1876                return CHARGE_RETRY;
1877        /*
1878         * Even though the limit is exceeded at this point, reclaim
1879         * may have been able to free some pages.  Retry the charge
1880         * before killing the task.
1881         *
1882         * Only for regular pages, though: huge pages are rather
1883         * unlikely to succeed so close to the limit, and we fall back
1884         * to regular pages anyway in case of failure.
1885         */
1886        if (csize == PAGE_SIZE && ret)
1887                return CHARGE_RETRY;
1888
1889        /*
1890         * At task move, charge accounts can be doubly counted. So, it's
1891         * better to wait until the end of task_move if something is going on.
1892         */
1893        if (mem_cgroup_wait_acct_move(mem_over_limit))
1894                return CHARGE_RETRY;
1895
1896        /* If we don't need to call oom-killer at el, return immediately */
1897        if (!oom_check)
1898                return CHARGE_NOMEM;
1899        /* check OOM */
1900        if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask))
1901                return CHARGE_OOM_DIE;
1902
1903        return CHARGE_RETRY;
1904}
1905
1906/*
1907 * Unlike exported interface, "oom" parameter is added. if oom==true,
1908 * oom-killer can be invoked.
1909 */
1910static int __mem_cgroup_try_charge(struct mm_struct *mm,
1911                                   gfp_t gfp_mask,
1912                                   struct mem_cgroup **memcg, bool oom,
1913                                   int page_size)
1914{
1915        int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
1916        struct mem_cgroup *mem = NULL;
1917        int ret;
1918        int csize = max(CHARGE_SIZE, (unsigned long) page_size);
1919
1920        /*
1921         * Unlike gloval-vm's OOM-kill, we're not in memory shortage
1922         * in system level. So, allow to go ahead dying process in addition to
1923         * MEMDIE process.
1924         */
1925        if (unlikely(test_thread_flag(TIF_MEMDIE)
1926                     || fatal_signal_pending(current)))
1927                goto bypass;
1928
1929        /*
1930         * We always charge the cgroup the mm_struct belongs to.
1931         * The mm_struct's mem_cgroup changes on task migration if the
1932         * thread group leader migrates. It's possible that mm is not
1933         * set, if so charge the init_mm (happens for pagecache usage).
1934         */
1935        if (!*memcg && !mm)
1936                goto bypass;
1937again:
1938        if (*memcg) { /* css should be a valid one */
1939                mem = *memcg;
1940                VM_BUG_ON(css_is_removed(&mem->css));
1941                if (mem_cgroup_is_root(mem))
1942                        goto done;
1943                if (page_size == PAGE_SIZE && consume_stock(mem))
1944                        goto done;
1945                css_get(&mem->css);
1946        } else {
1947                struct task_struct *p;
1948
1949                rcu_read_lock();
1950                p = rcu_dereference(mm->owner);
1951                /*
1952                 * Because we don't have task_lock(), "p" can exit.
1953                 * In that case, "mem" can point to root or p can be NULL with
1954                 * race with swapoff. Then, we have small risk of mis-accouning.
1955                 * But such kind of mis-account by race always happens because
1956                 * we don't have cgroup_mutex(). It's overkill and we allo that
1957                 * small race, here.
1958                 * (*) swapoff at el will charge against mm-struct not against
1959                 * task-struct. So, mm->owner can be NULL.
1960                 */
1961                mem = mem_cgroup_from_task(p);
1962                if (!mem || mem_cgroup_is_root(mem)) {
1963                        rcu_read_unlock();
1964                        goto done;
1965                }
1966                if (page_size == PAGE_SIZE && consume_stock(mem)) {
1967                        /*
1968                         * It seems dagerous to access memcg without css_get().
1969                         * But considering how consume_stok works, it's not
1970                         * necessary. If consume_stock success, some charges
1971                         * from this memcg are cached on this cpu. So, we
1972                         * don't need to call css_get()/css_tryget() before
1973                         * calling consume_stock().
1974                         */
1975                        rcu_read_unlock();
1976                        goto done;
1977                }
1978                /* after here, we may be blocked. we need to get refcnt */
1979                if (!css_tryget(&mem->css)) {
1980                        rcu_read_unlock();
1981                        goto again;
1982                }
1983                rcu_read_unlock();
1984        }
1985
1986        do {
1987                bool oom_check;
1988
1989                /* If killed, bypass charge */
1990                if (fatal_signal_pending(current)) {
1991                        css_put(&mem->css);
1992                        goto bypass;
1993                }
1994
1995                oom_check = false;
1996                if (oom && !nr_oom_retries) {
1997                        oom_check = true;
1998                        nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
1999                }
2000
2001                ret = __mem_cgroup_do_charge(mem, gfp_mask, csize, oom_check);
2002
2003                switch (ret) {
2004                case CHARGE_OK:
2005                        break;
2006                case CHARGE_RETRY: /* not in OOM situation but retry */
2007                        csize = page_size;
2008                        css_put(&mem->css);
2009                        mem = NULL;
2010                        goto again;
2011                case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
2012                        css_put(&mem->css);
2013                        goto nomem;
2014                case CHARGE_NOMEM: /* OOM routine works */
2015                        if (!oom) {
2016                                css_put(&mem->css);
2017                                goto nomem;
2018                        }
2019                        /* If oom, we never return -ENOMEM */
2020                        nr_oom_retries--;
2021                        break;
2022                case CHARGE_OOM_DIE: /* Killed by OOM Killer */
2023                        css_put(&mem->css);
2024                        goto bypass;
2025                }
2026        } while (ret != CHARGE_OK);
2027
2028        if (csize > page_size)
2029                refill_stock(mem, csize - page_size);
2030        css_put(&mem->css);
2031done:
2032        *memcg = mem;
2033        return 0;
2034nomem:
2035        *memcg = NULL;
2036        return -ENOMEM;
2037bypass:
2038        *memcg = NULL;
2039        return 0;
2040}
2041
2042/*
2043 * Somemtimes we have to undo a charge we got by try_charge().
2044 * This function is for that and do uncharge, put css's refcnt.
2045 * gotten by try_charge().
2046 */
2047static void __mem_cgroup_cancel_charge(struct mem_cgroup *mem,
2048                                                        unsigned long count)
2049{
2050        if (!mem_cgroup_is_root(mem)) {
2051                res_counter_uncharge(&mem->res, PAGE_SIZE * count);
2052                if (do_swap_account)
2053                        res_counter_uncharge(&mem->memsw, PAGE_SIZE * count);
2054        }
2055}
2056
2057static void mem_cgroup_cancel_charge(struct mem_cgroup *mem,
2058                                     int page_size)
2059{
2060        __mem_cgroup_cancel_charge(mem, page_size >> PAGE_SHIFT);
2061}
2062
2063/*
2064 * A helper function to get mem_cgroup from ID. must be called under
2065 * rcu_read_lock(). The caller must check css_is_removed() or some if
2066 * it's concern. (dropping refcnt from swap can be called against removed
2067 * memcg.)
2068 */
2069static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
2070{
2071        struct cgroup_subsys_state *css;
2072
2073        /* ID 0 is unused ID */
2074        if (!id)
2075                return NULL;
2076        css = css_lookup(&mem_cgroup_subsys, id);
2077        if (!css)
2078                return NULL;
2079        return container_of(css, struct mem_cgroup, css);
2080}
2081
2082struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
2083{
2084        struct mem_cgroup *mem = NULL;
2085        struct page_cgroup *pc;
2086        unsigned short id;
2087        swp_entry_t ent;
2088
2089        VM_BUG_ON(!PageLocked(page));
2090
2091        pc = lookup_page_cgroup(page);
2092        lock_page_cgroup(pc);
2093        if (PageCgroupUsed(pc)) {
2094                mem = pc->mem_cgroup;
2095                if (mem && !css_tryget(&mem->css))
2096                        mem = NULL;
2097        } else if (PageSwapCache(page)) {
2098                ent.val = page_private(page);
2099                id = lookup_swap_cgroup(ent);
2100                rcu_read_lock();
2101                mem = mem_cgroup_lookup(id);
2102                if (mem && !css_tryget(&mem->css))
2103                        mem = NULL;
2104                rcu_read_unlock();
2105        }
2106        unlock_page_cgroup(pc);
2107        return mem;
2108}
2109
2110static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
2111                                       struct page_cgroup *pc,
2112                                       enum charge_type ctype,
2113                                       int page_size)
2114{
2115        int nr_pages = page_size >> PAGE_SHIFT;
2116
2117        /* try_charge() can return NULL to *memcg, taking care of it. */
2118        if (!mem)
2119                return;
2120
2121        lock_page_cgroup(pc);
2122        if (unlikely(PageCgroupUsed(pc))) {
2123                unlock_page_cgroup(pc);
2124                mem_cgroup_cancel_charge(mem, page_size);
2125                return;
2126        }
2127        /*
2128         * we don't need page_cgroup_lock about tail pages, becase they are not
2129         * accessed by any other context at this point.
2130         */
2131        pc->mem_cgroup = mem;
2132        /*
2133         * We access a page_cgroup asynchronously without lock_page_cgroup().
2134         * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
2135         * is accessed after testing USED bit. To make pc->mem_cgroup visible
2136         * before USED bit, we need memory barrier here.
2137         * See mem_cgroup_add_lru_list(), etc.
2138         */
2139        smp_wmb();
2140        switch (ctype) {
2141        case MEM_CGROUP_CHARGE_TYPE_CACHE:
2142        case MEM_CGROUP_CHARGE_TYPE_SHMEM:
2143                SetPageCgroupCache(pc);
2144                SetPageCgroupUsed(pc);
2145                break;
2146        case MEM_CGROUP_CHARGE_TYPE_MAPPED:
2147                ClearPageCgroupCache(pc);
2148                SetPageCgroupUsed(pc);
2149                break;
2150        default:
2151                break;
2152        }
2153
2154        mem_cgroup_charge_statistics(mem, PageCgroupCache(pc), nr_pages);
2155        unlock_page_cgroup(pc);
2156        /*
2157         * "charge_statistics" updated event counter. Then, check it.
2158         * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
2159         * if they exceeds softlimit.
2160         */
2161        memcg_check_events(mem, pc->page);
2162}
2163
2164#ifdef CONFIG_TRANSPARENT_HUGEPAGE
2165
2166#define PCGF_NOCOPY_AT_SPLIT ((1 << PCG_LOCK) | (1 << PCG_MOVE_LOCK) |\
2167                        (1 << PCG_ACCT_LRU) | (1 << PCG_MIGRATION))
2168/*
2169 * Because tail pages are not marked as "used", set it. We're under
2170 * zone->lru_lock, 'splitting on pmd' and compund_lock.
2171 */
2172void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail)
2173{
2174        struct page_cgroup *head_pc = lookup_page_cgroup(head);
2175        struct page_cgroup *tail_pc = lookup_page_cgroup(tail);
2176        unsigned long flags;
2177
2178        if (mem_cgroup_disabled())
2179                return;
2180        /*
2181         * We have no races with charge/uncharge but will have races with
2182         * page state accounting.
2183         */
2184        move_lock_page_cgroup(head_pc, &flags);
2185
2186        tail_pc->mem_cgroup = head_pc->mem_cgroup;
2187        smp_wmb(); /* see __commit_charge() */
2188        if (PageCgroupAcctLRU(head_pc)) {
2189                enum lru_list lru;
2190                struct mem_cgroup_per_zone *mz;
2191
2192                /*
2193                 * LRU flags cannot be copied because we need to add tail
2194                 *.page to LRU by generic call and our hook will be called.
2195                 * We hold lru_lock, then, reduce counter directly.
2196                 */
2197                lru = page_lru(head);
2198                mz = page_cgroup_zoneinfo(head_pc);
2199                MEM_CGROUP_ZSTAT(mz, lru) -= 1;
2200        }
2201        tail_pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
2202        move_unlock_page_cgroup(head_pc, &flags);
2203}
2204#endif
2205
2206/**
2207 * __mem_cgroup_move_account - move account of the page
2208 * @pc: page_cgroup of the page.
2209 * @from: mem_cgroup which the page is moved from.
2210 * @to: mem_cgroup which the page is moved to. @from != @to.
2211 * @uncharge: whether we should call uncharge and css_put against @from.
2212 *
2213 * The caller must confirm following.
2214 * - page is not on LRU (isolate_page() is useful.)
2215 * - the pc is locked, used, and ->mem_cgroup points to @from.
2216 *
2217 * This function doesn't do "charge" nor css_get to new cgroup. It should be
2218 * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
2219 * true, this function does "uncharge" from old cgroup, but it doesn't if
2220 * @uncharge is false, so a caller should do "uncharge".
2221 */
2222
2223static void __mem_cgroup_move_account(struct page_cgroup *pc,
2224        struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge,
2225        int charge_size)
2226{
2227        int nr_pages = charge_size >> PAGE_SHIFT;
2228
2229        VM_BUG_ON(from == to);
2230        VM_BUG_ON(PageLRU(pc->page));
2231        VM_BUG_ON(!page_is_cgroup_locked(pc));
2232        VM_BUG_ON(!PageCgroupUsed(pc));
2233        VM_BUG_ON(pc->mem_cgroup != from);
2234
2235        if (PageCgroupFileMapped(pc)) {
2236                /* Update mapped_file data for mem_cgroup */
2237                preempt_disable();
2238                __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
2239                __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
2240                preempt_enable();
2241        }
2242        mem_cgroup_charge_statistics(from, PageCgroupCache(pc), -nr_pages);
2243        if (uncharge)
2244                /* This is not "cancel", but cancel_charge does all we need. */
2245                mem_cgroup_cancel_charge(from, charge_size);
2246
2247        /* caller should have done css_get */
2248        pc->mem_cgroup = to;
2249        mem_cgroup_charge_statistics(to, PageCgroupCache(pc), nr_pages);
2250        /*
2251         * We charges against "to" which may not have any tasks. Then, "to"
2252         * can be under rmdir(). But in current implementation, caller of
2253         * this function is just force_empty() and move charge, so it's
2254         * garanteed that "to" is never removed. So, we don't check rmdir
2255         * status here.
2256         */
2257}
2258
2259/*
2260 * check whether the @pc is valid for moving account and call
2261 * __mem_cgroup_move_account()
2262 */
2263static int mem_cgroup_move_account(struct page_cgroup *pc,
2264                struct mem_cgroup *from, struct mem_cgroup *to,
2265                bool uncharge, int charge_size)
2266{
2267        int ret = -EINVAL;
2268        unsigned long flags;
2269        /*
2270         * The page is isolated from LRU. So, collapse function
2271         * will not handle this page. But page splitting can happen.
2272         * Do this check under compound_page_lock(). The caller should
2273         * hold it.
2274         */
2275        if ((charge_size > PAGE_SIZE) && !PageTransHuge(pc->page))
2276                return -EBUSY;
2277
2278        lock_page_cgroup(pc);
2279        if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
2280                move_lock_page_cgroup(pc, &flags);
2281                __mem_cgroup_move_account(pc, from, to, uncharge, charge_size);
2282                move_unlock_page_cgroup(pc, &flags);
2283                ret = 0;
2284        }
2285        unlock_page_cgroup(pc);
2286        /*
2287         * check events
2288         */
2289        memcg_check_events(to, pc->page);
2290        memcg_check_events(from, pc->page);
2291        return ret;
2292}
2293
2294/*
2295 * move charges to its parent.
2296 */
2297
2298static int mem_cgroup_move_parent(struct page_cgroup *pc,
2299                                  struct mem_cgroup *child,
2300                                  gfp_t gfp_mask)
2301{
2302        struct page *page = pc->page;
2303        struct cgroup *cg = child->css.cgroup;
2304        struct cgroup *pcg = cg->parent;
2305        struct mem_cgroup *parent;
2306        int page_size = PAGE_SIZE;
2307        unsigned long flags;
2308        int ret;
2309
2310        /* Is ROOT ? */
2311        if (!pcg)
2312                return -EINVAL;
2313
2314        ret = -EBUSY;
2315        if (!get_page_unless_zero(page))
2316                goto out;
2317        if (isolate_lru_page(page))
2318                goto put;
2319
2320        if (PageTransHuge(page))
2321                page_size = HPAGE_SIZE;
2322
2323        parent = mem_cgroup_from_cont(pcg);
2324        ret = __mem_cgroup_try_charge(NULL, gfp_mask,
2325                                &parent, false, page_size);
2326        if (ret || !parent)
2327                goto put_back;
2328
2329        if (page_size > PAGE_SIZE)
2330                flags = compound_lock_irqsave(page);
2331
2332        ret = mem_cgroup_move_account(pc, child, parent, true, page_size);
2333        if (ret)
2334                mem_cgroup_cancel_charge(parent, page_size);
2335
2336        if (page_size > PAGE_SIZE)
2337                compound_unlock_irqrestore(page, flags);
2338put_back:
2339        putback_lru_page(page);
2340put:
2341        put_page(page);
2342out:
2343        return ret;
2344}
2345
2346/*
2347 * Charge the memory controller for page usage.
2348 * Return
2349 * 0 if the charge was successful
2350 * < 0 if the cgroup is over its limit
2351 */
2352static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
2353                                gfp_t gfp_mask, enum charge_type ctype)
2354{
2355        struct mem_cgroup *mem = NULL;
2356        int page_size = PAGE_SIZE;
2357        struct page_cgroup *pc;
2358        bool oom = true;
2359        int ret;
2360
2361        if (PageTransHuge(page)) {
2362                page_size <<= compound_order(page);
2363                VM_BUG_ON(!PageTransHuge(page));
2364                /*
2365                 * Never OOM-kill a process for a huge page.  The
2366                 * fault handler will fall back to regular pages.
2367                 */
2368                oom = false;
2369        }
2370
2371        pc = lookup_page_cgroup(page);
2372        /* can happen at boot */
2373        if (unlikely(!pc))
2374                return 0;
2375        prefetchw(pc);
2376
2377        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, page_size);
2378        if (ret || !mem)
2379                return ret;
2380
2381        __mem_cgroup_commit_charge(mem, pc, ctype, page_size);
2382        return 0;
2383}
2384
2385int mem_cgroup_newpage_charge(struct page *page,
2386                              struct mm_struct *mm, gfp_t gfp_mask)
2387{
2388        if (mem_cgroup_disabled())
2389                return 0;
2390        /*
2391         * If already mapped, we don't have to account.
2392         * If page cache, page->mapping has address_space.
2393         * But page->mapping may have out-of-use anon_vma pointer,
2394         * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
2395         * is NULL.
2396         */
2397        if (page_mapped(page) || (page->mapping && !PageAnon(page)))
2398                return 0;
2399        if (unlikely(!mm))
2400                mm = &init_mm;
2401        return mem_cgroup_charge_common(page, mm, gfp_mask,
2402                                MEM_CGROUP_CHARGE_TYPE_MAPPED);
2403}
2404
2405static void
2406__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2407                                        enum charge_type ctype);
2408
2409int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
2410                                gfp_t gfp_mask)
2411{
2412        int ret;
2413
2414        if (mem_cgroup_disabled())
2415                return 0;
2416        if (PageCompound(page))
2417                return 0;
2418        /*
2419         * Corner case handling. This is called from add_to_page_cache()
2420         * in usual. But some FS (shmem) precharges this page before calling it
2421         * and call add_to_page_cache() with GFP_NOWAIT.
2422         *
2423         * For GFP_NOWAIT case, the page may be pre-charged before calling
2424         * add_to_page_cache(). (See shmem.c) check it here and avoid to call
2425         * charge twice. (It works but has to pay a bit larger cost.)
2426         * And when the page is SwapCache, it should take swap information
2427         * into account. This is under lock_page() now.
2428         */
2429        if (!(gfp_mask & __GFP_WAIT)) {
2430                struct page_cgroup *pc;
2431
2432                pc = lookup_page_cgroup(page);
2433                if (!pc)
2434                        return 0;
2435                lock_page_cgroup(pc);
2436                if (PageCgroupUsed(pc)) {
2437                        unlock_page_cgroup(pc);
2438                        return 0;
2439                }
2440                unlock_page_cgroup(pc);
2441        }
2442
2443        if (unlikely(!mm))
2444                mm = &init_mm;
2445
2446        if (page_is_file_cache(page))
2447                return mem_cgroup_charge_common(page, mm, gfp_mask,
2448                                MEM_CGROUP_CHARGE_TYPE_CACHE);
2449
2450        /* shmem */
2451        if (PageSwapCache(page)) {
2452                struct mem_cgroup *mem = NULL;
2453
2454                ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
2455                if (!ret)
2456                        __mem_cgroup_commit_charge_swapin(page, mem,
2457                                        MEM_CGROUP_CHARGE_TYPE_SHMEM);
2458        } else
2459                ret = mem_cgroup_charge_common(page, mm, gfp_mask,
2460                                        MEM_CGROUP_CHARGE_TYPE_SHMEM);
2461
2462        return ret;
2463}
2464
2465/*
2466 * While swap-in, try_charge -> commit or cancel, the page is locked.
2467 * And when try_charge() successfully returns, one refcnt to memcg without
2468 * struct page_cgroup is acquired. This refcnt will be consumed by
2469 * "commit()" or removed by "cancel()"
2470 */
2471int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
2472                                 struct page *page,
2473                                 gfp_t mask, struct mem_cgroup **ptr)
2474{
2475        struct mem_cgroup *mem;
2476        int ret;
2477
2478        if (mem_cgroup_disabled())
2479                return 0;
2480
2481        if (!do_swap_account)
2482                goto charge_cur_mm;
2483        /*
2484         * A racing thread's fault, or swapoff, may have already updated
2485         * the pte, and even removed page from swap cache: in those cases
2486         * do_swap_page()'s pte_same() test will fail; but there's also a
2487         * KSM case which does need to charge the page.
2488         */
2489        if (!PageSwapCache(page))
2490                goto charge_cur_mm;
2491        mem = try_get_mem_cgroup_from_page(page);
2492        if (!mem)
2493                goto charge_cur_mm;
2494        *ptr = mem;
2495        ret = __mem_cgroup_try_charge(NULL, mask, ptr, true, PAGE_SIZE);
2496        css_put(&mem->css);
2497        return ret;
2498charge_cur_mm:
2499        if (unlikely(!mm))
2500                mm = &init_mm;
2501        return __mem_cgroup_try_charge(mm, mask, ptr, true, PAGE_SIZE);
2502}
2503
2504static void
2505__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2506                                        enum charge_type ctype)
2507{
2508        struct page_cgroup *pc;
2509
2510        if (mem_cgroup_disabled())
2511                return;
2512        if (!ptr)
2513                return;
2514        cgroup_exclude_rmdir(&ptr->css);
2515        pc = lookup_page_cgroup(page);
2516        mem_cgroup_lru_del_before_commit_swapcache(page);
2517        __mem_cgroup_commit_charge(ptr, pc, ctype, PAGE_SIZE);
2518        mem_cgroup_lru_add_after_commit_swapcache(page);
2519        /*
2520         * Now swap is on-memory. This means this page may be
2521         * counted both as mem and swap....double count.
2522         * Fix it by uncharging from memsw. Basically, this SwapCache is stable
2523         * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
2524         * may call delete_from_swap_cache() before reach here.
2525         */
2526        if (do_swap_account && PageSwapCache(page)) {
2527                swp_entry_t ent = {.val = page_private(page)};
2528                unsigned short id;
2529                struct mem_cgroup *memcg;
2530
2531                id = swap_cgroup_record(ent, 0);
2532                rcu_read_lock();
2533                memcg = mem_cgroup_lookup(id);
2534                if (memcg) {
2535                        /*
2536                         * This recorded memcg can be obsolete one. So, avoid
2537                         * calling css_tryget
2538                         */
2539                        if (!mem_cgroup_is_root(memcg))
2540                                res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2541                        mem_cgroup_swap_statistics(memcg, false);
2542                        mem_cgroup_put(memcg);
2543                }
2544                rcu_read_unlock();
2545        }
2546        /*
2547         * At swapin, we may charge account against cgroup which has no tasks.
2548         * So, rmdir()->pre_destroy() can be called while we do this charge.
2549         * In that case, we need to call pre_destroy() again. check it here.
2550         */
2551        cgroup_release_and_wakeup_rmdir(&ptr->css);
2552}
2553
2554void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
2555{
2556        __mem_cgroup_commit_charge_swapin(page, ptr,
2557                                        MEM_CGROUP_CHARGE_TYPE_MAPPED);
2558}
2559
2560void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
2561{
2562        if (mem_cgroup_disabled())
2563                return;
2564        if (!mem)
2565                return;
2566        mem_cgroup_cancel_charge(mem, PAGE_SIZE);
2567}
2568
2569static void
2570__do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype,
2571              int page_size)
2572{
2573        struct memcg_batch_info *batch = NULL;
2574        bool uncharge_memsw = true;
2575        /* If swapout, usage of swap doesn't decrease */
2576        if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2577                uncharge_memsw = false;
2578
2579        batch = &current->memcg_batch;
2580        /*
2581         * In usual, we do css_get() when we remember memcg pointer.
2582         * But in this case, we keep res->usage until end of a series of
2583         * uncharges. Then, it's ok to ignore memcg's refcnt.
2584         */
2585        if (!batch->memcg)
2586                batch->memcg = mem;
2587        /*
2588         * do_batch > 0 when unmapping pages or inode invalidate/truncate.
2589         * In those cases, all pages freed continously can be expected to be in
2590         * the same cgroup and we have chance to coalesce uncharges.
2591         * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
2592         * because we want to do uncharge as soon as possible.
2593         */
2594
2595        if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
2596                goto direct_uncharge;
2597
2598        if (page_size != PAGE_SIZE)
2599                goto direct_uncharge;
2600
2601        /*
2602         * In typical case, batch->memcg == mem. This means we can
2603         * merge a series of uncharges to an uncharge of res_counter.
2604         * If not, we uncharge res_counter ony by one.
2605         */
2606        if (batch->memcg != mem)
2607                goto direct_uncharge;
2608        /* remember freed charge and uncharge it later */
2609        batch->bytes += PAGE_SIZE;
2610        if (uncharge_memsw)
2611                batch->memsw_bytes += PAGE_SIZE;
2612        return;
2613direct_uncharge:
2614        res_counter_uncharge(&mem->res, page_size);
2615        if (uncharge_memsw)
2616                res_counter_uncharge(&mem->memsw, page_size);
2617        if (unlikely(batch->memcg != mem))
2618                memcg_oom_recover(mem);
2619        return;
2620}
2621
2622/*
2623 * uncharge if !page_mapped(page)
2624 */
2625static struct mem_cgroup *
2626__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
2627{
2628        int count;
2629        struct page_cgroup *pc;
2630        struct mem_cgroup *mem = NULL;
2631        int page_size = PAGE_SIZE;
2632
2633        if (mem_cgroup_disabled())
2634                return NULL;
2635
2636        if (PageSwapCache(page))
2637                return NULL;
2638
2639        if (PageTransHuge(page)) {
2640                page_size <<= compound_order(page);
2641                VM_BUG_ON(!PageTransHuge(page));
2642        }
2643
2644        count = page_size >> PAGE_SHIFT;
2645        /*
2646         * Check if our page_cgroup is valid
2647         */
2648        pc = lookup_page_cgroup(page);
2649        if (unlikely(!pc || !PageCgroupUsed(pc)))
2650                return NULL;
2651
2652        lock_page_cgroup(pc);
2653
2654        mem = pc->mem_cgroup;
2655
2656        if (!PageCgroupUsed(pc))
2657                goto unlock_out;
2658
2659        switch (ctype) {
2660        case MEM_CGROUP_CHARGE_TYPE_MAPPED:
2661        case MEM_CGROUP_CHARGE_TYPE_DROP:
2662                /* See mem_cgroup_prepare_migration() */
2663                if (page_mapped(page) || PageCgroupMigration(pc))
2664                        goto unlock_out;
2665                break;
2666        case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
2667                if (!PageAnon(page)) {  /* Shared memory */
2668                        if (page->mapping && !page_is_file_cache(page))
2669                                goto unlock_out;
2670                } else if (page_mapped(page)) /* Anon */
2671                                goto unlock_out;
2672                break;
2673        default:
2674                break;
2675        }
2676
2677        mem_cgroup_charge_statistics(mem, PageCgroupCache(pc), -count);
2678
2679        ClearPageCgroupUsed(pc);
2680        /*
2681         * pc->mem_cgroup is not cleared here. It will be accessed when it's
2682         * freed from LRU. This is safe because uncharged page is expected not
2683         * to be reused (freed soon). Exception is SwapCache, it's handled by
2684         * special functions.
2685         */
2686
2687        unlock_page_cgroup(pc);
2688        /*
2689         * even after unlock, we have mem->res.usage here and this memcg
2690         * will never be freed.
2691         */
2692        memcg_check_events(mem, page);
2693        if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
2694                mem_cgroup_swap_statistics(mem, true);
2695                mem_cgroup_get(mem);
2696        }
2697        if (!mem_cgroup_is_root(mem))
2698                __do_uncharge(mem, ctype, page_size);
2699
2700        return mem;
2701
2702unlock_out:
2703        unlock_page_cgroup(pc);
2704        return NULL;
2705}
2706
2707void mem_cgroup_uncharge_page(struct page *page)
2708{
2709        /* early check. */
2710        if (page_mapped(page))
2711                return;
2712        if (page->mapping && !PageAnon(page))
2713                return;
2714        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
2715}
2716
2717void mem_cgroup_uncharge_cache_page(struct page *page)
2718{
2719        VM_BUG_ON(page_mapped(page));
2720        VM_BUG_ON(page->mapping);
2721        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
2722}
2723
2724/*
2725 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
2726 * In that cases, pages are freed continuously and we can expect pages
2727 * are in the same memcg. All these calls itself limits the number of
2728 * pages freed at once, then uncharge_start/end() is called properly.
2729 * This may be called prural(2) times in a context,
2730 */
2731
2732void mem_cgroup_uncharge_start(void)
2733{
2734        current->memcg_batch.do_batch++;
2735        /* We can do nest. */
2736        if (current->memcg_batch.do_batch == 1) {
2737                current->memcg_batch.memcg = NULL;
2738                current->memcg_batch.bytes = 0;
2739                current->memcg_batch.memsw_bytes = 0;
2740        }
2741}
2742
2743void mem_cgroup_uncharge_end(void)
2744{
2745        struct memcg_batch_info *batch = &current->memcg_batch;
2746
2747        if (!batch->do_batch)
2748                return;
2749
2750        batch->do_batch--;
2751        if (batch->do_batch) /* If stacked, do nothing. */
2752                return;
2753
2754        if (!batch->memcg)
2755                return;
2756        /*
2757         * This "batch->memcg" is valid without any css_get/put etc...
2758         * bacause we hide charges behind us.
2759         */
2760        if (batch->bytes)
2761                res_counter_uncharge(&batch->memcg->res, batch->bytes);
2762        if (batch->memsw_bytes)
2763                res_counter_uncharge(&batch->memcg->memsw, batch->memsw_bytes);
2764        memcg_oom_recover(batch->memcg);
2765        /* forget this pointer (for sanity check) */
2766        batch->memcg = NULL;
2767}
2768
2769#ifdef CONFIG_SWAP
2770/*
2771 * called after __delete_from_swap_cache() and drop "page" account.
2772 * memcg information is recorded to swap_cgroup of "ent"
2773 */
2774void
2775mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
2776{
2777        struct mem_cgroup *memcg;
2778        int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
2779
2780        if (!swapout) /* this was a swap cache but the swap is unused ! */
2781                ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
2782
2783        memcg = __mem_cgroup_uncharge_common(page, ctype);
2784
2785        /*
2786         * record memcg information,  if swapout && memcg != NULL,
2787         * mem_cgroup_get() was called in uncharge().
2788         */
2789        if (do_swap_account && swapout && memcg)
2790                swap_cgroup_record(ent, css_id(&memcg->css));
2791}
2792#endif
2793
2794#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2795/*
2796 * called from swap_entry_free(). remove record in swap_cgroup and
2797 * uncharge "memsw" account.
2798 */
2799void mem_cgroup_uncharge_swap(swp_entry_t ent)
2800{
2801        struct mem_cgroup *memcg;
2802        unsigned short id;
2803
2804        if (!do_swap_account)
2805                return;
2806
2807        id = swap_cgroup_record(ent, 0);
2808        rcu_read_lock();
2809        memcg = mem_cgroup_lookup(id);
2810        if (memcg) {
2811                /*
2812                 * We uncharge this because swap is freed.
2813                 * This memcg can be obsolete one. We avoid calling css_tryget
2814                 */
2815                if (!mem_cgroup_is_root(memcg))
2816                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
2817                mem_cgroup_swap_statistics(memcg, false);
2818                mem_cgroup_put(memcg);
2819        }
2820        rcu_read_unlock();
2821}
2822
2823/**
2824 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
2825 * @entry: swap entry to be moved
2826 * @from:  mem_cgroup which the entry is moved from
2827 * @to:  mem_cgroup which the entry is moved to
2828 * @need_fixup: whether we should fixup res_counters and refcounts.
2829 *
2830 * It succeeds only when the swap_cgroup's record for this entry is the same
2831 * as the mem_cgroup's id of @from.
2832 *
2833 * Returns 0 on success, -EINVAL on failure.
2834 *
2835 * The caller must have charged to @to, IOW, called res_counter_charge() about
2836 * both res and memsw, and called css_get().
2837 */
2838static int mem_cgroup_move_swap_account(swp_entry_t entry,
2839                struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2840{
2841        unsigned short old_id, new_id;
2842
2843        old_id = css_id(&from->css);
2844        new_id = css_id(&to->css);
2845
2846        if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
2847                mem_cgroup_swap_statistics(from, false);
2848                mem_cgroup_swap_statistics(to, true);
2849                /*
2850                 * This function is only called from task migration context now.
2851                 * It postpones res_counter and refcount handling till the end
2852                 * of task migration(mem_cgroup_clear_mc()) for performance
2853                 * improvement. But we cannot postpone mem_cgroup_get(to)
2854                 * because if the process that has been moved to @to does
2855                 * swap-in, the refcount of @to might be decreased to 0.
2856                 */
2857                mem_cgroup_get(to);
2858                if (need_fixup) {
2859                        if (!mem_cgroup_is_root(from))
2860                                res_counter_uncharge(&from->memsw, PAGE_SIZE);
2861                        mem_cgroup_put(from);
2862                        /*
2863                         * we charged both to->res and to->memsw, so we should
2864                         * uncharge to->res.
2865                         */
2866                        if (!mem_cgroup_is_root(to))
2867                                res_counter_uncharge(&to->res, PAGE_SIZE);
2868                }
2869                return 0;
2870        }
2871        return -EINVAL;
2872}
2873#else
2874static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
2875                struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
2876{
2877        return -EINVAL;
2878}
2879#endif
2880
2881/*
2882 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
2883 * page belongs to.
2884 */
2885int mem_cgroup_prepare_migration(struct page *page,
2886        struct page *newpage, struct mem_cgroup **ptr)
2887{
2888        struct page_cgroup *pc;
2889        struct mem_cgroup *mem = NULL;
2890        enum charge_type ctype;
2891        int ret = 0;
2892
2893        VM_BUG_ON(PageTransHuge(page));
2894        if (mem_cgroup_disabled())
2895                return 0;
2896
2897        pc = lookup_page_cgroup(page);
2898        lock_page_cgroup(pc);
2899        if (PageCgroupUsed(pc)) {
2900                mem = pc->mem_cgroup;
2901                css_get(&mem->css);
2902                /*
2903                 * At migrating an anonymous page, its mapcount goes down
2904                 * to 0 and uncharge() will be called. But, even if it's fully
2905                 * unmapped, migration may fail and this page has to be
2906                 * charged again. We set MIGRATION flag here and delay uncharge
2907                 * until end_migration() is called
2908                 *
2909                 * Corner Case Thinking
2910                 * A)
2911                 * When the old page was mapped as Anon and it's unmap-and-freed
2912                 * while migration was ongoing.
2913                 * If unmap finds the old page, uncharge() of it will be delayed
2914                 * until end_migration(). If unmap finds a new page, it's
2915                 * uncharged when it make mapcount to be 1->0. If unmap code
2916                 * finds swap_migration_entry, the new page will not be mapped
2917                 * and end_migration() will find it(mapcount==0).
2918                 *
2919                 * B)
2920                 * When the old page was mapped but migraion fails, the kernel
2921                 * remaps it. A charge for it is kept by MIGRATION flag even
2922                 * if mapcount goes down to 0. We can do remap successfully
2923                 * without charging it again.
2924                 *
2925                 * C)
2926                 * The "old" page is under lock_page() until the end of
2927                 * migration, so, the old page itself will not be swapped-out.
2928                 * If the new page is swapped out before end_migraton, our
2929                 * hook to usual swap-out path will catch the event.
2930                 */
2931                if (PageAnon(page))
2932                        SetPageCgroupMigration(pc);
2933        }
2934        unlock_page_cgroup(pc);
2935        /*
2936         * If the page is not charged at this point,
2937         * we return here.
2938         */
2939        if (!mem)
2940                return 0;
2941
2942        *ptr = mem;
2943        ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false, PAGE_SIZE);
2944        css_put(&mem->css);/* drop extra refcnt */
2945        if (ret || *ptr == NULL) {
2946                if (PageAnon(page)) {
2947                        lock_page_cgroup(pc);
2948                        ClearPageCgroupMigration(pc);
2949                        unlock_page_cgroup(pc);
2950                        /*
2951                         * The old page may be fully unmapped while we kept it.
2952                         */
2953                        mem_cgroup_uncharge_page(page);
2954                }
2955                return -ENOMEM;
2956        }
2957        /*
2958         * We charge new page before it's used/mapped. So, even if unlock_page()
2959         * is called before end_migration, we can catch all events on this new
2960         * page. In the case new page is migrated but not remapped, new page's
2961         * mapcount will be finally 0 and we call uncharge in end_migration().
2962         */
2963        pc = lookup_page_cgroup(newpage);
2964        if (PageAnon(page))
2965                ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
2966        else if (page_is_file_cache(page))
2967                ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
2968        else
2969                ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
2970        __mem_cgroup_commit_charge(mem, pc, ctype, PAGE_SIZE);
2971        return ret;
2972}
2973
2974/* remove redundant charge if migration failed*/
2975void mem_cgroup_end_migration(struct mem_cgroup *mem,
2976        struct page *oldpage, struct page *newpage, bool migration_ok)
2977{
2978        struct page *used, *unused;
2979        struct page_cgroup *pc;
2980
2981        if (!mem)
2982                return;
2983        /* blocks rmdir() */
2984        cgroup_exclude_rmdir(&mem->css);
2985        if (!migration_ok) {
2986                used = oldpage;
2987                unused = newpage;
2988        } else {
2989                used = newpage;
2990                unused = oldpage;
2991        }
2992        /*
2993         * We disallowed uncharge of pages under migration because mapcount
2994         * of the page goes down to zero, temporarly.
2995         * Clear the flag and check the page should be charged.
2996         */
2997        pc = lookup_page_cgroup(oldpage);
2998        lock_page_cgroup(pc);
2999        ClearPageCgroupMigration(pc);
3000        unlock_page_cgroup(pc);
3001
3002        __mem_cgroup_uncharge_common(unused, MEM_CGROUP_CHARGE_TYPE_FORCE);
3003
3004        /*
3005         * If a page is a file cache, radix-tree replacement is very atomic
3006         * and we can skip this check. When it was an Anon page, its mapcount
3007         * goes down to 0. But because we added MIGRATION flage, it's not
3008         * uncharged yet. There are several case but page->mapcount check
3009         * and USED bit check in mem_cgroup_uncharge_page() will do enough
3010         * check. (see prepare_charge() also)
3011         */
3012        if (PageAnon(used))
3013                mem_cgroup_uncharge_page(used);
3014        /*
3015         * At migration, we may charge account against cgroup which has no
3016         * tasks.
3017         * So, rmdir()->pre_destroy() can be called while we do this charge.
3018         * In that case, we need to call pre_destroy() again. check it here.
3019         */
3020        cgroup_release_and_wakeup_rmdir(&mem->css);
3021}
3022
3023/*
3024 * A call to try to shrink memory usage on charge failure at shmem's swapin.
3025 * Calling hierarchical_reclaim is not enough because we should update
3026 * last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM.
3027 * Moreover considering hierarchy, we should reclaim from the mem_over_limit,
3028 * not from the memcg which this page would be charged to.
3029 * try_charge_swapin does all of these works properly.
3030 */
3031int mem_cgroup_shmem_charge_fallback(struct page *page,
3032                            struct mm_struct *mm,
3033                            gfp_t gfp_mask)
3034{
3035        struct mem_cgroup *mem = NULL;
3036        int ret;
3037
3038        if (mem_cgroup_disabled())
3039                return 0;
3040
3041        ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
3042        if (!ret)
3043                mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */
3044
3045        return ret;
3046}
3047
3048static DEFINE_MUTEX(set_limit_mutex);
3049
3050static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
3051                                unsigned long long val)
3052{
3053        int retry_count;
3054        u64 memswlimit, memlimit;
3055        int ret = 0;
3056        int children = mem_cgroup_count_children(memcg);
3057        u64 curusage, oldusage;
3058        int enlarge;
3059
3060        /*
3061         * For keeping hierarchical_reclaim simple, how long we should retry
3062         * is depends on callers. We set our retry-count to be function
3063         * of # of children which we should visit in this loop.
3064         */
3065        retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
3066
3067        oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
3068
3069        enlarge = 0;
3070        while (retry_count) {
3071                if (signal_pending(current)) {
3072                        ret = -EINTR;
3073                        break;
3074                }
3075                /*
3076                 * Rather than hide all in some function, I do this in
3077                 * open coded manner. You see what this really does.
3078                 * We have to guarantee mem->res.limit < mem->memsw.limit.
3079                 */
3080                mutex_lock(&set_limit_mutex);
3081                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3082                if (memswlimit < val) {
3083                        ret = -EINVAL;
3084                        mutex_unlock(&set_limit_mutex);
3085                        break;
3086                }
3087
3088                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3089                if (memlimit < val)
3090                        enlarge = 1;
3091
3092                ret = res_counter_set_limit(&memcg->res, val);
3093                if (!ret) {
3094                        if (memswlimit == val)
3095                                memcg->memsw_is_minimum = true;
3096                        else
3097                                memcg->memsw_is_minimum = false;
3098                }
3099                mutex_unlock(&set_limit_mutex);
3100
3101                if (!ret)
3102                        break;
3103
3104                mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
3105                                                MEM_CGROUP_RECLAIM_SHRINK);
3106                curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
3107                /* Usage is reduced ? */
3108                if (curusage >= oldusage)
3109                        retry_count--;
3110                else
3111                        oldusage = curusage;
3112        }
3113        if (!ret && enlarge)
3114                memcg_oom_recover(memcg);
3115
3116        return ret;
3117}
3118
3119static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
3120                                        unsigned long long val)
3121{
3122        int retry_count;
3123        u64 memlimit, memswlimit, oldusage, curusage;
3124        int children = mem_cgroup_count_children(memcg);
3125        int ret = -EBUSY;
3126        int enlarge = 0;
3127
3128        /* see mem_cgroup_resize_res_limit */
3129        retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
3130        oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
3131        while (retry_count) {
3132                if (signal_pending(current)) {
3133                        ret = -EINTR;
3134                        break;
3135                }
3136                /*
3137                 * Rather than hide all in some function, I do this in
3138                 * open coded manner. You see what this really does.
3139                 * We have to guarantee mem->res.limit < mem->memsw.limit.
3140                 */
3141                mutex_lock(&set_limit_mutex);
3142                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3143                if (memlimit > val) {
3144                        ret = -EINVAL;
3145                        mutex_unlock(&set_limit_mutex);
3146                        break;
3147                }
3148                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3149                if (memswlimit < val)
3150                        enlarge = 1;
3151                ret = res_counter_set_limit(&memcg->memsw, val);
3152                if (!ret) {
3153                        if (memlimit == val)
3154                                memcg->memsw_is_minimum = true;
3155                        else
3156                                memcg->memsw_is_minimum = false;
3157                }
3158                mutex_unlock(&set_limit_mutex);
3159
3160                if (!ret)
3161                        break;
3162
3163                mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
3164                                                MEM_CGROUP_RECLAIM_NOSWAP |
3165                                                MEM_CGROUP_RECLAIM_SHRINK);
3166                curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
3167                /* Usage is reduced ? */
3168                if (curusage >= oldusage)
3169                        retry_count--;
3170                else
3171                        oldusage = curusage;
3172        }
3173        if (!ret && enlarge)
3174                memcg_oom_recover(memcg);
3175        return ret;
3176}
3177
3178unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
3179                                            gfp_t gfp_mask)
3180{
3181        unsigned long nr_reclaimed = 0;
3182        struct mem_cgroup_per_zone *mz, *next_mz = NULL;
3183        unsigned long reclaimed;
3184        int loop = 0;
3185        struct mem_cgroup_tree_per_zone *mctz;
3186        unsigned long long excess;
3187
3188        if (order > 0)
3189                return 0;
3190
3191        mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
3192        /*
3193         * This loop can run a while, specially if mem_cgroup's continuously
3194         * keep exceeding their soft limit and putting the system under
3195         * pressure
3196         */
3197        do {
3198                if (next_mz)
3199                        mz = next_mz;
3200                else
3201                        mz = mem_cgroup_largest_soft_limit_node(mctz);
3202                if (!mz)
3203                        break;
3204
3205                reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
3206                                                gfp_mask,
3207                                                MEM_CGROUP_RECLAIM_SOFT);
3208                nr_reclaimed += reclaimed;
3209                spin_lock(&mctz->lock);
3210
3211                /*
3212                 * If we failed to reclaim anything from this memory cgroup
3213                 * it is time to move on to the next cgroup
3214                 */
3215                next_mz = NULL;
3216                if (!reclaimed) {
3217                        do {
3218                                /*
3219                                 * Loop until we find yet another one.
3220                                 *
3221                                 * By the time we get the soft_limit lock
3222                                 * again, someone might have aded the
3223                                 * group back on the RB tree. Iterate to
3224                                 * make sure we get a different mem.
3225                                 * mem_cgroup_largest_soft_limit_node returns
3226                                 * NULL if no other cgroup is present on
3227                                 * the tree
3228                                 */
3229                                next_mz =
3230                                __mem_cgroup_largest_soft_limit_node(mctz);
3231                                if (next_mz == mz) {
3232                                        css_put(&next_mz->mem->css);
3233                                        next_mz = NULL;
3234                                } else /* next_mz == NULL or other memcg */
3235                                        break;
3236                        } while (1);
3237                }
3238                __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
3239                excess = res_counter_soft_limit_excess(&mz->mem->res);
3240                /*
3241                 * One school of thought says that we should not add
3242                 * back the node to the tree if reclaim returns 0.
3243                 * But our reclaim could return 0, simply because due
3244                 * to priority we are exposing a smaller subset of
3245                 * memory to reclaim from. Consider this as a longer
3246                 * term TODO.
3247                 */
3248                /* If excess == 0, no tree ops */
3249                __mem_cgroup_insert_exceeded(mz->mem, mz, mctz, excess);
3250                spin_unlock(&mctz->lock);
3251                css_put(&mz->mem->css);
3252                loop++;
3253                /*
3254                 * Could not reclaim anything and there are no more
3255                 * mem cgroups to try or we seem to be looping without
3256                 * reclaiming anything.
3257                 */
3258                if (!nr_reclaimed &&
3259                        (next_mz == NULL ||
3260                        loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
3261                        break;
3262        } while (!nr_reclaimed);
3263        if (next_mz)
3264                css_put(&next_mz->mem->css);
3265        return nr_reclaimed;
3266}
3267
3268/*
3269 * This routine traverse page_cgroup in given list and drop them all.
3270 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
3271 */
3272static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
3273                                int node, int zid, enum lru_list lru)
3274{
3275        struct zone *zone;
3276        struct mem_cgroup_per_zone *mz;
3277        struct page_cgroup *pc, *busy;
3278        unsigned long flags, loop;
3279        struct list_head *list;
3280        int ret = 0;
3281
3282        zone = &NODE_DATA(node)->node_zones[zid];
3283        mz = mem_cgroup_zoneinfo(mem, node, zid);
3284        list = &mz->lists[lru];
3285
3286        loop = MEM_CGROUP_ZSTAT(mz, lru);
3287        /* give some margin against EBUSY etc...*/
3288        loop += 256;
3289        busy = NULL;
3290        while (loop--) {
3291                ret = 0;
3292                spin_lock_irqsave(&zone->lru_lock, flags);
3293                if (list_empty(list)) {
3294                        spin_unlock_irqrestore(&zone->lru_lock, flags);
3295                        break;
3296                }
3297                pc = list_entry(list->prev, struct page_cgroup, lru);
3298                if (busy == pc) {
3299                        list_move(&pc->lru, list);
3300                        busy = NULL;
3301                        spin_unlock_irqrestore(&zone->lru_lock, flags);
3302                        continue;
3303                }
3304                spin_unlock_irqrestore(&zone->lru_lock, flags);
3305
3306                ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
3307                if (ret == -ENOMEM)
3308                        break;
3309
3310                if (ret == -EBUSY || ret == -EINVAL) {
3311                        /* found lock contention or "pc" is obsolete. */
3312                        busy = pc;
3313                        cond_resched();
3314                } else
3315                        busy = NULL;
3316        }
3317
3318        if (!ret && !list_empty(list))
3319                return -EBUSY;
3320        return ret;
3321}
3322
3323/*
3324 * make mem_cgroup's charge to be 0 if there is no task.
3325 * This enables deleting this mem_cgroup.
3326 */
3327static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
3328{
3329        int ret;
3330        int node, zid, shrink;
3331        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
3332        struct cgroup *cgrp = mem->css.cgroup;
3333
3334        css_get(&mem->css);
3335
3336        shrink = 0;
3337        /* should free all ? */
3338        if (free_all)
3339                goto try_to_free;
3340move_account:
3341        do {
3342                ret = -EBUSY;
3343                if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
3344                        goto out;
3345                ret = -EINTR;
3346                if (signal_pending(current))
3347                        goto out;
3348                /* This is for making all *used* pages to be on LRU. */
3349                lru_add_drain_all();
3350                drain_all_stock_sync();
3351                ret = 0;
3352                mem_cgroup_start_move(mem);
3353                for_each_node_state(node, N_HIGH_MEMORY) {
3354                        for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
3355                                enum lru_list l;
3356                                for_each_lru(l) {
3357                                        ret = mem_cgroup_force_empty_list(mem,
3358                                                        node, zid, l);
3359                                        if (ret)
3360                                                break;
3361                                }
3362                        }
3363                        if (ret)
3364                                break;
3365                }
3366                mem_cgroup_end_move(mem);
3367                memcg_oom_recover(mem);
3368                /* it seems parent cgroup doesn't have enough mem */
3369                if (ret == -ENOMEM)
3370                        goto try_to_free;
3371                cond_resched();
3372        /* "ret" should also be checked to ensure all lists are empty. */
3373        } while (mem->res.usage > 0 || ret);
3374out:
3375        css_put(&mem->css);
3376        return ret;
3377
3378try_to_free:
3379        /* returns EBUSY if there is a task or if we come here twice. */
3380        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
3381                ret = -EBUSY;
3382                goto out;
3383        }
3384        /* we call try-to-free pages for make this cgroup empty */
3385        lru_add_drain_all();
3386        /* try to free all pages in this cgroup */
3387        shrink = 1;
3388        while (nr_retries && mem->res.usage > 0) {
3389                int progress;
3390
3391                if (signal_pending(current)) {
3392                        ret = -EINTR;
3393                        goto out;
3394                }
3395                progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
3396                                                false, get_swappiness(mem));
3397                if (!progress) {
3398                        nr_retries--;
3399                        /* maybe some writeback is necessary */
3400                        congestion_wait(BLK_RW_ASYNC, HZ/10);
3401                }
3402
3403        }
3404        lru_add_drain();
3405        /* try move_account...there may be some *locked* pages. */
3406        goto move_account;
3407}
3408
3409int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
3410{
3411        return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
3412}
3413
3414
3415static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
3416{
3417        return mem_cgroup_from_cont(cont)->use_hierarchy;
3418}
3419
3420static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
3421                                        u64 val)
3422{
3423        int retval = 0;
3424        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3425        struct cgroup *parent = cont->parent;
3426        struct mem_cgroup *parent_mem = NULL;
3427
3428        if (parent)
3429                parent_mem = mem_cgroup_from_cont(parent);
3430
3431        cgroup_lock();
3432        /*
3433         * If parent's use_hierarchy is set, we can't make any modifications
3434         * in the child subtrees. If it is unset, then the change can
3435         * occur, provided the current cgroup has no children.
3436         *
3437         * For the root cgroup, parent_mem is NULL, we allow value to be
3438         * set if there are no children.
3439         */
3440        if ((!parent_mem || !parent_mem->use_hierarchy) &&
3441                                (val == 1 || val == 0)) {
3442                if (list_empty(&cont->children))
3443                        mem->use_hierarchy = val;
3444                else
3445                        retval = -EBUSY;
3446        } else
3447                retval = -EINVAL;
3448        cgroup_unlock();
3449
3450        return retval;
3451}
3452
3453
3454static u64 mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
3455                                enum mem_cgroup_stat_index idx)
3456{
3457        struct mem_cgroup *iter;
3458        s64 val = 0;
3459
3460        /* each per cpu's value can be minus.Then, use s64 */
3461        for_each_mem_cgroup_tree(iter, mem)
3462                val += mem_cgroup_read_stat(iter, idx);
3463
3464        if (val < 0) /* race ? */
3465                val = 0;
3466        return val;
3467}
3468
3469static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
3470{
3471        u64 val;
3472
3473        if (!mem_cgroup_is_root(mem)) {
3474                if (!swap)
3475                        return res_counter_read_u64(&mem->res, RES_USAGE);
3476                else
3477                        return res_counter_read_u64(&mem->memsw, RES_USAGE);
3478        }
3479
3480        val = mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE);
3481        val += mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS);
3482
3483        if (swap)
3484                val += mem_cgroup_get_recursive_idx_stat(mem,
3485                                MEM_CGROUP_STAT_SWAPOUT);
3486
3487        return val << PAGE_SHIFT;
3488}
3489
3490static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
3491{
3492        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
3493        u64 val;
3494        int type, name;
3495
3496        type = MEMFILE_TYPE(cft->private);
3497        name = MEMFILE_ATTR(cft->private);
3498        switch (type) {
3499        case _MEM:
3500                if (name == RES_USAGE)
3501                        val = mem_cgroup_usage(mem, false);
3502                else
3503                        val = res_counter_read_u64(&mem->res, name);
3504                break;
3505        case _MEMSWAP:
3506                if (name == RES_USAGE)
3507                        val = mem_cgroup_usage(mem, true);
3508                else
3509                        val = res_counter_read_u64(&mem->memsw, name);
3510                break;
3511        default:
3512                BUG();
3513                break;
3514        }
3515        return val;
3516}
3517/*
3518 * The user of this function is...
3519 * RES_LIMIT.
3520 */
3521static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
3522                            const char *buffer)
3523{
3524        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3525        int type, name;
3526        unsigned long long val;
3527        int ret;
3528
3529        type = MEMFILE_TYPE(cft->private);
3530        name = MEMFILE_ATTR(cft->private);
3531        switch (name) {
3532        case RES_LIMIT:
3533                if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3534                        ret = -EINVAL;
3535                        break;
3536                }
3537                /* This function does all necessary parse...reuse it */
3538                ret = res_counter_memparse_write_strategy(buffer, &val);
3539                if (ret)
3540                        break;
3541                if (type == _MEM)
3542                        ret = mem_cgroup_resize_limit(memcg, val);
3543                else
3544                        ret = mem_cgroup_resize_memsw_limit(memcg, val);
3545                break;
3546        case RES_SOFT_LIMIT:
3547                ret = res_counter_memparse_write_strategy(buffer, &val);
3548                if (ret)
3549                        break;
3550                /*
3551                 * For memsw, soft limits are hard to implement in terms
3552                 * of semantics, for now, we support soft limits for
3553                 * control without swap
3554                 */
3555                if (type == _MEM)
3556                        ret = res_counter_set_soft_limit(&memcg->res, val);
3557                else
3558                        ret = -EINVAL;
3559                break;
3560        default:
3561                ret = -EINVAL; /* should be BUG() ? */
3562                break;
3563        }
3564        return ret;
3565}
3566
3567static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
3568                unsigned long long *mem_limit, unsigned long long *memsw_limit)
3569{
3570        struct cgroup *cgroup;
3571        unsigned long long min_limit, min_memsw_limit, tmp;
3572
3573        min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3574        min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3575        cgroup = memcg->css.cgroup;
3576        if (!memcg->use_hierarchy)
3577                goto out;
3578
3579        while (cgroup->parent) {
3580                cgroup = cgroup->parent;
3581                memcg = mem_cgroup_from_cont(cgroup);
3582                if (!memcg->use_hierarchy)
3583                        break;
3584                tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
3585                min_limit = min(min_limit, tmp);
3586                tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3587                min_memsw_limit = min(min_memsw_limit, tmp);
3588        }
3589out:
3590        *mem_limit = min_limit;
3591        *memsw_limit = min_memsw_limit;
3592        return;
3593}
3594
3595static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
3596{
3597        struct mem_cgroup *mem;
3598        int type, name;
3599
3600        mem = mem_cgroup_from_cont(cont);
3601        type = MEMFILE_TYPE(event);
3602        name = MEMFILE_ATTR(event);
3603        switch (name) {
3604        case RES_MAX_USAGE:
3605                if (type == _MEM)
3606                        res_counter_reset_max(&mem->res);
3607                else
3608                        res_counter_reset_max(&mem->memsw);
3609                break;
3610        case RES_FAILCNT:
3611                if (type == _MEM)
3612                        res_counter_reset_failcnt(&mem->res);
3613                else
3614                        res_counter_reset_failcnt(&mem->memsw);
3615                break;
3616        }
3617
3618        return 0;
3619}
3620
3621static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
3622                                        struct cftype *cft)
3623{
3624        return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
3625}
3626
3627#ifdef CONFIG_MMU
3628static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3629                                        struct cftype *cft, u64 val)
3630{
3631        struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
3632
3633        if (val >= (1 << NR_MOVE_TYPE))
3634                return -EINVAL;
3635        /*
3636         * We check this value several times in both in can_attach() and
3637         * attach(), so we need cgroup lock to prevent this value from being
3638         * inconsistent.
3639         */
3640        cgroup_lock();
3641        mem->move_charge_at_immigrate = val;
3642        cgroup_unlock();
3643
3644        return 0;
3645}
3646#else
3647static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3648                                        struct cftype *cft, u64 val)
3649{
3650        return -ENOSYS;
3651}
3652#endif
3653
3654
3655/* For read statistics */
3656enum {
3657        MCS_CACHE,
3658        MCS_RSS,
3659        MCS_FILE_MAPPED,
3660        MCS_PGPGIN,
3661        MCS_PGPGOUT,
3662        MCS_SWAP,
3663        MCS_INACTIVE_ANON,
3664        MCS_ACTIVE_ANON,
3665        MCS_INACTIVE_FILE,
3666        MCS_ACTIVE_FILE,
3667        MCS_UNEVICTABLE,
3668        NR_MCS_STAT,
3669};
3670
3671struct mcs_total_stat {
3672        s64 stat[NR_MCS_STAT];
3673};
3674
3675struct {
3676        char *local_name;
3677        char *total_name;
3678} memcg_stat_strings[NR_MCS_STAT] = {
3679        {"cache", "total_cache"},
3680        {"rss", "total_rss"},
3681        {"mapped_file", "total_mapped_file"},
3682        {"pgpgin", "total_pgpgin"},
3683        {"pgpgout", "total_pgpgout"},
3684        {"swap", "total_swap"},
3685        {"inactive_anon", "total_inactive_anon"},
3686        {"active_anon", "total_active_anon"},
3687        {"inactive_file", "total_inactive_file"},
3688        {"active_file", "total_active_file"},
3689        {"unevictable", "total_unevictable"}
3690};
3691
3692
3693static void
3694mem_cgroup_get_local_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
3695{
3696        s64 val;
3697
3698        /* per cpu stat */
3699        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
3700        s->stat[MCS_CACHE] += val * PAGE_SIZE;
3701        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
3702        s->stat[MCS_RSS] += val * PAGE_SIZE;
3703        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_MAPPED);
3704        s->stat[MCS_FILE_MAPPED] += val * PAGE_SIZE;
3705        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGIN_COUNT);
3706        s->stat[MCS_PGPGIN] += val;
3707        val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGOUT_COUNT);
3708        s->stat[MCS_PGPGOUT] += val;
3709        if (do_swap_account) {
3710                val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
3711                s->stat[MCS_SWAP] += val * PAGE_SIZE;
3712        }
3713
3714        /* per zone stat */
3715        val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
3716        s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
3717        val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_ANON);
3718        s->stat[MCS_ACTIVE_ANON] += val * PAGE_SIZE;
3719        val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_FILE);
3720        s->stat[MCS_INACTIVE_FILE] += val * PAGE_SIZE;
3721        val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_FILE);
3722        s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE;
3723        val = mem_cgroup_get_local_zonestat(mem, LRU_UNEVICTABLE);
3724        s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE;
3725}
3726
3727static void
3728mem_cgroup_get_total_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
3729{
3730        struct mem_cgroup *iter;
3731
3732        for_each_mem_cgroup_tree(iter, mem)
3733                mem_cgroup_get_local_stat(iter, s);
3734}
3735
3736static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
3737                                 struct cgroup_map_cb *cb)
3738{
3739        struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
3740        struct mcs_total_stat mystat;
3741        int i;
3742
3743        memset(&mystat, 0, sizeof(mystat));
3744        mem_cgroup_get_local_stat(mem_cont, &mystat);
3745
3746        for (i = 0; i < NR_MCS_STAT; i++) {
3747                if (i == MCS_SWAP && !do_swap_account)
3748                        continue;
3749                cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]);
3750        }
3751
3752        /* Hierarchical information */
3753        {
3754                unsigned long long limit, memsw_limit;
3755                memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
3756                cb->fill(cb, "hierarchical_memory_limit", limit);
3757                if (do_swap_account)
3758                        cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
3759        }
3760
3761        memset(&mystat, 0, sizeof(mystat));
3762        mem_cgroup_get_total_stat(mem_cont, &mystat);
3763        for (i = 0; i < NR_MCS_STAT; i++) {
3764                if (i == MCS_SWAP && !do_swap_account)
3765                        continue;
3766                cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]);
3767        }
3768
3769#ifdef CONFIG_DEBUG_VM
3770        cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
3771
3772        {
3773                int nid, zid;
3774                struct mem_cgroup_per_zone *mz;
3775                unsigned long recent_rotated[2] = {0, 0};
3776                unsigned long recent_scanned[2] = {0, 0};
3777
3778                for_each_online_node(nid)
3779                        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
3780                                mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
3781
3782                                recent_rotated[0] +=
3783                                        mz->reclaim_stat.recent_rotated[0];
3784                                recent_rotated[1] +=
3785                                        mz->reclaim_stat.recent_rotated[1];
3786                                recent_scanned[0] +=
3787                                        mz->reclaim_stat.recent_scanned[0];
3788                                recent_scanned[1] +=
3789                                        mz->reclaim_stat.recent_scanned[1];
3790                        }
3791                cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
3792                cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
3793                cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
3794                cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
3795        }
3796#endif
3797
3798        return 0;
3799}
3800
3801static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
3802{
3803        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3804
3805        return get_swappiness(memcg);
3806}
3807
3808static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
3809                                       u64 val)
3810{
3811        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3812        struct mem_cgroup *parent;
3813
3814        if (val > 100)
3815                return -EINVAL;
3816
3817        if (cgrp->parent == NULL)
3818                return -EINVAL;
3819
3820        parent = mem_cgroup_from_cont(cgrp->parent);
3821
3822        cgroup_lock();
3823
3824        /* If under hierarchy, only empty-root can set this value */
3825        if ((parent->use_hierarchy) ||
3826            (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
3827                cgroup_unlock();
3828                return -EINVAL;
3829        }
3830
3831        spin_lock(&memcg->reclaim_param_lock);
3832        memcg->swappiness = val;
3833        spin_unlock(&memcg->reclaim_param_lock);
3834
3835        cgroup_unlock();
3836
3837        return 0;
3838}
3839
3840static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
3841{
3842        struct mem_cgroup_threshold_ary *t;
3843        u64 usage;
3844        int i;
3845
3846        rcu_read_lock();
3847        if (!swap)
3848                t = rcu_dereference(memcg->thresholds.primary);
3849        else
3850                t = rcu_dereference(memcg->memsw_thresholds.primary);
3851
3852        if (!t)
3853                goto unlock;
3854
3855        usage = mem_cgroup_usage(memcg, swap);
3856
3857        /*
3858         * current_threshold points to threshold just below usage.
3859         * If it's not true, a threshold was crossed after last
3860         * call of __mem_cgroup_threshold().
3861         */
3862        i = t->current_threshold;
3863
3864        /*
3865         * Iterate backward over array of thresholds starting from
3866         * current_threshold and check if a threshold is crossed.
3867         * If none of thresholds below usage is crossed, we read
3868         * only one element of the array here.
3869         */
3870        for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
3871                eventfd_signal(t->entries[i].eventfd, 1);
3872
3873        /* i = current_threshold + 1 */
3874        i++;
3875
3876        /*
3877         * Iterate forward over array of thresholds starting from
3878         * current_threshold+1 and check if a threshold is crossed.
3879         * If none of thresholds above usage is crossed, we read
3880         * only one element of the array here.
3881         */
3882        for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
3883                eventfd_signal(t->entries[i].eventfd, 1);
3884
3885        /* Update current_threshold */
3886        t->current_threshold = i - 1;
3887unlock:
3888        rcu_read_unlock();
3889}
3890
3891static void mem_cgroup_threshold(struct mem_cgroup *memcg)
3892{
3893        while (memcg) {
3894                __mem_cgroup_threshold(memcg, false);
3895                if (do_swap_account)
3896                        __mem_cgroup_threshold(memcg, true);
3897
3898                memcg = parent_mem_cgroup(memcg);
3899        }
3900}
3901
3902static int compare_thresholds(const void *a, const void *b)
3903{
3904        const struct mem_cgroup_threshold *_a = a;
3905        const struct mem_cgroup_threshold *_b = b;
3906
3907        return _a->threshold - _b->threshold;
3908}
3909
3910static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem)
3911{
3912        struct mem_cgroup_eventfd_list *ev;
3913
3914        list_for_each_entry(ev, &mem->oom_notify, list)
3915                eventfd_signal(ev->eventfd, 1);
3916        return 0;
3917}
3918
3919static void mem_cgroup_oom_notify(struct mem_cgroup *mem)
3920{
3921        struct mem_cgroup *iter;
3922
3923        for_each_mem_cgroup_tree(iter, mem)
3924                mem_cgroup_oom_notify_cb(iter);
3925}
3926
3927static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
3928        struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
3929{
3930        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3931        struct mem_cgroup_thresholds *thresholds;
3932        struct mem_cgroup_threshold_ary *new;
3933        int type = MEMFILE_TYPE(cft->private);
3934        u64 threshold, usage;
3935        int i, size, ret;
3936
3937        ret = res_counter_memparse_write_strategy(args, &threshold);
3938        if (ret)
3939                return ret;
3940
3941        mutex_lock(&memcg->thresholds_lock);
3942
3943        if (type == _MEM)
3944                thresholds = &memcg->thresholds;
3945        else if (type == _MEMSWAP)
3946                thresholds = &memcg->memsw_thresholds;
3947        else
3948                BUG();
3949
3950        usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
3951
3952        /* Check if a threshold crossed before adding a new one */
3953        if (thresholds->primary)
3954                __mem_cgroup_threshold(memcg, type == _MEMSWAP);
3955
3956        size = thresholds->primary ? thresholds->primary->size + 1 : 1;
3957
3958        /* Allocate memory for new array of thresholds */
3959        new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
3960                        GFP_KERNEL);
3961        if (!new) {
3962                ret = -ENOMEM;
3963                goto unlock;
3964        }
3965        new->size = size;
3966
3967        /* Copy thresholds (if any) to new array */
3968        if (thresholds->primary) {
3969                memcpy(new->entries, thresholds->primary->entries, (size - 1) *
3970                                sizeof(struct mem_cgroup_threshold));
3971        }
3972
3973        /* Add new threshold */
3974        new->entries[size - 1].eventfd = eventfd;
3975        new->entries[size - 1].threshold = threshold;
3976
3977        /* Sort thresholds. Registering of new threshold isn't time-critical */
3978        sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
3979                        compare_thresholds, NULL);
3980
3981        /* Find current threshold */
3982        new->current_threshold = -1;
3983        for (i = 0; i < size; i++) {
3984                if (new->entries[i].threshold < usage) {
3985                        /*
3986                         * new->current_threshold will not be used until
3987                         * rcu_assign_pointer(), so it's safe to increment
3988                         * it here.
3989                         */
3990                        ++new->current_threshold;
3991                }
3992        }
3993
3994        /* Free old spare buffer and save old primary buffer as spare */
3995        kfree(thresholds->spare);
3996        thresholds->spare = thresholds->primary;
3997
3998        rcu_assign_pointer(thresholds->primary, new);
3999
4000        /* To be sure that nobody uses thresholds */
4001        synchronize_rcu();
4002
4003unlock:
4004        mutex_unlock(&memcg->thresholds_lock);
4005
4006        return ret;
4007}
4008
4009static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
4010        struct cftype *cft, struct eventfd_ctx *eventfd)
4011{
4012        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4013        struct mem_cgroup_thresholds *thresholds;
4014        struct mem_cgroup_threshold_ary *new;
4015        int type = MEMFILE_TYPE(cft->private);
4016        u64 usage;
4017        int i, j, size;
4018
4019        mutex_lock(&memcg->thresholds_lock);
4020        if (type == _MEM)
4021                thresholds = &memcg->thresholds;
4022        else if (type == _MEMSWAP)
4023                thresholds = &memcg->memsw_thresholds;
4024        else
4025                BUG();
4026
4027        /*
4028         * Something went wrong if we trying to unregister a threshold
4029         * if we don't have thresholds
4030         */
4031        BUG_ON(!thresholds);
4032
4033        usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
4034
4035        /* Check if a threshold crossed before removing */
4036        __mem_cgroup_threshold(memcg, type == _MEMSWAP);
4037
4038        /* Calculate new number of threshold */
4039        size = 0;
4040        for (i = 0; i < thresholds->primary->size; i++) {
4041                if (thresholds->primary->entries[i].eventfd != eventfd)
4042                        size++;
4043        }
4044
4045        new = thresholds->spare;
4046
4047        /* Set thresholds array to NULL if we don't have thresholds */
4048        if (!size) {
4049                kfree(new);
4050                new = NULL;
4051                goto swap_buffers;
4052        }
4053
4054        new->size = size;
4055
4056        /* Copy thresholds and find current threshold */
4057        new->current_threshold = -1;
4058        for (i = 0, j = 0; i < thresholds->primary->size; i++) {
4059                if (thresholds->primary->entries[i].eventfd == eventfd)
4060                        continue;
4061
4062                new->entries[j] = thresholds->primary->entries[i];
4063                if (new->entries[j].threshold < usage) {
4064                        /*
4065                         * new->current_threshold will not be used
4066                         * until rcu_assign_pointer(), so it's safe to increment
4067                         * it here.
4068                         */
4069                        ++new->current_threshold;
4070                }
4071                j++;
4072        }
4073
4074swap_buffers:
4075        /* Swap primary and spare array */
4076        thresholds->spare = thresholds->primary;
4077        rcu_assign_pointer(thresholds->primary, new);
4078
4079        /* To be sure that nobody uses thresholds */
4080        synchronize_rcu();
4081
4082        mutex_unlock(&memcg->thresholds_lock);
4083}
4084
4085static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
4086        struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
4087{
4088        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4089        struct mem_cgroup_eventfd_list *event;
4090        int type = MEMFILE_TYPE(cft->private);
4091
4092        BUG_ON(type != _OOM_TYPE);
4093        event = kmalloc(sizeof(*event), GFP_KERNEL);
4094        if (!event)
4095                return -ENOMEM;
4096
4097        mutex_lock(&memcg_oom_mutex);
4098
4099        event->eventfd = eventfd;
4100        list_add(&event->list, &memcg->oom_notify);
4101
4102        /* already in OOM ? */
4103        if (atomic_read(&memcg->oom_lock))
4104                eventfd_signal(eventfd, 1);
4105        mutex_unlock(&memcg_oom_mutex);
4106
4107        return 0;
4108}
4109
4110static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
4111        struct cftype *cft, struct eventfd_ctx *eventfd)
4112{
4113        struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
4114        struct mem_cgroup_eventfd_list *ev, *tmp;
4115        int type = MEMFILE_TYPE(cft->private);
4116
4117        BUG_ON(type != _OOM_TYPE);
4118
4119        mutex_lock(&memcg_oom_mutex);
4120
4121        list_for_each_entry_safe(ev, tmp, &mem->oom_notify, list) {
4122                if (ev->eventfd == eventfd) {
4123                        list_del(&ev->list);
4124                        kfree(ev);
4125                }
4126        }
4127
4128        mutex_unlock(&memcg_oom_mutex);
4129}
4130
4131static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
4132        struct cftype *cft,  struct cgroup_map_cb *cb)
4133{
4134        struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
4135
4136        cb->fill(cb, "oom_kill_disable", mem->oom_kill_disable);
4137
4138        if (atomic_read(&mem->oom_lock))
4139                cb->fill(cb, "under_oom", 1);
4140        else
4141                cb->fill(cb, "under_oom", 0);
4142        return 0;
4143}
4144
4145static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
4146        struct cftype *cft, u64 val)
4147{
4148        struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
4149        struct mem_cgroup *parent;
4150
4151        /* cannot set to root cgroup and only 0 and 1 are allowed */
4152        if (!cgrp->parent || !((val == 0) || (val == 1)))
4153                return -EINVAL;
4154
4155        parent = mem_cgroup_from_cont(cgrp->parent);
4156
4157        cgroup_lock();
4158        /* oom-kill-disable is a flag for subhierarchy. */
4159        if ((parent->use_hierarchy) ||
4160            (mem->use_hierarchy && !list_empty(&cgrp->children))) {
4161                cgroup_unlock();
4162                return -EINVAL;
4163        }
4164        mem->oom_kill_disable = val;
4165        if (!val)
4166                memcg_oom_recover(mem);
4167        cgroup_unlock();
4168        return 0;
4169}
4170
4171static struct cftype mem_cgroup_files[] = {
4172        {
4173                .name = "usage_in_bytes",
4174                .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
4175                .read_u64 = mem_cgroup_read,
4176                .register_event = mem_cgroup_usage_register_event,
4177                .unregister_event = mem_cgroup_usage_unregister_event,
4178        },
4179        {
4180                .name = "max_usage_in_bytes",
4181                .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
4182                .trigger = mem_cgroup_reset,
4183                .read_u64 = mem_cgroup_read,
4184        },
4185        {
4186                .name = "limit_in_bytes",
4187                .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
4188                .write_string = mem_cgroup_write,
4189                .read_u64 = mem_cgroup_read,
4190        },
4191        {
4192                .name = "soft_limit_in_bytes",
4193                .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
4194                .write_string = mem_cgroup_write,
4195                .read_u64 = mem_cgroup_read,
4196        },
4197        {
4198                .name = "failcnt",
4199                .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
4200                .trigger = mem_cgroup_reset,
4201                .read_u64 = mem_cgroup_read,
4202        },
4203        {
4204                .name = "stat",
4205                .read_map = mem_control_stat_show,
4206        },
4207        {
4208                .name = "force_empty",
4209                .trigger = mem_cgroup_force_empty_write,
4210        },
4211        {
4212                .name = "use_hierarchy",
4213                .write_u64 = mem_cgroup_hierarchy_write,
4214                .read_u64 = mem_cgroup_hierarchy_read,
4215        },
4216        {
4217                .name = "swappiness",
4218                .read_u64 = mem_cgroup_swappiness_read,
4219                .write_u64 = mem_cgroup_swappiness_write,
4220        },
4221        {
4222                .name = "move_charge_at_immigrate",
4223                .read_u64 = mem_cgroup_move_charge_read,
4224                .write_u64 = mem_cgroup_move_charge_write,
4225        },
4226        {
4227                .name = "oom_control",
4228                .read_map = mem_cgroup_oom_control_read,
4229                .write_u64 = mem_cgroup_oom_control_write,
4230                .register_event = mem_cgroup_oom_register_event,
4231                .unregister_event = mem_cgroup_oom_unregister_event,
4232                .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
4233        },
4234};
4235
4236#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4237static struct cftype memsw_cgroup_files[] = {
4238        {
4239                .name = "memsw.usage_in_bytes",
4240                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
4241                .read_u64 = mem_cgroup_read,
4242                .register_event = mem_cgroup_usage_register_event,
4243                .unregister_event = mem_cgroup_usage_unregister_event,
4244        },
4245        {
4246                .name = "memsw.max_usage_in_bytes",
4247                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
4248                .trigger = mem_cgroup_reset,
4249                .read_u64 = mem_cgroup_read,
4250        },
4251        {
4252                .name = "memsw.limit_in_bytes",
4253                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
4254                .write_string = mem_cgroup_write,
4255                .read_u64 = mem_cgroup_read,
4256        },
4257        {
4258                .name = "memsw.failcnt",
4259                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
4260                .trigger = mem_cgroup_reset,
4261                .read_u64 = mem_cgroup_read,
4262        },
4263};
4264
4265static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
4266{
4267        if (!do_swap_account)
4268                return 0;
4269        return cgroup_add_files(cont, ss, memsw_cgroup_files,
4270                                ARRAY_SIZE(memsw_cgroup_files));
4271};
4272#else
4273static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
4274{
4275        return 0;
4276}
4277#endif
4278
4279static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
4280{
4281        struct mem_cgroup_per_node *pn;
4282        struct mem_cgroup_per_zone *mz;
4283        enum lru_list l;
4284        int zone, tmp = node;
4285        /*
4286         * This routine is called against possible nodes.
4287         * But it's BUG to call kmalloc() against offline node.
4288         *
4289         * TODO: this routine can waste much memory for nodes which will
4290         *       never be onlined. It's better to use memory hotplug callback
4291         *       function.
4292         */
4293        if (!node_state(node, N_NORMAL_MEMORY))
4294                tmp = -1;
4295        pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
4296        if (!pn)
4297                return 1;
4298
4299        mem->info.nodeinfo[node] = pn;
4300        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4301                mz = &pn->zoneinfo[zone];
4302                for_each_lru(l)
4303                        INIT_LIST_HEAD(&mz->lists[l]);
4304                mz->usage_in_excess = 0;
4305                mz->on_tree = false;
4306                mz->mem = mem;
4307        }
4308        return 0;
4309}
4310
4311static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
4312{
4313        kfree(mem->info.nodeinfo[node]);
4314}
4315
4316static struct mem_cgroup *mem_cgroup_alloc(void)
4317{
4318        struct mem_cgroup *mem;
4319        int size = sizeof(struct mem_cgroup);
4320
4321        /* Can be very big if MAX_NUMNODES is very big */
4322        if (size < PAGE_SIZE)
4323                mem = kzalloc(size, GFP_KERNEL);
4324        else
4325                mem = vzalloc(size);
4326
4327        if (!mem)
4328                return NULL;
4329
4330        mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
4331        if (!mem->stat)
4332                goto out_free;
4333        spin_lock_init(&mem->pcp_counter_lock);
4334        return mem;
4335
4336out_free:
4337        if (size < PAGE_SIZE)
4338                kfree(mem);
4339        else
4340                vfree(mem);
4341        return NULL;
4342}
4343
4344/*
4345 * At destroying mem_cgroup, references from swap_cgroup can remain.
4346 * (scanning all at force_empty is too costly...)
4347 *
4348 * Instead of clearing all references at force_empty, we remember
4349 * the number of reference from swap_cgroup and free mem_cgroup when
4350 * it goes down to 0.
4351 *
4352 * Removal of cgroup itself succeeds regardless of refs from swap.
4353 */
4354
4355static void __mem_cgroup_free(struct mem_cgroup *mem)
4356{
4357        int node;
4358
4359        mem_cgroup_remove_from_trees(mem);
4360        free_css_id(&mem_cgroup_subsys, &mem->css);
4361
4362        for_each_node_state(node, N_POSSIBLE)
4363                free_mem_cgroup_per_zone_info(mem, node);
4364
4365        free_percpu(mem->stat);
4366        if (sizeof(struct mem_cgroup) < PAGE_SIZE)
4367                kfree(mem);
4368        else
4369                vfree(mem);
4370}
4371
4372static void mem_cgroup_get(struct mem_cgroup *mem)
4373{
4374        atomic_inc(&mem->refcnt);
4375}
4376
4377static void __mem_cgroup_put(struct mem_cgroup *mem, int count)
4378{
4379        if (atomic_sub_and_test(count, &mem->refcnt)) {
4380                struct mem_cgroup *parent = parent_mem_cgroup(mem);
4381                __mem_cgroup_free(mem);
4382                if (parent)
4383                        mem_cgroup_put(parent);
4384        }
4385}
4386
4387static void mem_cgroup_put(struct mem_cgroup *mem)
4388{
4389        __mem_cgroup_put(mem, 1);
4390}
4391
4392/*
4393 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
4394 */
4395static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem)
4396{
4397        if (!mem->res.parent)
4398                return NULL;
4399        return mem_cgroup_from_res_counter(mem->res.parent, res);
4400}
4401
4402#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4403static void __init enable_swap_cgroup(void)
4404{
4405        if (!mem_cgroup_disabled() && really_do_swap_account)
4406                do_swap_account = 1;
4407}
4408#else
4409static void __init enable_swap_cgroup(void)
4410{
4411}
4412#endif
4413
4414static int mem_cgroup_soft_limit_tree_init(void)
4415{
4416        struct mem_cgroup_tree_per_node *rtpn;
4417        struct mem_cgroup_tree_per_zone *rtpz;
4418        int tmp, node, zone;
4419
4420        for_each_node_state(node, N_POSSIBLE) {
4421                tmp = node;
4422                if (!node_state(node, N_NORMAL_MEMORY))
4423                        tmp = -1;
4424                rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
4425                if (!rtpn)
4426                        return 1;
4427
4428                soft_limit_tree.rb_tree_per_node[node] = rtpn;
4429
4430                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4431                        rtpz = &rtpn->rb_tree_per_zone[zone];
4432                        rtpz->rb_root = RB_ROOT;
4433                        spin_lock_init(&rtpz->lock);
4434                }
4435        }
4436        return 0;
4437}
4438
4439static struct cgroup_subsys_state * __ref
4440mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
4441{
4442        struct mem_cgroup *mem, *parent;
4443        long error = -ENOMEM;
4444        int node;
4445
4446        mem = mem_cgroup_alloc();
4447        if (!mem)
4448                return ERR_PTR(error);
4449
4450        for_each_node_state(node, N_POSSIBLE)
4451                if (alloc_mem_cgroup_per_zone_info(mem, node))
4452                        goto free_out;
4453
4454        /* root ? */
4455        if (cont->parent == NULL) {
4456                int cpu;
4457                enable_swap_cgroup();
4458                parent = NULL;
4459                root_mem_cgroup = mem;
4460                if (mem_cgroup_soft_limit_tree_init())
4461                        goto free_out;
4462                for_each_possible_cpu(cpu) {
4463                        struct memcg_stock_pcp *stock =
4464                                                &per_cpu(memcg_stock, cpu);
4465                        INIT_WORK(&stock->work, drain_local_stock);
4466                }
4467                hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
4468        } else {
4469                parent = mem_cgroup_from_cont(cont->parent);
4470                mem->use_hierarchy = parent->use_hierarchy;
4471                mem->oom_kill_disable = parent->oom_kill_disable;
4472        }
4473
4474        if (parent && parent->use_hierarchy) {
4475                res_counter_init(&mem->res, &parent->res);
4476                res_counter_init(&mem->memsw, &parent->memsw);
4477                /*
4478                 * We increment refcnt of the parent to ensure that we can
4479                 * safely access it on res_counter_charge/uncharge.
4480                 * This refcnt will be decremented when freeing this
4481                 * mem_cgroup(see mem_cgroup_put).
4482                 */
4483                mem_cgroup_get(parent);
4484        } else {
4485                res_counter_init(&mem->res, NULL);
4486                res_counter_init(&mem->memsw, NULL);
4487        }
4488        mem->last_scanned_child = 0;
4489        spin_lock_init(&mem->reclaim_param_lock);
4490        INIT_LIST_HEAD(&mem->oom_notify);
4491
4492        if (parent)
4493                mem->swappiness = get_swappiness(parent);
4494        atomic_set(&mem->refcnt, 1);
4495        mem->move_charge_at_immigrate = 0;
4496        mutex_init(&mem->thresholds_lock);
4497        return &mem->css;
4498free_out:
4499        __mem_cgroup_free(mem);
4500        root_mem_cgroup = NULL;
4501        return ERR_PTR(error);
4502}
4503
4504static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
4505                                        struct cgroup *cont)
4506{
4507        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
4508
4509        return mem_cgroup_force_empty(mem, false);
4510}
4511
4512static void mem_cgroup_destroy(struct cgroup_subsys *ss,
4513                                struct cgroup *cont)
4514{
4515        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
4516
4517        mem_cgroup_put(mem);
4518}
4519
4520static int mem_cgroup_populate(struct cgroup_subsys *ss,
4521                                struct cgroup *cont)
4522{
4523        int ret;
4524
4525        ret = cgroup_add_files(cont, ss, mem_cgroup_files,
4526                                ARRAY_SIZE(mem_cgroup_files));
4527
4528        if (!ret)
4529                ret = register_memsw_files(cont, ss);
4530        return ret;
4531}
4532
4533#ifdef CONFIG_MMU
4534/* Handlers for move charge at task migration. */
4535#define PRECHARGE_COUNT_AT_ONCE 256
4536static int mem_cgroup_do_precharge(unsigned long count)
4537{
4538        int ret = 0;
4539        int batch_count = PRECHARGE_COUNT_AT_ONCE;
4540        struct mem_cgroup *mem = mc.to;
4541
4542        if (mem_cgroup_is_root(mem)) {
4543                mc.precharge += count;
4544                /* we don't need css_get for root */
4545                return ret;
4546        }
4547        /* try to charge at once */
4548        if (count > 1) {
4549                struct res_counter *dummy;
4550                /*
4551                 * "mem" cannot be under rmdir() because we've already checked
4552                 * by cgroup_lock_live_cgroup() that it is not removed and we
4553                 * are still under the same cgroup_mutex. So we can postpone
4554                 * css_get().
4555                 */
4556                if (res_counter_charge(&mem->res, PAGE_SIZE * count, &dummy))
4557                        goto one_by_one;
4558                if (do_swap_account && res_counter_charge(&mem->memsw,
4559                                                PAGE_SIZE * count, &dummy)) {
4560                        res_counter_uncharge(&mem->res, PAGE_SIZE * count);
4561                        goto one_by_one;
4562                }
4563                mc.precharge += count;
4564                return ret;
4565        }
4566one_by_one:
4567        /* fall back to one by one charge */
4568        while (count--) {
4569                if (signal_pending(current)) {
4570                        ret = -EINTR;
4571                        break;
4572                }
4573                if (!batch_count--) {
4574                        batch_count = PRECHARGE_COUNT_AT_ONCE;
4575                        cond_resched();
4576                }
4577                ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
4578                                              PAGE_SIZE);
4579                if (ret || !mem)
4580                        /* mem_cgroup_clear_mc() will do uncharge later */
4581                        return -ENOMEM;
4582                mc.precharge++;
4583        }
4584        return ret;
4585}
4586
4587/**
4588 * is_target_pte_for_mc - check a pte whether it is valid for move charge
4589 * @vma: the vma the pte to be checked belongs
4590 * @addr: the address corresponding to the pte to be checked
4591 * @ptent: the pte to be checked
4592 * @target: the pointer the target page or swap ent will be stored(can be NULL)
4593 *
4594 * Returns
4595 *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
4596 *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
4597 *     move charge. if @target is not NULL, the page is stored in target->page
4598 *     with extra refcnt got(Callers should handle it).
4599 *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
4600 *     target for charge migration. if @target is not NULL, the entry is stored
4601 *     in target->ent.
4602 *
4603 * Called with pte lock held.
4604 */
4605union mc_target {
4606        struct page     *page;
4607        swp_entry_t     ent;
4608};
4609
4610enum mc_target_type {
4611        MC_TARGET_NONE, /* not used */
4612        MC_TARGET_PAGE,
4613        MC_TARGET_SWAP,
4614};
4615
4616static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
4617                                                unsigned long addr, pte_t ptent)
4618{
4619        struct page *page = vm_normal_page(vma, addr, ptent);
4620
4621        if (!page || !page_mapped(page))
4622                return NULL;
4623        if (PageAnon(page)) {
4624                /* we don't move shared anon */
4625                if (!move_anon() || page_mapcount(page) > 2)
4626                        return NULL;
4627        } else if (!move_file())
4628                /* we ignore mapcount for file pages */
4629                return NULL;
4630        if (!get_page_unless_zero(page))
4631                return NULL;
4632
4633        return page;
4634}
4635
4636static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
4637                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
4638{
4639        int usage_count;
4640        struct page *page = NULL;
4641        swp_entry_t ent = pte_to_swp_entry(ptent);
4642
4643        if (!move_anon() || non_swap_entry(ent))
4644                return NULL;
4645        usage_count = mem_cgroup_count_swap_user(ent, &page);
4646        if (usage_count > 1) { /* we don't move shared anon */
4647                if (page)
4648                        put_page(page);
4649                return NULL;
4650        }
4651        if (do_swap_account)
4652                entry->val = ent.val;
4653
4654        return page;
4655}
4656
4657static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
4658                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
4659{
4660        struct page *page = NULL;
4661        struct inode *inode;
4662        struct address_space *mapping;
4663        pgoff_t pgoff;
4664
4665        if (!vma->vm_file) /* anonymous vma */
4666                return NULL;
4667        if (!move_file())
4668                return NULL;
4669
4670        inode = vma->vm_file->f_path.dentry->d_inode;
4671        mapping = vma->vm_file->f_mapping;
4672        if (pte_none(ptent))
4673                pgoff = linear_page_index(vma, addr);
4674        else /* pte_file(ptent) is true */
4675                pgoff = pte_to_pgoff(ptent);
4676
4677        /* page is moved even if it's not RSS of this task(page-faulted). */
4678        if (!mapping_cap_swap_backed(mapping)) { /* normal file */
4679                page = find_get_page(mapping, pgoff);
4680        } else { /* shmem/tmpfs file. we should take account of swap too. */
4681                swp_entry_t ent;
4682                mem_cgroup_get_shmem_target(inode, pgoff, &page, &ent);
4683                if (do_swap_account)
4684                        entry->val = ent.val;
4685        }
4686
4687        return page;
4688}
4689
4690static int is_target_pte_for_mc(struct vm_area_struct *vma,
4691                unsigned long addr, pte_t ptent, union mc_target *target)
4692{
4693        struct page *page = NULL;
4694        struct page_cgroup *pc;
4695        int ret = 0;
4696        swp_entry_t ent = { .val = 0 };
4697
4698        if (pte_present(ptent))
4699                page = mc_handle_present_pte(vma, addr, ptent);
4700        else if (is_swap_pte(ptent))
4701                page = mc_handle_swap_pte(vma, addr, ptent, &ent);
4702        else if (pte_none(ptent) || pte_file(ptent))
4703                page = mc_handle_file_pte(vma, addr, ptent, &ent);
4704
4705        if (!page && !ent.val)
4706                return 0;
4707        if (page) {
4708                pc = lookup_page_cgroup(page);
4709                /*
4710                 * Do only loose check w/o page_cgroup lock.
4711                 * mem_cgroup_move_account() checks the pc is valid or not under
4712                 * the lock.
4713                 */
4714                if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
4715                        ret = MC_TARGET_PAGE;
4716                        if (target)
4717                                target->page = page;
4718                }
4719                if (!ret || !target)
4720                        put_page(page);
4721        }
4722        /* There is a swap entry and a page doesn't exist or isn't charged */
4723        if (ent.val && !ret &&
4724                        css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
4725                ret = MC_TARGET_SWAP;
4726                if (target)
4727                        target->ent = ent;
4728        }
4729        return ret;
4730}
4731
4732static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
4733                                        unsigned long addr, unsigned long end,
4734                                        struct mm_walk *walk)
4735{
4736        struct vm_area_struct *vma = walk->private;
4737        pte_t *pte;
4738        spinlock_t *ptl;
4739
4740        VM_BUG_ON(pmd_trans_huge(*pmd));
4741        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
4742        for (; addr != end; pte++, addr += PAGE_SIZE)
4743                if (is_target_pte_for_mc(vma, addr, *pte, NULL))
4744                        mc.precharge++; /* increment precharge temporarily */
4745        pte_unmap_unlock(pte - 1, ptl);
4746        cond_resched();
4747
4748        return 0;
4749}
4750
4751static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
4752{
4753        unsigned long precharge;
4754        struct vm_area_struct *vma;
4755
4756        down_read(&mm->mmap_sem);
4757        for (vma = mm->mmap; vma; vma = vma->vm_next) {
4758                struct mm_walk mem_cgroup_count_precharge_walk = {
4759                        .pmd_entry = mem_cgroup_count_precharge_pte_range,
4760                        .mm = mm,
4761                        .private = vma,
4762                };
4763                if (is_vm_hugetlb_page(vma))
4764                        continue;
4765                walk_page_range(vma->vm_start, vma->vm_end,
4766                                        &mem_cgroup_count_precharge_walk);
4767        }
4768        up_read(&mm->mmap_sem);
4769
4770        precharge = mc.precharge;
4771        mc.precharge = 0;
4772
4773        return precharge;
4774}
4775
4776static int mem_cgroup_precharge_mc(struct mm_struct *mm)
4777{
4778        unsigned long precharge = mem_cgroup_count_precharge(mm);
4779
4780        VM_BUG_ON(mc.moving_task);
4781        mc.moving_task = current;
4782        return mem_cgroup_do_precharge(precharge);
4783}
4784
4785/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
4786static void __mem_cgroup_clear_mc(void)
4787{
4788        struct mem_cgroup *from = mc.from;
4789        struct mem_cgroup *to = mc.to;
4790
4791        /* we must uncharge all the leftover precharges from mc.to */
4792        if (mc.precharge) {
4793                __mem_cgroup_cancel_charge(mc.to, mc.precharge);
4794                mc.precharge = 0;
4795        }
4796        /*
4797         * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
4798         * we must uncharge here.
4799         */
4800        if (mc.moved_charge) {
4801                __mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
4802                mc.moved_charge = 0;
4803        }
4804        /* we must fixup refcnts and charges */
4805        if (mc.moved_swap) {
4806                /* uncharge swap account from the old cgroup */
4807                if (!mem_cgroup_is_root(mc.from))
4808                        res_counter_uncharge(&mc.from->memsw,
4809                                                PAGE_SIZE * mc.moved_swap);
4810                __mem_cgroup_put(mc.from, mc.moved_swap);
4811
4812                if (!mem_cgroup_is_root(mc.to)) {
4813                        /*
4814                         * we charged both to->res and to->memsw, so we should
4815                         * uncharge to->res.
4816                         */
4817                        res_counter_uncharge(&mc.to->res,
4818                                                PAGE_SIZE * mc.moved_swap);
4819                }
4820                /* we've already done mem_cgroup_get(mc.to) */
4821                mc.moved_swap = 0;
4822        }
4823        memcg_oom_recover(from);
4824        memcg_oom_recover(to);
4825        wake_up_all(&mc.waitq);
4826}
4827
4828static void mem_cgroup_clear_mc(void)
4829{
4830        struct mem_cgroup *from = mc.from;
4831
4832        /*
4833         * we must clear moving_task before waking up waiters at the end of
4834         * task migration.
4835         */
4836        mc.moving_task = NULL;
4837        __mem_cgroup_clear_mc();
4838        spin_lock(&mc.lock);
4839        mc.from = NULL;
4840        mc.to = NULL;
4841        spin_unlock(&mc.lock);
4842        mem_cgroup_end_move(from);
4843}
4844
4845static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
4846                                struct cgroup *cgroup,
4847                                struct task_struct *p,
4848                                bool threadgroup)
4849{
4850        int ret = 0;
4851        struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup);
4852
4853        if (mem->move_charge_at_immigrate) {
4854                struct mm_struct *mm;
4855                struct mem_cgroup *from = mem_cgroup_from_task(p);
4856
4857                VM_BUG_ON(from == mem);
4858
4859                mm = get_task_mm(p);
4860                if (!mm)
4861                        return 0;
4862                /* We move charges only when we move a owner of the mm */
4863                if (mm->owner == p) {
4864                        VM_BUG_ON(mc.from);
4865                        VM_BUG_ON(mc.to);
4866                        VM_BUG_ON(mc.precharge);
4867                        VM_BUG_ON(mc.moved_charge);
4868                        VM_BUG_ON(mc.moved_swap);
4869                        mem_cgroup_start_move(from);
4870                        spin_lock(&mc.lock);
4871                        mc.from = from;
4872                        mc.to = mem;
4873                        spin_unlock(&mc.lock);
4874                        /* We set mc.moving_task later */
4875
4876                        ret = mem_cgroup_precharge_mc(mm);
4877                        if (ret)
4878                                mem_cgroup_clear_mc();
4879                }
4880                mmput(mm);
4881        }
4882        return ret;
4883}
4884
4885static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
4886                                struct cgroup *cgroup,
4887                                struct task_struct *p,
4888                                bool threadgroup)
4889{