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/export.h>
  37#include <linux/mutex.h>
  38#include <linux/rbtree.h>
  39#include <linux/slab.h>
  40#include <linux/swap.h>
  41#include <linux/swapops.h>
  42#include <linux/spinlock.h>
  43#include <linux/eventfd.h>
  44#include <linux/sort.h>
  45#include <linux/fs.h>
  46#include <linux/seq_file.h>
  47#include <linux/vmalloc.h>
  48#include <linux/mm_inline.h>
  49#include <linux/page_cgroup.h>
  50#include <linux/cpu.h>
  51#include <linux/oom.h>
  52#include "internal.h"
  53#include <net/sock.h>
  54#include <net/tcp_memcontrol.h>
  55
  56#include <asm/uaccess.h>
  57
  58#include <trace/events/vmscan.h>
  59
  60struct cgroup_subsys mem_cgroup_subsys __read_mostly;
  61#define MEM_CGROUP_RECLAIM_RETRIES      5
  62static struct mem_cgroup *root_mem_cgroup __read_mostly;
  63
  64#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
  65/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
  66int do_swap_account __read_mostly;
  67
  68/* for remember boot option*/
  69#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED
  70static int really_do_swap_account __initdata = 1;
  71#else
  72static int really_do_swap_account __initdata = 0;
  73#endif
  74
  75#else
  76#define do_swap_account         0
  77#endif
  78
  79
  80/*
  81 * Statistics for memory cgroup.
  82 */
  83enum mem_cgroup_stat_index {
  84        /*
  85         * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
  86         */
  87        MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
  88        MEM_CGROUP_STAT_RSS,       /* # of pages charged as anon rss */
  89        MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
  90        MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
  91        MEM_CGROUP_STAT_NSTATS,
  92};
  93
  94static const char * const mem_cgroup_stat_names[] = {
  95        "cache",
  96        "rss",
  97        "mapped_file",
  98        "swap",
  99};
 100
 101enum mem_cgroup_events_index {
 102        MEM_CGROUP_EVENTS_PGPGIN,       /* # of pages paged in */
 103        MEM_CGROUP_EVENTS_PGPGOUT,      /* # of pages paged out */
 104        MEM_CGROUP_EVENTS_PGFAULT,      /* # of page-faults */
 105        MEM_CGROUP_EVENTS_PGMAJFAULT,   /* # of major page-faults */
 106        MEM_CGROUP_EVENTS_NSTATS,
 107};
 108
 109static const char * const mem_cgroup_events_names[] = {
 110        "pgpgin",
 111        "pgpgout",
 112        "pgfault",
 113        "pgmajfault",
 114};
 115
 116/*
 117 * Per memcg event counter is incremented at every pagein/pageout. With THP,
 118 * it will be incremated by the number of pages. This counter is used for
 119 * for trigger some periodic events. This is straightforward and better
 120 * than using jiffies etc. to handle periodic memcg event.
 121 */
 122enum mem_cgroup_events_target {
 123        MEM_CGROUP_TARGET_THRESH,
 124        MEM_CGROUP_TARGET_SOFTLIMIT,
 125        MEM_CGROUP_TARGET_NUMAINFO,
 126        MEM_CGROUP_NTARGETS,
 127};
 128#define THRESHOLDS_EVENTS_TARGET 128
 129#define SOFTLIMIT_EVENTS_TARGET 1024
 130#define NUMAINFO_EVENTS_TARGET  1024
 131
 132struct mem_cgroup_stat_cpu {
 133        long count[MEM_CGROUP_STAT_NSTATS];
 134        unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
 135        unsigned long nr_page_events;
 136        unsigned long targets[MEM_CGROUP_NTARGETS];
 137};
 138
 139struct mem_cgroup_reclaim_iter {
 140        /* css_id of the last scanned hierarchy member */
 141        int position;
 142        /* scan generation, increased every round-trip */
 143        unsigned int generation;
 144};
 145
 146/*
 147 * per-zone information in memory controller.
 148 */
 149struct mem_cgroup_per_zone {
 150        struct lruvec           lruvec;
 151        unsigned long           lru_size[NR_LRU_LISTS];
 152
 153        struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];
 154
 155        struct rb_node          tree_node;      /* RB tree node */
 156        unsigned long long      usage_in_excess;/* Set to the value by which */
 157                                                /* the soft limit is exceeded*/
 158        bool                    on_tree;
 159        struct mem_cgroup       *memcg;         /* Back pointer, we cannot */
 160                                                /* use container_of        */
 161};
 162
 163struct mem_cgroup_per_node {
 164        struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
 165};
 166
 167struct mem_cgroup_lru_info {
 168        struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
 169};
 170
 171/*
 172 * Cgroups above their limits are maintained in a RB-Tree, independent of
 173 * their hierarchy representation
 174 */
 175
 176struct mem_cgroup_tree_per_zone {
 177        struct rb_root rb_root;
 178        spinlock_t lock;
 179};
 180
 181struct mem_cgroup_tree_per_node {
 182        struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
 183};
 184
 185struct mem_cgroup_tree {
 186        struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
 187};
 188
 189static struct mem_cgroup_tree soft_limit_tree __read_mostly;
 190
 191struct mem_cgroup_threshold {
 192        struct eventfd_ctx *eventfd;
 193        u64 threshold;
 194};
 195
 196/* For threshold */
 197struct mem_cgroup_threshold_ary {
 198        /* An array index points to threshold just below or equal to usage. */
 199        int current_threshold;
 200        /* Size of entries[] */
 201        unsigned int size;
 202        /* Array of thresholds */
 203        struct mem_cgroup_threshold entries[0];
 204};
 205
 206struct mem_cgroup_thresholds {
 207        /* Primary thresholds array */
 208        struct mem_cgroup_threshold_ary *primary;
 209        /*
 210         * Spare threshold array.
 211         * This is needed to make mem_cgroup_unregister_event() "never fail".
 212         * It must be able to store at least primary->size - 1 entries.
 213         */
 214        struct mem_cgroup_threshold_ary *spare;
 215};
 216
 217/* for OOM */
 218struct mem_cgroup_eventfd_list {
 219        struct list_head list;
 220        struct eventfd_ctx *eventfd;
 221};
 222
 223static void mem_cgroup_threshold(struct mem_cgroup *memcg);
 224static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
 225
 226/*
 227 * The memory controller data structure. The memory controller controls both
 228 * page cache and RSS per cgroup. We would eventually like to provide
 229 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
 230 * to help the administrator determine what knobs to tune.
 231 *
 232 * TODO: Add a water mark for the memory controller. Reclaim will begin when
 233 * we hit the water mark. May be even add a low water mark, such that
 234 * no reclaim occurs from a cgroup at it's low water mark, this is
 235 * a feature that will be implemented much later in the future.
 236 */
 237struct mem_cgroup {
 238        struct cgroup_subsys_state css;
 239        /*
 240         * the counter to account for memory usage
 241         */
 242        struct res_counter res;
 243
 244        union {
 245                /*
 246                 * the counter to account for mem+swap usage.
 247                 */
 248                struct res_counter memsw;
 249
 250                /*
 251                 * rcu_freeing is used only when freeing struct mem_cgroup,
 252                 * so put it into a union to avoid wasting more memory.
 253                 * It must be disjoint from the css field.  It could be
 254                 * in a union with the res field, but res plays a much
 255                 * larger part in mem_cgroup life than memsw, and might
 256                 * be of interest, even at time of free, when debugging.
 257                 * So share rcu_head with the less interesting memsw.
 258                 */
 259                struct rcu_head rcu_freeing;
 260                /*
 261                 * We also need some space for a worker in deferred freeing.
 262                 * By the time we call it, rcu_freeing is no longer in use.
 263                 */
 264                struct work_struct work_freeing;
 265        };
 266
 267        /*
 268         * Per cgroup active and inactive list, similar to the
 269         * per zone LRU lists.
 270         */
 271        struct mem_cgroup_lru_info info;
 272        int last_scanned_node;
 273#if MAX_NUMNODES > 1
 274        nodemask_t      scan_nodes;
 275        atomic_t        numainfo_events;
 276        atomic_t        numainfo_updating;
 277#endif
 278        /*
 279         * Should the accounting and control be hierarchical, per subtree?
 280         */
 281        bool use_hierarchy;
 282
 283        bool            oom_lock;
 284        atomic_t        under_oom;
 285
 286        atomic_t        refcnt;
 287
 288        int     swappiness;
 289        /* OOM-Killer disable */
 290        int             oom_kill_disable;
 291
 292        /* set when res.limit == memsw.limit */
 293        bool            memsw_is_minimum;
 294
 295        /* protect arrays of thresholds */
 296        struct mutex thresholds_lock;
 297
 298        /* thresholds for memory usage. RCU-protected */
 299        struct mem_cgroup_thresholds thresholds;
 300
 301        /* thresholds for mem+swap usage. RCU-protected */
 302        struct mem_cgroup_thresholds memsw_thresholds;
 303
 304        /* For oom notifier event fd */
 305        struct list_head oom_notify;
 306
 307        /*
 308         * Should we move charges of a task when a task is moved into this
 309         * mem_cgroup ? And what type of charges should we move ?
 310         */
 311        unsigned long   move_charge_at_immigrate;
 312        /*
 313         * set > 0 if pages under this cgroup are moving to other cgroup.
 314         */
 315        atomic_t        moving_account;
 316        /* taken only while moving_account > 0 */
 317        spinlock_t      move_lock;
 318        /*
 319         * percpu counter.
 320         */
 321        struct mem_cgroup_stat_cpu __percpu *stat;
 322        /*
 323         * used when a cpu is offlined or other synchronizations
 324         * See mem_cgroup_read_stat().
 325         */
 326        struct mem_cgroup_stat_cpu nocpu_base;
 327        spinlock_t pcp_counter_lock;
 328
 329#ifdef CONFIG_INET
 330        struct tcp_memcontrol tcp_mem;
 331#endif
 332};
 333
 334/* Stuffs for move charges at task migration. */
 335/*
 336 * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
 337 * left-shifted bitmap of these types.
 338 */
 339enum move_type {
 340        MOVE_CHARGE_TYPE_ANON,  /* private anonymous page and swap of it */
 341        MOVE_CHARGE_TYPE_FILE,  /* file page(including tmpfs) and swap of it */
 342        NR_MOVE_TYPE,
 343};
 344
 345/* "mc" and its members are protected by cgroup_mutex */
 346static struct move_charge_struct {
 347        spinlock_t        lock; /* for from, to */
 348        struct mem_cgroup *from;
 349        struct mem_cgroup *to;
 350        unsigned long precharge;
 351        unsigned long moved_charge;
 352        unsigned long moved_swap;
 353        struct task_struct *moving_task;        /* a task moving charges */
 354        wait_queue_head_t waitq;                /* a waitq for other context */
 355} mc = {
 356        .lock = __SPIN_LOCK_UNLOCKED(mc.lock),
 357        .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
 358};
 359
 360static bool move_anon(void)
 361{
 362        return test_bit(MOVE_CHARGE_TYPE_ANON,
 363                                        &mc.to->move_charge_at_immigrate);
 364}
 365
 366static bool move_file(void)
 367{
 368        return test_bit(MOVE_CHARGE_TYPE_FILE,
 369                                        &mc.to->move_charge_at_immigrate);
 370}
 371
 372/*
 373 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
 374 * limit reclaim to prevent infinite loops, if they ever occur.
 375 */
 376#define MEM_CGROUP_MAX_RECLAIM_LOOPS            100
 377#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2
 378
 379enum charge_type {
 380        MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
 381        MEM_CGROUP_CHARGE_TYPE_MAPPED,
 382        MEM_CGROUP_CHARGE_TYPE_SHMEM,   /* used by page migration of shmem */
 383        MEM_CGROUP_CHARGE_TYPE_FORCE,   /* used by force_empty */
 384        MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
 385        MEM_CGROUP_CHARGE_TYPE_DROP,    /* a page was unused swap cache */
 386        NR_CHARGE_TYPE,
 387};
 388
 389/* for encoding cft->private value on file */
 390#define _MEM                    (0)
 391#define _MEMSWAP                (1)
 392#define _OOM_TYPE               (2)
 393#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
 394#define MEMFILE_TYPE(val)       ((val) >> 16 & 0xffff)
 395#define MEMFILE_ATTR(val)       ((val) & 0xffff)
 396/* Used for OOM nofiier */
 397#define OOM_CONTROL             (0)
 398
 399/*
 400 * Reclaim flags for mem_cgroup_hierarchical_reclaim
 401 */
 402#define MEM_CGROUP_RECLAIM_NOSWAP_BIT   0x0
 403#define MEM_CGROUP_RECLAIM_NOSWAP       (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
 404#define MEM_CGROUP_RECLAIM_SHRINK_BIT   0x1
 405#define MEM_CGROUP_RECLAIM_SHRINK       (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
 406
 407static void mem_cgroup_get(struct mem_cgroup *memcg);
 408static void mem_cgroup_put(struct mem_cgroup *memcg);
 409
 410/* Writing them here to avoid exposing memcg's inner layout */
 411#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
 412#include <net/sock.h>
 413#include <net/ip.h>
 414
 415static bool mem_cgroup_is_root(struct mem_cgroup *memcg);
 416void sock_update_memcg(struct sock *sk)
 417{
 418        if (mem_cgroup_sockets_enabled) {
 419                struct mem_cgroup *memcg;
 420                struct cg_proto *cg_proto;
 421
 422                BUG_ON(!sk->sk_prot->proto_cgroup);
 423
 424                /* Socket cloning can throw us here with sk_cgrp already
 425                 * filled. It won't however, necessarily happen from
 426                 * process context. So the test for root memcg given
 427                 * the current task's memcg won't help us in this case.
 428                 *
 429                 * Respecting the original socket's memcg is a better
 430                 * decision in this case.
 431                 */
 432                if (sk->sk_cgrp) {
 433                        BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
 434                        mem_cgroup_get(sk->sk_cgrp->memcg);
 435                        return;
 436                }
 437
 438                rcu_read_lock();
 439                memcg = mem_cgroup_from_task(current);
 440                cg_proto = sk->sk_prot->proto_cgroup(memcg);
 441                if (!mem_cgroup_is_root(memcg) && memcg_proto_active(cg_proto)) {
 442                        mem_cgroup_get(memcg);
 443                        sk->sk_cgrp = cg_proto;
 444                }
 445                rcu_read_unlock();
 446        }
 447}
 448EXPORT_SYMBOL(sock_update_memcg);
 449
 450void sock_release_memcg(struct sock *sk)
 451{
 452        if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
 453                struct mem_cgroup *memcg;
 454                WARN_ON(!sk->sk_cgrp->memcg);
 455                memcg = sk->sk_cgrp->memcg;
 456                mem_cgroup_put(memcg);
 457        }
 458}
 459
 460#ifdef CONFIG_INET
 461struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
 462{
 463        if (!memcg || mem_cgroup_is_root(memcg))
 464                return NULL;
 465
 466        return &memcg->tcp_mem.cg_proto;
 467}
 468EXPORT_SYMBOL(tcp_proto_cgroup);
 469#endif /* CONFIG_INET */
 470#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
 471
 472#if defined(CONFIG_INET) && defined(CONFIG_CGROUP_MEM_RES_CTLR_KMEM)
 473static void disarm_sock_keys(struct mem_cgroup *memcg)
 474{
 475        if (!memcg_proto_activated(&memcg->tcp_mem.cg_proto))
 476                return;
 477        static_key_slow_dec(&memcg_socket_limit_enabled);
 478}
 479#else
 480static void disarm_sock_keys(struct mem_cgroup *memcg)
 481{
 482}
 483#endif
 484
 485static void drain_all_stock_async(struct mem_cgroup *memcg);
 486
 487static struct mem_cgroup_per_zone *
 488mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
 489{
 490        return &memcg->info.nodeinfo[nid]->zoneinfo[zid];
 491}
 492
 493struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
 494{
 495        return &memcg->css;
 496}
 497
 498static struct mem_cgroup_per_zone *
 499page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
 500{
 501        int nid = page_to_nid(page);
 502        int zid = page_zonenum(page);
 503
 504        return mem_cgroup_zoneinfo(memcg, nid, zid);
 505}
 506
 507static struct mem_cgroup_tree_per_zone *
 508soft_limit_tree_node_zone(int nid, int zid)
 509{
 510        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
 511}
 512
 513static struct mem_cgroup_tree_per_zone *
 514soft_limit_tree_from_page(struct page *page)
 515{
 516        int nid = page_to_nid(page);
 517        int zid = page_zonenum(page);
 518
 519        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
 520}
 521
 522static void
 523__mem_cgroup_insert_exceeded(struct mem_cgroup *memcg,
 524                                struct mem_cgroup_per_zone *mz,
 525                                struct mem_cgroup_tree_per_zone *mctz,
 526                                unsigned long long new_usage_in_excess)
 527{
 528        struct rb_node **p = &mctz->rb_root.rb_node;
 529        struct rb_node *parent = NULL;
 530        struct mem_cgroup_per_zone *mz_node;
 531
 532        if (mz->on_tree)
 533                return;
 534
 535        mz->usage_in_excess = new_usage_in_excess;
 536        if (!mz->usage_in_excess)
 537                return;
 538        while (*p) {
 539                parent = *p;
 540                mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
 541                                        tree_node);
 542                if (mz->usage_in_excess < mz_node->usage_in_excess)
 543                        p = &(*p)->rb_left;
 544                /*
 545                 * We can't avoid mem cgroups that are over their soft
 546                 * limit by the same amount
 547                 */
 548                else if (mz->usage_in_excess >= mz_node->usage_in_excess)
 549                        p = &(*p)->rb_right;
 550        }
 551        rb_link_node(&mz->tree_node, parent, p);
 552        rb_insert_color(&mz->tree_node, &mctz->rb_root);
 553        mz->on_tree = true;
 554}
 555
 556static void
 557__mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
 558                                struct mem_cgroup_per_zone *mz,
 559                                struct mem_cgroup_tree_per_zone *mctz)
 560{
 561        if (!mz->on_tree)
 562                return;
 563        rb_erase(&mz->tree_node, &mctz->rb_root);
 564        mz->on_tree = false;
 565}
 566
 567static void
 568mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
 569                                struct mem_cgroup_per_zone *mz,
 570                                struct mem_cgroup_tree_per_zone *mctz)
 571{
 572        spin_lock(&mctz->lock);
 573        __mem_cgroup_remove_exceeded(memcg, mz, mctz);
 574        spin_unlock(&mctz->lock);
 575}
 576
 577
 578static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
 579{
 580        unsigned long long excess;
 581        struct mem_cgroup_per_zone *mz;
 582        struct mem_cgroup_tree_per_zone *mctz;
 583        int nid = page_to_nid(page);
 584        int zid = page_zonenum(page);
 585        mctz = soft_limit_tree_from_page(page);
 586
 587        /*
 588         * Necessary to update all ancestors when hierarchy is used.
 589         * because their event counter is not touched.
 590         */
 591        for (; memcg; memcg = parent_mem_cgroup(memcg)) {
 592                mz = mem_cgroup_zoneinfo(memcg, nid, zid);
 593                excess = res_counter_soft_limit_excess(&memcg->res);
 594                /*
 595                 * We have to update the tree if mz is on RB-tree or
 596                 * mem is over its softlimit.
 597                 */
 598                if (excess || mz->on_tree) {
 599                        spin_lock(&mctz->lock);
 600                        /* if on-tree, remove it */
 601                        if (mz->on_tree)
 602                                __mem_cgroup_remove_exceeded(memcg, mz, mctz);
 603                        /*
 604                         * Insert again. mz->usage_in_excess will be updated.
 605                         * If excess is 0, no tree ops.
 606                         */
 607                        __mem_cgroup_insert_exceeded(memcg, mz, mctz, excess);
 608                        spin_unlock(&mctz->lock);
 609                }
 610        }
 611}
 612
 613static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
 614{
 615        int node, zone;
 616        struct mem_cgroup_per_zone *mz;
 617        struct mem_cgroup_tree_per_zone *mctz;
 618
 619        for_each_node(node) {
 620                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
 621                        mz = mem_cgroup_zoneinfo(memcg, node, zone);
 622                        mctz = soft_limit_tree_node_zone(node, zone);
 623                        mem_cgroup_remove_exceeded(memcg, mz, mctz);
 624                }
 625        }
 626}
 627
 628static struct mem_cgroup_per_zone *
 629__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 630{
 631        struct rb_node *rightmost = NULL;
 632        struct mem_cgroup_per_zone *mz;
 633
 634retry:
 635        mz = NULL;
 636        rightmost = rb_last(&mctz->rb_root);
 637        if (!rightmost)
 638                goto done;              /* Nothing to reclaim from */
 639
 640        mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
 641        /*
 642         * Remove the node now but someone else can add it back,
 643         * we will to add it back at the end of reclaim to its correct
 644         * position in the tree.
 645         */
 646        __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
 647        if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
 648                !css_tryget(&mz->memcg->css))
 649                goto retry;
 650done:
 651        return mz;
 652}
 653
 654static struct mem_cgroup_per_zone *
 655mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 656{
 657        struct mem_cgroup_per_zone *mz;
 658
 659        spin_lock(&mctz->lock);
 660        mz = __mem_cgroup_largest_soft_limit_node(mctz);
 661        spin_unlock(&mctz->lock);
 662        return mz;
 663}
 664
 665/*
 666 * Implementation Note: reading percpu statistics for memcg.
 667 *
 668 * Both of vmstat[] and percpu_counter has threshold and do periodic
 669 * synchronization to implement "quick" read. There are trade-off between
 670 * reading cost and precision of value. Then, we may have a chance to implement
 671 * a periodic synchronizion of counter in memcg's counter.
 672 *
 673 * But this _read() function is used for user interface now. The user accounts
 674 * memory usage by memory cgroup and he _always_ requires exact value because
 675 * he accounts memory. Even if we provide quick-and-fuzzy read, we always
 676 * have to visit all online cpus and make sum. So, for now, unnecessary
 677 * synchronization is not implemented. (just implemented for cpu hotplug)
 678 *
 679 * If there are kernel internal actions which can make use of some not-exact
 680 * value, and reading all cpu value can be performance bottleneck in some
 681 * common workload, threashold and synchonization as vmstat[] should be
 682 * implemented.
 683 */
 684static long mem_cgroup_read_stat(struct mem_cgroup *memcg,
 685                                 enum mem_cgroup_stat_index idx)
 686{
 687        long val = 0;
 688        int cpu;
 689
 690        get_online_cpus();
 691        for_each_online_cpu(cpu)
 692                val += per_cpu(memcg->stat->count[idx], cpu);
 693#ifdef CONFIG_HOTPLUG_CPU
 694        spin_lock(&memcg->pcp_counter_lock);
 695        val += memcg->nocpu_base.count[idx];
 696        spin_unlock(&memcg->pcp_counter_lock);
 697#endif
 698        put_online_cpus();
 699        return val;
 700}
 701
 702static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
 703                                         bool charge)
 704{
 705        int val = (charge) ? 1 : -1;
 706        this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
 707}
 708
 709static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
 710                                            enum mem_cgroup_events_index idx)
 711{
 712        unsigned long val = 0;
 713        int cpu;
 714
 715        for_each_online_cpu(cpu)
 716                val += per_cpu(memcg->stat->events[idx], cpu);
 717#ifdef CONFIG_HOTPLUG_CPU
 718        spin_lock(&memcg->pcp_counter_lock);
 719        val += memcg->nocpu_base.events[idx];
 720        spin_unlock(&memcg->pcp_counter_lock);
 721#endif
 722        return val;
 723}
 724
 725static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
 726                                         bool anon, int nr_pages)
 727{
 728        preempt_disable();
 729
 730        /*
 731         * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
 732         * counted as CACHE even if it's on ANON LRU.
 733         */
 734        if (anon)
 735                __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
 736                                nr_pages);
 737        else
 738                __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
 739                                nr_pages);
 740
 741        /* pagein of a big page is an event. So, ignore page size */
 742        if (nr_pages > 0)
 743                __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
 744        else {
 745                __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
 746                nr_pages = -nr_pages; /* for event */
 747        }
 748
 749        __this_cpu_add(memcg->stat->nr_page_events, nr_pages);
 750
 751        preempt_enable();
 752}
 753
 754unsigned long
 755mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
 756{
 757        struct mem_cgroup_per_zone *mz;
 758
 759        mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
 760        return mz->lru_size[lru];
 761}
 762
 763static unsigned long
 764mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
 765                        unsigned int lru_mask)
 766{
 767        struct mem_cgroup_per_zone *mz;
 768        enum lru_list lru;
 769        unsigned long ret = 0;
 770
 771        mz = mem_cgroup_zoneinfo(memcg, nid, zid);
 772
 773        for_each_lru(lru) {
 774                if (BIT(lru) & lru_mask)
 775                        ret += mz->lru_size[lru];
 776        }
 777        return ret;
 778}
 779
 780static unsigned long
 781mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
 782                        int nid, unsigned int lru_mask)
 783{
 784        u64 total = 0;
 785        int zid;
 786
 787        for (zid = 0; zid < MAX_NR_ZONES; zid++)
 788                total += mem_cgroup_zone_nr_lru_pages(memcg,
 789                                                nid, zid, lru_mask);
 790
 791        return total;
 792}
 793
 794static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
 795                        unsigned int lru_mask)
 796{
 797        int nid;
 798        u64 total = 0;
 799
 800        for_each_node_state(nid, N_HIGH_MEMORY)
 801                total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
 802        return total;
 803}
 804
 805static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
 806                                       enum mem_cgroup_events_target target)
 807{
 808        unsigned long val, next;
 809
 810        val = __this_cpu_read(memcg->stat->nr_page_events);
 811        next = __this_cpu_read(memcg->stat->targets[target]);
 812        /* from time_after() in jiffies.h */
 813        if ((long)next - (long)val < 0) {
 814                switch (target) {
 815                case MEM_CGROUP_TARGET_THRESH:
 816                        next = val + THRESHOLDS_EVENTS_TARGET;
 817                        break;
 818                case MEM_CGROUP_TARGET_SOFTLIMIT:
 819                        next = val + SOFTLIMIT_EVENTS_TARGET;
 820                        break;
 821                case MEM_CGROUP_TARGET_NUMAINFO:
 822                        next = val + NUMAINFO_EVENTS_TARGET;
 823                        break;
 824                default:
 825                        break;
 826                }
 827                __this_cpu_write(memcg->stat->targets[target], next);
 828                return true;
 829        }
 830        return false;
 831}
 832
 833/*
 834 * Check events in order.
 835 *
 836 */
 837static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
 838{
 839        preempt_disable();
 840        /* threshold event is triggered in finer grain than soft limit */
 841        if (unlikely(mem_cgroup_event_ratelimit(memcg,
 842                                                MEM_CGROUP_TARGET_THRESH))) {
 843                bool do_softlimit;
 844                bool do_numainfo __maybe_unused;
 845
 846                do_softlimit = mem_cgroup_event_ratelimit(memcg,
 847                                                MEM_CGROUP_TARGET_SOFTLIMIT);
 848#if MAX_NUMNODES > 1
 849                do_numainfo = mem_cgroup_event_ratelimit(memcg,
 850                                                MEM_CGROUP_TARGET_NUMAINFO);
 851#endif
 852                preempt_enable();
 853
 854                mem_cgroup_threshold(memcg);
 855                if (unlikely(do_softlimit))
 856                        mem_cgroup_update_tree(memcg, page);
 857#if MAX_NUMNODES > 1
 858                if (unlikely(do_numainfo))
 859                        atomic_inc(&memcg->numainfo_events);
 860#endif
 861        } else
 862                preempt_enable();
 863}
 864
 865struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 866{
 867        return container_of(cgroup_subsys_state(cont,
 868                                mem_cgroup_subsys_id), struct mem_cgroup,
 869                                css);
 870}
 871
 872struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 873{
 874        /*
 875         * mm_update_next_owner() may clear mm->owner to NULL
 876         * if it races with swapoff, page migration, etc.
 877         * So this can be called with p == NULL.
 878         */
 879        if (unlikely(!p))
 880                return NULL;
 881
 882        return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
 883                                struct mem_cgroup, css);
 884}
 885
 886struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 887{
 888        struct mem_cgroup *memcg = NULL;
 889
 890        if (!mm)
 891                return NULL;
 892        /*
 893         * Because we have no locks, mm->owner's may be being moved to other
 894         * cgroup. We use css_tryget() here even if this looks
 895         * pessimistic (rather than adding locks here).
 896         */
 897        rcu_read_lock();
 898        do {
 899                memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
 900                if (unlikely(!memcg))
 901                        break;
 902        } while (!css_tryget(&memcg->css));
 903        rcu_read_unlock();
 904        return memcg;
 905}
 906
 907/**
 908 * mem_cgroup_iter - iterate over memory cgroup hierarchy
 909 * @root: hierarchy root
 910 * @prev: previously returned memcg, NULL on first invocation
 911 * @reclaim: cookie for shared reclaim walks, NULL for full walks
 912 *
 913 * Returns references to children of the hierarchy below @root, or
 914 * @root itself, or %NULL after a full round-trip.
 915 *
 916 * Caller must pass the return value in @prev on subsequent
 917 * invocations for reference counting, or use mem_cgroup_iter_break()
 918 * to cancel a hierarchy walk before the round-trip is complete.
 919 *
 920 * Reclaimers can specify a zone and a priority level in @reclaim to
 921 * divide up the memcgs in the hierarchy among all concurrent
 922 * reclaimers operating on the same zone and priority.
 923 */
 924struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 925                                   struct mem_cgroup *prev,
 926                                   struct mem_cgroup_reclaim_cookie *reclaim)
 927{
 928        struct mem_cgroup *memcg = NULL;
 929        int id = 0;
 930
 931        if (mem_cgroup_disabled())
 932                return NULL;
 933
 934        if (!root)
 935                root = root_mem_cgroup;
 936
 937        if (prev && !reclaim)
 938                id = css_id(&prev->css);
 939
 940        if (prev && prev != root)
 941                css_put(&prev->css);
 942
 943        if (!root->use_hierarchy && root != root_mem_cgroup) {
 944                if (prev)
 945                        return NULL;
 946                return root;
 947        }
 948
 949        while (!memcg) {
 950                struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
 951                struct cgroup_subsys_state *css;
 952
 953                if (reclaim) {
 954                        int nid = zone_to_nid(reclaim->zone);
 955                        int zid = zone_idx(reclaim->zone);
 956                        struct mem_cgroup_per_zone *mz;
 957
 958                        mz = mem_cgroup_zoneinfo(root, nid, zid);
 959                        iter = &mz->reclaim_iter[reclaim->priority];
 960                        if (prev && reclaim->generation != iter->generation)
 961                                return NULL;
 962                        id = iter->position;
 963                }
 964
 965                rcu_read_lock();
 966                css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
 967                if (css) {
 968                        if (css == &root->css || css_tryget(css))
 969                                memcg = container_of(css,
 970                                                     struct mem_cgroup, css);
 971                } else
 972                        id = 0;
 973                rcu_read_unlock();
 974
 975                if (reclaim) {
 976                        iter->position = id;
 977                        if (!css)
 978                                iter->generation++;
 979                        else if (!prev && memcg)
 980                                reclaim->generation = iter->generation;
 981                }
 982
 983                if (prev && !css)
 984                        return NULL;
 985        }
 986        return memcg;
 987}
 988
 989/**
 990 * mem_cgroup_iter_break - abort a hierarchy walk prematurely
 991 * @root: hierarchy root
 992 * @prev: last visited hierarchy member as returned by mem_cgroup_iter()
 993 */
 994void mem_cgroup_iter_break(struct mem_cgroup *root,
 995                           struct mem_cgroup *prev)
 996{
 997        if (!root)
 998                root = root_mem_cgroup;
 999        if (prev && prev != root)
1000                css_put(&prev->css);
1001}
1002
1003/*
1004 * Iteration constructs for visiting all cgroups (under a tree).  If
1005 * loops are exited prematurely (break), mem_cgroup_iter_break() must
1006 * be used for reference counting.
1007 */
1008#define for_each_mem_cgroup_tree(iter, root)            \
1009        for (iter = mem_cgroup_iter(root, NULL, NULL);  \
1010             iter != NULL;                              \
1011             iter = mem_cgroup_iter(root, iter, NULL))
1012
1013#define for_each_mem_cgroup(iter)                       \
1014        for (iter = mem_cgroup_iter(NULL, NULL, NULL);  \
1015             iter != NULL;                              \
1016             iter = mem_cgroup_iter(NULL, iter, NULL))
1017
1018static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
1019{
1020        return (memcg == root_mem_cgroup);
1021}
1022
1023void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
1024{
1025        struct mem_cgroup *memcg;
1026
1027        if (!mm)
1028                return;
1029
1030        rcu_read_lock();
1031        memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
1032        if (unlikely(!memcg))
1033                goto out;
1034
1035        switch (idx) {
1036        case PGFAULT:
1037                this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
1038                break;
1039        case PGMAJFAULT:
1040                this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
1041                break;
1042        default:
1043                BUG();
1044        }
1045out:
1046        rcu_read_unlock();
1047}
1048EXPORT_SYMBOL(mem_cgroup_count_vm_event);
1049
1050/**
1051 * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
1052 * @zone: zone of the wanted lruvec
1053 * @memcg: memcg of the wanted lruvec
1054 *
1055 * Returns the lru list vector holding pages for the given @zone and
1056 * @mem.  This can be the global zone lruvec, if the memory controller
1057 * is disabled.
1058 */
1059struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
1060                                      struct mem_cgroup *memcg)
1061{
1062        struct mem_cgroup_per_zone *mz;
1063
1064        if (mem_cgroup_disabled())
1065                return &zone->lruvec;
1066
1067        mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
1068        return &mz->lruvec;
1069}
1070
1071/*
1072 * Following LRU functions are allowed to be used without PCG_LOCK.
1073 * Operations are called by routine of global LRU independently from memcg.
1074 * What we have to take care of here is validness of pc->mem_cgroup.
1075 *
1076 * Changes to pc->mem_cgroup happens when
1077 * 1. charge
1078 * 2. moving account
1079 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
1080 * It is added to LRU before charge.
1081 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
1082 * When moving account, the page is not on LRU. It's isolated.
1083 */
1084
1085/**
1086 * mem_cgroup_page_lruvec - return lruvec for adding an lru page
1087 * @page: the page
1088 * @zone: zone of the page
1089 */
1090struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
1091{
1092        struct mem_cgroup_per_zone *mz;
1093        struct mem_cgroup *memcg;
1094        struct page_cgroup *pc;
1095
1096        if (mem_cgroup_disabled())
1097                return &zone->lruvec;
1098
1099        pc = lookup_page_cgroup(page);
1100        memcg = pc->mem_cgroup;
1101
1102        /*
1103         * Surreptitiously switch any uncharged offlist page to root:
1104         * an uncharged page off lru does nothing to secure
1105         * its former mem_cgroup from sudden removal.
1106         *
1107         * Our caller holds lru_lock, and PageCgroupUsed is updated
1108         * under page_cgroup lock: between them, they make all uses
1109         * of pc->mem_cgroup safe.
1110         */
1111        if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup)
1112                pc->mem_cgroup = memcg = root_mem_cgroup;
1113
1114        mz = page_cgroup_zoneinfo(memcg, page);
1115        return &mz->lruvec;
1116}
1117
1118/**
1119 * mem_cgroup_update_lru_size - account for adding or removing an lru page
1120 * @lruvec: mem_cgroup per zone lru vector
1121 * @lru: index of lru list the page is sitting on
1122 * @nr_pages: positive when adding or negative when removing
1123 *
1124 * This function must be called when a page is added to or removed from an
1125 * lru list.
1126 */
1127void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
1128                                int nr_pages)
1129{
1130        struct mem_cgroup_per_zone *mz;
1131        unsigned long *lru_size;
1132
1133        if (mem_cgroup_disabled())
1134                return;
1135
1136        mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
1137        lru_size = mz->lru_size + lru;
1138        *lru_size += nr_pages;
1139        VM_BUG_ON((long)(*lru_size) < 0);
1140}
1141
1142/*
1143 * Checks whether given mem is same or in the root_mem_cgroup's
1144 * hierarchy subtree
1145 */
1146bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
1147                                  struct mem_cgroup *memcg)
1148{
1149        if (root_memcg == memcg)
1150                return true;
1151        if (!root_memcg->use_hierarchy || !memcg)
1152                return false;
1153        return css_is_ancestor(&memcg->css, &root_memcg->css);
1154}
1155
1156static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
1157                                       struct mem_cgroup *memcg)
1158{
1159        bool ret;
1160
1161        rcu_read_lock();
1162        ret = __mem_cgroup_same_or_subtree(root_memcg, memcg);
1163        rcu_read_unlock();
1164        return ret;
1165}
1166
1167int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
1168{
1169        int ret;
1170        struct mem_cgroup *curr = NULL;
1171        struct task_struct *p;
1172
1173        p = find_lock_task_mm(task);
1174        if (p) {
1175                curr = try_get_mem_cgroup_from_mm(p->mm);
1176                task_unlock(p);
1177        } else {
1178                /*
1179                 * All threads may have already detached their mm's, but the oom
1180                 * killer still needs to detect if they have already been oom
1181                 * killed to prevent needlessly killing additional tasks.
1182                 */
1183                task_lock(task);
1184                curr = mem_cgroup_from_task(task);
1185                if (curr)
1186                        css_get(&curr->css);
1187                task_unlock(task);
1188        }
1189        if (!curr)
1190                return 0;
1191        /*
1192         * We should check use_hierarchy of "memcg" not "curr". Because checking
1193         * use_hierarchy of "curr" here make this function true if hierarchy is
1194         * enabled in "curr" and "curr" is a child of "memcg" in *cgroup*
1195         * hierarchy(even if use_hierarchy is disabled in "memcg").
1196         */
1197        ret = mem_cgroup_same_or_subtree(memcg, curr);
1198        css_put(&curr->css);
1199        return ret;
1200}
1201
1202int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
1203{
1204        unsigned long inactive_ratio;
1205        unsigned long inactive;
1206        unsigned long active;
1207        unsigned long gb;
1208
1209        inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
1210        active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);
1211
1212        gb = (inactive + active) >> (30 - PAGE_SHIFT);
1213        if (gb)
1214                inactive_ratio = int_sqrt(10 * gb);
1215        else
1216                inactive_ratio = 1;
1217
1218        return inactive * inactive_ratio < active;
1219}
1220
1221int mem_cgroup_inactive_file_is_low(struct lruvec *lruvec)
1222{
1223        unsigned long active;
1224        unsigned long inactive;
1225
1226        inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_FILE);
1227        active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_FILE);
1228
1229        return (active > inactive);
1230}
1231
1232#define mem_cgroup_from_res_counter(counter, member)    \
1233        container_of(counter, struct mem_cgroup, member)
1234
1235/**
1236 * mem_cgroup_margin - calculate chargeable space of a memory cgroup
1237 * @memcg: the memory cgroup
1238 *
1239 * Returns the maximum amount of memory @mem can be charged with, in
1240 * pages.
1241 */
1242static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
1243{
1244        unsigned long long margin;
1245
1246        margin = res_counter_margin(&memcg->res);
1247        if (do_swap_account)
1248                margin = min(margin, res_counter_margin(&memcg->memsw));
1249        return margin >> PAGE_SHIFT;
1250}
1251
1252int mem_cgroup_swappiness(struct mem_cgroup *memcg)
1253{
1254        struct cgroup *cgrp = memcg->css.cgroup;
1255
1256        /* root ? */
1257        if (cgrp->parent == NULL)
1258                return vm_swappiness;
1259
1260        return memcg->swappiness;
1261}
1262
1263/*
1264 * memcg->moving_account is used for checking possibility that some thread is
1265 * calling move_account(). When a thread on CPU-A starts moving pages under
1266 * a memcg, other threads should check memcg->moving_account under
1267 * rcu_read_lock(), like this:
1268 *
1269 *         CPU-A                                    CPU-B
1270 *                                              rcu_read_lock()
1271 *         memcg->moving_account+1              if (memcg->mocing_account)
1272 *                                                   take heavy locks.
1273 *         synchronize_rcu()                    update something.
1274 *                                              rcu_read_unlock()
1275 *         start move here.
1276 */
1277
1278/* for quick checking without looking up memcg */
1279atomic_t memcg_moving __read_mostly;
1280
1281static void mem_cgroup_start_move(struct mem_cgroup *memcg)
1282{
1283        atomic_inc(&memcg_moving);
1284        atomic_inc(&memcg->moving_account);
1285        synchronize_rcu();
1286}
1287
1288static void mem_cgroup_end_move(struct mem_cgroup *memcg)
1289{
1290        /*
1291         * Now, mem_cgroup_clear_mc() may call this function with NULL.
1292         * We check NULL in callee rather than caller.
1293         */
1294        if (memcg) {
1295                atomic_dec(&memcg_moving);
1296                atomic_dec(&memcg->moving_account);
1297        }
1298}
1299
1300/*
1301 * 2 routines for checking "mem" is under move_account() or not.
1302 *
1303 * mem_cgroup_stolen() -  checking whether a cgroup is mc.from or not. This
1304 *                        is used for avoiding races in accounting.  If true,
1305 *                        pc->mem_cgroup may be overwritten.
1306 *
1307 * mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
1308 *                        under hierarchy of moving cgroups. This is for
1309 *                        waiting at hith-memory prressure caused by "move".
1310 */
1311
1312static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
1313{
1314        VM_BUG_ON(!rcu_read_lock_held());
1315        return atomic_read(&memcg->moving_account) > 0;
1316}
1317
1318static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
1319{
1320        struct mem_cgroup *from;
1321        struct mem_cgroup *to;
1322        bool ret = false;
1323        /*
1324         * Unlike task_move routines, we access mc.to, mc.from not under
1325         * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
1326         */
1327        spin_lock(&mc.lock);
1328        from = mc.from;
1329        to = mc.to;
1330        if (!from)
1331                goto unlock;
1332
1333        ret = mem_cgroup_same_or_subtree(memcg, from)
1334                || mem_cgroup_same_or_subtree(memcg, to);
1335unlock:
1336        spin_unlock(&mc.lock);
1337        return ret;
1338}
1339
1340static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
1341{
1342        if (mc.moving_task && current != mc.moving_task) {
1343                if (mem_cgroup_under_move(memcg)) {
1344                        DEFINE_WAIT(wait);
1345                        prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
1346                        /* moving charge context might have finished. */
1347                        if (mc.moving_task)
1348                                schedule();
1349                        finish_wait(&mc.waitq, &wait);
1350                        return true;
1351                }
1352        }
1353        return false;
1354}
1355
1356/*
1357 * Take this lock when
1358 * - a code tries to modify page's memcg while it's USED.
1359 * - a code tries to modify page state accounting in a memcg.
1360 * see mem_cgroup_stolen(), too.
1361 */
1362static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
1363                                  unsigned long *flags)
1364{
1365        spin_lock_irqsave(&memcg->move_lock, *flags);
1366}
1367
1368static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
1369                                unsigned long *flags)
1370{
1371        spin_unlock_irqrestore(&memcg->move_lock, *flags);
1372}
1373
1374/**
1375 * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
1376 * @memcg: The memory cgroup that went over limit
1377 * @p: Task that is going to be killed
1378 *
1379 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1380 * enabled
1381 */
1382void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
1383{
1384        struct cgroup *task_cgrp;
1385        struct cgroup *mem_cgrp;
1386        /*
1387         * Need a buffer in BSS, can't rely on allocations. The code relies
1388         * on the assumption that OOM is serialized for memory controller.
1389         * If this assumption is broken, revisit this code.
1390         */
1391        static char memcg_name[PATH_MAX];
1392        int ret;
1393
1394        if (!memcg || !p)
1395                return;
1396
1397        rcu_read_lock();
1398
1399        mem_cgrp = memcg->css.cgroup;
1400        task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
1401
1402        ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
1403        if (ret < 0) {
1404                /*
1405                 * Unfortunately, we are unable to convert to a useful name
1406                 * But we'll still print out the usage information
1407                 */
1408                rcu_read_unlock();
1409                goto done;
1410        }
1411        rcu_read_unlock();
1412
1413        printk(KERN_INFO "Task in %s killed", memcg_name);
1414
1415        rcu_read_lock();
1416        ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
1417        if (ret < 0) {
1418                rcu_read_unlock();
1419                goto done;
1420        }
1421        rcu_read_unlock();
1422
1423        /*
1424         * Continues from above, so we don't need an KERN_ level
1425         */
1426        printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
1427done:
1428
1429        printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
1430                res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
1431                res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
1432                res_counter_read_u64(&memcg->res, RES_FAILCNT));
1433        printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
1434                "failcnt %llu\n",
1435                res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
1436                res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
1437                res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1438}
1439
1440/*
1441 * This function returns the number of memcg under hierarchy tree. Returns
1442 * 1(self count) if no children.
1443 */
1444static int mem_cgroup_count_children(struct mem_cgroup *memcg)
1445{
1446        int num = 0;
1447        struct mem_cgroup *iter;
1448
1449        for_each_mem_cgroup_tree(iter, memcg)
1450                num++;
1451        return num;
1452}
1453
1454/*
1455 * Return the memory (and swap, if configured) limit for a memcg.
1456 */
1457u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
1458{
1459        u64 limit;
1460        u64 memsw;
1461
1462        limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
1463        limit += total_swap_pages << PAGE_SHIFT;
1464
1465        memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1466        /*
1467         * If memsw is finite and limits the amount of swap space available
1468         * to this memcg, return that limit.
1469         */
1470        return min(limit, memsw);
1471}
1472
1473static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg,
1474                                        gfp_t gfp_mask,
1475                                        unsigned long flags)
1476{
1477        unsigned long total = 0;
1478        bool noswap = false;
1479        int loop;
1480
1481        if (flags & MEM_CGROUP_RECLAIM_NOSWAP)
1482                noswap = true;
1483        if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum)
1484                noswap = true;
1485
1486        for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) {
1487                if (loop)
1488                        drain_all_stock_async(memcg);
1489                total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap);
1490                /*
1491                 * Allow limit shrinkers, which are triggered directly
1492                 * by userspace, to catch signals and stop reclaim
1493                 * after minimal progress, regardless of the margin.
1494                 */
1495                if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK))
1496                        break;
1497                if (mem_cgroup_margin(memcg))
1498                        break;
1499                /*
1500                 * If nothing was reclaimed after two attempts, there
1501                 * may be no reclaimable pages in this hierarchy.
1502                 */
1503                if (loop && !total)
1504                        break;
1505        }
1506        return total;
1507}
1508
1509/**
1510 * test_mem_cgroup_node_reclaimable
1511 * @memcg: the target memcg
1512 * @nid: the node ID to be checked.
1513 * @noswap : specify true here if the user wants flle only information.
1514 *
1515 * This function returns whether the specified memcg contains any
1516 * reclaimable pages on a node. Returns true if there are any reclaimable
1517 * pages in the node.
1518 */
1519static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
1520                int nid, bool noswap)
1521{
1522        if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
1523                return true;
1524        if (noswap || !total_swap_pages)
1525                return false;
1526        if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
1527                return true;
1528        return false;
1529
1530}
1531#if MAX_NUMNODES > 1
1532
1533/*
1534 * Always updating the nodemask is not very good - even if we have an empty
1535 * list or the wrong list here, we can start from some node and traverse all
1536 * nodes based on the zonelist. So update the list loosely once per 10 secs.
1537 *
1538 */
1539static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
1540{
1541        int nid;
1542        /*
1543         * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
1544         * pagein/pageout changes since the last update.
1545         */
1546        if (!atomic_read(&memcg->numainfo_events))
1547                return;
1548        if (atomic_inc_return(&memcg->numainfo_updating) > 1)
1549                return;
1550
1551        /* make a nodemask where this memcg uses memory from */
1552        memcg->scan_nodes = node_states[N_HIGH_MEMORY];
1553
1554        for_each_node_mask(nid, node_states[N_HIGH_MEMORY]) {
1555
1556                if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
1557                        node_clear(nid, memcg->scan_nodes);
1558        }
1559
1560        atomic_set(&memcg->numainfo_events, 0);
1561        atomic_set(&memcg->numainfo_updating, 0);
1562}
1563
1564/*
1565 * Selecting a node where we start reclaim from. Because what we need is just
1566 * reducing usage counter, start from anywhere is O,K. Considering
1567 * memory reclaim from current node, there are pros. and cons.
1568 *
1569 * Freeing memory from current node means freeing memory from a node which
1570 * we'll use or we've used. So, it may make LRU bad. And if several threads
1571 * hit limits, it will see a contention on a node. But freeing from remote
1572 * node means more costs for memory reclaim because of memory latency.
1573 *
1574 * Now, we use round-robin. Better algorithm is welcomed.
1575 */
1576int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
1577{
1578        int node;
1579
1580        mem_cgroup_may_update_nodemask(memcg);
1581        node = memcg->last_scanned_node;
1582
1583        node = next_node(node, memcg->scan_nodes);
1584        if (node == MAX_NUMNODES)
1585                node = first_node(memcg->scan_nodes);
1586        /*
1587         * We call this when we hit limit, not when pages are added to LRU.
1588         * No LRU may hold pages because all pages are UNEVICTABLE or
1589         * memcg is too small and all pages are not on LRU. In that case,
1590         * we use curret node.
1591         */
1592        if (unlikely(node == MAX_NUMNODES))
1593                node = numa_node_id();
1594
1595        memcg->last_scanned_node = node;
1596        return node;
1597}
1598
1599/*
1600 * Check all nodes whether it contains reclaimable pages or not.
1601 * For quick scan, we make use of scan_nodes. This will allow us to skip
1602 * unused nodes. But scan_nodes is lazily updated and may not cotain
1603 * enough new information. We need to do double check.
1604 */
1605static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
1606{
1607        int nid;
1608
1609        /*
1610         * quick check...making use of scan_node.
1611         * We can skip unused nodes.
1612         */
1613        if (!nodes_empty(memcg->scan_nodes)) {
1614                for (nid = first_node(memcg->scan_nodes);
1615                     nid < MAX_NUMNODES;
1616                     nid = next_node(nid, memcg->scan_nodes)) {
1617
1618                        if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
1619                                return true;
1620                }
1621        }
1622        /*
1623         * Check rest of nodes.
1624         */
1625        for_each_node_state(nid, N_HIGH_MEMORY) {
1626                if (node_isset(nid, memcg->scan_nodes))
1627                        continue;
1628                if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
1629                        return true;
1630        }
1631        return false;
1632}
1633
1634#else
1635int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
1636{
1637        return 0;
1638}
1639
1640static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
1641{
1642        return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
1643}
1644#endif
1645
1646static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
1647                                   struct zone *zone,
1648                                   gfp_t gfp_mask,
1649                                   unsigned long *total_scanned)
1650{
1651        struct mem_cgroup *victim = NULL;
1652        int total = 0;
1653        int loop = 0;
1654        unsigned long excess;
1655        unsigned long nr_scanned;
1656        struct mem_cgroup_reclaim_cookie reclaim = {
1657                .zone = zone,
1658                .priority = 0,
1659        };
1660
1661        excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
1662
1663        while (1) {
1664                victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
1665                if (!victim) {
1666                        loop++;
1667                        if (loop >= 2) {
1668                                /*
1669                                 * If we have not been able to reclaim
1670                                 * anything, it might because there are
1671                                 * no reclaimable pages under this hierarchy
1672                                 */
1673                                if (!total)
1674                                        break;
1675                                /*
1676                                 * We want to do more targeted reclaim.
1677                                 * excess >> 2 is not to excessive so as to
1678                                 * reclaim too much, nor too less that we keep
1679                                 * coming back to reclaim from this cgroup
1680                                 */
1681                                if (total >= (excess >> 2) ||
1682                                        (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
1683                                        break;
1684                        }
1685                        continue;
1686                }
1687                if (!mem_cgroup_reclaimable(victim, false))
1688                        continue;
1689                total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
1690                                                     zone, &nr_scanned);
1691                *total_scanned += nr_scanned;
1692                if (!res_counter_soft_limit_excess(&root_memcg->res))
1693                        break;
1694        }
1695        mem_cgroup_iter_break(root_memcg, victim);
1696        return total;
1697}
1698
1699/*
1700 * Check OOM-Killer is already running under our hierarchy.
1701 * If someone is running, return false.
1702 * Has to be called with memcg_oom_lock
1703 */
1704static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg)
1705{
1706        struct mem_cgroup *iter, *failed = NULL;
1707
1708        for_each_mem_cgroup_tree(iter, memcg) {
1709                if (iter->oom_lock) {
1710                        /*
1711                         * this subtree of our hierarchy is already locked
1712                         * so we cannot give a lock.
1713                         */
1714                        failed = iter;
1715                        mem_cgroup_iter_break(memcg, iter);
1716                        break;
1717                } else
1718                        iter->oom_lock = true;
1719        }
1720
1721        if (!failed)
1722                return true;
1723
1724        /*
1725         * OK, we failed to lock the whole subtree so we have to clean up
1726         * what we set up to the failing subtree
1727         */
1728        for_each_mem_cgroup_tree(iter, memcg) {
1729                if (iter == failed) {
1730                        mem_cgroup_iter_break(memcg, iter);
1731                        break;
1732                }
1733                iter->oom_lock = false;
1734        }
1735        return false;
1736}
1737
1738/*
1739 * Has to be called with memcg_oom_lock
1740 */
1741static int mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
1742{
1743        struct mem_cgroup *iter;
1744
1745        for_each_mem_cgroup_tree(iter, memcg)
1746                iter->oom_lock = false;
1747        return 0;
1748}
1749
1750static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
1751{
1752        struct mem_cgroup *iter;
1753
1754        for_each_mem_cgroup_tree(iter, memcg)
1755                atomic_inc(&iter->under_oom);
1756}
1757
1758static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
1759{
1760        struct mem_cgroup *iter;
1761
1762        /*
1763         * When a new child is created while the hierarchy is under oom,
1764         * mem_cgroup_oom_lock() may not be called. We have to use
1765         * atomic_add_unless() here.
1766         */
1767        for_each_mem_cgroup_tree(iter, memcg)
1768                atomic_add_unless(&iter->under_oom, -1, 0);
1769}
1770
1771static DEFINE_SPINLOCK(memcg_oom_lock);
1772static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1773
1774struct oom_wait_info {
1775        struct mem_cgroup *memcg;
1776        wait_queue_t    wait;
1777};
1778
1779static int memcg_oom_wake_function(wait_queue_t *wait,
1780        unsigned mode, int sync, void *arg)
1781{
1782        struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
1783        struct mem_cgroup *oom_wait_memcg;
1784        struct oom_wait_info *oom_wait_info;
1785
1786        oom_wait_info = container_of(wait, struct oom_wait_info, wait);
1787        oom_wait_memcg = oom_wait_info->memcg;
1788
1789        /*
1790         * Both of oom_wait_info->memcg and wake_memcg are stable under us.
1791         * Then we can use css_is_ancestor without taking care of RCU.
1792         */
1793        if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg)
1794                && !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg))
1795                return 0;
1796        return autoremove_wake_function(wait, mode, sync, arg);
1797}
1798
1799static void memcg_wakeup_oom(struct mem_cgroup *memcg)
1800{
1801        /* for filtering, pass "memcg" as argument. */
1802        __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
1803}
1804
1805static void memcg_oom_recover(struct mem_cgroup *memcg)
1806{
1807        if (memcg && atomic_read(&memcg->under_oom))
1808                memcg_wakeup_oom(memcg);
1809}
1810
1811/*
1812 * try to call OOM killer. returns false if we should exit memory-reclaim loop.
1813 */
1814static bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask,
1815                                  int order)
1816{
1817        struct oom_wait_info owait;
1818        bool locked, need_to_kill;
1819
1820        owait.memcg = memcg;
1821        owait.wait.flags = 0;
1822        owait.wait.func = memcg_oom_wake_function;
1823        owait.wait.private = current;
1824        INIT_LIST_HEAD(&owait.wait.task_list);
1825        need_to_kill = true;
1826        mem_cgroup_mark_under_oom(memcg);
1827
1828        /* At first, try to OOM lock hierarchy under memcg.*/
1829        spin_lock(&memcg_oom_lock);
1830        locked = mem_cgroup_oom_lock(memcg);
1831        /*
1832         * Even if signal_pending(), we can't quit charge() loop without
1833         * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
1834         * under OOM is always welcomed, use TASK_KILLABLE here.
1835         */
1836        prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
1837        if (!locked || memcg->oom_kill_disable)
1838                need_to_kill = false;
1839        if (locked)
1840                mem_cgroup_oom_notify(memcg);
1841        spin_unlock(&memcg_oom_lock);
1842
1843        if (need_to_kill) {
1844                finish_wait(&memcg_oom_waitq, &owait.wait);
1845                mem_cgroup_out_of_memory(memcg, mask, order);
1846        } else {
1847                schedule();
1848                finish_wait(&memcg_oom_waitq, &owait.wait);
1849        }
1850        spin_lock(&memcg_oom_lock);
1851        if (locked)
1852                mem_cgroup_oom_unlock(memcg);
1853        memcg_wakeup_oom(memcg);
1854        spin_unlock(&memcg_oom_lock);
1855
1856        mem_cgroup_unmark_under_oom(memcg);
1857
1858        if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
1859                return false;
1860        /* Give chance to dying process */
1861        schedule_timeout_uninterruptible(1);
1862        return true;
1863}
1864
1865/*
1866 * Currently used to update mapped file statistics, but the routine can be
1867 * generalized to update other statistics as well.
1868 *
1869 * Notes: Race condition
1870 *
1871 * We usually use page_cgroup_lock() for accessing page_cgroup member but
1872 * it tends to be costly. But considering some conditions, we doesn't need
1873 * to do so _always_.
1874 *
1875 * Considering "charge", lock_page_cgroup() is not required because all
1876 * file-stat operations happen after a page is attached to radix-tree. There
1877 * are no race with "charge".
1878 *
1879 * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
1880 * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
1881 * if there are race with "uncharge". Statistics itself is properly handled
1882 * by flags.
1883 *
1884 * Considering "move", this is an only case we see a race. To make the race
1885 * small, we check mm->moving_account and detect there are possibility of race
1886 * If there is, we take a lock.
1887 */
1888
1889void __mem_cgroup_begin_update_page_stat(struct page *page,
1890                                bool *locked, unsigned long *flags)
1891{
1892        struct mem_cgroup *memcg;
1893        struct page_cgroup *pc;
1894
1895        pc = lookup_page_cgroup(page);
1896again:
1897        memcg = pc->mem_cgroup;
1898        if (unlikely(!memcg || !PageCgroupUsed(pc)))
1899                return;
1900        /*
1901         * If this memory cgroup is not under account moving, we don't
1902         * need to take move_lock_page_cgroup(). Because we already hold
1903         * rcu_read_lock(), any calls to move_account will be delayed until
1904         * rcu_read_unlock() if mem_cgroup_stolen() == true.
1905         */
1906        if (!mem_cgroup_stolen(memcg))
1907                return;
1908
1909        move_lock_mem_cgroup(memcg, flags);
1910        if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
1911                move_unlock_mem_cgroup(memcg, flags);
1912                goto again;
1913        }
1914        *locked = true;
1915}
1916
1917void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
1918{
1919        struct page_cgroup *pc = lookup_page_cgroup(page);
1920
1921        /*
1922         * It's guaranteed that pc->mem_cgroup never changes while
1923         * lock is held because a routine modifies pc->mem_cgroup
1924         * should take move_lock_page_cgroup().
1925         */
1926        move_unlock_mem_cgroup(pc->mem_cgroup, flags);
1927}
1928
1929void mem_cgroup_update_page_stat(struct page *page,
1930                                 enum mem_cgroup_page_stat_item idx, int val)
1931{
1932        struct mem_cgroup *memcg;
1933        struct page_cgroup *pc = lookup_page_cgroup(page);
1934        unsigned long uninitialized_var(flags);
1935
1936        if (mem_cgroup_disabled())
1937                return;
1938
1939        memcg = pc->mem_cgroup;
1940        if (unlikely(!memcg || !PageCgroupUsed(pc)))
1941                return;
1942
1943        switch (idx) {
1944        case MEMCG_NR_FILE_MAPPED:
1945                idx = MEM_CGROUP_STAT_FILE_MAPPED;
1946                break;
1947        default:
1948                BUG();
1949        }
1950
1951        this_cpu_add(memcg->stat->count[idx], val);
1952}
1953
1954/*
1955 * size of first charge trial. "32" comes from vmscan.c's magic value.
1956 * TODO: maybe necessary to use big numbers in big irons.
1957 */
1958#define CHARGE_BATCH    32U
1959struct memcg_stock_pcp {
1960        struct mem_cgroup *cached; /* this never be root cgroup */
1961        unsigned int nr_pages;
1962        struct work_struct work;
1963        unsigned long flags;
1964#define FLUSHING_CACHED_CHARGE  0
1965};
1966static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
1967static DEFINE_MUTEX(percpu_charge_mutex);
1968
1969/*
1970 * Try to consume stocked charge on this cpu. If success, one page is consumed
1971 * from local stock and true is returned. If the stock is 0 or charges from a
1972 * cgroup which is not current target, returns false. This stock will be
1973 * refilled.
1974 */
1975static bool consume_stock(struct mem_cgroup *memcg)
1976{
1977        struct memcg_stock_pcp *stock;
1978        bool ret = true;
1979
1980        stock = &get_cpu_var(memcg_stock);
1981        if (memcg == stock->cached && stock->nr_pages)
1982                stock->nr_pages--;
1983        else /* need to call res_counter_charge */
1984                ret = false;
1985        put_cpu_var(memcg_stock);
1986        return ret;
1987}
1988
1989/*
1990 * Returns stocks cached in percpu to res_counter and reset cached information.
1991 */
1992static void drain_stock(struct memcg_stock_pcp *stock)
1993{
1994        struct mem_cgroup *old = stock->cached;
1995
1996        if (stock->nr_pages) {
1997                unsigned long bytes = stock->nr_pages * PAGE_SIZE;
1998
1999                res_counter_uncharge(&old->res, bytes);
2000                if (do_swap_account)
2001                        res_counter_uncharge(&old->memsw, bytes);
2002                stock->nr_pages = 0;
2003        }
2004        stock->cached = NULL;
2005}
2006
2007/*
2008 * This must be called under preempt disabled or must be called by
2009 * a thread which is pinned to local cpu.
2010 */
2011static void drain_local_stock(struct work_struct *dummy)
2012{
2013        struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
2014        drain_stock(stock);
2015        clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
2016}
2017
2018/*
2019 * Cache charges(val) which is from res_counter, to local per_cpu area.
2020 * This will be consumed by consume_stock() function, later.
2021 */
2022static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2023{
2024        struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
2025
2026        if (stock->cached != memcg) { /* reset if necessary */
2027                drain_stock(stock);
2028                stock->cached = memcg;
2029        }
2030        stock->nr_pages += nr_pages;
2031        put_cpu_var(memcg_stock);
2032}
2033
2034/*
2035 * Drains all per-CPU charge caches for given root_memcg resp. subtree
2036 * of the hierarchy under it. sync flag says whether we should block
2037 * until the work is done.
2038 */
2039static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
2040{
2041        int cpu, curcpu;
2042
2043        /* Notify other cpus that system-wide "drain" is running */
2044        get_online_cpus();
2045        curcpu = get_cpu();
2046        for_each_online_cpu(cpu) {
2047                struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2048                struct mem_cgroup *memcg;
2049
2050                memcg = stock->cached;
2051                if (!memcg || !stock->nr_pages)
2052                        continue;
2053                if (!mem_cgroup_same_or_subtree(root_memcg, memcg))
2054                        continue;
2055                if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
2056                        if (cpu == curcpu)
2057                                drain_local_stock(&stock->work);
2058                        else
2059                                schedule_work_on(cpu, &stock->work);
2060                }
2061        }
2062        put_cpu();
2063
2064        if (!sync)
2065                goto out;
2066
2067        for_each_online_cpu(cpu) {
2068                struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2069                if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
2070                        flush_work(&stock->work);
2071        }
2072out:
2073        put_online_cpus();
2074}
2075
2076/*
2077 * Tries to drain stocked charges in other cpus. This function is asynchronous
2078 * and just put a work per cpu for draining localy on each cpu. Caller can
2079 * expects some charges will be back to res_counter later but cannot wait for
2080 * it.
2081 */
2082static void drain_all_stock_async(struct mem_cgroup *root_memcg)
2083{
2084        /*
2085         * If someone calls draining, avoid adding more kworker runs.
2086         */
2087        if (!mutex_trylock(&percpu_charge_mutex))
2088                return;
2089        drain_all_stock(root_memcg, false);
2090        mutex_unlock(&percpu_charge_mutex);
2091}
2092
2093/* This is a synchronous drain interface. */
2094static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
2095{
2096        /* called when force_empty is called */
2097        mutex_lock(&percpu_charge_mutex);
2098        drain_all_stock(root_memcg, true);
2099        mutex_unlock(&percpu_charge_mutex);
2100}
2101
2102/*
2103 * This function drains percpu counter value from DEAD cpu and
2104 * move it to local cpu. Note that this function can be preempted.
2105 */
2106static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu)
2107{
2108        int i;
2109
2110        spin_lock(&memcg->pcp_counter_lock);
2111        for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
2112                long x = per_cpu(memcg->stat->count[i], cpu);
2113
2114                per_cpu(memcg->stat->count[i], cpu) = 0;
2115                memcg->nocpu_base.count[i] += x;
2116        }
2117        for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
2118                unsigned long x = per_cpu(memcg->stat->events[i], cpu);
2119
2120                per_cpu(memcg->stat->events[i], cpu) = 0;
2121                memcg->nocpu_base.events[i] += x;
2122        }
2123        spin_unlock(&memcg->pcp_counter_lock);
2124}
2125
2126static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb,
2127                                        unsigned long action,
2128                                        void *hcpu)
2129{
2130        int cpu = (unsigned long)hcpu;
2131        struct memcg_stock_pcp *stock;
2132        struct mem_cgroup *iter;
2133
2134        if (action == CPU_ONLINE)
2135                return NOTIFY_OK;
2136
2137        if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
2138                return NOTIFY_OK;
2139
2140        for_each_mem_cgroup(iter)
2141                mem_cgroup_drain_pcp_counter(iter, cpu);
2142
2143        stock = &per_cpu(memcg_stock, cpu);
2144        drain_stock(stock);
2145        return NOTIFY_OK;
2146}
2147
2148
2149/* See __mem_cgroup_try_charge() for details */
2150enum {
2151        CHARGE_OK,              /* success */
2152        CHARGE_RETRY,           /* need to retry but retry is not bad */
2153        CHARGE_NOMEM,           /* we can't do more. return -ENOMEM */
2154        CHARGE_WOULDBLOCK,      /* GFP_WAIT wasn't set and no enough res. */
2155        CHARGE_OOM_DIE,         /* the current is killed because of OOM */
2156};
2157
2158static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
2159                                unsigned int nr_pages, bool oom_check)
2160{
2161        unsigned long csize = nr_pages * PAGE_SIZE;
2162        struct mem_cgroup *mem_over_limit;
2163        struct res_counter *fail_res;
2164        unsigned long flags = 0;
2165        int ret;
2166
2167        ret = res_counter_charge(&memcg->res, csize, &fail_res);
2168
2169        if (likely(!ret)) {
2170                if (!do_swap_account)
2171                        return CHARGE_OK;
2172                ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
2173                if (likely(!ret))
2174                        return CHARGE_OK;
2175
2176                res_counter_uncharge(&memcg->res, csize);
2177                mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
2178                flags |= MEM_CGROUP_RECLAIM_NOSWAP;
2179        } else
2180                mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
2181        /*
2182         * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch
2183         * of regular pages (CHARGE_BATCH), or a single regular page (1).
2184         *
2185         * Never reclaim on behalf of optional batching, retry with a
2186         * single page instead.
2187         */
2188        if (nr_pages == CHARGE_BATCH)
2189                return CHARGE_RETRY;
2190
2191        if (!(gfp_mask & __GFP_WAIT))
2192                return CHARGE_WOULDBLOCK;
2193
2194        ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
2195        if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
2196                return CHARGE_RETRY;
2197        /*
2198         * Even though the limit is exceeded at this point, reclaim
2199         * may have been able to free some pages.  Retry the charge
2200         * before killing the task.
2201         *
2202         * Only for regular pages, though: huge pages are rather
2203         * unlikely to succeed so close to the limit, and we fall back
2204         * to regular pages anyway in case of failure.
2205         */
2206        if (nr_pages == 1 && ret)
2207                return CHARGE_RETRY;
2208
2209        /*
2210         * At task move, charge accounts can be doubly counted. So, it's
2211         * better to wait until the end of task_move if something is going on.
2212         */
2213        if (mem_cgroup_wait_acct_move(mem_over_limit))
2214                return CHARGE_RETRY;
2215
2216        /* If we don't need to call oom-killer at el, return immediately */
2217        if (!oom_check)
2218                return CHARGE_NOMEM;
2219        /* check OOM */
2220        if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize)))
2221                return CHARGE_OOM_DIE;
2222
2223        return CHARGE_RETRY;
2224}
2225
2226/*
2227 * __mem_cgroup_try_charge() does
2228 * 1. detect memcg to be charged against from passed *mm and *ptr,
2229 * 2. update res_counter
2230 * 3. call memory reclaim if necessary.
2231 *
2232 * In some special case, if the task is fatal, fatal_signal_pending() or
2233 * has TIF_MEMDIE, this function returns -EINTR while writing root_mem_cgroup
2234 * to *ptr. There are two reasons for this. 1: fatal threads should quit as soon
2235 * as possible without any hazards. 2: all pages should have a valid
2236 * pc->mem_cgroup. If mm is NULL and the caller doesn't pass a valid memcg
2237 * pointer, that is treated as a charge to root_mem_cgroup.
2238 *
2239 * So __mem_cgroup_try_charge() will return
2240 *  0       ...  on success, filling *ptr with a valid memcg pointer.
2241 *  -ENOMEM ...  charge failure because of resource limits.
2242 *  -EINTR  ...  if thread is fatal. *ptr is filled with root_mem_cgroup.
2243 *
2244 * Unlike the exported interface, an "oom" parameter is added. if oom==true,
2245 * the oom-killer can be invoked.
2246 */
2247static int __mem_cgroup_try_charge(struct mm_struct *mm,
2248                                   gfp_t gfp_mask,
2249                                   unsigned int nr_pages,
2250                                   struct mem_cgroup **ptr,
2251                                   bool oom)
2252{
2253        unsigned int batch = max(CHARGE_BATCH, nr_pages);
2254        int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
2255        struct mem_cgroup *memcg = NULL;
2256        int ret;
2257
2258        /*
2259         * Unlike gloval-vm's OOM-kill, we're not in memory shortage
2260         * in system level. So, allow to go ahead dying process in addition to
2261         * MEMDIE process.
2262         */
2263        if (unlikely(test_thread_flag(TIF_MEMDIE)
2264                     || fatal_signal_pending(current)))
2265                goto bypass;
2266
2267        /*
2268         * We always charge the cgroup the mm_struct belongs to.
2269         * The mm_struct's mem_cgroup changes on task migration if the
2270         * thread group leader migrates. It's possible that mm is not
2271         * set, if so charge the init_mm (happens for pagecache usage).
2272         */
2273        if (!*ptr && !mm)
2274                *ptr = root_mem_cgroup;
2275again:
2276        if (*ptr) { /* css should be a valid one */
2277                memcg = *ptr;
2278                VM_BUG_ON(css_is_removed(&memcg->css));
2279                if (mem_cgroup_is_root(memcg))
2280                        goto done;
2281                if (nr_pages == 1 && consume_stock(memcg))
2282                        goto done;
2283                css_get(&memcg->css);
2284        } else {
2285                struct task_struct *p;
2286
2287                rcu_read_lock();
2288                p = rcu_dereference(mm->owner);
2289                /*
2290                 * Because we don't have task_lock(), "p" can exit.
2291                 * In that case, "memcg" can point to root or p can be NULL with
2292                 * race with swapoff. Then, we have small risk of mis-accouning.
2293                 * But such kind of mis-account by race always happens because
2294                 * we don't have cgroup_mutex(). It's overkill and we allo that
2295                 * small race, here.
2296                 * (*) swapoff at el will charge against mm-struct not against
2297                 * task-struct. So, mm->owner can be NULL.
2298                 */
2299                memcg = mem_cgroup_from_task(p);
2300                if (!memcg)
2301                        memcg = root_mem_cgroup;
2302                if (mem_cgroup_is_root(memcg)) {
2303                        rcu_read_unlock();
2304                        goto done;
2305                }
2306                if (nr_pages == 1 && consume_stock(memcg)) {
2307                        /*
2308                         * It seems dagerous to access memcg without css_get().
2309                         * But considering how consume_stok works, it's not
2310                         * necessary. If consume_stock success, some charges
2311                         * from this memcg are cached on this cpu. So, we
2312                         * don't need to call css_get()/css_tryget() before
2313                         * calling consume_stock().
2314                         */
2315                        rcu_read_unlock();
2316                        goto done;
2317                }
2318                /* after here, we may be blocked. we need to get refcnt */
2319                if (!css_tryget(&memcg->css)) {
2320                        rcu_read_unlock();
2321                        goto again;
2322                }
2323                rcu_read_unlock();
2324        }
2325
2326        do {
2327                bool oom_check;
2328
2329                /* If killed, bypass charge */
2330                if (fatal_signal_pending(current)) {
2331                        css_put(&memcg->css);
2332                        goto bypass;
2333                }
2334
2335                oom_check = false;
2336                if (oom && !nr_oom_retries) {
2337                        oom_check = true;
2338                        nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
2339                }
2340
2341                ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check);
2342                switch (ret) {
2343                case CHARGE_OK:
2344                        break;
2345                case CHARGE_RETRY: /* not in OOM situation but retry */
2346                        batch = nr_pages;
2347                        css_put(&memcg->css);
2348                        memcg = NULL;
2349                        goto again;
2350                case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
2351                        css_put(&memcg->css);
2352                        goto nomem;
2353                case CHARGE_NOMEM: /* OOM routine works */
2354                        if (!oom) {
2355                                css_put(&memcg->css);
2356                                goto nomem;
2357                        }
2358                        /* If oom, we never return -ENOMEM */
2359                        nr_oom_retries--;
2360                        break;
2361                case CHARGE_OOM_DIE: /* Killed by OOM Killer */
2362                        css_put(&memcg->css);
2363                        goto bypass;
2364                }
2365        } while (ret != CHARGE_OK);
2366
2367        if (batch > nr_pages)
2368                refill_stock(memcg, batch - nr_pages);
2369        css_put(&memcg->css);
2370done:
2371        *ptr = memcg;
2372        return 0;
2373nomem:
2374        *ptr = NULL;
2375        return -ENOMEM;
2376bypass:
2377        *ptr = root_mem_cgroup;
2378        return -EINTR;
2379}
2380
2381/*
2382 * Somemtimes we have to undo a charge we got by try_charge().
2383 * This function is for that and do uncharge, put css's refcnt.
2384 * gotten by try_charge().
2385 */
2386static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
2387                                       unsigned int nr_pages)
2388{
2389        if (!mem_cgroup_is_root(memcg)) {
2390                unsigned long bytes = nr_pages * PAGE_SIZE;
2391
2392                res_counter_uncharge(&memcg->res, bytes);
2393                if (do_swap_account)
2394                        res_counter_uncharge(&memcg->memsw, bytes);
2395        }
2396}
2397
2398/*
2399 * Cancel chrages in this cgroup....doesn't propagate to parent cgroup.
2400 * This is useful when moving usage to parent cgroup.
2401 */
2402static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
2403                                        unsigned int nr_pages)
2404{
2405        unsigned long bytes = nr_pages * PAGE_SIZE;
2406
2407        if (mem_cgroup_is_root(memcg))
2408                return;
2409
2410        res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
2411        if (do_swap_account)
2412                res_counter_uncharge_until(&memcg->memsw,
2413                                                memcg->memsw.parent, bytes);
2414}
2415
2416/*
2417 * A helper function to get mem_cgroup from ID. must be called under
2418 * rcu_read_lock(). The caller must check css_is_removed() or some if
2419 * it's concern. (dropping refcnt from swap can be called against removed
2420 * memcg.)
2421 */
2422static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
2423{
2424        struct cgroup_subsys_state *css;
2425
2426        /* ID 0 is unused ID */
2427        if (!id)
2428                return NULL;
2429        css = css_lookup(&mem_cgroup_subsys, id);
2430        if (!css)
2431                return NULL;
2432        return container_of(css, struct mem_cgroup, css);
2433}
2434
2435struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
2436{
2437        struct mem_cgroup *memcg = NULL;
2438        struct page_cgroup *pc;
2439        unsigned short id;
2440        swp_entry_t ent;
2441
2442        VM_BUG_ON(!PageLocked(page));
2443
2444        pc = lookup_page_cgroup(page);
2445        lock_page_cgroup(pc);
2446        if (PageCgroupUsed(pc)) {
2447                memcg = pc->mem_cgroup;
2448                if (memcg && !css_tryget(&memcg->css))
2449                        memcg = NULL;
2450        } else if (PageSwapCache(page)) {
2451                ent.val = page_private(page);
2452                id = lookup_swap_cgroup_id(ent);
2453                rcu_read_lock();
2454                memcg = mem_cgroup_lookup(id);
2455                if (memcg && !css_tryget(&memcg->css))
2456                        memcg = NULL;
2457                rcu_read_unlock();
2458        }
2459        unlock_page_cgroup(pc);
2460        return memcg;
2461}
2462
2463static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
2464                                       struct page *page,
2465                                       unsigned int nr_pages,
2466                                       enum charge_type ctype,
2467                                       bool lrucare)
2468{
2469        struct page_cgroup *pc = lookup_page_cgroup(page);
2470        struct zone *uninitialized_var(zone);
2471        struct lruvec *lruvec;
2472        bool was_on_lru = false;
2473        bool anon;
2474
2475        lock_page_cgroup(pc);
2476        if (unlikely(PageCgroupUsed(pc))) {
2477                unlock_page_cgroup(pc);
2478                __mem_cgroup_cancel_charge(memcg, nr_pages);
2479                return;
2480        }
2481        /*
2482         * we don't need page_cgroup_lock about tail pages, becase they are not
2483         * accessed by any other context at this point.
2484         */
2485
2486        /*
2487         * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
2488         * may already be on some other mem_cgroup's LRU.  Take care of it.
2489         */
2490        if (lrucare) {
2491                zone = page_zone(page);
2492                spin_lock_irq(&zone->lru_lock);
2493                if (PageLRU(page)) {
2494                        lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2495                        ClearPageLRU(page);
2496                        del_page_from_lru_list(page, lruvec, page_lru(page));
2497                        was_on_lru = true;
2498                }
2499        }
2500
2501        pc->mem_cgroup = memcg;
2502        /*
2503         * We access a page_cgroup asynchronously without lock_page_cgroup().
2504         * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
2505         * is accessed after testing USED bit. To make pc->mem_cgroup visible
2506         * before USED bit, we need memory barrier here.
2507         * See mem_cgroup_add_lru_list(), etc.
2508         */
2509        smp_wmb();
2510        SetPageCgroupUsed(pc);
2511
2512        if (lrucare) {
2513                if (was_on_lru) {
2514                        lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2515                        VM_BUG_ON(PageLRU(page));
2516                        SetPageLRU(page);
2517                        add_page_to_lru_list(page, lruvec, page_lru(page));
2518                }
2519                spin_unlock_irq(&zone->lru_lock);
2520        }
2521
2522        if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
2523                anon = true;
2524        else
2525                anon = false;
2526
2527        mem_cgroup_charge_statistics(memcg, anon, nr_pages);
2528        unlock_page_cgroup(pc);
2529
2530        /*
2531         * "charge_statistics" updated event counter. Then, check it.
2532         * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
2533         * if they exceeds softlimit.
2534         */
2535        memcg_check_events(memcg, page);
2536}
2537
2538#ifdef CONFIG_TRANSPARENT_HUGEPAGE
2539
2540#define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION)
2541/*
2542 * Because tail pages are not marked as "used", set it. We're under
2543 * zone->lru_lock, 'splitting on pmd' and compound_lock.
2544 * charge/uncharge will be never happen and move_account() is done under
2545 * compound_lock(), so we don't have to take care of races.
2546 */
2547void mem_cgroup_split_huge_fixup(struct page *head)
2548{
2549        struct page_cgroup *head_pc = lookup_page_cgroup(head);
2550        struct page_cgroup *pc;
2551        int i;
2552
2553        if (mem_cgroup_disabled())
2554                return;
2555        for (i = 1; i < HPAGE_PMD_NR; i++) {
2556                pc = head_pc + i;
2557                pc->mem_cgroup = head_pc->mem_cgroup;
2558                smp_wmb();/* see __commit_charge() */
2559                pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
2560        }
2561}
2562#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
2563
2564/**
2565 * mem_cgroup_move_account - move account of the page
2566 * @page: the page
2567 * @nr_pages: number of regular pages (>1 for huge pages)
2568 * @pc: page_cgroup of the page.
2569 * @from: mem_cgroup which the page is moved from.
2570 * @to: mem_cgroup which the page is moved to. @from != @to.
2571 *
2572 * The caller must confirm following.
2573 * - page is not on LRU (isolate_page() is useful.)
2574 * - compound_lock is held when nr_pages > 1
2575 *
2576 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
2577 * from old cgroup.
2578 */
2579static int mem_cgroup_move_account(struct page *page,
2580                                   unsigned int nr_pages,
2581                                   struct page_cgroup *pc,
2582                                   struct mem_cgroup *from,
2583                                   struct mem_cgroup *to)
2584{
2585        unsigned long flags;
2586        int ret;
2587        bool anon = PageAnon(page);
2588
2589        VM_BUG_ON(from == to);
2590        VM_BUG_ON(PageLRU(page));
2591        /*
2592         * The page is isolated from LRU. So, collapse function
2593         * will not handle this page. But page splitting can happen.
2594         * Do this check under compound_page_lock(). The caller should
2595         * hold it.
2596         */
2597        ret = -EBUSY;
2598        if (nr_pages > 1 && !PageTransHuge(page))
2599                goto out;
2600
2601        lock_page_cgroup(pc);
2602
2603        ret = -EINVAL;
2604        if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
2605                goto unlock;
2606
2607        move_lock_mem_cgroup(from, &flags);
2608
2609        if (!anon && page_mapped(page)) {
2610                /* Update mapped_file data for mem_cgroup */
2611                preempt_disable();
2612                __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
2613                __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
2614                preempt_enable();
2615        }
2616        mem_cgroup_charge_statistics(from, anon, -nr_pages);
2617
2618        /* caller should have done css_get */
2619        pc->mem_cgroup = to;
2620        mem_cgroup_charge_statistics(to, anon, nr_pages);
2621        /*
2622         * We charges against "to" which may not have any tasks. Then, "to"
2623         * can be under rmdir(). But in current implementation, caller of
2624         * this function is just force_empty() and move charge, so it's
2625         * guaranteed that "to" is never removed. So, we don't check rmdir
2626         * status here.
2627         */
2628        move_unlock_mem_cgroup(from, &flags);
2629        ret = 0;
2630unlock:
2631        unlock_page_cgroup(pc);
2632        /*
2633         * check events
2634         */
2635        memcg_check_events(to, page);
2636        memcg_check_events(from, page);
2637out:
2638        return ret;
2639}
2640
2641/*
2642 * move charges to its parent.
2643 */
2644
2645static int mem_cgroup_move_parent(struct page *page,
2646                                  struct page_cgroup *pc,
2647                                  struct mem_cgroup *child,
2648                                  gfp_t gfp_mask)
2649{
2650        struct mem_cgroup *parent;
2651        unsigned int nr_pages;
2652        unsigned long uninitialized_var(flags);
2653        int ret;
2654
2655        /* Is ROOT ? */
2656        if (mem_cgroup_is_root(child))
2657                return -EINVAL;
2658
2659        ret = -EBUSY;
2660        if (!get_page_unless_zero(page))
2661                goto out;
2662        if (isolate_lru_page(page))
2663                goto put;
2664
2665        nr_pages = hpage_nr_pages(page);
2666
2667        parent = parent_mem_cgroup(child);
2668        /*
2669         * If no parent, move charges to root cgroup.
2670         */
2671        if (!parent)
2672                parent = root_mem_cgroup;
2673
2674        if (nr_pages > 1)
2675                flags = compound_lock_irqsave(page);
2676
2677        ret = mem_cgroup_move_account(page, nr_pages,
2678                                pc, child, parent);
2679        if (!ret)
2680                __mem_cgroup_cancel_local_charge(child, nr_pages);
2681
2682        if (nr_pages > 1)
2683                compound_unlock_irqrestore(page, flags);
2684        putback_lru_page(page);
2685put:
2686        put_page(page);
2687out:
2688        return ret;
2689}
2690
2691/*
2692 * Charge the memory controller for page usage.
2693 * Return
2694 * 0 if the charge was successful
2695 * < 0 if the cgroup is over its limit
2696 */
2697static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
2698                                gfp_t gfp_mask, enum charge_type ctype)
2699{
2700        struct mem_cgroup *memcg = NULL;
2701        unsigned int nr_pages = 1;
2702        bool oom = true;
2703        int ret;
2704
2705        if (PageTransHuge(page)) {
2706                nr_pages <<= compound_order(page);
2707                VM_BUG_ON(!PageTransHuge(page));
2708                /*
2709                 * Never OOM-kill a process for a huge page.  The
2710                 * fault handler will fall back to regular pages.
2711                 */
2712                oom = false;
2713        }
2714
2715        ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
2716        if (ret == -ENOMEM)
2717                return ret;
2718        __mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false);
2719        return 0;
2720}
2721
2722int mem_cgroup_newpage_charge(struct page *page,
2723                              struct mm_struct *mm, gfp_t gfp_mask)
2724{
2725        if (mem_cgroup_disabled())
2726                return 0;
2727        VM_BUG_ON(page_mapped(page));
2728        VM_BUG_ON(page->mapping && !PageAnon(page));
2729        VM_BUG_ON(!mm);
2730        return mem_cgroup_charge_common(page, mm, gfp_mask,
2731                                        MEM_CGROUP_CHARGE_TYPE_MAPPED);
2732}
2733
2734static void
2735__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
2736                                        enum charge_type ctype);
2737
2738int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
2739                                gfp_t gfp_mask)
2740{
2741        struct mem_cgroup *memcg = NULL;
2742        enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
2743        int ret;
2744
2745        if (mem_cgroup_disabled())
2746                return 0;
2747        if (PageCompound(page))
2748                return 0;
2749
2750        if (unlikely(!mm))
2751                mm = &init_mm;
2752        if (!page_is_file_cache(page))
2753                type = MEM_CGROUP_CHARGE_TYPE_SHMEM;
2754
2755        if (!PageSwapCache(page))
2756                ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);
2757        else { /* page is swapcache/shmem */
2758                ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &memcg);
2759                if (!ret)
2760                        __mem_cgroup_commit_charge_swapin(page, memcg, type);
2761        }
2762        return ret;
2763}
2764
2765/*
2766 * While swap-in, try_charge -> commit or cancel, the page is locked.
2767 * And when try_charge() successfully returns, one refcnt to memcg without
2768 * struct page_cgroup is acquired. This refcnt will be consumed by
2769 * "commit()" or removed by "cancel()"
2770 */
2771int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
2772                                 struct page *page,
2773                                 gfp_t mask, struct mem_cgroup **memcgp)
2774{
2775        struct mem_cgroup *memcg;
2776        int ret;
2777
2778        *memcgp = NULL;
2779
2780        if (mem_cgroup_disabled())
2781                return 0;
2782
2783        if (!do_swap_account)
2784                goto charge_cur_mm;
2785        /*
2786         * A racing thread's fault, or swapoff, may have already updated
2787         * the pte, and even removed page from swap cache: in those cases
2788         * do_swap_page()'s pte_same() test will fail; but there's also a
2789         * KSM case which does need to charge the page.
2790         */
2791        if (!PageSwapCache(page))
2792                goto charge_cur_mm;
2793        memcg = try_get_mem_cgroup_from_page(page);
2794        if (!memcg)
2795                goto charge_cur_mm;
2796        *memcgp = memcg;
2797        ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true);
2798        css_put(&memcg->css);
2799        if (ret == -EINTR)
2800                ret = 0;
2801        return ret;
2802charge_cur_mm:
2803        if (unlikely(!mm))
2804                mm = &init_mm;
2805        ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
2806        if (ret == -EINTR)
2807                ret = 0;
2808        return ret;
2809}
2810
2811static void
2812__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
2813                                        enum charge_type ctype)
2814{
2815        if (mem_cgroup_disabled())
2816                return;
2817        if (!memcg)
2818                return;
2819        cgroup_exclude_rmdir(&memcg->css);
2820
2821        __mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
2822        /*
2823         * Now swap is on-memory. This means this page may be
2824         * counted both as mem and swap....double count.
2825         * Fix it by uncharging from memsw. Basically, this SwapCache is stable
2826         * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
2827         * may call delete_from_swap_cache() before reach here.
2828         */
2829        if (do_swap_account && PageSwapCache(page)) {
2830                swp_entry_t ent = {.val = page_private(page)};
2831                mem_cgroup_uncharge_swap(ent);
2832        }
2833        /*
2834         * At swapin, we may charge account against cgroup which has no tasks.
2835         * So, rmdir()->pre_destroy() can be called while we do this charge.
2836         * In that case, we need to call pre_destroy() again. check it here.
2837         */
2838        cgroup_release_and_wakeup_rmdir(&memcg->css);
2839}
2840
2841void mem_cgroup_commit_charge_swapin(struct page *page,
2842                                     struct mem_cgroup *memcg)
2843{
2844        __mem_cgroup_commit_charge_swapin(page, memcg,
2845                                          MEM_CGROUP_CHARGE_TYPE_MAPPED);
2846}
2847
2848void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
2849{
2850        if (mem_cgroup_disabled())
2851                return;
2852        if (!memcg)
2853                return;
2854        __mem_cgroup_cancel_charge(memcg, 1);
2855}
2856
2857static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
2858                                   unsigned int nr_pages,
2859                                   const enum charge_type ctype)
2860{
2861        struct memcg_batch_info *batch = NULL;
2862        bool uncharge_memsw = true;
2863
2864        /* If swapout, usage of swap doesn't decrease */
2865        if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2866                uncharge_memsw = false;
2867
2868        batch = &current->memcg_batch;
2869        /*
2870         * In usual, we do css_get() when we remember memcg pointer.
2871         * But in this case, we keep res->usage until end of a series of
2872         * uncharges. Then, it's ok to ignore memcg's refcnt.
2873         */
2874        if (!batch->memcg)
2875                batch->memcg = memcg;
2876        /*
2877         * do_batch > 0 when unmapping pages or inode invalidate/truncate.
2878         * In those cases, all pages freed continuously can be expected to be in
2879         * the same cgroup and we have chance to coalesce uncharges.
2880         * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
2881         * because we want to do uncharge as soon as possible.
2882         */
2883
2884        if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
2885                goto direct_uncharge;
2886
2887        if (nr_pages > 1)
2888                goto direct_uncharge;
2889
2890        /*
2891         * In typical case, batch->memcg == mem. This means we can
2892         * merge a series of uncharges to an uncharge of res_counter.
2893         * If not, we uncharge res_counter ony by one.
2894         */
2895        if (batch->memcg != memcg)
2896                goto direct_uncharge;
2897        /* remember freed charge and uncharge it later */
2898        batch->nr_pages++;
2899        if (uncharge_memsw)
2900                batch->memsw_nr_pages++;
2901        return;
2902direct_uncharge:
2903        res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
2904        if (uncharge_memsw)
2905                res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
2906        if (unlikely(batch->memcg != memcg))
2907                memcg_oom_recover(memcg);
2908}
2909
2910/*
2911 * uncharge if !page_mapped(page)
2912 */
2913static struct mem_cgroup *
2914__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
2915{
2916        struct mem_cgroup *memcg = NULL;
2917        unsigned int nr_pages = 1;
2918        struct page_cgroup *pc;
2919        bool anon;
2920
2921        if (mem_cgroup_disabled())
2922                return NULL;
2923
2924        if (PageSwapCache(page))
2925                return NULL;
2926
2927        if (PageTransHuge(page)) {
2928                nr_pages <<= compound_order(page);
2929                VM_BUG_ON(!PageTransHuge(page));
2930        }
2931        /*
2932         * Check if our page_cgroup is valid
2933         */
2934        pc = lookup_page_cgroup(page);
2935        if (unlikely(!PageCgroupUsed(pc)))
2936                return NULL;
2937
2938        lock_page_cgroup(pc);
2939
2940        memcg = pc->mem_cgroup;
2941
2942        if (!PageCgroupUsed(pc))
2943                goto unlock_out;
2944
2945        anon = PageAnon(page);
2946
2947        switch (ctype) {
2948        case MEM_CGROUP_CHARGE_TYPE_MAPPED:
2949                /*
2950                 * Generally PageAnon tells if it's the anon statistics to be
2951                 * updated; but sometimes e.g. mem_cgroup_uncharge_page() is
2952                 * used before page reached the stage of being marked PageAnon.
2953                 */
2954                anon = true;
2955                /* fallthrough */
2956        case MEM_CGROUP_CHARGE_TYPE_DROP:
2957                /* See mem_cgroup_prepare_migration() */
2958                if (page_mapped(page) || PageCgroupMigration(pc))
2959                        goto unlock_out;
2960                break;
2961        case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
2962                if (!PageAnon(page)) {  /* Shared memory */
2963                        if (page->mapping && !page_is_file_cache(page))
2964                                goto unlock_out;
2965                } else if (page_mapped(page)) /* Anon */
2966                                goto unlock_out;
2967                break;
2968        default:
2969                break;
2970        }
2971
2972        mem_cgroup_charge_statistics(memcg, anon, -nr_pages);
2973
2974        ClearPageCgroupUsed(pc);
2975        /*
2976         * pc->mem_cgroup is not cleared here. It will be accessed when it's
2977         * freed from LRU. This is safe because uncharged page is expected not
2978         * to be reused (freed soon). Exception is SwapCache, it's handled by
2979         * special functions.
2980         */
2981
2982        unlock_page_cgroup(pc);
2983        /*
2984         * even after unlock, we have memcg->res.usage here and this memcg
2985         * will never be freed.
2986         */
2987        memcg_check_events(memcg, page);
2988        if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
2989                mem_cgroup_swap_statistics(memcg, true);
2990                mem_cgroup_get(memcg);
2991        }
2992        if (!mem_cgroup_is_root(memcg))
2993                mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
2994
2995        return memcg;
2996
2997unlock_out:
2998        unlock_page_cgroup(pc);
2999        return NULL;
3000}
3001
3002void mem_cgroup_uncharge_page(struct page *page)
3003{
3004        /* early check. */
3005        if (page_mapped(page))
3006                return;
3007        VM_BUG_ON(page->mapping && !PageAnon(page));
3008        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
3009}
3010
3011void mem_cgroup_uncharge_cache_page(struct page *page)
3012{
3013        VM_BUG_ON(page_mapped(page));
3014        VM_BUG_ON(page->mapping);
3015        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
3016}
3017
3018/*
3019 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
3020 * In that cases, pages are freed continuously and we can expect pages
3021 * are in the same memcg. All these calls itself limits the number of
3022 * pages freed at once, then uncharge_start/end() is called properly.
3023 * This may be called prural(2) times in a context,
3024 */
3025
3026void mem_cgroup_uncharge_start(void)
3027{
3028        current->memcg_batch.do_batch++;
3029        /* We can do nest. */
3030        if (current->memcg_batch.do_batch == 1) {
3031                current->memcg_batch.memcg = NULL;
3032                current->memcg_batch.nr_pages = 0;
3033                current->memcg_batch.memsw_nr_pages = 0;
3034        }
3035}
3036
3037void mem_cgroup_uncharge_end(void)
3038{
3039        struct memcg_batch_info *batch = &current->memcg_batch;
3040
3041        if (!batch->do_batch)
3042                return;
3043
3044        batch->do_batch--;
3045        if (batch->do_batch) /* If stacked, do nothing. */
3046                return;
3047
3048        if (!batch->memcg)
3049                return;
3050        /*
3051         * This "batch->memcg" is valid without any css_get/put etc...
3052         * bacause we hide charges behind us.
3053         */
3054        if (batch->nr_pages)
3055                res_counter_uncharge(&batch->memcg->res,
3056                                     batch->nr_pages * PAGE_SIZE);
3057        if (batch->memsw_nr_pages)
3058                res_counter_uncharge(&batch->memcg->memsw,
3059                                     batch->memsw_nr_pages * PAGE_SIZE);
3060        memcg_oom_recover(batch->memcg);
3061        /* forget this pointer (for sanity check) */
3062        batch->memcg = NULL;
3063}
3064
3065#ifdef CONFIG_SWAP
3066/*
3067 * called after __delete_from_swap_cache() and drop "page" account.
3068 * memcg information is recorded to swap_cgroup of "ent"
3069 */
3070void
3071mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
3072{
3073        struct mem_cgroup *memcg;
3074        int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
3075
3076        if (!swapout) /* this was a swap cache but the swap is unused ! */
3077                ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
3078
3079        memcg = __mem_cgroup_uncharge_common(page, ctype);
3080
3081        /*
3082         * record memcg information,  if swapout && memcg != NULL,
3083         * mem_cgroup_get() was called in uncharge().
3084         */
3085        if (do_swap_account && swapout && memcg)
3086                swap_cgroup_record(ent, css_id(&memcg->css));
3087}
3088#endif
3089
3090#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
3091/*
3092 * called from swap_entry_free(). remove record in swap_cgroup and
3093 * uncharge "memsw" account.
3094 */
3095void mem_cgroup_uncharge_swap(swp_entry_t ent)
3096{
3097        struct mem_cgroup *memcg;
3098        unsigned short id;
3099
3100        if (!do_swap_account)
3101                return;
3102
3103        id = swap_cgroup_record(ent, 0);
3104        rcu_read_lock();
3105        memcg = mem_cgroup_lookup(id);
3106        if (memcg) {
3107                /*
3108                 * We uncharge this because swap is freed.
3109                 * This memcg can be obsolete one. We avoid calling css_tryget
3110                 */
3111                if (!mem_cgroup_is_root(memcg))
3112                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
3113                mem_cgroup_swap_statistics(memcg, false);
3114                mem_cgroup_put(memcg);
3115        }
3116        rcu_read_unlock();
3117}
3118
3119/**
3120 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
3121 * @entry: swap entry to be moved
3122 * @from:  mem_cgroup which the entry is moved from
3123 * @to:  mem_cgroup which the entry is moved to
3124 *
3125 * It succeeds only when the swap_cgroup's record for this entry is the same
3126 * as the mem_cgroup's id of @from.
3127 *
3128 * Returns 0 on success, -EINVAL on failure.
3129 *
3130 * The caller must have charged to @to, IOW, called res_counter_charge() about
3131 * both res and memsw, and called css_get().
3132 */
3133static int mem_cgroup_move_swap_account(swp_entry_t entry,
3134                                struct mem_cgroup *from, struct mem_cgroup *to)
3135{
3136        unsigned short old_id, new_id;
3137
3138        old_id = css_id(&from->css);
3139        new_id = css_id(&to->css);
3140
3141        if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
3142                mem_cgroup_swap_statistics(from, false);
3143                mem_cgroup_swap_statistics(to, true);
3144                /*
3145                 * This function is only called from task migration context now.
3146                 * It postpones res_counter and refcount handling till the end
3147                 * of task migration(mem_cgroup_clear_mc()) for performance
3148                 * improvement. But we cannot postpone mem_cgroup_get(to)
3149                 * because if the process that has been moved to @to does
3150                 * swap-in, the refcount of @to might be decreased to 0.
3151                 */
3152                mem_cgroup_get(to);
3153                return 0;
3154        }
3155        return -EINVAL;
3156}
3157#else
3158static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
3159                                struct mem_cgroup *from, struct mem_cgroup *to)
3160{
3161        return -EINVAL;
3162}
3163#endif
3164
3165/*
3166 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
3167 * page belongs to.
3168 */
3169int mem_cgroup_prepare_migration(struct page *page,
3170        struct page *newpage, struct mem_cgroup **memcgp, gfp_t gfp_mask)
3171{
3172        struct mem_cgroup *memcg = NULL;
3173        struct page_cgroup *pc;
3174        enum charge_type ctype;
3175        int ret = 0;
3176
3177        *memcgp = NULL;
3178
3179        VM_BUG_ON(PageTransHuge(page));
3180        if (mem_cgroup_disabled())
3181                return 0;
3182
3183        pc = lookup_page_cgroup(page);
3184        lock_page_cgroup(pc);
3185        if (PageCgroupUsed(pc)) {
3186                memcg = pc->mem_cgroup;
3187                css_get(&memcg->css);
3188                /*
3189                 * At migrating an anonymous page, its mapcount goes down
3190                 * to 0 and uncharge() will be called. But, even if it's fully
3191                 * unmapped, migration may fail and this page has to be
3192                 * charged again. We set MIGRATION flag here and delay uncharge
3193                 * until end_migration() is called
3194                 *
3195                 * Corner Case Thinking
3196                 * A)
3197                 * When the old page was mapped as Anon and it's unmap-and-freed
3198                 * while migration was ongoing.
3199                 * If unmap finds the old page, uncharge() of it will be delayed
3200                 * until end_migration(). If unmap finds a new page, it's
3201                 * uncharged when it make mapcount to be 1->0. If unmap code
3202                 * finds swap_migration_entry, the new page will not be mapped
3203                 * and end_migration() will find it(mapcount==0).
3204                 *
3205                 * B)
3206                 * When the old page was mapped but migraion fails, the kernel
3207                 * remaps it. A charge for it is kept by MIGRATION flag even
3208                 * if mapcount goes down to 0. We can do remap successfully
3209                 * without charging it again.
3210                 *
3211                 * C)
3212                 * The "old" page is under lock_page() until the end of
3213                 * migration, so, the old page itself will not be swapped-out.
3214                 * If the new page is swapped out before end_migraton, our
3215                 * hook to usual swap-out path will catch the event.
3216                 */
3217                if (PageAnon(page))
3218                        SetPageCgroupMigration(pc);
3219        }
3220        unlock_page_cgroup(pc);
3221        /*
3222         * If the page is not charged at this point,
3223         * we return here.
3224         */
3225        if (!memcg)
3226                return 0;
3227
3228        *memcgp = memcg;
3229        ret = __mem_cgroup_try_charge(NULL, gfp_mask, 1, memcgp, false);
3230        css_put(&memcg->css);/* drop extra refcnt */
3231        if (ret) {
3232                if (PageAnon(page)) {
3233                        lock_page_cgroup(pc);
3234                        ClearPageCgroupMigration(pc);
3235                        unlock_page_cgroup(pc);
3236                        /*
3237                         * The old page may be fully unmapped while we kept it.
3238                         */
3239                        mem_cgroup_uncharge_page(page);
3240                }
3241                /* we'll need to revisit this error code (we have -EINTR) */
3242                return -ENOMEM;
3243        }
3244        /*
3245         * We charge new page before it's used/mapped. So, even if unlock_page()
3246         * is called before end_migration, we can catch all events on this new
3247         * page. In the case new page is migrated but not remapped, new page's
3248         * mapcount will be finally 0 and we call uncharge in end_migration().
3249         */
3250        if (PageAnon(page))
3251                ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
3252        else if (page_is_file_cache(page))
3253                ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
3254        else
3255                ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
3256        __mem_cgroup_commit_charge(memcg, newpage, 1, ctype, false);
3257        return ret;
3258}
3259
3260/* remove redundant charge if migration failed*/
3261void mem_cgroup_end_migration(struct mem_cgroup *memcg,
3262        struct page *oldpage, struct page *newpage, bool migration_ok)
3263{
3264        struct page *used, *unused;
3265        struct page_cgroup *pc;
3266        bool anon;
3267
3268        if (!memcg)
3269                return;
3270        /* blocks rmdir() */
3271        cgroup_exclude_rmdir(&memcg->css);
3272        if (!migration_ok) {
3273                used = oldpage;
3274                unused = newpage;
3275        } else {
3276                used = newpage;
3277                unused = oldpage;
3278        }
3279        /*
3280         * We disallowed uncharge of pages under migration because mapcount
3281         * of the page goes down to zero, temporarly.
3282         * Clear the flag and check the page should be charged.
3283         */
3284        pc = lookup_page_cgroup(oldpage);
3285        lock_page_cgroup(pc);
3286        ClearPageCgroupMigration(pc);
3287        unlock_page_cgroup(pc);
3288        anon = PageAnon(used);
3289        __mem_cgroup_uncharge_common(unused,
3290                anon ? MEM_CGROUP_CHARGE_TYPE_MAPPED
3291                     : MEM_CGROUP_CHARGE_TYPE_CACHE);
3292
3293        /*
3294         * If a page is a file cache, radix-tree replacement is very atomic
3295         * and we can skip this check. When it was an Anon page, its mapcount
3296         * goes down to 0. But because we added MIGRATION flage, it's not
3297         * uncharged yet. There are several case but page->mapcount check
3298         * and USED bit check in mem_cgroup_uncharge_page() will do enough
3299         * check. (see prepare_charge() also)
3300         */
3301        if (anon)
3302                mem_cgroup_uncharge_page(used);
3303        /*
3304         * At migration, we may charge account against cgroup which has no
3305         * tasks.
3306         * So, rmdir()->pre_destroy() can be called while we do this charge.
3307         * In that case, we need to call pre_destroy() again. check it here.
3308         */
3309        cgroup_release_and_wakeup_rmdir(&memcg->css);
3310}
3311
3312/*
3313 * At replace page cache, newpage is not under any memcg but it's on
3314 * LRU. So, this function doesn't touch res_counter but handles LRU
3315 * in correct way. Both pages are locked so we cannot race with uncharge.
3316 */
3317void mem_cgroup_replace_page_cache(struct page *oldpage,
3318                                  struct page *newpage)
3319{
3320        struct mem_cgroup *memcg = NULL;
3321        struct page_cgroup *pc;
3322        enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
3323
3324        if (mem_cgroup_disabled())
3325                return;
3326
3327        pc = lookup_page_cgroup(oldpage);
3328        /* fix accounting on old pages */
3329        lock_page_cgroup(pc);
3330        if (PageCgroupUsed(pc)) {
3331                memcg = pc->mem_cgroup;
3332                mem_cgroup_charge_statistics(memcg, false, -1);
3333                ClearPageCgroupUsed(pc);
3334        }
3335        unlock_page_cgroup(pc);
3336
3337        /*
3338         * When called from shmem_replace_page(), in some cases the
3339         * oldpage has already been charged, and in some cases not.
3340         */
3341        if (!memcg)
3342                return;
3343
3344        if (PageSwapBacked(oldpage))
3345                type = MEM_CGROUP_CHARGE_TYPE_SHMEM;
3346
3347        /*
3348         * Even if newpage->mapping was NULL before starting replacement,
3349         * the newpage may be on LRU(or pagevec for LRU) already. We lock
3350         * LRU while we overwrite pc->mem_cgroup.
3351         */
3352        __mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
3353}
3354
3355#ifdef CONFIG_DEBUG_VM
3356static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
3357{
3358        struct page_cgroup *pc;
3359
3360        pc = lookup_page_cgroup(page);
3361        /*
3362         * Can be NULL while feeding pages into the page allocator for
3363         * the first time, i.e. during boot or memory hotplug;
3364         * or when mem_cgroup_disabled().
3365         */
3366        if (likely(pc) && PageCgroupUsed(pc))
3367                return pc;
3368        return NULL;
3369}
3370
3371bool mem_cgroup_bad_page_check(struct page *page)
3372{
3373        if (mem_cgroup_disabled())
3374                return false;
3375
3376        return lookup_page_cgroup_used(page) != NULL;
3377}
3378
3379void mem_cgroup_print_bad_page(struct page *page)
3380{
3381        struct page_cgroup *pc;
3382
3383        pc = lookup_page_cgroup_used(page);
3384        if (pc) {
3385                printk(KERN_ALERT "pc:%p pc->flags:%lx pc->mem_cgroup:%p\n",
3386                       pc, pc->flags, pc->mem_cgroup);
3387        }
3388}
3389#endif
3390
3391static DEFINE_MUTEX(set_limit_mutex);
3392
3393static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
3394                                unsigned long long val)
3395{
3396        int retry_count;
3397        u64 memswlimit, memlimit;
3398        int ret = 0;
3399        int children = mem_cgroup_count_children(memcg);
3400        u64 curusage, oldusage;
3401        int enlarge;
3402
3403        /*
3404         * For keeping hierarchical_reclaim simple, how long we should retry
3405         * is depends on callers. We set our retry-count to be function
3406         * of # of children which we should visit in this loop.
3407         */
3408        retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
3409
3410        oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
3411
3412        enlarge = 0;
3413        while (retry_count) {
3414                if (signal_pending(current)) {
3415                        ret = -EINTR;
3416                        break;
3417                }
3418                /*
3419                 * Rather than hide all in some function, I do this in
3420                 * open coded manner. You see what this really does.
3421                 * We have to guarantee memcg->res.limit < memcg->memsw.limit.
3422                 */
3423                mutex_lock(&set_limit_mutex);
3424                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3425                if (memswlimit < val) {
3426                        ret = -EINVAL;
3427                        mutex_unlock(&set_limit_mutex);
3428                        break;
3429                }
3430
3431                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3432                if (memlimit < val)
3433                        enlarge = 1;
3434
3435                ret = res_counter_set_limit(&memcg->res, val);
3436                if (!ret) {
3437                        if (memswlimit == val)
3438                                memcg->memsw_is_minimum = true;
3439                        else
3440                                memcg->memsw_is_minimum = false;
3441                }
3442                mutex_unlock(&set_limit_mutex);
3443
3444                if (!ret)
3445                        break;
3446
3447                mem_cgroup_reclaim(memcg, GFP_KERNEL,
3448                                   MEM_CGROUP_RECLAIM_SHRINK);
3449                curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
3450                /* Usage is reduced ? */
3451                if (curusage >= oldusage)
3452                        retry_count--;
3453                else
3454                        oldusage = curusage;
3455        }
3456        if (!ret && enlarge)
3457                memcg_oom_recover(memcg);
3458
3459        return ret;
3460}
3461
3462static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
3463                                        unsigned long long val)
3464{
3465        int retry_count;
3466        u64 memlimit, memswlimit, oldusage, curusage;
3467        int children = mem_cgroup_count_children(memcg);
3468        int ret = -EBUSY;
3469        int enlarge = 0;
3470
3471        /* see mem_cgroup_resize_res_limit */
3472        retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
3473        oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
3474        while (retry_count) {
3475                if (signal_pending(current)) {
3476                        ret = -EINTR;
3477                        break;
3478                }
3479                /*
3480                 * Rather than hide all in some function, I do this in
3481                 * open coded manner. You see what this really does.
3482                 * We have to guarantee memcg->res.limit < memcg->memsw.limit.
3483                 */
3484                mutex_lock(&set_limit_mutex);
3485                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3486                if (memlimit > val) {
3487                        ret = -EINVAL;
3488                        mutex_unlock(&set_limit_mutex);
3489                        break;
3490                }
3491                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3492                if (memswlimit < val)
3493                        enlarge = 1;
3494                ret = res_counter_set_limit(&memcg->memsw, val);
3495                if (!ret) {
3496                        if (memlimit == val)
3497                                memcg->memsw_is_minimum = true;
3498                        else
3499                                memcg->memsw_is_minimum = false;
3500                }
3501                mutex_unlock(&set_limit_mutex);
3502
3503                if (!ret)
3504                        break;
3505
3506                mem_cgroup_reclaim(memcg, GFP_KERNEL,
3507                                   MEM_CGROUP_RECLAIM_NOSWAP |
3508                                   MEM_CGROUP_RECLAIM_SHRINK);
3509                curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
3510                /* Usage is reduced ? */
3511                if (curusage >= oldusage)
3512                        retry_count--;
3513                else
3514                        oldusage = curusage;
3515        }
3516        if (!ret && enlarge)
3517                memcg_oom_recover(memcg);
3518        return ret;
3519}
3520
3521unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
3522                                            gfp_t gfp_mask,
3523                                            unsigned long *total_scanned)
3524{
3525        unsigned long nr_reclaimed = 0;
3526        struct mem_cgroup_per_zone *mz, *next_mz = NULL;
3527        unsigned long reclaimed;
3528        int loop = 0;
3529        struct mem_cgroup_tree_per_zone *mctz;
3530        unsigned long long excess;
3531        unsigned long nr_scanned;
3532
3533        if (order > 0)
3534                return 0;
3535
3536        mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
3537        /*
3538         * This loop can run a while, specially if mem_cgroup's continuously
3539         * keep exceeding their soft limit and putting the system under
3540         * pressure
3541         */
3542        do {
3543                if (next_mz)
3544                        mz = next_mz;
3545                else
3546                        mz = mem_cgroup_largest_soft_limit_node(mctz);
3547                if (!mz)
3548                        break;
3549
3550                nr_scanned = 0;
3551                reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone,
3552                                                    gfp_mask, &nr_scanned);
3553                nr_reclaimed += reclaimed;
3554                *total_scanned += nr_scanned;
3555                spin_lock(&mctz->lock);
3556
3557                /*
3558                 * If we failed to reclaim anything from this memory cgroup
3559                 * it is time to move on to the next cgroup
3560                 */
3561                next_mz = NULL;
3562                if (!reclaimed) {
3563                        do {
3564                                /*
3565                                 * Loop until we find yet another one.
3566                                 *
3567                                 * By the time we get the soft_limit lock
3568                                 * again, someone might have aded the
3569                                 * group back on the RB tree. Iterate to
3570                                 * make sure we get a different mem.
3571                                 * mem_cgroup_largest_soft_limit_node returns
3572                                 * NULL if no other cgroup is present on
3573                                 * the tree
3574                                 */
3575                                next_mz =
3576                                __mem_cgroup_largest_soft_limit_node(mctz);
3577                                if (next_mz == mz)
3578                                        css_put(&next_mz->memcg->css);
3579                                else /* next_mz == NULL or other memcg */
3580                                        break;
3581                        } while (1);
3582                }
3583                __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
3584                excess = res_counter_soft_limit_excess(&mz->memcg->res);
3585                /*
3586                 * One school of thought says that we should not add
3587                 * back the node to the tree if reclaim returns 0.
3588                 * But our reclaim could return 0, simply because due
3589                 * to priority we are exposing a smaller subset of
3590                 * memory to reclaim from. Consider this as a longer
3591                 * term TODO.
3592                 */
3593                /* If excess == 0, no tree ops */
3594                __mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess);
3595                spin_unlock(&mctz->lock);
3596                css_put(&mz->memcg->css);
3597                loop++;
3598                /*
3599                 * Could not reclaim anything and there are no more
3600                 * mem cgroups to try or we seem to be looping without
3601                 * reclaiming anything.
3602                 */
3603                if (!nr_reclaimed &&
3604                        (next_mz == NULL ||
3605                        loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
3606                        break;
3607        } while (!nr_reclaimed);
3608        if (next_mz)
3609                css_put(&next_mz->memcg->css);
3610        return nr_reclaimed;
3611}
3612
3613/*
3614 * This routine traverse page_cgroup in given list and drop them all.
3615 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
3616 */
3617static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
3618                                int node, int zid, enum lru_list lru)
3619{
3620        struct mem_cgroup_per_zone *mz;
3621        unsigned long flags, loop;
3622        struct list_head *list;
3623        struct page *busy;
3624        struct zone *zone;
3625        int ret = 0;
3626
3627        zone = &NODE_DATA(node)->node_zones[zid];
3628        mz = mem_cgroup_zoneinfo(memcg, node, zid);
3629        list = &mz->lruvec.lists[lru];
3630
3631        loop = mz->lru_size[lru];
3632        /* give some margin against EBUSY etc...*/
3633        loop += 256;
3634        busy = NULL;
3635        while (loop--) {
3636                struct page_cgroup *pc;
3637                struct page *page;
3638
3639                ret = 0;
3640                spin_lock_irqsave(&zone->lru_lock, flags);
3641                if (list_empty(list)) {
3642                        spin_unlock_irqrestore(&zone->lru_lock, flags);
3643                        break;
3644                }
3645                page = list_entry(list->prev, struct page, lru);
3646                if (busy == page) {
3647                        list_move(&page->lru, list);
3648                        busy = NULL;
3649                        spin_unlock_irqrestore(&zone->lru_lock, flags);
3650                        continue;
3651                }
3652                spin_unlock_irqrestore(&zone->lru_lock, flags);
3653
3654                pc = lookup_page_cgroup(page);
3655
3656                ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL);
3657                if (ret == -ENOMEM || ret == -EINTR)
3658                        break;
3659
3660                if (ret == -EBUSY || ret == -EINVAL) {
3661                        /* found lock contention or "pc" is obsolete. */
3662                        busy = page;
3663                        cond_resched();
3664                } else
3665                        busy = NULL;
3666        }
3667
3668        if (!ret && !list_empty(list))
3669                return -EBUSY;
3670        return ret;
3671}
3672
3673/*
3674 * make mem_cgroup's charge to be 0 if there is no task.
3675 * This enables deleting this mem_cgroup.
3676 */
3677static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)
3678{
3679        int ret;
3680        int node, zid, shrink;
3681        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
3682        struct cgroup *cgrp = memcg->css.cgroup;
3683
3684        css_get(&memcg->css);
3685
3686        shrink = 0;
3687        /* should free all ? */
3688        if (free_all)
3689                goto try_to_free;
3690move_account:
3691        do {
3692                ret = -EBUSY;
3693                if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
3694                        goto out;
3695                ret = -EINTR;
3696                if (signal_pending(current))
3697                        goto out;
3698                /* This is for making all *used* pages to be on LRU. */
3699                lru_add_drain_all();
3700                drain_all_stock_sync(memcg);
3701                ret = 0;
3702                mem_cgroup_start_move(memcg);
3703                for_each_node_state(node, N_HIGH_MEMORY) {
3704                        for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
3705                                enum lru_list lru;
3706                                for_each_lru(lru) {
3707                                        ret = mem_cgroup_force_empty_list(memcg,
3708                                                        node, zid, lru);
3709                                        if (ret)
3710                                                break;
3711                                }
3712                        }
3713                        if (ret)
3714                                break;
3715                }
3716                mem_cgroup_end_move(memcg);
3717                memcg_oom_recover(memcg);
3718                /* it seems parent cgroup doesn't have enough mem */
3719                if (ret == -ENOMEM)
3720                        goto try_to_free;
3721                cond_resched();
3722        /* "ret" should also be checked to ensure all lists are empty. */
3723        } while (res_counter_read_u64(&memcg->res, RES_USAGE) > 0 || ret);
3724out:
3725        css_put(&memcg->css);
3726        return ret;
3727
3728try_to_free:
3729        /* returns EBUSY if there is a task or if we come here twice. */
3730        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
3731                ret = -EBUSY;
3732                goto out;
3733        }
3734        /* we call try-to-free pages for make this cgroup empty */
3735        lru_add_drain_all();
3736        /* try to free all pages in this cgroup */
3737        shrink = 1;
3738        while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
3739                int progress;
3740
3741                if (signal_pending(current)) {
3742                        ret = -EINTR;
3743                        goto out;
3744                }
3745                progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
3746                                                false);
3747                if (!progress) {
3748                        nr_retries--;
3749                        /* maybe some writeback is necessary */
3750                        congestion_wait(BLK_RW_ASYNC, HZ/10);
3751                }
3752
3753        }
3754        lru_add_drain();
3755        /* try move_account...there may be some *locked* pages. */
3756        goto move_account;
3757}
3758
3759static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
3760{
3761        return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
3762}
3763
3764
3765static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
3766{
3767        return mem_cgroup_from_cont(cont)->use_hierarchy;
3768}
3769
3770static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
3771                                        u64 val)
3772{
3773        int retval = 0;
3774        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3775        struct cgroup *parent = cont->parent;
3776        struct mem_cgroup *parent_memcg = NULL;
3777
3778        if (parent)
3779                parent_memcg = mem_cgroup_from_cont(parent);
3780
3781        cgroup_lock();
3782        /*
3783         * If parent's use_hierarchy is set, we can't make any modifications
3784         * in the child subtrees. If it is unset, then the change can
3785         * occur, provided the current cgroup has no children.
3786         *
3787         * For the root cgroup, parent_mem is NULL, we allow value to be
3788         * set if there are no children.
3789         */
3790        if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
3791                                (val == 1 || val == 0)) {
3792                if (list_empty(&cont->children))
3793                        memcg->use_hierarchy = val;
3794                else
3795                        retval = -EBUSY;
3796        } else
3797                retval = -EINVAL;
3798        cgroup_unlock();
3799
3800        return retval;
3801}
3802
3803
3804static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
3805                                               enum mem_cgroup_stat_index idx)
3806{
3807        struct mem_cgroup *iter;
3808        long val = 0;
3809
3810        /* Per-cpu values can be negative, use a signed accumulator */
3811        for_each_mem_cgroup_tree(iter, memcg)
3812                val += mem_cgroup_read_stat(iter, idx);
3813
3814        if (val < 0) /* race ? */
3815                val = 0;
3816        return val;
3817}
3818
3819static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
3820{
3821        u64 val;
3822
3823        if (!mem_cgroup_is_root(memcg)) {
3824                if (!swap)
3825                        return res_counter_read_u64(&memcg->res, RES_USAGE);
3826                else
3827                        return res_counter_read_u64(&memcg->memsw, RES_USAGE);
3828        }
3829
3830        val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
3831        val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
3832
3833        if (swap)
3834                val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAPOUT);
3835
3836        return val << PAGE_SHIFT;
3837}
3838
3839static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
3840                               struct file *file, char __user *buf,
3841                               size_t nbytes, loff_t *ppos)
3842{
3843        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3844        char str[64];
3845        u64 val;
3846        int type, name, len;
3847
3848        type = MEMFILE_TYPE(cft->private);
3849        name = MEMFILE_ATTR(cft->private);
3850
3851        if (!do_swap_account && type == _MEMSWAP)
3852                return -EOPNOTSUPP;
3853
3854        switch (type) {
3855        case _MEM:
3856                if (name == RES_USAGE)
3857                        val = mem_cgroup_usage(memcg, false);
3858                else
3859                        val = res_counter_read_u64(&memcg->res, name);
3860                break;
3861        case _MEMSWAP:
3862                if (name == RES_USAGE)
3863                        val = mem_cgroup_usage(memcg, true);
3864                else
3865                        val = res_counter_read_u64(&memcg->memsw, name);
3866                break;
3867        default:
3868                BUG();
3869        }
3870
3871        len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
3872        return simple_read_from_buffer(buf, nbytes, ppos, str, len);
3873}
3874/*
3875 * The user of this function is...
3876 * RES_LIMIT.
3877 */
3878static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
3879                            const char *buffer)
3880{
3881        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3882        int type, name;
3883        unsigned long long val;
3884        int ret;
3885
3886        type = MEMFILE_TYPE(cft->private);
3887        name = MEMFILE_ATTR(cft->private);
3888
3889        if (!do_swap_account && type == _MEMSWAP)
3890                return -EOPNOTSUPP;
3891
3892        switch (name) {
3893        case RES_LIMIT:
3894                if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3895                        ret = -EINVAL;
3896                        break;
3897                }
3898                /* This function does all necessary parse...reuse it */
3899                ret = res_counter_memparse_write_strategy(buffer, &val);
3900                if (ret)
3901                        break;
3902                if (type == _MEM)
3903                        ret = mem_cgroup_resize_limit(memcg, val);
3904                else
3905                        ret = mem_cgroup_resize_memsw_limit(memcg, val);
3906                break;
3907        case RES_SOFT_LIMIT:
3908                ret = res_counter_memparse_write_strategy(buffer, &val);
3909                if (ret)
3910                        break;
3911                /*
3912                 * For memsw, soft limits are hard to implement in terms
3913                 * of semantics, for now, we support soft limits for
3914                 * control without swap
3915                 */
3916                if (type == _MEM)
3917                        ret = res_counter_set_soft_limit(&memcg->res, val);
3918                else
3919                        ret = -EINVAL;
3920                break;
3921        default:
3922                ret = -EINVAL; /* should be BUG() ? */
3923                break;
3924        }
3925        return ret;
3926}
3927
3928static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
3929                unsigned long long *mem_limit, unsigned long long *memsw_limit)
3930{
3931        struct cgroup *cgroup;
3932        unsigned long long min_limit, min_memsw_limit, tmp;
3933
3934        min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3935        min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3936        cgroup = memcg->css.cgroup;
3937        if (!memcg->use_hierarchy)
3938                goto out;
3939
3940        while (cgroup->parent) {
3941                cgroup = cgroup->parent;
3942                memcg = mem_cgroup_from_cont(cgroup);
3943                if (!memcg->use_hierarchy)
3944                        break;
3945                tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
3946                min_limit = min(min_limit, tmp);
3947                tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3948                min_memsw_limit = min(min_memsw_limit, tmp);
3949        }
3950out:
3951        *mem_limit = min_limit;
3952        *memsw_limit = min_memsw_limit;
3953}
3954
3955static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
3956{
3957        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3958        int type, name;
3959
3960        type = MEMFILE_TYPE(event);
3961        name = MEMFILE_ATTR(event);
3962
3963        if (!do_swap_account && type == _MEMSWAP)
3964                return -EOPNOTSUPP;
3965
3966        switch (name) {
3967        case RES_MAX_USAGE:
3968                if (type == _MEM)
3969                        res_counter_reset_max(&memcg->res);
3970                else
3971                        res_counter_reset_max(&memcg->memsw);
3972                break;
3973        case RES_FAILCNT:
3974                if (type == _MEM)
3975                        res_counter_reset_failcnt(&memcg->res);
3976                else
3977                        res_counter_reset_failcnt(&memcg->memsw);
3978                break;
3979        }
3980
3981        return 0;
3982}
3983
3984static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
3985                                        struct cftype *cft)
3986{
3987        return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
3988}
3989
3990#ifdef CONFIG_MMU
3991static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
3992                                        struct cftype *cft, u64 val)
3993{
3994        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
3995
3996        if (val >= (1 << NR_MOVE_TYPE))
3997                return -EINVAL;
3998        /*
3999         * We check this value several times in both in can_attach() and
4000         * attach(), so we need cgroup lock to prevent this value from being
4001         * inconsistent.
4002         */
4003        cgroup_lock();
4004        memcg->move_charge_at_immigrate = val;
4005        cgroup_unlock();
4006
4007        return 0;
4008}
4009#else
4010static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
4011                                        struct cftype *cft, u64 val)
4012{
4013        return -ENOSYS;
4014}
4015#endif
4016
4017#ifdef CONFIG_NUMA
4018static int mem_control_numa_stat_show(struct cgroup *cont, struct cftype *cft,
4019                                      struct seq_file *m)
4020{
4021        int nid;
4022        unsigned long total_nr, file_nr, anon_nr, unevictable_nr;
4023        unsigned long node_nr;
4024        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4025
4026        total_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL);
4027        seq_printf(m, "total=%lu", total_nr);
4028        for_each_node_state(nid, N_HIGH_MEMORY) {
4029                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL);
4030                seq_printf(m, " N%d=%lu", nid, node_nr);
4031        }
4032        seq_putc(m, '\n');
4033
4034        file_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_FILE);
4035        seq_printf(m, "file=%lu", file_nr);
4036        for_each_node_state(nid, N_HIGH_MEMORY) {
4037                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
4038                                LRU_ALL_FILE);
4039                seq_printf(m, " N%d=%lu", nid, node_nr);
4040        }
4041        seq_putc(m, '\n');
4042
4043        anon_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_ANON);
4044        seq_printf(m, "anon=%lu", anon_nr);
4045        for_each_node_state(nid, N_HIGH_MEMORY) {
4046                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
4047                                LRU_ALL_ANON);
4048                seq_printf(m, " N%d=%lu", nid, node_nr);
4049        }
4050        seq_putc(m, '\n');
4051
4052        unevictable_nr = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_UNEVICTABLE));
4053        seq_printf(m, "unevictable=%lu", unevictable_nr);
4054        for_each_node_state(nid, N_HIGH_MEMORY) {
4055                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
4056                                BIT(LRU_UNEVICTABLE));
4057                seq_printf(m, " N%d=%lu", nid, node_nr);
4058        }
4059        seq_putc(m, '\n');
4060        return 0;
4061}
4062#endif /* CONFIG_NUMA */
4063
4064static const char * const mem_cgroup_lru_names[] = {
4065        "inactive_anon",
4066        "active_anon",
4067        "inactive_file",
4068        "active_file",
4069        "unevictable",
4070};
4071
4072static inline void mem_cgroup_lru_names_not_uptodate(void)
4073{
4074        BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
4075}
4076
4077static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
4078                                 struct seq_file *m)
4079{
4080        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4081        struct mem_cgroup *mi;
4082        unsigned int i;
4083
4084        for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
4085                if (i == MEM_CGROUP_STAT_SWAPOUT && !do_swap_account)
4086                        continue;
4087                seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i],
4088                           mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
4089        }
4090
4091        for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++)
4092                seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i],
4093                           mem_cgroup_read_events(memcg, i));
4094
4095        for (i = 0; i < NR_LRU_LISTS; i++)
4096                seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i],
4097                           mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);
4098
4099        /* Hierarchical information */
4100        {
4101                unsigned long long limit, memsw_limit;
4102                memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
4103                seq_printf(m, "hierarchical_memory_limit %llu\n", limit);
4104                if (do_swap_account)
4105                        seq_printf(m, "hierarchical_memsw_limit %llu\n",
4106                                   memsw_limit);
4107        }
4108
4109        for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
4110                long long val = 0;
4111
4112                if (i == MEM_CGROUP_STAT_SWAPOUT && !do_swap_account)
4113                        continue;
4114                for_each_mem_cgroup_tree(mi, memcg)
4115                        val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE;
4116                seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val);
4117        }
4118
4119        for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
4120                unsigned long long val = 0;
4121
4122                for_each_mem_cgroup_tree(mi, memcg)
4123                        val += mem_cgroup_read_events(mi, i);
4124                seq_printf(m, "total_%s %llu\n",
4125                           mem_cgroup_events_names[i], val);
4126        }
4127
4128        for (i = 0; i < NR_LRU_LISTS; i++) {
4129                unsigned long long val = 0;
4130
4131                for_each_mem_cgroup_tree(mi, memcg)
4132                        val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE;
4133                seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val);
4134        }
4135
4136#ifdef CONFIG_DEBUG_VM
4137        {
4138                int nid, zid;
4139                struct mem_cgroup_per_zone *mz;
4140                struct zone_reclaim_stat *rstat;
4141                unsigned long recent_rotated[2] = {0, 0};
4142                unsigned long recent_scanned[2] = {0, 0};
4143
4144                for_each_online_node(nid)
4145                        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
4146                                mz = mem_cgroup_zoneinfo(memcg, nid, zid);
4147                                rstat = &mz->lruvec.reclaim_stat;
4148
4149                                recent_rotated[0] += rstat->recent_rotated[0];
4150                                recent_rotated[1] += rstat->recent_rotated[1];
4151                                recent_scanned[0] += rstat->recent_scanned[0];
4152                                recent_scanned[1] += rstat->recent_scanned[1];
4153                        }
4154                seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]);
4155                seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]);
4156                seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]);
4157                seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]);
4158        }
4159#endif
4160
4161        return 0;
4162}
4163
4164static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
4165{
4166        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4167
4168        return mem_cgroup_swappiness(memcg);
4169}
4170
4171static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
4172                                       u64 val)
4173{
4174        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4175        struct mem_cgroup *parent;
4176
4177        if (val > 100)
4178                return -EINVAL;
4179
4180        if (cgrp->parent == NULL)
4181                return -EINVAL;
4182
4183        parent = mem_cgroup_from_cont(cgrp->parent);
4184
4185        cgroup_lock();
4186
4187        /* If under hierarchy, only empty-root can set this value */
4188        if ((parent->use_hierarchy) ||
4189            (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
4190                cgroup_unlock();
4191                return -EINVAL;
4192        }
4193
4194        memcg->swappiness = val;
4195
4196        cgroup_unlock();
4197
4198        return 0;
4199}
4200
4201static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
4202{
4203        struct mem_cgroup_threshold_ary *t;
4204        u64 usage;
4205        int i;
4206
4207        rcu_read_lock();
4208        if (!swap)
4209                t = rcu_dereference(memcg->thresholds.primary);
4210        else
4211                t = rcu_dereference(memcg->memsw_thresholds.primary);
4212
4213        if (!t)
4214                goto unlock;
4215
4216        usage = mem_cgroup_usage(memcg, swap);
4217
4218        /*
4219         * current_threshold points to threshold just below or equal to usage.
4220         * If it's not true, a threshold was crossed after last
4221         * call of __mem_cgroup_threshold().
4222         */
4223        i = t->current_threshold;
4224
4225        /*
4226         * Iterate backward over array of thresholds starting from
4227         * current_threshold and check if a threshold is crossed.
4228         * If none of thresholds below usage is crossed, we read
4229         * only one element of the array here.
4230         */
4231        for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
4232                eventfd_signal(t->entries[i].eventfd, 1);
4233
4234        /* i = current_threshold + 1 */
4235        i++;
4236
4237        /*
4238         * Iterate forward over array of thresholds starting from
4239         * current_threshold+1 and check if a threshold is crossed.
4240         * If none of thresholds above usage is crossed, we read
4241         * only one element of the array here.
4242         */
4243        for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
4244                eventfd_signal(t->entries[i].eventfd, 1);
4245
4246        /* Update current_threshold */
4247        t->current_threshold = i - 1;
4248unlock:
4249        rcu_read_unlock();
4250}
4251
4252static void mem_cgroup_threshold(struct mem_cgroup *memcg)
4253{
4254        while (memcg) {
4255                __mem_cgroup_threshold(memcg, false);
4256                if (do_swap_account)
4257                        __mem_cgroup_threshold(memcg, true);
4258
4259                memcg = parent_mem_cgroup(memcg);
4260        }
4261}
4262
4263static int compare_thresholds(const void *a, const void *b)
4264{
4265        const struct mem_cgroup_threshold *_a = a;
4266        const struct mem_cgroup_threshold *_b = b;
4267
4268        return _a->threshold - _b->threshold;
4269}
4270
4271static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
4272{
4273        struct mem_cgroup_eventfd_list *ev;
4274
4275        list_for_each_entry(ev, &memcg->oom_notify, list)
4276                eventfd_signal(ev->eventfd, 1);
4277        return 0;
4278}
4279
4280static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
4281{
4282        struct mem_cgroup *iter;
4283
4284        for_each_mem_cgroup_tree(iter, memcg)
4285                mem_cgroup_oom_notify_cb(iter);
4286}
4287
4288static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
4289        struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
4290{
4291        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4292        struct mem_cgroup_thresholds *thresholds;
4293        struct mem_cgroup_threshold_ary *new;
4294        int type = MEMFILE_TYPE(cft->private);
4295        u64 threshold, usage;
4296        int i, size, ret;
4297
4298        ret = res_counter_memparse_write_strategy(args, &threshold);
4299        if (ret)
4300                return ret;
4301
4302        mutex_lock(&memcg->thresholds_lock);
4303
4304        if (type == _MEM)
4305                thresholds = &memcg->thresholds;
4306        else if (type == _MEMSWAP)
4307                thresholds = &memcg->memsw_thresholds;
4308        else
4309                BUG();
4310
4311        usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
4312
4313        /* Check if a threshold crossed before adding a new one */
4314        if (thresholds->primary)
4315                __mem_cgroup_threshold(memcg, type == _MEMSWAP);
4316
4317        size = thresholds->primary ? thresholds->primary->size + 1 : 1;
4318
4319        /* Allocate memory for new array of thresholds */
4320        new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
4321                        GFP_KERNEL);
4322        if (!new) {
4323                ret = -ENOMEM;
4324                goto unlock;
4325        }
4326        new->size = size;
4327
4328        /* Copy thresholds (if any) to new array */
4329        if (thresholds->primary) {
4330                memcpy(new->entries, thresholds->primary->entries, (size - 1) *
4331                                sizeof(struct mem_cgroup_threshold));
4332        }
4333
4334        /* Add new threshold */
4335        new->entries[size - 1].eventfd = eventfd;
4336        new->entries[size - 1].threshold = threshold;
4337
4338        /* Sort thresholds. Registering of new threshold isn't time-critical */
4339        sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
4340                        compare_thresholds, NULL);
4341
4342        /* Find current threshold */
4343        new->current_threshold = -1;
4344        for (i = 0; i < size; i++) {
4345                if (new->entries[i].threshold <= usage) {
4346                        /*
4347                         * new->current_threshold will not be used until
4348                         * rcu_assign_pointer(), so it's safe to increment
4349                         * it here.
4350                         */
4351                        ++new->current_threshold;
4352                } else
4353                        break;
4354        }
4355
4356        /* Free old spare buffer and save old primary buffer as spare */
4357        kfree(thresholds->spare);
4358        thresholds->spare = thresholds->primary;
4359
4360        rcu_assign_pointer(thresholds->primary, new);
4361
4362        /* To be sure that nobody uses thresholds */
4363        synchronize_rcu();
4364
4365unlock:
4366        mutex_unlock(&memcg->thresholds_lock);
4367
4368        return ret;
4369}
4370
4371static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
4372        struct cftype *cft, struct eventfd_ctx *eventfd)
4373{
4374        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4375        struct mem_cgroup_thresholds *thresholds;
4376        struct mem_cgroup_threshold_ary *new;
4377        int type = MEMFILE_TYPE(cft->private);
4378        u64 usage;
4379        int i, j, size;
4380
4381        mutex_lock(&memcg->thresholds_lock);
4382        if (type == _MEM)
4383                thresholds = &memcg->thresholds;
4384        else if (type == _MEMSWAP)
4385                thresholds = &memcg->memsw_thresholds;
4386        else
4387                BUG();
4388
4389        if (!thresholds->primary)
4390                goto unlock;
4391
4392        usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
4393
4394        /* Check if a threshold crossed before removing */
4395        __mem_cgroup_threshold(memcg, type == _MEMSWAP);
4396
4397        /* Calculate new number of threshold */
4398        size = 0;
4399        for (i = 0; i < thresholds->primary->size; i++) {
4400                if (thresholds->primary->entries[i].eventfd != eventfd)
4401                        size++;
4402        }
4403
4404        new = thresholds->spare;
4405
4406        /* Set thresholds array to NULL if we don't have thresholds */
4407        if (!size) {
4408                kfree(new);
4409                new = NULL;
4410                goto swap_buffers;
4411        }
4412
4413        new->size = size;
4414
4415        /* Copy thresholds and find current threshold */
4416        new->current_threshold = -1;
4417        for (i = 0, j = 0; i < thresholds->primary->size; i++) {
4418                if (thresholds->primary->entries[i].eventfd == eventfd)
4419                        continue;
4420
4421                new->entries[j] = thresholds->primary->entries[i];
4422                if (new->entries[j].threshold <= usage) {
4423                        /*
4424                         * new->current_threshold will not be used
4425                         * until rcu_assign_pointer(), so it's safe to increment
4426                         * it here.
4427                         */
4428                        ++new->current_threshold;
4429                }
4430                j++;
4431        }
4432
4433swap_buffers:
4434        /* Swap primary and spare array */
4435        thresholds->spare = thresholds->primary;
4436        /* If all events are unregistered, free the spare array */
4437        if (!new) {
4438                kfree(thresholds->spare);
4439                thresholds->spare = NULL;
4440        }
4441
4442        rcu_assign_pointer(thresholds->primary, new);
4443
4444        /* To be sure that nobody uses thresholds */
4445        synchronize_rcu();
4446unlock:
4447        mutex_unlock(&memcg->thresholds_lock);
4448}
4449
4450static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
4451        struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
4452{
4453        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4454        struct mem_cgroup_eventfd_list *event;
4455        int type = MEMFILE_TYPE(cft->private);
4456
4457        BUG_ON(type != _OOM_TYPE);
4458        event = kmalloc(sizeof(*event), GFP_KERNEL);
4459        if (!event)
4460                return -ENOMEM;
4461
4462        spin_lock(&memcg_oom_lock);
4463
4464        event->eventfd = eventfd;
4465        list_add(&event->list, &memcg->oom_notify);
4466
4467        /* already in OOM ? */
4468        if (atomic_read(&memcg->under_oom))
4469                eventfd_signal(eventfd, 1);
4470        spin_unlock(&memcg_oom_lock);
4471
4472        return 0;
4473}
4474
4475static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
4476        struct cftype *cft, struct eventfd_ctx *eventfd)
4477{
4478        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4479        struct mem_cgroup_eventfd_list *ev, *tmp;
4480        int type = MEMFILE_TYPE(cft->private);
4481
4482        BUG_ON(type != _OOM_TYPE);
4483
4484        spin_lock(&memcg_oom_lock);
4485
4486        list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
4487                if (ev->eventfd == eventfd) {
4488                        list_del(&ev->list);
4489                        kfree(ev);
4490                }
4491        }
4492
4493        spin_unlock(&memcg_oom_lock);
4494}
4495
4496static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
4497        struct cftype *cft,  struct cgroup_map_cb *cb)
4498{
4499        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4500
4501        cb->fill(cb, "oom_kill_disable", memcg->oom_kill_disable);
4502
4503        if (atomic_read(&memcg->under_oom))
4504                cb->fill(cb, "under_oom", 1);
4505        else
4506                cb->fill(cb, "under_oom", 0);
4507        return 0;
4508}
4509
4510static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
4511        struct cftype *cft, u64 val)
4512{
4513        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4514        struct mem_cgroup *parent;
4515
4516        /* cannot set to root cgroup and only 0 and 1 are allowed */
4517        if (!cgrp->parent || !((val == 0) || (val == 1)))
4518                return -EINVAL;
4519
4520        parent = mem_cgroup_from_cont(cgrp->parent);
4521
4522        cgroup_lock();
4523        /* oom-kill-disable is a flag for subhierarchy. */
4524        if ((parent->use_hierarchy) ||
4525            (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
4526                cgroup_unlock();
4527                return -EINVAL;
4528        }
4529        memcg->oom_kill_disable = val;
4530        if (!val)
4531                memcg_oom_recover(memcg);
4532        cgroup_unlock();
4533        return 0;
4534}
4535
4536#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
4537static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
4538{
4539        return mem_cgroup_sockets_init(memcg, ss);
4540};
4541
4542static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
4543{
4544        mem_cgroup_sockets_destroy(memcg);
4545}
4546#else
4547static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
4548{
4549        return 0;
4550}
4551
4552static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
4553{
4554}
4555#endif
4556
4557static struct cftype mem_cgroup_files[] = {
4558        {
4559                .name = "usage_in_bytes",
4560                .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
4561                .read = mem_cgroup_read,
4562                .register_event = mem_cgroup_usage_register_event,
4563                .unregister_event = mem_cgroup_usage_unregister_event,
4564        },
4565        {
4566                .name = "max_usage_in_bytes",
4567                .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
4568                .trigger = mem_cgroup_reset,
4569                .read = mem_cgroup_read,
4570        },
4571        {
4572                .name = "limit_in_bytes",
4573                .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
4574                .write_string = mem_cgroup_write,
4575                .read = mem_cgroup_read,
4576        },
4577        {
4578                .name = "soft_limit_in_bytes",
4579                .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
4580                .write_string = mem_cgroup_write,
4581                .read = mem_cgroup_read,
4582        },
4583        {
4584                .name = "failcnt",
4585                .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
4586                .trigger = mem_cgroup_reset,
4587                .read = mem_cgroup_read,
4588        },
4589        {
4590                .name = "stat",
4591                .read_seq_string = mem_control_stat_show,
4592        },
4593        {
4594                .name = "force_empty",
4595                .trigger = mem_cgroup_force_empty_write,
4596        },
4597        {
4598                .name = "use_hierarchy",
4599                .write_u64 = mem_cgroup_hierarchy_write,
4600                .read_u64 = mem_cgroup_hierarchy_read,
4601        },
4602        {
4603                .name = "swappiness",
4604                .read_u64 = mem_cgroup_swappiness_read,
4605                .write_u64 = mem_cgroup_swappiness_write,
4606        },
4607        {
4608                .name = "move_charge_at_immigrate",
4609                .read_u64 = mem_cgroup_move_charge_read,
4610                .write_u64 = mem_cgroup_move_charge_write,
4611        },
4612        {
4613                .name = "oom_control",
4614                .read_map = mem_cgroup_oom_control_read,
4615                .write_u64 = mem_cgroup_oom_control_write,
4616                .register_event = mem_cgroup_oom_register_event,
4617                .unregister_event = mem_cgroup_oom_unregister_event,
4618                .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
4619        },
4620#ifdef CONFIG_NUMA
4621        {
4622                .name = "numa_stat",
4623                .read_seq_string = mem_control_numa_stat_show,
4624        },
4625#endif
4626#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4627        {
4628                .name = "memsw.usage_in_bytes",
4629                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
4630                .read = mem_cgroup_read,
4631                .register_event = mem_cgroup_usage_register_event,
4632                .unregister_event = mem_cgroup_usage_unregister_event,
4633        },
4634        {
4635                .name = "memsw.max_usage_in_bytes",
4636                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
4637                .trigger = mem_cgroup_reset,
4638                .read = mem_cgroup_read,
4639        },
4640        {
4641                .name = "memsw.limit_in_bytes",
4642                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
4643                .write_string = mem_cgroup_write,
4644                .read = mem_cgroup_read,
4645        },
4646        {
4647                .name = "memsw.failcnt",
4648                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
4649                .trigger = mem_cgroup_reset,
4650                .read = mem_cgroup_read,
4651        },
4652#endif
4653        { },    /* terminate */
4654};
4655
4656static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
4657{
4658        struct mem_cgroup_per_node *pn;
4659        struct mem_cgroup_per_zone *mz;
4660        int zone, tmp = node;
4661        /*
4662         * This routine is called against possible nodes.
4663         * But it's BUG to call kmalloc() against offline node.
4664         *
4665         * TODO: this routine can waste much memory for nodes which will
4666         *       never be onlined. It's better to use memory hotplug callback
4667         *       function.
4668         */
4669        if (!node_state(node, N_NORMAL_MEMORY))
4670                tmp = -1;
4671        pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
4672        if (!pn)
4673                return 1;
4674
4675        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4676                mz = &pn->zoneinfo[zone];
4677                lruvec_init(&mz->lruvec, &NODE_DATA(node)->node_zones[zone]);
4678                mz->usage_in_excess = 0;
4679                mz->on_tree = false;
4680                mz->memcg = memcg;
4681        }
4682        memcg->info.nodeinfo[node] = pn;
4683        return 0;
4684}
4685
4686static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
4687{
4688        kfree(memcg->info.nodeinfo[node]);
4689}
4690
4691static struct mem_cgroup *mem_cgroup_alloc(void)
4692{
4693        struct mem_cgroup *memcg;
4694        int size = sizeof(struct mem_cgroup);
4695
4696        /* Can be very big if MAX_NUMNODES is very big */
4697        if (size < PAGE_SIZE)
4698                memcg = kzalloc(size, GFP_KERNEL);
4699        else
4700                memcg = vzalloc(size);
4701
4702        if (!memcg)
4703                return NULL;
4704
4705        memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
4706        if (!memcg->stat)
4707                goto out_free;
4708        spin_lock_init(&memcg->pcp_counter_lock);
4709        return memcg;
4710
4711out_free:
4712        if (size < PAGE_SIZE)
4713                kfree(memcg);
4714        else
4715                vfree(memcg);
4716        return NULL;
4717}
4718
4719/*
4720 * Helpers for freeing a kmalloc()ed/vzalloc()ed mem_cgroup by RCU,
4721 * but in process context.  The work_freeing structure is overlaid
4722 * on the rcu_freeing structure, which itself is overlaid on memsw.
4723 */
4724static void free_work(struct work_struct *work)
4725{
4726        struct mem_cgroup *memcg;
4727        int size = sizeof(struct mem_cgroup);
4728
4729        memcg = container_of(work, struct mem_cgroup, work_freeing);
4730        /*
4731         * We need to make sure that (at least for now), the jump label
4732         * destruction code runs outside of the cgroup lock. This is because
4733         * get_online_cpus(), which is called from the static_branch update,
4734         * can't be called inside the cgroup_lock. cpusets are the ones
4735         * enforcing this dependency, so if they ever change, we might as well.
4736         *
4737         * schedule_work() will guarantee this happens. Be careful if you need
4738         * to move this code around, and make sure it is outside
4739         * the cgroup_lock.
4740         */
4741        disarm_sock_keys(memcg);
4742        if (size < PAGE_SIZE)
4743                kfree(memcg);
4744        else
4745                vfree(memcg);
4746}
4747
4748static void free_rcu(struct rcu_head *rcu_head)
4749{
4750        struct mem_cgroup *memcg;
4751
4752        memcg = container_of(rcu_head, struct mem_cgroup, rcu_freeing);
4753        INIT_WORK(&memcg->work_freeing, free_work);
4754        schedule_work(&memcg->work_freeing);
4755}
4756
4757/*
4758 * At destroying mem_cgroup, references from swap_cgroup can remain.
4759 * (scanning all at force_empty is too costly...)
4760 *
4761 * Instead of clearing all references at force_empty, we remember
4762 * the number of reference from swap_cgroup and free mem_cgroup when
4763 * it goes down to 0.
4764 *
4765 * Removal of cgroup itself succeeds regardless of refs from swap.
4766 */
4767
4768static void __mem_cgroup_free(struct mem_cgroup *memcg)
4769{
4770        int node;
4771
4772        mem_cgroup_remove_from_trees(memcg);
4773        free_css_id(&mem_cgroup_subsys, &memcg->css);
4774
4775        for_each_node(node)
4776                free_mem_cgroup_per_zone_info(memcg, node);
4777
4778        free_percpu(memcg->stat);
4779        call_rcu(&memcg->rcu_freeing, free_rcu);
4780}
4781
4782static void mem_cgroup_get(struct mem_cgroup *memcg)
4783{
4784        atomic_inc(&memcg->refcnt);
4785}
4786
4787static void __mem_cgroup_put(struct mem_cgroup *memcg, int count)
4788{
4789        if (atomic_sub_and_test(count, &memcg->refcnt)) {
4790                struct mem_cgroup *parent = parent_mem_cgroup(memcg);
4791                __mem_cgroup_free(memcg);
4792                if (parent)
4793                        mem_cgroup_put(parent);
4794        }
4795}
4796
4797static void mem_cgroup_put(struct mem_cgroup *memcg)
4798{
4799        __mem_cgroup_put(memcg, 1);
4800}
4801
4802/*
4803 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
4804 */
4805struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
4806{
4807        if (!memcg->res.parent)
4808                return NULL;
4809        return mem_cgroup_from_res_counter(memcg->res.parent, res);
4810}
4811EXPORT_SYMBOL(parent_mem_cgroup);
4812
4813#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
4814static void __init enable_swap_cgroup(void)
4815{
4816        if (!mem_cgroup_disabled() && really_do_swap_account)
4817                do_swap_account = 1;
4818}
4819#else
4820static void __init enable_swap_cgroup(void)
4821{
4822}
4823#endif
4824
4825static int mem_cgroup_soft_limit_tree_init(void)
4826{
4827        struct mem_cgroup_tree_per_node *rtpn;
4828        struct mem_cgroup_tree_per_zone *rtpz;
4829        int tmp, node, zone;
4830
4831        for_each_node(node) {
4832                tmp = node;
4833                if (!node_state(node, N_NORMAL_MEMORY))
4834                        tmp = -1;
4835                rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
4836                if (!rtpn)
4837                        goto err_cleanup;
4838
4839                soft_limit_tree.rb_tree_per_node[node] = rtpn;
4840
4841                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4842                        rtpz = &rtpn->rb_tree_per_zone[zone];
4843                        rtpz->rb_root = RB_ROOT;
4844                        spin_lock_init(&rtpz->lock);
4845                }
4846        }
4847        return 0;
4848
4849err_cleanup:
4850        for_each_node(node) {
4851                if (!soft_limit_tree.rb_tree_per_node[node])
4852                        break;
4853                kfree(soft_limit_tree.rb_tree_per_node[node]);
4854                soft_limit_tree.rb_tree_per_node[node] = NULL;
4855        }
4856        return 1;
4857
4858}
4859
4860static struct cgroup_subsys_state * __ref
4861mem_cgroup_create(struct cgroup *cont)
4862{
4863        struct mem_cgroup *memcg, *parent;
4864        long error = -ENOMEM;
4865        int node;
4866
4867        memcg = mem_cgroup_alloc();
4868        if (!memcg)
4869                return ERR_PTR(error);
4870
4871        for_each_node(node)
4872                if (alloc_mem_cgroup_per_zone_info(memcg, node))
4873                        goto free_out;
4874
4875        /* root ? */
4876        if (cont->parent == NULL) {
4877                int cpu;
4878                enable_swap_cgroup();
4879                parent = NULL;
4880                if (mem_cgroup_soft_limit_tree_init())
4881                        goto free_out;
4882                root_mem_cgroup = memcg;
4883                for_each_possible_cpu(cpu) {
4884                        struct memcg_stock_pcp *stock =
4885                                                &per_cpu(memcg_stock, cpu);
4886                        INIT_WORK(&stock->work, drain_local_stock);
4887                }
4888                hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
4889        } else {
4890                parent = mem_cgroup_from_cont(cont->parent);
4891                memcg->use_hierarchy = parent->use_hierarchy;
4892                memcg->oom_kill_disable = parent->oom_kill_disable;
4893        }
4894
4895        if (parent && parent->use_hierarchy) {
4896                res_counter_init(&memcg->res, &parent->res);
4897                res_counter_init(&memcg->memsw, &parent->memsw);
4898                /*
4899                 * We increment refcnt of the parent to ensure that we can
4900                 * safely access it on res_counter_charge/uncharge.
4901                 * This refcnt will be decremented when freeing this
4902                 * mem_cgroup(see mem_cgroup_put).
4903                 */
4904                mem_cgroup_get(parent);
4905        } else {
4906                res_counter_init(&memcg->res, NULL);
4907                res_counter_init(&memcg->memsw, NULL);
4908        }
4909        memcg->last_scanned_node = MAX_NUMNODES;
4910        INIT_LIST_HEAD(&memcg->oom_notify);
4911
4912        if (parent)
4913                memcg->swappiness = mem_cgroup_swappiness(parent);
4914        atomic_set(&memcg->refcnt, 1);
4915        memcg->move_charge_at_immigrate = 0;
4916        mutex_init(&memcg->thresholds_lock);
4917        spin_lock_init(&memcg->move_lock);
4918
4919        error = memcg_init_kmem(memcg, &mem_cgroup_subsys);
4920        if (error) {
4921                /*
4922                 * We call put now because our (and parent's) refcnts
4923                 * are already in place. mem_cgroup_put() will internally
4924                 * call __mem_cgroup_free, so return directly
4925                 */
4926                mem_cgroup_put(memcg);
4927                return ERR_PTR(error);
4928        }
4929        return &memcg->css;
4930free_out:
4931        __mem_cgroup_free(memcg);
4932        return ERR_PTR(error);
4933}
4934
4935static int mem_cgroup_pre_destroy(struct cgroup *cont)
4936{
4937        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4938
4939        return mem_cgroup_force_empty(memcg, false);
4940}
4941
4942static void mem_cgroup_destroy(struct cgroup *cont)
4943{
4944        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4945
4946        kmem_cgroup_destroy(memcg);
4947
4948        mem_cgroup_put(memcg);
4949}
4950
4951#ifdef CONFIG_MMU
4952/* Handlers for move charge at task migration. */
4953#define PRECHARGE_COUNT_AT_ONCE 256
4954static int mem_cgroup_do_precharge(unsigned long count)
4955{
4956        int ret = 0;
4957        int batch_count = PRECHARGE_COUNT_AT_ONCE;
4958        struct mem_cgroup *memcg = mc.to;
4959
4960        if (mem_cgroup_is_root(memcg)) {
4961                mc.precharge += count;
4962                /* we don't need css_get for root */
4963                return ret;
4964        }
4965        /* try to charge at once */
4966        if (count > 1) {
4967                struct res_counter *dummy;
4968                /*
4969                 * "memcg" cannot be under rmdir() because we've already checked
4970                 * by cgroup_lock_live_cgroup() that it is not removed and we
4971                 * are still under the same cgroup_mutex. So we can postpone
4972                 * css_get().
4973                 */
4974                if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy))
4975                        goto one_by_one;
4976                if (do_swap_account && res_counter_charge(&memcg->memsw,
4977                                                PAGE_SIZE * count, &dummy)) {
4978                        res_counter_uncharge(&memcg->res, PAGE_SIZE * count);
4979                        goto one_by_one;
4980                }
4981                mc.precharge += count;
4982                return ret;
4983        }
4984one_by_one:
4985        /* fall back to one by one charge */
4986        while (count--) {
4987                if (signal_pending(current)) {
4988                        ret = -EINTR;
4989                        break;
4990                }
4991                if (!batch_count--) {
4992                        batch_count = PRECHARGE_COUNT_AT_ONCE;
4993                        cond_resched();
4994                }
4995                ret = __mem_cgroup_try_charge(NULL,
4996                                        GFP_KERNEL, 1, &memcg, false);
4997                if (ret)
4998                        /* mem_cgroup_clear_mc() will do uncharge later */
4999                        return ret;
5000                mc.precharge++;
5001        }
5002        return ret;
5003}
5004
5005/**
5006 * get_mctgt_type - get target type of moving charge
5007 * @vma: the vma the pte to be checked belongs
5008 * @addr: the address corresponding to the pte to be checked
5009 * @ptent: the pte to be checked
5010 * @target: the pointer the target page or swap ent will be stored(can be NULL)
5011 *
5012 * Returns
5013 *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
5014 *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
5015 *     move charge. if @target is not NULL, the page is stored in target->page
5016 *     with extra refcnt got(Callers should handle it).
5017 *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
5018 *     target for charge migration. if @target is not NULL, the entry is stored
5019 *     in target->ent.
5020 *
5021 * Called with pte lock held.
5022 */
5023union mc_target {
5024        struct page     *page;
5025        swp_entry_t     ent;
5026};
5027
5028enum mc_target_type {
5029        MC_TARGET_NONE = 0,
5030        MC_TARGET_PAGE,
5031        MC_TARGET_SWAP,
5032};
5033
5034static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
5035                                                unsigned long addr, pte_t ptent)
5036{
5037        struct page *page = vm_normal_page(vma, addr, ptent);
5038
5039        if (!page || !page_mapped(page))
5040                return NULL;
5041        if (PageAnon(page)) {
5042                /* we don't move shared anon */
5043                if (!move_anon())
5044                        return NULL;
5045        } else if (!move_file())
5046                /* we ignore mapcount for file pages */
5047                return NULL;
5048        if (!get_page_unless_zero(page))
5049                return NULL;
5050
5051        return page;
5052}
5053
5054#ifdef CONFIG_SWAP
5055static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
5056                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
5057{
5058        struct page *page = NULL;
5059        swp_entry_t ent = pte_to_swp_entry(ptent);
5060
5061        if (!move_anon() || non_swap_entry(ent))
5062                return NULL;
5063        /*
5064         * Because lookup_swap_cache() updates some statistics counter,
5065         * we call find_get_page() with swapper_space directly.
5066         */
5067        page = find_get_page(&swapper_space, ent.val);
5068        if (do_swap_account)
5069                entry->val = ent.val;
5070
5071        return page;
5072}
5073#else
5074static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
5075                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
5076{
5077        return NULL;
5078}
5079#endif
5080
5081static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
5082                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
5083{
5084        struct page *page = NULL;
5085        struct address_space *mapping;
5086        pgoff_t pgoff;
5087
5088        if (!vma->vm_file) /* anonymous vma */
5089                return NULL;
5090        if (!move_file())
5091                return NULL;
5092
5093        mapping = vma->vm_file->f_mapping;
5094        if (pte_none(ptent))
5095                pgoff = linear_page_index(vma, addr);
5096        else /* pte_file(ptent) is true */
5097                pgoff = pte_to_pgoff(ptent);
5098
5099        /* page is moved even if it's not RSS of this task(page-faulted). */
5100        page = find_get_page(mapping, pgoff);
5101
5102#ifdef CONFIG_SWAP
5103        /* shmem/tmpfs may report page out on swap: account for that too. */
5104        if (radix_tree_exceptional_entry(page)) {
5105                swp_entry_t swap = radix_to_swp_entry(page);
5106                if (do_swap_account)
5107                        *entry = swap;
5108                page = find_get_page(&swapper_space, swap.val);
5109        }
5110#endif
5111        return page;
5112}
5113
5114static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
5115                unsigned long addr, pte_t ptent, union mc_target *target)
5116{
5117        struct page *page = NULL;
5118        struct page_cgroup *pc;
5119        enum mc_target_type ret = MC_TARGET_NONE;
5120        swp_entry_t ent = { .val = 0 };
5121
5122        if (pte_present(ptent))
5123                page = mc_handle_present_pte(vma, addr, ptent);
5124        else if (is_swap_pte(ptent))
5125                page = mc_handle_swap_pte(vma, addr, ptent, &ent);
5126        else if (pte_none(ptent) || pte_file(ptent))
5127                page = mc_handle_file_pte(vma, addr, ptent, &ent);
5128
5129        if (!page && !ent.val)
5130                return ret;
5131        if (page) {
5132                pc = lookup_page_cgroup(page);
5133                /*
5134                 * Do only loose check w/o page_cgroup lock.
5135                 * mem_cgroup_move_account() checks the pc is valid or not under
5136                 * the lock.
5137                 */
5138                if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
5139                        ret = MC_TARGET_PAGE;
5140                        if (target)
5141                                target->page = page;
5142                }
5143                if (!ret || !target)
5144                        put_page(page);
5145        }
5146        /* There is a swap entry and a page doesn't exist or isn't charged */
5147        if (ent.val && !ret &&
5148                        css_id(&mc.from->css) == lookup_swap_cgroup_id(ent)) {
5149                ret = MC_TARGET_SWAP;
5150                if (target)
5151                        target->ent = ent;
5152        }
5153        return ret;
5154}
5155
5156#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5157/*
5158 * We don't consider swapping or file mapped pages because THP does not
5159 * support them for now.
5160 * Caller should make sure that pmd_trans_huge(pmd) is true.
5161 */
5162static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
5163                unsigned long addr, pmd_t pmd, union mc_target *target)
5164{
5165        struct page *page = NULL;
5166        struct page_cgroup *pc;
5167        enum mc_target_type ret = MC_TARGET_NONE;
5168
5169        page = pmd_page(pmd);
5170        VM_BUG_ON(!page || !PageHead(page));
5171        if (!move_anon())
5172                return ret;
5173        pc = lookup_page_cgroup(page);
5174        if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
5175                ret = MC_TARGET_PAGE;
5176                if (target) {
5177                        get_page(page);
5178                        target->page = page;
5179                }
5180        }
5181        return ret;
5182}
5183#else
5184static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
5185                unsigned long addr, pmd_t pmd, union mc_target *target)
5186{
5187        return MC_TARGET_NONE;
5188}
5189#endif
5190
5191static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
5192                                        unsigned long addr, unsigned long end,
5193                                        struct mm_walk *walk)
5194{
5195        struct vm_area_struct *vma = walk->private;
5196        pte_t *pte;
5197        spinlock_t *ptl;
5198
5199        if (pmd_trans_huge_lock(pmd, vma) == 1) {
5200                if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
5201                        mc.precharge += HPAGE_PMD_NR;
5202                spin_unlock(&vma->vm_mm->page_table_lock);
5203                return 0;
5204        }
5205
5206        if (pmd_trans_unstable(pmd))
5207                return 0;
5208        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
5209        for (; addr != end; pte++, addr += PAGE_SIZE)
5210                if (get_mctgt_type(vma, addr, *pte, NULL))
5211                        mc.precharge++; /* increment precharge temporarily */
5212        pte_unmap_unlock(pte - 1, ptl);
5213        cond_resched();
5214
5215        return 0;
5216}
5217
5218static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
5219{
5220        unsigned long precharge;
5221        struct vm_area_struct *vma;
5222
5223        down_read(&mm->mmap_sem);
5224        for (vma = mm->mmap; vma; vma = vma->vm_next) {
5225                struct mm_walk mem_cgroup_count_precharge_walk = {
5226                        .pmd_entry = mem_cgroup_count_precharge_pte_range,
5227                        .mm = mm,
5228                        .private = vma,
5229                };
5230                if (is_vm_hugetlb_page(vma))
5231                        continue;
5232                walk_page_range(vma->vm_start, vma->vm_end,
5233                                        &mem_cgroup_count_precharge_walk);
5234        }
5235        up_read(&mm->mmap_sem);
5236
5237        precharge = mc.precharge;
5238        mc.precharge = 0;
5239
5240        return precharge;
5241}
5242
5243static int mem_cgroup_precharge_mc(struct mm_struct *mm)
5244{
5245        unsigned long precharge = mem_cgroup_count_precharge(mm);
5246
5247        VM_BUG_ON(mc.moving_task);
5248        mc.moving_task = current;
5249        return mem_cgroup_do_precharge(precharge);
5250}
5251
5252/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
5253static void __mem_cgroup_clear_mc(void)
5254{
5255        struct mem_cgroup *from = mc.from;
5256        struct mem_cgroup *to = mc.to;
5257
5258        /* we must uncharge all the leftover precharges from mc.to */
5259        if (mc.precharge) {
5260                __mem_cgroup_cancel_charge(mc.to, mc.precharge);
5261                mc.precharge = 0;
5262        }
5263        /*
5264         * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
5265         * we must uncharge here.
5266         */
5267        if (mc.moved_charge) {
5268                __mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
5269                mc.moved_charge = 0;
5270        }
5271        /* we must fixup refcnts and charges */
5272        if (mc.moved_swap) {
5273                /* uncharge swap account from the old cgroup */
5274                if (!mem_cgroup_is_root(mc.from))
5275                        res_counter_uncharge(&mc.from->memsw,
5276                                                PAGE_SIZE * mc.moved_swap);
5277                __mem_cgroup_put(mc.from, mc.moved_swap);
5278
5279                if (!mem_cgroup_is_root(mc.to)) {
5280                        /*
5281                         * we charged both to->res and to->memsw, so we should
5282                         * uncharge to->res.
5283                         */
5284                        res_counter_uncharge(&mc.to->res,
5285                                                PAGE_SIZE * mc.moved_swap);
5286                }
5287                /* we've already done mem_cgroup_get(mc.to) */
5288                mc.moved_swap = 0;
5289        }
5290        memcg_oom_recover(from);
5291        memcg_oom_recover(to);
5292        wake_up_all(&mc.waitq);
5293}
5294
5295static void mem_cgroup_clear_mc(void)
5296{
5297        struct mem_cgroup *from = mc.from;
5298
5299        /*
5300         * we must clear moving_task before waking up waiters at the end of
5301         * task migration.
5302         */
5303        mc.moving_task = NULL;
5304        __mem_cgroup_clear_mc();
5305        spin_lock(&mc.lock);
5306        mc.from = NULL;
5307        mc.to = NULL;
5308        spin_unlock(&mc.lock);
5309        mem_cgroup_end_move(from);
5310}
5311
5312static int mem_cgroup_can_attach(struct cgroup *cgroup,
5313                                 struct cgroup_taskset *tset)
5314{
5315        struct task_struct *p = cgroup_taskset_first(tset);
5316        int ret = 0;
5317        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
5318
5319        if (memcg->move_charge_at_immigrate) {
5320                struct mm_struct *mm;
5321                struct mem_cgroup *from = mem_cgroup_from_task(p);
5322
5323                VM_BUG_ON(from == memcg);
5324
5325                mm = get_task_mm(p);
5326                if (!mm)
5327                        return 0;
5328                /* We move charges only when we move a owner of the mm */
5329                if (mm->owner == p) {
5330                        VM_BUG_ON(mc.from);
5331                        VM_BUG_ON(mc.to);
5332                        VM_BUG_ON(mc.precharge);
5333                        VM_BUG_ON(mc.moved_charge);
5334                        VM_BUG_ON(mc.moved_swap);
5335                        mem_cgroup_start_move(from);
5336                        spin_lock(&mc.lock);
5337                        mc.from = from;
5338                        mc.to = memcg;
5339                        spin_unlock(&mc.lock);
5340                        /* We set mc.moving_task later */
5341
5342                        ret = mem_cgroup_precharge_mc(mm);
5343                        if (ret)
5344                                mem_cgroup_clear_mc();
5345                }
5346                mmput(mm);
5347        }
5348        return ret;
5349}
5350
5351static void mem_cgroup_cancel_attach(struct cgroup *cgroup,
5352                                     struct cgroup_taskset *tset)
5353{
5354        mem_cgroup_clear_mc();
5355}
5356
5357static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
5358                                unsigned long addr, unsigned long end,
5359                                struct mm_walk *walk)
5360{
5361        int ret = 0;
5362        struct vm_area_struct *vma = walk->private;
5363        pte_t *pte;
5364        spinlock_t *ptl;
5365        enum mc_target_type target_type;
5366        union mc_target target;
5367        struct page *page;
5368        struct page_cgroup *pc;
5369
5370        /*
5371         * We don't take compound_lock() here but no race with splitting thp
5372         * happens because:
5373         *  - if pmd_trans_huge_lock() returns 1, the relevant thp is not
5374         *    under splitting, which means there's no concurrent thp split,
5375         *  - if another thread runs into split_huge_page() just after we
5376         *    entered this if-block, the thread must wait for page table lock
5377         *    to be unlocked in __split_huge_page_splitting(), where the main
5378         *    part of thp split is not executed yet.
5379         */
5380        if (pmd_trans_huge_lock(pmd, vma) == 1) {
5381                if (mc.precharge < HPAGE_PMD_NR) {
5382                        spin_unlock(&vma->vm_mm->page_table_lock);
5383                        return 0;
5384                }
5385                target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
5386                if (target_type == MC_TARGET_PAGE) {
5387                        page = target.page;
5388                        if (!isolate_lru_page(page)) {
5389                                pc = lookup_page_cgroup(page);
5390                                if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
5391                                                        pc, mc.from, mc.to)) {
5392                                        mc.precharge -= HPAGE_PMD_NR;
5393                                        mc.moved_charge += HPAGE_PMD_NR;
5394                                }
5395                                putback_lru_page(page);
5396                        }
5397                        put_page(page);
5398                }
5399                spin_unlock(&vma->vm_mm->page_table_lock);
5400                return 0;
5401        }
5402
5403        if (pmd_trans_unstable(pmd))
5404                return 0;
5405retry:
5406        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
5407        for (; addr != end; addr += PAGE_SIZE) {
5408                pte_t ptent = *(pte++);
5409                swp_entry_t ent;
5410
5411                if (!mc.precharge)
5412                        break;
5413
5414                switch (get_mctgt_type(vma, addr, ptent, &target)) {
5415                case MC_TARGET_PAGE:
5416                        page = target.page;
5417                        if (isolate_lru_page(page))
5418                                goto put;
5419                        pc = lookup_page_cgroup(page);
5420                        if (!mem_cgroup_move_account(page, 1, pc,
5421                                                     mc.from, mc.to)) {
5422                                mc.precharge--;
5423                                /* we uncharge from mc.from later. */
5424                                mc.moved_charge++;
5425                        }
5426                        putback_lru_page(page);
5427put:                    /* get_mctgt_type() gets the page */
5428                        put_page(page);
5429                        break;
5430                case MC_TARGET_SWAP:
5431                        ent = target.ent;
5432                        if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
5433                                mc.precharge--;
5434                                /* we fixup refcnts and charges later. */
5435                                mc.moved_swap++;
5436                        }
5437                        break;
5438                default:
5439                        break;
5440                }
5441        }
5442        pte_unmap_unlock(pte - 1, ptl);
5443        cond_resched();
5444
5445        if (addr != end) {
5446                /*
5447                 * We have consumed all precharges we got in can_attach().
5448                 * We try charge one by one, but don't do any additional
5449                 * charges to mc.to if we have failed in charge once in attach()
5450                 * phase.
5451                 */
5452                ret = mem_cgroup_do_precharge(1);
5453                if (!ret)
5454                        goto retry;
5455        }
5456
5457        return ret;
5458}
5459
5460static void mem_cgroup_move_charge(struct mm_struct *mm)
5461{
5462        struct vm_area_struct *vma;
5463
5464        lru_add_drain_all();
5465retry:
5466        if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
5467                /*
5468                 * Someone who are holding the mmap_sem might be waiting in
5469                 * waitq. So we cancel all extra charges, wake up all waiters,
5470                 * and retry. Because we cancel precharges, we might not be able
5471                 * to move enough charges, but moving charge is a best-effort
5472                 * feature anyway, so it wouldn't be a big problem.
5473                 */
5474                __mem_cgroup_clear_mc();
5475                cond_resched();
5476                goto retry;
5477        }
5478        for (vma = mm->mmap; vma; vma = vma->vm_next) {
5479                int ret;
5480                struct mm_walk mem_cgroup_move_charge_walk = {
5481                        .pmd_entry = mem_cgroup_move_charge_pte_range,
5482                        .mm = mm,
5483                        .private = vma,
5484                };
5485                if (is_vm_hugetlb_page(vma))
5486                        continue;
5487                ret = walk_page_range(vma->vm_start, vma->vm_end,
5488                                                &mem_cgroup_move_charge_walk);
5489                if (ret)
5490                        /*
5491                         * means we have consumed all precharges and failed in
5492                         * doing additional charge. Just abandon here.
5493                         */
5494                        break;
5495        }
5496        up_read(&mm->mmap_sem);
5497}
5498
5499static void mem_cgroup_move_task(struct cgroup *cont,
5500                                 struct cgroup_taskset *tset)
5501{
5502        struct task_struct *p = cgroup_taskset_first(tset);
5503        struct mm_struct *mm = get_task_mm(p);
5504
5505        if (mm) {
5506                if (mc.to)
5507                        mem_cgroup_move_charge(mm);
5508                mmput(mm);
5509        }
5510        if (mc.to)
5511                mem_cgroup_clear_mc();
5512}
5513#else   /* !CONFIG_MMU */
5514static int mem_cgroup_can_attach(struct cgroup *cgroup,
5515                                 struct cgroup_taskset *tset)
5516{
5517        return 0;
5518}
5519static void mem_cgroup_cancel_attach(struct cgroup *cgroup,
5520                                     struct cgroup_taskset *tset)
5521{
5522}
5523static void mem_cgroup_move_task(struct cgroup *cont,
5524                                 struct cgroup_taskset *tset)
5525{
5526}
5527#endif
5528
5529struct cgroup_subsys mem_cgroup_subsys = {
5530        .name = "memory",
5531        .subsys_id = mem_cgroup_subsys_id,
5532        .create = mem_cgroup_create,
5533        .pre_destroy = mem_cgroup_pre_destroy,
5534        .destroy = mem_cgroup_destroy,
5535        .can_attach = mem_cgroup_can_attach,
5536        .cancel_attach = mem_cgroup_cancel_attach,
5537        .attach = mem_cgroup_move_task,
5538        .base_cftypes = mem_cgroup_files,
5539        .early_init = 0,
5540        .use_id = 1,
5541        .__DEPRECATED_clear_css_refs = true,
5542};
5543
5544#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
5545static int __init enable_swap_account(char *s)
5546{
5547        /* consider enabled if no parameter or 1 is given */
5548        if (!strcmp(s, "1"))
5549                really_do_swap_account = 1;
5550        else if (!strcmp(s, "0"))
5551                really_do_swap_account = 0;
5552        return 1;
5553}
5554__setup("swapaccount=", enable_swap_account);
5555
5556#endif
5557
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