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_MEMCG_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_MEMCG_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_SWAP, /* # 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_ANON,
 382        MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
 383        MEM_CGROUP_CHARGE_TYPE_DROP,    /* a page was unused swap cache */
 384        NR_CHARGE_TYPE,
 385};
 386
 387/* for encoding cft->private value on file */
 388#define _MEM                    (0)
 389#define _MEMSWAP                (1)
 390#define _OOM_TYPE               (2)
 391#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
 392#define MEMFILE_TYPE(val)       ((val) >> 16 & 0xffff)
 393#define MEMFILE_ATTR(val)       ((val) & 0xffff)
 394/* Used for OOM nofiier */
 395#define OOM_CONTROL             (0)
 396
 397/*
 398 * Reclaim flags for mem_cgroup_hierarchical_reclaim
 399 */
 400#define MEM_CGROUP_RECLAIM_NOSWAP_BIT   0x0
 401#define MEM_CGROUP_RECLAIM_NOSWAP       (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
 402#define MEM_CGROUP_RECLAIM_SHRINK_BIT   0x1
 403#define MEM_CGROUP_RECLAIM_SHRINK       (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
 404
 405static void mem_cgroup_get(struct mem_cgroup *memcg);
 406static void mem_cgroup_put(struct mem_cgroup *memcg);
 407
 408static inline
 409struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
 410{
 411        return container_of(s, struct mem_cgroup, css);
 412}
 413
 414/* Writing them here to avoid exposing memcg's inner layout */
 415#ifdef CONFIG_MEMCG_KMEM
 416#include <net/sock.h>
 417#include <net/ip.h>
 418
 419static bool mem_cgroup_is_root(struct mem_cgroup *memcg);
 420void sock_update_memcg(struct sock *sk)
 421{
 422        if (mem_cgroup_sockets_enabled) {
 423                struct mem_cgroup *memcg;
 424                struct cg_proto *cg_proto;
 425
 426                BUG_ON(!sk->sk_prot->proto_cgroup);
 427
 428                /* Socket cloning can throw us here with sk_cgrp already
 429                 * filled. It won't however, necessarily happen from
 430                 * process context. So the test for root memcg given
 431                 * the current task's memcg won't help us in this case.
 432                 *
 433                 * Respecting the original socket's memcg is a better
 434                 * decision in this case.
 435                 */
 436                if (sk->sk_cgrp) {
 437                        BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
 438                        mem_cgroup_get(sk->sk_cgrp->memcg);
 439                        return;
 440                }
 441
 442                rcu_read_lock();
 443                memcg = mem_cgroup_from_task(current);
 444                cg_proto = sk->sk_prot->proto_cgroup(memcg);
 445                if (!mem_cgroup_is_root(memcg) && memcg_proto_active(cg_proto)) {
 446                        mem_cgroup_get(memcg);
 447                        sk->sk_cgrp = cg_proto;
 448                }
 449                rcu_read_unlock();
 450        }
 451}
 452EXPORT_SYMBOL(sock_update_memcg);
 453
 454void sock_release_memcg(struct sock *sk)
 455{
 456        if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
 457                struct mem_cgroup *memcg;
 458                WARN_ON(!sk->sk_cgrp->memcg);
 459                memcg = sk->sk_cgrp->memcg;
 460                mem_cgroup_put(memcg);
 461        }
 462}
 463
 464#ifdef CONFIG_INET
 465struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
 466{
 467        if (!memcg || mem_cgroup_is_root(memcg))
 468                return NULL;
 469
 470        return &memcg->tcp_mem.cg_proto;
 471}
 472EXPORT_SYMBOL(tcp_proto_cgroup);
 473#endif /* CONFIG_INET */
 474#endif /* CONFIG_MEMCG_KMEM */
 475
 476#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
 477static void disarm_sock_keys(struct mem_cgroup *memcg)
 478{
 479        if (!memcg_proto_activated(&memcg->tcp_mem.cg_proto))
 480                return;
 481        static_key_slow_dec(&memcg_socket_limit_enabled);
 482}
 483#else
 484static void disarm_sock_keys(struct mem_cgroup *memcg)
 485{
 486}
 487#endif
 488
 489static void drain_all_stock_async(struct mem_cgroup *memcg);
 490
 491static struct mem_cgroup_per_zone *
 492mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
 493{
 494        return &memcg->info.nodeinfo[nid]->zoneinfo[zid];
 495}
 496
 497struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
 498{
 499        return &memcg->css;
 500}
 501
 502static struct mem_cgroup_per_zone *
 503page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
 504{
 505        int nid = page_to_nid(page);
 506        int zid = page_zonenum(page);
 507
 508        return mem_cgroup_zoneinfo(memcg, nid, zid);
 509}
 510
 511static struct mem_cgroup_tree_per_zone *
 512soft_limit_tree_node_zone(int nid, int zid)
 513{
 514        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
 515}
 516
 517static struct mem_cgroup_tree_per_zone *
 518soft_limit_tree_from_page(struct page *page)
 519{
 520        int nid = page_to_nid(page);
 521        int zid = page_zonenum(page);
 522
 523        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
 524}
 525
 526static void
 527__mem_cgroup_insert_exceeded(struct mem_cgroup *memcg,
 528                                struct mem_cgroup_per_zone *mz,
 529                                struct mem_cgroup_tree_per_zone *mctz,
 530                                unsigned long long new_usage_in_excess)
 531{
 532        struct rb_node **p = &mctz->rb_root.rb_node;
 533        struct rb_node *parent = NULL;
 534        struct mem_cgroup_per_zone *mz_node;
 535
 536        if (mz->on_tree)
 537                return;
 538
 539        mz->usage_in_excess = new_usage_in_excess;
 540        if (!mz->usage_in_excess)
 541                return;
 542        while (*p) {
 543                parent = *p;
 544                mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
 545                                        tree_node);
 546                if (mz->usage_in_excess < mz_node->usage_in_excess)
 547                        p = &(*p)->rb_left;
 548                /*
 549                 * We can't avoid mem cgroups that are over their soft
 550                 * limit by the same amount
 551                 */
 552                else if (mz->usage_in_excess >= mz_node->usage_in_excess)
 553                        p = &(*p)->rb_right;
 554        }
 555        rb_link_node(&mz->tree_node, parent, p);
 556        rb_insert_color(&mz->tree_node, &mctz->rb_root);
 557        mz->on_tree = true;
 558}
 559
 560static void
 561__mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
 562                                struct mem_cgroup_per_zone *mz,
 563                                struct mem_cgroup_tree_per_zone *mctz)
 564{
 565        if (!mz->on_tree)
 566                return;
 567        rb_erase(&mz->tree_node, &mctz->rb_root);
 568        mz->on_tree = false;
 569}
 570
 571static void
 572mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
 573                                struct mem_cgroup_per_zone *mz,
 574                                struct mem_cgroup_tree_per_zone *mctz)
 575{
 576        spin_lock(&mctz->lock);
 577        __mem_cgroup_remove_exceeded(memcg, mz, mctz);
 578        spin_unlock(&mctz->lock);
 579}
 580
 581
 582static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
 583{
 584        unsigned long long excess;
 585        struct mem_cgroup_per_zone *mz;
 586        struct mem_cgroup_tree_per_zone *mctz;
 587        int nid = page_to_nid(page);
 588        int zid = page_zonenum(page);
 589        mctz = soft_limit_tree_from_page(page);
 590
 591        /*
 592         * Necessary to update all ancestors when hierarchy is used.
 593         * because their event counter is not touched.
 594         */
 595        for (; memcg; memcg = parent_mem_cgroup(memcg)) {
 596                mz = mem_cgroup_zoneinfo(memcg, nid, zid);
 597                excess = res_counter_soft_limit_excess(&memcg->res);
 598                /*
 599                 * We have to update the tree if mz is on RB-tree or
 600                 * mem is over its softlimit.
 601                 */
 602                if (excess || mz->on_tree) {
 603                        spin_lock(&mctz->lock);
 604                        /* if on-tree, remove it */
 605                        if (mz->on_tree)
 606                                __mem_cgroup_remove_exceeded(memcg, mz, mctz);
 607                        /*
 608                         * Insert again. mz->usage_in_excess will be updated.
 609                         * If excess is 0, no tree ops.
 610                         */
 611                        __mem_cgroup_insert_exceeded(memcg, mz, mctz, excess);
 612                        spin_unlock(&mctz->lock);
 613                }
 614        }
 615}
 616
 617static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
 618{
 619        int node, zone;
 620        struct mem_cgroup_per_zone *mz;
 621        struct mem_cgroup_tree_per_zone *mctz;
 622
 623        for_each_node(node) {
 624                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
 625                        mz = mem_cgroup_zoneinfo(memcg, node, zone);
 626                        mctz = soft_limit_tree_node_zone(node, zone);
 627                        mem_cgroup_remove_exceeded(memcg, mz, mctz);
 628                }
 629        }
 630}
 631
 632static struct mem_cgroup_per_zone *
 633__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 634{
 635        struct rb_node *rightmost = NULL;
 636        struct mem_cgroup_per_zone *mz;
 637
 638retry:
 639        mz = NULL;
 640        rightmost = rb_last(&mctz->rb_root);
 641        if (!rightmost)
 642                goto done;              /* Nothing to reclaim from */
 643
 644        mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
 645        /*
 646         * Remove the node now but someone else can add it back,
 647         * we will to add it back at the end of reclaim to its correct
 648         * position in the tree.
 649         */
 650        __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
 651        if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
 652                !css_tryget(&mz->memcg->css))
 653                goto retry;
 654done:
 655        return mz;
 656}
 657
 658static struct mem_cgroup_per_zone *
 659mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 660{
 661        struct mem_cgroup_per_zone *mz;
 662
 663        spin_lock(&mctz->lock);
 664        mz = __mem_cgroup_largest_soft_limit_node(mctz);
 665        spin_unlock(&mctz->lock);
 666        return mz;
 667}
 668
 669/*
 670 * Implementation Note: reading percpu statistics for memcg.
 671 *
 672 * Both of vmstat[] and percpu_counter has threshold and do periodic
 673 * synchronization to implement "quick" read. There are trade-off between
 674 * reading cost and precision of value. Then, we may have a chance to implement
 675 * a periodic synchronizion of counter in memcg's counter.
 676 *
 677 * But this _read() function is used for user interface now. The user accounts
 678 * memory usage by memory cgroup and he _always_ requires exact value because
 679 * he accounts memory. Even if we provide quick-and-fuzzy read, we always
 680 * have to visit all online cpus and make sum. So, for now, unnecessary
 681 * synchronization is not implemented. (just implemented for cpu hotplug)
 682 *
 683 * If there are kernel internal actions which can make use of some not-exact
 684 * value, and reading all cpu value can be performance bottleneck in some
 685 * common workload, threashold and synchonization as vmstat[] should be
 686 * implemented.
 687 */
 688static long mem_cgroup_read_stat(struct mem_cgroup *memcg,
 689                                 enum mem_cgroup_stat_index idx)
 690{
 691        long val = 0;
 692        int cpu;
 693
 694        get_online_cpus();
 695        for_each_online_cpu(cpu)
 696                val += per_cpu(memcg->stat->count[idx], cpu);
 697#ifdef CONFIG_HOTPLUG_CPU
 698        spin_lock(&memcg->pcp_counter_lock);
 699        val += memcg->nocpu_base.count[idx];
 700        spin_unlock(&memcg->pcp_counter_lock);
 701#endif
 702        put_online_cpus();
 703        return val;
 704}
 705
 706static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
 707                                         bool charge)
 708{
 709        int val = (charge) ? 1 : -1;
 710        this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val);
 711}
 712
 713static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
 714                                            enum mem_cgroup_events_index idx)
 715{
 716        unsigned long val = 0;
 717        int cpu;
 718
 719        for_each_online_cpu(cpu)
 720                val += per_cpu(memcg->stat->events[idx], cpu);
 721#ifdef CONFIG_HOTPLUG_CPU
 722        spin_lock(&memcg->pcp_counter_lock);
 723        val += memcg->nocpu_base.events[idx];
 724        spin_unlock(&memcg->pcp_counter_lock);
 725#endif
 726        return val;
 727}
 728
 729static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
 730                                         bool anon, int nr_pages)
 731{
 732        preempt_disable();
 733
 734        /*
 735         * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
 736         * counted as CACHE even if it's on ANON LRU.
 737         */
 738        if (anon)
 739                __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
 740                                nr_pages);
 741        else
 742                __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
 743                                nr_pages);
 744
 745        /* pagein of a big page is an event. So, ignore page size */
 746        if (nr_pages > 0)
 747                __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
 748        else {
 749                __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
 750                nr_pages = -nr_pages; /* for event */
 751        }
 752
 753        __this_cpu_add(memcg->stat->nr_page_events, nr_pages);
 754
 755        preempt_enable();
 756}
 757
 758unsigned long
 759mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
 760{
 761        struct mem_cgroup_per_zone *mz;
 762
 763        mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
 764        return mz->lru_size[lru];
 765}
 766
 767static unsigned long
 768mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
 769                        unsigned int lru_mask)
 770{
 771        struct mem_cgroup_per_zone *mz;
 772        enum lru_list lru;
 773        unsigned long ret = 0;
 774
 775        mz = mem_cgroup_zoneinfo(memcg, nid, zid);
 776
 777        for_each_lru(lru) {
 778                if (BIT(lru) & lru_mask)
 779                        ret += mz->lru_size[lru];
 780        }
 781        return ret;
 782}
 783
 784static unsigned long
 785mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
 786                        int nid, unsigned int lru_mask)
 787{
 788        u64 total = 0;
 789        int zid;
 790
 791        for (zid = 0; zid < MAX_NR_ZONES; zid++)
 792                total += mem_cgroup_zone_nr_lru_pages(memcg,
 793                                                nid, zid, lru_mask);
 794
 795        return total;
 796}
 797
 798static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
 799                        unsigned int lru_mask)
 800{
 801        int nid;
 802        u64 total = 0;
 803
 804        for_each_node_state(nid, N_HIGH_MEMORY)
 805                total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
 806        return total;
 807}
 808
 809static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
 810                                       enum mem_cgroup_events_target target)
 811{
 812        unsigned long val, next;
 813
 814        val = __this_cpu_read(memcg->stat->nr_page_events);
 815        next = __this_cpu_read(memcg->stat->targets[target]);
 816        /* from time_after() in jiffies.h */
 817        if ((long)next - (long)val < 0) {
 818                switch (target) {
 819                case MEM_CGROUP_TARGET_THRESH:
 820                        next = val + THRESHOLDS_EVENTS_TARGET;
 821                        break;
 822                case MEM_CGROUP_TARGET_SOFTLIMIT:
 823                        next = val + SOFTLIMIT_EVENTS_TARGET;
 824                        break;
 825                case MEM_CGROUP_TARGET_NUMAINFO:
 826                        next = val + NUMAINFO_EVENTS_TARGET;
 827                        break;
 828                default:
 829                        break;
 830                }
 831                __this_cpu_write(memcg->stat->targets[target], next);
 832                return true;
 833        }
 834        return false;
 835}
 836
 837/*
 838 * Check events in order.
 839 *
 840 */
 841static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
 842{
 843        preempt_disable();
 844        /* threshold event is triggered in finer grain than soft limit */
 845        if (unlikely(mem_cgroup_event_ratelimit(memcg,
 846                                                MEM_CGROUP_TARGET_THRESH))) {
 847                bool do_softlimit;
 848                bool do_numainfo __maybe_unused;
 849
 850                do_softlimit = mem_cgroup_event_ratelimit(memcg,
 851                                                MEM_CGROUP_TARGET_SOFTLIMIT);
 852#if MAX_NUMNODES > 1
 853                do_numainfo = mem_cgroup_event_ratelimit(memcg,
 854                                                MEM_CGROUP_TARGET_NUMAINFO);
 855#endif
 856                preempt_enable();
 857
 858                mem_cgroup_threshold(memcg);
 859                if (unlikely(do_softlimit))
 860                        mem_cgroup_update_tree(memcg, page);
 861#if MAX_NUMNODES > 1
 862                if (unlikely(do_numainfo))
 863                        atomic_inc(&memcg->numainfo_events);
 864#endif
 865        } else
 866                preempt_enable();
 867}
 868
 869struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 870{
 871        return mem_cgroup_from_css(
 872                cgroup_subsys_state(cont, mem_cgroup_subsys_id));
 873}
 874
 875struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 876{
 877        /*
 878         * mm_update_next_owner() may clear mm->owner to NULL
 879         * if it races with swapoff, page migration, etc.
 880         * So this can be called with p == NULL.
 881         */
 882        if (unlikely(!p))
 883                return NULL;
 884
 885        return mem_cgroup_from_css(task_subsys_state(p, mem_cgroup_subsys_id));
 886}
 887
 888struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 889{
 890        struct mem_cgroup *memcg = NULL;
 891
 892        if (!mm)
 893                return NULL;
 894        /*
 895         * Because we have no locks, mm->owner's may be being moved to other
 896         * cgroup. We use css_tryget() here even if this looks
 897         * pessimistic (rather than adding locks here).
 898         */
 899        rcu_read_lock();
 900        do {
 901                memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
 902                if (unlikely(!memcg))
 903                        break;
 904        } while (!css_tryget(&memcg->css));
 905        rcu_read_unlock();
 906        return memcg;
 907}
 908
 909/**
 910 * mem_cgroup_iter - iterate over memory cgroup hierarchy
 911 * @root: hierarchy root
 912 * @prev: previously returned memcg, NULL on first invocation
 913 * @reclaim: cookie for shared reclaim walks, NULL for full walks
 914 *
 915 * Returns references to children of the hierarchy below @root, or
 916 * @root itself, or %NULL after a full round-trip.
 917 *
 918 * Caller must pass the return value in @prev on subsequent
 919 * invocations for reference counting, or use mem_cgroup_iter_break()
 920 * to cancel a hierarchy walk before the round-trip is complete.
 921 *
 922 * Reclaimers can specify a zone and a priority level in @reclaim to
 923 * divide up the memcgs in the hierarchy among all concurrent
 924 * reclaimers operating on the same zone and priority.
 925 */
 926struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 927                                   struct mem_cgroup *prev,
 928                                   struct mem_cgroup_reclaim_cookie *reclaim)
 929{
 930        struct mem_cgroup *memcg = NULL;
 931        int id = 0;
 932
 933        if (mem_cgroup_disabled())
 934                return NULL;
 935
 936        if (!root)
 937                root = root_mem_cgroup;
 938
 939        if (prev && !reclaim)
 940                id = css_id(&prev->css);
 941
 942        if (prev && prev != root)
 943                css_put(&prev->css);
 944
 945        if (!root->use_hierarchy && root != root_mem_cgroup) {
 946                if (prev)
 947                        return NULL;
 948                return root;
 949        }
 950
 951        while (!memcg) {
 952                struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
 953                struct cgroup_subsys_state *css;
 954
 955                if (reclaim) {
 956                        int nid = zone_to_nid(reclaim->zone);
 957                        int zid = zone_idx(reclaim->zone);
 958                        struct mem_cgroup_per_zone *mz;
 959
 960                        mz = mem_cgroup_zoneinfo(root, nid, zid);
 961                        iter = &mz->reclaim_iter[reclaim->priority];
 962                        if (prev && reclaim->generation != iter->generation)
 963                                return NULL;
 964                        id = iter->position;
 965                }
 966
 967                rcu_read_lock();
 968                css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
 969                if (css) {
 970                        if (css == &root->css || css_tryget(css))
 971                                memcg = mem_cgroup_from_css(css);
 972                } else
 973                        id = 0;
 974                rcu_read_unlock();
 975
 976                if (reclaim) {
 977                        iter->position = id;
 978                        if (!css)
 979                                iter->generation++;
 980                        else if (!prev && memcg)
 981                                reclaim->generation = iter->generation;
 982                }
 983
 984                if (prev && !css)
 985                        return NULL;
 986        }
 987        return memcg;
 988}
 989
 990/**
 991 * mem_cgroup_iter_break - abort a hierarchy walk prematurely
 992 * @root: hierarchy root
 993 * @prev: last visited hierarchy member as returned by mem_cgroup_iter()
 994 */
 995void mem_cgroup_iter_break(struct mem_cgroup *root,
 996                           struct mem_cgroup *prev)
 997{
 998        if (!root)
 999                root = root_mem_cgroup;
1000        if (prev && prev != root)
1001                css_put(&prev->css);
1002}
1003
1004/*
1005 * Iteration constructs for visiting all cgroups (under a tree).  If
1006 * loops are exited prematurely (break), mem_cgroup_iter_break() must
1007 * be used for reference counting.
1008 */
1009#define for_each_mem_cgroup_tree(iter, root)            \
1010        for (iter = mem_cgroup_iter(root, NULL, NULL);  \
1011             iter != NULL;                              \
1012             iter = mem_cgroup_iter(root, iter, NULL))
1013
1014#define for_each_mem_cgroup(iter)                       \
1015        for (iter = mem_cgroup_iter(NULL, NULL, NULL);  \
1016             iter != NULL;                              \
1017             iter = mem_cgroup_iter(NULL, iter, NULL))
1018
1019static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
1020{
1021        return (memcg == root_mem_cgroup);
1022}
1023
1024void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
1025{
1026        struct mem_cgroup *memcg;
1027
1028        if (!mm)
1029                return;
1030
1031        rcu_read_lock();
1032        memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
1033        if (unlikely(!memcg))
1034                goto out;
1035
1036        switch (idx) {
1037        case PGFAULT:
1038                this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
1039                break;
1040        case PGMAJFAULT:
1041                this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
1042                break;
1043        default:
1044                BUG();
1045        }
1046out:
1047        rcu_read_unlock();
1048}
1049EXPORT_SYMBOL(mem_cgroup_count_vm_event);
1050
1051/**
1052 * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
1053 * @zone: zone of the wanted lruvec
1054 * @memcg: memcg of the wanted lruvec
1055 *
1056 * Returns the lru list vector holding pages for the given @zone and
1057 * @mem.  This can be the global zone lruvec, if the memory controller
1058 * is disabled.
1059 */
1060struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
1061                                      struct mem_cgroup *memcg)
1062{
1063        struct mem_cgroup_per_zone *mz;
1064
1065        if (mem_cgroup_disabled())
1066                return &zone->lruvec;
1067
1068        mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
1069        return &mz->lruvec;
1070}
1071
1072/*
1073 * Following LRU functions are allowed to be used without PCG_LOCK.
1074 * Operations are called by routine of global LRU independently from memcg.
1075 * What we have to take care of here is validness of pc->mem_cgroup.
1076 *
1077 * Changes to pc->mem_cgroup happens when
1078 * 1. charge
1079 * 2. moving account
1080 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
1081 * It is added to LRU before charge.
1082 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
1083 * When moving account, the page is not on LRU. It's isolated.
1084 */
1085
1086/**
1087 * mem_cgroup_page_lruvec - return lruvec for adding an lru page
1088 * @page: the page
1089 * @zone: zone of the page
1090 */
1091struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
1092{
1093        struct mem_cgroup_per_zone *mz;
1094        struct mem_cgroup *memcg;
1095        struct page_cgroup *pc;
1096
1097        if (mem_cgroup_disabled())
1098                return &zone->lruvec;
1099
1100        pc = lookup_page_cgroup(page);
1101        memcg = pc->mem_cgroup;
1102
1103        /*
1104         * Surreptitiously switch any uncharged offlist page to root:
1105         * an uncharged page off lru does nothing to secure
1106         * its former mem_cgroup from sudden removal.
1107         *
1108         * Our caller holds lru_lock, and PageCgroupUsed is updated
1109         * under page_cgroup lock: between them, they make all uses
1110         * of pc->mem_cgroup safe.
1111         */
1112        if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup)
1113                pc->mem_cgroup = memcg = root_mem_cgroup;
1114
1115        mz = page_cgroup_zoneinfo(memcg, page);
1116        return &mz->lruvec;
1117}
1118
1119/**
1120 * mem_cgroup_update_lru_size - account for adding or removing an lru page
1121 * @lruvec: mem_cgroup per zone lru vector
1122 * @lru: index of lru list the page is sitting on
1123 * @nr_pages: positive when adding or negative when removing
1124 *
1125 * This function must be called when a page is added to or removed from an
1126 * lru list.
1127 */
1128void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
1129                                int nr_pages)
1130{
1131        struct mem_cgroup_per_zone *mz;
1132        unsigned long *lru_size;
1133
1134        if (mem_cgroup_disabled())
1135                return;
1136
1137        mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
1138        lru_size = mz->lru_size + lru;
1139        *lru_size += nr_pages;
1140        VM_BUG_ON((long)(*lru_size) < 0);
1141}
1142
1143/*
1144 * Checks whether given mem is same or in the root_mem_cgroup's
1145 * hierarchy subtree
1146 */
1147bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
1148                                  struct mem_cgroup *memcg)
1149{
1150        if (root_memcg == memcg)
1151                return true;
1152        if (!root_memcg->use_hierarchy || !memcg)
1153                return false;
1154        return css_is_ancestor(&memcg->css, &root_memcg->css);
1155}
1156
1157static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
1158                                       struct mem_cgroup *memcg)
1159{
1160        bool ret;
1161
1162        rcu_read_lock();
1163        ret = __mem_cgroup_same_or_subtree(root_memcg, memcg);
1164        rcu_read_unlock();
1165        return ret;
1166}
1167
1168int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
1169{
1170        int ret;
1171        struct mem_cgroup *curr = NULL;
1172        struct task_struct *p;
1173
1174        p = find_lock_task_mm(task);
1175        if (p) {
1176                curr = try_get_mem_cgroup_from_mm(p->mm);
1177                task_unlock(p);
1178        } else {
1179                /*
1180                 * All threads may have already detached their mm's, but the oom
1181                 * killer still needs to detect if they have already been oom
1182                 * killed to prevent needlessly killing additional tasks.
1183                 */
1184                task_lock(task);
1185                curr = mem_cgroup_from_task(task);
1186                if (curr)
1187                        css_get(&curr->css);
1188                task_unlock(task);
1189        }
1190        if (!curr)
1191                return 0;
1192        /*
1193         * We should check use_hierarchy of "memcg" not "curr". Because checking
1194         * use_hierarchy of "curr" here make this function true if hierarchy is
1195         * enabled in "curr" and "curr" is a child of "memcg" in *cgroup*
1196         * hierarchy(even if use_hierarchy is disabled in "memcg").
1197         */
1198        ret = mem_cgroup_same_or_subtree(memcg, curr);
1199        css_put(&curr->css);
1200        return ret;
1201}
1202
1203int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
1204{
1205        unsigned long inactive_ratio;
1206        unsigned long inactive;
1207        unsigned long active;
1208        unsigned long gb;
1209
1210        inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
1211        active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);
1212
1213        gb = (inactive + active) >> (30 - PAGE_SHIFT);
1214        if (gb)
1215                inactive_ratio = int_sqrt(10 * gb);
1216        else
1217                inactive_ratio = 1;
1218
1219        return inactive * inactive_ratio < active;
1220}
1221
1222int mem_cgroup_inactive_file_is_low(struct lruvec *lruvec)
1223{
1224        unsigned long active;
1225        unsigned long inactive;
1226
1227        inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_FILE);
1228        active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_FILE);
1229
1230        return (active > inactive);
1231}
1232
1233#define mem_cgroup_from_res_counter(counter, member)    \
1234        container_of(counter, struct mem_cgroup, member)
1235
1236/**
1237 * mem_cgroup_margin - calculate chargeable space of a memory cgroup
1238 * @memcg: the memory cgroup
1239 *
1240 * Returns the maximum amount of memory @mem can be charged with, in
1241 * pages.
1242 */
1243static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
1244{
1245        unsigned long long margin;
1246
1247        margin = res_counter_margin(&memcg->res);
1248        if (do_swap_account)
1249                margin = min(margin, res_counter_margin(&memcg->memsw));
1250        return margin >> PAGE_SHIFT;
1251}
1252
1253int mem_cgroup_swappiness(struct mem_cgroup *memcg)
1254{
1255        struct cgroup *cgrp = memcg->css.cgroup;
1256
1257        /* root ? */
1258        if (cgrp->parent == NULL)
1259                return vm_swappiness;
1260
1261        return memcg->swappiness;
1262}
1263
1264/*
1265 * memcg->moving_account is used for checking possibility that some thread is
1266 * calling move_account(). When a thread on CPU-A starts moving pages under
1267 * a memcg, other threads should check memcg->moving_account under
1268 * rcu_read_lock(), like this:
1269 *
1270 *         CPU-A                                    CPU-B
1271 *                                              rcu_read_lock()
1272 *         memcg->moving_account+1              if (memcg->mocing_account)
1273 *                                                   take heavy locks.
1274 *         synchronize_rcu()                    update something.
1275 *                                              rcu_read_unlock()
1276 *         start move here.
1277 */
1278
1279/* for quick checking without looking up memcg */
1280atomic_t memcg_moving __read_mostly;
1281
1282static void mem_cgroup_start_move(struct mem_cgroup *memcg)
1283{
1284        atomic_inc(&memcg_moving);
1285        atomic_inc(&memcg->moving_account);
1286        synchronize_rcu();
1287}
1288
1289static void mem_cgroup_end_move(struct mem_cgroup *memcg)
1290{
1291        /*
1292         * Now, mem_cgroup_clear_mc() may call this function with NULL.
1293         * We check NULL in callee rather than caller.
1294         */
1295        if (memcg) {
1296                atomic_dec(&memcg_moving);
1297                atomic_dec(&memcg->moving_account);
1298        }
1299}
1300
1301/*
1302 * 2 routines for checking "mem" is under move_account() or not.
1303 *
1304 * mem_cgroup_stolen() -  checking whether a cgroup is mc.from or not. This
1305 *                        is used for avoiding races in accounting.  If true,
1306 *                        pc->mem_cgroup may be overwritten.
1307 *
1308 * mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
1309 *                        under hierarchy of moving cgroups. This is for
1310 *                        waiting at hith-memory prressure caused by "move".
1311 */
1312
1313static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
1314{
1315        VM_BUG_ON(!rcu_read_lock_held());
1316        return atomic_read(&memcg->moving_account) > 0;
1317}
1318
1319static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
1320{
1321        struct mem_cgroup *from;
1322        struct mem_cgroup *to;
1323        bool ret = false;
1324        /*
1325         * Unlike task_move routines, we access mc.to, mc.from not under
1326         * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
1327         */
1328        spin_lock(&mc.lock);
1329        from = mc.from;
1330        to = mc.to;
1331        if (!from)
1332                goto unlock;
1333
1334        ret = mem_cgroup_same_or_subtree(memcg, from)
1335                || mem_cgroup_same_or_subtree(memcg, to);
1336unlock:
1337        spin_unlock(&mc.lock);
1338        return ret;
1339}
1340
1341static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
1342{
1343        if (mc.moving_task && current != mc.moving_task) {
1344                if (mem_cgroup_under_move(memcg)) {
1345                        DEFINE_WAIT(wait);
1346                        prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
1347                        /* moving charge context might have finished. */
1348                        if (mc.moving_task)
1349                                schedule();
1350                        finish_wait(&mc.waitq, &wait);
1351                        return true;
1352                }
1353        }
1354        return false;
1355}
1356
1357/*
1358 * Take this lock when
1359 * - a code tries to modify page's memcg while it's USED.
1360 * - a code tries to modify page state accounting in a memcg.
1361 * see mem_cgroup_stolen(), too.
1362 */
1363static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
1364                                  unsigned long *flags)
1365{
1366        spin_lock_irqsave(&memcg->move_lock, *flags);
1367}
1368
1369static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
1370                                unsigned long *flags)
1371{
1372        spin_unlock_irqrestore(&memcg->move_lock, *flags);
1373}
1374
1375/**
1376 * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
1377 * @memcg: The memory cgroup that went over limit
1378 * @p: Task that is going to be killed
1379 *
1380 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1381 * enabled
1382 */
1383void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
1384{
1385        struct cgroup *task_cgrp;
1386        struct cgroup *mem_cgrp;
1387        /*
1388         * Need a buffer in BSS, can't rely on allocations. The code relies
1389         * on the assumption that OOM is serialized for memory controller.
1390         * If this assumption is broken, revisit this code.
1391         */
1392        static char memcg_name[PATH_MAX];
1393        int ret;
1394
1395        if (!memcg || !p)
1396                return;
1397
1398        rcu_read_lock();
1399
1400        mem_cgrp = memcg->css.cgroup;
1401        task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
1402
1403        ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
1404        if (ret < 0) {
1405                /*
1406                 * Unfortunately, we are unable to convert to a useful name
1407                 * But we'll still print out the usage information
1408                 */
1409                rcu_read_unlock();
1410                goto done;
1411        }
1412        rcu_read_unlock();
1413
1414        printk(KERN_INFO "Task in %s killed", memcg_name);
1415
1416        rcu_read_lock();
1417        ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
1418        if (ret < 0) {
1419                rcu_read_unlock();
1420                goto done;
1421        }
1422        rcu_read_unlock();
1423
1424        /*
1425         * Continues from above, so we don't need an KERN_ level
1426         */
1427        printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
1428done:
1429
1430        printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
1431                res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
1432                res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
1433                res_counter_read_u64(&memcg->res, RES_FAILCNT));
1434        printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
1435                "failcnt %llu\n",
1436                res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
1437                res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
1438                res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
1439}
1440
1441/*
1442 * This function returns the number of memcg under hierarchy tree. Returns
1443 * 1(self count) if no children.
1444 */
1445static int mem_cgroup_count_children(struct mem_cgroup *memcg)
1446{
1447        int num = 0;
1448        struct mem_cgroup *iter;
1449
1450        for_each_mem_cgroup_tree(iter, memcg)
1451                num++;
1452        return num;
1453}
1454
1455/*
1456 * Return the memory (and swap, if configured) limit for a memcg.
1457 */
1458static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
1459{
1460        u64 limit;
1461        u64 memsw;
1462
1463        limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
1464        limit += total_swap_pages << PAGE_SHIFT;
1465
1466        memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1467        /*
1468         * If memsw is finite and limits the amount of swap space available
1469         * to this memcg, return that limit.
1470         */
1471        return min(limit, memsw);
1472}
1473
1474void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
1475                              int order)
1476{
1477        struct mem_cgroup *iter;
1478        unsigned long chosen_points = 0;
1479        unsigned long totalpages;
1480        unsigned int points = 0;
1481        struct task_struct *chosen = NULL;
1482
1483        /*
1484         * If current has a pending SIGKILL, then automatically select it.  The
1485         * goal is to allow it to allocate so that it may quickly exit and free
1486         * its memory.
1487         */
1488        if (fatal_signal_pending(current)) {
1489                set_thread_flag(TIF_MEMDIE);
1490                return;
1491        }
1492
1493        check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
1494        totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
1495        for_each_mem_cgroup_tree(iter, memcg) {
1496                struct cgroup *cgroup = iter->css.cgroup;
1497                struct cgroup_iter it;
1498                struct task_struct *task;
1499
1500                cgroup_iter_start(cgroup, &it);
1501                while ((task = cgroup_iter_next(cgroup, &it))) {
1502                        switch (oom_scan_process_thread(task, totalpages, NULL,
1503                                                        false)) {
1504                        case OOM_SCAN_SELECT:
1505                                if (chosen)
1506                                        put_task_struct(chosen);
1507                                chosen = task;
1508                                chosen_points = ULONG_MAX;
1509                                get_task_struct(chosen);
1510                                /* fall through */
1511                        case OOM_SCAN_CONTINUE:
1512                                continue;
1513                        case OOM_SCAN_ABORT:
1514                                cgroup_iter_end(cgroup, &it);
1515                                mem_cgroup_iter_break(memcg, iter);
1516                                if (chosen)
1517                                        put_task_struct(chosen);
1518                                return;
1519                        case OOM_SCAN_OK:
1520                                break;
1521                        };
1522                        points = oom_badness(task, memcg, NULL, totalpages);
1523                        if (points > chosen_points) {
1524                                if (chosen)
1525                                        put_task_struct(chosen);
1526                                chosen = task;
1527                                chosen_points = points;
1528                                get_task_struct(chosen);
1529                        }
1530                }
1531                cgroup_iter_end(cgroup, &it);
1532        }
1533
1534        if (!chosen)
1535                return;
1536        points = chosen_points * 1000 / totalpages;
1537        oom_kill_process(chosen, gfp_mask, order, points, totalpages, memcg,
1538                         NULL, "Memory cgroup out of memory");
1539}
1540
1541static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg,
1542                                        gfp_t gfp_mask,
1543                                        unsigned long flags)
1544{
1545        unsigned long total = 0;
1546        bool noswap = false;
1547        int loop;
1548
1549        if (flags & MEM_CGROUP_RECLAIM_NOSWAP)
1550                noswap = true;
1551        if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum)
1552                noswap = true;
1553
1554        for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) {
1555                if (loop)
1556                        drain_all_stock_async(memcg);
1557                total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap);
1558                /*
1559                 * Allow limit shrinkers, which are triggered directly
1560                 * by userspace, to catch signals and stop reclaim
1561                 * after minimal progress, regardless of the margin.
1562                 */
1563                if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK))
1564                        break;
1565                if (mem_cgroup_margin(memcg))
1566                        break;
1567                /*
1568                 * If nothing was reclaimed after two attempts, there
1569                 * may be no reclaimable pages in this hierarchy.
1570                 */
1571                if (loop && !total)
1572                        break;
1573        }
1574        return total;
1575}
1576
1577/**
1578 * test_mem_cgroup_node_reclaimable
1579 * @memcg: the target memcg
1580 * @nid: the node ID to be checked.
1581 * @noswap : specify true here if the user wants flle only information.
1582 *
1583 * This function returns whether the specified memcg contains any
1584 * reclaimable pages on a node. Returns true if there are any reclaimable
1585 * pages in the node.
1586 */
1587static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
1588                int nid, bool noswap)
1589{
1590        if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
1591                return true;
1592        if (noswap || !total_swap_pages)
1593                return false;
1594        if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
1595                return true;
1596        return false;
1597
1598}
1599#if MAX_NUMNODES > 1
1600
1601/*
1602 * Always updating the nodemask is not very good - even if we have an empty
1603 * list or the wrong list here, we can start from some node and traverse all
1604 * nodes based on the zonelist. So update the list loosely once per 10 secs.
1605 *
1606 */
1607static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
1608{
1609        int nid;
1610        /*
1611         * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
1612         * pagein/pageout changes since the last update.
1613         */
1614        if (!atomic_read(&memcg->numainfo_events))
1615                return;
1616        if (atomic_inc_return(&memcg->numainfo_updating) > 1)
1617                return;
1618
1619        /* make a nodemask where this memcg uses memory from */
1620        memcg->scan_nodes = node_states[N_HIGH_MEMORY];
1621
1622        for_each_node_mask(nid, node_states[N_HIGH_MEMORY]) {
1623
1624                if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
1625                        node_clear(nid, memcg->scan_nodes);
1626        }
1627
1628        atomic_set(&memcg->numainfo_events, 0);
1629        atomic_set(&memcg->numainfo_updating, 0);
1630}
1631
1632/*
1633 * Selecting a node where we start reclaim from. Because what we need is just
1634 * reducing usage counter, start from anywhere is O,K. Considering
1635 * memory reclaim from current node, there are pros. and cons.
1636 *
1637 * Freeing memory from current node means freeing memory from a node which
1638 * we'll use or we've used. So, it may make LRU bad. And if several threads
1639 * hit limits, it will see a contention on a node. But freeing from remote
1640 * node means more costs for memory reclaim because of memory latency.
1641 *
1642 * Now, we use round-robin. Better algorithm is welcomed.
1643 */
1644int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
1645{
1646        int node;
1647
1648        mem_cgroup_may_update_nodemask(memcg);
1649        node = memcg->last_scanned_node;
1650
1651        node = next_node(node, memcg->scan_nodes);
1652        if (node == MAX_NUMNODES)
1653                node = first_node(memcg->scan_nodes);
1654        /*
1655         * We call this when we hit limit, not when pages are added to LRU.
1656         * No LRU may hold pages because all pages are UNEVICTABLE or
1657         * memcg is too small and all pages are not on LRU. In that case,
1658         * we use curret node.
1659         */
1660        if (unlikely(node == MAX_NUMNODES))
1661                node = numa_node_id();
1662
1663        memcg->last_scanned_node = node;
1664        return node;
1665}
1666
1667/*
1668 * Check all nodes whether it contains reclaimable pages or not.
1669 * For quick scan, we make use of scan_nodes. This will allow us to skip
1670 * unused nodes. But scan_nodes is lazily updated and may not cotain
1671 * enough new information. We need to do double check.
1672 */
1673static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
1674{
1675        int nid;
1676
1677        /*
1678         * quick check...making use of scan_node.
1679         * We can skip unused nodes.
1680         */
1681        if (!nodes_empty(memcg->scan_nodes)) {
1682                for (nid = first_node(memcg->scan_nodes);
1683                     nid < MAX_NUMNODES;
1684                     nid = next_node(nid, memcg->scan_nodes)) {
1685
1686                        if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
1687                                return true;
1688                }
1689        }
1690        /*
1691         * Check rest of nodes.
1692         */
1693        for_each_node_state(nid, N_HIGH_MEMORY) {
1694                if (node_isset(nid, memcg->scan_nodes))
1695                        continue;
1696                if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
1697                        return true;
1698        }
1699        return false;
1700}
1701
1702#else
1703int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
1704{
1705        return 0;
1706}
1707
1708static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
1709{
1710        return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
1711}
1712#endif
1713
1714static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
1715                                   struct zone *zone,
1716                                   gfp_t gfp_mask,
1717                                   unsigned long *total_scanned)
1718{
1719        struct mem_cgroup *victim = NULL;
1720        int total = 0;
1721        int loop = 0;
1722        unsigned long excess;
1723        unsigned long nr_scanned;
1724        struct mem_cgroup_reclaim_cookie reclaim = {
1725                .zone = zone,
1726                .priority = 0,
1727        };
1728
1729        excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
1730
1731        while (1) {
1732                victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
1733                if (!victim) {
1734                        loop++;
1735                        if (loop >= 2) {
1736                                /*
1737                                 * If we have not been able to reclaim
1738                                 * anything, it might because there are
1739                                 * no reclaimable pages under this hierarchy
1740                                 */
1741                                if (!total)
1742                                        break;
1743                                /*
1744                                 * We want to do more targeted reclaim.
1745                                 * excess >> 2 is not to excessive so as to
1746                                 * reclaim too much, nor too less that we keep
1747                                 * coming back to reclaim from this cgroup
1748                                 */
1749                                if (total >= (excess >> 2) ||
1750                                        (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
1751                                        break;
1752                        }
1753                        continue;
1754                }
1755                if (!mem_cgroup_reclaimable(victim, false))
1756                        continue;
1757                total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
1758                                                     zone, &nr_scanned);
1759                *total_scanned += nr_scanned;
1760                if (!res_counter_soft_limit_excess(&root_memcg->res))
1761                        break;
1762        }
1763        mem_cgroup_iter_break(root_memcg, victim);
1764        return total;
1765}
1766
1767/*
1768 * Check OOM-Killer is already running under our hierarchy.
1769 * If someone is running, return false.
1770 * Has to be called with memcg_oom_lock
1771 */
1772static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg)
1773{
1774        struct mem_cgroup *iter, *failed = NULL;
1775
1776        for_each_mem_cgroup_tree(iter, memcg) {
1777                if (iter->oom_lock) {
1778                        /*
1779                         * this subtree of our hierarchy is already locked
1780                         * so we cannot give a lock.
1781                         */
1782                        failed = iter;
1783                        mem_cgroup_iter_break(memcg, iter);
1784                        break;
1785                } else
1786                        iter->oom_lock = true;
1787        }
1788
1789        if (!failed)
1790                return true;
1791
1792        /*
1793         * OK, we failed to lock the whole subtree so we have to clean up
1794         * what we set up to the failing subtree
1795         */
1796        for_each_mem_cgroup_tree(iter, memcg) {
1797                if (iter == failed) {
1798                        mem_cgroup_iter_break(memcg, iter);
1799                        break;
1800                }
1801                iter->oom_lock = false;
1802        }
1803        return false;
1804}
1805
1806/*
1807 * Has to be called with memcg_oom_lock
1808 */
1809static int mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
1810{
1811        struct mem_cgroup *iter;
1812
1813        for_each_mem_cgroup_tree(iter, memcg)
1814                iter->oom_lock = false;
1815        return 0;
1816}
1817
1818static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
1819{
1820        struct mem_cgroup *iter;
1821
1822        for_each_mem_cgroup_tree(iter, memcg)
1823                atomic_inc(&iter->under_oom);
1824}
1825
1826static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
1827{
1828        struct mem_cgroup *iter;
1829
1830        /*
1831         * When a new child is created while the hierarchy is under oom,
1832         * mem_cgroup_oom_lock() may not be called. We have to use
1833         * atomic_add_unless() here.
1834         */
1835        for_each_mem_cgroup_tree(iter, memcg)
1836                atomic_add_unless(&iter->under_oom, -1, 0);
1837}
1838
1839static DEFINE_SPINLOCK(memcg_oom_lock);
1840static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1841
1842struct oom_wait_info {
1843        struct mem_cgroup *memcg;
1844        wait_queue_t    wait;
1845};
1846
1847static int memcg_oom_wake_function(wait_queue_t *wait,
1848        unsigned mode, int sync, void *arg)
1849{
1850        struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
1851        struct mem_cgroup *oom_wait_memcg;
1852        struct oom_wait_info *oom_wait_info;
1853
1854        oom_wait_info = container_of(wait, struct oom_wait_info, wait);
1855        oom_wait_memcg = oom_wait_info->memcg;
1856
1857        /*
1858         * Both of oom_wait_info->memcg and wake_memcg are stable under us.
1859         * Then we can use css_is_ancestor without taking care of RCU.
1860         */
1861        if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg)
1862                && !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg))
1863                return 0;
1864        return autoremove_wake_function(wait, mode, sync, arg);
1865}
1866
1867static void memcg_wakeup_oom(struct mem_cgroup *memcg)
1868{
1869        /* for filtering, pass "memcg" as argument. */
1870        __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
1871}
1872
1873static void memcg_oom_recover(struct mem_cgroup *memcg)
1874{
1875        if (memcg && atomic_read(&memcg->under_oom))
1876                memcg_wakeup_oom(memcg);
1877}
1878
1879/*
1880 * try to call OOM killer. returns false if we should exit memory-reclaim loop.
1881 */
1882static bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask,
1883                                  int order)
1884{
1885        struct oom_wait_info owait;
1886        bool locked, need_to_kill;
1887
1888        owait.memcg = memcg;
1889        owait.wait.flags = 0;
1890        owait.wait.func = memcg_oom_wake_function;
1891        owait.wait.private = current;
1892        INIT_LIST_HEAD(&owait.wait.task_list);
1893        need_to_kill = true;
1894        mem_cgroup_mark_under_oom(memcg);
1895
1896        /* At first, try to OOM lock hierarchy under memcg.*/
1897        spin_lock(&memcg_oom_lock);
1898        locked = mem_cgroup_oom_lock(memcg);
1899        /*
1900         * Even if signal_pending(), we can't quit charge() loop without
1901         * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
1902         * under OOM is always welcomed, use TASK_KILLABLE here.
1903         */
1904        prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
1905        if (!locked || memcg->oom_kill_disable)
1906                need_to_kill = false;
1907        if (locked)
1908                mem_cgroup_oom_notify(memcg);
1909        spin_unlock(&memcg_oom_lock);
1910
1911        if (need_to_kill) {
1912                finish_wait(&memcg_oom_waitq, &owait.wait);
1913                mem_cgroup_out_of_memory(memcg, mask, order);
1914        } else {
1915                schedule();
1916                finish_wait(&memcg_oom_waitq, &owait.wait);
1917        }
1918        spin_lock(&memcg_oom_lock);
1919        if (locked)
1920                mem_cgroup_oom_unlock(memcg);
1921        memcg_wakeup_oom(memcg);
1922        spin_unlock(&memcg_oom_lock);
1923
1924        mem_cgroup_unmark_under_oom(memcg);
1925
1926        if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
1927                return false;
1928        /* Give chance to dying process */
1929        schedule_timeout_uninterruptible(1);
1930        return true;
1931}
1932
1933/*
1934 * Currently used to update mapped file statistics, but the routine can be
1935 * generalized to update other statistics as well.
1936 *
1937 * Notes: Race condition
1938 *
1939 * We usually use page_cgroup_lock() for accessing page_cgroup member but
1940 * it tends to be costly. But considering some conditions, we doesn't need
1941 * to do so _always_.
1942 *
1943 * Considering "charge", lock_page_cgroup() is not required because all
1944 * file-stat operations happen after a page is attached to radix-tree. There
1945 * are no race with "charge".
1946 *
1947 * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
1948 * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
1949 * if there are race with "uncharge". Statistics itself is properly handled
1950 * by flags.
1951 *
1952 * Considering "move", this is an only case we see a race. To make the race
1953 * small, we check mm->moving_account and detect there are possibility of race
1954 * If there is, we take a lock.
1955 */
1956
1957void __mem_cgroup_begin_update_page_stat(struct page *page,
1958                                bool *locked, unsigned long *flags)
1959{
1960        struct mem_cgroup *memcg;
1961        struct page_cgroup *pc;
1962
1963        pc = lookup_page_cgroup(page);
1964again:
1965        memcg = pc->mem_cgroup;
1966        if (unlikely(!memcg || !PageCgroupUsed(pc)))
1967                return;
1968        /*
1969         * If this memory cgroup is not under account moving, we don't
1970         * need to take move_lock_mem_cgroup(). Because we already hold
1971         * rcu_read_lock(), any calls to move_account will be delayed until
1972         * rcu_read_unlock() if mem_cgroup_stolen() == true.
1973         */
1974        if (!mem_cgroup_stolen(memcg))
1975                return;
1976
1977        move_lock_mem_cgroup(memcg, flags);
1978        if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
1979                move_unlock_mem_cgroup(memcg, flags);
1980                goto again;
1981        }
1982        *locked = true;
1983}
1984
1985void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
1986{
1987        struct page_cgroup *pc = lookup_page_cgroup(page);
1988
1989        /*
1990         * It's guaranteed that pc->mem_cgroup never changes while
1991         * lock is held because a routine modifies pc->mem_cgroup
1992         * should take move_lock_mem_cgroup().
1993         */
1994        move_unlock_mem_cgroup(pc->mem_cgroup, flags);
1995}
1996
1997void mem_cgroup_update_page_stat(struct page *page,
1998                                 enum mem_cgroup_page_stat_item idx, int val)
1999{
2000        struct mem_cgroup *memcg;
2001        struct page_cgroup *pc = lookup_page_cgroup(page);
2002        unsigned long uninitialized_var(flags);
2003
2004        if (mem_cgroup_disabled())
2005                return;
2006
2007        memcg = pc->mem_cgroup;
2008        if (unlikely(!memcg || !PageCgroupUsed(pc)))
2009                return;
2010
2011        switch (idx) {
2012        case MEMCG_NR_FILE_MAPPED:
2013                idx = MEM_CGROUP_STAT_FILE_MAPPED;
2014                break;
2015        default:
2016                BUG();
2017        }
2018
2019        this_cpu_add(memcg->stat->count[idx], val);
2020}
2021
2022/*
2023 * size of first charge trial. "32" comes from vmscan.c's magic value.
2024 * TODO: maybe necessary to use big numbers in big irons.
2025 */
2026#define CHARGE_BATCH    32U
2027struct memcg_stock_pcp {
2028        struct mem_cgroup *cached; /* this never be root cgroup */
2029        unsigned int nr_pages;
2030        struct work_struct work;
2031        unsigned long flags;
2032#define FLUSHING_CACHED_CHARGE  0
2033};
2034static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
2035static DEFINE_MUTEX(percpu_charge_mutex);
2036
2037/*
2038 * Try to consume stocked charge on this cpu. If success, one page is consumed
2039 * from local stock and true is returned. If the stock is 0 or charges from a
2040 * cgroup which is not current target, returns false. This stock will be
2041 * refilled.
2042 */
2043static bool consume_stock(struct mem_cgroup *memcg)
2044{
2045        struct memcg_stock_pcp *stock;
2046        bool ret = true;
2047
2048        stock = &get_cpu_var(memcg_stock);
2049        if (memcg == stock->cached && stock->nr_pages)
2050                stock->nr_pages--;
2051        else /* need to call res_counter_charge */
2052                ret = false;
2053        put_cpu_var(memcg_stock);
2054        return ret;
2055}
2056
2057/*
2058 * Returns stocks cached in percpu to res_counter and reset cached information.
2059 */
2060static void drain_stock(struct memcg_stock_pcp *stock)
2061{
2062        struct mem_cgroup *old = stock->cached;
2063
2064        if (stock->nr_pages) {
2065                unsigned long bytes = stock->nr_pages * PAGE_SIZE;
2066
2067                res_counter_uncharge(&old->res, bytes);
2068                if (do_swap_account)
2069                        res_counter_uncharge(&old->memsw, bytes);
2070                stock->nr_pages = 0;
2071        }
2072        stock->cached = NULL;
2073}
2074
2075/*
2076 * This must be called under preempt disabled or must be called by
2077 * a thread which is pinned to local cpu.
2078 */
2079static void drain_local_stock(struct work_struct *dummy)
2080{
2081        struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
2082        drain_stock(stock);
2083        clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
2084}
2085
2086/*
2087 * Cache charges(val) which is from res_counter, to local per_cpu area.
2088 * This will be consumed by consume_stock() function, later.
2089 */
2090static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2091{
2092        struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
2093
2094        if (stock->cached != memcg) { /* reset if necessary */
2095                drain_stock(stock);
2096                stock->cached = memcg;
2097        }
2098        stock->nr_pages += nr_pages;
2099        put_cpu_var(memcg_stock);
2100}
2101
2102/*
2103 * Drains all per-CPU charge caches for given root_memcg resp. subtree
2104 * of the hierarchy under it. sync flag says whether we should block
2105 * until the work is done.
2106 */
2107static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
2108{
2109        int cpu, curcpu;
2110
2111        /* Notify other cpus that system-wide "drain" is running */
2112        get_online_cpus();
2113        curcpu = get_cpu();
2114        for_each_online_cpu(cpu) {
2115                struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2116                struct mem_cgroup *memcg;
2117
2118                memcg = stock->cached;
2119                if (!memcg || !stock->nr_pages)
2120                        continue;
2121                if (!mem_cgroup_same_or_subtree(root_memcg, memcg))
2122                        continue;
2123                if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
2124                        if (cpu == curcpu)
2125                                drain_local_stock(&stock->work);
2126                        else
2127                                schedule_work_on(cpu, &stock->work);
2128                }
2129        }
2130        put_cpu();
2131
2132        if (!sync)
2133                goto out;
2134
2135        for_each_online_cpu(cpu) {
2136                struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2137                if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
2138                        flush_work(&stock->work);
2139        }
2140out:
2141        put_online_cpus();
2142}
2143
2144/*
2145 * Tries to drain stocked charges in other cpus. This function is asynchronous
2146 * and just put a work per cpu for draining localy on each cpu. Caller can
2147 * expects some charges will be back to res_counter later but cannot wait for
2148 * it.
2149 */
2150static void drain_all_stock_async(struct mem_cgroup *root_memcg)
2151{
2152        /*
2153         * If someone calls draining, avoid adding more kworker runs.
2154         */
2155        if (!mutex_trylock(&percpu_charge_mutex))
2156                return;
2157        drain_all_stock(root_memcg, false);
2158        mutex_unlock(&percpu_charge_mutex);
2159}
2160
2161/* This is a synchronous drain interface. */
2162static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
2163{
2164        /* called when force_empty is called */
2165        mutex_lock(&percpu_charge_mutex);
2166        drain_all_stock(root_memcg, true);
2167        mutex_unlock(&percpu_charge_mutex);
2168}
2169
2170/*
2171 * This function drains percpu counter value from DEAD cpu and
2172 * move it to local cpu. Note that this function can be preempted.
2173 */
2174static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu)
2175{
2176        int i;
2177
2178        spin_lock(&memcg->pcp_counter_lock);
2179        for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
2180                long x = per_cpu(memcg->stat->count[i], cpu);
2181
2182                per_cpu(memcg->stat->count[i], cpu) = 0;
2183                memcg->nocpu_base.count[i] += x;
2184        }
2185        for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
2186                unsigned long x = per_cpu(memcg->stat->events[i], cpu);
2187
2188                per_cpu(memcg->stat->events[i], cpu) = 0;
2189                memcg->nocpu_base.events[i] += x;
2190        }
2191        spin_unlock(&memcg->pcp_counter_lock);
2192}
2193
2194static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb,
2195                                        unsigned long action,
2196                                        void *hcpu)
2197{
2198        int cpu = (unsigned long)hcpu;
2199        struct memcg_stock_pcp *stock;
2200        struct mem_cgroup *iter;
2201
2202        if (action == CPU_ONLINE)
2203                return NOTIFY_OK;
2204
2205        if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
2206                return NOTIFY_OK;
2207
2208        for_each_mem_cgroup(iter)
2209                mem_cgroup_drain_pcp_counter(iter, cpu);
2210
2211        stock = &per_cpu(memcg_stock, cpu);
2212        drain_stock(stock);
2213        return NOTIFY_OK;
2214}
2215
2216
2217/* See __mem_cgroup_try_charge() for details */
2218enum {
2219        CHARGE_OK,              /* success */
2220        CHARGE_RETRY,           /* need to retry but retry is not bad */
2221        CHARGE_NOMEM,           /* we can't do more. return -ENOMEM */
2222        CHARGE_WOULDBLOCK,      /* GFP_WAIT wasn't set and no enough res. */
2223        CHARGE_OOM_DIE,         /* the current is killed because of OOM */
2224};
2225
2226static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
2227                                unsigned int nr_pages, bool oom_check)
2228{
2229        unsigned long csize = nr_pages * PAGE_SIZE;
2230        struct mem_cgroup *mem_over_limit;
2231        struct res_counter *fail_res;
2232        unsigned long flags = 0;
2233        int ret;
2234
2235        ret = res_counter_charge(&memcg->res, csize, &fail_res);
2236
2237        if (likely(!ret)) {
2238                if (!do_swap_account)
2239                        return CHARGE_OK;
2240                ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
2241                if (likely(!ret))
2242                        return CHARGE_OK;
2243
2244                res_counter_uncharge(&memcg->res, csize);
2245                mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
2246                flags |= MEM_CGROUP_RECLAIM_NOSWAP;
2247        } else
2248                mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
2249        /*
2250         * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch
2251         * of regular pages (CHARGE_BATCH), or a single regular page (1).
2252         *
2253         * Never reclaim on behalf of optional batching, retry with a
2254         * single page instead.
2255         */
2256        if (nr_pages == CHARGE_BATCH)
2257                return CHARGE_RETRY;
2258
2259        if (!(gfp_mask & __GFP_WAIT))
2260                return CHARGE_WOULDBLOCK;
2261
2262        ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
2263        if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
2264                return CHARGE_RETRY;
2265        /*
2266         * Even though the limit is exceeded at this point, reclaim
2267         * may have been able to free some pages.  Retry the charge
2268         * before killing the task.
2269         *
2270         * Only for regular pages, though: huge pages are rather
2271         * unlikely to succeed so close to the limit, and we fall back
2272         * to regular pages anyway in case of failure.
2273         */
2274        if (nr_pages == 1 && ret)
2275                return CHARGE_RETRY;
2276
2277        /*
2278         * At task move, charge accounts can be doubly counted. So, it's
2279         * better to wait until the end of task_move if something is going on.
2280         */
2281        if (mem_cgroup_wait_acct_move(mem_over_limit))
2282                return CHARGE_RETRY;
2283
2284        /* If we don't need to call oom-killer at el, return immediately */
2285        if (!oom_check)
2286                return CHARGE_NOMEM;
2287        /* check OOM */
2288        if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize)))
2289                return CHARGE_OOM_DIE;
2290
2291        return CHARGE_RETRY;
2292}
2293
2294/*
2295 * __mem_cgroup_try_charge() does
2296 * 1. detect memcg to be charged against from passed *mm and *ptr,
2297 * 2. update res_counter
2298 * 3. call memory reclaim if necessary.
2299 *
2300 * In some special case, if the task is fatal, fatal_signal_pending() or
2301 * has TIF_MEMDIE, this function returns -EINTR while writing root_mem_cgroup
2302 * to *ptr. There are two reasons for this. 1: fatal threads should quit as soon
2303 * as possible without any hazards. 2: all pages should have a valid
2304 * pc->mem_cgroup. If mm is NULL and the caller doesn't pass a valid memcg
2305 * pointer, that is treated as a charge to root_mem_cgroup.
2306 *
2307 * So __mem_cgroup_try_charge() will return
2308 *  0       ...  on success, filling *ptr with a valid memcg pointer.
2309 *  -ENOMEM ...  charge failure because of resource limits.
2310 *  -EINTR  ...  if thread is fatal. *ptr is filled with root_mem_cgroup.
2311 *
2312 * Unlike the exported interface, an "oom" parameter is added. if oom==true,
2313 * the oom-killer can be invoked.
2314 */
2315static int __mem_cgroup_try_charge(struct mm_struct *mm,
2316                                   gfp_t gfp_mask,
2317                                   unsigned int nr_pages,
2318                                   struct mem_cgroup **ptr,
2319                                   bool oom)
2320{
2321        unsigned int batch = max(CHARGE_BATCH, nr_pages);
2322        int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
2323        struct mem_cgroup *memcg = NULL;
2324        int ret;
2325
2326        /*
2327         * Unlike gloval-vm's OOM-kill, we're not in memory shortage
2328         * in system level. So, allow to go ahead dying process in addition to
2329         * MEMDIE process.
2330         */
2331        if (unlikely(test_thread_flag(TIF_MEMDIE)
2332                     || fatal_signal_pending(current)))
2333                goto bypass;
2334
2335        /*
2336         * We always charge the cgroup the mm_struct belongs to.
2337         * The mm_struct's mem_cgroup changes on task migration if the
2338         * thread group leader migrates. It's possible that mm is not
2339         * set, if so charge the root memcg (happens for pagecache usage).
2340         */
2341        if (!*ptr && !mm)
2342                *ptr = root_mem_cgroup;
2343again:
2344        if (*ptr) { /* css should be a valid one */
2345                memcg = *ptr;
2346                VM_BUG_ON(css_is_removed(&memcg->css));
2347                if (mem_cgroup_is_root(memcg))
2348                        goto done;
2349                if (nr_pages == 1 && consume_stock(memcg))
2350                        goto done;
2351                css_get(&memcg->css);
2352        } else {
2353                struct task_struct *p;
2354
2355                rcu_read_lock();
2356                p = rcu_dereference(mm->owner);
2357                /*
2358                 * Because we don't have task_lock(), "p" can exit.
2359                 * In that case, "memcg" can point to root or p can be NULL with
2360                 * race with swapoff. Then, we have small risk of mis-accouning.
2361                 * But such kind of mis-account by race always happens because
2362                 * we don't have cgroup_mutex(). It's overkill and we allo that
2363                 * small race, here.
2364                 * (*) swapoff at el will charge against mm-struct not against
2365                 * task-struct. So, mm->owner can be NULL.
2366                 */
2367                memcg = mem_cgroup_from_task(p);
2368                if (!memcg)
2369                        memcg = root_mem_cgroup;
2370                if (mem_cgroup_is_root(memcg)) {
2371                        rcu_read_unlock();
2372                        goto done;
2373                }
2374                if (nr_pages == 1 && consume_stock(memcg)) {
2375                        /*
2376                         * It seems dagerous to access memcg without css_get().
2377                         * But considering how consume_stok works, it's not
2378                         * necessary. If consume_stock success, some charges
2379                         * from this memcg are cached on this cpu. So, we
2380                         * don't need to call css_get()/css_tryget() before
2381                         * calling consume_stock().
2382                         */
2383                        rcu_read_unlock();
2384                        goto done;
2385                }
2386                /* after here, we may be blocked. we need to get refcnt */
2387                if (!css_tryget(&memcg->css)) {
2388                        rcu_read_unlock();
2389                        goto again;
2390                }
2391                rcu_read_unlock();
2392        }
2393
2394        do {
2395                bool oom_check;
2396
2397                /* If killed, bypass charge */
2398                if (fatal_signal_pending(current)) {
2399                        css_put(&memcg->css);
2400                        goto bypass;
2401                }
2402
2403                oom_check = false;
2404                if (oom && !nr_oom_retries) {
2405                        oom_check = true;
2406                        nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
2407                }
2408
2409                ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check);
2410                switch (ret) {
2411                case CHARGE_OK:
2412                        break;
2413                case CHARGE_RETRY: /* not in OOM situation but retry */
2414                        batch = nr_pages;
2415                        css_put(&memcg->css);
2416                        memcg = NULL;
2417                        goto again;
2418                case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
2419                        css_put(&memcg->css);
2420                        goto nomem;
2421                case CHARGE_NOMEM: /* OOM routine works */
2422                        if (!oom) {
2423                                css_put(&memcg->css);
2424                                goto nomem;
2425                        }
2426                        /* If oom, we never return -ENOMEM */
2427                        nr_oom_retries--;
2428                        break;
2429                case CHARGE_OOM_DIE: /* Killed by OOM Killer */
2430                        css_put(&memcg->css);
2431                        goto bypass;
2432                }
2433        } while (ret != CHARGE_OK);
2434
2435        if (batch > nr_pages)
2436                refill_stock(memcg, batch - nr_pages);
2437        css_put(&memcg->css);
2438done:
2439        *ptr = memcg;
2440        return 0;
2441nomem:
2442        *ptr = NULL;
2443        return -ENOMEM;
2444bypass:
2445        *ptr = root_mem_cgroup;
2446        return -EINTR;
2447}
2448
2449/*
2450 * Somemtimes we have to undo a charge we got by try_charge().
2451 * This function is for that and do uncharge, put css's refcnt.
2452 * gotten by try_charge().
2453 */
2454static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
2455                                       unsigned int nr_pages)
2456{
2457        if (!mem_cgroup_is_root(memcg)) {
2458                unsigned long bytes = nr_pages * PAGE_SIZE;
2459
2460                res_counter_uncharge(&memcg->res, bytes);
2461                if (do_swap_account)
2462                        res_counter_uncharge(&memcg->memsw, bytes);
2463        }
2464}
2465
2466/*
2467 * Cancel chrages in this cgroup....doesn't propagate to parent cgroup.
2468 * This is useful when moving usage to parent cgroup.
2469 */
2470static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
2471                                        unsigned int nr_pages)
2472{
2473        unsigned long bytes = nr_pages * PAGE_SIZE;
2474
2475        if (mem_cgroup_is_root(memcg))
2476                return;
2477
2478        res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
2479        if (do_swap_account)
2480                res_counter_uncharge_until(&memcg->memsw,
2481                                                memcg->memsw.parent, bytes);
2482}
2483
2484/*
2485 * A helper function to get mem_cgroup from ID. must be called under
2486 * rcu_read_lock(). The caller must check css_is_removed() or some if
2487 * it's concern. (dropping refcnt from swap can be called against removed
2488 * memcg.)
2489 */
2490static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
2491{
2492        struct cgroup_subsys_state *css;
2493
2494        /* ID 0 is unused ID */
2495        if (!id)
2496                return NULL;
2497        css = css_lookup(&mem_cgroup_subsys, id);
2498        if (!css)
2499                return NULL;
2500        return mem_cgroup_from_css(css);
2501}
2502
2503struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
2504{
2505        struct mem_cgroup *memcg = NULL;
2506        struct page_cgroup *pc;
2507        unsigned short id;
2508        swp_entry_t ent;
2509
2510        VM_BUG_ON(!PageLocked(page));
2511
2512        pc = lookup_page_cgroup(page);
2513        lock_page_cgroup(pc);
2514        if (PageCgroupUsed(pc)) {
2515                memcg = pc->mem_cgroup;
2516                if (memcg && !css_tryget(&memcg->css))
2517                        memcg = NULL;
2518        } else if (PageSwapCache(page)) {
2519                ent.val = page_private(page);
2520                id = lookup_swap_cgroup_id(ent);
2521                rcu_read_lock();
2522                memcg = mem_cgroup_lookup(id);
2523                if (memcg && !css_tryget(&memcg->css))
2524                        memcg = NULL;
2525                rcu_read_unlock();
2526        }
2527        unlock_page_cgroup(pc);
2528        return memcg;
2529}
2530
2531static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
2532                                       struct page *page,
2533                                       unsigned int nr_pages,
2534                                       enum charge_type ctype,
2535                                       bool lrucare)
2536{
2537        struct page_cgroup *pc = lookup_page_cgroup(page);
2538        struct zone *uninitialized_var(zone);
2539        struct lruvec *lruvec;
2540        bool was_on_lru = false;
2541        bool anon;
2542
2543        lock_page_cgroup(pc);
2544        VM_BUG_ON(PageCgroupUsed(pc));
2545        /*
2546         * we don't need page_cgroup_lock about tail pages, becase they are not
2547         * accessed by any other context at this point.
2548         */
2549
2550        /*
2551         * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
2552         * may already be on some other mem_cgroup's LRU.  Take care of it.
2553         */
2554        if (lrucare) {
2555                zone = page_zone(page);
2556                spin_lock_irq(&zone->lru_lock);
2557                if (PageLRU(page)) {
2558                        lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2559                        ClearPageLRU(page);
2560                        del_page_from_lru_list(page, lruvec, page_lru(page));
2561                        was_on_lru = true;
2562                }
2563        }
2564
2565        pc->mem_cgroup = memcg;
2566        /*
2567         * We access a page_cgroup asynchronously without lock_page_cgroup().
2568         * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
2569         * is accessed after testing USED bit. To make pc->mem_cgroup visible
2570         * before USED bit, we need memory barrier here.
2571         * See mem_cgroup_add_lru_list(), etc.
2572         */
2573        smp_wmb();
2574        SetPageCgroupUsed(pc);
2575
2576        if (lrucare) {
2577                if (was_on_lru) {
2578                        lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup);
2579                        VM_BUG_ON(PageLRU(page));
2580                        SetPageLRU(page);
2581                        add_page_to_lru_list(page, lruvec, page_lru(page));
2582                }
2583                spin_unlock_irq(&zone->lru_lock);
2584        }
2585
2586        if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON)
2587                anon = true;
2588        else
2589                anon = false;
2590
2591        mem_cgroup_charge_statistics(memcg, anon, nr_pages);
2592        unlock_page_cgroup(pc);
2593
2594        /*
2595         * "charge_statistics" updated event counter. Then, check it.
2596         * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
2597         * if they exceeds softlimit.
2598         */
2599        memcg_check_events(memcg, page);
2600}
2601
2602#ifdef CONFIG_TRANSPARENT_HUGEPAGE
2603
2604#define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION)
2605/*
2606 * Because tail pages are not marked as "used", set it. We're under
2607 * zone->lru_lock, 'splitting on pmd' and compound_lock.
2608 * charge/uncharge will be never happen and move_account() is done under
2609 * compound_lock(), so we don't have to take care of races.
2610 */
2611void mem_cgroup_split_huge_fixup(struct page *head)
2612{
2613        struct page_cgroup *head_pc = lookup_page_cgroup(head);
2614        struct page_cgroup *pc;
2615        int i;
2616
2617        if (mem_cgroup_disabled())
2618                return;
2619        for (i = 1; i < HPAGE_PMD_NR; i++) {
2620                pc = head_pc + i;
2621                pc->mem_cgroup = head_pc->mem_cgroup;
2622                smp_wmb();/* see __commit_charge() */
2623                pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
2624        }
2625}
2626#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
2627
2628/**
2629 * mem_cgroup_move_account - move account of the page
2630 * @page: the page
2631 * @nr_pages: number of regular pages (>1 for huge pages)
2632 * @pc: page_cgroup of the page.
2633 * @from: mem_cgroup which the page is moved from.
2634 * @to: mem_cgroup which the page is moved to. @from != @to.
2635 *
2636 * The caller must confirm following.
2637 * - page is not on LRU (isolate_page() is useful.)
2638 * - compound_lock is held when nr_pages > 1
2639 *
2640 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
2641 * from old cgroup.
2642 */
2643static int mem_cgroup_move_account(struct page *page,
2644                                   unsigned int nr_pages,
2645                                   struct page_cgroup *pc,
2646                                   struct mem_cgroup *from,
2647                                   struct mem_cgroup *to)
2648{
2649        unsigned long flags;
2650        int ret;
2651        bool anon = PageAnon(page);
2652
2653        VM_BUG_ON(from == to);
2654        VM_BUG_ON(PageLRU(page));
2655        /*
2656         * The page is isolated from LRU. So, collapse function
2657         * will not handle this page. But page splitting can happen.
2658         * Do this check under compound_page_lock(). The caller should
2659         * hold it.
2660         */
2661        ret = -EBUSY;
2662        if (nr_pages > 1 && !PageTransHuge(page))
2663                goto out;
2664
2665        lock_page_cgroup(pc);
2666
2667        ret = -EINVAL;
2668        if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
2669                goto unlock;
2670
2671        move_lock_mem_cgroup(from, &flags);
2672
2673        if (!anon && page_mapped(page)) {
2674                /* Update mapped_file data for mem_cgroup */
2675                preempt_disable();
2676                __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
2677                __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
2678                preempt_enable();
2679        }
2680        mem_cgroup_charge_statistics(from, anon, -nr_pages);
2681
2682        /* caller should have done css_get */
2683        pc->mem_cgroup = to;
2684        mem_cgroup_charge_statistics(to, anon, nr_pages);
2685        /*
2686         * We charges against "to" which may not have any tasks. Then, "to"
2687         * can be under rmdir(). But in current implementation, caller of
2688         * this function is just force_empty() and move charge, so it's
2689         * guaranteed that "to" is never removed. So, we don't check rmdir
2690         * status here.
2691         */
2692        move_unlock_mem_cgroup(from, &flags);
2693        ret = 0;
2694unlock:
2695        unlock_page_cgroup(pc);
2696        /*
2697         * check events
2698         */
2699        memcg_check_events(to, page);
2700        memcg_check_events(from, page);
2701out:
2702        return ret;
2703}
2704
2705/*
2706 * move charges to its parent.
2707 */
2708
2709static int mem_cgroup_move_parent(struct page *page,
2710                                  struct page_cgroup *pc,
2711                                  struct mem_cgroup *child)
2712{
2713        struct mem_cgroup *parent;
2714        unsigned int nr_pages;
2715        unsigned long uninitialized_var(flags);
2716        int ret;
2717
2718        /* Is ROOT ? */
2719        if (mem_cgroup_is_root(child))
2720                return -EINVAL;
2721
2722        ret = -EBUSY;
2723        if (!get_page_unless_zero(page))
2724                goto out;
2725        if (isolate_lru_page(page))
2726                goto put;
2727
2728        nr_pages = hpage_nr_pages(page);
2729
2730        parent = parent_mem_cgroup(child);
2731        /*
2732         * If no parent, move charges to root cgroup.
2733         */
2734        if (!parent)
2735                parent = root_mem_cgroup;
2736
2737        if (nr_pages > 1)
2738                flags = compound_lock_irqsave(page);
2739
2740        ret = mem_cgroup_move_account(page, nr_pages,
2741                                pc, child, parent);
2742        if (!ret)
2743                __mem_cgroup_cancel_local_charge(child, nr_pages);
2744
2745        if (nr_pages > 1)
2746                compound_unlock_irqrestore(page, flags);
2747        putback_lru_page(page);
2748put:
2749        put_page(page);
2750out:
2751        return ret;
2752}
2753
2754/*
2755 * Charge the memory controller for page usage.
2756 * Return
2757 * 0 if the charge was successful
2758 * < 0 if the cgroup is over its limit
2759 */
2760static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
2761                                gfp_t gfp_mask, enum charge_type ctype)
2762{
2763        struct mem_cgroup *memcg = NULL;
2764        unsigned int nr_pages = 1;
2765        bool oom = true;
2766        int ret;
2767
2768        if (PageTransHuge(page)) {
2769                nr_pages <<= compound_order(page);
2770                VM_BUG_ON(!PageTransHuge(page));
2771                /*
2772                 * Never OOM-kill a process for a huge page.  The
2773                 * fault handler will fall back to regular pages.
2774                 */
2775                oom = false;
2776        }
2777
2778        ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
2779        if (ret == -ENOMEM)
2780                return ret;
2781        __mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false);
2782        return 0;
2783}
2784
2785int mem_cgroup_newpage_charge(struct page *page,
2786                              struct mm_struct *mm, gfp_t gfp_mask)
2787{
2788        if (mem_cgroup_disabled())
2789                return 0;
2790        VM_BUG_ON(page_mapped(page));
2791        VM_BUG_ON(page->mapping && !PageAnon(page));
2792        VM_BUG_ON(!mm);
2793        return mem_cgroup_charge_common(page, mm, gfp_mask,
2794                                        MEM_CGROUP_CHARGE_TYPE_ANON);
2795}
2796
2797/*
2798 * While swap-in, try_charge -> commit or cancel, the page is locked.
2799 * And when try_charge() successfully returns, one refcnt to memcg without
2800 * struct page_cgroup is acquired. This refcnt will be consumed by
2801 * "commit()" or removed by "cancel()"
2802 */
2803static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
2804                                          struct page *page,
2805                                          gfp_t mask,
2806                                          struct mem_cgroup **memcgp)
2807{
2808        struct mem_cgroup *memcg;
2809        struct page_cgroup *pc;
2810        int ret;
2811
2812        pc = lookup_page_cgroup(page);
2813        /*
2814         * Every swap fault against a single page tries to charge the
2815         * page, bail as early as possible.  shmem_unuse() encounters
2816         * already charged pages, too.  The USED bit is protected by
2817         * the page lock, which serializes swap cache removal, which
2818         * in turn serializes uncharging.
2819         */
2820        if (PageCgroupUsed(pc))
2821                return 0;
2822        if (!do_swap_account)
2823                goto charge_cur_mm;
2824        memcg = try_get_mem_cgroup_from_page(page);
2825        if (!memcg)
2826                goto charge_cur_mm;
2827        *memcgp = memcg;
2828        ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true);
2829        css_put(&memcg->css);
2830        if (ret == -EINTR)
2831                ret = 0;
2832        return ret;
2833charge_cur_mm:
2834        ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
2835        if (ret == -EINTR)
2836                ret = 0;
2837        return ret;
2838}
2839
2840int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
2841                                 gfp_t gfp_mask, struct mem_cgroup **memcgp)
2842{
2843        *memcgp = NULL;
2844        if (mem_cgroup_disabled())
2845                return 0;
2846        /*
2847         * A racing thread's fault, or swapoff, may have already
2848         * updated the pte, and even removed page from swap cache: in
2849         * those cases unuse_pte()'s pte_same() test will fail; but
2850         * there's also a KSM case which does need to charge the page.
2851         */
2852        if (!PageSwapCache(page)) {
2853                int ret;
2854
2855                ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, memcgp, true);
2856                if (ret == -EINTR)
2857                        ret = 0;
2858                return ret;
2859        }
2860        return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp);
2861}
2862
2863void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
2864{
2865        if (mem_cgroup_disabled())
2866                return;
2867        if (!memcg)
2868                return;
2869        __mem_cgroup_cancel_charge(memcg, 1);
2870}
2871
2872static void
2873__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
2874                                        enum charge_type ctype)
2875{
2876        if (mem_cgroup_disabled())
2877                return;
2878        if (!memcg)
2879                return;
2880        cgroup_exclude_rmdir(&memcg->css);
2881
2882        __mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
2883        /*
2884         * Now swap is on-memory. This means this page may be
2885         * counted both as mem and swap....double count.
2886         * Fix it by uncharging from memsw. Basically, this SwapCache is stable
2887         * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
2888         * may call delete_from_swap_cache() before reach here.
2889         */
2890        if (do_swap_account && PageSwapCache(page)) {
2891                swp_entry_t ent = {.val = page_private(page)};
2892                mem_cgroup_uncharge_swap(ent);
2893        }
2894        /*
2895         * At swapin, we may charge account against cgroup which has no tasks.
2896         * So, rmdir()->pre_destroy() can be called while we do this charge.
2897         * In that case, we need to call pre_destroy() again. check it here.
2898         */
2899        cgroup_release_and_wakeup_rmdir(&memcg->css);
2900}
2901
2902void mem_cgroup_commit_charge_swapin(struct page *page,
2903                                     struct mem_cgroup *memcg)
2904{
2905        __mem_cgroup_commit_charge_swapin(page, memcg,
2906                                          MEM_CGROUP_CHARGE_TYPE_ANON);
2907}
2908
2909int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
2910                                gfp_t gfp_mask)
2911{
2912        struct mem_cgroup *memcg = NULL;
2913        enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
2914        int ret;
2915
2916        if (mem_cgroup_disabled())
2917                return 0;
2918        if (PageCompound(page))
2919                return 0;
2920
2921        if (!PageSwapCache(page))
2922                ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);
2923        else { /* page is swapcache/shmem */
2924                ret = __mem_cgroup_try_charge_swapin(mm, page,
2925                                                     gfp_mask, &memcg);
2926                if (!ret)
2927                        __mem_cgroup_commit_charge_swapin(page, memcg, type);
2928        }
2929        return ret;
2930}
2931
2932static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
2933                                   unsigned int nr_pages,
2934                                   const enum charge_type ctype)
2935{
2936        struct memcg_batch_info *batch = NULL;
2937        bool uncharge_memsw = true;
2938
2939        /* If swapout, usage of swap doesn't decrease */
2940        if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
2941                uncharge_memsw = false;
2942
2943        batch = &current->memcg_batch;
2944        /*
2945         * In usual, we do css_get() when we remember memcg pointer.
2946         * But in this case, we keep res->usage until end of a series of
2947         * uncharges. Then, it's ok to ignore memcg's refcnt.
2948         */
2949        if (!batch->memcg)
2950                batch->memcg = memcg;
2951        /*
2952         * do_batch > 0 when unmapping pages or inode invalidate/truncate.
2953         * In those cases, all pages freed continuously can be expected to be in
2954         * the same cgroup and we have chance to coalesce uncharges.
2955         * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
2956         * because we want to do uncharge as soon as possible.
2957         */
2958
2959        if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
2960                goto direct_uncharge;
2961
2962        if (nr_pages > 1)
2963                goto direct_uncharge;
2964
2965        /*
2966         * In typical case, batch->memcg == mem. This means we can
2967         * merge a series of uncharges to an uncharge of res_counter.
2968         * If not, we uncharge res_counter ony by one.
2969         */
2970        if (batch->memcg != memcg)
2971                goto direct_uncharge;
2972        /* remember freed charge and uncharge it later */
2973        batch->nr_pages++;
2974        if (uncharge_memsw)
2975                batch->memsw_nr_pages++;
2976        return;
2977direct_uncharge:
2978        res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
2979        if (uncharge_memsw)
2980                res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
2981        if (unlikely(batch->memcg != memcg))
2982                memcg_oom_recover(memcg);
2983}
2984
2985/*
2986 * uncharge if !page_mapped(page)
2987 */
2988static struct mem_cgroup *
2989__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
2990                             bool end_migration)
2991{
2992        struct mem_cgroup *memcg = NULL;
2993        unsigned int nr_pages = 1;
2994        struct page_cgroup *pc;
2995        bool anon;
2996
2997        if (mem_cgroup_disabled())
2998                return NULL;
2999
3000        VM_BUG_ON(PageSwapCache(page));
3001
3002        if (PageTransHuge(page)) {
3003                nr_pages <<= compound_order(page);
3004                VM_BUG_ON(!PageTransHuge(page));
3005        }
3006        /*
3007         * Check if our page_cgroup is valid
3008         */
3009        pc = lookup_page_cgroup(page);
3010        if (unlikely(!PageCgroupUsed(pc)))
3011                return NULL;
3012
3013        lock_page_cgroup(pc);
3014
3015        memcg = pc->mem_cgroup;
3016
3017        if (!PageCgroupUsed(pc))
3018                goto unlock_out;
3019
3020        anon = PageAnon(page);
3021
3022        switch (ctype) {
3023        case MEM_CGROUP_CHARGE_TYPE_ANON:
3024                /*
3025                 * Generally PageAnon tells if it's the anon statistics to be
3026                 * updated; but sometimes e.g. mem_cgroup_uncharge_page() is
3027                 * used before page reached the stage of being marked PageAnon.
3028                 */
3029                anon = true;
3030                /* fallthrough */
3031        case MEM_CGROUP_CHARGE_TYPE_DROP:
3032                /* See mem_cgroup_prepare_migration() */
3033                if (page_mapped(page))
3034                        goto unlock_out;
3035                /*
3036                 * Pages under migration may not be uncharged.  But
3037                 * end_migration() /must/ be the one uncharging the
3038                 * unused post-migration page and so it has to call
3039                 * here with the migration bit still set.  See the
3040                 * res_counter handling below.
3041                 */
3042                if (!end_migration && PageCgroupMigration(pc))
3043                        goto unlock_out;
3044                break;
3045        case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
3046                if (!PageAnon(page)) {  /* Shared memory */
3047                        if (page->mapping && !page_is_file_cache(page))
3048                                goto unlock_out;
3049                } else if (page_mapped(page)) /* Anon */
3050                                goto unlock_out;
3051                break;
3052        default:
3053                break;
3054        }
3055
3056        mem_cgroup_charge_statistics(memcg, anon, -nr_pages);
3057
3058        ClearPageCgroupUsed(pc);
3059        /*
3060         * pc->mem_cgroup is not cleared here. It will be accessed when it's
3061         * freed from LRU. This is safe because uncharged page is expected not
3062         * to be reused (freed soon). Exception is SwapCache, it's handled by
3063         * special functions.
3064         */
3065
3066        unlock_page_cgroup(pc);
3067        /*
3068         * even after unlock, we have memcg->res.usage here and this memcg
3069         * will never be freed.
3070         */
3071        memcg_check_events(memcg, page);
3072        if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
3073                mem_cgroup_swap_statistics(memcg, true);
3074                mem_cgroup_get(memcg);
3075        }
3076        /*
3077         * Migration does not charge the res_counter for the
3078         * replacement page, so leave it alone when phasing out the
3079         * page that is unused after the migration.
3080         */
3081        if (!end_migration && !mem_cgroup_is_root(memcg))
3082                mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
3083
3084        return memcg;
3085
3086unlock_out:
3087        unlock_page_cgroup(pc);
3088        return NULL;
3089}
3090
3091void mem_cgroup_uncharge_page(struct page *page)
3092{
3093        /* early check. */
3094        if (page_mapped(page))
3095                return;
3096        VM_BUG_ON(page->mapping && !PageAnon(page));
3097        if (PageSwapCache(page))
3098                return;
3099        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
3100}
3101
3102void mem_cgroup_uncharge_cache_page(struct page *page)
3103{
3104        VM_BUG_ON(page_mapped(page));
3105        VM_BUG_ON(page->mapping);
3106        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
3107}
3108
3109/*
3110 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
3111 * In that cases, pages are freed continuously and we can expect pages
3112 * are in the same memcg. All these calls itself limits the number of
3113 * pages freed at once, then uncharge_start/end() is called properly.
3114 * This may be called prural(2) times in a context,
3115 */
3116
3117void mem_cgroup_uncharge_start(void)
3118{
3119        current->memcg_batch.do_batch++;
3120        /* We can do nest. */
3121        if (current->memcg_batch.do_batch == 1) {
3122                current->memcg_batch.memcg = NULL;
3123                current->memcg_batch.nr_pages = 0;
3124                current->memcg_batch.memsw_nr_pages = 0;
3125        }
3126}
3127
3128void mem_cgroup_uncharge_end(void)
3129{
3130        struct memcg_batch_info *batch = &current->memcg_batch;
3131
3132        if (!batch->do_batch)
3133                return;
3134
3135        batch->do_batch--;
3136        if (batch->do_batch) /* If stacked, do nothing. */
3137                return;
3138
3139        if (!batch->memcg)
3140                return;
3141        /*
3142         * This "batch->memcg" is valid without any css_get/put etc...
3143         * bacause we hide charges behind us.
3144         */
3145        if (batch->nr_pages)
3146                res_counter_uncharge(&batch->memcg->res,
3147                                     batch->nr_pages * PAGE_SIZE);
3148        if (batch->memsw_nr_pages)
3149                res_counter_uncharge(&batch->memcg->memsw,
3150                                     batch->memsw_nr_pages * PAGE_SIZE);
3151        memcg_oom_recover(batch->memcg);
3152        /* forget this pointer (for sanity check) */
3153        batch->memcg = NULL;
3154}
3155
3156#ifdef CONFIG_SWAP
3157/*
3158 * called after __delete_from_swap_cache() and drop "page" account.
3159 * memcg information is recorded to swap_cgroup of "ent"
3160 */
3161void
3162mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
3163{
3164        struct mem_cgroup *memcg;
3165        int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
3166
3167        if (!swapout) /* this was a swap cache but the swap is unused ! */
3168                ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
3169
3170        memcg = __mem_cgroup_uncharge_common(page, ctype, false);
3171
3172        /*
3173         * record memcg information,  if swapout && memcg != NULL,
3174         * mem_cgroup_get() was called in uncharge().
3175         */
3176        if (do_swap_account && swapout && memcg)
3177                swap_cgroup_record(ent, css_id(&memcg->css));
3178}
3179#endif
3180
3181#ifdef CONFIG_MEMCG_SWAP
3182/*
3183 * called from swap_entry_free(). remove record in swap_cgroup and
3184 * uncharge "memsw" account.
3185 */
3186void mem_cgroup_uncharge_swap(swp_entry_t ent)
3187{
3188        struct mem_cgroup *memcg;
3189        unsigned short id;
3190
3191        if (!do_swap_account)
3192                return;
3193
3194        id = swap_cgroup_record(ent, 0);
3195        rcu_read_lock();
3196        memcg = mem_cgroup_lookup(id);
3197        if (memcg) {
3198                /*
3199                 * We uncharge this because swap is freed.
3200                 * This memcg can be obsolete one. We avoid calling css_tryget
3201                 */
3202                if (!mem_cgroup_is_root(memcg))
3203                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
3204                mem_cgroup_swap_statistics(memcg, false);
3205                mem_cgroup_put(memcg);
3206        }
3207        rcu_read_unlock();
3208}
3209
3210/**
3211 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
3212 * @entry: swap entry to be moved
3213 * @from:  mem_cgroup which the entry is moved from
3214 * @to:  mem_cgroup which the entry is moved to
3215 *
3216 * It succeeds only when the swap_cgroup's record for this entry is the same
3217 * as the mem_cgroup's id of @from.
3218 *
3219 * Returns 0 on success, -EINVAL on failure.
3220 *
3221 * The caller must have charged to @to, IOW, called res_counter_charge() about
3222 * both res and memsw, and called css_get().
3223 */
3224static int mem_cgroup_move_swap_account(swp_entry_t entry,
3225                                struct mem_cgroup *from, struct mem_cgroup *to)
3226{
3227        unsigned short old_id, new_id;
3228
3229        old_id = css_id(&from->css);
3230        new_id = css_id(&to->css);
3231
3232        if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
3233                mem_cgroup_swap_statistics(from, false);
3234                mem_cgroup_swap_statistics(to, true);
3235                /*
3236                 * This function is only called from task migration context now.
3237                 * It postpones res_counter and refcount handling till the end
3238                 * of task migration(mem_cgroup_clear_mc()) for performance
3239                 * improvement. But we cannot postpone mem_cgroup_get(to)
3240                 * because if the process that has been moved to @to does
3241                 * swap-in, the refcount of @to might be decreased to 0.
3242                 */
3243                mem_cgroup_get(to);
3244                return 0;
3245        }
3246        return -EINVAL;
3247}
3248#else
3249static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
3250                                struct mem_cgroup *from, struct mem_cgroup *to)
3251{
3252        return -EINVAL;
3253}
3254#endif
3255
3256/*
3257 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
3258 * page belongs to.
3259 */
3260void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
3261                                  struct mem_cgroup **memcgp)
3262{
3263        struct mem_cgroup *memcg = NULL;
3264        struct page_cgroup *pc;
3265        enum charge_type ctype;
3266
3267        *memcgp = NULL;
3268
3269        VM_BUG_ON(PageTransHuge(page));
3270        if (mem_cgroup_disabled())
3271                return;
3272
3273        pc = lookup_page_cgroup(page);
3274        lock_page_cgroup(pc);
3275        if (PageCgroupUsed(pc)) {
3276                memcg = pc->mem_cgroup;
3277                css_get(&memcg->css);
3278                /*
3279                 * At migrating an anonymous page, its mapcount goes down
3280                 * to 0 and uncharge() will be called. But, even if it's fully
3281                 * unmapped, migration may fail and this page has to be
3282                 * charged again. We set MIGRATION flag here and delay uncharge
3283                 * until end_migration() is called
3284                 *
3285                 * Corner Case Thinking
3286                 * A)
3287                 * When the old page was mapped as Anon and it's unmap-and-freed
3288                 * while migration was ongoing.
3289                 * If unmap finds the old page, uncharge() of it will be delayed
3290                 * until end_migration(). If unmap finds a new page, it's
3291                 * uncharged when it make mapcount to be 1->0. If unmap code
3292                 * finds swap_migration_entry, the new page will not be mapped
3293                 * and end_migration() will find it(mapcount==0).
3294                 *
3295                 * B)
3296                 * When the old page was mapped but migraion fails, the kernel
3297                 * remaps it. A charge for it is kept by MIGRATION flag even
3298                 * if mapcount goes down to 0. We can do remap successfully
3299                 * without charging it again.
3300                 *
3301                 * C)
3302                 * The "old" page is under lock_page() until the end of
3303                 * migration, so, the old page itself will not be swapped-out.
3304                 * If the new page is swapped out before end_migraton, our
3305                 * hook to usual swap-out path will catch the event.
3306                 */
3307                if (PageAnon(page))
3308                        SetPageCgroupMigration(pc);
3309        }
3310        unlock_page_cgroup(pc);
3311        /*
3312         * If the page is not charged at this point,
3313         * we return here.
3314         */
3315        if (!memcg)
3316                return;
3317
3318        *memcgp = memcg;
3319        /*
3320         * We charge new page before it's used/mapped. So, even if unlock_page()
3321         * is called before end_migration, we can catch all events on this new
3322         * page. In the case new page is migrated but not remapped, new page's
3323         * mapcount will be finally 0 and we call uncharge in end_migration().
3324         */
3325        if (PageAnon(page))
3326                ctype = MEM_CGROUP_CHARGE_TYPE_ANON;
3327        else
3328                ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
3329        /*
3330         * The page is committed to the memcg, but it's not actually
3331         * charged to the res_counter since we plan on replacing the
3332         * old one and only one page is going to be left afterwards.
3333         */
3334        __mem_cgroup_commit_charge(memcg, newpage, 1, ctype, false);
3335}
3336
3337/* remove redundant charge if migration failed*/
3338void mem_cgroup_end_migration(struct mem_cgroup *memcg,
3339        struct page *oldpage, struct page *newpage, bool migration_ok)
3340{
3341        struct page *used, *unused;
3342        struct page_cgroup *pc;
3343        bool anon;
3344
3345        if (!memcg)
3346                return;
3347        /* blocks rmdir() */
3348        cgroup_exclude_rmdir(&memcg->css);
3349        if (!migration_ok) {
3350                used = oldpage;
3351                unused = newpage;
3352        } else {
3353                used = newpage;
3354                unused = oldpage;
3355        }
3356        anon = PageAnon(used);
3357        __mem_cgroup_uncharge_common(unused,
3358                                     anon ? MEM_CGROUP_CHARGE_TYPE_ANON
3359                                     : MEM_CGROUP_CHARGE_TYPE_CACHE,
3360                                     true);
3361        css_put(&memcg->css);
3362        /*
3363         * We disallowed uncharge of pages under migration because mapcount
3364         * of the page goes down to zero, temporarly.
3365         * Clear the flag and check the page should be charged.
3366         */
3367        pc = lookup_page_cgroup(oldpage);
3368        lock_page_cgroup(pc);
3369        ClearPageCgroupMigration(pc);
3370        unlock_page_cgroup(pc);
3371
3372        /*
3373         * If a page is a file cache, radix-tree replacement is very atomic
3374         * and we can skip this check. When it was an Anon page, its mapcount
3375         * goes down to 0. But because we added MIGRATION flage, it's not
3376         * uncharged yet. There are several case but page->mapcount check
3377         * and USED bit check in mem_cgroup_uncharge_page() will do enough
3378         * check. (see prepare_charge() also)
3379         */
3380        if (anon)
3381                mem_cgroup_uncharge_page(used);
3382        /*
3383         * At migration, we may charge account against cgroup which has no
3384         * tasks.
3385         * So, rmdir()->pre_destroy() can be called while we do this charge.
3386         * In that case, we need to call pre_destroy() again. check it here.
3387         */
3388        cgroup_release_and_wakeup_rmdir(&memcg->css);
3389}
3390
3391/*
3392 * At replace page cache, newpage is not under any memcg but it's on
3393 * LRU. So, this function doesn't touch res_counter but handles LRU
3394 * in correct way. Both pages are locked so we cannot race with uncharge.
3395 */
3396void mem_cgroup_replace_page_cache(struct page *oldpage,
3397                                  struct page *newpage)
3398{
3399        struct mem_cgroup *memcg = NULL;
3400        struct page_cgroup *pc;
3401        enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
3402
3403        if (mem_cgroup_disabled())
3404                return;
3405
3406        pc = lookup_page_cgroup(oldpage);
3407        /* fix accounting on old pages */
3408        lock_page_cgroup(pc);
3409        if (PageCgroupUsed(pc)) {
3410                memcg = pc->mem_cgroup;
3411                mem_cgroup_charge_statistics(memcg, false, -1);
3412                ClearPageCgroupUsed(pc);
3413        }
3414        unlock_page_cgroup(pc);
3415
3416        /*
3417         * When called from shmem_replace_page(), in some cases the
3418         * oldpage has already been charged, and in some cases not.
3419         */
3420        if (!memcg)
3421                return;
3422        /*
3423         * Even if newpage->mapping was NULL before starting replacement,
3424         * the newpage may be on LRU(or pagevec for LRU) already. We lock
3425         * LRU while we overwrite pc->mem_cgroup.
3426         */
3427        __mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
3428}
3429
3430#ifdef CONFIG_DEBUG_VM
3431static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
3432{
3433        struct page_cgroup *pc;
3434
3435        pc = lookup_page_cgroup(page);
3436        /*
3437         * Can be NULL while feeding pages into the page allocator for
3438         * the first time, i.e. during boot or memory hotplug;
3439         * or when mem_cgroup_disabled().
3440         */
3441        if (likely(pc) && PageCgroupUsed(pc))
3442                return pc;
3443        return NULL;
3444}
3445
3446bool mem_cgroup_bad_page_check(struct page *page)
3447{
3448        if (mem_cgroup_disabled())
3449                return false;
3450
3451        return lookup_page_cgroup_used(page) != NULL;
3452}
3453
3454void mem_cgroup_print_bad_page(struct page *page)
3455{
3456        struct page_cgroup *pc;
3457
3458        pc = lookup_page_cgroup_used(page);
3459        if (pc) {
3460                printk(KERN_ALERT "pc:%p pc->flags:%lx pc->mem_cgroup:%p\n",
3461                       pc, pc->flags, pc->mem_cgroup);
3462        }
3463}
3464#endif
3465
3466static DEFINE_MUTEX(set_limit_mutex);
3467
3468static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
3469                                unsigned long long val)
3470{
3471        int retry_count;
3472        u64 memswlimit, memlimit;
3473        int ret = 0;
3474        int children = mem_cgroup_count_children(memcg);
3475        u64 curusage, oldusage;
3476        int enlarge;
3477
3478        /*
3479         * For keeping hierarchical_reclaim simple, how long we should retry
3480         * is depends on callers. We set our retry-count to be function
3481         * of # of children which we should visit in this loop.
3482         */
3483        retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
3484
3485        oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
3486
3487        enlarge = 0;
3488        while (retry_count) {
3489                if (signal_pending(current)) {
3490                        ret = -EINTR;
3491                        break;
3492                }
3493                /*
3494                 * Rather than hide all in some function, I do this in
3495                 * open coded manner. You see what this really does.
3496                 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
3497                 */
3498                mutex_lock(&set_limit_mutex);
3499                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3500                if (memswlimit < val) {
3501                        ret = -EINVAL;
3502                        mutex_unlock(&set_limit_mutex);
3503                        break;
3504                }
3505
3506                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3507                if (memlimit < val)
3508                        enlarge = 1;
3509
3510                ret = res_counter_set_limit(&memcg->res, val);
3511                if (!ret) {
3512                        if (memswlimit == val)
3513                                memcg->memsw_is_minimum = true;
3514                        else
3515                                memcg->memsw_is_minimum = false;
3516                }
3517                mutex_unlock(&set_limit_mutex);
3518
3519                if (!ret)
3520                        break;
3521
3522                mem_cgroup_reclaim(memcg, GFP_KERNEL,
3523                                   MEM_CGROUP_RECLAIM_SHRINK);
3524                curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
3525                /* Usage is reduced ? */
3526                if (curusage >= oldusage)
3527                        retry_count--;
3528                else
3529                        oldusage = curusage;
3530        }
3531        if (!ret && enlarge)
3532                memcg_oom_recover(memcg);
3533
3534        return ret;
3535}
3536
3537static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
3538                                        unsigned long long val)
3539{
3540        int retry_count;
3541        u64 memlimit, memswlimit, oldusage, curusage;
3542        int children = mem_cgroup_count_children(memcg);
3543        int ret = -EBUSY;
3544        int enlarge = 0;
3545
3546        /* see mem_cgroup_resize_res_limit */
3547        retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
3548        oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
3549        while (retry_count) {
3550                if (signal_pending(current)) {
3551                        ret = -EINTR;
3552                        break;
3553                }
3554                /*
3555                 * Rather than hide all in some function, I do this in
3556                 * open coded manner. You see what this really does.
3557                 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
3558                 */
3559                mutex_lock(&set_limit_mutex);
3560                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
3561                if (memlimit > val) {
3562                        ret = -EINVAL;
3563                        mutex_unlock(&set_limit_mutex);
3564                        break;
3565                }
3566                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
3567                if (memswlimit < val)
3568                        enlarge = 1;
3569                ret = res_counter_set_limit(&memcg->memsw, val);
3570                if (!ret) {
3571                        if (memlimit == val)
3572                                memcg->memsw_is_minimum = true;
3573                        else
3574                                memcg->memsw_is_minimum = false;
3575                }
3576                mutex_unlock(&set_limit_mutex);
3577
3578                if (!ret)
3579                        break;
3580
3581                mem_cgroup_reclaim(memcg, GFP_KERNEL,
3582                                   MEM_CGROUP_RECLAIM_NOSWAP |
3583                                   MEM_CGROUP_RECLAIM_SHRINK);
3584                curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
3585                /* Usage is reduced ? */
3586                if (curusage >= oldusage)
3587                        retry_count--;
3588                else
3589                        oldusage = curusage;
3590        }
3591        if (!ret && enlarge)
3592                memcg_oom_recover(memcg);
3593        return ret;
3594}
3595
3596unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
3597                                            gfp_t gfp_mask,
3598                                            unsigned long *total_scanned)
3599{
3600        unsigned long nr_reclaimed = 0;
3601        struct mem_cgroup_per_zone *mz, *next_mz = NULL;
3602        unsigned long reclaimed;
3603        int loop = 0;
3604        struct mem_cgroup_tree_per_zone *mctz;
3605        unsigned long long excess;
3606        unsigned long nr_scanned;
3607
3608        if (order > 0)
3609                return 0;
3610
3611        mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
3612        /*
3613         * This loop can run a while, specially if mem_cgroup's continuously
3614         * keep exceeding their soft limit and putting the system under
3615         * pressure
3616         */
3617        do {
3618                if (next_mz)
3619                        mz = next_mz;
3620                else
3621                        mz = mem_cgroup_largest_soft_limit_node(mctz);
3622                if (!mz)
3623                        break;
3624
3625                nr_scanned = 0;
3626                reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone,
3627                                                    gfp_mask, &nr_scanned);
3628                nr_reclaimed += reclaimed;
3629                *total_scanned += nr_scanned;
3630                spin_lock(&mctz->lock);
3631
3632                /*
3633                 * If we failed to reclaim anything from this memory cgroup
3634                 * it is time to move on to the next cgroup
3635                 */
3636                next_mz = NULL;
3637                if (!reclaimed) {
3638                        do {
3639                                /*
3640                                 * Loop until we find yet another one.
3641                                 *
3642                                 * By the time we get the soft_limit lock
3643                                 * again, someone might have aded the
3644                                 * group back on the RB tree. Iterate to
3645                                 * make sure we get a different mem.
3646                                 * mem_cgroup_largest_soft_limit_node returns
3647                                 * NULL if no other cgroup is present on
3648                                 * the tree
3649                                 */
3650                                next_mz =
3651                                __mem_cgroup_largest_soft_limit_node(mctz);
3652                                if (next_mz == mz)
3653                                        css_put(&next_mz->memcg->css);
3654                                else /* next_mz == NULL or other memcg */
3655                                        break;
3656                        } while (1);
3657                }
3658                __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
3659                excess = res_counter_soft_limit_excess(&mz->memcg->res);
3660                /*
3661                 * One school of thought says that we should not add
3662                 * back the node to the tree if reclaim returns 0.
3663                 * But our reclaim could return 0, simply because due
3664                 * to priority we are exposing a smaller subset of
3665                 * memory to reclaim from. Consider this as a longer
3666                 * term TODO.
3667                 */
3668                /* If excess == 0, no tree ops */
3669                __mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess);
3670                spin_unlock(&mctz->lock);
3671                css_put(&mz->memcg->css);
3672                loop++;
3673                /*
3674                 * Could not reclaim anything and there are no more
3675                 * mem cgroups to try or we seem to be looping without
3676                 * reclaiming anything.
3677                 */
3678                if (!nr_reclaimed &&
3679                        (next_mz == NULL ||
3680                        loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
3681                        break;
3682        } while (!nr_reclaimed);
3683        if (next_mz)
3684                css_put(&next_mz->memcg->css);
3685        return nr_reclaimed;
3686}
3687
3688/*
3689 * Traverse a specified page_cgroup list and try to drop them all.  This doesn't
3690 * reclaim the pages page themselves - it just removes the page_cgroups.
3691 * Returns true if some page_cgroups were not freed, indicating that the caller
3692 * must retry this operation.
3693 */
3694static bool mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
3695                                int node, int zid, enum lru_list lru)
3696{
3697        struct mem_cgroup_per_zone *mz;
3698        unsigned long flags, loop;
3699        struct list_head *list;
3700        struct page *busy;
3701        struct zone *zone;
3702
3703        zone = &NODE_DATA(node)->node_zones[zid];
3704        mz = mem_cgroup_zoneinfo(memcg, node, zid);
3705        list = &mz->lruvec.lists[lru];
3706
3707        loop = mz->lru_size[lru];
3708        /* give some margin against EBUSY etc...*/
3709        loop += 256;
3710        busy = NULL;
3711        while (loop--) {
3712                struct page_cgroup *pc;
3713                struct page *page;
3714
3715                spin_lock_irqsave(&zone->lru_lock, flags);
3716                if (list_empty(list)) {
3717                        spin_unlock_irqrestore(&zone->lru_lock, flags);
3718                        break;
3719                }
3720                page = list_entry(list->prev, struct page, lru);
3721                if (busy == page) {
3722                        list_move(&page->lru, list);
3723                        busy = NULL;
3724                        spin_unlock_irqrestore(&zone->lru_lock, flags);
3725                        continue;
3726                }
3727                spin_unlock_irqrestore(&zone->lru_lock, flags);
3728
3729                pc = lookup_page_cgroup(page);
3730
3731                if (mem_cgroup_move_parent(page, pc, memcg)) {
3732                        /* found lock contention or "pc" is obsolete. */
3733                        busy = page;
3734                        cond_resched();
3735                } else
3736                        busy = NULL;
3737        }
3738        return !list_empty(list);
3739}
3740
3741/*
3742 * make mem_cgroup's charge to be 0 if there is no task.
3743 * This enables deleting this mem_cgroup.
3744 */
3745static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)
3746{
3747        int ret;
3748        int node, zid, shrink;
3749        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
3750        struct cgroup *cgrp = memcg->css.cgroup;
3751
3752        css_get(&memcg->css);
3753
3754        shrink = 0;
3755        /* should free all ? */
3756        if (free_all)
3757                goto try_to_free;
3758move_account:
3759        do {
3760                ret = -EBUSY;
3761                if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
3762                        goto out;
3763                /* This is for making all *used* pages to be on LRU. */
3764                lru_add_drain_all();
3765                drain_all_stock_sync(memcg);
3766                ret = 0;
3767                mem_cgroup_start_move(memcg);
3768                for_each_node_state(node, N_HIGH_MEMORY) {
3769                        for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
3770                                enum lru_list lru;
3771                                for_each_lru(lru) {
3772                                        ret = mem_cgroup_force_empty_list(memcg,
3773                                                        node, zid, lru);
3774                                        if (ret)
3775                                                break;
3776                                }
3777                        }
3778                        if (ret)
3779                                break;
3780                }
3781                mem_cgroup_end_move(memcg);
3782                memcg_oom_recover(memcg);
3783                cond_resched();
3784        /* "ret" should also be checked to ensure all lists are empty. */
3785        } while (res_counter_read_u64(&memcg->res, RES_USAGE) > 0 || ret);
3786out:
3787        css_put(&memcg->css);
3788        return ret;
3789
3790try_to_free:
3791        /* returns EBUSY if there is a task or if we come here twice. */
3792        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
3793                ret = -EBUSY;
3794                goto out;
3795        }
3796        /* we call try-to-free pages for make this cgroup empty */
3797        lru_add_drain_all();
3798        /* try to free all pages in this cgroup */
3799        shrink = 1;
3800        while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
3801                int progress;
3802
3803                if (signal_pending(current)) {
3804                        ret = -EINTR;
3805                        goto out;
3806                }
3807                progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
3808                                                false);
3809                if (!progress) {
3810                        nr_retries--;
3811                        /* maybe some writeback is necessary */
3812                        congestion_wait(BLK_RW_ASYNC, HZ/10);
3813                }
3814
3815        }
3816        lru_add_drain();
3817        /* try move_account...there may be some *locked* pages. */
3818        goto move_account;
3819}
3820
3821static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
3822{
3823        return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
3824}
3825
3826
3827static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
3828{
3829        return mem_cgroup_from_cont(cont)->use_hierarchy;
3830}
3831
3832static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
3833                                        u64 val)
3834{
3835        int retval = 0;
3836        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3837        struct cgroup *parent = cont->parent;
3838        struct mem_cgroup *parent_memcg = NULL;
3839
3840        if (parent)
3841                parent_memcg = mem_cgroup_from_cont(parent);
3842
3843        cgroup_lock();
3844
3845        if (memcg->use_hierarchy == val)
3846                goto out;
3847
3848        /*
3849         * If parent's use_hierarchy is set, we can't make any modifications
3850         * in the child subtrees. If it is unset, then the change can
3851         * occur, provided the current cgroup has no children.
3852         *
3853         * For the root cgroup, parent_mem is NULL, we allow value to be
3854         * set if there are no children.
3855         */
3856        if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
3857                                (val == 1 || val == 0)) {
3858                if (list_empty(&cont->children))
3859                        memcg->use_hierarchy = val;
3860                else
3861                        retval = -EBUSY;
3862        } else
3863                retval = -EINVAL;
3864
3865out:
3866        cgroup_unlock();
3867
3868        return retval;
3869}
3870
3871
3872static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
3873                                               enum mem_cgroup_stat_index idx)
3874{
3875        struct mem_cgroup *iter;
3876        long val = 0;
3877
3878        /* Per-cpu values can be negative, use a signed accumulator */
3879        for_each_mem_cgroup_tree(iter, memcg)
3880                val += mem_cgroup_read_stat(iter, idx);
3881
3882        if (val < 0) /* race ? */
3883                val = 0;
3884        return val;
3885}
3886
3887static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
3888{
3889        u64 val;
3890
3891        if (!mem_cgroup_is_root(memcg)) {
3892                if (!swap)
3893                        return res_counter_read_u64(&memcg->res, RES_USAGE);
3894                else
3895                        return res_counter_read_u64(&memcg->memsw, RES_USAGE);
3896        }
3897
3898        val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
3899        val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
3900
3901        if (swap)
3902                val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
3903
3904        return val << PAGE_SHIFT;
3905}
3906
3907static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
3908                               struct file *file, char __user *buf,
3909                               size_t nbytes, loff_t *ppos)
3910{
3911        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3912        char str[64];
3913        u64 val;
3914        int type, name, len;
3915
3916        type = MEMFILE_TYPE(cft->private);
3917        name = MEMFILE_ATTR(cft->private);
3918
3919        if (!do_swap_account && type == _MEMSWAP)
3920                return -EOPNOTSUPP;
3921
3922        switch (type) {
3923        case _MEM:
3924                if (name == RES_USAGE)
3925                        val = mem_cgroup_usage(memcg, false);
3926                else
3927                        val = res_counter_read_u64(&memcg->res, name);
3928                break;
3929        case _MEMSWAP:
3930                if (name == RES_USAGE)
3931                        val = mem_cgroup_usage(memcg, true);
3932                else
3933                        val = res_counter_read_u64(&memcg->memsw, name);
3934                break;
3935        default:
3936                BUG();
3937        }
3938
3939        len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
3940        return simple_read_from_buffer(buf, nbytes, ppos, str, len);
3941}
3942/*
3943 * The user of this function is...
3944 * RES_LIMIT.
3945 */
3946static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
3947                            const char *buffer)
3948{
3949        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
3950        int type, name;
3951        unsigned long long val;
3952        int ret;
3953
3954        type = MEMFILE_TYPE(cft->private);
3955        name = MEMFILE_ATTR(cft->private);
3956
3957        if (!do_swap_account && type == _MEMSWAP)
3958                return -EOPNOTSUPP;
3959
3960        switch (name) {
3961        case RES_LIMIT:
3962                if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3963                        ret = -EINVAL;
3964                        break;
3965                }
3966                /* This function does all necessary parse...reuse it */
3967                ret = res_counter_memparse_write_strategy(buffer, &val);
3968                if (ret)
3969                        break;
3970                if (type == _MEM)
3971                        ret = mem_cgroup_resize_limit(memcg, val);
3972                else
3973                        ret = mem_cgroup_resize_memsw_limit(memcg, val);
3974                break;
3975        case RES_SOFT_LIMIT:
3976                ret = res_counter_memparse_write_strategy(buffer, &val);
3977                if (ret)
3978                        break;
3979                /*
3980                 * For memsw, soft limits are hard to implement in terms
3981                 * of semantics, for now, we support soft limits for
3982                 * control without swap
3983                 */
3984                if (type == _MEM)
3985                        ret = res_counter_set_soft_limit(&memcg->res, val);
3986                else
3987                        ret = -EINVAL;
3988                break;
3989        default:
3990                ret = -EINVAL; /* should be BUG() ? */
3991                break;
3992        }
3993        return ret;
3994}
3995
3996static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
3997                unsigned long long *mem_limit, unsigned long long *memsw_limit)
3998{
3999        struct cgroup *cgroup;
4000        unsigned long long min_limit, min_memsw_limit, tmp;
4001
4002        min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
4003        min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
4004        cgroup = memcg->css.cgroup;
4005        if (!memcg->use_hierarchy)
4006                goto out;
4007
4008        while (cgroup->parent) {
4009                cgroup = cgroup->parent;
4010                memcg = mem_cgroup_from_cont(cgroup);
4011                if (!memcg->use_hierarchy)
4012                        break;
4013                tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
4014                min_limit = min(min_limit, tmp);
4015                tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
4016                min_memsw_limit = min(min_memsw_limit, tmp);
4017        }
4018out:
4019        *mem_limit = min_limit;
4020        *memsw_limit = min_memsw_limit;
4021}
4022
4023static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
4024{
4025        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4026        int type, name;
4027
4028        type = MEMFILE_TYPE(event);
4029        name = MEMFILE_ATTR(event);
4030
4031        if (!do_swap_account && type == _MEMSWAP)
4032                return -EOPNOTSUPP;
4033
4034        switch (name) {
4035        case RES_MAX_USAGE:
4036                if (type == _MEM)
4037                        res_counter_reset_max(&memcg->res);
4038                else
4039                        res_counter_reset_max(&memcg->memsw);
4040                break;
4041        case RES_FAILCNT:
4042                if (type == _MEM)
4043                        res_counter_reset_failcnt(&memcg->res);
4044                else
4045                        res_counter_reset_failcnt(&memcg->memsw);
4046                break;
4047        }
4048
4049        return 0;
4050}
4051
4052static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
4053                                        struct cftype *cft)
4054{
4055        return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
4056}
4057
4058#ifdef CONFIG_MMU
4059static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
4060                                        struct cftype *cft, u64 val)
4061{
4062        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4063
4064        if (val >= (1 << NR_MOVE_TYPE))
4065                return -EINVAL;
4066        /*
4067         * We check this value several times in both in can_attach() and
4068         * attach(), so we need cgroup lock to prevent this value from being
4069         * inconsistent.
4070         */
4071        cgroup_lock();
4072        memcg->move_charge_at_immigrate = val;
4073        cgroup_unlock();
4074
4075        return 0;
4076}
4077#else
4078static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
4079                                        struct cftype *cft, u64 val)
4080{
4081        return -ENOSYS;
4082}
4083#endif
4084
4085#ifdef CONFIG_NUMA
4086static int memcg_numa_stat_show(struct cgroup *cont, struct cftype *cft,
4087                                      struct seq_file *m)
4088{
4089        int nid;
4090        unsigned long total_nr, file_nr, anon_nr, unevictable_nr;
4091        unsigned long node_nr;
4092        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4093
4094        total_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL);
4095        seq_printf(m, "total=%lu", total_nr);
4096        for_each_node_state(nid, N_HIGH_MEMORY) {
4097                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL);
4098                seq_printf(m, " N%d=%lu", nid, node_nr);
4099        }
4100        seq_putc(m, '\n');
4101
4102        file_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_FILE);
4103        seq_printf(m, "file=%lu", file_nr);
4104        for_each_node_state(nid, N_HIGH_MEMORY) {
4105                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
4106                                LRU_ALL_FILE);
4107                seq_printf(m, " N%d=%lu", nid, node_nr);
4108        }
4109        seq_putc(m, '\n');
4110
4111        anon_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_ANON);
4112        seq_printf(m, "anon=%lu", anon_nr);
4113        for_each_node_state(nid, N_HIGH_MEMORY) {
4114                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
4115                                LRU_ALL_ANON);
4116                seq_printf(m, " N%d=%lu", nid, node_nr);
4117        }
4118        seq_putc(m, '\n');
4119
4120        unevictable_nr = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_UNEVICTABLE));
4121        seq_printf(m, "unevictable=%lu", unevictable_nr);
4122        for_each_node_state(nid, N_HIGH_MEMORY) {
4123                node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
4124                                BIT(LRU_UNEVICTABLE));
4125                seq_printf(m, " N%d=%lu", nid, node_nr);
4126        }
4127        seq_putc(m, '\n');
4128        return 0;
4129}
4130#endif /* CONFIG_NUMA */
4131
4132static const char * const mem_cgroup_lru_names[] = {
4133        "inactive_anon",
4134        "active_anon",
4135        "inactive_file",
4136        "active_file",
4137        "unevictable",
4138};
4139
4140static inline void mem_cgroup_lru_names_not_uptodate(void)
4141{
4142        BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
4143}
4144
4145static int memcg_stat_show(struct cgroup *cont, struct cftype *cft,
4146                                 struct seq_file *m)
4147{
4148        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
4149        struct mem_cgroup *mi;
4150        unsigned int i;
4151
4152        for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
4153                if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
4154                        continue;
4155                seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i],
4156                           mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
4157        }
4158
4159        for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++)
4160                seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i],
4161                           mem_cgroup_read_events(memcg, i));
4162
4163        for (i = 0; i < NR_LRU_LISTS; i++)
4164                seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i],
4165                           mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);
4166
4167        /* Hierarchical information */
4168        {
4169                unsigned long long limit, memsw_limit;
4170                memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
4171                seq_printf(m, "hierarchical_memory_limit %llu\n", limit);
4172                if (do_swap_account)
4173                        seq_printf(m, "hierarchical_memsw_limit %llu\n",
4174                                   memsw_limit);
4175        }
4176
4177        for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
4178                long long val = 0;
4179
4180                if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
4181                        continue;
4182                for_each_mem_cgroup_tree(mi, memcg)
4183                        val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE;
4184                seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val);
4185        }
4186
4187        for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
4188                unsigned long long val = 0;
4189
4190                for_each_mem_cgroup_tree(mi, memcg)
4191                        val += mem_cgroup_read_events(mi, i);
4192                seq_printf(m, "total_%s %llu\n",
4193                           mem_cgroup_events_names[i], val);
4194        }
4195
4196        for (i = 0; i < NR_LRU_LISTS; i++) {
4197                unsigned long long val = 0;
4198
4199                for_each_mem_cgroup_tree(mi, memcg)
4200                        val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE;
4201                seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val);
4202        }
4203
4204#ifdef CONFIG_DEBUG_VM
4205        {
4206                int nid, zid;
4207                struct mem_cgroup_per_zone *mz;
4208                struct zone_reclaim_stat *rstat;
4209                unsigned long recent_rotated[2] = {0, 0};
4210                unsigned long recent_scanned[2] = {0, 0};
4211
4212                for_each_online_node(nid)
4213                        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
4214                                mz = mem_cgroup_zoneinfo(memcg, nid, zid);
4215                                rstat = &mz->lruvec.reclaim_stat;
4216
4217                                recent_rotated[0] += rstat->recent_rotated[0];
4218                                recent_rotated[1] += rstat->recent_rotated[1];
4219                                recent_scanned[0] += rstat->recent_scanned[0];
4220                                recent_scanned[1] += rstat->recent_scanned[1];
4221                        }
4222                seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]);
4223                seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]);
4224                seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]);
4225                seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]);
4226        }
4227#endif
4228
4229        return 0;
4230}
4231
4232static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
4233{
4234        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4235
4236        return mem_cgroup_swappiness(memcg);
4237}
4238
4239static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
4240                                       u64 val)
4241{
4242        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4243        struct mem_cgroup *parent;
4244
4245        if (val > 100)
4246                return -EINVAL;
4247
4248        if (cgrp->parent == NULL)
4249                return -EINVAL;
4250
4251        parent = mem_cgroup_from_cont(cgrp->parent);
4252
4253        cgroup_lock();
4254
4255        /* If under hierarchy, only empty-root can set this value */
4256        if ((parent->use_hierarchy) ||
4257            (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
4258                cgroup_unlock();
4259                return -EINVAL;
4260        }
4261
4262        memcg->swappiness = val;
4263
4264        cgroup_unlock();
4265
4266        return 0;
4267}
4268
4269static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
4270{
4271        struct mem_cgroup_threshold_ary *t;
4272        u64 usage;
4273        int i;
4274
4275        rcu_read_lock();
4276        if (!swap)
4277                t = rcu_dereference(memcg->thresholds.primary);
4278        else
4279                t = rcu_dereference(memcg->memsw_thresholds.primary);
4280
4281        if (!t)
4282                goto unlock;
4283
4284        usage = mem_cgroup_usage(memcg, swap);
4285
4286        /*
4287         * current_threshold points to threshold just below or equal to usage.
4288         * If it's not true, a threshold was crossed after last
4289         * call of __mem_cgroup_threshold().
4290         */
4291        i = t->current_threshold;
4292
4293        /*
4294         * Iterate backward over array of thresholds starting from
4295         * current_threshold and check if a threshold is crossed.
4296         * If none of thresholds below usage is crossed, we read
4297         * only one element of the array here.
4298         */
4299        for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
4300                eventfd_signal(t->entries[i].eventfd, 1);
4301
4302        /* i = current_threshold + 1 */
4303        i++;
4304
4305        /*
4306         * Iterate forward over array of thresholds starting from
4307         * current_threshold+1 and check if a threshold is crossed.
4308         * If none of thresholds above usage is crossed, we read
4309         * only one element of the array here.
4310         */
4311        for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
4312                eventfd_signal(t->entries[i].eventfd, 1);
4313
4314        /* Update current_threshold */
4315        t->current_threshold = i - 1;
4316unlock:
4317        rcu_read_unlock();
4318}
4319
4320static void mem_cgroup_threshold(struct mem_cgroup *memcg)
4321{
4322        while (memcg) {
4323                __mem_cgroup_threshold(memcg, false);
4324                if (do_swap_account)
4325                        __mem_cgroup_threshold(memcg, true);
4326
4327                memcg = parent_mem_cgroup(memcg);
4328        }
4329}
4330
4331static int compare_thresholds(const void *a, const void *b)
4332{
4333        const struct mem_cgroup_threshold *_a = a;
4334        const struct mem_cgroup_threshold *_b = b;
4335
4336        return _a->threshold - _b->threshold;
4337}
4338
4339static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
4340{
4341        struct mem_cgroup_eventfd_list *ev;
4342
4343        list_for_each_entry(ev, &memcg->oom_notify, list)
4344                eventfd_signal(ev->eventfd, 1);
4345        return 0;
4346}
4347
4348static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
4349{
4350        struct mem_cgroup *iter;
4351
4352        for_each_mem_cgroup_tree(iter, memcg)
4353                mem_cgroup_oom_notify_cb(iter);
4354}
4355
4356static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
4357        struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
4358{
4359        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4360        struct mem_cgroup_thresholds *thresholds;
4361        struct mem_cgroup_threshold_ary *new;
4362        int type = MEMFILE_TYPE(cft->private);
4363        u64 threshold, usage;
4364        int i, size, ret;
4365
4366        ret = res_counter_memparse_write_strategy(args, &threshold);
4367        if (ret)
4368                return ret;
4369
4370        mutex_lock(&memcg->thresholds_lock);
4371
4372        if (type == _MEM)
4373                thresholds = &memcg->thresholds;
4374        else if (type == _MEMSWAP)
4375                thresholds = &memcg->memsw_thresholds;
4376        else
4377                BUG();
4378
4379        usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
4380
4381        /* Check if a threshold crossed before adding a new one */
4382        if (thresholds->primary)
4383                __mem_cgroup_threshold(memcg, type == _MEMSWAP);
4384
4385        size = thresholds->primary ? thresholds->primary->size + 1 : 1;
4386
4387        /* Allocate memory for new array of thresholds */
4388        new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
4389                        GFP_KERNEL);
4390        if (!new) {
4391                ret = -ENOMEM;
4392                goto unlock;
4393        }
4394        new->size = size;
4395
4396        /* Copy thresholds (if any) to new array */
4397        if (thresholds->primary) {
4398                memcpy(new->entries, thresholds->primary->entries, (size - 1) *
4399                                sizeof(struct mem_cgroup_threshold));
4400        }
4401
4402        /* Add new threshold */
4403        new->entries[size - 1].eventfd = eventfd;
4404        new->entries[size - 1].threshold = threshold;
4405
4406        /* Sort thresholds. Registering of new threshold isn't time-critical */
4407        sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
4408                        compare_thresholds, NULL);
4409
4410        /* Find current threshold */
4411        new->current_threshold = -1;
4412        for (i = 0; i < size; i++) {
4413                if (new->entries[i].threshold <= usage) {
4414                        /*
4415                         * new->current_threshold will not be used until
4416                         * rcu_assign_pointer(), so it's safe to increment
4417                         * it here.
4418                         */
4419                        ++new->current_threshold;
4420                } else
4421                        break;
4422        }
4423
4424        /* Free old spare buffer and save old primary buffer as spare */
4425        kfree(thresholds->spare);
4426        thresholds->spare = thresholds->primary;
4427
4428        rcu_assign_pointer(thresholds->primary, new);
4429
4430        /* To be sure that nobody uses thresholds */
4431        synchronize_rcu();
4432
4433unlock:
4434        mutex_unlock(&memcg->thresholds_lock);
4435
4436        return ret;
4437}
4438
4439static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
4440        struct cftype *cft, struct eventfd_ctx *eventfd)
4441{
4442        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4443        struct mem_cgroup_thresholds *thresholds;
4444        struct mem_cgroup_threshold_ary *new;
4445        int type = MEMFILE_TYPE(cft->private);
4446        u64 usage;
4447        int i, j, size;
4448
4449        mutex_lock(&memcg->thresholds_lock);
4450        if (type == _MEM)
4451                thresholds = &memcg->thresholds;
4452        else if (type == _MEMSWAP)
4453                thresholds = &memcg->memsw_thresholds;
4454        else
4455                BUG();
4456
4457        if (!thresholds->primary)
4458                goto unlock;
4459
4460        usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
4461
4462        /* Check if a threshold crossed before removing */
4463        __mem_cgroup_threshold(memcg, type == _MEMSWAP);
4464
4465        /* Calculate new number of threshold */
4466        size = 0;
4467        for (i = 0; i < thresholds->primary->size; i++) {
4468                if (thresholds->primary->entries[i].eventfd != eventfd)
4469                        size++;
4470        }
4471
4472        new = thresholds->spare;
4473
4474        /* Set thresholds array to NULL if we don't have thresholds */
4475        if (!size) {
4476                kfree(new);
4477                new = NULL;
4478                goto swap_buffers;
4479        }
4480
4481        new->size = size;
4482
4483        /* Copy thresholds and find current threshold */
4484        new->current_threshold = -1;
4485        for (i = 0, j = 0; i < thresholds->primary->size; i++) {
4486                if (thresholds->primary->entries[i].eventfd == eventfd)
4487                        continue;
4488
4489                new->entries[j] = thresholds->primary->entries[i];
4490                if (new->entries[j].threshold <= usage) {
4491                        /*
4492                         * new->current_threshold will not be used
4493                         * until rcu_assign_pointer(), so it's safe to increment
4494                         * it here.
4495                         */
4496                        ++new->current_threshold;
4497                }
4498                j++;
4499        }
4500
4501swap_buffers:
4502        /* Swap primary and spare array */
4503        thresholds->spare = thresholds->primary;
4504        /* If all events are unregistered, free the spare array */
4505        if (!new) {
4506                kfree(thresholds->spare);
4507                thresholds->spare = NULL;
4508        }
4509
4510        rcu_assign_pointer(thresholds->primary, new);
4511
4512        /* To be sure that nobody uses thresholds */
4513        synchronize_rcu();
4514unlock:
4515        mutex_unlock(&memcg->thresholds_lock);
4516}
4517
4518static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
4519        struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
4520{
4521        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4522        struct mem_cgroup_eventfd_list *event;
4523        int type = MEMFILE_TYPE(cft->private);
4524
4525        BUG_ON(type != _OOM_TYPE);
4526        event = kmalloc(sizeof(*event), GFP_KERNEL);
4527        if (!event)
4528                return -ENOMEM;
4529
4530        spin_lock(&memcg_oom_lock);
4531
4532        event->eventfd = eventfd;
4533        list_add(&event->list, &memcg->oom_notify);
4534
4535        /* already in OOM ? */
4536        if (atomic_read(&memcg->under_oom))
4537                eventfd_signal(eventfd, 1);
4538        spin_unlock(&memcg_oom_lock);
4539
4540        return 0;
4541}
4542
4543static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
4544        struct cftype *cft, struct eventfd_ctx *eventfd)
4545{
4546        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4547        struct mem_cgroup_eventfd_list *ev, *tmp;
4548        int type = MEMFILE_TYPE(cft->private);
4549
4550        BUG_ON(type != _OOM_TYPE);
4551
4552        spin_lock(&memcg_oom_lock);
4553
4554        list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
4555                if (ev->eventfd == eventfd) {
4556                        list_del(&ev->list);
4557                        kfree(ev);
4558                }
4559        }
4560
4561        spin_unlock(&memcg_oom_lock);
4562}
4563
4564static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
4565        struct cftype *cft,  struct cgroup_map_cb *cb)
4566{
4567        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4568
4569        cb->fill(cb, "oom_kill_disable", memcg->oom_kill_disable);
4570
4571        if (atomic_read(&memcg->under_oom))
4572                cb->fill(cb, "under_oom", 1);
4573        else
4574                cb->fill(cb, "under_oom", 0);
4575        return 0;
4576}
4577
4578static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
4579        struct cftype *cft, u64 val)
4580{
4581        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
4582        struct mem_cgroup *parent;
4583
4584        /* cannot set to root cgroup and only 0 and 1 are allowed */
4585        if (!cgrp->parent || !((val == 0) || (val == 1)))
4586                return -EINVAL;
4587
4588        parent = mem_cgroup_from_cont(cgrp->parent);
4589
4590        cgroup_lock();
4591        /* oom-kill-disable is a flag for subhierarchy. */
4592        if ((parent->use_hierarchy) ||
4593            (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
4594                cgroup_unlock();
4595                return -EINVAL;
4596        }
4597        memcg->oom_kill_disable = val;
4598        if (!val)
4599                memcg_oom_recover(memcg);
4600        cgroup_unlock();
4601        return 0;
4602}
4603
4604#ifdef CONFIG_MEMCG_KMEM
4605static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
4606{
4607        return mem_cgroup_sockets_init(memcg, ss);
4608};
4609
4610static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
4611{
4612        mem_cgroup_sockets_destroy(memcg);
4613}
4614#else
4615static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
4616{
4617        return 0;
4618}
4619
4620static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
4621{
4622}
4623#endif
4624
4625static struct cftype mem_cgroup_files[] = {
4626        {
4627                .name = "usage_in_bytes",
4628                .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
4629                .read = mem_cgroup_read,
4630                .register_event = mem_cgroup_usage_register_event,
4631                .unregister_event = mem_cgroup_usage_unregister_event,
4632        },
4633        {
4634                .name = "max_usage_in_bytes",
4635                .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
4636                .trigger = mem_cgroup_reset,
4637                .read = mem_cgroup_read,
4638        },
4639        {
4640                .name = "limit_in_bytes",
4641                .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
4642                .write_string = mem_cgroup_write,
4643                .read = mem_cgroup_read,
4644        },
4645        {
4646                .name = "soft_limit_in_bytes",
4647                .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
4648                .write_string = mem_cgroup_write,
4649                .read = mem_cgroup_read,
4650        },
4651        {
4652                .name = "failcnt",
4653                .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
4654                .trigger = mem_cgroup_reset,
4655                .read = mem_cgroup_read,
4656        },
4657        {
4658                .name = "stat",
4659                .read_seq_string = memcg_stat_show,
4660        },
4661        {
4662                .name = "force_empty",
4663                .trigger = mem_cgroup_force_empty_write,
4664        },
4665        {
4666                .name = "use_hierarchy",
4667                .write_u64 = mem_cgroup_hierarchy_write,
4668                .read_u64 = mem_cgroup_hierarchy_read,
4669        },
4670        {
4671                .name = "swappiness",
4672                .read_u64 = mem_cgroup_swappiness_read,
4673                .write_u64 = mem_cgroup_swappiness_write,
4674        },
4675        {
4676                .name = "move_charge_at_immigrate",
4677                .read_u64 = mem_cgroup_move_charge_read,
4678                .write_u64 = mem_cgroup_move_charge_write,
4679        },
4680        {
4681                .name = "oom_control",
4682                .read_map = mem_cgroup_oom_control_read,
4683                .write_u64 = mem_cgroup_oom_control_write,
4684                .register_event = mem_cgroup_oom_register_event,
4685                .unregister_event = mem_cgroup_oom_unregister_event,
4686                .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
4687        },
4688#ifdef CONFIG_NUMA
4689        {
4690                .name = "numa_stat",
4691                .read_seq_string = memcg_numa_stat_show,
4692        },
4693#endif
4694#ifdef CONFIG_MEMCG_SWAP
4695        {
4696                .name = "memsw.usage_in_bytes",
4697                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
4698                .read = mem_cgroup_read,
4699                .register_event = mem_cgroup_usage_register_event,
4700                .unregister_event = mem_cgroup_usage_unregister_event,
4701        },
4702        {
4703                .name = "memsw.max_usage_in_bytes",
4704                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
4705                .trigger = mem_cgroup_reset,
4706                .read = mem_cgroup_read,
4707        },
4708        {
4709                .name = "memsw.limit_in_bytes",
4710                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
4711                .write_string = mem_cgroup_write,
4712                .read = mem_cgroup_read,
4713        },
4714        {
4715                .name = "memsw.failcnt",
4716                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
4717                .trigger = mem_cgroup_reset,
4718                .read = mem_cgroup_read,
4719        },
4720#endif
4721        { },    /* terminate */
4722};
4723
4724static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
4725{
4726        struct mem_cgroup_per_node *pn;
4727        struct mem_cgroup_per_zone *mz;
4728        int zone, tmp = node;
4729        /*
4730         * This routine is called against possible nodes.
4731         * But it's BUG to call kmalloc() against offline node.
4732         *
4733         * TODO: this routine can waste much memory for nodes which will
4734         *       never be onlined. It's better to use memory hotplug callback
4735         *       function.
4736         */
4737        if (!node_state(node, N_NORMAL_MEMORY))
4738                tmp = -1;
4739        pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
4740        if (!pn)
4741                return 1;
4742
4743        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4744                mz = &pn->zoneinfo[zone];
4745                lruvec_init(&mz->lruvec, &NODE_DATA(node)->node_zones[zone]);
4746                mz->usage_in_excess = 0;
4747                mz->on_tree = false;
4748                mz->memcg = memcg;
4749        }
4750        memcg->info.nodeinfo[node] = pn;
4751        return 0;
4752}
4753
4754static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
4755{
4756        kfree(memcg->info.nodeinfo[node]);
4757}
4758
4759static struct mem_cgroup *mem_cgroup_alloc(void)
4760{
4761        struct mem_cgroup *memcg;
4762        int size = sizeof(struct mem_cgroup);
4763
4764        /* Can be very big if MAX_NUMNODES is very big */
4765        if (size < PAGE_SIZE)
4766                memcg = kzalloc(size, GFP_KERNEL);
4767        else
4768                memcg = vzalloc(size);
4769
4770        if (!memcg)
4771                return NULL;
4772
4773        memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
4774        if (!memcg->stat)
4775                goto out_free;
4776        spin_lock_init(&memcg->pcp_counter_lock);
4777        return memcg;
4778
4779out_free:
4780        if (size < PAGE_SIZE)
4781                kfree(memcg);
4782        else
4783                vfree(memcg);
4784        return NULL;
4785}
4786
4787/*
4788 * Helpers for freeing a kmalloc()ed/vzalloc()ed mem_cgroup by RCU,
4789 * but in process context.  The work_freeing structure is overlaid
4790 * on the rcu_freeing structure, which itself is overlaid on memsw.
4791 */
4792static void free_work(struct work_struct *work)
4793{
4794        struct mem_cgroup *memcg;
4795        int size = sizeof(struct mem_cgroup);
4796
4797        memcg = container_of(work, struct mem_cgroup, work_freeing);
4798        /*
4799         * We need to make sure that (at least for now), the jump label
4800         * destruction code runs outside of the cgroup lock. This is because
4801         * get_online_cpus(), which is called from the static_branch update,
4802         * can't be called inside the cgroup_lock. cpusets are the ones
4803         * enforcing this dependency, so if they ever change, we might as well.
4804         *
4805         * schedule_work() will guarantee this happens. Be careful if you need
4806         * to move this code around, and make sure it is outside
4807         * the cgroup_lock.
4808         */
4809        disarm_sock_keys(memcg);
4810        if (size < PAGE_SIZE)
4811                kfree(memcg);
4812        else
4813                vfree(memcg);
4814}
4815
4816static void free_rcu(struct rcu_head *rcu_head)
4817{
4818        struct mem_cgroup *memcg;
4819
4820        memcg = container_of(rcu_head, struct mem_cgroup, rcu_freeing);
4821        INIT_WORK(&memcg->work_freeing, free_work);
4822        schedule_work(&memcg->work_freeing);
4823}
4824
4825/*
4826 * At destroying mem_cgroup, references from swap_cgroup can remain.
4827 * (scanning all at force_empty is too costly...)
4828 *
4829 * Instead of clearing all references at force_empty, we remember
4830 * the number of reference from swap_cgroup and free mem_cgroup when
4831 * it goes down to 0.
4832 *
4833 * Removal of cgroup itself succeeds regardless of refs from swap.
4834 */
4835
4836static void __mem_cgroup_free(struct mem_cgroup *memcg)
4837{
4838        int node;
4839
4840        mem_cgroup_remove_from_trees(memcg);
4841        free_css_id(&mem_cgroup_subsys, &memcg->css);
4842
4843        for_each_node(node)
4844                free_mem_cgroup_per_zone_info(memcg, node);
4845
4846        free_percpu(memcg->stat);
4847        call_rcu(&memcg->rcu_freeing, free_rcu);
4848}
4849
4850static void mem_cgroup_get(struct mem_cgroup *memcg)
4851{
4852        atomic_inc(&memcg->refcnt);
4853}
4854
4855static void __mem_cgroup_put(struct mem_cgroup *memcg, int count)
4856{
4857        if (atomic_sub_and_test(count, &memcg->refcnt)) {
4858                struct mem_cgroup *parent = parent_mem_cgroup(memcg);
4859                __mem_cgroup_free(memcg);
4860                if (parent)
4861                        mem_cgroup_put(parent);
4862        }
4863}
4864
4865static void mem_cgroup_put(struct mem_cgroup *memcg)
4866{
4867        __mem_cgroup_put(memcg, 1);
4868}
4869
4870/*
4871 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
4872 */
4873struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
4874{
4875        if (!memcg->res.parent)
4876                return NULL;
4877        return mem_cgroup_from_res_counter(memcg->res.parent, res);
4878}
4879EXPORT_SYMBOL(parent_mem_cgroup);
4880
4881#ifdef CONFIG_MEMCG_SWAP
4882static void __init enable_swap_cgroup(void)
4883{
4884        if (!mem_cgroup_disabled() && really_do_swap_account)
4885                do_swap_account = 1;
4886}
4887#else
4888static void __init enable_swap_cgroup(void)
4889{
4890}
4891#endif
4892
4893static int mem_cgroup_soft_limit_tree_init(void)
4894{
4895        struct mem_cgroup_tree_per_node *rtpn;
4896        struct mem_cgroup_tree_per_zone *rtpz;
4897        int tmp, node, zone;
4898
4899        for_each_node(node) {
4900                tmp = node;
4901                if (!node_state(node, N_NORMAL_MEMORY))
4902                        tmp = -1;
4903                rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
4904                if (!rtpn)
4905                        goto err_cleanup;
4906
4907                soft_limit_tree.rb_tree_per_node[node] = rtpn;
4908
4909                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
4910                        rtpz = &rtpn->rb_tree_per_zone[zone];
4911                        rtpz->rb_root = RB_ROOT;
4912                        spin_lock_init(&rtpz->lock);
4913                }
4914        }
4915        return 0;
4916
4917err_cleanup:
4918        for_each_node(node) {
4919                if (!soft_limit_tree.rb_tree_per_node[node])
4920                        break;
4921                kfree(soft_limit_tree.rb_tree_per_node[node]);
4922                soft_limit_tree.rb_tree_per_node[node] = NULL;
4923        }
4924        return 1;
4925
4926}
4927
4928static struct cgroup_subsys_state * __ref
4929mem_cgroup_create(struct cgroup *cont)
4930{
4931        struct mem_cgroup *memcg, *parent;
4932        long error = -ENOMEM;
4933        int node;
4934
4935        memcg = mem_cgroup_alloc();
4936        if (!memcg)
4937                return ERR_PTR(error);
4938
4939        for_each_node(node)
4940                if (alloc_mem_cgroup_per_zone_info(memcg, node))
4941                        goto free_out;
4942
4943        /* root ? */
4944        if (cont->parent == NULL) {
4945                int cpu;
4946                enable_swap_cgroup();
4947                parent = NULL;
4948                if (mem_cgroup_soft_limit_tree_init())
4949                        goto free_out;
4950                root_mem_cgroup = memcg;
4951                for_each_possible_cpu(cpu) {
4952                        struct memcg_stock_pcp *stock =
4953                                                &per_cpu(memcg_stock, cpu);
4954                        INIT_WORK(&stock->work, drain_local_stock);
4955                }
4956                hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
4957        } else {
4958                parent = mem_cgroup_from_cont(cont->parent);
4959                memcg->use_hierarchy = parent->use_hierarchy;
4960                memcg->oom_kill_disable = parent->oom_kill_disable;
4961        }
4962
4963        if (parent && parent->use_hierarchy) {
4964                res_counter_init(&memcg->res, &parent->res);
4965                res_counter_init(&memcg->memsw, &parent->memsw);
4966                /*
4967                 * We increment refcnt of the parent to ensure that we can
4968                 * safely access it on res_counter_charge/uncharge.
4969                 * This refcnt will be decremented when freeing this
4970                 * mem_cgroup(see mem_cgroup_put).
4971                 */
4972                mem_cgroup_get(parent);
4973        } else {
4974                res_counter_init(&memcg->res, NULL);
4975                res_counter_init(&memcg->memsw, NULL);
4976        }
4977        memcg->last_scanned_node = MAX_NUMNODES;
4978        INIT_LIST_HEAD(&memcg->oom_notify);
4979
4980        if (parent)
4981                memcg->swappiness = mem_cgroup_swappiness(parent);
4982        atomic_set(&memcg->refcnt, 1);
4983        memcg->move_charge_at_immigrate = 0;
4984        mutex_init(&memcg->thresholds_lock);
4985        spin_lock_init(&memcg->move_lock);
4986
4987        error = memcg_init_kmem(memcg, &mem_cgroup_subsys);
4988        if (error) {
4989                /*
4990                 * We call put now because our (and parent's) refcnts
4991                 * are already in place. mem_cgroup_put() will internally
4992                 * call __mem_cgroup_free, so return directly
4993                 */
4994                mem_cgroup_put(memcg);
4995                return ERR_PTR(error);
4996        }
4997        return &memcg->css;
4998free_out:
4999        __mem_cgroup_free(memcg);
5000        return ERR_PTR(error);
5001}
5002
5003static int mem_cgroup_pre_destroy(struct cgroup *cont)
5004{
5005        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
5006
5007        return mem_cgroup_force_empty(memcg, false);
5008}
5009
5010static void mem_cgroup_destroy(struct cgroup *cont)
5011{
5012        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
5013
5014        kmem_cgroup_destroy(memcg);
5015
5016        mem_cgroup_put(memcg);
5017}
5018
5019#ifdef CONFIG_MMU
5020/* Handlers for move charge at task migration. */
5021#define PRECHARGE_COUNT_AT_ONCE 256
5022static int mem_cgroup_do_precharge(unsigned long count)
5023{
5024        int ret = 0;
5025        int batch_count = PRECHARGE_COUNT_AT_ONCE;
5026        struct mem_cgroup *memcg = mc.to;
5027
5028        if (mem_cgroup_is_root(memcg)) {
5029                mc.precharge += count;
5030                /* we don't need css_get for root */
5031                return ret;
5032        }
5033        /* try to charge at once */
5034        if (count > 1) {
5035                struct res_counter *dummy;
5036                /*
5037                 * "memcg" cannot be under rmdir() because we've already checked
5038                 * by cgroup_lock_live_cgroup() that it is not removed and we
5039                 * are still under the same cgroup_mutex. So we can postpone
5040                 * css_get().
5041                 */
5042                if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy))
5043                        goto one_by_one;
5044                if (do_swap_account && res_counter_charge(&memcg->memsw,
5045                                                PAGE_SIZE * count, &dummy)) {
5046                        res_counter_uncharge(&memcg->res, PAGE_SIZE * count);
5047                        goto one_by_one;
5048                }
5049                mc.precharge += count;
5050                return ret;
5051        }
5052one_by_one:
5053        /* fall back to one by one charge */
5054        while (count--) {
5055                if (signal_pending(current)) {
5056                        ret = -EINTR;
5057                        break;
5058                }
5059                if (!batch_count--) {
5060                        batch_count = PRECHARGE_COUNT_AT_ONCE;
5061                        cond_resched();
5062                }
5063                ret = __mem_cgroup_try_charge(NULL,
5064                                        GFP_KERNEL, 1, &memcg, false);
5065                if (ret)
5066                        /* mem_cgroup_clear_mc() will do uncharge later */
5067                        return ret;
5068                mc.precharge++;
5069        }
5070        return ret;
5071}
5072
5073/**
5074 * get_mctgt_type - get target type of moving charge
5075 * @vma: the vma the pte to be checked belongs
5076 * @addr: the address corresponding to the pte to be checked
5077 * @ptent: the pte to be checked
5078 * @target: the pointer the target page or swap ent will be stored(can be NULL)
5079 *
5080 * Returns
5081 *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
5082 *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
5083 *     move charge. if @target is not NULL, the page is stored in target->page
5084 *     with extra refcnt got(Callers should handle it).
5085 *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
5086 *     target for charge migration. if @target is not NULL, the entry is stored
5087 *     in target->ent.
5088 *
5089 * Called with pte lock held.
5090 */
5091union mc_target {
5092        struct page     *page;
5093        swp_entry_t     ent;
5094};
5095
5096enum mc_target_type {
5097        MC_TARGET_NONE = 0,
5098        MC_TARGET_PAGE,
5099        MC_TARGET_SWAP,
5100};
5101
5102static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
5103                                                unsigned long addr, pte_t ptent)
5104{
5105        struct page *page = vm_normal_page(vma, addr, ptent);
5106
5107        if (!page || !page_mapped(page))
5108                return NULL;
5109        if (PageAnon(page)) {
5110                /* we don't move shared anon */
5111                if (!move_anon())
5112                        return NULL;
5113        } else if (!move_file())
5114                /* we ignore mapcount for file pages */
5115                return NULL;
5116        if (!get_page_unless_zero(page))
5117                return NULL;
5118
5119        return page;
5120}
5121
5122#ifdef CONFIG_SWAP
5123static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
5124                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
5125{
5126        struct page *page = NULL;
5127        swp_entry_t ent = pte_to_swp_entry(ptent);
5128
5129        if (!move_anon() || non_swap_entry(ent))
5130                return NULL;
5131        /*
5132         * Because lookup_swap_cache() updates some statistics counter,
5133         * we call find_get_page() with swapper_space directly.
5134         */
5135        page = find_get_page(&swapper_space, ent.val);
5136        if (do_swap_account)
5137                entry->val = ent.val;
5138
5139        return page;
5140}
5141#else
5142static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
5143                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
5144{
5145        return NULL;
5146}
5147#endif
5148
5149static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
5150                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
5151{
5152        struct page *page = NULL;
5153        struct address_space *mapping;
5154        pgoff_t pgoff;
5155
5156        if (!vma->vm_file) /* anonymous vma */
5157                return NULL;
5158        if (!move_file())
5159                return NULL;
5160
5161        mapping = vma->vm_file->f_mapping;
5162        if (pte_none(ptent))
5163                pgoff = linear_page_index(vma, addr);
5164        else /* pte_file(ptent) is true */
5165                pgoff = pte_to_pgoff(ptent);
5166
5167        /* page is moved even if it's not RSS of this task(page-faulted). */
5168        page = find_get_page(mapping, pgoff);
5169
5170#ifdef CONFIG_SWAP
5171        /* shmem/tmpfs may report page out on swap: account for that too. */
5172        if (radix_tree_exceptional_entry(page)) {
5173                swp_entry_t swap = radix_to_swp_entry(page);
5174                if (do_swap_account)
5175                        *entry = swap;
5176                page = find_get_page(&swapper_space, swap.val);
5177        }
5178#endif
5179        return page;
5180}
5181
5182static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
5183                unsigned long addr, pte_t ptent, union mc_target *target)
5184{
5185        struct page *page = NULL;
5186        struct page_cgroup *pc;
5187        enum mc_target_type ret = MC_TARGET_NONE;
5188        swp_entry_t ent = { .val = 0 };
5189
5190        if (pte_present(ptent))
5191                page = mc_handle_present_pte(vma, addr, ptent);
5192        else if (is_swap_pte(ptent))
5193                page = mc_handle_swap_pte(vma, addr, ptent, &ent);
5194        else if (pte_none(ptent) || pte_file(ptent))
5195                page = mc_handle_file_pte(vma, addr, ptent, &ent);
5196
5197        if (!page && !ent.val)
5198                return ret;
5199        if (page) {
5200                pc = lookup_page_cgroup(page);
5201                /*
5202                 * Do only loose check w/o page_cgroup lock.
5203                 * mem_cgroup_move_account() checks the pc is valid or not under
5204                 * the lock.
5205                 */
5206                if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
5207                        ret = MC_TARGET_PAGE;
5208                        if (target)
5209                                target->page = page;
5210                }
5211                if (!ret || !target)
5212                        put_page(page);
5213        }
5214        /* There is a swap entry and a page doesn't exist or isn't charged */
5215        if (ent.val && !ret &&
5216                        css_id(&mc.from->css) == lookup_swap_cgroup_id(ent)) {
5217                ret = MC_TARGET_SWAP;
5218                if (target)
5219                        target->ent = ent;
5220        }
5221        return ret;
5222}
5223
5224#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5225/*
5226 * We don't consider swapping or file mapped pages because THP does not
5227 * support them for now.
5228 * Caller should make sure that pmd_trans_huge(pmd) is true.
5229 */
5230static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
5231                unsigned long addr, pmd_t pmd, union mc_target *target)
5232{
5233        struct page *page = NULL;
5234        struct page_cgroup *pc;
5235        enum mc_target_type ret = MC_TARGET_NONE;
5236
5237        page = pmd_page(pmd);
5238        VM_BUG_ON(!page || !PageHead(page));
5239        if (!move_anon())
5240                return ret;
5241        pc = lookup_page_cgroup(page);
5242        if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
5243                ret = MC_TARGET_PAGE;
5244                if (target) {
5245                        get_page(page);
5246                        target->page = page;
5247                }
5248        }
5249        return ret;
5250}
5251#else
5252static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
5253                unsigned long addr, pmd_t pmd, union mc_target *target)
5254{
5255        return MC_TARGET_NONE;
5256}
5257#endif
5258
5259static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
5260                                        unsigned long addr, unsigned long end,
5261                                        struct mm_walk *walk)
5262{
5263        struct vm_area_struct *vma = walk->private;
5264        pte_t *pte;
5265        spinlock_t *ptl;
5266
5267        if (pmd_trans_huge_lock(pmd, vma) == 1) {
5268                if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
5269                        mc.precharge += HPAGE_PMD_NR;
5270                spin_unlock(&vma->vm_mm->page_table_lock);
5271                return 0;
5272        }
5273
5274        if (pmd_trans_unstable(pmd))
5275                return 0;
5276        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
5277        for (; addr != end; pte++, addr += PAGE_SIZE)
5278                if (get_mctgt_type(vma, addr, *pte, NULL))
5279                        mc.precharge++; /* increment precharge temporarily */
5280        pte_unmap_unlock(pte - 1, ptl);
5281        cond_resched();
5282
5283        return 0;
5284}
5285
5286static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
5287{
5288        unsigned long precharge;
5289        struct vm_area_struct *vma;
5290
5291        down_read(&mm->mmap_sem);
5292        for (vma = mm->mmap; vma; vma = vma->vm_next) {
5293                struct mm_walk mem_cgroup_count_precharge_walk = {
5294                        .pmd_entry = mem_cgroup_count_precharge_pte_range,
5295                        .mm = mm,
5296                        .private = vma,
5297                };
5298                if (is_vm_hugetlb_page(vma))
5299                        continue;
5300                walk_page_range(vma->vm_start, vma->vm_end,
5301                                        &mem_cgroup_count_precharge_walk);
5302        }
5303        up_read(&mm->mmap_sem);
5304
5305        precharge = mc.precharge;
5306        mc.precharge = 0;
5307
5308        return precharge;
5309}
5310
5311static int mem_cgroup_precharge_mc(struct mm_struct *mm)
5312{
5313        unsigned long precharge = mem_cgroup_count_precharge(mm);
5314
5315        VM_BUG_ON(mc.moving_task);
5316        mc.moving_task = current;
5317        return mem_cgroup_do_precharge(precharge);
5318}
5319
5320/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
5321static void __mem_cgroup_clear_mc(void)
5322{
5323        struct mem_cgroup *from = mc.from;
5324        struct mem_cgroup *to = mc.to;
5325
5326        /* we must uncharge all the leftover precharges from mc.to */
5327        if (mc.precharge) {
5328                __mem_cgroup_cancel_charge(mc.to, mc.precharge);
5329                mc.precharge = 0;
5330        }
5331        /*
5332         * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
5333         * we must uncharge here.
5334         */
5335        if (mc.moved_charge) {
5336                __mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
5337                mc.moved_charge = 0;
5338        }
5339        /* we must fixup refcnts and charges */
5340        if (mc.moved_swap) {
5341                /* uncharge swap account from the old cgroup */
5342                if (!mem_cgroup_is_root(mc.from))
5343                        res_counter_uncharge(&mc.from->memsw,
5344                                                PAGE_SIZE * mc.moved_swap);
5345                __mem_cgroup_put(mc.from, mc.moved_swap);
5346
5347                if (!mem_cgroup_is_root(mc.to)) {
5348                        /*
5349                         * we charged both to->res and to->memsw, so we should
5350                         * uncharge to->res.
5351                         */
5352                        res_counter_uncharge(&mc.to->res,
5353                                                PAGE_SIZE * mc.moved_swap);
5354                }
5355                /* we've already done mem_cgroup_get(mc.to) */
5356                mc.moved_swap = 0;
5357        }
5358        memcg_oom_recover(from);
5359        memcg_oom_recover(to);
5360        wake_up_all(&mc.waitq);
5361}
5362
5363static void mem_cgroup_clear_mc(void)
5364{
5365        struct mem_cgroup *from = mc.from;
5366
5367        /*
5368         * we must clear moving_task before waking up waiters at the end of
5369         * task migration.
5370         */
5371        mc.moving_task = NULL;
5372        __mem_cgroup_clear_mc();
5373        spin_lock(&mc.lock);
5374        mc.from = NULL;
5375        mc.to = NULL;
5376        spin_unlock(&mc.lock);
5377        mem_cgroup_end_move(from);
5378}
5379
5380static int mem_cgroup_can_attach(struct cgroup *cgroup,
5381                                 struct cgroup_taskset *tset)
5382{
5383        struct task_struct *p = cgroup_taskset_first(tset);
5384        int ret = 0;
5385        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
5386
5387        if (memcg->move_charge_at_immigrate) {
5388                struct mm_struct *mm;
5389                struct mem_cgroup *from = mem_cgroup_from_task(p);
5390
5391                VM_BUG_ON(from == memcg);
5392
5393                mm = get_task_mm(p);
5394                if (!mm)
5395                        return 0;
5396                /* We move charges only when we move a owner of the mm */
5397                if (mm->owner == p) {
5398                        VM_BUG_ON(mc.from);
5399                        VM_BUG_ON(mc.to);
5400                        VM_BUG_ON(mc.precharge);
5401                        VM_BUG_ON(mc.moved_charge);
5402                        VM_BUG_ON(mc.moved_swap);
5403                        mem_cgroup_start_move(from);
5404                        spin_lock(&mc.lock);
5405                        mc.from = from;
5406                        mc.to = memcg;
5407                        spin_unlock(&mc.lock);
5408                        /* We set mc.moving_task later */
5409
5410                        ret = mem_cgroup_precharge_mc(mm);
5411                        if (ret)
5412                                mem_cgroup_clear_mc();
5413                }
5414                mmput(mm);
5415        }
5416        return ret;
5417}
5418
5419static void mem_cgroup_cancel_attach(struct cgroup *cgroup,
5420                                     struct cgroup_taskset *tset)
5421{
5422        mem_cgroup_clear_mc();
5423}
5424
5425static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
5426                                unsigned long addr, unsigned long end,
5427                                struct mm_walk *walk)
5428{
5429        int ret = 0;
5430        struct vm_area_struct *vma = walk->private;
5431        pte_t *pte;
5432        spinlock_t *ptl;
5433        enum mc_target_type target_type;
5434        union mc_target target;
5435        struct page *page;
5436        struct page_cgroup *pc;
5437
5438        /*
5439         * We don't take compound_lock() here but no race with splitting thp
5440         * happens because:
5441         *  - if pmd_trans_huge_lock() returns 1, the relevant thp is not
5442         *    under splitting, which means there's no concurrent thp split,
5443         *  - if another thread runs into split_huge_page() just after we
5444         *    entered this if-block, the thread must wait for page table lock
5445         *    to be unlocked in __split_huge_page_splitting(), where the main
5446         *    part of thp split is not executed yet.
5447         */
5448        if (pmd_trans_huge_lock(pmd, vma) == 1) {
5449                if (mc.precharge < HPAGE_PMD_NR) {
5450                        spin_unlock(&vma->vm_mm->page_table_lock);
5451                        return 0;
5452                }
5453                target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
5454                if (target_type == MC_TARGET_PAGE) {
5455                        page = target.page;
5456                        if (!isolate_lru_page(page)) {
5457                                pc = lookup_page_cgroup(page);
5458                                if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
5459                                                        pc, mc.from, mc.to)) {
5460                                        mc.precharge -= HPAGE_PMD_NR;
5461                                        mc.moved_charge += HPAGE_PMD_NR;
5462                                }
5463                                putback_lru_page(page);
5464                        }
5465                        put_page(page);
5466                }
5467                spin_unlock(&vma->vm_mm->page_table_lock);
5468                return 0;
5469        }
5470
5471        if (pmd_trans_unstable(pmd))
5472                return 0;
5473retry:
5474        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
5475        for (; addr != end; addr += PAGE_SIZE) {
5476                pte_t ptent = *(pte++);
5477                swp_entry_t ent;
5478
5479                if (!mc.precharge)
5480                        break;
5481
5482                switch (get_mctgt_type(vma, addr, ptent, &target)) {
5483                case MC_TARGET_PAGE:
5484                        page = target.page;
5485                        if (isolate_lru_page(page))
5486                                goto put;
5487                        pc = lookup_page_cgroup(page);
5488                        if (!mem_cgroup_move_account(page, 1, pc,
5489                                                     mc.from, mc.to)) {
5490                                mc.precharge--;
5491                                /* we uncharge from mc.from later. */
5492                                mc.moved_charge++;
5493                        }
5494                        putback_lru_page(page);
5495put:                    /* get_mctgt_type() gets the page */
5496                        put_page(page);
5497                        break;
5498                case MC_TARGET_SWAP:
5499                        ent = target.ent;
5500                        if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
5501                                mc.precharge--;
5502                                /* we fixup refcnts and charges later. */
5503                                mc.moved_swap++;
5504                        }
5505                        break;
5506                default:
5507                        break;
5508                }
5509        }
5510        pte_unmap_unlock(pte - 1, ptl);
5511        cond_resched();
5512
5513        if (addr != end) {
5514                /*
5515                 * We have consumed all precharges we got in can_attach().
5516                 * We try charge one by one, but don't do any additional
5517                 * charges to mc.to if we have failed in charge once in attach()
5518                 * phase.
5519                 */
5520                ret = mem_cgroup_do_precharge(1);
5521                if (!ret)
5522                        goto retry;
5523        }
5524
5525        return ret;
5526}
5527
5528static void mem_cgroup_move_charge(struct mm_struct *mm)
5529{
5530        struct vm_area_struct *vma;
5531
5532        lru_add_drain_all();
5533retry:
5534        if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
5535                /*
5536                 * Someone who are holding the mmap_sem might be waiting in
5537                 * waitq. So we cancel all extra charges, wake up all waiters,
5538                 * and retry. Because we cancel precharges, we might not be able
5539                 * to move enough charges, but moving charge is a best-effort
5540                 * feature anyway, so it wouldn't be a big problem.
5541                 */
5542                __mem_cgroup_clear_mc();
5543                cond_resched();
5544                goto retry;
5545        }
5546        for (vma = mm->mmap; vma; vma = vma->vm_next) {
5547                int ret;
5548                struct mm_walk mem_cgroup_move_charge_walk = {
5549                        .pmd_entry = mem_cgroup_move_charge_pte_range,
5550                        .mm = mm,
5551                        .private = vma,
5552                };
5553                if (is_vm_hugetlb_page(vma))
5554                        continue;
5555                ret = walk_page_range(vma->vm_start, vma->vm_end,
5556                                                &mem_cgroup_move_charge_walk);
5557                if (ret)
5558                        /*
5559                         * means we have consumed all precharges and failed in
5560                         * doing additional charge. Just abandon here.
5561                         */
5562                        break;
5563        }
5564        up_read(&mm->mmap_sem);
5565}
5566
5567static void mem_cgroup_move_task(struct cgroup *cont,
5568                                 struct cgroup_taskset *tset)
5569{
5570        struct task_struct *p = cgroup_taskset_first(tset);
5571        struct mm_struct *mm = get_task_mm(p);
5572
5573        if (mm) {
5574                if (mc.to)
5575                        mem_cgroup_move_charge(mm);
5576                mmput(mm);
5577        }
5578        if (mc.to)
5579                mem_cgroup_clear_mc();
5580}
5581#else   /* !CONFIG_MMU */
5582static int mem_cgroup_can_attach(struct cgroup *cgroup,
5583                                 struct cgroup_taskset *tset)
5584{
5585        return 0;
5586}
5587static void mem_cgroup_cancel_attach(struct cgroup *cgroup,
5588                                     struct cgroup_taskset *tset)
5589{
5590}
5591static void mem_cgroup_move_task(struct cgroup *cont,
5592                                 struct cgroup_taskset *tset)
5593{
5594}
5595#endif
5596
5597struct cgroup_subsys mem_cgroup_subsys = {
5598        .name = "memory",
5599        .subsys_id = mem_cgroup_subsys_id,
5600        .create = mem_cgroup_create,
5601        .pre_destroy = mem_cgroup_pre_destroy,
5602        .destroy = mem_cgroup_destroy,
5603        .can_attach = mem_cgroup_can_attach,
5604        .cancel_attach = mem_cgroup_cancel_attach,
5605        .attach = mem_cgroup_move_task,
5606        .base_cftypes = mem_cgroup_files,
5607        .early_init = 0,
5608        .use_id = 1,
5609        .__DEPRECATED_clear_css_refs = true,
5610};
5611
5612#ifdef CONFIG_MEMCG_SWAP
5613static int __init enable_swap_account(char *s)
5614{
5615        /* consider enabled if no parameter or 1 is given */
5616        if (!strcmp(s, "1"))
5617                really_do_swap_account = 1;
5618        else if (!strcmp(s, "0"))
5619                really_do_swap_account = 0;
5620        return 1;
5621}
5622__setup("swapaccount=", enable_swap_account);
5623
5624#endif
5625
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