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 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License as published by
  11 * the Free Software Foundation; either version 2 of the License, or
  12 * (at your option) any later version.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 * GNU General Public License for more details.
  18 */
  19
  20#include <linux/res_counter.h>
  21#include <linux/memcontrol.h>
  22#include <linux/cgroup.h>
  23#include <linux/mm.h>
  24#include <linux/pagemap.h>
  25#include <linux/smp.h>
  26#include <linux/page-flags.h>
  27#include <linux/backing-dev.h>
  28#include <linux/bit_spinlock.h>
  29#include <linux/rcupdate.h>
  30#include <linux/mutex.h>
  31#include <linux/slab.h>
  32#include <linux/swap.h>
  33#include <linux/spinlock.h>
  34#include <linux/fs.h>
  35#include <linux/seq_file.h>
  36#include <linux/vmalloc.h>
  37#include <linux/mm_inline.h>
  38#include <linux/page_cgroup.h>
  39#include "internal.h"
  40
  41#include <asm/uaccess.h>
  42
  43struct cgroup_subsys mem_cgroup_subsys __read_mostly;
  44#define MEM_CGROUP_RECLAIM_RETRIES      5
  45
  46#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
  47/* Turned on only when memory cgroup is enabled && really_do_swap_account = 0 */
  48int do_swap_account __read_mostly;
  49static int really_do_swap_account __initdata = 1; /* for remember boot option*/
  50#else
  51#define do_swap_account         (0)
  52#endif
  53
  54static DEFINE_MUTEX(memcg_tasklist);    /* can be hold under cgroup_mutex */
  55
  56/*
  57 * Statistics for memory cgroup.
  58 */
  59enum mem_cgroup_stat_index {
  60        /*
  61         * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
  62         */
  63        MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
  64        MEM_CGROUP_STAT_RSS,       /* # of pages charged as rss */
  65        MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
  66        MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
  67
  68        MEM_CGROUP_STAT_NSTATS,
  69};
  70
  71struct mem_cgroup_stat_cpu {
  72        s64 count[MEM_CGROUP_STAT_NSTATS];
  73} ____cacheline_aligned_in_smp;
  74
  75struct mem_cgroup_stat {
  76        struct mem_cgroup_stat_cpu cpustat[0];
  77};
  78
  79/*
  80 * For accounting under irq disable, no need for increment preempt count.
  81 */
  82static inline void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat_cpu *stat,
  83                enum mem_cgroup_stat_index idx, int val)
  84{
  85        stat->count[idx] += val;
  86}
  87
  88static s64 mem_cgroup_read_stat(struct mem_cgroup_stat *stat,
  89                enum mem_cgroup_stat_index idx)
  90{
  91        int cpu;
  92        s64 ret = 0;
  93        for_each_possible_cpu(cpu)
  94                ret += stat->cpustat[cpu].count[idx];
  95        return ret;
  96}
  97
  98/*
  99 * per-zone information in memory controller.
 100 */
 101struct mem_cgroup_per_zone {
 102        /*
 103         * spin_lock to protect the per cgroup LRU
 104         */
 105        struct list_head        lists[NR_LRU_LISTS];
 106        unsigned long           count[NR_LRU_LISTS];
 107
 108        struct zone_reclaim_stat reclaim_stat;
 109};
 110/* Macro for accessing counter */
 111#define MEM_CGROUP_ZSTAT(mz, idx)       ((mz)->count[(idx)])
 112
 113struct mem_cgroup_per_node {
 114        struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
 115};
 116
 117struct mem_cgroup_lru_info {
 118        struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
 119};
 120
 121/*
 122 * The memory controller data structure. The memory controller controls both
 123 * page cache and RSS per cgroup. We would eventually like to provide
 124 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
 125 * to help the administrator determine what knobs to tune.
 126 *
 127 * TODO: Add a water mark for the memory controller. Reclaim will begin when
 128 * we hit the water mark. May be even add a low water mark, such that
 129 * no reclaim occurs from a cgroup at it's low water mark, this is
 130 * a feature that will be implemented much later in the future.
 131 */
 132struct mem_cgroup {
 133        struct cgroup_subsys_state css;
 134        /*
 135         * the counter to account for memory usage
 136         */
 137        struct res_counter res;
 138        /*
 139         * the counter to account for mem+swap usage.
 140         */
 141        struct res_counter memsw;
 142        /*
 143         * Per cgroup active and inactive list, similar to the
 144         * per zone LRU lists.
 145         */
 146        struct mem_cgroup_lru_info info;
 147
 148        /*
 149          protect against reclaim related member.
 150        */
 151        spinlock_t reclaim_param_lock;
 152
 153        int     prev_priority;  /* for recording reclaim priority */
 154
 155        /*
 156         * While reclaiming in a hiearchy, we cache the last child we
 157         * reclaimed from. Protected by hierarchy_mutex
 158         */
 159        struct mem_cgroup *last_scanned_child;
 160        /*
 161         * Should the accounting and control be hierarchical, per subtree?
 162         */
 163        bool use_hierarchy;
 164        unsigned long   last_oom_jiffies;
 165        atomic_t        refcnt;
 166
 167        unsigned int    swappiness;
 168
 169        /*
 170         * statistics. This must be placed at the end of memcg.
 171         */
 172        struct mem_cgroup_stat stat;
 173};
 174
 175enum charge_type {
 176        MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
 177        MEM_CGROUP_CHARGE_TYPE_MAPPED,
 178        MEM_CGROUP_CHARGE_TYPE_SHMEM,   /* used by page migration of shmem */
 179        MEM_CGROUP_CHARGE_TYPE_FORCE,   /* used by force_empty */
 180        MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
 181        NR_CHARGE_TYPE,
 182};
 183
 184/* only for here (for easy reading.) */
 185#define PCGF_CACHE      (1UL << PCG_CACHE)
 186#define PCGF_USED       (1UL << PCG_USED)
 187#define PCGF_LOCK       (1UL << PCG_LOCK)
 188static const unsigned long
 189pcg_default_flags[NR_CHARGE_TYPE] = {
 190        PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* File Cache */
 191        PCGF_USED | PCGF_LOCK, /* Anon */
 192        PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* Shmem */
 193        0, /* FORCE */
 194};
 195
 196/* for encoding cft->private value on file */
 197#define _MEM                    (0)
 198#define _MEMSWAP                (1)
 199#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
 200#define MEMFILE_TYPE(val)       (((val) >> 16) & 0xffff)
 201#define MEMFILE_ATTR(val)       ((val) & 0xffff)
 202
 203static void mem_cgroup_get(struct mem_cgroup *mem);
 204static void mem_cgroup_put(struct mem_cgroup *mem);
 205static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
 206
 207static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
 208                                         struct page_cgroup *pc,
 209                                         bool charge)
 210{
 211        int val = (charge)? 1 : -1;
 212        struct mem_cgroup_stat *stat = &mem->stat;
 213        struct mem_cgroup_stat_cpu *cpustat;
 214        int cpu = get_cpu();
 215
 216        cpustat = &stat->cpustat[cpu];
 217        if (PageCgroupCache(pc))
 218                __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
 219        else
 220                __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS, val);
 221
 222        if (charge)
 223                __mem_cgroup_stat_add_safe(cpustat,
 224                                MEM_CGROUP_STAT_PGPGIN_COUNT, 1);
 225        else
 226                __mem_cgroup_stat_add_safe(cpustat,
 227                                MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
 228        put_cpu();
 229}
 230
 231static struct mem_cgroup_per_zone *
 232mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
 233{
 234        return &mem->info.nodeinfo[nid]->zoneinfo[zid];
 235}
 236
 237static struct mem_cgroup_per_zone *
 238page_cgroup_zoneinfo(struct page_cgroup *pc)
 239{
 240        struct mem_cgroup *mem = pc->mem_cgroup;
 241        int nid = page_cgroup_nid(pc);
 242        int zid = page_cgroup_zid(pc);
 243
 244        if (!mem)
 245                return NULL;
 246
 247        return mem_cgroup_zoneinfo(mem, nid, zid);
 248}
 249
 250static unsigned long mem_cgroup_get_all_zonestat(struct mem_cgroup *mem,
 251                                        enum lru_list idx)
 252{
 253        int nid, zid;
 254        struct mem_cgroup_per_zone *mz;
 255        u64 total = 0;
 256
 257        for_each_online_node(nid)
 258                for (zid = 0; zid < MAX_NR_ZONES; zid++) {
 259                        mz = mem_cgroup_zoneinfo(mem, nid, zid);
 260                        total += MEM_CGROUP_ZSTAT(mz, idx);
 261                }
 262        return total;
 263}
 264
 265static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 266{
 267        return container_of(cgroup_subsys_state(cont,
 268                                mem_cgroup_subsys_id), struct mem_cgroup,
 269                                css);
 270}
 271
 272struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 273{
 274        /*
 275         * mm_update_next_owner() may clear mm->owner to NULL
 276         * if it races with swapoff, page migration, etc.
 277         * So this can be called with p == NULL.
 278         */
 279        if (unlikely(!p))
 280                return NULL;
 281
 282        return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
 283                                struct mem_cgroup, css);
 284}
 285
 286static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 287{
 288        struct mem_cgroup *mem = NULL;
 289        /*
 290         * Because we have no locks, mm->owner's may be being moved to other
 291         * cgroup. We use css_tryget() here even if this looks
 292         * pessimistic (rather than adding locks here).
 293         */
 294        rcu_read_lock();
 295        do {
 296                mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
 297                if (unlikely(!mem))
 298                        break;
 299        } while (!css_tryget(&mem->css));
 300        rcu_read_unlock();
 301        return mem;
 302}
 303
 304static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem)
 305{
 306        if (!mem)
 307                return true;
 308        return css_is_removed(&mem->css);
 309}
 310
 311/*
 312 * Following LRU functions are allowed to be used without PCG_LOCK.
 313 * Operations are called by routine of global LRU independently from memcg.
 314 * What we have to take care of here is validness of pc->mem_cgroup.
 315 *
 316 * Changes to pc->mem_cgroup happens when
 317 * 1. charge
 318 * 2. moving account
 319 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
 320 * It is added to LRU before charge.
 321 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
 322 * When moving account, the page is not on LRU. It's isolated.
 323 */
 324
 325void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
 326{
 327        struct page_cgroup *pc;
 328        struct mem_cgroup *mem;
 329        struct mem_cgroup_per_zone *mz;
 330
 331        if (mem_cgroup_disabled())
 332                return;
 333        pc = lookup_page_cgroup(page);
 334        /* can happen while we handle swapcache. */
 335        if (list_empty(&pc->lru) || !pc->mem_cgroup)
 336                return;
 337        /*
 338         * We don't check PCG_USED bit. It's cleared when the "page" is finally
 339         * removed from global LRU.
 340         */
 341        mz = page_cgroup_zoneinfo(pc);
 342        mem = pc->mem_cgroup;
 343        MEM_CGROUP_ZSTAT(mz, lru) -= 1;
 344        list_del_init(&pc->lru);
 345        return;
 346}
 347
 348void mem_cgroup_del_lru(struct page *page)
 349{
 350        mem_cgroup_del_lru_list(page, page_lru(page));
 351}
 352
 353void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
 354{
 355        struct mem_cgroup_per_zone *mz;
 356        struct page_cgroup *pc;
 357
 358        if (mem_cgroup_disabled())
 359                return;
 360
 361        pc = lookup_page_cgroup(page);
 362        /*
 363         * Used bit is set without atomic ops but after smp_wmb().
 364         * For making pc->mem_cgroup visible, insert smp_rmb() here.
 365         */
 366        smp_rmb();
 367        /* unused page is not rotated. */
 368        if (!PageCgroupUsed(pc))
 369                return;
 370        mz = page_cgroup_zoneinfo(pc);
 371        list_move(&pc->lru, &mz->lists[lru]);
 372}
 373
 374void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
 375{
 376        struct page_cgroup *pc;
 377        struct mem_cgroup_per_zone *mz;
 378
 379        if (mem_cgroup_disabled())
 380                return;
 381        pc = lookup_page_cgroup(page);
 382        /*
 383         * Used bit is set without atomic ops but after smp_wmb().
 384         * For making pc->mem_cgroup visible, insert smp_rmb() here.
 385         */
 386        smp_rmb();
 387        if (!PageCgroupUsed(pc))
 388                return;
 389
 390        mz = page_cgroup_zoneinfo(pc);
 391        MEM_CGROUP_ZSTAT(mz, lru) += 1;
 392        list_add(&pc->lru, &mz->lists[lru]);
 393}
 394
 395/*
 396 * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
 397 * lru because the page may.be reused after it's fully uncharged (because of
 398 * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
 399 * it again. This function is only used to charge SwapCache. It's done under
 400 * lock_page and expected that zone->lru_lock is never held.
 401 */
 402static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
 403{
 404        unsigned long flags;
 405        struct zone *zone = page_zone(page);
 406        struct page_cgroup *pc = lookup_page_cgroup(page);
 407
 408        spin_lock_irqsave(&zone->lru_lock, flags);
 409        /*
 410         * Forget old LRU when this page_cgroup is *not* used. This Used bit
 411         * is guarded by lock_page() because the page is SwapCache.
 412         */
 413        if (!PageCgroupUsed(pc))
 414                mem_cgroup_del_lru_list(page, page_lru(page));
 415        spin_unlock_irqrestore(&zone->lru_lock, flags);
 416}
 417
 418static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
 419{
 420        unsigned long flags;
 421        struct zone *zone = page_zone(page);
 422        struct page_cgroup *pc = lookup_page_cgroup(page);
 423
 424        spin_lock_irqsave(&zone->lru_lock, flags);
 425        /* link when the page is linked to LRU but page_cgroup isn't */
 426        if (PageLRU(page) && list_empty(&pc->lru))
 427                mem_cgroup_add_lru_list(page, page_lru(page));
 428        spin_unlock_irqrestore(&zone->lru_lock, flags);
 429}
 430
 431
 432void mem_cgroup_move_lists(struct page *page,
 433                           enum lru_list from, enum lru_list to)
 434{
 435        if (mem_cgroup_disabled())
 436                return;
 437        mem_cgroup_del_lru_list(page, from);
 438        mem_cgroup_add_lru_list(page, to);
 439}
 440
 441int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
 442{
 443        int ret;
 444
 445        task_lock(task);
 446        ret = task->mm && mm_match_cgroup(task->mm, mem);
 447        task_unlock(task);
 448        return ret;
 449}
 450
 451/*
 452 * Calculate mapped_ratio under memory controller. This will be used in
 453 * vmscan.c for deteremining we have to reclaim mapped pages.
 454 */
 455int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem)
 456{
 457        long total, rss;
 458
 459        /*
 460         * usage is recorded in bytes. But, here, we assume the number of
 461         * physical pages can be represented by "long" on any arch.
 462         */
 463        total = (long) (mem->res.usage >> PAGE_SHIFT) + 1L;
 464        rss = (long)mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_RSS);
 465        return (int)((rss * 100L) / total);
 466}
 467
 468/*
 469 * prev_priority control...this will be used in memory reclaim path.
 470 */
 471int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
 472{
 473        int prev_priority;
 474
 475        spin_lock(&mem->reclaim_param_lock);
 476        prev_priority = mem->prev_priority;
 477        spin_unlock(&mem->reclaim_param_lock);
 478
 479        return prev_priority;
 480}
 481
 482void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority)
 483{
 484        spin_lock(&mem->reclaim_param_lock);
 485        if (priority < mem->prev_priority)
 486                mem->prev_priority = priority;
 487        spin_unlock(&mem->reclaim_param_lock);
 488}
 489
 490void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
 491{
 492        spin_lock(&mem->reclaim_param_lock);
 493        mem->prev_priority = priority;
 494        spin_unlock(&mem->reclaim_param_lock);
 495}
 496
 497static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
 498{
 499        unsigned long active;
 500        unsigned long inactive;
 501        unsigned long gb;
 502        unsigned long inactive_ratio;
 503
 504        inactive = mem_cgroup_get_all_zonestat(memcg, LRU_INACTIVE_ANON);
 505        active = mem_cgroup_get_all_zonestat(memcg, LRU_ACTIVE_ANON);
 506
 507        gb = (inactive + active) >> (30 - PAGE_SHIFT);
 508        if (gb)
 509                inactive_ratio = int_sqrt(10 * gb);
 510        else
 511                inactive_ratio = 1;
 512
 513        if (present_pages) {
 514                present_pages[0] = inactive;
 515                present_pages[1] = active;
 516        }
 517
 518        return inactive_ratio;
 519}
 520
 521int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
 522{
 523        unsigned long active;
 524        unsigned long inactive;
 525        unsigned long present_pages[2];
 526        unsigned long inactive_ratio;
 527
 528        inactive_ratio = calc_inactive_ratio(memcg, present_pages);
 529
 530        inactive = present_pages[0];
 531        active = present_pages[1];
 532
 533        if (inactive * inactive_ratio < active)
 534                return 1;
 535
 536        return 0;
 537}
 538
 539unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
 540                                       struct zone *zone,
 541                                       enum lru_list lru)
 542{
 543        int nid = zone->zone_pgdat->node_id;
 544        int zid = zone_idx(zone);
 545        struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
 546
 547        return MEM_CGROUP_ZSTAT(mz, lru);
 548}
 549
 550struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
 551                                                      struct zone *zone)
 552{
 553        int nid = zone->zone_pgdat->node_id;
 554        int zid = zone_idx(zone);
 555        struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
 556
 557        return &mz->reclaim_stat;
 558}
 559
 560struct zone_reclaim_stat *
 561mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 562{
 563        struct page_cgroup *pc;
 564        struct mem_cgroup_per_zone *mz;
 565
 566        if (mem_cgroup_disabled())
 567                return NULL;
 568
 569        pc = lookup_page_cgroup(page);
 570        /*
 571         * Used bit is set without atomic ops but after smp_wmb().
 572         * For making pc->mem_cgroup visible, insert smp_rmb() here.
 573         */
 574        smp_rmb();
 575        if (!PageCgroupUsed(pc))
 576                return NULL;
 577
 578        mz = page_cgroup_zoneinfo(pc);
 579        if (!mz)
 580                return NULL;
 581
 582        return &mz->reclaim_stat;
 583}
 584
 585unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 586                                        struct list_head *dst,
 587                                        unsigned long *scanned, int order,
 588                                        int mode, struct zone *z,
 589                                        struct mem_cgroup *mem_cont,
 590                                        int active, int file)
 591{
 592        unsigned long nr_taken = 0;
 593        struct page *page;
 594        unsigned long scan;
 595        LIST_HEAD(pc_list);
 596        struct list_head *src;
 597        struct page_cgroup *pc, *tmp;
 598        int nid = z->zone_pgdat->node_id;
 599        int zid = zone_idx(z);
 600        struct mem_cgroup_per_zone *mz;
 601        int lru = LRU_FILE * !!file + !!active;
 602
 603        BUG_ON(!mem_cont);
 604        mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
 605        src = &mz->lists[lru];
 606
 607        scan = 0;
 608        list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
 609                if (scan >= nr_to_scan)
 610                        break;
 611
 612                page = pc->page;
 613                if (unlikely(!PageCgroupUsed(pc)))
 614                        continue;
 615                if (unlikely(!PageLRU(page)))
 616                        continue;
 617
 618                scan++;
 619                if (__isolate_lru_page(page, mode, file) == 0) {
 620                        list_move(&page->lru, dst);
 621                        nr_taken++;
 622                }
 623        }
 624
 625        *scanned = scan;
 626        return nr_taken;
 627}
 628
 629#define mem_cgroup_from_res_counter(counter, member)    \
 630        container_of(counter, struct mem_cgroup, member)
 631
 632/*
 633 * This routine finds the DFS walk successor. This routine should be
 634 * called with hierarchy_mutex held
 635 */
 636static struct mem_cgroup *
 637__mem_cgroup_get_next_node(struct mem_cgroup *curr, struct mem_cgroup *root_mem)
 638{
 639        struct cgroup *cgroup, *curr_cgroup, *root_cgroup;
 640
 641        curr_cgroup = curr->css.cgroup;
 642        root_cgroup = root_mem->css.cgroup;
 643
 644        if (!list_empty(&curr_cgroup->children)) {
 645                /*
 646                 * Walk down to children
 647                 */
 648                cgroup = list_entry(curr_cgroup->children.next,
 649                                                struct cgroup, sibling);
 650                curr = mem_cgroup_from_cont(cgroup);
 651                goto done;
 652        }
 653
 654visit_parent:
 655        if (curr_cgroup == root_cgroup) {
 656                /* caller handles NULL case */
 657                curr = NULL;
 658                goto done;
 659        }
 660
 661        /*
 662         * Goto next sibling
 663         */
 664        if (curr_cgroup->sibling.next != &curr_cgroup->parent->children) {
 665                cgroup = list_entry(curr_cgroup->sibling.next, struct cgroup,
 666                                                sibling);
 667                curr = mem_cgroup_from_cont(cgroup);
 668                goto done;
 669        }
 670
 671        /*
 672         * Go up to next parent and next parent's sibling if need be
 673         */
 674        curr_cgroup = curr_cgroup->parent;
 675        goto visit_parent;
 676
 677done:
 678        return curr;
 679}
 680
 681/*
 682 * Visit the first child (need not be the first child as per the ordering
 683 * of the cgroup list, since we track last_scanned_child) of @mem and use
 684 * that to reclaim free pages from.
 685 */
 686static struct mem_cgroup *
 687mem_cgroup_get_next_node(struct mem_cgroup *root_mem)
 688{
 689        struct cgroup *cgroup;
 690        struct mem_cgroup *orig, *next;
 691        bool obsolete;
 692
 693        /*
 694         * Scan all children under the mem_cgroup mem
 695         */
 696        mutex_lock(&mem_cgroup_subsys.hierarchy_mutex);
 697
 698        orig = root_mem->last_scanned_child;
 699        obsolete = mem_cgroup_is_obsolete(orig);
 700
 701        if (list_empty(&root_mem->css.cgroup->children)) {
 702                /*
 703                 * root_mem might have children before and last_scanned_child
 704                 * may point to one of them. We put it later.
 705                 */
 706                if (orig)
 707                        VM_BUG_ON(!obsolete);
 708                next = NULL;
 709                goto done;
 710        }
 711
 712        if (!orig || obsolete) {
 713                cgroup = list_first_entry(&root_mem->css.cgroup->children,
 714                                struct cgroup, sibling);
 715                next = mem_cgroup_from_cont(cgroup);
 716        } else
 717                next = __mem_cgroup_get_next_node(orig, root_mem);
 718
 719done:
 720        if (next)
 721                mem_cgroup_get(next);
 722        root_mem->last_scanned_child = next;
 723        if (orig)
 724                mem_cgroup_put(orig);
 725        mutex_unlock(&mem_cgroup_subsys.hierarchy_mutex);
 726        return (next) ? next : root_mem;
 727}
 728
 729static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
 730{
 731        if (do_swap_account) {
 732                if (res_counter_check_under_limit(&mem->res) &&
 733                        res_counter_check_under_limit(&mem->memsw))
 734                        return true;
 735        } else
 736                if (res_counter_check_under_limit(&mem->res))
 737                        return true;
 738        return false;
 739}
 740
 741static unsigned int get_swappiness(struct mem_cgroup *memcg)
 742{
 743        struct cgroup *cgrp = memcg->css.cgroup;
 744        unsigned int swappiness;
 745
 746        /* root ? */
 747        if (cgrp->parent == NULL)
 748                return vm_swappiness;
 749
 750        spin_lock(&memcg->reclaim_param_lock);
 751        swappiness = memcg->swappiness;
 752        spin_unlock(&memcg->reclaim_param_lock);
 753
 754        return swappiness;
 755}
 756
 757/*
 758 * Dance down the hierarchy if needed to reclaim memory. We remember the
 759 * last child we reclaimed from, so that we don't end up penalizing
 760 * one child extensively based on its position in the children list.
 761 *
 762 * root_mem is the original ancestor that we've been reclaim from.
 763 */
 764static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
 765                                                gfp_t gfp_mask, bool noswap)
 766{
 767        struct mem_cgroup *next_mem;
 768        int ret = 0;
 769
 770        /*
 771         * Reclaim unconditionally and don't check for return value.
 772         * We need to reclaim in the current group and down the tree.
 773         * One might think about checking for children before reclaiming,
 774         * but there might be left over accounting, even after children
 775         * have left.
 776         */
 777        ret += try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap,
 778                                           get_swappiness(root_mem));
 779        if (mem_cgroup_check_under_limit(root_mem))
 780                return 1;       /* indicate reclaim has succeeded */
 781        if (!root_mem->use_hierarchy)
 782                return ret;
 783
 784        next_mem = mem_cgroup_get_next_node(root_mem);
 785
 786        while (next_mem != root_mem) {
 787                if (mem_cgroup_is_obsolete(next_mem)) {
 788                        next_mem = mem_cgroup_get_next_node(root_mem);
 789                        continue;
 790                }
 791                ret += try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap,
 792                                                   get_swappiness(next_mem));
 793                if (mem_cgroup_check_under_limit(root_mem))
 794                        return 1;       /* indicate reclaim has succeeded */
 795                next_mem = mem_cgroup_get_next_node(root_mem);
 796        }
 797        return ret;
 798}
 799
 800bool mem_cgroup_oom_called(struct task_struct *task)
 801{
 802        bool ret = false;
 803        struct mem_cgroup *mem;
 804        struct mm_struct *mm;
 805
 806        rcu_read_lock();
 807        mm = task->mm;
 808        if (!mm)
 809                mm = &init_mm;
 810        mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
 811        if (mem && time_before(jiffies, mem->last_oom_jiffies + HZ/10))
 812                ret = true;
 813        rcu_read_unlock();
 814        return ret;
 815}
 816/*
 817 * Unlike exported interface, "oom" parameter is added. if oom==true,
 818 * oom-killer can be invoked.
 819 */
 820static int __mem_cgroup_try_charge(struct mm_struct *mm,
 821                        gfp_t gfp_mask, struct mem_cgroup **memcg,
 822                        bool oom)
 823{
 824        struct mem_cgroup *mem, *mem_over_limit;
 825        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 826        struct res_counter *fail_res;
 827
 828        if (unlikely(test_thread_flag(TIF_MEMDIE))) {
 829                /* Don't account this! */
 830                *memcg = NULL;
 831                return 0;
 832        }
 833
 834        /*
 835         * We always charge the cgroup the mm_struct belongs to.
 836         * The mm_struct's mem_cgroup changes on task migration if the
 837         * thread group leader migrates. It's possible that mm is not
 838         * set, if so charge the init_mm (happens for pagecache usage).
 839         */
 840        mem = *memcg;
 841        if (likely(!mem)) {
 842                mem = try_get_mem_cgroup_from_mm(mm);
 843                *memcg = mem;
 844        } else {
 845                css_get(&mem->css);
 846        }
 847        if (unlikely(!mem))
 848                return 0;
 849
 850        VM_BUG_ON(mem_cgroup_is_obsolete(mem));
 851
 852        while (1) {
 853                int ret;
 854                bool noswap = false;
 855
 856                ret = res_counter_charge(&mem->res, PAGE_SIZE, &fail_res);
 857                if (likely(!ret)) {
 858                        if (!do_swap_account)
 859                                break;
 860                        ret = res_counter_charge(&mem->memsw, PAGE_SIZE,
 861                                                        &fail_res);
 862                        if (likely(!ret))
 863                                break;
 864                        /* mem+swap counter fails */
 865                        res_counter_uncharge(&mem->res, PAGE_SIZE);
 866                        noswap = true;
 867                        mem_over_limit = mem_cgroup_from_res_counter(fail_res,
 868                                                                        memsw);
 869                } else
 870                        /* mem counter fails */
 871                        mem_over_limit = mem_cgroup_from_res_counter(fail_res,
 872                                                                        res);
 873
 874                if (!(gfp_mask & __GFP_WAIT))
 875                        goto nomem;
 876
 877                ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, gfp_mask,
 878                                                        noswap);
 879                if (ret)
 880                        continue;
 881
 882                /*
 883                 * try_to_free_mem_cgroup_pages() might not give us a full
 884                 * picture of reclaim. Some pages are reclaimed and might be
 885                 * moved to swap cache or just unmapped from the cgroup.
 886                 * Check the limit again to see if the reclaim reduced the
 887                 * current usage of the cgroup before giving up
 888                 *
 889                 */
 890                if (mem_cgroup_check_under_limit(mem_over_limit))
 891                        continue;
 892
 893                if (!nr_retries--) {
 894                        if (oom) {
 895                                mutex_lock(&memcg_tasklist);
 896                                mem_cgroup_out_of_memory(mem_over_limit, gfp_mask);
 897                                mutex_unlock(&memcg_tasklist);
 898                                mem_over_limit->last_oom_jiffies = jiffies;
 899                        }
 900                        goto nomem;
 901                }
 902        }
 903        return 0;
 904nomem:
 905        css_put(&mem->css);
 906        return -ENOMEM;
 907}
 908
 909static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
 910{
 911        struct mem_cgroup *mem;
 912        swp_entry_t ent;
 913
 914        if (!PageSwapCache(page))
 915                return NULL;
 916
 917        ent.val = page_private(page);
 918        mem = lookup_swap_cgroup(ent);
 919        if (!mem)
 920                return NULL;
 921        if (!css_tryget(&mem->css))
 922                return NULL;
 923        return mem;
 924}
 925
 926/*
 927 * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
 928 * USED state. If already USED, uncharge and return.
 929 */
 930
 931static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
 932                                     struct page_cgroup *pc,
 933                                     enum charge_type ctype)
 934{
 935        /* try_charge() can return NULL to *memcg, taking care of it. */
 936        if (!mem)
 937                return;
 938
 939        lock_page_cgroup(pc);
 940        if (unlikely(PageCgroupUsed(pc))) {
 941                unlock_page_cgroup(pc);
 942                res_counter_uncharge(&mem->res, PAGE_SIZE);
 943                if (do_swap_account)
 944                        res_counter_uncharge(&mem->memsw, PAGE_SIZE);
 945                css_put(&mem->css);
 946                return;
 947        }
 948        pc->mem_cgroup = mem;
 949        smp_wmb();
 950        pc->flags = pcg_default_flags[ctype];
 951
 952        mem_cgroup_charge_statistics(mem, pc, true);
 953
 954        unlock_page_cgroup(pc);
 955}
 956
 957/**
 958 * mem_cgroup_move_account - move account of the page
 959 * @pc: page_cgroup of the page.
 960 * @from: mem_cgroup which the page is moved from.
 961 * @to: mem_cgroup which the page is moved to. @from != @to.
 962 *
 963 * The caller must confirm following.
 964 * - page is not on LRU (isolate_page() is useful.)
 965 *
 966 * returns 0 at success,
 967 * returns -EBUSY when lock is busy or "pc" is unstable.
 968 *
 969 * This function does "uncharge" from old cgroup but doesn't do "charge" to
 970 * new cgroup. It should be done by a caller.
 971 */
 972
 973static int mem_cgroup_move_account(struct page_cgroup *pc,
 974        struct mem_cgroup *from, struct mem_cgroup *to)
 975{
 976        struct mem_cgroup_per_zone *from_mz, *to_mz;
 977        int nid, zid;
 978        int ret = -EBUSY;
 979
 980        VM_BUG_ON(from == to);
 981        VM_BUG_ON(PageLRU(pc->page));
 982
 983        nid = page_cgroup_nid(pc);
 984        zid = page_cgroup_zid(pc);
 985        from_mz =  mem_cgroup_zoneinfo(from, nid, zid);
 986        to_mz =  mem_cgroup_zoneinfo(to, nid, zid);
 987
 988        if (!trylock_page_cgroup(pc))
 989                return ret;
 990
 991        if (!PageCgroupUsed(pc))
 992                goto out;
 993
 994        if (pc->mem_cgroup != from)
 995                goto out;
 996
 997        res_counter_uncharge(&from->res, PAGE_SIZE);
 998        mem_cgroup_charge_statistics(from, pc, false);
 999        if (do_swap_account)
1000                res_counter_uncharge(&from->memsw, PAGE_SIZE);
1001        css_put(&from->css);
1002
1003        css_get(&to->css);
1004        pc->mem_cgroup = to;
1005        mem_cgroup_charge_statistics(to, pc, true);
1006        ret = 0;
1007out:
1008        unlock_page_cgroup(pc);
1009        return ret;
1010}
1011
1012/*
1013 * move charges to its parent.
1014 */
1015
1016static int mem_cgroup_move_parent(struct page_cgroup *pc,
1017                                  struct mem_cgroup *child,
1018                                  gfp_t gfp_mask)
1019{
1020        struct page *page = pc->page;
1021        struct cgroup *cg = child->css.cgroup;
1022        struct cgroup *pcg = cg->parent;
1023        struct mem_cgroup *parent;
1024        int ret;
1025
1026        /* Is ROOT ? */
1027        if (!pcg)
1028                return -EINVAL;
1029
1030
1031        parent = mem_cgroup_from_cont(pcg);
1032
1033
1034        ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
1035        if (ret || !parent)
1036                return ret;
1037
1038        if (!get_page_unless_zero(page)) {
1039                ret = -EBUSY;
1040                goto uncharge;
1041        }
1042
1043        ret = isolate_lru_page(page);
1044
1045        if (ret)
1046                goto cancel;
1047
1048        ret = mem_cgroup_move_account(pc, child, parent);
1049
1050        putback_lru_page(page);
1051        if (!ret) {
1052                put_page(page);
1053                /* drop extra refcnt by try_charge() */
1054                css_put(&parent->css);
1055                return 0;
1056        }
1057
1058cancel:
1059        put_page(page);
1060uncharge:
1061        /* drop extra refcnt by try_charge() */
1062        css_put(&parent->css);
1063        /* uncharge if move fails */
1064        res_counter_uncharge(&parent->res, PAGE_SIZE);
1065        if (do_swap_account)
1066                res_counter_uncharge(&parent->memsw, PAGE_SIZE);
1067        return ret;
1068}
1069
1070/*
1071 * Charge the memory controller for page usage.
1072 * Return
1073 * 0 if the charge was successful
1074 * < 0 if the cgroup is over its limit
1075 */
1076static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
1077                                gfp_t gfp_mask, enum charge_type ctype,
1078                                struct mem_cgroup *memcg)
1079{
1080        struct mem_cgroup *mem;
1081        struct page_cgroup *pc;
1082        int ret;
1083
1084        pc = lookup_page_cgroup(page);
1085        /* can happen at boot */
1086        if (unlikely(!pc))
1087                return 0;
1088        prefetchw(pc);
1089
1090        mem = memcg;
1091        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
1092        if (ret || !mem)
1093                return ret;
1094
1095        __mem_cgroup_commit_charge(mem, pc, ctype);
1096        return 0;
1097}
1098
1099int mem_cgroup_newpage_charge(struct page *page,
1100                              struct mm_struct *mm, gfp_t gfp_mask)
1101{
1102        if (mem_cgroup_disabled())
1103                return 0;
1104        if (PageCompound(page))
1105                return 0;
1106        /*
1107         * If already mapped, we don't have to account.
1108         * If page cache, page->mapping has address_space.
1109         * But page->mapping may have out-of-use anon_vma pointer,
1110         * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
1111         * is NULL.
1112         */
1113        if (page_mapped(page) || (page->mapping && !PageAnon(page)))
1114                return 0;
1115        if (unlikely(!mm))
1116                mm = &init_mm;
1117        return mem_cgroup_charge_common(page, mm, gfp_mask,
1118                                MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
1119}
1120
1121int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
1122                                gfp_t gfp_mask)
1123{
1124        struct mem_cgroup *mem = NULL;
1125        int ret;
1126
1127        if (mem_cgroup_disabled())
1128                return 0;
1129        if (PageCompound(page))
1130                return 0;
1131        /*
1132         * Corner case handling. This is called from add_to_page_cache()
1133         * in usual. But some FS (shmem) precharges this page before calling it
1134         * and call add_to_page_cache() with GFP_NOWAIT.
1135         *
1136         * For GFP_NOWAIT case, the page may be pre-charged before calling
1137         * add_to_page_cache(). (See shmem.c) check it here and avoid to call
1138         * charge twice. (It works but has to pay a bit larger cost.)
1139         * And when the page is SwapCache, it should take swap information
1140         * into account. This is under lock_page() now.
1141         */
1142        if (!(gfp_mask & __GFP_WAIT)) {
1143                struct page_cgroup *pc;
1144
1145
1146                pc = lookup_page_cgroup(page);
1147                if (!pc)
1148                        return 0;
1149                lock_page_cgroup(pc);
1150                if (PageCgroupUsed(pc)) {
1151                        unlock_page_cgroup(pc);
1152                        return 0;
1153                }
1154                unlock_page_cgroup(pc);
1155        }
1156
1157        if (do_swap_account && PageSwapCache(page)) {
1158                mem = try_get_mem_cgroup_from_swapcache(page);
1159                if (mem)
1160                        mm = NULL;
1161                  else
1162                        mem = NULL;
1163                /* SwapCache may be still linked to LRU now. */
1164                mem_cgroup_lru_del_before_commit_swapcache(page);
1165        }
1166
1167        if (unlikely(!mm && !mem))
1168                mm = &init_mm;
1169
1170        if (page_is_file_cache(page))
1171                return mem_cgroup_charge_common(page, mm, gfp_mask,
1172                                MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
1173
1174        ret = mem_cgroup_charge_common(page, mm, gfp_mask,
1175                                MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
1176        if (mem)
1177                css_put(&mem->css);
1178        if (PageSwapCache(page))
1179                mem_cgroup_lru_add_after_commit_swapcache(page);
1180
1181        if (do_swap_account && !ret && PageSwapCache(page)) {
1182                swp_entry_t ent = {.val = page_private(page)};
1183                /* avoid double counting */
1184                mem = swap_cgroup_record(ent, NULL);
1185                if (mem) {
1186                        res_counter_uncharge(&mem->memsw, PAGE_SIZE);
1187                        mem_cgroup_put(mem);
1188                }
1189        }
1190        return ret;
1191}
1192
1193/*
1194 * While swap-in, try_charge -> commit or cancel, the page is locked.
1195 * And when try_charge() successfully returns, one refcnt to memcg without
1196 * struct page_cgroup is aquired. This refcnt will be cumsumed by
1197 * "commit()" or removed by "cancel()"
1198 */
1199int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
1200                                 struct page *page,
1201                                 gfp_t mask, struct mem_cgroup **ptr)
1202{
1203        struct mem_cgroup *mem;
1204        int ret;
1205
1206        if (mem_cgroup_disabled())
1207                return 0;
1208
1209        if (!do_swap_account)
1210                goto charge_cur_mm;
1211        /*
1212         * A racing thread's fault, or swapoff, may have already updated
1213         * the pte, and even removed page from swap cache: return success
1214         * to go on to do_swap_page()'s pte_same() test, which should fail.
1215         */
1216        if (!PageSwapCache(page))
1217                return 0;
1218        mem = try_get_mem_cgroup_from_swapcache(page);
1219        if (!mem)
1220                goto charge_cur_mm;
1221        *ptr = mem;
1222        ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
1223        /* drop extra refcnt from tryget */
1224        css_put(&mem->css);
1225        return ret;
1226charge_cur_mm:
1227        if (unlikely(!mm))
1228                mm = &init_mm;
1229        return __mem_cgroup_try_charge(mm, mask, ptr, true);
1230}
1231
1232void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
1233{
1234        struct page_cgroup *pc;
1235
1236        if (mem_cgroup_disabled())
1237                return;
1238        if (!ptr)
1239                return;
1240        pc = lookup_page_cgroup(page);
1241        mem_cgroup_lru_del_before_commit_swapcache(page);
1242        __mem_cgroup_commit_charge(ptr, pc, MEM_CGROUP_CHARGE_TYPE_MAPPED);
1243        mem_cgroup_lru_add_after_commit_swapcache(page);
1244        /*
1245         * Now swap is on-memory. This means this page may be
1246         * counted both as mem and swap....double count.
1247         * Fix it by uncharging from memsw. Basically, this SwapCache is stable
1248         * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
1249         * may call delete_from_swap_cache() before reach here.
1250         */
1251        if (do_swap_account && PageSwapCache(page)) {
1252                swp_entry_t ent = {.val = page_private(page)};
1253                struct mem_cgroup *memcg;
1254                memcg = swap_cgroup_record(ent, NULL);
1255                if (memcg) {
1256                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
1257                        mem_cgroup_put(memcg);
1258                }
1259
1260        }
1261        /* add this page(page_cgroup) to the LRU we want. */
1262
1263}
1264
1265void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
1266{
1267        if (mem_cgroup_disabled())
1268                return;
1269        if (!mem)
1270                return;
1271        res_counter_uncharge(&mem->res, PAGE_SIZE);
1272        if (do_swap_account)
1273                res_counter_uncharge(&mem->memsw, PAGE_SIZE);
1274        css_put(&mem->css);
1275}
1276
1277
1278/*
1279 * uncharge if !page_mapped(page)
1280 */
1281static struct mem_cgroup *
1282__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
1283{
1284        struct page_cgroup *pc;
1285        struct mem_cgroup *mem = NULL;
1286        struct mem_cgroup_per_zone *mz;
1287
1288        if (mem_cgroup_disabled())
1289                return NULL;
1290
1291        if (PageSwapCache(page))
1292                return NULL;
1293
1294        /*
1295         * Check if our page_cgroup is valid
1296         */
1297        pc = lookup_page_cgroup(page);
1298        if (unlikely(!pc || !PageCgroupUsed(pc)))
1299                return NULL;
1300
1301        lock_page_cgroup(pc);
1302
1303        mem = pc->mem_cgroup;
1304
1305        if (!PageCgroupUsed(pc))
1306                goto unlock_out;
1307
1308        switch (ctype) {
1309        case MEM_CGROUP_CHARGE_TYPE_MAPPED:
1310                if (page_mapped(page))
1311                        goto unlock_out;
1312                break;
1313        case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
1314                if (!PageAnon(page)) {  /* Shared memory */
1315                        if (page->mapping && !page_is_file_cache(page))
1316                                goto unlock_out;
1317                } else if (page_mapped(page)) /* Anon */
1318                                goto unlock_out;
1319                break;
1320        default:
1321                break;
1322        }
1323
1324        res_counter_uncharge(&mem->res, PAGE_SIZE);
1325        if (do_swap_account && (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
1326                res_counter_uncharge(&mem->memsw, PAGE_SIZE);
1327
1328        mem_cgroup_charge_statistics(mem, pc, false);
1329        ClearPageCgroupUsed(pc);
1330        /*
1331         * pc->mem_cgroup is not cleared here. It will be accessed when it's
1332         * freed from LRU. This is safe because uncharged page is expected not
1333         * to be reused (freed soon). Exception is SwapCache, it's handled by
1334         * special functions.
1335         */
1336
1337        mz = page_cgroup_zoneinfo(pc);
1338        unlock_page_cgroup(pc);
1339
1340        /* at swapout, this memcg will be accessed to record to swap */
1341        if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
1342                css_put(&mem->css);
1343
1344        return mem;
1345
1346unlock_out:
1347        unlock_page_cgroup(pc);
1348        return NULL;
1349}
1350
1351void mem_cgroup_uncharge_page(struct page *page)
1352{
1353        /* early check. */
1354        if (page_mapped(page))
1355                return;
1356        if (page->mapping && !PageAnon(page))
1357                return;
1358        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
1359}
1360
1361void mem_cgroup_uncharge_cache_page(struct page *page)
1362{
1363        VM_BUG_ON(page_mapped(page));
1364        VM_BUG_ON(page->mapping);
1365        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
1366}
1367
1368/*
1369 * called from __delete_from_swap_cache() and drop "page" account.
1370 * memcg information is recorded to swap_cgroup of "ent"
1371 */
1372void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
1373{
1374        struct mem_cgroup *memcg;
1375
1376        memcg = __mem_cgroup_uncharge_common(page,
1377                                        MEM_CGROUP_CHARGE_TYPE_SWAPOUT);
1378        /* record memcg information */
1379        if (do_swap_account && memcg) {
1380                swap_cgroup_record(ent, memcg);
1381                mem_cgroup_get(memcg);
1382        }
1383        if (memcg)
1384                css_put(&memcg->css);
1385}
1386
1387#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
1388/*
1389 * called from swap_entry_free(). remove record in swap_cgroup and
1390 * uncharge "memsw" account.
1391 */
1392void mem_cgroup_uncharge_swap(swp_entry_t ent)
1393{
1394        struct mem_cgroup *memcg;
1395
1396        if (!do_swap_account)
1397                return;
1398
1399        memcg = swap_cgroup_record(ent, NULL);
1400        if (memcg) {
1401                res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
1402                mem_cgroup_put(memcg);
1403        }
1404}
1405#endif
1406
1407/*
1408 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
1409 * page belongs to.
1410 */
1411int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
1412{
1413        struct page_cgroup *pc;
1414        struct mem_cgroup *mem = NULL;
1415        int ret = 0;
1416
1417        if (mem_cgroup_disabled())
1418                return 0;
1419
1420        pc = lookup_page_cgroup(page);
1421        lock_page_cgroup(pc);
1422        if (PageCgroupUsed(pc)) {
1423                mem = pc->mem_cgroup;
1424                css_get(&mem->css);
1425        }
1426        unlock_page_cgroup(pc);
1427
1428        if (mem) {
1429                ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
1430                css_put(&mem->css);
1431        }
1432        *ptr = mem;
1433        return ret;
1434}
1435
1436/* remove redundant charge if migration failed*/
1437void mem_cgroup_end_migration(struct mem_cgroup *mem,
1438                struct page *oldpage, struct page *newpage)
1439{
1440        struct page *target, *unused;
1441        struct page_cgroup *pc;
1442        enum charge_type ctype;
1443
1444        if (!mem)
1445                return;
1446
1447        /* at migration success, oldpage->mapping is NULL. */
1448        if (oldpage->mapping) {
1449                target = oldpage;
1450                unused = NULL;
1451        } else {
1452                target = newpage;
1453                unused = oldpage;
1454        }
1455
1456        if (PageAnon(target))
1457                ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
1458        else if (page_is_file_cache(target))
1459                ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
1460        else
1461                ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
1462
1463        /* unused page is not on radix-tree now. */
1464        if (unused)
1465                __mem_cgroup_uncharge_common(unused, ctype);
1466
1467        pc = lookup_page_cgroup(target);
1468        /*
1469         * __mem_cgroup_commit_charge() check PCG_USED bit of page_cgroup.
1470         * So, double-counting is effectively avoided.
1471         */
1472        __mem_cgroup_commit_charge(mem, pc, ctype);
1473
1474        /*
1475         * Both of oldpage and newpage are still under lock_page().
1476         * Then, we don't have to care about race in radix-tree.
1477         * But we have to be careful that this page is unmapped or not.
1478         *
1479         * There is a case for !page_mapped(). At the start of
1480         * migration, oldpage was mapped. But now, it's zapped.
1481         * But we know *target* page is not freed/reused under us.
1482         * mem_cgroup_uncharge_page() does all necessary checks.
1483         */
1484        if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
1485                mem_cgroup_uncharge_page(target);
1486}
1487
1488/*
1489 * A call to try to shrink memory usage under specified resource controller.
1490 * This is typically used for page reclaiming for shmem for reducing side
1491 * effect of page allocation from shmem, which is used by some mem_cgroup.
1492 */
1493int mem_cgroup_shrink_usage(struct page *page,
1494                            struct mm_struct *mm,
1495                            gfp_t gfp_mask)
1496{
1497        struct mem_cgroup *mem = NULL;
1498        int progress = 0;
1499        int retry = MEM_CGROUP_RECLAIM_RETRIES;
1500
1501        if (mem_cgroup_disabled())
1502                return 0;
1503        if (page)
1504                mem = try_get_mem_cgroup_from_swapcache(page);
1505        if (!mem && mm)
1506                mem = try_get_mem_cgroup_from_mm(mm);
1507        if (unlikely(!mem))
1508                return 0;
1509
1510        do {
1511                progress = mem_cgroup_hierarchical_reclaim(mem, gfp_mask, true);
1512                progress += mem_cgroup_check_under_limit(mem);
1513        } while (!progress && --retry);
1514
1515        css_put(&mem->css);
1516        if (!retry)
1517                return -ENOMEM;
1518        return 0;
1519}
1520
1521static DEFINE_MUTEX(set_limit_mutex);
1522
1523static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
1524                                unsigned long long val)
1525{
1526
1527        int retry_count = MEM_CGROUP_RECLAIM_RETRIES;
1528        int progress;
1529        u64 memswlimit;
1530        int ret = 0;
1531
1532        while (retry_count) {
1533                if (signal_pending(current)) {
1534                        ret = -EINTR;
1535                        break;
1536                }
1537                /*
1538                 * Rather than hide all in some function, I do this in
1539                 * open coded manner. You see what this really does.
1540                 * We have to guarantee mem->res.limit < mem->memsw.limit.
1541                 */
1542                mutex_lock(&set_limit_mutex);
1543                memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1544                if (memswlimit < val) {
1545                        ret = -EINVAL;
1546                        mutex_unlock(&set_limit_mutex);
1547                        break;
1548                }
1549                ret = res_counter_set_limit(&memcg->res, val);
1550                mutex_unlock(&set_limit_mutex);
1551
1552                if (!ret)
1553                        break;
1554
1555                progress = mem_cgroup_hierarchical_reclaim(memcg, GFP_KERNEL,
1556                                                           false);
1557                if (!progress)                  retry_count--;
1558        }
1559
1560        return ret;
1561}
1562
1563int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
1564                                unsigned long long val)
1565{
1566        int retry_count = MEM_CGROUP_RECLAIM_RETRIES;
1567        u64 memlimit, oldusage, curusage;
1568        int ret;
1569
1570        if (!do_swap_account)
1571                return -EINVAL;
1572
1573        while (retry_count) {
1574                if (signal_pending(current)) {
1575                        ret = -EINTR;
1576                        break;
1577                }
1578                /*
1579                 * Rather than hide all in some function, I do this in
1580                 * open coded manner. You see what this really does.
1581                 * We have to guarantee mem->res.limit < mem->memsw.limit.
1582                 */
1583                mutex_lock(&set_limit_mutex);
1584                memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
1585                if (memlimit > val) {
1586                        ret = -EINVAL;
1587                        mutex_unlock(&set_limit_mutex);
1588                        break;
1589                }
1590                ret = res_counter_set_limit(&memcg->memsw, val);
1591                mutex_unlock(&set_limit_mutex);
1592
1593                if (!ret)
1594                        break;
1595
1596                oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
1597                mem_cgroup_hierarchical_reclaim(memcg, GFP_KERNEL, true);
1598                curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
1599                if (curusage >= oldusage)
1600                        retry_count--;
1601        }
1602        return ret;
1603}
1604
1605/*
1606 * This routine traverse page_cgroup in given list and drop them all.
1607 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
1608 */
1609static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
1610                                int node, int zid, enum lru_list lru)
1611{
1612        struct zone *zone;
1613        struct mem_cgroup_per_zone *mz;
1614        struct page_cgroup *pc, *busy;
1615        unsigned long flags, loop;
1616        struct list_head *list;
1617        int ret = 0;
1618
1619        zone = &NODE_DATA(node)->node_zones[zid];
1620        mz = mem_cgroup_zoneinfo(mem, node, zid);
1621        list = &mz->lists[lru];
1622
1623        loop = MEM_CGROUP_ZSTAT(mz, lru);
1624        /* give some margin against EBUSY etc...*/
1625        loop += 256;
1626        busy = NULL;
1627        while (loop--) {
1628                ret = 0;
1629                spin_lock_irqsave(&zone->lru_lock, flags);
1630                if (list_empty(list)) {
1631                        spin_unlock_irqrestore(&zone->lru_lock, flags);
1632                        break;
1633                }
1634                pc = list_entry(list->prev, struct page_cgroup, lru);
1635                if (busy == pc) {
1636                        list_move(&pc->lru, list);
1637                        busy = 0;
1638                        spin_unlock_irqrestore(&zone->lru_lock, flags);
1639                        continue;
1640                }
1641                spin_unlock_irqrestore(&zone->lru_lock, flags);
1642
1643                ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
1644                if (ret == -ENOMEM)
1645                        break;
1646
1647                if (ret == -EBUSY || ret == -EINVAL) {
1648                        /* found lock contention or "pc" is obsolete. */
1649                        busy = pc;
1650                        cond_resched();
1651                } else
1652                        busy = NULL;
1653        }
1654
1655        if (!ret && !list_empty(list))
1656                return -EBUSY;
1657        return ret;
1658}
1659
1660/*
1661 * make mem_cgroup's charge to be 0 if there is no task.
1662 * This enables deleting this mem_cgroup.
1663 */
1664static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
1665{
1666        int ret;
1667        int node, zid, shrink;
1668        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
1669        struct cgroup *cgrp = mem->css.cgroup;
1670
1671        css_get(&mem->css);
1672
1673        shrink = 0;
1674        /* should free all ? */
1675        if (free_all)
1676                goto try_to_free;
1677move_account:
1678        while (mem->res.usage > 0) {
1679                ret = -EBUSY;
1680                if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
1681                        goto out;
1682                ret = -EINTR;
1683                if (signal_pending(current))
1684                        goto out;
1685                /* This is for making all *used* pages to be on LRU. */
1686                lru_add_drain_all();
1687                ret = 0;
1688                for_each_node_state(node, N_HIGH_MEMORY) {
1689                        for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
1690                                enum lru_list l;
1691                                for_each_lru(l) {
1692                                        ret = mem_cgroup_force_empty_list(mem,
1693                                                        node, zid, l);
1694                                        if (ret)
1695                                                break;
1696                                }
1697                        }
1698                        if (ret)
1699                                break;
1700                }
1701                /* it seems parent cgroup doesn't have enough mem */
1702                if (ret == -ENOMEM)
1703                        goto try_to_free;
1704                cond_resched();
1705        }
1706        ret = 0;
1707out:
1708        css_put(&mem->css);
1709        return ret;
1710
1711try_to_free:
1712        /* returns EBUSY if there is a task or if we come here twice. */
1713        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
1714                ret = -EBUSY;
1715                goto out;
1716        }
1717        /* we call try-to-free pages for make this cgroup empty */
1718        lru_add_drain_all();
1719        /* try to free all pages in this cgroup */
1720        shrink = 1;
1721        while (nr_retries && mem->res.usage > 0) {
1722                int progress;
1723
1724                if (signal_pending(current)) {
1725                        ret = -EINTR;
1726                        goto out;
1727                }
1728                progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
1729                                                false, get_swappiness(mem));
1730                if (!progress) {
1731                        nr_retries--;
1732                        /* maybe some writeback is necessary */
1733                        congestion_wait(WRITE, HZ/10);
1734                }
1735
1736        }
1737        lru_add_drain();
1738        /* try move_account...there may be some *locked* pages. */
1739        if (mem->res.usage)
1740                goto move_account;
1741        ret = 0;
1742        goto out;
1743}
1744
1745int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
1746{
1747        return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
1748}
1749
1750
1751static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
1752{
1753        return mem_cgroup_from_cont(cont)->use_hierarchy;
1754}
1755
1756static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
1757                                        u64 val)
1758{
1759        int retval = 0;
1760        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
1761        struct cgroup *parent = cont->parent;
1762        struct mem_cgroup *parent_mem = NULL;
1763
1764        if (parent)
1765                parent_mem = mem_cgroup_from_cont(parent);
1766
1767        cgroup_lock();
1768        /*
1769         * If parent's use_hiearchy is set, we can't make any modifications
1770         * in the child subtrees. If it is unset, then the change can
1771         * occur, provided the current cgroup has no children.
1772         *
1773         * For the root cgroup, parent_mem is NULL, we allow value to be
1774         * set if there are no children.
1775         */
1776        if ((!parent_mem || !parent_mem->use_hierarchy) &&
1777                                (val == 1 || val == 0)) {
1778                if (list_empty(&cont->children))
1779                        mem->use_hierarchy = val;
1780                else
1781                        retval = -EBUSY;
1782        } else
1783                retval = -EINVAL;
1784        cgroup_unlock();
1785
1786        return retval;
1787}
1788
1789static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
1790{
1791        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
1792        u64 val = 0;
1793        int type, name;
1794
1795        type = MEMFILE_TYPE(cft->private);
1796        name = MEMFILE_ATTR(cft->private);
1797        switch (type) {
1798        case _MEM:
1799                val = res_counter_read_u64(&mem->res, name);
1800                break;
1801        case _MEMSWAP:
1802                if (do_swap_account)
1803                        val = res_counter_read_u64(&mem->memsw, name);
1804                break;
1805        default:
1806                BUG();
1807                break;
1808        }
1809        return val;
1810}
1811/*
1812 * The user of this function is...
1813 * RES_LIMIT.
1814 */
1815static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
1816                            const char *buffer)
1817{
1818        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
1819        int type, name;
1820        unsigned long long val;
1821        int ret;
1822
1823        type = MEMFILE_TYPE(cft->private);
1824        name = MEMFILE_ATTR(cft->private);
1825        switch (name) {
1826        case RES_LIMIT:
1827                /* This function does all necessary parse...reuse it */
1828                ret = res_counter_memparse_write_strategy(buffer, &val);
1829                if (ret)
1830                        break;
1831                if (type == _MEM)
1832                        ret = mem_cgroup_resize_limit(memcg, val);
1833                else
1834                        ret = mem_cgroup_resize_memsw_limit(memcg, val);
1835                break;
1836        default:
1837                ret = -EINVAL; /* should be BUG() ? */
1838                break;
1839        }
1840        return ret;
1841}
1842
1843static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
1844                unsigned long long *mem_limit, unsigned long long *memsw_limit)
1845{
1846        struct cgroup *cgroup;
1847        unsigned long long min_limit, min_memsw_limit, tmp;
1848
1849        min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
1850        min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1851        cgroup = memcg->css.cgroup;
1852        if (!memcg->use_hierarchy)
1853                goto out;
1854
1855        while (cgroup->parent) {
1856                cgroup = cgroup->parent;
1857                memcg = mem_cgroup_from_cont(cgroup);
1858                if (!memcg->use_hierarchy)
1859                        break;
1860                tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
1861                min_limit = min(min_limit, tmp);
1862                tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
1863                min_memsw_limit = min(min_memsw_limit, tmp);
1864        }
1865out:
1866        *mem_limit = min_limit;
1867        *memsw_limit = min_memsw_limit;
1868        return;
1869}
1870
1871static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
1872{
1873        struct mem_cgroup *mem;
1874        int type, name;
1875
1876        mem = mem_cgroup_from_cont(cont);
1877        type = MEMFILE_TYPE(event);
1878        name = MEMFILE_ATTR(event);
1879        switch (name) {
1880        case RES_MAX_USAGE:
1881                if (type == _MEM)
1882                        res_counter_reset_max(&mem->res);
1883                else
1884                        res_counter_reset_max(&mem->memsw);
1885                break;
1886        case RES_FAILCNT:
1887                if (type == _MEM)
1888                        res_counter_reset_failcnt(&mem->res);
1889                else
1890                        res_counter_reset_failcnt(&mem->memsw);
1891                break;
1892        }
1893        return 0;
1894}
1895
1896static const struct mem_cgroup_stat_desc {
1897        const char *msg;
1898        u64 unit;
1899} mem_cgroup_stat_desc[] = {
1900        [MEM_CGROUP_STAT_CACHE] = { "cache", PAGE_SIZE, },
1901        [MEM_CGROUP_STAT_RSS] = { "rss", PAGE_SIZE, },
1902        [MEM_CGROUP_STAT_PGPGIN_COUNT] = {"pgpgin", 1, },
1903        [MEM_CGROUP_STAT_PGPGOUT_COUNT] = {"pgpgout", 1, },
1904};
1905
1906static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
1907                                 struct cgroup_map_cb *cb)
1908{
1909        struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
1910        struct mem_cgroup_stat *stat = &mem_cont->stat;
1911        int i;
1912
1913        for (i = 0; i < ARRAY_SIZE(stat->cpustat[0].count); i++) {
1914                s64 val;
1915
1916                val = mem_cgroup_read_stat(stat, i);
1917                val *= mem_cgroup_stat_desc[i].unit;
1918                cb->fill(cb, mem_cgroup_stat_desc[i].msg, val);
1919        }
1920        /* showing # of active pages */
1921        {
1922                unsigned long active_anon, inactive_anon;
1923                unsigned long active_file, inactive_file;
1924                unsigned long unevictable;
1925
1926                inactive_anon = mem_cgroup_get_all_zonestat(mem_cont,
1927                                                LRU_INACTIVE_ANON);
1928                active_anon = mem_cgroup_get_all_zonestat(mem_cont,
1929                                                LRU_ACTIVE_ANON);
1930                inactive_file = mem_cgroup_get_all_zonestat(mem_cont,
1931                                                LRU_INACTIVE_FILE);
1932                active_file = mem_cgroup_get_all_zonestat(mem_cont,
1933                                                LRU_ACTIVE_FILE);
1934                unevictable = mem_cgroup_get_all_zonestat(mem_cont,
1935                                                        LRU_UNEVICTABLE);
1936
1937                cb->fill(cb, "active_anon", (active_anon) * PAGE_SIZE);
1938                cb->fill(cb, "inactive_anon", (inactive_anon) * PAGE_SIZE);
1939                cb->fill(cb, "active_file", (active_file) * PAGE_SIZE);
1940                cb->fill(cb, "inactive_file", (inactive_file) * PAGE_SIZE);
1941                cb->fill(cb, "unevictable", unevictable * PAGE_SIZE);
1942
1943        }
1944        {
1945                unsigned long long limit, memsw_limit;
1946                memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
1947                cb->fill(cb, "hierarchical_memory_limit", limit);
1948                if (do_swap_account)
1949                        cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
1950        }
1951
1952#ifdef CONFIG_DEBUG_VM
1953        cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
1954
1955        {
1956                int nid, zid;
1957                struct mem_cgroup_per_zone *mz;
1958                unsigned long recent_rotated[2] = {0, 0};
1959                unsigned long recent_scanned[2] = {0, 0};
1960
1961                for_each_online_node(nid)
1962                        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1963                                mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
1964
1965                                recent_rotated[0] +=
1966                                        mz->reclaim_stat.recent_rotated[0];
1967                                recent_rotated[1] +=
1968                                        mz->reclaim_stat.recent_rotated[1];
1969                                recent_scanned[0] +=
1970                                        mz->reclaim_stat.recent_scanned[0];
1971                                recent_scanned[1] +=
1972                                        mz->reclaim_stat.recent_scanned[1];
1973                        }
1974                cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
1975                cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
1976                cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
1977                cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
1978        }
1979#endif
1980
1981        return 0;
1982}
1983
1984static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
1985{
1986        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
1987
1988        return get_swappiness(memcg);
1989}
1990
1991static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
1992                                       u64 val)
1993{
1994        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
1995        struct mem_cgroup *parent;
1996
1997        if (val > 100)
1998                return -EINVAL;
1999
2000        if (cgrp->parent == NULL)
2001                return -EINVAL;
2002
2003        parent = mem_cgroup_from_cont(cgrp->parent);
2004
2005        cgroup_lock();
2006
2007        /* If under hierarchy, only empty-root can set this value */
2008        if ((parent->use_hierarchy) ||
2009            (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
2010                cgroup_unlock();
2011                return -EINVAL;
2012        }
2013
2014        spin_lock(&memcg->reclaim_param_lock);
2015        memcg->swappiness = val;
2016        spin_unlock(&memcg->reclaim_param_lock);
2017
2018        cgroup_unlock();
2019
2020        return 0;
2021}
2022
2023
2024static struct cftype mem_cgroup_files[] = {
2025        {
2026                .name = "usage_in_bytes",
2027                .private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
2028                .read_u64 = mem_cgroup_read,
2029        },
2030        {
2031                .name = "max_usage_in_bytes",
2032                .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
2033                .trigger = mem_cgroup_reset,
2034                .read_u64 = mem_cgroup_read,
2035        },
2036        {
2037                .name = "limit_in_bytes",
2038                .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
2039                .write_string = mem_cgroup_write,
2040                .read_u64 = mem_cgroup_read,
2041        },
2042        {
2043                .name = "failcnt",
2044                .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
2045                .trigger = mem_cgroup_reset,
2046                .read_u64 = mem_cgroup_read,
2047        },
2048        {
2049                .name = "stat",
2050                .read_map = mem_control_stat_show,
2051        },
2052        {
2053                .name = "force_empty",
2054                .trigger = mem_cgroup_force_empty_write,
2055        },
2056        {
2057                .name = "use_hierarchy",
2058                .write_u64 = mem_cgroup_hierarchy_write,
2059                .read_u64 = mem_cgroup_hierarchy_read,
2060        },
2061        {
2062                .name = "swappiness",
2063                .read_u64 = mem_cgroup_swappiness_read,
2064                .write_u64 = mem_cgroup_swappiness_write,
2065        },
2066};
2067
2068#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2069static struct cftype memsw_cgroup_files[] = {
2070        {
2071                .name = "memsw.usage_in_bytes",
2072                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
2073                .read_u64 = mem_cgroup_read,
2074        },
2075        {
2076                .name = "memsw.max_usage_in_bytes",
2077                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
2078                .trigger = mem_cgroup_reset,
2079                .read_u64 = mem_cgroup_read,
2080        },
2081        {
2082                .name = "memsw.limit_in_bytes",
2083                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
2084                .write_string = mem_cgroup_write,
2085                .read_u64 = mem_cgroup_read,
2086        },
2087        {
2088                .name = "memsw.failcnt",
2089                .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
2090                .trigger = mem_cgroup_reset,
2091                .read_u64 = mem_cgroup_read,
2092        },
2093};
2094
2095static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
2096{
2097        if (!do_swap_account)
2098                return 0;
2099        return cgroup_add_files(cont, ss, memsw_cgroup_files,
2100                                ARRAY_SIZE(memsw_cgroup_files));
2101};
2102#else
2103static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
2104{
2105        return 0;
2106}
2107#endif
2108
2109static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
2110{
2111        struct mem_cgroup_per_node *pn;
2112        struct mem_cgroup_per_zone *mz;
2113        enum lru_list l;
2114        int zone, tmp = node;
2115        /*
2116         * This routine is called against possible nodes.
2117         * But it's BUG to call kmalloc() against offline node.
2118         *
2119         * TODO: this routine can waste much memory for nodes which will
2120         *       never be onlined. It's better to use memory hotplug callback
2121         *       function.
2122         */
2123        if (!node_state(node, N_NORMAL_MEMORY))
2124                tmp = -1;
2125        pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
2126        if (!pn)
2127                return 1;
2128
2129        mem->info.nodeinfo[node] = pn;
2130        memset(pn, 0, sizeof(*pn));
2131
2132        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
2133                mz = &pn->zoneinfo[zone];
2134                for_each_lru(l)
2135                        INIT_LIST_HEAD(&mz->lists[l]);
2136        }
2137        return 0;
2138}
2139
2140static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
2141{
2142        kfree(mem->info.nodeinfo[node]);
2143}
2144
2145static int mem_cgroup_size(void)
2146{
2147        int cpustat_size = nr_cpu_ids * sizeof(struct mem_cgroup_stat_cpu);
2148        return sizeof(struct mem_cgroup) + cpustat_size;
2149}
2150
2151static struct mem_cgroup *mem_cgroup_alloc(void)
2152{
2153        struct mem_cgroup *mem;
2154        int size = mem_cgroup_size();
2155
2156        if (size < PAGE_SIZE)
2157                mem = kmalloc(size, GFP_KERNEL);
2158        else
2159                mem = vmalloc(size);
2160
2161        if (mem)
2162                memset(mem, 0, size);
2163        return mem;
2164}
2165
2166/*
2167 * At destroying mem_cgroup, references from swap_cgroup can remain.
2168 * (scanning all at force_empty is too costly...)
2169 *
2170 * Instead of clearing all references at force_empty, we remember
2171 * the number of reference from swap_cgroup and free mem_cgroup when
2172 * it goes down to 0.
2173 *
2174 * Removal of cgroup itself succeeds regardless of refs from swap.
2175 */
2176
2177static void __mem_cgroup_free(struct mem_cgroup *mem)
2178{
2179        int node;
2180
2181        for_each_node_state(node, N_POSSIBLE)
2182                free_mem_cgroup_per_zone_info(mem, node);
2183
2184        if (mem_cgroup_size() < PAGE_SIZE)
2185                kfree(mem);
2186        else
2187                vfree(mem);
2188}
2189
2190static void mem_cgroup_get(struct mem_cgroup *mem)
2191{
2192        atomic_inc(&mem->refcnt);
2193}
2194
2195static void mem_cgroup_put(struct mem_cgroup *mem)
2196{
2197        if (atomic_dec_and_test(&mem->refcnt)) {
2198                struct mem_cgroup *parent = parent_mem_cgroup(mem);
2199                __mem_cgroup_free(mem);
2200                if (parent)
2201                        mem_cgroup_put(parent);
2202        }
2203}
2204
2205/*
2206 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
2207 */
2208static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem)
2209{
2210        if (!mem->res.parent)
2211                return NULL;
2212        return mem_cgroup_from_res_counter(mem->res.parent, res);
2213}
2214
2215#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2216static void __init enable_swap_cgroup(void)
2217{
2218        if (!mem_cgroup_disabled() && really_do_swap_account)
2219                do_swap_account = 1;
2220}
2221#else
2222static void __init enable_swap_cgroup(void)
2223{
2224}
2225#endif
2226
2227static struct cgroup_subsys_state * __ref
2228mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
2229{
2230        struct mem_cgroup *mem, *parent;
2231        int node;
2232
2233        mem = mem_cgroup_alloc();
2234        if (!mem)
2235                return ERR_PTR(-ENOMEM);
2236
2237        for_each_node_state(node, N_POSSIBLE)
2238                if (alloc_mem_cgroup_per_zone_info(mem, node))
2239                        goto free_out;
2240        /* root ? */
2241        if (cont->parent == NULL) {
2242                enable_swap_cgroup();
2243                parent = NULL;
2244        } else {
2245                parent = mem_cgroup_from_cont(cont->parent);
2246                mem->use_hierarchy = parent->use_hierarchy;
2247        }
2248
2249        if (parent && parent->use_hierarchy) {
2250                res_counter_init(&mem->res, &parent->res);
2251                res_counter_init(&mem->memsw, &parent->memsw);
2252                /*
2253                 * We increment refcnt of the parent to ensure that we can
2254                 * safely access it on res_counter_charge/uncharge.
2255                 * This refcnt will be decremented when freeing this
2256                 * mem_cgroup(see mem_cgroup_put).
2257                 */
2258                mem_cgroup_get(parent);
2259        } else {
2260                res_counter_init(&mem->res, NULL);
2261                res_counter_init(&mem->memsw, NULL);
2262        }
2263        mem->last_scanned_child = NULL;
2264        spin_lock_init(&mem->reclaim_param_lock);
2265
2266        if (parent)
2267                mem->swappiness = get_swappiness(parent);
2268        atomic_set(&mem->refcnt, 1);
2269        return &mem->css;
2270free_out:
2271        __mem_cgroup_free(mem);
2272        return ERR_PTR(-ENOMEM);
2273}
2274
2275static void mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
2276                                        struct cgroup *cont)
2277{
2278        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
2279        mem_cgroup_force_empty(mem, false);
2280}
2281
2282static void mem_cgroup_destroy(struct cgroup_subsys *ss,
2283                                struct cgroup *cont)
2284{
2285        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
2286        struct mem_cgroup *last_scanned_child = mem->last_scanned_child;
2287
2288        if (last_scanned_child) {
2289                VM_BUG_ON(!mem_cgroup_is_obsolete(last_scanned_child));
2290                mem_cgroup_put(last_scanned_child);
2291        }
2292        mem_cgroup_put(mem);
2293}
2294
2295static int mem_cgroup_populate(struct cgroup_subsys *ss,
2296                                struct cgroup *cont)
2297{
2298        int ret;
2299
2300        ret = cgroup_add_files(cont, ss, mem_cgroup_files,
2301                                ARRAY_SIZE(mem_cgroup_files));
2302
2303        if (!ret)
2304                ret = register_memsw_files(cont, ss);
2305        return ret;
2306}
2307
2308static void mem_cgroup_move_task(struct cgroup_subsys *ss,
2309                                struct cgroup *cont,
2310                                struct cgroup *old_cont,
2311                                struct task_struct *p)
2312{
2313        mutex_lock(&memcg_tasklist);
2314        /*
2315         * FIXME: It's better to move charges of this process from old
2316         * memcg to new memcg. But it's just on TODO-List now.
2317         */
2318        mutex_unlock(&memcg_tasklist);
2319}
2320
2321struct cgroup_subsys mem_cgroup_subsys = {
2322        .name = "memory",
2323        .subsys_id = mem_cgroup_subsys_id,
2324        .create = mem_cgroup_create,
2325        .pre_destroy = mem_cgroup_pre_destroy,
2326        .destroy = mem_cgroup_destroy,
2327        .populate = mem_cgroup_populate,
2328        .attach = mem_cgroup_move_task,
2329        .early_init = 0,
2330};
2331
2332#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
2333
2334static int __init disable_swap_account(char *s)
2335{
2336        really_do_swap_account = 0;
2337        return 1;
2338}
2339__setup("noswapaccount", disable_swap_account);
2340#endif
2341