1 /* memcontrol.c - Memory Controller 2 * 3 * Copyright IBM Corporation, 2007 4 * Author Balbir Singh <balbir@linux.vnet.ibm.com> 5 * 6 * Copyright 2007 OpenVZ SWsoft Inc 7 * Author: Pavel Emelianov <xemul@openvz.org> 8 * 9 * Memory thresholds 10 * Copyright (C) 2009 Nokia Corporation 11 * Author: Kirill A. Shutemov 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License as published by 15 * the Free Software Foundation; either version 2 of the License, or 16 * (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 */ 23 24 #include <linux/res_counter.h> 25 #include <linux/memcontrol.h> 26 #include <linux/cgroup.h> 27 #include <linux/mm.h> 28 #include <linux/hugetlb.h> 29 #include <linux/pagemap.h> 30 #include <linux/smp.h> 31 #include <linux/page-flags.h> 32 #include <linux/backing-dev.h> 33 #include <linux/bit_spinlock.h> 34 #include <linux/rcupdate.h> 35 #include <linux/limits.h> 36 #include <linux/mutex.h> 37 #include <linux/rbtree.h> 38 #include <linux/slab.h> 39 #include <linux/swap.h> 40 #include <linux/swapops.h> 41 #include <linux/spinlock.h> 42 #include <linux/eventfd.h> 43 #include <linux/sort.h> 44 #include <linux/fs.h> 45 #include <linux/seq_file.h> 46 #include <linux/vmalloc.h> 47 #include <linux/mm_inline.h> 48 #include <linux/page_cgroup.h> 49 #include <linux/cpu.h> 50 #include "internal.h" 51 52 #include <asm/uaccess.h> 53 54 struct cgroup_subsys mem_cgroup_subsys __read_mostly; 55 #define MEM_CGROUP_RECLAIM_RETRIES 5 56 struct mem_cgroup *root_mem_cgroup __read_mostly; 57 58 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP 59 /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */ 60 int do_swap_account __read_mostly; 61 static int really_do_swap_account __initdata = 1; /* for remember boot option*/ 62 #else 63 #define do_swap_account (0) 64 #endif 65 66 /* 67 * Per memcg event counter is incremented at every pagein/pageout. This counter 68 * is used for trigger some periodic events. This is straightforward and better 69 * than using jiffies etc. to handle periodic memcg event. 70 * 71 * These values will be used as !((event) & ((1 <<(thresh)) - 1)) 72 */ 73 #define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */ 74 #define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */ 75 76 /* 77 * Statistics for memory cgroup. 78 */ 79 enum mem_cgroup_stat_index { 80 /* 81 * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss. 82 */ 83 MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */ 84 MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */ 85 MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */ 86 MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */ 87 MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */ 88 MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */ 89 MEM_CGROUP_EVENTS, /* incremented at every pagein/pageout */ 90 91 MEM_CGROUP_STAT_NSTATS, 92 }; 93 94 struct mem_cgroup_stat_cpu { 95 s64 count[MEM_CGROUP_STAT_NSTATS]; 96 }; 97 98 /* 99 * per-zone information in memory controller. 100 */ 101 struct 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 struct rb_node tree_node; /* RB tree node */ 110 unsigned long long usage_in_excess;/* Set to the value by which */ 111 /* the soft limit is exceeded*/ 112 bool on_tree; 113 struct mem_cgroup *mem; /* Back pointer, we cannot */ 114 /* use container_of */ 115 }; 116 /* Macro for accessing counter */ 117 #define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)]) 118 119 struct mem_cgroup_per_node { 120 struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES]; 121 }; 122 123 struct mem_cgroup_lru_info { 124 struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES]; 125 }; 126 127 /* 128 * Cgroups above their limits are maintained in a RB-Tree, independent of 129 * their hierarchy representation 130 */ 131 132 struct mem_cgroup_tree_per_zone { 133 struct rb_root rb_root; 134 spinlock_t lock; 135 }; 136 137 struct mem_cgroup_tree_per_node { 138 struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES]; 139 }; 140 141 struct mem_cgroup_tree { 142 struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES]; 143 }; 144 145 static struct mem_cgroup_tree soft_limit_tree __read_mostly; 146 147 struct mem_cgroup_threshold { 148 struct eventfd_ctx *eventfd; 149 u64 threshold; 150 }; 151 152 struct mem_cgroup_threshold_ary { 153 /* An array index points to threshold just below usage. */ 154 atomic_t current_threshold; 155 /* Size of entries[] */ 156 unsigned int size; 157 /* Array of thresholds */ 158 struct mem_cgroup_threshold entries[0]; 159 }; 160 161 static void mem_cgroup_threshold(struct mem_cgroup *mem); 162 163 /* 164 * The memory controller data structure. The memory controller controls both 165 * page cache and RSS per cgroup. We would eventually like to provide 166 * statistics based on the statistics developed by Rik Van Riel for clock-pro, 167 * to help the administrator determine what knobs to tune. 168 * 169 * TODO: Add a water mark for the memory controller. Reclaim will begin when 170 * we hit the water mark. May be even add a low water mark, such that 171 * no reclaim occurs from a cgroup at it's low water mark, this is 172 * a feature that will be implemented much later in the future. 173 */ 174 struct mem_cgroup { 175 struct cgroup_subsys_state css; 176 /* 177 * the counter to account for memory usage 178 */ 179 struct res_counter res; 180 /* 181 * the counter to account for mem+swap usage. 182 */ 183 struct res_counter memsw; 184 /* 185 * Per cgroup active and inactive list, similar to the 186 * per zone LRU lists. 187 */ 188 struct mem_cgroup_lru_info info; 189 190 /* 191 protect against reclaim related member. 192 */ 193 spinlock_t reclaim_param_lock; 194 195 int prev_priority; /* for recording reclaim priority */ 196 197 /* 198 * While reclaiming in a hierarchy, we cache the last child we 199 * reclaimed from. 200 */ 201 int last_scanned_child; 202 /* 203 * Should the accounting and control be hierarchical, per subtree? 204 */ 205 bool use_hierarchy; 206 atomic_t oom_lock; 207 atomic_t refcnt; 208 209 unsigned int swappiness; 210 211 /* set when res.limit == memsw.limit */ 212 bool memsw_is_minimum; 213 214 /* protect arrays of thresholds */ 215 struct mutex thresholds_lock; 216 217 /* thresholds for memory usage. RCU-protected */ 218 struct mem_cgroup_threshold_ary *thresholds; 219 220 /* thresholds for mem+swap usage. RCU-protected */ 221 struct mem_cgroup_threshold_ary *memsw_thresholds; 222 223 /* 224 * Should we move charges of a task when a task is moved into this 225 * mem_cgroup ? And what type of charges should we move ? 226 */ 227 unsigned long move_charge_at_immigrate; 228 229 /* 230 * percpu counter. 231 */ 232 struct mem_cgroup_stat_cpu *stat; 233 }; 234 235 /* Stuffs for move charges at task migration. */ 236 /* 237 * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a 238 * left-shifted bitmap of these types. 239 */ 240 enum move_type { 241 MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */ 242 NR_MOVE_TYPE, 243 }; 244 245 /* "mc" and its members are protected by cgroup_mutex */ 246 static struct move_charge_struct { 247 struct mem_cgroup *from; 248 struct mem_cgroup *to; 249 unsigned long precharge; 250 unsigned long moved_charge; 251 unsigned long moved_swap; 252 struct task_struct *moving_task; /* a task moving charges */ 253 wait_queue_head_t waitq; /* a waitq for other context */ 254 } mc = { 255 .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), 256 }; 257 258 /* 259 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft 260 * limit reclaim to prevent infinite loops, if they ever occur. 261 */ 262 #define MEM_CGROUP_MAX_RECLAIM_LOOPS (100) 263 #define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2) 264 265 enum charge_type { 266 MEM_CGROUP_CHARGE_TYPE_CACHE = 0, 267 MEM_CGROUP_CHARGE_TYPE_MAPPED, 268 MEM_CGROUP_CHARGE_TYPE_SHMEM, /* used by page migration of shmem */ 269 MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */ 270 MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */ 271 MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */ 272 NR_CHARGE_TYPE, 273 }; 274 275 /* only for here (for easy reading.) */ 276 #define PCGF_CACHE (1UL << PCG_CACHE) 277 #define PCGF_USED (1UL << PCG_USED) 278 #define PCGF_LOCK (1UL << PCG_LOCK) 279 /* Not used, but added here for completeness */ 280 #define PCGF_ACCT (1UL << PCG_ACCT) 281 282 /* for encoding cft->private value on file */ 283 #define _MEM (0) 284 #define _MEMSWAP (1) 285 #define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val)) 286 #define MEMFILE_TYPE(val) (((val) >> 16) & 0xffff) 287 #define MEMFILE_ATTR(val) ((val) & 0xffff) 288 289 /* 290 * Reclaim flags for mem_cgroup_hierarchical_reclaim 291 */ 292 #define MEM_CGROUP_RECLAIM_NOSWAP_BIT 0x0 293 #define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT) 294 #define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1 295 #define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT) 296 #define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2 297 #define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT) 298 299 static void mem_cgroup_get(struct mem_cgroup *mem); 300 static void mem_cgroup_put(struct mem_cgroup *mem); 301 static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem); 302 static void drain_all_stock_async(void); 303 304 static struct mem_cgroup_per_zone * 305 mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid) 306 { 307 return &mem->info.nodeinfo[nid]->zoneinfo[zid]; 308 } 309 310 struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem) 311 { 312 return &mem->css; 313 } 314 315 static struct mem_cgroup_per_zone * 316 page_cgroup_zoneinfo(struct page_cgroup *pc) 317 { 318 struct mem_cgroup *mem = pc->mem_cgroup; 319 int nid = page_cgroup_nid(pc); 320 int zid = page_cgroup_zid(pc); 321 322 if (!mem) 323 return NULL; 324 325 return mem_cgroup_zoneinfo(mem, nid, zid); 326 } 327 328 static struct mem_cgroup_tree_per_zone * 329 soft_limit_tree_node_zone(int nid, int zid) 330 { 331 return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid]; 332 } 333 334 static struct mem_cgroup_tree_per_zone * 335 soft_limit_tree_from_page(struct page *page) 336 { 337 int nid = page_to_nid(page); 338 int zid = page_zonenum(page); 339 340 return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid]; 341 } 342 343 static void 344 __mem_cgroup_insert_exceeded(struct mem_cgroup *mem, 345 struct mem_cgroup_per_zone *mz, 346 struct mem_cgroup_tree_per_zone *mctz, 347 unsigned long long new_usage_in_excess) 348 { 349 struct rb_node **p = &mctz->rb_root.rb_node; 350 struct rb_node *parent = NULL; 351 struct mem_cgroup_per_zone *mz_node; 352 353 if (mz->on_tree) 354 return; 355 356 mz->usage_in_excess = new_usage_in_excess; 357 if (!mz->usage_in_excess) 358 return; 359 while (*p) { 360 parent = *p; 361 mz_node = rb_entry(parent, struct mem_cgroup_per_zone, 362 tree_node); 363 if (mz->usage_in_excess < mz_node->usage_in_excess) 364 p = &(*p)->rb_left; 365 /* 366 * We can't avoid mem cgroups that are over their soft 367 * limit by the same amount 368 */ 369 else if (mz->usage_in_excess >= mz_node->usage_in_excess) 370 p = &(*p)->rb_right; 371 } 372 rb_link_node(&mz->tree_node, parent, p); 373 rb_insert_color(&mz->tree_node, &mctz->rb_root); 374 mz->on_tree = true; 375 } 376 377 static void 378 __mem_cgroup_remove_exceeded(struct mem_cgroup *mem, 379 struct mem_cgroup_per_zone *mz, 380 struct mem_cgroup_tree_per_zone *mctz) 381 { 382 if (!mz->on_tree) 383 return; 384 rb_erase(&mz->tree_node, &mctz->rb_root); 385 mz->on_tree = false; 386 } 387 388 static void 389 mem_cgroup_remove_exceeded(struct mem_cgroup *mem, 390 struct mem_cgroup_per_zone *mz, 391 struct mem_cgroup_tree_per_zone *mctz) 392 { 393 spin_lock(&mctz->lock); 394 __mem_cgroup_remove_exceeded(mem, mz, mctz); 395 spin_unlock(&mctz->lock); 396 } 397 398 399 static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page) 400 { 401 unsigned long long excess; 402 struct mem_cgroup_per_zone *mz; 403 struct mem_cgroup_tree_per_zone *mctz; 404 int nid = page_to_nid(page); 405 int zid = page_zonenum(page); 406 mctz = soft_limit_tree_from_page(page); 407 408 /* 409 * Necessary to update all ancestors when hierarchy is used. 410 * because their event counter is not touched. 411 */ 412 for (; mem; mem = parent_mem_cgroup(mem)) { 413 mz = mem_cgroup_zoneinfo(mem, nid, zid); 414 excess = res_counter_soft_limit_excess(&mem->res); 415 /* 416 * We have to update the tree if mz is on RB-tree or 417 * mem is over its softlimit. 418 */ 419 if (excess || mz->on_tree) { 420 spin_lock(&mctz->lock); 421 /* if on-tree, remove it */ 422 if (mz->on_tree) 423 __mem_cgroup_remove_exceeded(mem, mz, mctz); 424 /* 425 * Insert again. mz->usage_in_excess will be updated. 426 * If excess is 0, no tree ops. 427 */ 428 __mem_cgroup_insert_exceeded(mem, mz, mctz, excess); 429 spin_unlock(&mctz->lock); 430 } 431 } 432 } 433 434 static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem) 435 { 436 int node, zone; 437 struct mem_cgroup_per_zone *mz; 438 struct mem_cgroup_tree_per_zone *mctz; 439 440 for_each_node_state(node, N_POSSIBLE) { 441 for (zone = 0; zone < MAX_NR_ZONES; zone++) { 442 mz = mem_cgroup_zoneinfo(mem, node, zone); 443 mctz = soft_limit_tree_node_zone(node, zone); 444 mem_cgroup_remove_exceeded(mem, mz, mctz); 445 } 446 } 447 } 448 449 static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem) 450 { 451 return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT; 452 } 453 454 static struct mem_cgroup_per_zone * 455 __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz) 456 { 457 struct rb_node *rightmost = NULL; 458 struct mem_cgroup_per_zone *mz; 459 460 retry: 461 mz = NULL; 462 rightmost = rb_last(&mctz->rb_root); 463 if (!rightmost) 464 goto done; /* Nothing to reclaim from */ 465 466 mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node); 467 /* 468 * Remove the node now but someone else can add it back, 469 * we will to add it back at the end of reclaim to its correct 470 * position in the tree. 471 */ 472 __mem_cgroup_remove_exceeded(mz->mem, mz, mctz); 473 if (!res_counter_soft_limit_excess(&mz->mem->res) || 474 !css_tryget(&mz->mem->css)) 475 goto retry; 476 done: 477 return mz; 478 } 479 480 static struct mem_cgroup_per_zone * 481 mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz) 482 { 483 struct mem_cgroup_per_zone *mz; 484 485 spin_lock(&mctz->lock); 486 mz = __mem_cgroup_largest_soft_limit_node(mctz); 487 spin_unlock(&mctz->lock); 488 return mz; 489 } 490 491 static s64 mem_cgroup_read_stat(struct mem_cgroup *mem, 492 enum mem_cgroup_stat_index idx) 493 { 494 int cpu; 495 s64 val = 0; 496 497 for_each_possible_cpu(cpu) 498 val += per_cpu(mem->stat->count[idx], cpu); 499 return val; 500 } 501 502 static s64 mem_cgroup_local_usage(struct mem_cgroup *mem) 503 { 504 s64 ret; 505 506 ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS); 507 ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE); 508 return ret; 509 } 510 511 static void mem_cgroup_swap_statistics(struct mem_cgroup *mem, 512 bool charge) 513 { 514 int val = (charge) ? 1 : -1; 515 this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_SWAPOUT], val); 516 } 517 518 static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, 519 struct page_cgroup *pc, 520 bool charge) 521 { 522 int val = (charge) ? 1 : -1; 523 524 preempt_disable(); 525 526 if (PageCgroupCache(pc)) 527 __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_CACHE], val); 528 else 529 __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_RSS], val); 530 531 if (charge) 532 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]); 533 else 534 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]); 535 __this_cpu_inc(mem->stat->count[MEM_CGROUP_EVENTS]); 536 537 preempt_enable(); 538 } 539 540 static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem, 541 enum lru_list idx) 542 { 543 int nid, zid; 544 struct mem_cgroup_per_zone *mz; 545 u64 total = 0; 546 547 for_each_online_node(nid) 548 for (zid = 0; zid < MAX_NR_ZONES; zid++) { 549 mz = mem_cgroup_zoneinfo(mem, nid, zid); 550 total += MEM_CGROUP_ZSTAT(mz, idx); 551 } 552 return total; 553 } 554 555 static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift) 556 { 557 s64 val; 558 559 val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]); 560 561 return !(val & ((1 << event_mask_shift) - 1)); 562 } 563 564 /* 565 * Check events in order. 566 * 567 */ 568 static void memcg_check_events(struct mem_cgroup *mem, struct page *page) 569 { 570 /* threshold event is triggered in finer grain than soft limit */ 571 if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) { 572 mem_cgroup_threshold(mem); 573 if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH))) 574 mem_cgroup_update_tree(mem, page); 575 } 576 } 577 578 static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont) 579 { 580 return container_of(cgroup_subsys_state(cont, 581 mem_cgroup_subsys_id), struct mem_cgroup, 582 css); 583 } 584 585 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) 586 { 587 /* 588 * mm_update_next_owner() may clear mm->owner to NULL 589 * if it races with swapoff, page migration, etc. 590 * So this can be called with p == NULL. 591 */ 592 if (unlikely(!p)) 593 return NULL; 594 595 return container_of(task_subsys_state(p, mem_cgroup_subsys_id), 596 struct mem_cgroup, css); 597 } 598 599 static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) 600 { 601 struct mem_cgroup *mem = NULL; 602 603 if (!mm) 604 return NULL; 605 /* 606 * Because we have no locks, mm->owner's may be being moved to other 607 * cgroup. We use css_tryget() here even if this looks 608 * pessimistic (rather than adding locks here). 609 */ 610 rcu_read_lock(); 611 do { 612 mem = mem_cgroup_from_task(rcu_dereference(mm->owner)); 613 if (unlikely(!mem)) 614 break; 615 } while (!css_tryget(&mem->css)); 616 rcu_read_unlock(); 617 return mem; 618 } 619 620 /* 621 * Call callback function against all cgroup under hierarchy tree. 622 */ 623 static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data, 624 int (*func)(struct mem_cgroup *, void *)) 625 { 626 int found, ret, nextid; 627 struct cgroup_subsys_state *css; 628 struct mem_cgroup *mem; 629 630 if (!root->use_hierarchy) 631 return (*func)(root, data); 632 633 nextid = 1; 634 do { 635 ret = 0; 636 mem = NULL; 637 638 rcu_read_lock(); 639 css = css_get_next(&mem_cgroup_subsys, nextid, &root->css, 640 &found); 641 if (css && css_tryget(css)) 642 mem = container_of(css, struct mem_cgroup, css); 643 rcu_read_unlock(); 644 645 if (mem) { 646 ret = (*func)(mem, data); 647 css_put(&mem->css); 648 } 649 nextid = found + 1; 650 } while (!ret && css); 651 652 return ret; 653 } 654 655 static inline bool mem_cgroup_is_root(struct mem_cgroup *mem) 656 { 657 return (mem == root_mem_cgroup); 658 } 659 660 /* 661 * Following LRU functions are allowed to be used without PCG_LOCK. 662 * Operations are called by routine of global LRU independently from memcg. 663 * What we have to take care of here is validness of pc->mem_cgroup. 664 * 665 * Changes to pc->mem_cgroup happens when 666 * 1. charge 667 * 2. moving account 668 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache. 669 * It is added to LRU before charge. 670 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU. 671 * When moving account, the page is not on LRU. It's isolated. 672 */ 673 674 void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru) 675 { 676 struct page_cgroup *pc; 677 struct mem_cgroup_per_zone *mz; 678 679 if (mem_cgroup_disabled()) 680 return; 681 pc = lookup_page_cgroup(page); 682 /* can happen while we handle swapcache. */ 683 if (!TestClearPageCgroupAcctLRU(pc)) 684 return; 685 VM_BUG_ON(!pc->mem_cgroup); 686 /* 687 * We don't check PCG_USED bit. It's cleared when the "page" is finally 688 * removed from global LRU. 689 */ 690 mz = page_cgroup_zoneinfo(pc); 691 MEM_CGROUP_ZSTAT(mz, lru) -= 1; 692 if (mem_cgroup_is_root(pc->mem_cgroup)) 693 return; 694 VM_BUG_ON(list_empty(&pc->lru)); 695 list_del_init(&pc->lru); 696 return; 697 } 698 699 void mem_cgroup_del_lru(struct page *page) 700 { 701 mem_cgroup_del_lru_list(page, page_lru(page)); 702 } 703 704 void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru) 705 { 706 struct mem_cgroup_per_zone *mz; 707 struct page_cgroup *pc; 708 709 if (mem_cgroup_disabled()) 710 return; 711 712 pc = lookup_page_cgroup(page); 713 /* 714 * Used bit is set without atomic ops but after smp_wmb(). 715 * For making pc->mem_cgroup visible, insert smp_rmb() here. 716 */ 717 smp_rmb(); 718 /* unused or root page is not rotated. */ 719 if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup)) 720 return; 721 mz = page_cgroup_zoneinfo(pc); 722 list_move(&pc->lru, &mz->lists[lru]); 723 } 724 725 void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru) 726 { 727 struct page_cgroup *pc; 728 struct mem_cgroup_per_zone *mz; 729 730 if (mem_cgroup_disabled()) 731 return; 732 pc = lookup_page_cgroup(page); 733 VM_BUG_ON(PageCgroupAcctLRU(pc)); 734 /* 735 * Used bit is set without atomic ops but after smp_wmb(). 736 * For making pc->mem_cgroup visible, insert smp_rmb() here. 737 */ 738 smp_rmb(); 739 if (!PageCgroupUsed(pc)) 740 return; 741 742 mz = page_cgroup_zoneinfo(pc); 743 MEM_CGROUP_ZSTAT(mz, lru) += 1; 744 SetPageCgroupAcctLRU(pc); 745 if (mem_cgroup_is_root(pc->mem_cgroup)) 746 return; 747 list_add(&pc->lru, &mz->lists[lru]); 748 } 749 750 /* 751 * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to 752 * lru because the page may.be reused after it's fully uncharged (because of 753 * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge 754 * it again. This function is only used to charge SwapCache. It's done under 755 * lock_page and expected that zone->lru_lock is never held. 756 */ 757 static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page) 758 { 759 unsigned long flags; 760 struct zone *zone = page_zone(page); 761 struct page_cgroup *pc = lookup_page_cgroup(page); 762 763 spin_lock_irqsave(&zone->lru_lock, flags); 764 /* 765 * Forget old LRU when this page_cgroup is *not* used. This Used bit 766 * is guarded by lock_page() because the page is SwapCache. 767 */ 768 if (!PageCgroupUsed(pc)) 769 mem_cgroup_del_lru_list(page, page_lru(page)); 770 spin_unlock_irqrestore(&zone->lru_lock, flags); 771 } 772 773 static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page) 774 { 775 unsigned long flags; 776 struct zone *zone = page_zone(page); 777 struct page_cgroup *pc = lookup_page_cgroup(page); 778 779 spin_lock_irqsave(&zone->lru_lock, flags); 780 /* link when the page is linked to LRU but page_cgroup isn't */ 781 if (PageLRU(page) && !PageCgroupAcctLRU(pc)) 782 mem_cgroup_add_lru_list(page, page_lru(page)); 783 spin_unlock_irqrestore(&zone->lru_lock, flags); 784 } 785 786 787 void mem_cgroup_move_lists(struct page *page, 788 enum lru_list from, enum lru_list to) 789 { 790 if (mem_cgroup_disabled()) 791 return; 792 mem_cgroup_del_lru_list(page, from); 793 mem_cgroup_add_lru_list(page, to); 794 } 795 796 int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem) 797 { 798 int ret; 799 struct mem_cgroup *curr = NULL; 800 801 task_lock(task); 802 rcu_read_lock(); 803 curr = try_get_mem_cgroup_from_mm(task->mm); 804 rcu_read_unlock(); 805 task_unlock(task); 806 if (!curr) 807 return 0; 808 /* 809 * We should check use_hierarchy of "mem" not "curr". Because checking 810 * use_hierarchy of "curr" here make this function true if hierarchy is 811 * enabled in "curr" and "curr" is a child of "mem" in *cgroup* 812 * hierarchy(even if use_hierarchy is disabled in "mem"). 813 */ 814 if (mem->use_hierarchy) 815 ret = css_is_ancestor(&curr->css, &mem->css); 816 else 817 ret = (curr == mem); 818 css_put(&curr->css); 819 return ret; 820 } 821 822 /* 823 * prev_priority control...this will be used in memory reclaim path. 824 */ 825 int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem) 826 { 827 int prev_priority; 828 829 spin_lock(&mem->reclaim_param_lock); 830 prev_priority = mem->prev_priority; 831 spin_unlock(&mem->reclaim_param_lock); 832 833 return prev_priority; 834 } 835 836 void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority) 837 { 838 spin_lock(&mem->reclaim_param_lock); 839 if (priority < mem->prev_priority) 840 mem->prev_priority = priority; 841 spin_unlock(&mem->reclaim_param_lock); 842 } 843 844 void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority) 845 { 846 spin_lock(&mem->reclaim_param_lock); 847 mem->prev_priority = priority; 848 spin_unlock(&mem->reclaim_param_lock); 849 } 850 851 static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages) 852 { 853 unsigned long active; 854 unsigned long inactive; 855 unsigned long gb; 856 unsigned long inactive_ratio; 857 858 inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_ANON); 859 active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_ANON); 860 861 gb = (inactive + active) >> (30 - PAGE_SHIFT); 862 if (gb) 863 inactive_ratio = int_sqrt(10 * gb); 864 else 865 inactive_ratio = 1; 866 867 if (present_pages) { 868 present_pages[0] = inactive; 869 present_pages[1] = active; 870 } 871 872 return inactive_ratio; 873 } 874 875 int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg) 876 { 877 unsigned long active; 878 unsigned long inactive; 879 unsigned long present_pages[2]; 880 unsigned long inactive_ratio; 881 882 inactive_ratio = calc_inactive_ratio(memcg, present_pages); 883 884 inactive = present_pages[0]; 885 active = present_pages[1]; 886 887 if (inactive * inactive_ratio < active) 888 return 1; 889 890 return 0; 891 } 892 893 int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg) 894 { 895 unsigned long active; 896 unsigned long inactive; 897 898 inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE); 899 active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE); 900 901 return (active > inactive); 902 } 903 904 unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, 905 struct zone *zone, 906 enum lru_list lru) 907 { 908 int nid = zone->zone_pgdat->node_id; 909 int zid = zone_idx(zone); 910 struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid); 911 912 return MEM_CGROUP_ZSTAT(mz, lru); 913 } 914 915 struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg, 916 struct zone *zone) 917 { 918 int nid = zone->zone_pgdat->node_id; 919 int zid = zone_idx(zone); 920 struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid); 921 922 return &mz->reclaim_stat; 923 } 924 925 struct zone_reclaim_stat * 926 mem_cgroup_get_reclaim_stat_from_page(struct page *page) 927 { 928 struct page_cgroup *pc; 929 struct mem_cgroup_per_zone *mz; 930 931 if (mem_cgroup_disabled()) 932 return NULL; 933 934 pc = lookup_page_cgroup(page); 935 /* 936 * Used bit is set without atomic ops but after smp_wmb(). 937 * For making pc->mem_cgroup visible, insert smp_rmb() here. 938 */ 939 smp_rmb(); 940 if (!PageCgroupUsed(pc)) 941 return NULL; 942 943 mz = page_cgroup_zoneinfo(pc); 944 if (!mz) 945 return NULL; 946 947 return &mz->reclaim_stat; 948 } 949 950 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, 951 struct list_head *dst, 952 unsigned long *scanned, int order, 953 int mode, struct zone *z, 954 struct mem_cgroup *mem_cont, 955 int active, int file) 956 { 957 unsigned long nr_taken = 0; 958 struct page *page; 959 unsigned long scan; 960 LIST_HEAD(pc_list); 961 struct list_head *src; 962 struct page_cgroup *pc, *tmp; 963 int nid = z->zone_pgdat->node_id; 964 int zid = zone_idx(z); 965 struct mem_cgroup_per_zone *mz; 966 int lru = LRU_FILE * file + active; 967 int ret; 968 969 BUG_ON(!mem_cont); 970 mz = mem_cgroup_zoneinfo(mem_cont, nid, zid); 971 src = &mz->lists[lru]; 972 973 scan = 0; 974 list_for_each_entry_safe_reverse(pc, tmp, src, lru) { 975 if (scan >= nr_to_scan) 976 break; 977 978 page = pc->page; 979 if (unlikely(!PageCgroupUsed(pc))) 980 continue; 981 if (unlikely(!PageLRU(page))) 982 continue; 983 984 scan++; 985 ret = __isolate_lru_page(page, mode, file); 986 switch (ret) { 987 case 0: 988 list_move(&page->lru, dst); 989 mem_cgroup_del_lru(page); 990 nr_taken++; 991 break; 992 case -EBUSY: 993 /* we don't affect global LRU but rotate in our LRU */ 994 mem_cgroup_rotate_lru_list(page, page_lru(page)); 995 break; 996 default: 997 break; 998 } 999 } 1000 1001 *scanned = scan; 1002 return nr_taken; 1003 } 1004 1005 #define mem_cgroup_from_res_counter(counter, member) \ 1006 container_of(counter, struct mem_cgroup, member) 1007 1008 static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem) 1009 { 1010 if (do_swap_account) { 1011 if (res_counter_check_under_limit(&mem->res) && 1012 res_counter_check_under_limit(&mem->memsw)) 1013 return true; 1014 } else 1015 if (res_counter_check_under_limit(&mem->res)) 1016 return true; 1017 return false; 1018 } 1019 1020 static unsigned int get_swappiness(struct mem_cgroup *memcg) 1021 { 1022 struct cgroup *cgrp = memcg->css.cgroup; 1023 unsigned int swappiness; 1024 1025 /* root ? */ 1026 if (cgrp->parent == NULL) 1027 return vm_swappiness; 1028 1029 spin_lock(&memcg->reclaim_param_lock); 1030 swappiness = memcg->swappiness; 1031 spin_unlock(&memcg->reclaim_param_lock); 1032 1033 return swappiness; 1034 } 1035 1036 static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data) 1037 { 1038 int *val = data; 1039 (*val)++; 1040 return 0; 1041 } 1042 1043 /** 1044 * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode. 1045 * @memcg: The memory cgroup that went over limit 1046 * @p: Task that is going to be killed 1047 * 1048 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is 1049 * enabled 1050 */ 1051 void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) 1052 { 1053 struct cgroup *task_cgrp; 1054 struct cgroup *mem_cgrp; 1055 /* 1056 * Need a buffer in BSS, can't rely on allocations. The code relies 1057 * on the assumption that OOM is serialized for memory controller. 1058 * If this assumption is broken, revisit this code. 1059 */ 1060 static char memcg_name[PATH_MAX]; 1061 int ret; 1062 1063 if (!memcg || !p) 1064 return; 1065 1066 1067 rcu_read_lock(); 1068 1069 mem_cgrp = memcg->css.cgroup; 1070 task_cgrp = task_cgroup(p, mem_cgroup_subsys_id); 1071 1072 ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX); 1073 if (ret < 0) { 1074 /* 1075 * Unfortunately, we are unable to convert to a useful name 1076 * But we'll still print out the usage information 1077 */ 1078 rcu_read_unlock(); 1079 goto done; 1080 } 1081 rcu_read_unlock(); 1082 1083 printk(KERN_INFO "Task in %s killed", memcg_name); 1084 1085 rcu_read_lock(); 1086 ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX); 1087 if (ret < 0) { 1088 rcu_read_unlock(); 1089 goto done; 1090 } 1091 rcu_read_unlock(); 1092 1093 /* 1094 * Continues from above, so we don't need an KERN_ level 1095 */ 1096 printk(KERN_CONT " as a result of limit of %s\n", memcg_name); 1097 done: 1098 1099 printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n", 1100 res_counter_read_u64(&memcg->res, RES_USAGE) >> 10, 1101 res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10, 1102 res_counter_read_u64(&memcg->res, RES_FAILCNT)); 1103 printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, " 1104 "failcnt %llu\n", 1105 res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10, 1106 res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10, 1107 res_counter_read_u64(&memcg->memsw, RES_FAILCNT)); 1108 } 1109 1110 /* 1111 * This function returns the number of memcg under hierarchy tree. Returns 1112 * 1(self count) if no children. 1113 */ 1114 static int mem_cgroup_count_children(struct mem_cgroup *mem) 1115 { 1116 int num = 0; 1117 mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb); 1118 return num; 1119 } 1120 1121 /* 1122 * Visit the first child (need not be the first child as per the ordering 1123 * of the cgroup list, since we track last_scanned_child) of @mem and use 1124 * that to reclaim free pages from. 1125 */ 1126 static struct mem_cgroup * 1127 mem_cgroup_select_victim(struct mem_cgroup *root_mem) 1128 { 1129 struct mem_cgroup *ret = NULL; 1130 struct cgroup_subsys_state *css; 1131 int nextid, found; 1132 1133 if (!root_mem->use_hierarchy) { 1134 css_get(&root_mem->css); 1135 ret = root_mem; 1136 } 1137 1138 while (!ret) { 1139 rcu_read_lock(); 1140 nextid = root_mem->last_scanned_child + 1; 1141 css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css, 1142 &found); 1143 if (css && css_tryget(css)) 1144 ret = container_of(css, struct mem_cgroup, css); 1145 1146 rcu_read_unlock(); 1147 /* Updates scanning parameter */ 1148 spin_lock(&root_mem->reclaim_param_lock); 1149 if (!css) { 1150 /* this means start scan from ID:1 */ 1151 root_mem->last_scanned_child = 0; 1152 } else 1153 root_mem->last_scanned_child = found; 1154 spin_unlock(&root_mem->reclaim_param_lock); 1155 } 1156 1157 return ret; 1158 } 1159 1160 /* 1161 * Scan the hierarchy if needed to reclaim memory. We remember the last child 1162 * we reclaimed from, so that we don't end up penalizing one child extensively 1163 * based on its position in the children list. 1164 * 1165 * root_mem is the original ancestor that we've been reclaim from. 1166 * 1167 * We give up and return to the caller when we visit root_mem twice. 1168 * (other groups can be removed while we're walking....) 1169 * 1170 * If shrink==true, for avoiding to free too much, this returns immedieately. 1171 */ 1172 static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem, 1173 struct zone *zone, 1174 gfp_t gfp_mask, 1175 unsigned long reclaim_options) 1176 { 1177 struct mem_cgroup *victim; 1178 int ret, total = 0; 1179 int loop = 0; 1180 bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP; 1181 bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK; 1182 bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT; 1183 unsigned long excess = mem_cgroup_get_excess(root_mem); 1184 1185 /* If memsw_is_minimum==1, swap-out is of-no-use. */ 1186 if (root_mem->memsw_is_minimum) 1187 noswap = true; 1188 1189 while (1) { 1190 victim = mem_cgroup_select_victim(root_mem); 1191 if (victim == root_mem) { 1192 loop++; 1193 if (loop >= 1) 1194 drain_all_stock_async(); 1195 if (loop >= 2) { 1196 /* 1197 * If we have not been able to reclaim 1198 * anything, it might because there are 1199 * no reclaimable pages under this hierarchy 1200 */ 1201 if (!check_soft || !total) { 1202 css_put(&victim->css); 1203 break; 1204 } 1205 /* 1206 * We want to do more targetted reclaim. 1207 * excess >> 2 is not to excessive so as to 1208 * reclaim too much, nor too less that we keep 1209 * coming back to reclaim from this cgroup 1210 */ 1211 if (total >= (excess >> 2) || 1212 (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) { 1213 css_put(&victim->css); 1214 break; 1215 } 1216 } 1217 } 1218 if (!mem_cgroup_local_usage(victim)) { 1219 /* this cgroup's local usage == 0 */ 1220 css_put(&victim->css); 1221 continue; 1222 } 1223 /* we use swappiness of local cgroup */ 1224 if (check_soft) 1225 ret = mem_cgroup_shrink_node_zone(victim, gfp_mask, 1226 noswap, get_swappiness(victim), zone, 1227 zone->zone_pgdat->node_id); 1228 else 1229 ret = try_to_free_mem_cgroup_pages(victim, gfp_mask, 1230 noswap, get_swappiness(victim)); 1231 css_put(&victim->css); 1232 /* 1233 * At shrinking usage, we can't check we should stop here or 1234 * reclaim more. It's depends on callers. last_scanned_child 1235 * will work enough for keeping fairness under tree. 1236 */ 1237 if (shrink) 1238 return ret; 1239 total += ret; 1240 if (check_soft) { 1241 if (res_counter_check_under_soft_limit(&root_mem->res)) 1242 return total; 1243 } else if (mem_cgroup_check_under_limit(root_mem)) 1244 return 1 + total; 1245 } 1246 return total; 1247 } 1248 1249 static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data) 1250 { 1251 int *val = (int *)data; 1252 int x; 1253 /* 1254 * Logically, we can stop scanning immediately when we find 1255 * a memcg is already locked. But condidering unlock ops and 1256 * creation/removal of memcg, scan-all is simple operation. 1257 */ 1258 x = atomic_inc_return(&mem->oom_lock); 1259 *val = max(x, *val); 1260 return 0; 1261 } 1262 /* 1263 * Check OOM-Killer is already running under our hierarchy. 1264 * If someone is running, return false. 1265 */ 1266 static bool mem_cgroup_oom_lock(struct mem_cgroup *mem) 1267 { 1268 int lock_count = 0; 1269 1270 mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb); 1271 1272 if (lock_count == 1) 1273 return true; 1274 return false; 1275 } 1276 1277 static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data) 1278 { 1279 /* 1280 * When a new child is created while the hierarchy is under oom, 1281 * mem_cgroup_oom_lock() may not be called. We have to use 1282 * atomic_add_unless() here. 1283 */ 1284 atomic_add_unless(&mem->oom_lock, -1, 0); 1285 return 0; 1286 } 1287 1288 static void mem_cgroup_oom_unlock(struct mem_cgroup *mem) 1289 { 1290 mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb); 1291 } 1292 1293 static DEFINE_MUTEX(memcg_oom_mutex); 1294 static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); 1295 1296 /* 1297 * try to call OOM killer. returns false if we should exit memory-reclaim loop. 1298 */ 1299 bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask) 1300 { 1301 DEFINE_WAIT(wait); 1302 bool locked; 1303 1304 /* At first, try to OOM lock hierarchy under mem.*/ 1305 mutex_lock(&memcg_oom_mutex); 1306 locked = mem_cgroup_oom_lock(mem); 1307 /* 1308 * Even if signal_pending(), we can't quit charge() loop without 1309 * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL 1310 * under OOM is always welcomed, use TASK_KILLABLE here. 1311 */ 1312 if (!locked) 1313 prepare_to_wait(&memcg_oom_waitq, &wait, TASK_KILLABLE); 1314 mutex_unlock(&memcg_oom_mutex); 1315 1316 if (locked) 1317 mem_cgroup_out_of_memory(mem, mask); 1318 else { 1319 schedule(); 1320 finish_wait(&memcg_oom_waitq, &wait); 1321 } 1322 mutex_lock(&memcg_oom_mutex); 1323 mem_cgroup_oom_unlock(mem); 1324 /* 1325 * Here, we use global waitq .....more fine grained waitq ? 1326 * Assume following hierarchy. 1327 * A/ 1328 * 01 1329 * 02 1330 * assume OOM happens both in A and 01 at the same time. Tthey are 1331 * mutually exclusive by lock. (kill in 01 helps A.) 1332 * When we use per memcg waitq, we have to wake up waiters on A and 02 1333 * in addtion to waiters on 01. We use global waitq for avoiding mess. 1334 * It will not be a big problem. 1335 * (And a task may be moved to other groups while it's waiting for OOM.) 1336 */ 1337 wake_up_all(&memcg_oom_waitq); 1338 mutex_unlock(&memcg_oom_mutex); 1339 1340 if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current)) 1341 return false; 1342 /* Give chance to dying process */ 1343 schedule_timeout(1); 1344 return true; 1345 } 1346 1347 /* 1348 * Currently used to update mapped file statistics, but the routine can be 1349 * generalized to update other statistics as well. 1350 */ 1351 void mem_cgroup_update_file_mapped(struct page *page, int val) 1352 { 1353 struct mem_cgroup *mem; 1354 struct page_cgroup *pc; 1355 1356 pc = lookup_page_cgroup(page); 1357 if (unlikely(!pc)) 1358 return; 1359 1360 lock_page_cgroup(pc); 1361 mem = pc->mem_cgroup; 1362 if (!mem || !PageCgroupUsed(pc)) 1363 goto done; 1364 1365 /* 1366 * Preemption is already disabled. We can use __this_cpu_xxx 1367 */ 1368 if (val > 0) { 1369 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]); 1370 SetPageCgroupFileMapped(pc); 1371 } else { 1372 __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]); 1373 ClearPageCgroupFileMapped(pc); 1374 } 1375 1376 done: 1377 unlock_page_cgroup(pc); 1378 } 1379 1380 /* 1381 * size of first charge trial. "32" comes from vmscan.c's magic value. 1382 * TODO: maybe necessary to use big numbers in big irons. 1383 */ 1384 #define CHARGE_SIZE (32 * PAGE_SIZE) 1385 struct memcg_stock_pcp { 1386 struct mem_cgroup *cached; /* this never be root cgroup */ 1387 int charge; 1388 struct work_struct work; 1389 }; 1390 static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); 1391 static atomic_t memcg_drain_count; 1392 1393 /* 1394 * Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed 1395 * from local stock and true is returned. If the stock is 0 or charges from a 1396 * cgroup which is not current target, returns false. This stock will be 1397 * refilled. 1398 */ 1399 static bool consume_stock(struct mem_cgroup *mem) 1400 { 1401 struct memcg_stock_pcp *stock; 1402 bool ret = true; 1403 1404 stock = &get_cpu_var(memcg_stock); 1405 if (mem == stock->cached && stock->charge) 1406 stock->charge -= PAGE_SIZE; 1407 else /* need to call res_counter_charge */ 1408 ret = false; 1409 put_cpu_var(memcg_stock); 1410 return ret; 1411 } 1412 1413 /* 1414 * Returns stocks cached in percpu to res_counter and reset cached information. 1415 */ 1416 static void drain_stock(struct memcg_stock_pcp *stock) 1417 { 1418 struct mem_cgroup *old = stock->cached; 1419 1420 if (stock->charge) { 1421 res_counter_uncharge(&old->res, stock->charge); 1422 if (do_swap_account) 1423 res_counter_uncharge(&old->memsw, stock->charge); 1424 } 1425 stock->cached = NULL; 1426 stock->charge = 0; 1427 } 1428 1429 /* 1430 * This must be called under preempt disabled or must be called by 1431 * a thread which is pinned to local cpu. 1432 */ 1433 static void drain_local_stock(struct work_struct *dummy) 1434 { 1435 struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock); 1436 drain_stock(stock); 1437 } 1438 1439 /* 1440 * Cache charges(val) which is from res_counter, to local per_cpu area. 1441 * This will be consumed by consumt_stock() function, later. 1442 */ 1443 static void refill_stock(struct mem_cgroup *mem, int val) 1444 { 1445 struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock); 1446 1447 if (stock->cached != mem) { /* reset if necessary */ 1448 drain_stock(stock); 1449 stock->cached = mem; 1450 } 1451 stock->charge += val; 1452 put_cpu_var(memcg_stock); 1453 } 1454 1455 /* 1456 * Tries to drain stocked charges in other cpus. This function is asynchronous 1457 * and just put a work per cpu for draining localy on each cpu. Caller can 1458 * expects some charges will be back to res_counter later but cannot wait for 1459 * it. 1460 */ 1461 static void drain_all_stock_async(void) 1462 { 1463 int cpu; 1464 /* This function is for scheduling "drain" in asynchronous way. 1465 * The result of "drain" is not directly handled by callers. Then, 1466 * if someone is calling drain, we don't have to call drain more. 1467 * Anyway, WORK_STRUCT_PENDING check in queue_work_on() will catch if 1468 * there is a race. We just do loose check here. 1469 */ 1470 if (atomic_read(&memcg_drain_count)) 1471 return; 1472 /* Notify other cpus that system-wide "drain" is running */ 1473 atomic_inc(&memcg_drain_count); 1474 get_online_cpus(); 1475 for_each_online_cpu(cpu) { 1476 struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); 1477 schedule_work_on(cpu, &stock->work); 1478 } 1479 put_online_cpus(); 1480 atomic_dec(&memcg_drain_count); 1481 /* We don't wait for flush_work */ 1482 } 1483 1484 /* This is a synchronous drain interface. */ 1485 static void drain_all_stock_sync(void) 1486 { 1487 /* called when force_empty is called */ 1488 atomic_inc(&memcg_drain_count); 1489 schedule_on_each_cpu(drain_local_stock); 1490 atomic_dec(&memcg_drain_count); 1491 } 1492 1493 static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb, 1494 unsigned long action, 1495 void *hcpu) 1496 { 1497 int cpu = (unsigned long)hcpu; 1498 struct memcg_stock_pcp *stock; 1499 1500 if (action != CPU_DEAD) 1501 return NOTIFY_OK; 1502 stock = &per_cpu(memcg_stock, cpu); 1503 drain_stock(stock); 1504 return NOTIFY_OK; 1505 } 1506 1507 /* 1508 * Unlike exported interface, "oom" parameter is added. if oom==true, 1509 * oom-killer can be invoked. 1510 */ 1511 static int __mem_cgroup_try_charge(struct mm_struct *mm, 1512 gfp_t gfp_mask, struct mem_cgroup **memcg, bool oom) 1513 { 1514 struct mem_cgroup *mem, *mem_over_limit; 1515 int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; 1516 struct res_counter *fail_res; 1517 int csize = CHARGE_SIZE; 1518 1519 /* 1520 * Unlike gloval-vm's OOM-kill, we're not in memory shortage 1521 * in system level. So, allow to go ahead dying process in addition to 1522 * MEMDIE process. 1523 */ 1524 if (unlikely(test_thread_flag(TIF_MEMDIE) 1525 || fatal_signal_pending(current))) 1526 goto bypass; 1527 1528 /* 1529 * We always charge the cgroup the mm_struct belongs to. 1530 * The mm_struct's mem_cgroup changes on task migration if the 1531 * thread group leader migrates. It's possible that mm is not 1532 * set, if so charge the init_mm (happens for pagecache usage). 1533 */ 1534 mem = *memcg; 1535 if (likely(!mem)) { 1536 mem = try_get_mem_cgroup_from_mm(mm); 1537 *memcg = mem; 1538 } else { 1539 css_get(&mem->css); 1540 } 1541 if (unlikely(!mem)) 1542 return 0; 1543 1544 VM_BUG_ON(css_is_removed(&mem->css)); 1545 if (mem_cgroup_is_root(mem)) 1546 goto done; 1547 1548 while (1) { 1549 int ret = 0; 1550 unsigned long flags = 0; 1551 1552 if (consume_stock(mem)) 1553 goto done; 1554 1555 ret = res_counter_charge(&mem->res, csize, &fail_res); 1556 if (likely(!ret)) { 1557 if (!do_swap_account) 1558 break; 1559 ret = res_counter_charge(&mem->memsw, csize, &fail_res); 1560 if (likely(!ret)) 1561 break; 1562 /* mem+swap counter fails */ 1563 res_counter_uncharge(&mem->res, csize); 1564 flags |= MEM_CGROUP_RECLAIM_NOSWAP; 1565 mem_over_limit = mem_cgroup_from_res_counter(fail_res, 1566 memsw); 1567 } else 1568 /* mem counter fails */ 1569 mem_over_limit = mem_cgroup_from_res_counter(fail_res, 1570 res); 1571 1572 /* reduce request size and retry */ 1573 if (csize > PAGE_SIZE) { 1574 csize = PAGE_SIZE; 1575 continue; 1576 } 1577 if (!(gfp_mask & __GFP_WAIT)) 1578 goto nomem; 1579 1580 ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL, 1581 gfp_mask, flags); 1582 if (ret) 1583 continue; 1584 1585 /* 1586 * try_to_free_mem_cgroup_pages() might not give us a full 1587 * picture of reclaim. Some pages are reclaimed and might be 1588 * moved to swap cache or just unmapped from the cgroup. 1589 * Check the limit again to see if the reclaim reduced the 1590 * current usage of the cgroup before giving up 1591 * 1592 */ 1593 if (mem_cgroup_check_under_limit(mem_over_limit)) 1594 continue; 1595 1596 /* try to avoid oom while someone is moving charge */ 1597 if (mc.moving_task && current != mc.moving_task) { 1598 struct mem_cgroup *from, *to; 1599 bool do_continue = false; 1600 /* 1601 * There is a small race that "from" or "to" can be 1602 * freed by rmdir, so we use css_tryget(). 1603 */ 1604 rcu_read_lock(); 1605 from = mc.from; 1606 to = mc.to; 1607 if (from && css_tryget(&from->css)) { 1608 if (mem_over_limit->use_hierarchy) 1609 do_continue = css_is_ancestor( 1610 &from->css, 1611 &mem_over_limit->css); 1612 else 1613 do_continue = (from == mem_over_limit); 1614 css_put(&from->css); 1615 } 1616 if (!do_continue && to && css_tryget(&to->css)) { 1617 if (mem_over_limit->use_hierarchy) 1618 do_continue = css_is_ancestor( 1619 &to->css, 1620 &mem_over_limit->css); 1621 else 1622 do_continue = (to == mem_over_limit); 1623 css_put(&to->css); 1624 } 1625 rcu_read_unlock(); 1626 if (do_continue) { 1627 DEFINE_WAIT(wait); 1628 prepare_to_wait(&mc.waitq, &wait, 1629 TASK_INTERRUPTIBLE); 1630 /* moving charge context might have finished. */ 1631 if (mc.moving_task) 1632 schedule(); 1633 finish_wait(&mc.waitq, &wait); 1634 continue; 1635 } 1636 } 1637 1638 if (!nr_retries--) { 1639 if (!oom) 1640 goto nomem; 1641 if (mem_cgroup_handle_oom(mem_over_limit, gfp_mask)) { 1642 nr_retries = MEM_CGROUP_RECLAIM_RETRIES; 1643 continue; 1644 } 1645 /* When we reach here, current task is dying .*/ 1646 css_put(&mem->css); 1647 goto bypass; 1648 } 1649 } 1650 if (csize > PAGE_SIZE) 1651 refill_stock(mem, csize - PAGE_SIZE); 1652 done: 1653 return 0; 1654 nomem: 1655 css_put(&mem->css); 1656 return -ENOMEM; 1657 bypass: 1658 *memcg = NULL; 1659 return 0; 1660 } 1661 1662 /* 1663 * Somemtimes we have to undo a charge we got by try_charge(). 1664 * This function is for that and do uncharge, put css's refcnt. 1665 * gotten by try_charge(). 1666 */ 1667 static void __mem_cgroup_cancel_charge(struct mem_cgroup *mem, 1668 unsigned long count) 1669 { 1670 if (!mem_cgroup_is_root(mem)) { 1671 res_counter_uncharge(&mem->res, PAGE_SIZE * count); 1672 if (do_swap_account) 1673 res_counter_uncharge(&mem->memsw, PAGE_SIZE * count); 1674 VM_BUG_ON(test_bit(CSS_ROOT, &mem->css.flags)); 1675 WARN_ON_ONCE(count > INT_MAX); 1676 __css_put(&mem->css, (int)count); 1677 } 1678 /* we don't need css_put for root */ 1679 } 1680 1681 static void mem_cgroup_cancel_charge(struct mem_cgroup *mem) 1682 { 1683 __mem_cgroup_cancel_charge(mem, 1); 1684 } 1685 1686 /* 1687 * A helper function to get mem_cgroup from ID. must be called under 1688 * rcu_read_lock(). The caller must check css_is_removed() or some if 1689 * it's concern. (dropping refcnt from swap can be called against removed 1690 * memcg.) 1691 */ 1692 static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) 1693 { 1694 struct cgroup_subsys_state *css; 1695 1696 /* ID 0 is unused ID */ 1697 if (!id) 1698 return NULL; 1699 css = css_lookup(&mem_cgroup_subsys, id); 1700 if (!css) 1701 return NULL; 1702 return container_of(css, struct mem_cgroup, css); 1703 } 1704 1705 struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) 1706 { 1707 struct mem_cgroup *mem = NULL; 1708 struct page_cgroup *pc; 1709 unsigned short id; 1710 swp_entry_t ent; 1711 1712 VM_BUG_ON(!PageLocked(page)); 1713 1714 pc = lookup_page_cgroup(page); 1715 lock_page_cgroup(pc); 1716 if (PageCgroupUsed(pc)) { 1717 mem = pc->mem_cgroup; 1718 if (mem && !css_tryget(&mem->css)) 1719 mem = NULL; 1720 } else if (PageSwapCache(page)) { 1721 ent.val = page_private(page); 1722 id = lookup_swap_cgroup(ent); 1723 rcu_read_lock(); 1724 mem = mem_cgroup_lookup(id); 1725 if (mem && !css_tryget(&mem->css)) 1726 mem = NULL; 1727 rcu_read_unlock(); 1728 } 1729 unlock_page_cgroup(pc); 1730 return mem; 1731 } 1732 1733 /* 1734 * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be 1735 * USED state. If already USED, uncharge and return. 1736 */ 1737 1738 static void __mem_cgroup_commit_charge(struct mem_cgroup *mem, 1739 struct page_cgroup *pc, 1740 enum charge_type ctype) 1741 { 1742 /* try_charge() can return NULL to *memcg, taking care of it. */ 1743 if (!mem) 1744 return; 1745 1746 lock_page_cgroup(pc); 1747 if (unlikely(PageCgroupUsed(pc))) { 1748 unlock_page_cgroup(pc); 1749 mem_cgroup_cancel_charge(mem); 1750 return; 1751 } 1752 1753 pc->mem_cgroup = mem; 1754 /* 1755 * We access a page_cgroup asynchronously without lock_page_cgroup(). 1756 * Especially when a page_cgroup is taken from a page, pc->mem_cgroup 1757 * is accessed after testing USED bit. To make pc->mem_cgroup visible 1758 * before USED bit, we need memory barrier here. 1759 * See mem_cgroup_add_lru_list(), etc. 1760 */ 1761 smp_wmb(); 1762 switch (ctype) { 1763 case MEM_CGROUP_CHARGE_TYPE_CACHE: 1764 case MEM_CGROUP_CHARGE_TYPE_SHMEM: 1765 SetPageCgroupCache(pc); 1766 SetPageCgroupUsed(pc); 1767 break; 1768 case MEM_CGROUP_CHARGE_TYPE_MAPPED: 1769 ClearPageCgroupCache(pc); 1770 SetPageCgroupUsed(pc); 1771 break; 1772 default: 1773 break; 1774 } 1775 1776 mem_cgroup_charge_statistics(mem, pc, true); 1777 1778 unlock_page_cgroup(pc); 1779 /* 1780 * "charge_statistics" updated event counter. Then, check it. 1781 * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree. 1782 * if they exceeds softlimit. 1783 */ 1784 memcg_check_events(mem, pc->page); 1785 } 1786 1787 /** 1788 * __mem_cgroup_move_account - move account of the page 1789 * @pc: page_cgroup of the page. 1790 * @from: mem_cgroup which the page is moved from. 1791 * @to: mem_cgroup which the page is moved to. @from != @to. 1792 * @uncharge: whether we should call uncharge and css_put against @from. 1793 * 1794 * The caller must confirm following. 1795 * - page is not on LRU (isolate_page() is useful.) 1796 * - the pc is locked, used, and ->mem_cgroup points to @from. 1797 * 1798 * This function doesn't do "charge" nor css_get to new cgroup. It should be 1799 * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is 1800 * true, this function does "uncharge" from old cgroup, but it doesn't if 1801 * @uncharge is false, so a caller should do "uncharge". 1802 */ 1803 1804 static void __mem_cgroup_move_account(struct page_cgroup *pc, 1805 struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge) 1806 { 1807 VM_BUG_ON(from == to); 1808 VM_BUG_ON(PageLRU(pc->page)); 1809 VM_BUG_ON(!PageCgroupLocked(pc)); 1810 VM_BUG_ON(!PageCgroupUsed(pc)); 1811 VM_BUG_ON(pc->mem_cgroup != from); 1812 1813 if (PageCgroupFileMapped(pc)) { 1814 /* Update mapped_file data for mem_cgroup */ 1815 preempt_disable(); 1816 __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]); 1817 __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]); 1818 preempt_enable(); 1819 } 1820 mem_cgroup_charge_statistics(from, pc, false); 1821 if (uncharge) 1822 /* This is not "cancel", but cancel_charge does all we need. */ 1823 mem_cgroup_cancel_charge(from); 1824 1825 /* caller should have done css_get */ 1826 pc->mem_cgroup = to; 1827 mem_cgroup_charge_statistics(to, pc, true); 1828 /* 1829 * We charges against "to" which may not have any tasks. Then, "to" 1830 * can be under rmdir(). But in current implementation, caller of 1831 * this function is just force_empty() and move charge, so it's 1832 * garanteed that "to" is never removed. So, we don't check rmdir 1833 * status here. 1834 */ 1835 } 1836 1837 /* 1838 * check whether the @pc is valid for moving account and call 1839 * __mem_cgroup_move_account() 1840 */ 1841 static int mem_cgroup_move_account(struct page_cgroup *pc, 1842 struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge) 1843 { 1844 int ret = -EINVAL; 1845 lock_page_cgroup(pc); 1846 if (PageCgroupUsed(pc) && pc->mem_cgroup == from) { 1847 __mem_cgroup_move_account(pc, from, to, uncharge); 1848 ret = 0; 1849 } 1850 unlock_page_cgroup(pc); 1851 /* 1852 * check events 1853 */ 1854 memcg_check_events(to, pc->page); 1855 memcg_check_events(from, pc->page); 1856 return ret; 1857 } 1858 1859 /* 1860 * move charges to its parent. 1861 */ 1862 1863 static int mem_cgroup_move_parent(struct page_cgroup *pc, 1864 struct mem_cgroup *child, 1865 gfp_t gfp_mask) 1866 { 1867 struct page *page = pc->page; 1868 struct cgroup *cg = child->css.cgroup; 1869 struct cgroup *pcg = cg->parent; 1870 struct mem_cgroup *parent; 1871 int ret; 1872 1873 /* Is ROOT ? */ 1874 if (!pcg) 1875 return -EINVAL; 1876 1877 ret = -EBUSY; 1878 if (!get_page_unless_zero(page)) 1879 goto out; 1880 if (isolate_lru_page(page)) 1881 goto put; 1882 1883 parent = mem_cgroup_from_cont(pcg); 1884 ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false); 1885 if (ret || !parent) 1886 goto put_back; 1887 1888 ret = mem_cgroup_move_account(pc, child, parent, true); 1889 if (ret) 1890 mem_cgroup_cancel_charge(parent); 1891 put_back: 1892 putback_lru_page(page); 1893 put: 1894 put_page(page); 1895 out: 1896 return ret; 1897 } 1898 1899 /* 1900 * Charge the memory controller for page usage. 1901 * Return 1902 * 0 if the charge was successful 1903 * < 0 if the cgroup is over its limit 1904 */ 1905 static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm, 1906 gfp_t gfp_mask, enum charge_type ctype, 1907 struct mem_cgroup *memcg) 1908 { 1909 struct mem_cgroup *mem; 1910 struct page_cgroup *pc; 1911 int ret; 1912 1913 pc = lookup_page_cgroup(page); 1914 /* can happen at boot */ 1915 if (unlikely(!pc)) 1916 return 0; 1917 prefetchw(pc); 1918 1919 mem = memcg; 1920 ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true); 1921 if (ret || !mem) 1922 return ret; 1923 1924 __mem_cgroup_commit_charge(mem, pc, ctype); 1925 return 0; 1926 } 1927 1928 int mem_cgroup_newpage_charge(struct page *page, 1929 struct mm_struct *mm, gfp_t gfp_mask) 1930 { 1931 if (mem_cgroup_disabled()) 1932 return 0; 1933 if (PageCompound(page)) 1934 return 0; 1935 /* 1936 * If already mapped, we don't have to account. 1937 * If page cache, page->mapping has address_space. 1938 * But page->mapping may have out-of-use anon_vma pointer, 1939 * detecit it by PageAnon() check. newly-mapped-anon's page->mapping 1940 * is NULL. 1941 */ 1942 if (page_mapped(page) || (page->mapping && !PageAnon(page))) 1943 return 0; 1944 if (unlikely(!mm)) 1945 mm = &init_mm; 1946 return mem_cgroup_charge_common(page, mm, gfp_mask, 1947 MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL); 1948 } 1949 1950 static void 1951 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr, 1952 enum charge_type ctype); 1953 1954 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, 1955 gfp_t gfp_mask) 1956 { 1957 struct mem_cgroup *mem = NULL; 1958 int ret; 1959 1960 if (mem_cgroup_disabled()) 1961 return 0; 1962 if (PageCompound(page)) 1963 return 0; 1964 /* 1965 * Corner case handling. This is called from add_to_page_cache() 1966 * in usual. But some FS (shmem) precharges this page before calling it 1967 * and call add_to_page_cache() with GFP_NOWAIT. 1968 * 1969 * For GFP_NOWAIT case, the page may be pre-charged before calling 1970 * add_to_page_cache(). (See shmem.c) check it here and avoid to call 1971 * charge twice. (It works but has to pay a bit larger cost.) 1972 * And when the page is SwapCache, it should take swap information 1973 * into account. This is under lock_page() now. 1974 */ 1975 if (!(gfp_mask & __GFP_WAIT)) { 1976 struct page_cgroup *pc; 1977 1978 1979 pc = lookup_page_cgroup(page); 1980 if (!pc) 1981 return 0; 1982 lock_page_cgroup(pc); 1983 if (PageCgroupUsed(pc)) { 1984 unlock_page_cgroup(pc); 1985 return 0; 1986 } 1987 unlock_page_cgroup(pc); 1988 } 1989 1990 if (unlikely(!mm && !mem)) 1991 mm = &init_mm; 1992 1993 if (page_is_file_cache(page)) 1994 return mem_cgroup_charge_common(page, mm, gfp_mask, 1995 MEM_CGROUP_CHARGE_TYPE_CACHE, NULL); 1996 1997 /* shmem */ 1998 if (PageSwapCache(page)) { 1999 ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem); 2000 if (!ret) 2001 __mem_cgroup_commit_charge_swapin(page, mem, 2002 MEM_CGROUP_CHARGE_TYPE_SHMEM); 2003 } else 2004 ret = mem_cgroup_charge_common(page, mm, gfp_mask, 2005 MEM_CGROUP_CHARGE_TYPE_SHMEM, mem); 2006 2007 return ret; 2008 } 2009 2010 /* 2011 * While swap-in, try_charge -> commit or cancel, the page is locked. 2012 * And when try_charge() successfully returns, one refcnt to memcg without 2013 * struct page_cgroup is acquired. This refcnt will be consumed by 2014 * "commit()" or removed by "cancel()" 2015 */ 2016 int mem_cgroup_try_charge_swapin(struct mm_struct *mm, 2017 struct page *page, 2018 gfp_t mask, struct mem_cgroup **ptr) 2019 { 2020 struct mem_cgroup *mem; 2021 int ret; 2022 2023 if (mem_cgroup_disabled()) 2024 return 0; 2025 2026 if (!do_swap_account) 2027 goto charge_cur_mm; 2028 /* 2029 * A racing thread's fault, or swapoff, may have already updated 2030 * the pte, and even removed page from swap cache: in those cases 2031 * do_swap_page()'s pte_same() test will fail; but there's also a 2032 * KSM case which does need to charge the page. 2033 */ 2034 if (!PageSwapCache(page)) 2035 goto charge_cur_mm; 2036 mem = try_get_mem_cgroup_from_page(page); 2037 if (!mem) 2038 goto charge_cur_mm; 2039 *ptr = mem; 2040 ret = __mem_cgroup_try_charge(NULL, mask, ptr, true); 2041 /* drop extra refcnt from tryget */ 2042 css_put(&mem->css); 2043 return ret; 2044 charge_cur_mm: 2045 if (unlikely(!mm)) 2046 mm = &init_mm; 2047 return __mem_cgroup_try_charge(mm, mask, ptr, true); 2048 } 2049 2050 static void 2051 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr, 2052 enum charge_type ctype) 2053 { 2054 struct page_cgroup *pc; 2055 2056 if (mem_cgroup_disabled()) 2057 return; 2058 if (!ptr) 2059 return; 2060 cgroup_exclude_rmdir(&ptr->css); 2061 pc = lookup_page_cgroup(page); 2062 mem_cgroup_lru_del_before_commit_swapcache(page); 2063 __mem_cgroup_commit_charge(ptr, pc, ctype); 2064 mem_cgroup_lru_add_after_commit_swapcache(page); 2065 /* 2066 * Now swap is on-memory. This means this page may be 2067 * counted both as mem and swap....double count. 2068 * Fix it by uncharging from memsw. Basically, this SwapCache is stable 2069 * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page() 2070 * may call delete_from_swap_cache() before reach here. 2071 */ 2072 if (do_swap_account && PageSwapCache(page)) { 2073 swp_entry_t ent = {.val = page_private(page)}; 2074 unsigned short id; 2075 struct mem_cgroup *memcg; 2076 2077 id = swap_cgroup_record(ent, 0); 2078 rcu_read_lock(); 2079 memcg = mem_cgroup_lookup(id); 2080 if (memcg) { 2081 /* 2082 * This recorded memcg can be obsolete one. So, avoid 2083 * calling css_tryget 2084 */ 2085 if (!mem_cgroup_is_root(memcg)) 2086 res_counter_uncharge(&memcg->memsw, PAGE_SIZE); 2087 mem_cgroup_swap_statistics(memcg, false); 2088 mem_cgroup_put(memcg); 2089 } 2090 rcu_read_unlock(); 2091 } 2092 /* 2093 * At swapin, we may charge account against cgroup which has no tasks. 2094 * So, rmdir()->pre_destroy() can be called while we do this charge. 2095 * In that case, we need to call pre_destroy() again. check it here. 2096 */ 2097 cgroup_release_and_wakeup_rmdir(&ptr->css); 2098 } 2099 2100 void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr) 2101 { 2102 __mem_cgroup_commit_charge_swapin(page, ptr, 2103 MEM_CGROUP_CHARGE_TYPE_MAPPED); 2104 } 2105 2106 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem) 2107 { 2108 if (mem_cgroup_disabled()) 2109 return; 2110 if (!mem) 2111 return; 2112 mem_cgroup_cancel_charge(mem); 2113 } 2114 2115 static void 2116 __do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype) 2117 { 2118 struct memcg_batch_info *batch = NULL; 2119 bool uncharge_memsw = true; 2120 /* If swapout, usage of swap doesn't decrease */ 2121 if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) 2122 uncharge_memsw = false; 2123 /* 2124 * do_batch > 0 when unmapping pages or inode invalidate/truncate. 2125 * In those cases, all pages freed continously can be expected to be in 2126 * the same cgroup and we have chance to coalesce uncharges. 2127 * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE) 2128 * because we want to do uncharge as soon as possible. 2129 */ 2130 if (!current->memcg_batch.do_batch || test_thread_flag(TIF_MEMDIE)) 2131 goto direct_uncharge; 2132 2133 batch = ¤t->memcg_batch; 2134 /* 2135 * In usual, we do css_get() when we remember memcg pointer. 2136 * But in this case, we keep res->usage until end of a series of 2137 * uncharges. Then, it's ok to ignore memcg's refcnt. 2138 */ 2139 if (!batch->memcg) 2140 batch->memcg = mem; 2141 /* 2142 * In typical case, batch->memcg == mem. This means we can 2143 * merge a series of uncharges to an uncharge of res_counter. 2144 * If not, we uncharge res_counter ony by one. 2145 */ 2146 if (batch->memcg != mem) 2147 goto direct_uncharge; 2148 /* remember freed charge and uncharge it later */ 2149 batch->bytes += PAGE_SIZE; 2150 if (uncharge_memsw) 2151 batch->memsw_bytes += PAGE_SIZE; 2152 return; 2153 direct_uncharge: 2154 res_counter_uncharge(&mem->res, PAGE_SIZE); 2155 if (uncharge_memsw) 2156 res_counter_uncharge(&mem->memsw, PAGE_SIZE); 2157 return; 2158 } 2159 2160 /* 2161 * uncharge if !page_mapped(page) 2162 */ 2163 static struct mem_cgroup * 2164 __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) 2165 { 2166 struct page_cgroup *pc; 2167 struct mem_cgroup *mem = NULL; 2168 struct mem_cgroup_per_zone *mz; 2169 2170 if (mem_cgroup_disabled()) 2171 return NULL; 2172 2173 if (PageSwapCache(page)) 2174 return NULL; 2175 2176 /* 2177 * Check if our page_cgroup is valid 2178 */ 2179 pc = lookup_page_cgroup(page); 2180 if (unlikely(!pc || !PageCgroupUsed(pc))) 2181 return NULL; 2182 2183 lock_page_cgroup(pc); 2184 2185 mem = pc->mem_cgroup; 2186 2187 if (!PageCgroupUsed(pc)) 2188 goto unlock_out; 2189 2190 switch (ctype) { 2191 case MEM_CGROUP_CHARGE_TYPE_MAPPED: 2192 case MEM_CGROUP_CHARGE_TYPE_DROP: 2193 if (page_mapped(page)) 2194 goto unlock_out; 2195 break; 2196 case MEM_CGROUP_CHARGE_TYPE_SWAPOUT: 2197 if (!PageAnon(page)) { /* Shared memory */ 2198 if (page->mapping && !page_is_file_cache(page)) 2199 goto unlock_out; 2200 } else if (page_mapped(page)) /* Anon */ 2201 goto unlock_out; 2202 break; 2203 default: 2204 break; 2205 } 2206 2207 if (!mem_cgroup_is_root(mem)) 2208 __do_uncharge(mem, ctype); 2209 if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) 2210 mem_cgroup_swap_statistics(mem, true); 2211 mem_cgroup_charge_statistics(mem, pc, false); 2212 2213 ClearPageCgroupUsed(pc); 2214 /* 2215 * pc->mem_cgroup is not cleared here. It will be accessed when it's 2216 * freed from LRU. This is safe because uncharged page is expected not 2217 * to be reused (freed soon). Exception is SwapCache, it's handled by 2218 * special functions. 2219 */ 2220 2221 mz = page_cgroup_zoneinfo(pc); 2222 unlock_page_cgroup(pc); 2223 2224 memcg_check_events(mem, page); 2225 /* at swapout, this memcg will be accessed to record to swap */ 2226 if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT) 2227 css_put(&mem->css); 2228 2229 return mem; 2230 2231 unlock_out: 2232 unlock_page_cgroup(pc); 2233 return NULL; 2234 } 2235 2236 void mem_cgroup_uncharge_page(struct page *page) 2237 { 2238 /* early check. */ 2239 if (page_mapped(page)) 2240 return; 2241 if (page->mapping && !PageAnon(page)) 2242 return; 2243 __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED); 2244 } 2245 2246 void mem_cgroup_uncharge_cache_page(struct page *page) 2247 { 2248 VM_BUG_ON(page_mapped(page)); 2249 VM_BUG_ON(page->mapping); 2250 __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE); 2251 } 2252 2253 /* 2254 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate. 2255 * In that cases, pages are freed continuously and we can expect pages 2256 * are in the same memcg. All these calls itself limits the number of 2257 * pages freed at once, then uncharge_start/end() is called properly. 2258 * This may be called prural(2) times in a context, 2259 */ 2260 2261 void mem_cgroup_uncharge_start(void) 2262 { 2263 current->memcg_batch.do_batch++; 2264 /* We can do nest. */ 2265 if (current->memcg_batch.do_batch == 1) { 2266 current->memcg_batch.memcg = NULL; 2267 current->memcg_batch.bytes = 0; 2268 current->memcg_batch.memsw_bytes = 0; 2269 } 2270 } 2271 2272 void mem_cgroup_uncharge_end(void) 2273 { 2274 struct memcg_batch_info *batch = ¤t->memcg_batch; 2275 2276 if (!batch->do_batch) 2277 return; 2278 2279 batch->do_batch--; 2280 if (batch->do_batch) /* If stacked, do nothing. */ 2281 return; 2282 2283 if (!batch->memcg) 2284 return; 2285 /* 2286 * This "batch->memcg" is valid without any css_get/put etc... 2287 * bacause we hide charges behind us. 2288 */ 2289 if (batch->bytes) 2290 res_counter_uncharge(&batch->memcg->res, batch->bytes); 2291 if (batch->memsw_bytes) 2292 res_counter_uncharge(&batch->memcg->memsw, batch->memsw_bytes); 2293 /* forget this pointer (for sanity check) */ 2294 batch->memcg = NULL; 2295 } 2296 2297 #ifdef CONFIG_SWAP 2298 /* 2299 * called after __delete_from_swap_cache() and drop "page" account. 2300 * memcg information is recorded to swap_cgroup of "ent" 2301 */ 2302 void 2303 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) 2304 { 2305 struct mem_cgroup *memcg; 2306 int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT; 2307 2308 if (!swapout) /* this was a swap cache but the swap is unused ! */ 2309 ctype = MEM_CGROUP_CHARGE_TYPE_DROP; 2310 2311 memcg = __mem_cgroup_uncharge_common(page, ctype); 2312 2313 /* record memcg information */ 2314 if (do_swap_account && swapout && memcg) { 2315 swap_cgroup_record(ent, css_id(&memcg->css)); 2316 mem_cgroup_get(memcg); 2317 } 2318 if (swapout && memcg) 2319 css_put(&memcg->css); 2320 } 2321 #endif 2322 2323 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP 2324 /* 2325 * called from swap_entry_free(). remove record in swap_cgroup and 2326 * uncharge "memsw" account. 2327 */ 2328 void mem_cgroup_uncharge_swap(swp_entry_t ent) 2329 { 2330 struct mem_cgroup *memcg; 2331 unsigned short id; 2332 2333 if (!do_swap_account) 2334 return; 2335 2336 id = swap_cgroup_record(ent, 0); 2337 rcu_read_lock(); 2338 memcg = mem_cgroup_lookup(id); 2339 if (memcg) { 2340 /* 2341 * We uncharge this because swap is freed. 2342 * This memcg can be obsolete one. We avoid calling css_tryget 2343 */ 2344 if (!mem_cgroup_is_root(memcg)) 2345 res_counter_uncharge(&memcg->memsw, PAGE_SIZE); 2346 mem_cgroup_swap_statistics(memcg, false); 2347 mem_cgroup_put(memcg); 2348 } 2349 rcu_read_unlock(); 2350 } 2351 2352 /** 2353 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. 2354 * @entry: swap entry to be moved 2355 * @from: mem_cgroup which the entry is moved from 2356 * @to: mem_cgroup which the entry is moved to 2357 * @need_fixup: whether we should fixup res_counters and refcounts. 2358 * 2359 * It succeeds only when the swap_cgroup's record for this entry is the same 2360 * as the mem_cgroup's id of @from. 2361 * 2362 * Returns 0 on success, -EINVAL on failure. 2363 * 2364 * The caller must have charged to @to, IOW, called res_counter_charge() about 2365 * both res and memsw, and called css_get(). 2366 */ 2367 static int mem_cgroup_move_swap_account(swp_entry_t entry, 2368 struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup) 2369 { 2370 unsigned short old_id, new_id; 2371 2372 old_id = css_id(&from->css); 2373 new_id = css_id(&to->css); 2374 2375 if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { 2376 mem_cgroup_swap_statistics(from, false); 2377 mem_cgroup_swap_statistics(to, true); 2378 /* 2379 * This function is only called from task migration context now. 2380 * It postpones res_counter and refcount handling till the end 2381 * of task migration(mem_cgroup_clear_mc()) for performance 2382 * improvement. But we cannot postpone mem_cgroup_get(to) 2383 * because if the process that has been moved to @to does 2384 * swap-in, the refcount of @to might be decreased to 0. 2385 */ 2386 mem_cgroup_get(to); 2387 if (need_fixup) { 2388 if (!mem_cgroup_is_root(from)) 2389 res_counter_uncharge(&from->memsw, PAGE_SIZE); 2390 mem_cgroup_put(from); 2391 /* 2392 * we charged both to->res and to->memsw, so we should 2393 * uncharge to->res. 2394 */ 2395 if (!mem_cgroup_is_root(to)) 2396 res_counter_uncharge(&to->res, PAGE_SIZE); 2397 css_put(&to->css); 2398 } 2399 return 0; 2400 } 2401 return -EINVAL; 2402 } 2403 #else 2404 static inline int mem_cgroup_move_swap_account(swp_entry_t entry, 2405 struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup) 2406 { 2407 return -EINVAL; 2408 } 2409 #endif 2410 2411 /* 2412 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old 2413 * page belongs to. 2414 */ 2415 int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr) 2416 { 2417 struct page_cgroup *pc; 2418 struct mem_cgroup *mem = NULL; 2419 int ret = 0; 2420 2421 if (mem_cgroup_disabled()) 2422 return 0; 2423 2424 pc = lookup_page_cgroup(page); 2425 lock_page_cgroup(pc); 2426 if (PageCgroupUsed(pc)) { 2427 mem = pc->mem_cgroup; 2428 css_get(&mem->css); 2429 } 2430 unlock_page_cgroup(pc); 2431 2432 if (mem) { 2433 ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false); 2434 css_put(&mem->css); 2435 } 2436 *ptr = mem; 2437 return ret; 2438 } 2439 2440 /* remove redundant charge if migration failed*/ 2441 void mem_cgroup_end_migration(struct mem_cgroup *mem, 2442 struct page *oldpage, struct page *newpage) 2443 { 2444 struct page *target, *unused; 2445 struct page_cgroup *pc; 2446 enum charge_type ctype; 2447 2448 if (!mem) 2449 return; 2450 cgroup_exclude_rmdir(&mem->css); 2451 /* at migration success, oldpage->mapping is NULL. */ 2452 if (oldpage->mapping) { 2453 target = oldpage; 2454 unused = NULL; 2455 } else { 2456 target = newpage; 2457 unused = oldpage; 2458 } 2459 2460 if (PageAnon(target)) 2461 ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED; 2462 else if (page_is_file_cache(target)) 2463 ctype = MEM_CGROUP_CHARGE_TYPE_CACHE; 2464 else 2465 ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM; 2466 2467 /* unused page is not on radix-tree now. */ 2468 if (unused) 2469 __mem_cgroup_uncharge_common(unused, ctype); 2470 2471 pc = lookup_page_cgroup(target); 2472 /* 2473 * __mem_cgroup_commit_charge() check PCG_USED bit of page_cgroup. 2474 * So, double-counting is effectively avoided. 2475 */ 2476 __mem_cgroup_commit_charge(mem, pc, ctype); 2477 2478 /* 2479 * Both of oldpage and newpage are still under lock_page(). 2480 * Then, we don't have to care about race in radix-tree. 2481 * But we have to be careful that this page is unmapped or not. 2482 * 2483 * There is a case for !page_mapped(). At the start of 2484 * migration, oldpage was mapped. But now, it's zapped. 2485 * But we know *target* page is not freed/reused under us. 2486 * mem_cgroup_uncharge_page() does all necessary checks. 2487 */ 2488 if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED) 2489 mem_cgroup_uncharge_page(target); 2490 /* 2491 * At migration, we may charge account against cgroup which has no tasks 2492 * So, rmdir()->pre_destroy() can be called while we do this charge. 2493 * In that case, we need to call pre_destroy() again. check it here. 2494 */ 2495 cgroup_release_and_wakeup_rmdir(&mem->css); 2496 } 2497 2498 /* 2499 * A call to try to shrink memory usage on charge failure at shmem's swapin. 2500 * Calling hierarchical_reclaim is not enough because we should update 2501 * last_oom_jiffies to prevent pagefault_out_of_memory from invoking global OOM. 2502 * Moreover considering hierarchy, we should reclaim from the mem_over_limit, 2503 * not from the memcg which this page would be charged to. 2504 * try_charge_swapin does all of these works properly. 2505 */ 2506 int mem_cgroup_shmem_charge_fallback(struct page *page, 2507 struct mm_struct *mm, 2508 gfp_t gfp_mask) 2509 { 2510 struct mem_cgroup *mem = NULL; 2511 int ret; 2512 2513 if (mem_cgroup_disabled()) 2514 return 0; 2515 2516 ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem); 2517 if (!ret) 2518 mem_cgroup_cancel_charge_swapin(mem); /* it does !mem check */ 2519 2520 return ret; 2521 } 2522 2523 static DEFINE_MUTEX(set_limit_mutex); 2524 2525 static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, 2526 unsigned long long val) 2527 { 2528 int retry_count; 2529 u64 memswlimit; 2530 int ret = 0; 2531 int children = mem_cgroup_count_children(memcg); 2532 u64 curusage, oldusage; 2533 2534 /* 2535 * For keeping hierarchical_reclaim simple, how long we should retry 2536 * is depends on callers. We set our retry-count to be function 2537 * of # of children which we should visit in this loop. 2538 */ 2539 retry_count = MEM_CGROUP_RECLAIM_RETRIES * children; 2540 2541 oldusage = res_counter_read_u64(&memcg->res, RES_USAGE); 2542 2543 while (retry_count) { 2544 if (signal_pending(current)) { 2545 ret = -EINTR; 2546 break; 2547 } 2548 /* 2549 * Rather than hide all in some function, I do this in 2550 * open coded manner. You see what this really does. 2551 * We have to guarantee mem->res.limit < mem->memsw.limit. 2552 */ 2553 mutex_lock(&set_limit_mutex); 2554 memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 2555 if (memswlimit < val) { 2556 ret = -EINVAL; 2557 mutex_unlock(&set_limit_mutex); 2558 break; 2559 } 2560 ret = res_counter_set_limit(&memcg->res, val); 2561 if (!ret) { 2562 if (memswlimit == val) 2563 memcg->memsw_is_minimum = true; 2564 else 2565 memcg->memsw_is_minimum = false; 2566 } 2567 mutex_unlock(&set_limit_mutex); 2568 2569 if (!ret) 2570 break; 2571 2572 mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL, 2573 MEM_CGROUP_RECLAIM_SHRINK); 2574 curusage = res_counter_read_u64(&memcg->res, RES_USAGE); 2575 /* Usage is reduced ? */ 2576 if (curusage >= oldusage) 2577 retry_count--; 2578 else 2579 oldusage = curusage; 2580 } 2581 2582 return ret; 2583 } 2584 2585 static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, 2586 unsigned long long val) 2587 { 2588 int retry_count; 2589 u64 memlimit, oldusage, curusage; 2590 int children = mem_cgroup_count_children(memcg); 2591 int ret = -EBUSY; 2592 2593 /* see mem_cgroup_resize_res_limit */ 2594 retry_count = children * MEM_CGROUP_RECLAIM_RETRIES; 2595 oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); 2596 while (retry_count) { 2597 if (signal_pending(current)) { 2598 ret = -EINTR; 2599 break; 2600 } 2601 /* 2602 * Rather than hide all in some function, I do this in 2603 * open coded manner. You see what this really does. 2604 * We have to guarantee mem->res.limit < mem->memsw.limit. 2605 */ 2606 mutex_lock(&set_limit_mutex); 2607 memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT); 2608 if (memlimit > val) { 2609 ret = -EINVAL; 2610 mutex_unlock(&set_limit_mutex); 2611 break; 2612 } 2613 ret = res_counter_set_limit(&memcg->memsw, val); 2614 if (!ret) { 2615 if (memlimit == val) 2616 memcg->memsw_is_minimum = true; 2617 else 2618 memcg->memsw_is_minimum = false; 2619 } 2620 mutex_unlock(&set_limit_mutex); 2621 2622 if (!ret) 2623 break; 2624 2625 mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL, 2626 MEM_CGROUP_RECLAIM_NOSWAP | 2627 MEM_CGROUP_RECLAIM_SHRINK); 2628 curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); 2629 /* Usage is reduced ? */ 2630 if (curusage >= oldusage) 2631 retry_count--; 2632 else 2633 oldusage = curusage; 2634 } 2635 return ret; 2636 } 2637 2638 unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, 2639 gfp_t gfp_mask, int nid, 2640 int zid) 2641 { 2642 unsigned long nr_reclaimed = 0; 2643 struct mem_cgroup_per_zone *mz, *next_mz = NULL; 2644 unsigned long reclaimed; 2645 int loop = 0; 2646 struct mem_cgroup_tree_per_zone *mctz; 2647 unsigned long long excess; 2648 2649 if (order > 0) 2650 return 0; 2651 2652 mctz = soft_limit_tree_node_zone(nid, zid); 2653 /* 2654 * This loop can run a while, specially if mem_cgroup's continuously 2655 * keep exceeding their soft limit and putting the system under 2656 * pressure 2657 */ 2658 do { 2659 if (next_mz) 2660 mz = next_mz; 2661 else 2662 mz = mem_cgroup_largest_soft_limit_node(mctz); 2663 if (!mz) 2664 break; 2665 2666 reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone, 2667 gfp_mask, 2668 MEM_CGROUP_RECLAIM_SOFT); 2669 nr_reclaimed += reclaimed; 2670 spin_lock(&mctz->lock); 2671 2672 /* 2673 * If we failed to reclaim anything from this memory cgroup 2674 * it is time to move on to the next cgroup 2675 */ 2676 next_mz = NULL; 2677 if (!reclaimed) { 2678 do { 2679 /* 2680 * Loop until we find yet another one. 2681 * 2682 * By the time we get the soft_limit lock 2683 * again, someone might have aded the 2684 * group back on the RB tree. Iterate to 2685 * make sure we get a different mem. 2686 * mem_cgroup_largest_soft_limit_node returns 2687 * NULL if no other cgroup is present on 2688 * the tree 2689 */ 2690 next_mz = 2691 __mem_cgroup_largest_soft_limit_node(mctz); 2692 if (next_mz == mz) { 2693 css_put(&next_mz->mem->css); 2694 next_mz = NULL; 2695 } else /* next_mz == NULL or other memcg */ 2696 break; 2697 } while (1); 2698 } 2699 __mem_cgroup_remove_exceeded(mz->mem, mz, mctz); 2700 excess = res_counter_soft_limit_excess(&mz->mem->res); 2701 /* 2702 * One school of thought says that we should not add 2703 * back the node to the tree if reclaim returns 0. 2704 * But our reclaim could return 0, simply because due 2705 * to priority we are exposing a smaller subset of 2706 * memory to reclaim from. Consider this as a longer 2707 * term TODO. 2708 */ 2709 /* If excess == 0, no tree ops */ 2710 __mem_cgroup_insert_exceeded(mz->mem, mz, mctz, excess); 2711 spin_unlock(&mctz->lock); 2712 css_put(&mz->mem->css); 2713 loop++; 2714 /* 2715 * Could not reclaim anything and there are no more 2716 * mem cgroups to try or we seem to be looping without 2717 * reclaiming anything. 2718 */ 2719 if (!nr_reclaimed && 2720 (next_mz == NULL || 2721 loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS)) 2722 break; 2723 } while (!nr_reclaimed); 2724 if (next_mz) 2725 css_put(&next_mz->mem->css); 2726 return nr_reclaimed; 2727 } 2728 2729 /* 2730 * This routine traverse page_cgroup in given list and drop them all. 2731 * *And* this routine doesn't reclaim page itself, just removes page_cgroup. 2732 */ 2733 static int mem_cgroup_force_empty_list(struct mem_cgroup *mem, 2734 int node, int zid, enum lru_list lru) 2735 { 2736 struct zone *zone; 2737 struct mem_cgroup_per_zone *mz; 2738 struct page_cgroup *pc, *busy; 2739 unsigned long flags, loop; 2740 struct list_head *list; 2741 int ret = 0; 2742 2743 zone = &NODE_DATA(node)->node_zones[zid]; 2744 mz = mem_cgroup_zoneinfo(mem, node, zid); 2745 list = &mz->lists[lru]; 2746 2747 loop = MEM_CGROUP_ZSTAT(mz, lru); 2748 /* give some margin against EBUSY etc...*/ 2749 loop += 256; 2750 busy = NULL; 2751 while (loop--) { 2752 ret = 0; 2753 spin_lock_irqsave(&zone->lru_lock, flags); 2754 if (list_empty(list)) { 2755 spin_unlock_irqrestore(&zone->lru_lock, flags); 2756 break; 2757 } 2758 pc = list_entry(list->prev, struct page_cgroup, lru); 2759 if (busy == pc) { 2760 list_move(&pc->lru, list); 2761 busy = NULL; 2762 spin_unlock_irqrestore(&zone->lru_lock, flags); 2763 continue; 2764 } 2765 spin_unlock_irqrestore(&zone->lru_lock, flags); 2766 2767 ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL); 2768 if (ret == -ENOMEM) 2769 break; 2770 2771 if (ret == -EBUSY || ret == -EINVAL) { 2772 /* found lock contention or "pc" is obsolete. */ 2773 busy = pc; 2774 cond_resched(); 2775 } else 2776 busy = NULL; 2777 } 2778 2779 if (!ret && !list_empty(list)) 2780 return -EBUSY; 2781 return ret; 2782 } 2783 2784 /* 2785 * make mem_cgroup's charge to be 0 if there is no task. 2786 * This enables deleting this mem_cgroup. 2787 */ 2788 static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all) 2789 { 2790 int ret; 2791 int node, zid, shrink; 2792 int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; 2793 struct cgroup *cgrp = mem->css.cgroup; 2794 2795 css_get(&mem->css); 2796 2797 shrink = 0; 2798 /* should free all ? */ 2799 if (free_all) 2800 goto try_to_free; 2801 move_account: 2802 do { 2803 ret = -EBUSY; 2804 if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children)) 2805 goto out; 2806 ret = -EINTR; 2807 if (signal_pending(current)) 2808 goto out; 2809 /* This is for making all *used* pages to be on LRU. */ 2810 lru_add_drain_all(); 2811 drain_all_stock_sync(); 2812 ret = 0; 2813 for_each_node_state(node, N_HIGH_MEMORY) { 2814 for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) { 2815 enum lru_list l; 2816 for_each_lru(l) { 2817 ret = mem_cgroup_force_empty_list(mem, 2818 node, zid, l); 2819 if (ret) 2820 break; 2821 } 2822 } 2823 if (ret) 2824 break; 2825 } 2826 /* it seems parent cgroup doesn't have enough mem */ 2827 if (ret == -ENOMEM) 2828 goto try_to_free; 2829 cond_resched(); 2830 /* "ret" should also be checked to ensure all lists are empty. */ 2831 } while (mem->res.usage > 0 || ret); 2832 out: 2833 css_put(&mem->css); 2834 return ret; 2835 2836 try_to_free: 2837 /* returns EBUSY if there is a task or if we come here twice. */ 2838 if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) { 2839 ret = -EBUSY; 2840 goto out; 2841 } 2842 /* we call try-to-free pages for make this cgroup empty */ 2843 lru_add_drain_all(); 2844 /* try to free all pages in this cgroup */ 2845 shrink = 1; 2846 while (nr_retries && mem->res.usage > 0) { 2847 int progress; 2848 2849 if (signal_pending(current)) { 2850 ret = -EINTR; 2851 goto out; 2852 } 2853 progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL, 2854 false, get_swappiness(mem)); 2855 if (!progress) { 2856 nr_retries--; 2857 /* maybe some writeback is necessary */ 2858 congestion_wait(BLK_RW_ASYNC, HZ/10); 2859 } 2860 2861 } 2862 lru_add_drain(); 2863 /* try move_account...there may be some *locked* pages. */ 2864 goto move_account; 2865 } 2866 2867 int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event) 2868 { 2869 return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true); 2870 } 2871 2872 2873 static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft) 2874 { 2875 return mem_cgroup_from_cont(cont)->use_hierarchy; 2876 } 2877 2878 static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft, 2879 u64 val) 2880 { 2881 int retval = 0; 2882 struct mem_cgroup *mem = mem_cgroup_from_cont(cont); 2883 struct cgroup *parent = cont->parent; 2884 struct mem_cgroup *parent_mem = NULL; 2885 2886 if (parent) 2887 parent_mem = mem_cgroup_from_cont(parent); 2888 2889 cgroup_lock(); 2890 /* 2891 * If parent's use_hierarchy is set, we can't make any modifications 2892 * in the child subtrees. If it is unset, then the change can 2893 * occur, provided the current cgroup has no children. 2894 * 2895 * For the root cgroup, parent_mem is NULL, we allow value to be 2896 * set if there are no children. 2897 */ 2898 if ((!parent_mem || !parent_mem->use_hierarchy) && 2899 (val == 1 || val == 0)) { 2900 if (list_empty(&cont->children)) 2901 mem->use_hierarchy = val; 2902 else 2903 retval = -EBUSY; 2904 } else 2905 retval = -EINVAL; 2906 cgroup_unlock(); 2907 2908 return retval; 2909 } 2910 2911 struct mem_cgroup_idx_data { 2912 s64 val; 2913 enum mem_cgroup_stat_index idx; 2914 }; 2915 2916 static int 2917 mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data) 2918 { 2919 struct mem_cgroup_idx_data *d = data; 2920 d->val += mem_cgroup_read_stat(mem, d->idx); 2921 return 0; 2922 } 2923 2924 static void 2925 mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem, 2926 enum mem_cgroup_stat_index idx, s64 *val) 2927 { 2928 struct mem_cgroup_idx_data d; 2929 d.idx = idx; 2930 d.val = 0; 2931 mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat); 2932 *val = d.val; 2933 } 2934 2935 static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap) 2936 { 2937 u64 idx_val, val; 2938 2939 if (!mem_cgroup_is_root(mem)) { 2940 if (!swap) 2941 return res_counter_read_u64(&mem->res, RES_USAGE); 2942 else 2943 return res_counter_read_u64(&mem->memsw, RES_USAGE); 2944 } 2945 2946 mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE, &idx_val); 2947 val = idx_val; 2948 mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS, &idx_val); 2949 val += idx_val; 2950 2951 if (swap) { 2952 mem_cgroup_get_recursive_idx_stat(mem, 2953 MEM_CGROUP_STAT_SWAPOUT, &idx_val); 2954 val += idx_val; 2955 } 2956 2957 return val << PAGE_SHIFT; 2958 } 2959 2960 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft) 2961 { 2962 struct mem_cgroup *mem = mem_cgroup_from_cont(cont); 2963 u64 val; 2964 int type, name; 2965 2966 type = MEMFILE_TYPE(cft->private); 2967 name = MEMFILE_ATTR(cft->private); 2968 switch (type) { 2969 case _MEM: 2970 if (name == RES_USAGE) 2971 val = mem_cgroup_usage(mem, false); 2972 else 2973 val = res_counter_read_u64(&mem->res, name); 2974 break; 2975 case _MEMSWAP: 2976 if (name == RES_USAGE) 2977 val = mem_cgroup_usage(mem, true); 2978 else 2979 val = res_counter_read_u64(&mem->memsw, name); 2980 break; 2981 default: 2982 BUG(); 2983 break; 2984 } 2985 return val; 2986 } 2987 /* 2988 * The user of this function is... 2989 * RES_LIMIT. 2990 */ 2991 static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft, 2992 const char *buffer) 2993 { 2994 struct mem_cgroup *memcg = mem_cgroup_from_cont(cont); 2995 int type, name; 2996 unsigned long long val; 2997 int ret; 2998 2999 type = MEMFILE_TYPE(cft->private); 3000 name = MEMFILE_ATTR(cft->private); 3001 switch (name) { 3002 case RES_LIMIT: 3003 if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */ 3004 ret = -EINVAL; 3005 break; 3006 } 3007 /* This function does all necessary parse...reuse it */ 3008 ret = res_counter_memparse_write_strategy(buffer, &val); 3009 if (ret) 3010 break; 3011 if (type == _MEM) 3012 ret = mem_cgroup_resize_limit(memcg, val); 3013 else 3014 ret = mem_cgroup_resize_memsw_limit(memcg, val); 3015 break; 3016 case RES_SOFT_LIMIT: 3017 ret = res_counter_memparse_write_strategy(buffer, &val); 3018 if (ret) 3019 break; 3020 /* 3021 * For memsw, soft limits are hard to implement in terms 3022 * of semantics, for now, we support soft limits for 3023 * control without swap 3024 */ 3025 if (type == _MEM) 3026 ret = res_counter_set_soft_limit(&memcg->res, val); 3027 else 3028 ret = -EINVAL; 3029 break; 3030 default: 3031 ret = -EINVAL; /* should be BUG() ? */ 3032 break; 3033 } 3034 return ret; 3035 } 3036 3037 static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg, 3038 unsigned long long *mem_limit, unsigned long long *memsw_limit) 3039 { 3040 struct cgroup *cgroup; 3041 unsigned long long min_limit, min_memsw_limit, tmp; 3042 3043 min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT); 3044 min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 3045 cgroup = memcg->css.cgroup; 3046 if (!memcg->use_hierarchy) 3047 goto out; 3048 3049 while (cgroup->parent) { 3050 cgroup = cgroup->parent; 3051 memcg = mem_cgroup_from_cont(cgroup); 3052 if (!memcg->use_hierarchy) 3053 break; 3054 tmp = res_counter_read_u64(&memcg->res, RES_LIMIT); 3055 min_limit = min(min_limit, tmp); 3056 tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 3057 min_memsw_limit = min(min_memsw_limit, tmp); 3058 } 3059 out: 3060 *mem_limit = min_limit; 3061 *memsw_limit = min_memsw_limit; 3062 return; 3063 } 3064 3065 static int mem_cgroup_reset(struct cgroup *cont, unsigned int event) 3066 { 3067 struct mem_cgroup *mem; 3068 int type, name; 3069 3070 mem = mem_cgroup_from_cont(cont); 3071 type = MEMFILE_TYPE(event); 3072 name = MEMFILE_ATTR(event); 3073 switch (name) { 3074 case RES_MAX_USAGE: 3075 if (type == _MEM) 3076 res_counter_reset_max(&mem->res); 3077 else 3078 res_counter_reset_max(&mem->memsw); 3079 break; 3080 case RES_FAILCNT: 3081 if (type == _MEM) 3082 res_counter_reset_failcnt(&mem->res); 3083 else 3084 res_counter_reset_failcnt(&mem->memsw); 3085 break; 3086 } 3087 3088 return 0; 3089 } 3090 3091 static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp, 3092 struct cftype *cft) 3093 { 3094 return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate; 3095 } 3096 3097 #ifdef CONFIG_MMU 3098 static int mem_cgroup_move_charge_write(struct cgroup *cgrp, 3099 struct cftype *cft, u64 val) 3100 { 3101 struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp); 3102 3103 if (val >= (1 << NR_MOVE_TYPE)) 3104 return -EINVAL; 3105 /* 3106 * We check this value several times in both in can_attach() and 3107 * attach(), so we need cgroup lock to prevent this value from being 3108 * inconsistent. 3109 */ 3110 cgroup_lock(); 3111 mem->move_charge_at_immigrate = val; 3112 cgroup_unlock(); 3113 3114 return 0; 3115 } 3116 #else 3117 static int mem_cgroup_move_charge_write(struct cgroup *cgrp, 3118 struct cftype *cft, u64 val) 3119 { 3120 return -ENOSYS; 3121 } 3122 #endif 3123 3124 3125 /* For read statistics */ 3126 enum { 3127 MCS_CACHE, 3128 MCS_RSS, 3129 MCS_FILE_MAPPED, 3130 MCS_PGPGIN, 3131 MCS_PGPGOUT, 3132 MCS_SWAP, 3133 MCS_INACTIVE_ANON, 3134 MCS_ACTIVE_ANON, 3135 MCS_INACTIVE_FILE, 3136 MCS_ACTIVE_FILE, 3137 MCS_UNEVICTABLE, 3138 NR_MCS_STAT, 3139 }; 3140 3141 struct mcs_total_stat { 3142 s64 stat[NR_MCS_STAT]; 3143 }; 3144 3145 struct { 3146 char *local_name; 3147 char *total_name; 3148 } memcg_stat_strings[NR_MCS_STAT] = { 3149 {"cache", "total_cache"}, 3150 {"rss", "total_rss"}, 3151 {"mapped_file", "total_mapped_file"}, 3152 {"pgpgin", "total_pgpgin"}, 3153 {"pgpgout", "total_pgpgout"}, 3154 {"swap", "total_swap"}, 3155 {"inactive_anon", "total_inactive_anon"}, 3156 {"active_anon", "total_active_anon"}, 3157 {"inactive_file", "total_inactive_file"}, 3158 {"active_file", "total_active_file"}, 3159 {"unevictable", "total_unevictable"} 3160 }; 3161 3162 3163 static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data) 3164 { 3165 struct mcs_total_stat *s = data; 3166 s64 val; 3167 3168 /* per cpu stat */ 3169 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE); 3170 s->stat[MCS_CACHE] += val * PAGE_SIZE; 3171 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS); 3172 s->stat[MCS_RSS] += val * PAGE_SIZE; 3173 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_MAPPED); 3174 s->stat[MCS_FILE_MAPPED] += val * PAGE_SIZE; 3175 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGIN_COUNT); 3176 s->stat[MCS_PGPGIN] += val; 3177 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_PGPGOUT_COUNT); 3178 s->stat[MCS_PGPGOUT] += val; 3179 if (do_swap_account) { 3180 val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT); 3181 s->stat[MCS_SWAP] += val * PAGE_SIZE; 3182 } 3183 3184 /* per zone stat */ 3185 val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON); 3186 s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE; 3187 val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_ANON); 3188 s->stat[MCS_ACTIVE_ANON] += val * PAGE_SIZE; 3189 val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_FILE); 3190 s->stat[MCS_INACTIVE_FILE] += val * PAGE_SIZE; 3191 val = mem_cgroup_get_local_zonestat(mem, LRU_ACTIVE_FILE); 3192 s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE; 3193 val = mem_cgroup_get_local_zonestat(mem, LRU_UNEVICTABLE); 3194 s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE; 3195 return 0; 3196 } 3197 3198 static void 3199 mem_cgroup_get_total_stat(struct mem_cgroup *mem, struct mcs_total_stat *s) 3200 { 3201 mem_cgroup_walk_tree(mem, s, mem_cgroup_get_local_stat); 3202 } 3203 3204 static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft, 3205 struct cgroup_map_cb *cb) 3206 { 3207 struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont); 3208 struct mcs_total_stat mystat; 3209 int i; 3210 3211 memset(&mystat, 0, sizeof(mystat)); 3212 mem_cgroup_get_local_stat(mem_cont, &mystat); 3213 3214 for (i = 0; i < NR_MCS_STAT; i++) { 3215 if (i == MCS_SWAP && !do_swap_account) 3216 continue; 3217 cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]); 3218 } 3219 3220 /* Hierarchical information */ 3221 { 3222 unsigned long long limit, memsw_limit; 3223 memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit); 3224 cb->fill(cb, "hierarchical_memory_limit", limit); 3225 if (do_swap_account) 3226 cb->fill(cb, "hierarchical_memsw_limit", memsw_limit); 3227 } 3228 3229 memset(&mystat, 0, sizeof(mystat)); 3230 mem_cgroup_get_total_stat(mem_cont, &mystat); 3231 for (i = 0; i < NR_MCS_STAT; i++) { 3232 if (i == MCS_SWAP && !do_swap_account) 3233 continue; 3234 cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]); 3235 } 3236 3237 #ifdef CONFIG_DEBUG_VM 3238 cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL)); 3239 3240 { 3241 int nid, zid; 3242 struct mem_cgroup_per_zone *mz; 3243 unsigned long recent_rotated[2] = {0, 0}; 3244 unsigned long recent_scanned[2] = {0, 0}; 3245 3246 for_each_online_node(nid) 3247 for (zid = 0; zid < MAX_NR_ZONES; zid++) { 3248 mz = mem_cgroup_zoneinfo(mem_cont, nid, zid); 3249 3250 recent_rotated[0] += 3251 mz->reclaim_stat.recent_rotated[0]; 3252 recent_rotated[1] += 3253 mz->reclaim_stat.recent_rotated[1]; 3254 recent_scanned[0] += 3255 mz->reclaim_stat.recent_scanned[0]; 3256 recent_scanned[1] += 3257 mz->reclaim_stat.recent_scanned[1]; 3258 } 3259 cb->fill(cb, "recent_rotated_anon", recent_rotated[0]); 3260 cb->fill(cb, "recent_rotated_file", recent_rotated[1]); 3261 cb->fill(cb, "recent_scanned_anon", recent_scanned[0]); 3262 cb->fill(cb, "recent_scanned_file", recent_scanned[1]); 3263 } 3264 #endif 3265 3266 return 0; 3267 } 3268 3269 static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft) 3270 { 3271 struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); 3272 3273 return get_swappiness(memcg); 3274 } 3275 3276 static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft, 3277 u64 val) 3278 { 3279 struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); 3280 struct mem_cgroup *parent; 3281 3282 if (val > 100) 3283 return -EINVAL; 3284 3285 if (cgrp->parent == NULL) 3286 return -EINVAL; 3287 3288 parent = mem_cgroup_from_cont(cgrp->parent); 3289 3290 cgroup_lock(); 3291 3292 /* If under hierarchy, only empty-root can set this value */ 3293 if ((parent->use_hierarchy) || 3294 (memcg->use_hierarchy && !list_empty(&cgrp->children))) { 3295 cgroup_unlock(); 3296 return -EINVAL; 3297 } 3298 3299 spin_lock(&memcg->reclaim_param_lock); 3300 memcg->swappiness = val; 3301 spin_unlock(&memcg->reclaim_param_lock); 3302 3303 cgroup_unlock(); 3304 3305 return 0; 3306 } 3307 3308 static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) 3309 { 3310 struct mem_cgroup_threshold_ary *t; 3311 u64 usage; 3312 int i; 3313 3314 rcu_read_lock(); 3315 if (!swap) 3316 t = rcu_dereference(memcg->thresholds); 3317 else 3318 t = rcu_dereference(memcg->memsw_thresholds); 3319 3320 if (!t) 3321 goto unlock; 3322 3323 usage = mem_cgroup_usage(memcg, swap); 3324 3325 /* 3326 * current_threshold points to threshold just below usage. 3327 * If it's not true, a threshold was crossed after last 3328 * call of __mem_cgroup_threshold(). 3329 */ 3330 i = atomic_read(&t->current_threshold); 3331 3332 /* 3333 * Iterate backward over array of thresholds starting from 3334 * current_threshold and check if a threshold is crossed. 3335 * If none of thresholds below usage is crossed, we read 3336 * only one element of the array here. 3337 */ 3338 for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--) 3339 eventfd_signal(t->entries[i].eventfd, 1); 3340 3341 /* i = current_threshold + 1 */ 3342 i++; 3343 3344 /* 3345 * Iterate forward over array of thresholds starting from 3346 * current_threshold+1 and check if a threshold is crossed. 3347 * If none of thresholds above usage is crossed, we read 3348 * only one element of the array here. 3349 */ 3350 for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++) 3351 eventfd_signal(t->entries[i].eventfd, 1); 3352 3353 /* Update current_threshold */ 3354 atomic_set(&t->current_threshold, i - 1); 3355 unlock: 3356 rcu_read_unlock(); 3357 } 3358 3359 static void mem_cgroup_threshold(struct mem_cgroup *memcg) 3360 { 3361 __mem_cgroup_threshold(memcg, false); 3362 if (do_swap_account) 3363 __mem_cgroup_threshold(memcg, true); 3364 } 3365 3366 static int compare_thresholds(const void *a, const void *b) 3367 { 3368 const struct mem_cgroup_threshold *_a = a; 3369 const struct mem_cgroup_threshold *_b = b; 3370 3371 return _a->threshold - _b->threshold; 3372 } 3373 3374 static int mem_cgroup_register_event(struct cgroup *cgrp, struct cftype *cft, 3375 struct eventfd_ctx *eventfd, const char *args) 3376 { 3377 struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); 3378 struct mem_cgroup_threshold_ary *thresholds, *thresholds_new; 3379 int type = MEMFILE_TYPE(cft->private); 3380 u64 threshold, usage; 3381 int size; 3382 int i, ret; 3383 3384 ret = res_counter_memparse_write_strategy(args, &threshold); 3385 if (ret) 3386 return ret; 3387 3388 mutex_lock(&memcg->thresholds_lock); 3389 if (type == _MEM) 3390 thresholds = memcg->thresholds; 3391 else if (type == _MEMSWAP) 3392 thresholds = memcg->memsw_thresholds; 3393 else 3394 BUG(); 3395 3396 usage = mem_cgroup_usage(memcg, type == _MEMSWAP); 3397 3398 /* Check if a threshold crossed before adding a new one */ 3399 if (thresholds) 3400 __mem_cgroup_threshold(memcg, type == _MEMSWAP); 3401 3402 if (thresholds) 3403 size = thresholds->size + 1; 3404 else 3405 size = 1; 3406 3407 /* Allocate memory for new array of thresholds */ 3408 thresholds_new = kmalloc(sizeof(*thresholds_new) + 3409 size * sizeof(struct mem_cgroup_threshold), 3410 GFP_KERNEL); 3411 if (!thresholds_new) { 3412 ret = -ENOMEM; 3413 goto unlock; 3414 } 3415 thresholds_new->size = size; 3416 3417 /* Copy thresholds (if any) to new array */ 3418 if (thresholds) 3419 memcpy(thresholds_new->entries, thresholds->entries, 3420 thresholds->size * 3421 sizeof(struct mem_cgroup_threshold)); 3422 /* Add new threshold */ 3423 thresholds_new->entries[size - 1].eventfd = eventfd; 3424 thresholds_new->entries[size - 1].threshold = threshold; 3425 3426 /* Sort thresholds. Registering of new threshold isn't time-critical */ 3427 sort(thresholds_new->entries, size, 3428 sizeof(struct mem_cgroup_threshold), 3429 compare_thresholds, NULL); 3430 3431 /* Find current threshold */ 3432 atomic_set(&thresholds_new->current_threshold, -1); 3433 for (i = 0; i < size; i++) { 3434 if (thresholds_new->entries[i].threshold < usage) { 3435 /* 3436 * thresholds_new->current_threshold will not be used 3437 * until rcu_assign_pointer(), so it's safe to increment 3438 * it here. 3439 */ 3440 atomic_inc(&thresholds_new->current_threshold); 3441 } 3442 } 3443 3444 if (type == _MEM) 3445 rcu_assign_pointer(memcg->thresholds, thresholds_new); 3446 else 3447 rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new); 3448 3449 /* To be sure that nobody uses thresholds before freeing it */ 3450 synchronize_rcu(); 3451 3452 kfree(thresholds); 3453 unlock: 3454 mutex_unlock(&memcg->thresholds_lock); 3455 3456 return ret; 3457 } 3458 3459 static int mem_cgroup_unregister_event(struct cgroup *cgrp, struct cftype *cft, 3460 struct eventfd_ctx *eventfd) 3461 { 3462 struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); 3463 struct mem_cgroup_threshold_ary *thresholds, *thresholds_new; 3464 int type = MEMFILE_TYPE(cft->private); 3465 u64 usage; 3466 int size = 0; 3467 int i, j, ret; 3468 3469 mutex_lock(&memcg->thresholds_lock); 3470 if (type == _MEM) 3471 thresholds = memcg->thresholds; 3472 else if (type == _MEMSWAP) 3473 thresholds = memcg->memsw_thresholds; 3474 else 3475 BUG(); 3476 3477 /* 3478 * Something went wrong if we trying to unregister a threshold 3479 * if we don't have thresholds 3480 */ 3481 BUG_ON(!thresholds); 3482 3483 usage = mem_cgroup_usage(memcg, type == _MEMSWAP); 3484 3485 /* Check if a threshold crossed before removing */ 3486 __mem_cgroup_threshold(memcg, type == _MEMSWAP); 3487 3488 /* Calculate new number of threshold */ 3489 for (i = 0; i < thresholds->size; i++) { 3490 if (thresholds->entries[i].eventfd != eventfd) 3491 size++; 3492 } 3493 3494 /* Set thresholds array to NULL if we don't have thresholds */ 3495 if (!size) { 3496 thresholds_new = NULL; 3497 goto assign; 3498 } 3499 3500 /* Allocate memory for new array of thresholds */ 3501 thresholds_new = kmalloc(sizeof(*thresholds_new) + 3502 size * sizeof(struct mem_cgroup_threshold), 3503 GFP_KERNEL); 3504 if (!thresholds_new) { 3505 ret = -ENOMEM; 3506 goto unlock; 3507 } 3508 thresholds_new->size = size; 3509 3510 /* Copy thresholds and find current threshold */ 3511 atomic_set(&thresholds_new->current_threshold, -1); 3512 for (i = 0, j = 0; i < thresholds->size; i++) { 3513 if (thresholds->entries[i].eventfd == eventfd) 3514 continue; 3515 3516 thresholds_new->entries[j] = thresholds->entries[i]; 3517 if (thresholds_new->entries[j].threshold < usage) { 3518 /* 3519 * thresholds_new->current_threshold will not be used 3520 * until rcu_assign_pointer(), so it's safe to increment 3521 * it here. 3522 */ 3523 atomic_inc(&thresholds_new->current_threshold); 3524 } 3525 j++; 3526 } 3527 3528 assign: 3529 if (type == _MEM) 3530 rcu_assign_pointer(memcg->thresholds, thresholds_new); 3531 else 3532 rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new); 3533 3534 /* To be sure that nobody uses thresholds before freeing it */ 3535 synchronize_rcu(); 3536 3537 kfree(thresholds); 3538 unlock: 3539 mutex_unlock(&memcg->thresholds_lock); 3540 3541 return ret; 3542 } 3543 3544 static struct cftype mem_cgroup_files[] = { 3545 { 3546 .name = "usage_in_bytes", 3547 .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), 3548 .read_u64 = mem_cgroup_read, 3549 .register_event = mem_cgroup_register_event, 3550 .unregister_event = mem_cgroup_unregister_event, 3551 }, 3552 { 3553 .name = "max_usage_in_bytes", 3554 .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE), 3555 .trigger = mem_cgroup_reset, 3556 .read_u64 = mem_cgroup_read, 3557 }, 3558 { 3559 .name = "limit_in_bytes", 3560 .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT), 3561 .write_string = mem_cgroup_write, 3562 .read_u64 = mem_cgroup_read, 3563 }, 3564 { 3565 .name = "soft_limit_in_bytes", 3566 .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT), 3567 .write_string = mem_cgroup_write, 3568 .read_u64 = mem_cgroup_read, 3569 }, 3570 { 3571 .name = "failcnt", 3572 .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT), 3573 .trigger = mem_cgroup_reset, 3574 .read_u64 = mem_cgroup_read, 3575 }, 3576 { 3577 .name = "stat", 3578 .read_map = mem_control_stat_show, 3579 }, 3580 { 3581 .name = "force_empty", 3582 .trigger = mem_cgroup_force_empty_write, 3583 }, 3584 { 3585 .name = "use_hierarchy", 3586 .write_u64 = mem_cgroup_hierarchy_write, 3587 .read_u64 = mem_cgroup_hierarchy_read, 3588 }, 3589 { 3590 .name = "swappiness", 3591 .read_u64 = mem_cgroup_swappiness_read, 3592 .write_u64 = mem_cgroup_swappiness_write, 3593 }, 3594 { 3595 .name = "move_charge_at_immigrate", 3596 .read_u64 = mem_cgroup_move_charge_read, 3597 .write_u64 = mem_cgroup_move_charge_write, 3598 }, 3599 }; 3600 3601 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP 3602 static struct cftype memsw_cgroup_files[] = { 3603 { 3604 .name = "memsw.usage_in_bytes", 3605 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), 3606 .read_u64 = mem_cgroup_read, 3607 .register_event = mem_cgroup_register_event, 3608 .unregister_event = mem_cgroup_unregister_event, 3609 }, 3610 { 3611 .name = "memsw.max_usage_in_bytes", 3612 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), 3613 .trigger = mem_cgroup_reset, 3614 .read_u64 = mem_cgroup_read, 3615 }, 3616 { 3617 .name = "memsw.limit_in_bytes", 3618 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), 3619 .write_string = mem_cgroup_write, 3620 .read_u64 = mem_cgroup_read, 3621 }, 3622 { 3623 .name = "memsw.failcnt", 3624 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), 3625 .trigger = mem_cgroup_reset, 3626 .read_u64 = mem_cgroup_read, 3627 }, 3628 }; 3629 3630 static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss) 3631 { 3632 if (!do_swap_account) 3633 return 0; 3634 return cgroup_add_files(cont, ss, memsw_cgroup_files, 3635 ARRAY_SIZE(memsw_cgroup_files)); 3636 }; 3637 #else 3638 static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss) 3639 { 3640 return 0; 3641 } 3642 #endif 3643 3644 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node) 3645 { 3646 struct mem_cgroup_per_node *pn; 3647 struct mem_cgroup_per_zone *mz; 3648 enum lru_list l; 3649 int zone, tmp = node; 3650 /* 3651 * This routine is called against possible nodes. 3652 * But it's BUG to call kmalloc() against offline node. 3653 * 3654 * TODO: this routine can waste much memory for nodes which will 3655 * never be onlined. It's better to use memory hotplug callback 3656 * function. 3657 */ 3658 if (!node_state(node, N_NORMAL_MEMORY)) 3659 tmp = -1; 3660 pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, tmp); 3661 if (!pn) 3662 return 1; 3663 3664 mem->info.nodeinfo[node] = pn; 3665 memset(pn, 0, sizeof(*pn)); 3666 3667 for (zone = 0; zone < MAX_NR_ZONES; zone++) { 3668 mz = &pn->zoneinfo[zone]; 3669 for_each_lru(l) 3670 INIT_LIST_HEAD(&mz->lists[l]); 3671 mz->usage_in_excess = 0; 3672 mz->on_tree = false; 3673 mz->mem = mem; 3674 } 3675 return 0; 3676 } 3677 3678 static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node) 3679 { 3680 kfree(mem->info.nodeinfo[node]); 3681 } 3682 3683 static struct mem_cgroup *mem_cgroup_alloc(void) 3684 { 3685 struct mem_cgroup *mem; 3686 int size = sizeof(struct mem_cgroup); 3687 3688 /* Can be very big if MAX_NUMNODES is very big */ 3689 if (size < PAGE_SIZE) 3690 mem = kmalloc(size, GFP_KERNEL); 3691 else 3692 mem = vmalloc(size); 3693 3694 if (!mem) 3695 return NULL; 3696 3697 memset(mem, 0, size); 3698 mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu); 3699 if (!mem->stat) { 3700 if (size < PAGE_SIZE) 3701 kfree(mem); 3702 else 3703 vfree(mem); 3704 mem = NULL; 3705 } 3706 return mem; 3707 } 3708 3709 /* 3710 * At destroying mem_cgroup, references from swap_cgroup can remain. 3711 * (scanning all at force_empty is too costly...) 3712 * 3713 * Instead of clearing all references at force_empty, we remember 3714 * the number of reference from swap_cgroup and free mem_cgroup when 3715 * it goes down to 0. 3716 * 3717 * Removal of cgroup itself succeeds regardless of refs from swap. 3718 */ 3719 3720 static void __mem_cgroup_free(struct mem_cgroup *mem) 3721 { 3722 int node; 3723 3724 mem_cgroup_remove_from_trees(mem); 3725 free_css_id(&mem_cgroup_subsys, &mem->css); 3726 3727 for_each_node_state(node, N_POSSIBLE) 3728 free_mem_cgroup_per_zone_info(mem, node); 3729 3730 free_percpu(mem->stat); 3731 if (sizeof(struct mem_cgroup) < PAGE_SIZE) 3732 kfree(mem); 3733 else 3734 vfree(mem); 3735 } 3736 3737 static void mem_cgroup_get(struct mem_cgroup *mem) 3738 { 3739 atomic_inc(&mem->refcnt); 3740 } 3741 3742 static void __mem_cgroup_put(struct mem_cgroup *mem, int count) 3743 { 3744 if (atomic_sub_and_test(count, &mem->refcnt)) { 3745 struct mem_cgroup *parent = parent_mem_cgroup(mem); 3746 __mem_cgroup_free(mem); 3747 if (parent) 3748 mem_cgroup_put(parent); 3749 } 3750 } 3751 3752 static void mem_cgroup_put(struct mem_cgroup *mem) 3753 { 3754 __mem_cgroup_put(mem, 1); 3755 } 3756 3757 /* 3758 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled. 3759 */ 3760 static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem) 3761 { 3762 if (!mem->res.parent) 3763 return NULL; 3764 return mem_cgroup_from_res_counter(mem->res.parent, res); 3765 } 3766 3767 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP 3768 static void __init enable_swap_cgroup(void) 3769 { 3770 if (!mem_cgroup_disabled() && really_do_swap_account) 3771 do_swap_account = 1; 3772 } 3773 #else 3774 static void __init enable_swap_cgroup(void) 3775 { 3776 } 3777 #endif 3778 3779 static int mem_cgroup_soft_limit_tree_init(void) 3780 { 3781 struct mem_cgroup_tree_per_node *rtpn; 3782 struct mem_cgroup_tree_per_zone *rtpz; 3783 int tmp, node, zone; 3784 3785 for_each_node_state(node, N_POSSIBLE) { 3786 tmp = node; 3787 if (!node_state(node, N_NORMAL_MEMORY)) 3788 tmp = -1; 3789 rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp); 3790 if (!rtpn) 3791 return 1; 3792 3793 soft_limit_tree.rb_tree_per_node[node] = rtpn; 3794 3795 for (zone = 0; zone < MAX_NR_ZONES; zone++) { 3796 rtpz = &rtpn->rb_tree_per_zone[zone]; 3797 rtpz->rb_root = RB_ROOT; 3798 spin_lock_init(&rtpz->lock); 3799 } 3800 } 3801 return 0; 3802 } 3803 3804 static struct cgroup_subsys_state * __ref 3805 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont) 3806 { 3807 struct mem_cgroup *mem, *parent; 3808 long error = -ENOMEM; 3809 int node; 3810 3811 mem = mem_cgroup_alloc(); 3812 if (!mem) 3813 return ERR_PTR(error); 3814 3815 for_each_node_state(node, N_POSSIBLE) 3816 if (alloc_mem_cgroup_per_zone_info(mem, node)) 3817 goto free_out; 3818 3819 /* root ? */ 3820 if (cont->parent == NULL) { 3821 int cpu; 3822 enable_swap_cgroup(); 3823 parent = NULL; 3824 root_mem_cgroup = mem; 3825 if (mem_cgroup_soft_limit_tree_init()) 3826 goto free_out; 3827 for_each_possible_cpu(cpu) { 3828 struct memcg_stock_pcp *stock = 3829 &per_cpu(memcg_stock, cpu); 3830 INIT_WORK(&stock->work, drain_local_stock); 3831 } 3832 hotcpu_notifier(memcg_stock_cpu_callback, 0); 3833 } else { 3834 parent = mem_cgroup_from_cont(cont->parent); 3835 mem->use_hierarchy = parent->use_hierarchy; 3836 } 3837 3838 if (parent && parent->use_hierarchy) { 3839 res_counter_init(&mem->res, &parent->res); 3840 res_counter_init(&mem->memsw, &parent->memsw); 3841 /* 3842 * We increment refcnt of the parent to ensure that we can 3843 * safely access it on res_counter_charge/uncharge. 3844 * This refcnt will be decremented when freeing this 3845 * mem_cgroup(see mem_cgroup_put). 3846 */ 3847 mem_cgroup_get(parent); 3848 } else { 3849 res_counter_init(&mem->res, NULL); 3850 res_counter_init(&mem->memsw, NULL); 3851 } 3852 mem->last_scanned_child = 0; 3853 spin_lock_init(&mem->reclaim_param_lock); 3854 3855 if (parent) 3856 mem->swappiness = get_swappiness(parent); 3857 atomic_set(&mem->refcnt, 1); 3858 mem->move_charge_at_immigrate = 0; 3859 mutex_init(&mem->thresholds_lock); 3860 return &mem->css; 3861 free_out: 3862 __mem_cgroup_free(mem); 3863 root_mem_cgroup = NULL; 3864 return ERR_PTR(error); 3865 } 3866 3867 static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss, 3868 struct cgroup *cont) 3869 { 3870 struct mem_cgroup *mem = mem_cgroup_from_cont(cont); 3871 3872 return mem_cgroup_force_empty(mem, false); 3873 } 3874 3875 static void mem_cgroup_destroy(struct cgroup_subsys *ss, 3876 struct cgroup *cont) 3877 { 3878 struct mem_cgroup *mem = mem_cgroup_from_cont(cont); 3879 3880 mem_cgroup_put(mem); 3881 } 3882 3883 static int mem_cgroup_populate(struct cgroup_subsys *ss, 3884 struct cgroup *cont) 3885 { 3886 int ret; 3887 3888 ret = cgroup_add_files(cont, ss, mem_cgroup_files, 3889 ARRAY_SIZE(mem_cgroup_files)); 3890 3891 if (!ret) 3892 ret = register_memsw_files(cont, ss); 3893 return ret; 3894 } 3895 3896 #ifdef CONFIG_MMU 3897 /* Handlers for move charge at task migration. */ 3898 #define PRECHARGE_COUNT_AT_ONCE 256 3899 static int mem_cgroup_do_precharge(unsigned long count) 3900 { 3901 int ret = 0; 3902 int batch_count = PRECHARGE_COUNT_AT_ONCE; 3903 struct mem_cgroup *mem = mc.to; 3904 3905 if (mem_cgroup_is_root(mem)) { 3906 mc.precharge += count; 3907 /* we don't need css_get for root */ 3908 return ret; 3909 } 3910 /* try to charge at once */ 3911 if (count > 1) { 3912 struct res_counter *dummy; 3913 /* 3914 * "mem" cannot be under rmdir() because we've already checked 3915 * by cgroup_lock_live_cgroup() that it is not removed and we 3916 * are still under the same cgroup_mutex. So we can postpone 3917 * css_get(). 3918 */ 3919 if (res_counter_charge(&mem->res, PAGE_SIZE * count, &dummy)) 3920 goto one_by_one; 3921 if (do_swap_account && res_counter_charge(&mem->memsw, 3922 PAGE_SIZE * count, &dummy)) { 3923 res_counter_uncharge(&mem->res, PAGE_SIZE * count); 3924 goto one_by_one; 3925 } 3926 mc.precharge += count; 3927 VM_BUG_ON(test_bit(CSS_ROOT, &mem->css.flags)); 3928 WARN_ON_ONCE(count > INT_MAX); 3929 __css_get(&mem->css, (int)count); 3930 return ret; 3931 } 3932 one_by_one: 3933 /* fall back to one by one charge */ 3934 while (count--) { 3935 if (signal_pending(current)) { 3936 ret = -EINTR; 3937 break; 3938 } 3939 if (!batch_count--) { 3940 batch_count = PRECHARGE_COUNT_AT_ONCE; 3941 cond_resched(); 3942 } 3943 ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false); 3944 if (ret || !mem) 3945 /* mem_cgroup_clear_mc() will do uncharge later */ 3946 return -ENOMEM; 3947 mc.precharge++; 3948 } 3949 return ret; 3950 } 3951 3952 /** 3953 * is_target_pte_for_mc - check a pte whether it is valid for move charge 3954 * @vma: the vma the pte to be checked belongs 3955 * @addr: the address corresponding to the pte to be checked 3956 * @ptent: the pte to be checked 3957 * @target: the pointer the target page or swap ent will be stored(can be NULL) 3958 * 3959 * Returns 3960 * 0(MC_TARGET_NONE): if the pte is not a target for move charge. 3961 * 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for 3962 * move charge. if @target is not NULL, the page is stored in target->page 3963 * with extra refcnt got(Callers should handle it). 3964 * 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a 3965 * target for charge migration. if @target is not NULL, the entry is stored 3966 * in target->ent. 3967 * 3968 * Called with pte lock held. 3969 */ 3970 union mc_target { 3971 struct page *page; 3972 swp_entry_t ent; 3973 }; 3974 3975 enum mc_target_type { 3976 MC_TARGET_NONE, /* not used */ 3977 MC_TARGET_PAGE, 3978 MC_TARGET_SWAP, 3979 }; 3980 3981 static int is_target_pte_for_mc(struct vm_area_struct *vma, 3982 unsigned long addr, pte_t ptent, union mc_target *target) 3983 { 3984 struct page *page = NULL; 3985 struct page_cgroup *pc; 3986 int ret = 0; 3987 swp_entry_t ent = { .val = 0 }; 3988 int usage_count = 0; 3989 bool move_anon = test_bit(MOVE_CHARGE_TYPE_ANON, 3990 &mc.to->move_charge_at_immigrate); 3991 3992 if (!pte_present(ptent)) { 3993 /* TODO: handle swap of shmes/tmpfs */ 3994 if (pte_none(ptent) || pte_file(ptent)) 3995 return 0; 3996 else if (is_swap_pte(ptent)) { 3997 ent = pte_to_swp_entry(ptent); 3998 if (!move_anon || non_swap_entry(ent)) 3999 return 0; 4000 usage_count = mem_cgroup_count_swap_user(ent, &page); 4001 } 4002 } else { 4003 page = vm_normal_page(vma, addr, ptent); 4004 if (!page || !page_mapped(page)) 4005 return 0; 4006 /* 4007 * TODO: We don't move charges of file(including shmem/tmpfs) 4008 * pages for now. 4009 */ 4010 if (!move_anon || !PageAnon(page)) 4011 return 0; 4012 if (!get_page_unless_zero(page)) 4013 return 0; 4014 usage_count = page_mapcount(page); 4015 } 4016 if (usage_count > 1) { 4017 /* 4018 * TODO: We don't move charges of shared(used by multiple 4019 * processes) pages for now. 4020 */ 4021 if (page) 4022 put_page(page); 4023 return 0; 4024 } 4025 if (page) { 4026 pc = lookup_page_cgroup(page); 4027 /* 4028 * Do only loose check w/o page_cgroup lock. 4029 * mem_cgroup_move_account() checks the pc is valid or not under 4030 * the lock. 4031 */ 4032 if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) { 4033 ret = MC_TARGET_PAGE; 4034 if (target) 4035 target->page = page; 4036 } 4037 if (!ret || !target) 4038 put_page(page); 4039 } 4040 /* throught */ 4041 if (ent.val && do_swap_account && !ret && 4042 css_id(&mc.from->css) == lookup_swap_cgroup(ent)) { 4043 ret = MC_TARGET_SWAP; 4044 if (target) 4045 target->ent = ent; 4046 } 4047 return ret; 4048 } 4049 4050 static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, 4051 unsigned long addr, unsigned long end, 4052 struct mm_walk *walk) 4053 { 4054 struct vm_area_struct *vma = walk->private; 4055 pte_t *pte; 4056 spinlock_t *ptl; 4057 4058 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 4059 for (; addr != end; pte++, addr += PAGE_SIZE) 4060 if (is_target_pte_for_mc(vma, addr, *pte, NULL)) 4061 mc.precharge++; /* increment precharge temporarily */ 4062 pte_unmap_unlock(pte - 1, ptl); 4063 cond_resched(); 4064 4065 return 0; 4066 } 4067 4068 static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) 4069 { 4070 unsigned long precharge; 4071 struct vm_area_struct *vma; 4072 4073 down_read(&mm->mmap_sem); 4074 for (vma = mm->mmap; vma; vma = vma->vm_next) { 4075 struct mm_walk mem_cgroup_count_precharge_walk = { 4076 .pmd_entry = mem_cgroup_count_precharge_pte_range, 4077 .mm = mm, 4078 .private = vma, 4079 }; 4080 if (is_vm_hugetlb_page(vma)) 4081 continue; 4082 /* TODO: We don't move charges of shmem/tmpfs pages for now. */ 4083 if (vma->vm_flags & VM_SHARED) 4084 continue; 4085 walk_page_range(vma->vm_start, vma->vm_end, 4086 &mem_cgroup_count_precharge_walk); 4087 } 4088 up_read(&mm->mmap_sem); 4089 4090 precharge = mc.precharge; 4091 mc.precharge = 0; 4092 4093 return precharge; 4094 } 4095 4096 static int mem_cgroup_precharge_mc(struct mm_struct *mm) 4097 { 4098 return mem_cgroup_do_precharge(mem_cgroup_count_precharge(mm)); 4099 } 4100 4101 static void mem_cgroup_clear_mc(void) 4102 { 4103 /* we must uncharge all the leftover precharges from mc.to */ 4104 if (mc.precharge) { 4105 __mem_cgroup_cancel_charge(mc.to, mc.precharge); 4106 mc.precharge = 0; 4107 } 4108 /* 4109 * we didn't uncharge from mc.from at mem_cgroup_move_account(), so 4110 * we must uncharge here. 4111 */ 4112 if (mc.moved_charge) { 4113 __mem_cgroup_cancel_charge(mc.from, mc.moved_charge); 4114 mc.moved_charge = 0; 4115 } 4116 /* we must fixup refcnts and charges */ 4117 if (mc.moved_swap) { 4118 WARN_ON_ONCE(mc.moved_swap > INT_MAX); 4119 /* uncharge swap account from the old cgroup */ 4120 if (!mem_cgroup_is_root(mc.from)) 4121 res_counter_uncharge(&mc.from->memsw, 4122 PAGE_SIZE * mc.moved_swap); 4123 __mem_cgroup_put(mc.from, mc.moved_swap); 4124 4125 if (!mem_cgroup_is_root(mc.to)) { 4126 /* 4127 * we charged both to->res and to->memsw, so we should 4128 * uncharge to->res. 4129 */ 4130 res_counter_uncharge(&mc.to->res, 4131 PAGE_SIZE * mc.moved_swap); 4132 VM_BUG_ON(test_bit(CSS_ROOT, &mc.to->css.flags)); 4133 __css_put(&mc.to->css, mc.moved_swap); 4134 } 4135 /* we've already done mem_cgroup_get(mc.to) */ 4136 4137 mc.moved_swap = 0; 4138 } 4139 mc.from = NULL; 4140 mc.to = NULL; 4141 mc.moving_task = NULL; 4142 wake_up_all(&mc.waitq); 4143 } 4144 4145 static int mem_cgroup_can_attach(struct cgroup_subsys *ss, 4146 struct cgroup *cgroup, 4147 struct task_struct *p, 4148 bool threadgroup) 4149 { 4150 int ret = 0; 4151 struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup); 4152 4153 if (mem->move_charge_at_immigrate) { 4154 struct mm_struct *mm; 4155 struct mem_cgroup *from = mem_cgroup_from_task(p); 4156 4157 VM_BUG_ON(from == mem); 4158 4159 mm = get_task_mm(p); 4160 if (!mm) 4161 return 0; 4162 /* We move charges only when we move a owner of the mm */ 4163 if (mm->owner == p) { 4164 VM_BUG_ON(mc.from); 4165 VM_BUG_ON(mc.to); 4166 VM_BUG_ON(mc.precharge); 4167 VM_BUG_ON(mc.moved_charge); 4168 VM_BUG_ON(mc.moved_swap); 4169 VM_BUG_ON(mc.moving_task); 4170 mc.from = from; 4171 mc.to = mem; 4172 mc.precharge = 0; 4173 mc.moved_charge = 0; 4174 mc.moved_swap = 0; 4175 mc.moving_task = current; 4176 4177 ret = mem_cgroup_precharge_mc(mm); 4178 if (ret) 4179 mem_cgroup_clear_mc(); 4180 } 4181 mmput(mm); 4182 } 4183 return ret; 4184 } 4185 4186 static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, 4187 struct cgroup *cgroup, 4188 struct task_struct *p, 4189 bool threadgroup) 4190 { 4191 mem_cgroup_clear_mc(); 4192 } 4193 4194 static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, 4195 unsigned long addr, unsigned long end, 4196 struct mm_walk *walk) 4197 { 4198 int ret = 0; 4199 struct vm_area_struct *vma = walk->private; 4200 pte_t *pte; 4201 spinlock_t *ptl; 4202 4203 retry: 4204 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 4205 for (; addr != end; addr += PAGE_SIZE) { 4206 pte_t ptent = *(pte++); 4207 union mc_target target; 4208 int type; 4209 struct page *page; 4210 struct page_cgroup *pc; 4211 swp_entry_t ent; 4212 4213 if (!mc.precharge) 4214 break; 4215 4216 type = is_target_pte_for_mc(vma, addr, ptent, &target); 4217 switch (type) { 4218 case MC_TARGET_PAGE: 4219 page = target.page; 4220 if (isolate_lru_page(page)) 4221 goto put; 4222 pc = lookup_page_cgroup(page); 4223 if (!mem_cgroup_move_account(pc, 4224 mc.from, mc.to, false)) { 4225 mc.precharge--; 4226 /* we uncharge from mc.from later. */ 4227 mc.moved_charge++; 4228 } 4229 putback_lru_page(page); 4230 put: /* is_target_pte_for_mc() gets the page */ 4231 put_page(page); 4232 break; 4233 case MC_TARGET_SWAP: 4234 ent = target.ent; 4235 if (!mem_cgroup_move_swap_account(ent, 4236 mc.from, mc.to, false)) { 4237 mc.precharge--; 4238 /* we fixup refcnts and charges later. */ 4239 mc.moved_swap++; 4240 } 4241 break; 4242 default: 4243 break; 4244 } 4245 } 4246 pte_unmap_unlock(pte - 1, ptl); 4247 cond_resched(); 4248 4249 if (addr != end) { 4250 /* 4251 * We have consumed all precharges we got in can_attach(). 4252 * We try charge one by one, but don't do any additional 4253 * charges to mc.to if we have failed in charge once in attach() 4254 * phase. 4255 */ 4256 ret = mem_cgroup_do_precharge(1); 4257 if (!ret) 4258 goto retry; 4259 } 4260 4261 return ret; 4262 } 4263 4264 static void mem_cgroup_move_charge(struct mm_struct *mm) 4265 { 4266 struct vm_area_struct *vma; 4267 4268 lru_add_drain_all(); 4269 down_read(&mm->mmap_sem); 4270 for (vma = mm->mmap; vma; vma = vma->vm_next) { 4271 int ret; 4272 struct mm_walk mem_cgroup_move_charge_walk = { 4273 .pmd_entry = mem_cgroup_move_charge_pte_range, 4274 .mm = mm, 4275 .private = vma, 4276 }; 4277 if (is_vm_hugetlb_page(vma)) 4278 continue; 4279 /* TODO: We don't move charges of shmem/tmpfs pages for now. */ 4280 if (vma->vm_flags & VM_SHARED) 4281 continue; 4282 ret = walk_page_range(vma->vm_start, vma->vm_end, 4283 &mem_cgroup_move_charge_walk); 4284 if (ret) 4285 /* 4286 * means we have consumed all precharges and failed in 4287 * doing additional charge. Just abandon here. 4288 */ 4289 break; 4290 } 4291 up_read(&mm->mmap_sem); 4292 } 4293 4294 static void mem_cgroup_move_task(struct cgroup_subsys *ss, 4295 struct cgroup *cont, 4296 struct cgroup *old_cont, 4297 struct task_struct *p, 4298 bool threadgroup) 4299 { 4300 struct mm_struct *mm; 4301 4302 if (!mc.to) 4303 /* no need to move charge */ 4304 return; 4305 4306 mm = get_task_mm(p); 4307 if (mm) { 4308 mem_cgroup_move_charge(mm); 4309 mmput(mm); 4310 } 4311 mem_cgroup_clear_mc(); 4312 } 4313 #else /* !CONFIG_MMU */ 4314 static int mem_cgroup_can_attach(struct cgroup_subsys *ss, 4315 struct cgroup *cgroup, 4316 struct task_struct *p, 4317 bool threadgroup) 4318 { 4319 return 0; 4320 } 4321 static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, 4322 struct cgroup *cgroup, 4323 struct task_struct *p, 4324 bool threadgroup) 4325 { 4326 } 4327 static void mem_cgroup_move_task(struct cgroup_subsys *ss, 4328 struct cgroup *cont, 4329 struct cgroup *old_cont, 4330 struct task_struct *p, 4331 bool threadgroup) 4332 { 4333 } 4334 #endif 4335 4336 struct cgroup_subsys mem_cgroup_subsys = { 4337 .name = "memory", 4338 .subsys_id = mem_cgroup_subsys_id, 4339 .create = mem_cgroup_create, 4340 .pre_destroy = mem_cgroup_pre_destroy, 4341 .destroy = mem_cgroup_destroy, 4342 .populate = mem_cgroup_populate, 4343 .can_attach = mem_cgroup_can_attach, 4344 .cancel_attach = mem_cgroup_cancel_attach, 4345 .attach = mem_cgroup_move_task, 4346 .early_init = 0, 4347 .use_id = 1, 4348 }; 4349 4350 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP 4351 4352 static int __init disable_swap_account(char *s) 4353 { 4354 really_do_swap_account = 0; 4355 return 1; 4356 } 4357 __setup("noswapaccount", disable_swap_account); 4358 #endif 4359