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 * Kernel Memory Controller 14 * Copyright (C) 2012 Parallels Inc. and Google Inc. 15 * Authors: Glauber Costa and Suleiman Souhlal 16 * 17 * This program is free software; you can redistribute it and/or modify 18 * it under the terms of the GNU General Public License as published by 19 * the Free Software Foundation; either version 2 of the License, or 20 * (at your option) any later version. 21 * 22 * This program is distributed in the hope that it will be useful, 23 * but WITHOUT ANY WARRANTY; without even the implied warranty of 24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 25 * GNU General Public License for more details. 26 */ 27 28 #include <linux/res_counter.h> 29 #include <linux/memcontrol.h> 30 #include <linux/cgroup.h> 31 #include <linux/mm.h> 32 #include <linux/hugetlb.h> 33 #include <linux/pagemap.h> 34 #include <linux/smp.h> 35 #include <linux/page-flags.h> 36 #include <linux/backing-dev.h> 37 #include <linux/bit_spinlock.h> 38 #include <linux/rcupdate.h> 39 #include <linux/limits.h> 40 #include <linux/export.h> 41 #include <linux/mutex.h> 42 #include <linux/rbtree.h> 43 #include <linux/slab.h> 44 #include <linux/swap.h> 45 #include <linux/swapops.h> 46 #include <linux/spinlock.h> 47 #include <linux/eventfd.h> 48 #include <linux/poll.h> 49 #include <linux/sort.h> 50 #include <linux/fs.h> 51 #include <linux/seq_file.h> 52 #include <linux/vmpressure.h> 53 #include <linux/mm_inline.h> 54 #include <linux/page_cgroup.h> 55 #include <linux/cpu.h> 56 #include <linux/oom.h> 57 #include <linux/lockdep.h> 58 #include <linux/file.h> 59 #include "internal.h" 60 #include <net/sock.h> 61 #include <net/ip.h> 62 #include <net/tcp_memcontrol.h> 63 #include "slab.h" 64 65 #include <asm/uaccess.h> 66 67 #include <trace/events/vmscan.h> 68 69 struct cgroup_subsys memory_cgrp_subsys __read_mostly; 70 EXPORT_SYMBOL(memory_cgrp_subsys); 71 72 #define MEM_CGROUP_RECLAIM_RETRIES 5 73 static struct mem_cgroup *root_mem_cgroup __read_mostly; 74 75 #ifdef CONFIG_MEMCG_SWAP 76 /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */ 77 int do_swap_account __read_mostly; 78 79 /* for remember boot option*/ 80 #ifdef CONFIG_MEMCG_SWAP_ENABLED 81 static int really_do_swap_account __initdata = 1; 82 #else 83 static int really_do_swap_account __initdata; 84 #endif 85 86 #else 87 #define do_swap_account 0 88 #endif 89 90 91 static const char * const mem_cgroup_stat_names[] = { 92 "cache", 93 "rss", 94 "rss_huge", 95 "mapped_file", 96 "writeback", 97 "swap", 98 }; 99 100 enum mem_cgroup_events_index { 101 MEM_CGROUP_EVENTS_PGPGIN, /* # of pages paged in */ 102 MEM_CGROUP_EVENTS_PGPGOUT, /* # of pages paged out */ 103 MEM_CGROUP_EVENTS_PGFAULT, /* # of page-faults */ 104 MEM_CGROUP_EVENTS_PGMAJFAULT, /* # of major page-faults */ 105 MEM_CGROUP_EVENTS_NSTATS, 106 }; 107 108 static const char * const mem_cgroup_events_names[] = { 109 "pgpgin", 110 "pgpgout", 111 "pgfault", 112 "pgmajfault", 113 }; 114 115 static const char * const mem_cgroup_lru_names[] = { 116 "inactive_anon", 117 "active_anon", 118 "inactive_file", 119 "active_file", 120 "unevictable", 121 }; 122 123 /* 124 * Per memcg event counter is incremented at every pagein/pageout. With THP, 125 * it will be incremated by the number of pages. This counter is used for 126 * for trigger some periodic events. This is straightforward and better 127 * than using jiffies etc. to handle periodic memcg event. 128 */ 129 enum mem_cgroup_events_target { 130 MEM_CGROUP_TARGET_THRESH, 131 MEM_CGROUP_TARGET_SOFTLIMIT, 132 MEM_CGROUP_TARGET_NUMAINFO, 133 MEM_CGROUP_NTARGETS, 134 }; 135 #define THRESHOLDS_EVENTS_TARGET 128 136 #define SOFTLIMIT_EVENTS_TARGET 1024 137 #define NUMAINFO_EVENTS_TARGET 1024 138 139 struct mem_cgroup_stat_cpu { 140 long count[MEM_CGROUP_STAT_NSTATS]; 141 unsigned long events[MEM_CGROUP_EVENTS_NSTATS]; 142 unsigned long nr_page_events; 143 unsigned long targets[MEM_CGROUP_NTARGETS]; 144 }; 145 146 struct mem_cgroup_reclaim_iter { 147 /* 148 * last scanned hierarchy member. Valid only if last_dead_count 149 * matches memcg->dead_count of the hierarchy root group. 150 */ 151 struct mem_cgroup *last_visited; 152 int last_dead_count; 153 154 /* scan generation, increased every round-trip */ 155 unsigned int generation; 156 }; 157 158 /* 159 * per-zone information in memory controller. 160 */ 161 struct mem_cgroup_per_zone { 162 struct lruvec lruvec; 163 unsigned long lru_size[NR_LRU_LISTS]; 164 165 struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1]; 166 167 struct rb_node tree_node; /* RB tree node */ 168 unsigned long long usage_in_excess;/* Set to the value by which */ 169 /* the soft limit is exceeded*/ 170 bool on_tree; 171 struct mem_cgroup *memcg; /* Back pointer, we cannot */ 172 /* use container_of */ 173 }; 174 175 struct mem_cgroup_per_node { 176 struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES]; 177 }; 178 179 /* 180 * Cgroups above their limits are maintained in a RB-Tree, independent of 181 * their hierarchy representation 182 */ 183 184 struct mem_cgroup_tree_per_zone { 185 struct rb_root rb_root; 186 spinlock_t lock; 187 }; 188 189 struct mem_cgroup_tree_per_node { 190 struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES]; 191 }; 192 193 struct mem_cgroup_tree { 194 struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES]; 195 }; 196 197 static struct mem_cgroup_tree soft_limit_tree __read_mostly; 198 199 struct mem_cgroup_threshold { 200 struct eventfd_ctx *eventfd; 201 u64 threshold; 202 }; 203 204 /* For threshold */ 205 struct mem_cgroup_threshold_ary { 206 /* An array index points to threshold just below or equal to usage. */ 207 int current_threshold; 208 /* Size of entries[] */ 209 unsigned int size; 210 /* Array of thresholds */ 211 struct mem_cgroup_threshold entries[0]; 212 }; 213 214 struct mem_cgroup_thresholds { 215 /* Primary thresholds array */ 216 struct mem_cgroup_threshold_ary *primary; 217 /* 218 * Spare threshold array. 219 * This is needed to make mem_cgroup_unregister_event() "never fail". 220 * It must be able to store at least primary->size - 1 entries. 221 */ 222 struct mem_cgroup_threshold_ary *spare; 223 }; 224 225 /* for OOM */ 226 struct mem_cgroup_eventfd_list { 227 struct list_head list; 228 struct eventfd_ctx *eventfd; 229 }; 230 231 /* 232 * cgroup_event represents events which userspace want to receive. 233 */ 234 struct mem_cgroup_event { 235 /* 236 * memcg which the event belongs to. 237 */ 238 struct mem_cgroup *memcg; 239 /* 240 * eventfd to signal userspace about the event. 241 */ 242 struct eventfd_ctx *eventfd; 243 /* 244 * Each of these stored in a list by the cgroup. 245 */ 246 struct list_head list; 247 /* 248 * register_event() callback will be used to add new userspace 249 * waiter for changes related to this event. Use eventfd_signal() 250 * on eventfd to send notification to userspace. 251 */ 252 int (*register_event)(struct mem_cgroup *memcg, 253 struct eventfd_ctx *eventfd, const char *args); 254 /* 255 * unregister_event() callback will be called when userspace closes 256 * the eventfd or on cgroup removing. This callback must be set, 257 * if you want provide notification functionality. 258 */ 259 void (*unregister_event)(struct mem_cgroup *memcg, 260 struct eventfd_ctx *eventfd); 261 /* 262 * All fields below needed to unregister event when 263 * userspace closes eventfd. 264 */ 265 poll_table pt; 266 wait_queue_head_t *wqh; 267 wait_queue_t wait; 268 struct work_struct remove; 269 }; 270 271 static void mem_cgroup_threshold(struct mem_cgroup *memcg); 272 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); 273 274 /* 275 * The memory controller data structure. The memory controller controls both 276 * page cache and RSS per cgroup. We would eventually like to provide 277 * statistics based on the statistics developed by Rik Van Riel for clock-pro, 278 * to help the administrator determine what knobs to tune. 279 * 280 * TODO: Add a water mark for the memory controller. Reclaim will begin when 281 * we hit the water mark. May be even add a low water mark, such that 282 * no reclaim occurs from a cgroup at it's low water mark, this is 283 * a feature that will be implemented much later in the future. 284 */ 285 struct mem_cgroup { 286 struct cgroup_subsys_state css; 287 /* 288 * the counter to account for memory usage 289 */ 290 struct res_counter res; 291 292 /* vmpressure notifications */ 293 struct vmpressure vmpressure; 294 295 /* 296 * the counter to account for mem+swap usage. 297 */ 298 struct res_counter memsw; 299 300 /* 301 * the counter to account for kernel memory usage. 302 */ 303 struct res_counter kmem; 304 /* 305 * Should the accounting and control be hierarchical, per subtree? 306 */ 307 bool use_hierarchy; 308 unsigned long kmem_account_flags; /* See KMEM_ACCOUNTED_*, below */ 309 310 bool oom_lock; 311 atomic_t under_oom; 312 atomic_t oom_wakeups; 313 314 int swappiness; 315 /* OOM-Killer disable */ 316 int oom_kill_disable; 317 318 /* set when res.limit == memsw.limit */ 319 bool memsw_is_minimum; 320 321 /* protect arrays of thresholds */ 322 struct mutex thresholds_lock; 323 324 /* thresholds for memory usage. RCU-protected */ 325 struct mem_cgroup_thresholds thresholds; 326 327 /* thresholds for mem+swap usage. RCU-protected */ 328 struct mem_cgroup_thresholds memsw_thresholds; 329 330 /* For oom notifier event fd */ 331 struct list_head oom_notify; 332 333 /* 334 * Should we move charges of a task when a task is moved into this 335 * mem_cgroup ? And what type of charges should we move ? 336 */ 337 unsigned long move_charge_at_immigrate; 338 /* 339 * set > 0 if pages under this cgroup are moving to other cgroup. 340 */ 341 atomic_t moving_account; 342 /* taken only while moving_account > 0 */ 343 spinlock_t move_lock; 344 /* 345 * percpu counter. 346 */ 347 struct mem_cgroup_stat_cpu __percpu *stat; 348 /* 349 * used when a cpu is offlined or other synchronizations 350 * See mem_cgroup_read_stat(). 351 */ 352 struct mem_cgroup_stat_cpu nocpu_base; 353 spinlock_t pcp_counter_lock; 354 355 atomic_t dead_count; 356 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET) 357 struct cg_proto tcp_mem; 358 #endif 359 #if defined(CONFIG_MEMCG_KMEM) 360 /* analogous to slab_common's slab_caches list, but per-memcg; 361 * protected by memcg_slab_mutex */ 362 struct list_head memcg_slab_caches; 363 /* Index in the kmem_cache->memcg_params->memcg_caches array */ 364 int kmemcg_id; 365 #endif 366 367 int last_scanned_node; 368 #if MAX_NUMNODES > 1 369 nodemask_t scan_nodes; 370 atomic_t numainfo_events; 371 atomic_t numainfo_updating; 372 #endif 373 374 /* List of events which userspace want to receive */ 375 struct list_head event_list; 376 spinlock_t event_list_lock; 377 378 struct mem_cgroup_per_node *nodeinfo[0]; 379 /* WARNING: nodeinfo must be the last member here */ 380 }; 381 382 /* internal only representation about the status of kmem accounting. */ 383 enum { 384 KMEM_ACCOUNTED_ACTIVE, /* accounted by this cgroup itself */ 385 KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */ 386 }; 387 388 #ifdef CONFIG_MEMCG_KMEM 389 static inline void memcg_kmem_set_active(struct mem_cgroup *memcg) 390 { 391 set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); 392 } 393 394 static bool memcg_kmem_is_active(struct mem_cgroup *memcg) 395 { 396 return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); 397 } 398 399 static void memcg_kmem_mark_dead(struct mem_cgroup *memcg) 400 { 401 /* 402 * Our caller must use css_get() first, because memcg_uncharge_kmem() 403 * will call css_put() if it sees the memcg is dead. 404 */ 405 smp_wmb(); 406 if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags)) 407 set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags); 408 } 409 410 static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg) 411 { 412 return test_and_clear_bit(KMEM_ACCOUNTED_DEAD, 413 &memcg->kmem_account_flags); 414 } 415 #endif 416 417 /* Stuffs for move charges at task migration. */ 418 /* 419 * Types of charges to be moved. "move_charge_at_immitgrate" and 420 * "immigrate_flags" are treated as a left-shifted bitmap of these types. 421 */ 422 enum move_type { 423 MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */ 424 MOVE_CHARGE_TYPE_FILE, /* file page(including tmpfs) and swap of it */ 425 NR_MOVE_TYPE, 426 }; 427 428 /* "mc" and its members are protected by cgroup_mutex */ 429 static struct move_charge_struct { 430 spinlock_t lock; /* for from, to */ 431 struct mem_cgroup *from; 432 struct mem_cgroup *to; 433 unsigned long immigrate_flags; 434 unsigned long precharge; 435 unsigned long moved_charge; 436 unsigned long moved_swap; 437 struct task_struct *moving_task; /* a task moving charges */ 438 wait_queue_head_t waitq; /* a waitq for other context */ 439 } mc = { 440 .lock = __SPIN_LOCK_UNLOCKED(mc.lock), 441 .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), 442 }; 443 444 static bool move_anon(void) 445 { 446 return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags); 447 } 448 449 static bool move_file(void) 450 { 451 return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags); 452 } 453 454 /* 455 * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft 456 * limit reclaim to prevent infinite loops, if they ever occur. 457 */ 458 #define MEM_CGROUP_MAX_RECLAIM_LOOPS 100 459 #define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2 460 461 enum charge_type { 462 MEM_CGROUP_CHARGE_TYPE_CACHE = 0, 463 MEM_CGROUP_CHARGE_TYPE_ANON, 464 MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */ 465 MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */ 466 NR_CHARGE_TYPE, 467 }; 468 469 /* for encoding cft->private value on file */ 470 enum res_type { 471 _MEM, 472 _MEMSWAP, 473 _OOM_TYPE, 474 _KMEM, 475 }; 476 477 #define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val)) 478 #define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff) 479 #define MEMFILE_ATTR(val) ((val) & 0xffff) 480 /* Used for OOM nofiier */ 481 #define OOM_CONTROL (0) 482 483 /* 484 * Reclaim flags for mem_cgroup_hierarchical_reclaim 485 */ 486 #define MEM_CGROUP_RECLAIM_NOSWAP_BIT 0x0 487 #define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT) 488 #define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1 489 #define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT) 490 491 /* 492 * The memcg_create_mutex will be held whenever a new cgroup is created. 493 * As a consequence, any change that needs to protect against new child cgroups 494 * appearing has to hold it as well. 495 */ 496 static DEFINE_MUTEX(memcg_create_mutex); 497 498 struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s) 499 { 500 return s ? container_of(s, struct mem_cgroup, css) : NULL; 501 } 502 503 /* Some nice accessors for the vmpressure. */ 504 struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg) 505 { 506 if (!memcg) 507 memcg = root_mem_cgroup; 508 return &memcg->vmpressure; 509 } 510 511 struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr) 512 { 513 return &container_of(vmpr, struct mem_cgroup, vmpressure)->css; 514 } 515 516 static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) 517 { 518 return (memcg == root_mem_cgroup); 519 } 520 521 /* 522 * We restrict the id in the range of [1, 65535], so it can fit into 523 * an unsigned short. 524 */ 525 #define MEM_CGROUP_ID_MAX USHRT_MAX 526 527 static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg) 528 { 529 /* 530 * The ID of the root cgroup is 0, but memcg treat 0 as an 531 * invalid ID, so we return (cgroup_id + 1). 532 */ 533 return memcg->css.cgroup->id + 1; 534 } 535 536 static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id) 537 { 538 struct cgroup_subsys_state *css; 539 540 css = css_from_id(id - 1, &memory_cgrp_subsys); 541 return mem_cgroup_from_css(css); 542 } 543 544 /* Writing them here to avoid exposing memcg's inner layout */ 545 #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM) 546 547 void sock_update_memcg(struct sock *sk) 548 { 549 if (mem_cgroup_sockets_enabled) { 550 struct mem_cgroup *memcg; 551 struct cg_proto *cg_proto; 552 553 BUG_ON(!sk->sk_prot->proto_cgroup); 554 555 /* Socket cloning can throw us here with sk_cgrp already 556 * filled. It won't however, necessarily happen from 557 * process context. So the test for root memcg given 558 * the current task's memcg won't help us in this case. 559 * 560 * Respecting the original socket's memcg is a better 561 * decision in this case. 562 */ 563 if (sk->sk_cgrp) { 564 BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg)); 565 css_get(&sk->sk_cgrp->memcg->css); 566 return; 567 } 568 569 rcu_read_lock(); 570 memcg = mem_cgroup_from_task(current); 571 cg_proto = sk->sk_prot->proto_cgroup(memcg); 572 if (!mem_cgroup_is_root(memcg) && 573 memcg_proto_active(cg_proto) && css_tryget(&memcg->css)) { 574 sk->sk_cgrp = cg_proto; 575 } 576 rcu_read_unlock(); 577 } 578 } 579 EXPORT_SYMBOL(sock_update_memcg); 580 581 void sock_release_memcg(struct sock *sk) 582 { 583 if (mem_cgroup_sockets_enabled && sk->sk_cgrp) { 584 struct mem_cgroup *memcg; 585 WARN_ON(!sk->sk_cgrp->memcg); 586 memcg = sk->sk_cgrp->memcg; 587 css_put(&sk->sk_cgrp->memcg->css); 588 } 589 } 590 591 struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg) 592 { 593 if (!memcg || mem_cgroup_is_root(memcg)) 594 return NULL; 595 596 return &memcg->tcp_mem; 597 } 598 EXPORT_SYMBOL(tcp_proto_cgroup); 599 600 static void disarm_sock_keys(struct mem_cgroup *memcg) 601 { 602 if (!memcg_proto_activated(&memcg->tcp_mem)) 603 return; 604 static_key_slow_dec(&memcg_socket_limit_enabled); 605 } 606 #else 607 static void disarm_sock_keys(struct mem_cgroup *memcg) 608 { 609 } 610 #endif 611 612 #ifdef CONFIG_MEMCG_KMEM 613 /* 614 * This will be the memcg's index in each cache's ->memcg_params->memcg_caches. 615 * The main reason for not using cgroup id for this: 616 * this works better in sparse environments, where we have a lot of memcgs, 617 * but only a few kmem-limited. Or also, if we have, for instance, 200 618 * memcgs, and none but the 200th is kmem-limited, we'd have to have a 619 * 200 entry array for that. 620 * 621 * The current size of the caches array is stored in 622 * memcg_limited_groups_array_size. It will double each time we have to 623 * increase it. 624 */ 625 static DEFINE_IDA(kmem_limited_groups); 626 int memcg_limited_groups_array_size; 627 628 /* 629 * MIN_SIZE is different than 1, because we would like to avoid going through 630 * the alloc/free process all the time. In a small machine, 4 kmem-limited 631 * cgroups is a reasonable guess. In the future, it could be a parameter or 632 * tunable, but that is strictly not necessary. 633 * 634 * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get 635 * this constant directly from cgroup, but it is understandable that this is 636 * better kept as an internal representation in cgroup.c. In any case, the 637 * cgrp_id space is not getting any smaller, and we don't have to necessarily 638 * increase ours as well if it increases. 639 */ 640 #define MEMCG_CACHES_MIN_SIZE 4 641 #define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX 642 643 /* 644 * A lot of the calls to the cache allocation functions are expected to be 645 * inlined by the compiler. Since the calls to memcg_kmem_get_cache are 646 * conditional to this static branch, we'll have to allow modules that does 647 * kmem_cache_alloc and the such to see this symbol as well 648 */ 649 struct static_key memcg_kmem_enabled_key; 650 EXPORT_SYMBOL(memcg_kmem_enabled_key); 651 652 static void disarm_kmem_keys(struct mem_cgroup *memcg) 653 { 654 if (memcg_kmem_is_active(memcg)) { 655 static_key_slow_dec(&memcg_kmem_enabled_key); 656 ida_simple_remove(&kmem_limited_groups, memcg->kmemcg_id); 657 } 658 /* 659 * This check can't live in kmem destruction function, 660 * since the charges will outlive the cgroup 661 */ 662 WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0); 663 } 664 #else 665 static void disarm_kmem_keys(struct mem_cgroup *memcg) 666 { 667 } 668 #endif /* CONFIG_MEMCG_KMEM */ 669 670 static void disarm_static_keys(struct mem_cgroup *memcg) 671 { 672 disarm_sock_keys(memcg); 673 disarm_kmem_keys(memcg); 674 } 675 676 static void drain_all_stock_async(struct mem_cgroup *memcg); 677 678 static struct mem_cgroup_per_zone * 679 mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid) 680 { 681 VM_BUG_ON((unsigned)nid >= nr_node_ids); 682 return &memcg->nodeinfo[nid]->zoneinfo[zid]; 683 } 684 685 struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg) 686 { 687 return &memcg->css; 688 } 689 690 static struct mem_cgroup_per_zone * 691 page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page) 692 { 693 int nid = page_to_nid(page); 694 int zid = page_zonenum(page); 695 696 return mem_cgroup_zoneinfo(memcg, nid, zid); 697 } 698 699 static struct mem_cgroup_tree_per_zone * 700 soft_limit_tree_node_zone(int nid, int zid) 701 { 702 return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid]; 703 } 704 705 static struct mem_cgroup_tree_per_zone * 706 soft_limit_tree_from_page(struct page *page) 707 { 708 int nid = page_to_nid(page); 709 int zid = page_zonenum(page); 710 711 return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid]; 712 } 713 714 static void 715 __mem_cgroup_insert_exceeded(struct mem_cgroup *memcg, 716 struct mem_cgroup_per_zone *mz, 717 struct mem_cgroup_tree_per_zone *mctz, 718 unsigned long long new_usage_in_excess) 719 { 720 struct rb_node **p = &mctz->rb_root.rb_node; 721 struct rb_node *parent = NULL; 722 struct mem_cgroup_per_zone *mz_node; 723 724 if (mz->on_tree) 725 return; 726 727 mz->usage_in_excess = new_usage_in_excess; 728 if (!mz->usage_in_excess) 729 return; 730 while (*p) { 731 parent = *p; 732 mz_node = rb_entry(parent, struct mem_cgroup_per_zone, 733 tree_node); 734 if (mz->usage_in_excess < mz_node->usage_in_excess) 735 p = &(*p)->rb_left; 736 /* 737 * We can't avoid mem cgroups that are over their soft 738 * limit by the same amount 739 */ 740 else if (mz->usage_in_excess >= mz_node->usage_in_excess) 741 p = &(*p)->rb_right; 742 } 743 rb_link_node(&mz->tree_node, parent, p); 744 rb_insert_color(&mz->tree_node, &mctz->rb_root); 745 mz->on_tree = true; 746 } 747 748 static void 749 __mem_cgroup_remove_exceeded(struct mem_cgroup *memcg, 750 struct mem_cgroup_per_zone *mz, 751 struct mem_cgroup_tree_per_zone *mctz) 752 { 753 if (!mz->on_tree) 754 return; 755 rb_erase(&mz->tree_node, &mctz->rb_root); 756 mz->on_tree = false; 757 } 758 759 static void 760 mem_cgroup_remove_exceeded(struct mem_cgroup *memcg, 761 struct mem_cgroup_per_zone *mz, 762 struct mem_cgroup_tree_per_zone *mctz) 763 { 764 spin_lock(&mctz->lock); 765 __mem_cgroup_remove_exceeded(memcg, mz, mctz); 766 spin_unlock(&mctz->lock); 767 } 768 769 770 static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page) 771 { 772 unsigned long long excess; 773 struct mem_cgroup_per_zone *mz; 774 struct mem_cgroup_tree_per_zone *mctz; 775 int nid = page_to_nid(page); 776 int zid = page_zonenum(page); 777 mctz = soft_limit_tree_from_page(page); 778 779 /* 780 * Necessary to update all ancestors when hierarchy is used. 781 * because their event counter is not touched. 782 */ 783 for (; memcg; memcg = parent_mem_cgroup(memcg)) { 784 mz = mem_cgroup_zoneinfo(memcg, nid, zid); 785 excess = res_counter_soft_limit_excess(&memcg->res); 786 /* 787 * We have to update the tree if mz is on RB-tree or 788 * mem is over its softlimit. 789 */ 790 if (excess || mz->on_tree) { 791 spin_lock(&mctz->lock); 792 /* if on-tree, remove it */ 793 if (mz->on_tree) 794 __mem_cgroup_remove_exceeded(memcg, mz, mctz); 795 /* 796 * Insert again. mz->usage_in_excess will be updated. 797 * If excess is 0, no tree ops. 798 */ 799 __mem_cgroup_insert_exceeded(memcg, mz, mctz, excess); 800 spin_unlock(&mctz->lock); 801 } 802 } 803 } 804 805 static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) 806 { 807 int node, zone; 808 struct mem_cgroup_per_zone *mz; 809 struct mem_cgroup_tree_per_zone *mctz; 810 811 for_each_node(node) { 812 for (zone = 0; zone < MAX_NR_ZONES; zone++) { 813 mz = mem_cgroup_zoneinfo(memcg, node, zone); 814 mctz = soft_limit_tree_node_zone(node, zone); 815 mem_cgroup_remove_exceeded(memcg, mz, mctz); 816 } 817 } 818 } 819 820 static struct mem_cgroup_per_zone * 821 __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz) 822 { 823 struct rb_node *rightmost = NULL; 824 struct mem_cgroup_per_zone *mz; 825 826 retry: 827 mz = NULL; 828 rightmost = rb_last(&mctz->rb_root); 829 if (!rightmost) 830 goto done; /* Nothing to reclaim from */ 831 832 mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node); 833 /* 834 * Remove the node now but someone else can add it back, 835 * we will to add it back at the end of reclaim to its correct 836 * position in the tree. 837 */ 838 __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz); 839 if (!res_counter_soft_limit_excess(&mz->memcg->res) || 840 !css_tryget(&mz->memcg->css)) 841 goto retry; 842 done: 843 return mz; 844 } 845 846 static struct mem_cgroup_per_zone * 847 mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz) 848 { 849 struct mem_cgroup_per_zone *mz; 850 851 spin_lock(&mctz->lock); 852 mz = __mem_cgroup_largest_soft_limit_node(mctz); 853 spin_unlock(&mctz->lock); 854 return mz; 855 } 856 857 /* 858 * Implementation Note: reading percpu statistics for memcg. 859 * 860 * Both of vmstat[] and percpu_counter has threshold and do periodic 861 * synchronization to implement "quick" read. There are trade-off between 862 * reading cost and precision of value. Then, we may have a chance to implement 863 * a periodic synchronizion of counter in memcg's counter. 864 * 865 * But this _read() function is used for user interface now. The user accounts 866 * memory usage by memory cgroup and he _always_ requires exact value because 867 * he accounts memory. Even if we provide quick-and-fuzzy read, we always 868 * have to visit all online cpus and make sum. So, for now, unnecessary 869 * synchronization is not implemented. (just implemented for cpu hotplug) 870 * 871 * If there are kernel internal actions which can make use of some not-exact 872 * value, and reading all cpu value can be performance bottleneck in some 873 * common workload, threashold and synchonization as vmstat[] should be 874 * implemented. 875 */ 876 static long mem_cgroup_read_stat(struct mem_cgroup *memcg, 877 enum mem_cgroup_stat_index idx) 878 { 879 long val = 0; 880 int cpu; 881 882 get_online_cpus(); 883 for_each_online_cpu(cpu) 884 val += per_cpu(memcg->stat->count[idx], cpu); 885 #ifdef CONFIG_HOTPLUG_CPU 886 spin_lock(&memcg->pcp_counter_lock); 887 val += memcg->nocpu_base.count[idx]; 888 spin_unlock(&memcg->pcp_counter_lock); 889 #endif 890 put_online_cpus(); 891 return val; 892 } 893 894 static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg, 895 bool charge) 896 { 897 int val = (charge) ? 1 : -1; 898 this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val); 899 } 900 901 static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg, 902 enum mem_cgroup_events_index idx) 903 { 904 unsigned long val = 0; 905 int cpu; 906 907 get_online_cpus(); 908 for_each_online_cpu(cpu) 909 val += per_cpu(memcg->stat->events[idx], cpu); 910 #ifdef CONFIG_HOTPLUG_CPU 911 spin_lock(&memcg->pcp_counter_lock); 912 val += memcg->nocpu_base.events[idx]; 913 spin_unlock(&memcg->pcp_counter_lock); 914 #endif 915 put_online_cpus(); 916 return val; 917 } 918 919 static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, 920 struct page *page, 921 bool anon, int nr_pages) 922 { 923 /* 924 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is 925 * counted as CACHE even if it's on ANON LRU. 926 */ 927 if (anon) 928 __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS], 929 nr_pages); 930 else 931 __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE], 932 nr_pages); 933 934 if (PageTransHuge(page)) 935 __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], 936 nr_pages); 937 938 /* pagein of a big page is an event. So, ignore page size */ 939 if (nr_pages > 0) 940 __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]); 941 else { 942 __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]); 943 nr_pages = -nr_pages; /* for event */ 944 } 945 946 __this_cpu_add(memcg->stat->nr_page_events, nr_pages); 947 } 948 949 unsigned long 950 mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru) 951 { 952 struct mem_cgroup_per_zone *mz; 953 954 mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec); 955 return mz->lru_size[lru]; 956 } 957 958 static unsigned long 959 mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid, 960 unsigned int lru_mask) 961 { 962 struct mem_cgroup_per_zone *mz; 963 enum lru_list lru; 964 unsigned long ret = 0; 965 966 mz = mem_cgroup_zoneinfo(memcg, nid, zid); 967 968 for_each_lru(lru) { 969 if (BIT(lru) & lru_mask) 970 ret += mz->lru_size[lru]; 971 } 972 return ret; 973 } 974 975 static unsigned long 976 mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, 977 int nid, unsigned int lru_mask) 978 { 979 u64 total = 0; 980 int zid; 981 982 for (zid = 0; zid < MAX_NR_ZONES; zid++) 983 total += mem_cgroup_zone_nr_lru_pages(memcg, 984 nid, zid, lru_mask); 985 986 return total; 987 } 988 989 static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg, 990 unsigned int lru_mask) 991 { 992 int nid; 993 u64 total = 0; 994 995 for_each_node_state(nid, N_MEMORY) 996 total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask); 997 return total; 998 } 999 1000 static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, 1001 enum mem_cgroup_events_target target) 1002 { 1003 unsigned long val, next; 1004 1005 val = __this_cpu_read(memcg->stat->nr_page_events); 1006 next = __this_cpu_read(memcg->stat->targets[target]); 1007 /* from time_after() in jiffies.h */ 1008 if ((long)next - (long)val < 0) { 1009 switch (target) { 1010 case MEM_CGROUP_TARGET_THRESH: 1011 next = val + THRESHOLDS_EVENTS_TARGET; 1012 break; 1013 case MEM_CGROUP_TARGET_SOFTLIMIT: 1014 next = val + SOFTLIMIT_EVENTS_TARGET; 1015 break; 1016 case MEM_CGROUP_TARGET_NUMAINFO: 1017 next = val + NUMAINFO_EVENTS_TARGET; 1018 break; 1019 default: 1020 break; 1021 } 1022 __this_cpu_write(memcg->stat->targets[target], next); 1023 return true; 1024 } 1025 return false; 1026 } 1027 1028 /* 1029 * Check events in order. 1030 * 1031 */ 1032 static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) 1033 { 1034 preempt_disable(); 1035 /* threshold event is triggered in finer grain than soft limit */ 1036 if (unlikely(mem_cgroup_event_ratelimit(memcg, 1037 MEM_CGROUP_TARGET_THRESH))) { 1038 bool do_softlimit; 1039 bool do_numainfo __maybe_unused; 1040 1041 do_softlimit = mem_cgroup_event_ratelimit(memcg, 1042 MEM_CGROUP_TARGET_SOFTLIMIT); 1043 #if MAX_NUMNODES > 1 1044 do_numainfo = mem_cgroup_event_ratelimit(memcg, 1045 MEM_CGROUP_TARGET_NUMAINFO); 1046 #endif 1047 preempt_enable(); 1048 1049 mem_cgroup_threshold(memcg); 1050 if (unlikely(do_softlimit)) 1051 mem_cgroup_update_tree(memcg, page); 1052 #if MAX_NUMNODES > 1 1053 if (unlikely(do_numainfo)) 1054 atomic_inc(&memcg->numainfo_events); 1055 #endif 1056 } else 1057 preempt_enable(); 1058 } 1059 1060 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) 1061 { 1062 /* 1063 * mm_update_next_owner() may clear mm->owner to NULL 1064 * if it races with swapoff, page migration, etc. 1065 * So this can be called with p == NULL. 1066 */ 1067 if (unlikely(!p)) 1068 return NULL; 1069 1070 return mem_cgroup_from_css(task_css(p, memory_cgrp_id)); 1071 } 1072 1073 static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) 1074 { 1075 struct mem_cgroup *memcg = NULL; 1076 1077 rcu_read_lock(); 1078 do { 1079 /* 1080 * Page cache insertions can happen withou an 1081 * actual mm context, e.g. during disk probing 1082 * on boot, loopback IO, acct() writes etc. 1083 */ 1084 if (unlikely(!mm)) 1085 memcg = root_mem_cgroup; 1086 else { 1087 memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); 1088 if (unlikely(!memcg)) 1089 memcg = root_mem_cgroup; 1090 } 1091 } while (!css_tryget(&memcg->css)); 1092 rcu_read_unlock(); 1093 return memcg; 1094 } 1095 1096 /* 1097 * Returns a next (in a pre-order walk) alive memcg (with elevated css 1098 * ref. count) or NULL if the whole root's subtree has been visited. 1099 * 1100 * helper function to be used by mem_cgroup_iter 1101 */ 1102 static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root, 1103 struct mem_cgroup *last_visited) 1104 { 1105 struct cgroup_subsys_state *prev_css, *next_css; 1106 1107 prev_css = last_visited ? &last_visited->css : NULL; 1108 skip_node: 1109 next_css = css_next_descendant_pre(prev_css, &root->css); 1110 1111 /* 1112 * Even if we found a group we have to make sure it is 1113 * alive. css && !memcg means that the groups should be 1114 * skipped and we should continue the tree walk. 1115 * last_visited css is safe to use because it is 1116 * protected by css_get and the tree walk is rcu safe. 1117 * 1118 * We do not take a reference on the root of the tree walk 1119 * because we might race with the root removal when it would 1120 * be the only node in the iterated hierarchy and mem_cgroup_iter 1121 * would end up in an endless loop because it expects that at 1122 * least one valid node will be returned. Root cannot disappear 1123 * because caller of the iterator should hold it already so 1124 * skipping css reference should be safe. 1125 */ 1126 if (next_css) { 1127 if ((next_css == &root->css) || 1128 ((next_css->flags & CSS_ONLINE) && css_tryget(next_css))) 1129 return mem_cgroup_from_css(next_css); 1130 1131 prev_css = next_css; 1132 goto skip_node; 1133 } 1134 1135 return NULL; 1136 } 1137 1138 static void mem_cgroup_iter_invalidate(struct mem_cgroup *root) 1139 { 1140 /* 1141 * When a group in the hierarchy below root is destroyed, the 1142 * hierarchy iterator can no longer be trusted since it might 1143 * have pointed to the destroyed group. Invalidate it. 1144 */ 1145 atomic_inc(&root->dead_count); 1146 } 1147 1148 static struct mem_cgroup * 1149 mem_cgroup_iter_load(struct mem_cgroup_reclaim_iter *iter, 1150 struct mem_cgroup *root, 1151 int *sequence) 1152 { 1153 struct mem_cgroup *position = NULL; 1154 /* 1155 * A cgroup destruction happens in two stages: offlining and 1156 * release. They are separated by a RCU grace period. 1157 * 1158 * If the iterator is valid, we may still race with an 1159 * offlining. The RCU lock ensures the object won't be 1160 * released, tryget will fail if we lost the race. 1161 */ 1162 *sequence = atomic_read(&root->dead_count); 1163 if (iter->last_dead_count == *sequence) { 1164 smp_rmb(); 1165 position = iter->last_visited; 1166 1167 /* 1168 * We cannot take a reference to root because we might race 1169 * with root removal and returning NULL would end up in 1170 * an endless loop on the iterator user level when root 1171 * would be returned all the time. 1172 */ 1173 if (position && position != root && 1174 !css_tryget(&position->css)) 1175 position = NULL; 1176 } 1177 return position; 1178 } 1179 1180 static void mem_cgroup_iter_update(struct mem_cgroup_reclaim_iter *iter, 1181 struct mem_cgroup *last_visited, 1182 struct mem_cgroup *new_position, 1183 struct mem_cgroup *root, 1184 int sequence) 1185 { 1186 /* root reference counting symmetric to mem_cgroup_iter_load */ 1187 if (last_visited && last_visited != root) 1188 css_put(&last_visited->css); 1189 /* 1190 * We store the sequence count from the time @last_visited was 1191 * loaded successfully instead of rereading it here so that we 1192 * don't lose destruction events in between. We could have 1193 * raced with the destruction of @new_position after all. 1194 */ 1195 iter->last_visited = new_position; 1196 smp_wmb(); 1197 iter->last_dead_count = sequence; 1198 } 1199 1200 /** 1201 * mem_cgroup_iter - iterate over memory cgroup hierarchy 1202 * @root: hierarchy root 1203 * @prev: previously returned memcg, NULL on first invocation 1204 * @reclaim: cookie for shared reclaim walks, NULL for full walks 1205 * 1206 * Returns references to children of the hierarchy below @root, or 1207 * @root itself, or %NULL after a full round-trip. 1208 * 1209 * Caller must pass the return value in @prev on subsequent 1210 * invocations for reference counting, or use mem_cgroup_iter_break() 1211 * to cancel a hierarchy walk before the round-trip is complete. 1212 * 1213 * Reclaimers can specify a zone and a priority level in @reclaim to 1214 * divide up the memcgs in the hierarchy among all concurrent 1215 * reclaimers operating on the same zone and priority. 1216 */ 1217 struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, 1218 struct mem_cgroup *prev, 1219 struct mem_cgroup_reclaim_cookie *reclaim) 1220 { 1221 struct mem_cgroup *memcg = NULL; 1222 struct mem_cgroup *last_visited = NULL; 1223 1224 if (mem_cgroup_disabled()) 1225 return NULL; 1226 1227 if (!root) 1228 root = root_mem_cgroup; 1229 1230 if (prev && !reclaim) 1231 last_visited = prev; 1232 1233 if (!root->use_hierarchy && root != root_mem_cgroup) { 1234 if (prev) 1235 goto out_css_put; 1236 return root; 1237 } 1238 1239 rcu_read_lock(); 1240 while (!memcg) { 1241 struct mem_cgroup_reclaim_iter *uninitialized_var(iter); 1242 int uninitialized_var(seq); 1243 1244 if (reclaim) { 1245 int nid = zone_to_nid(reclaim->zone); 1246 int zid = zone_idx(reclaim->zone); 1247 struct mem_cgroup_per_zone *mz; 1248 1249 mz = mem_cgroup_zoneinfo(root, nid, zid); 1250 iter = &mz->reclaim_iter[reclaim->priority]; 1251 if (prev && reclaim->generation != iter->generation) { 1252 iter->last_visited = NULL; 1253 goto out_unlock; 1254 } 1255 1256 last_visited = mem_cgroup_iter_load(iter, root, &seq); 1257 } 1258 1259 memcg = __mem_cgroup_iter_next(root, last_visited); 1260 1261 if (reclaim) { 1262 mem_cgroup_iter_update(iter, last_visited, memcg, root, 1263 seq); 1264 1265 if (!memcg) 1266 iter->generation++; 1267 else if (!prev && memcg) 1268 reclaim->generation = iter->generation; 1269 } 1270 1271 if (prev && !memcg) 1272 goto out_unlock; 1273 } 1274 out_unlock: 1275 rcu_read_unlock(); 1276 out_css_put: 1277 if (prev && prev != root) 1278 css_put(&prev->css); 1279 1280 return memcg; 1281 } 1282 1283 /** 1284 * mem_cgroup_iter_break - abort a hierarchy walk prematurely 1285 * @root: hierarchy root 1286 * @prev: last visited hierarchy member as returned by mem_cgroup_iter() 1287 */ 1288 void mem_cgroup_iter_break(struct mem_cgroup *root, 1289 struct mem_cgroup *prev) 1290 { 1291 if (!root) 1292 root = root_mem_cgroup; 1293 if (prev && prev != root) 1294 css_put(&prev->css); 1295 } 1296 1297 /* 1298 * Iteration constructs for visiting all cgroups (under a tree). If 1299 * loops are exited prematurely (break), mem_cgroup_iter_break() must 1300 * be used for reference counting. 1301 */ 1302 #define for_each_mem_cgroup_tree(iter, root) \ 1303 for (iter = mem_cgroup_iter(root, NULL, NULL); \ 1304 iter != NULL; \ 1305 iter = mem_cgroup_iter(root, iter, NULL)) 1306 1307 #define for_each_mem_cgroup(iter) \ 1308 for (iter = mem_cgroup_iter(NULL, NULL, NULL); \ 1309 iter != NULL; \ 1310 iter = mem_cgroup_iter(NULL, iter, NULL)) 1311 1312 void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx) 1313 { 1314 struct mem_cgroup *memcg; 1315 1316 rcu_read_lock(); 1317 memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); 1318 if (unlikely(!memcg)) 1319 goto out; 1320 1321 switch (idx) { 1322 case PGFAULT: 1323 this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]); 1324 break; 1325 case PGMAJFAULT: 1326 this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]); 1327 break; 1328 default: 1329 BUG(); 1330 } 1331 out: 1332 rcu_read_unlock(); 1333 } 1334 EXPORT_SYMBOL(__mem_cgroup_count_vm_event); 1335 1336 /** 1337 * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg 1338 * @zone: zone of the wanted lruvec 1339 * @memcg: memcg of the wanted lruvec 1340 * 1341 * Returns the lru list vector holding pages for the given @zone and 1342 * @mem. This can be the global zone lruvec, if the memory controller 1343 * is disabled. 1344 */ 1345 struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone, 1346 struct mem_cgroup *memcg) 1347 { 1348 struct mem_cgroup_per_zone *mz; 1349 struct lruvec *lruvec; 1350 1351 if (mem_cgroup_disabled()) { 1352 lruvec = &zone->lruvec; 1353 goto out; 1354 } 1355 1356 mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone)); 1357 lruvec = &mz->lruvec; 1358 out: 1359 /* 1360 * Since a node can be onlined after the mem_cgroup was created, 1361 * we have to be prepared to initialize lruvec->zone here; 1362 * and if offlined then reonlined, we need to reinitialize it. 1363 */ 1364 if (unlikely(lruvec->zone != zone)) 1365 lruvec->zone = zone; 1366 return lruvec; 1367 } 1368 1369 /* 1370 * Following LRU functions are allowed to be used without PCG_LOCK. 1371 * Operations are called by routine of global LRU independently from memcg. 1372 * What we have to take care of here is validness of pc->mem_cgroup. 1373 * 1374 * Changes to pc->mem_cgroup happens when 1375 * 1. charge 1376 * 2. moving account 1377 * In typical case, "charge" is done before add-to-lru. Exception is SwapCache. 1378 * It is added to LRU before charge. 1379 * If PCG_USED bit is not set, page_cgroup is not added to this private LRU. 1380 * When moving account, the page is not on LRU. It's isolated. 1381 */ 1382 1383 /** 1384 * mem_cgroup_page_lruvec - return lruvec for adding an lru page 1385 * @page: the page 1386 * @zone: zone of the page 1387 */ 1388 struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone) 1389 { 1390 struct mem_cgroup_per_zone *mz; 1391 struct mem_cgroup *memcg; 1392 struct page_cgroup *pc; 1393 struct lruvec *lruvec; 1394 1395 if (mem_cgroup_disabled()) { 1396 lruvec = &zone->lruvec; 1397 goto out; 1398 } 1399 1400 pc = lookup_page_cgroup(page); 1401 memcg = pc->mem_cgroup; 1402 1403 /* 1404 * Surreptitiously switch any uncharged offlist page to root: 1405 * an uncharged page off lru does nothing to secure 1406 * its former mem_cgroup from sudden removal. 1407 * 1408 * Our caller holds lru_lock, and PageCgroupUsed is updated 1409 * under page_cgroup lock: between them, they make all uses 1410 * of pc->mem_cgroup safe. 1411 */ 1412 if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup) 1413 pc->mem_cgroup = memcg = root_mem_cgroup; 1414 1415 mz = page_cgroup_zoneinfo(memcg, page); 1416 lruvec = &mz->lruvec; 1417 out: 1418 /* 1419 * Since a node can be onlined after the mem_cgroup was created, 1420 * we have to be prepared to initialize lruvec->zone here; 1421 * and if offlined then reonlined, we need to reinitialize it. 1422 */ 1423 if (unlikely(lruvec->zone != zone)) 1424 lruvec->zone = zone; 1425 return lruvec; 1426 } 1427 1428 /** 1429 * mem_cgroup_update_lru_size - account for adding or removing an lru page 1430 * @lruvec: mem_cgroup per zone lru vector 1431 * @lru: index of lru list the page is sitting on 1432 * @nr_pages: positive when adding or negative when removing 1433 * 1434 * This function must be called when a page is added to or removed from an 1435 * lru list. 1436 */ 1437 void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, 1438 int nr_pages) 1439 { 1440 struct mem_cgroup_per_zone *mz; 1441 unsigned long *lru_size; 1442 1443 if (mem_cgroup_disabled()) 1444 return; 1445 1446 mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec); 1447 lru_size = mz->lru_size + lru; 1448 *lru_size += nr_pages; 1449 VM_BUG_ON((long)(*lru_size) < 0); 1450 } 1451 1452 /* 1453 * Checks whether given mem is same or in the root_mem_cgroup's 1454 * hierarchy subtree 1455 */ 1456 bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg, 1457 struct mem_cgroup *memcg) 1458 { 1459 if (root_memcg == memcg) 1460 return true; 1461 if (!root_memcg->use_hierarchy || !memcg) 1462 return false; 1463 return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup); 1464 } 1465 1466 static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg, 1467 struct mem_cgroup *memcg) 1468 { 1469 bool ret; 1470 1471 rcu_read_lock(); 1472 ret = __mem_cgroup_same_or_subtree(root_memcg, memcg); 1473 rcu_read_unlock(); 1474 return ret; 1475 } 1476 1477 bool task_in_mem_cgroup(struct task_struct *task, 1478 const struct mem_cgroup *memcg) 1479 { 1480 struct mem_cgroup *curr = NULL; 1481 struct task_struct *p; 1482 bool ret; 1483 1484 p = find_lock_task_mm(task); 1485 if (p) { 1486 curr = get_mem_cgroup_from_mm(p->mm); 1487 task_unlock(p); 1488 } else { 1489 /* 1490 * All threads may have already detached their mm's, but the oom 1491 * killer still needs to detect if they have already been oom 1492 * killed to prevent needlessly killing additional tasks. 1493 */ 1494 rcu_read_lock(); 1495 curr = mem_cgroup_from_task(task); 1496 if (curr) 1497 css_get(&curr->css); 1498 rcu_read_unlock(); 1499 } 1500 /* 1501 * We should check use_hierarchy of "memcg" not "curr". Because checking 1502 * use_hierarchy of "curr" here make this function true if hierarchy is 1503 * enabled in "curr" and "curr" is a child of "memcg" in *cgroup* 1504 * hierarchy(even if use_hierarchy is disabled in "memcg"). 1505 */ 1506 ret = mem_cgroup_same_or_subtree(memcg, curr); 1507 css_put(&curr->css); 1508 return ret; 1509 } 1510 1511 int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec) 1512 { 1513 unsigned long inactive_ratio; 1514 unsigned long inactive; 1515 unsigned long active; 1516 unsigned long gb; 1517 1518 inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON); 1519 active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON); 1520 1521 gb = (inactive + active) >> (30 - PAGE_SHIFT); 1522 if (gb) 1523 inactive_ratio = int_sqrt(10 * gb); 1524 else 1525 inactive_ratio = 1; 1526 1527 return inactive * inactive_ratio < active; 1528 } 1529 1530 #define mem_cgroup_from_res_counter(counter, member) \ 1531 container_of(counter, struct mem_cgroup, member) 1532 1533 /** 1534 * mem_cgroup_margin - calculate chargeable space of a memory cgroup 1535 * @memcg: the memory cgroup 1536 * 1537 * Returns the maximum amount of memory @mem can be charged with, in 1538 * pages. 1539 */ 1540 static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg) 1541 { 1542 unsigned long long margin; 1543 1544 margin = res_counter_margin(&memcg->res); 1545 if (do_swap_account) 1546 margin = min(margin, res_counter_margin(&memcg->memsw)); 1547 return margin >> PAGE_SHIFT; 1548 } 1549 1550 int mem_cgroup_swappiness(struct mem_cgroup *memcg) 1551 { 1552 /* root ? */ 1553 if (!css_parent(&memcg->css)) 1554 return vm_swappiness; 1555 1556 return memcg->swappiness; 1557 } 1558 1559 /* 1560 * memcg->moving_account is used for checking possibility that some thread is 1561 * calling move_account(). When a thread on CPU-A starts moving pages under 1562 * a memcg, other threads should check memcg->moving_account under 1563 * rcu_read_lock(), like this: 1564 * 1565 * CPU-A CPU-B 1566 * rcu_read_lock() 1567 * memcg->moving_account+1 if (memcg->mocing_account) 1568 * take heavy locks. 1569 * synchronize_rcu() update something. 1570 * rcu_read_unlock() 1571 * start move here. 1572 */ 1573 1574 /* for quick checking without looking up memcg */ 1575 atomic_t memcg_moving __read_mostly; 1576 1577 static void mem_cgroup_start_move(struct mem_cgroup *memcg) 1578 { 1579 atomic_inc(&memcg_moving); 1580 atomic_inc(&memcg->moving_account); 1581 synchronize_rcu(); 1582 } 1583 1584 static void mem_cgroup_end_move(struct mem_cgroup *memcg) 1585 { 1586 /* 1587 * Now, mem_cgroup_clear_mc() may call this function with NULL. 1588 * We check NULL in callee rather than caller. 1589 */ 1590 if (memcg) { 1591 atomic_dec(&memcg_moving); 1592 atomic_dec(&memcg->moving_account); 1593 } 1594 } 1595 1596 /* 1597 * A routine for checking "mem" is under move_account() or not. 1598 * 1599 * Checking a cgroup is mc.from or mc.to or under hierarchy of 1600 * moving cgroups. This is for waiting at high-memory pressure 1601 * caused by "move". 1602 */ 1603 static bool mem_cgroup_under_move(struct mem_cgroup *memcg) 1604 { 1605 struct mem_cgroup *from; 1606 struct mem_cgroup *to; 1607 bool ret = false; 1608 /* 1609 * Unlike task_move routines, we access mc.to, mc.from not under 1610 * mutual exclusion by cgroup_mutex. Here, we take spinlock instead. 1611 */ 1612 spin_lock(&mc.lock); 1613 from = mc.from; 1614 to = mc.to; 1615 if (!from) 1616 goto unlock; 1617 1618 ret = mem_cgroup_same_or_subtree(memcg, from) 1619 || mem_cgroup_same_or_subtree(memcg, to); 1620 unlock: 1621 spin_unlock(&mc.lock); 1622 return ret; 1623 } 1624 1625 static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg) 1626 { 1627 if (mc.moving_task && current != mc.moving_task) { 1628 if (mem_cgroup_under_move(memcg)) { 1629 DEFINE_WAIT(wait); 1630 prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE); 1631 /* moving charge context might have finished. */ 1632 if (mc.moving_task) 1633 schedule(); 1634 finish_wait(&mc.waitq, &wait); 1635 return true; 1636 } 1637 } 1638 return false; 1639 } 1640 1641 /* 1642 * Take this lock when 1643 * - a code tries to modify page's memcg while it's USED. 1644 * - a code tries to modify page state accounting in a memcg. 1645 */ 1646 static void move_lock_mem_cgroup(struct mem_cgroup *memcg, 1647 unsigned long *flags) 1648 { 1649 spin_lock_irqsave(&memcg->move_lock, *flags); 1650 } 1651 1652 static void move_unlock_mem_cgroup(struct mem_cgroup *memcg, 1653 unsigned long *flags) 1654 { 1655 spin_unlock_irqrestore(&memcg->move_lock, *flags); 1656 } 1657 1658 #define K(x) ((x) << (PAGE_SHIFT-10)) 1659 /** 1660 * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller. 1661 * @memcg: The memory cgroup that went over limit 1662 * @p: Task that is going to be killed 1663 * 1664 * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is 1665 * enabled 1666 */ 1667 void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) 1668 { 1669 /* oom_info_lock ensures that parallel ooms do not interleave */ 1670 static DEFINE_MUTEX(oom_info_lock); 1671 struct mem_cgroup *iter; 1672 unsigned int i; 1673 1674 if (!p) 1675 return; 1676 1677 mutex_lock(&oom_info_lock); 1678 rcu_read_lock(); 1679 1680 pr_info("Task in "); 1681 pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id)); 1682 pr_info(" killed as a result of limit of "); 1683 pr_cont_cgroup_path(memcg->css.cgroup); 1684 pr_info("\n"); 1685 1686 rcu_read_unlock(); 1687 1688 pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n", 1689 res_counter_read_u64(&memcg->res, RES_USAGE) >> 10, 1690 res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10, 1691 res_counter_read_u64(&memcg->res, RES_FAILCNT)); 1692 pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %llu\n", 1693 res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10, 1694 res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10, 1695 res_counter_read_u64(&memcg->memsw, RES_FAILCNT)); 1696 pr_info("kmem: usage %llukB, limit %llukB, failcnt %llu\n", 1697 res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10, 1698 res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10, 1699 res_counter_read_u64(&memcg->kmem, RES_FAILCNT)); 1700 1701 for_each_mem_cgroup_tree(iter, memcg) { 1702 pr_info("Memory cgroup stats for "); 1703 pr_cont_cgroup_path(iter->css.cgroup); 1704 pr_cont(":"); 1705 1706 for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { 1707 if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account) 1708 continue; 1709 pr_cont(" %s:%ldKB", mem_cgroup_stat_names[i], 1710 K(mem_cgroup_read_stat(iter, i))); 1711 } 1712 1713 for (i = 0; i < NR_LRU_LISTS; i++) 1714 pr_cont(" %s:%luKB", mem_cgroup_lru_names[i], 1715 K(mem_cgroup_nr_lru_pages(iter, BIT(i)))); 1716 1717 pr_cont("\n"); 1718 } 1719 mutex_unlock(&oom_info_lock); 1720 } 1721 1722 /* 1723 * This function returns the number of memcg under hierarchy tree. Returns 1724 * 1(self count) if no children. 1725 */ 1726 static int mem_cgroup_count_children(struct mem_cgroup *memcg) 1727 { 1728 int num = 0; 1729 struct mem_cgroup *iter; 1730 1731 for_each_mem_cgroup_tree(iter, memcg) 1732 num++; 1733 return num; 1734 } 1735 1736 /* 1737 * Return the memory (and swap, if configured) limit for a memcg. 1738 */ 1739 static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg) 1740 { 1741 u64 limit; 1742 1743 limit = res_counter_read_u64(&memcg->res, RES_LIMIT); 1744 1745 /* 1746 * Do not consider swap space if we cannot swap due to swappiness 1747 */ 1748 if (mem_cgroup_swappiness(memcg)) { 1749 u64 memsw; 1750 1751 limit += total_swap_pages << PAGE_SHIFT; 1752 memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 1753 1754 /* 1755 * If memsw is finite and limits the amount of swap space 1756 * available to this memcg, return that limit. 1757 */ 1758 limit = min(limit, memsw); 1759 } 1760 1761 return limit; 1762 } 1763 1764 static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, 1765 int order) 1766 { 1767 struct mem_cgroup *iter; 1768 unsigned long chosen_points = 0; 1769 unsigned long totalpages; 1770 unsigned int points = 0; 1771 struct task_struct *chosen = NULL; 1772 1773 /* 1774 * If current has a pending SIGKILL or is exiting, then automatically 1775 * select it. The goal is to allow it to allocate so that it may 1776 * quickly exit and free its memory. 1777 */ 1778 if (fatal_signal_pending(current) || current->flags & PF_EXITING) { 1779 set_thread_flag(TIF_MEMDIE); 1780 return; 1781 } 1782 1783 check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL); 1784 totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1; 1785 for_each_mem_cgroup_tree(iter, memcg) { 1786 struct css_task_iter it; 1787 struct task_struct *task; 1788 1789 css_task_iter_start(&iter->css, &it); 1790 while ((task = css_task_iter_next(&it))) { 1791 switch (oom_scan_process_thread(task, totalpages, NULL, 1792 false)) { 1793 case OOM_SCAN_SELECT: 1794 if (chosen) 1795 put_task_struct(chosen); 1796 chosen = task; 1797 chosen_points = ULONG_MAX; 1798 get_task_struct(chosen); 1799 /* fall through */ 1800 case OOM_SCAN_CONTINUE: 1801 continue; 1802 case OOM_SCAN_ABORT: 1803 css_task_iter_end(&it); 1804 mem_cgroup_iter_break(memcg, iter); 1805 if (chosen) 1806 put_task_struct(chosen); 1807 return; 1808 case OOM_SCAN_OK: 1809 break; 1810 }; 1811 points = oom_badness(task, memcg, NULL, totalpages); 1812 if (!points || points < chosen_points) 1813 continue; 1814 /* Prefer thread group leaders for display purposes */ 1815 if (points == chosen_points && 1816 thread_group_leader(chosen)) 1817 continue; 1818 1819 if (chosen) 1820 put_task_struct(chosen); 1821 chosen = task; 1822 chosen_points = points; 1823 get_task_struct(chosen); 1824 } 1825 css_task_iter_end(&it); 1826 } 1827 1828 if (!chosen) 1829 return; 1830 points = chosen_points * 1000 / totalpages; 1831 oom_kill_process(chosen, gfp_mask, order, points, totalpages, memcg, 1832 NULL, "Memory cgroup out of memory"); 1833 } 1834 1835 static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg, 1836 gfp_t gfp_mask, 1837 unsigned long flags) 1838 { 1839 unsigned long total = 0; 1840 bool noswap = false; 1841 int loop; 1842 1843 if (flags & MEM_CGROUP_RECLAIM_NOSWAP) 1844 noswap = true; 1845 if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum) 1846 noswap = true; 1847 1848 for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) { 1849 if (loop) 1850 drain_all_stock_async(memcg); 1851 total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap); 1852 /* 1853 * Allow limit shrinkers, which are triggered directly 1854 * by userspace, to catch signals and stop reclaim 1855 * after minimal progress, regardless of the margin. 1856 */ 1857 if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK)) 1858 break; 1859 if (mem_cgroup_margin(memcg)) 1860 break; 1861 /* 1862 * If nothing was reclaimed after two attempts, there 1863 * may be no reclaimable pages in this hierarchy. 1864 */ 1865 if (loop && !total) 1866 break; 1867 } 1868 return total; 1869 } 1870 1871 /** 1872 * test_mem_cgroup_node_reclaimable 1873 * @memcg: the target memcg 1874 * @nid: the node ID to be checked. 1875 * @noswap : specify true here if the user wants flle only information. 1876 * 1877 * This function returns whether the specified memcg contains any 1878 * reclaimable pages on a node. Returns true if there are any reclaimable 1879 * pages in the node. 1880 */ 1881 static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg, 1882 int nid, bool noswap) 1883 { 1884 if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE)) 1885 return true; 1886 if (noswap || !total_swap_pages) 1887 return false; 1888 if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON)) 1889 return true; 1890 return false; 1891 1892 } 1893 #if MAX_NUMNODES > 1 1894 1895 /* 1896 * Always updating the nodemask is not very good - even if we have an empty 1897 * list or the wrong list here, we can start from some node and traverse all 1898 * nodes based on the zonelist. So update the list loosely once per 10 secs. 1899 * 1900 */ 1901 static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg) 1902 { 1903 int nid; 1904 /* 1905 * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET 1906 * pagein/pageout changes since the last update. 1907 */ 1908 if (!atomic_read(&memcg->numainfo_events)) 1909 return; 1910 if (atomic_inc_return(&memcg->numainfo_updating) > 1) 1911 return; 1912 1913 /* make a nodemask where this memcg uses memory from */ 1914 memcg->scan_nodes = node_states[N_MEMORY]; 1915 1916 for_each_node_mask(nid, node_states[N_MEMORY]) { 1917 1918 if (!test_mem_cgroup_node_reclaimable(memcg, nid, false)) 1919 node_clear(nid, memcg->scan_nodes); 1920 } 1921 1922 atomic_set(&memcg->numainfo_events, 0); 1923 atomic_set(&memcg->numainfo_updating, 0); 1924 } 1925 1926 /* 1927 * Selecting a node where we start reclaim from. Because what we need is just 1928 * reducing usage counter, start from anywhere is O,K. Considering 1929 * memory reclaim from current node, there are pros. and cons. 1930 * 1931 * Freeing memory from current node means freeing memory from a node which 1932 * we'll use or we've used. So, it may make LRU bad. And if several threads 1933 * hit limits, it will see a contention on a node. But freeing from remote 1934 * node means more costs for memory reclaim because of memory latency. 1935 * 1936 * Now, we use round-robin. Better algorithm is welcomed. 1937 */ 1938 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) 1939 { 1940 int node; 1941 1942 mem_cgroup_may_update_nodemask(memcg); 1943 node = memcg->last_scanned_node; 1944 1945 node = next_node(node, memcg->scan_nodes); 1946 if (node == MAX_NUMNODES) 1947 node = first_node(memcg->scan_nodes); 1948 /* 1949 * We call this when we hit limit, not when pages are added to LRU. 1950 * No LRU may hold pages because all pages are UNEVICTABLE or 1951 * memcg is too small and all pages are not on LRU. In that case, 1952 * we use curret node. 1953 */ 1954 if (unlikely(node == MAX_NUMNODES)) 1955 node = numa_node_id(); 1956 1957 memcg->last_scanned_node = node; 1958 return node; 1959 } 1960 1961 /* 1962 * Check all nodes whether it contains reclaimable pages or not. 1963 * For quick scan, we make use of scan_nodes. This will allow us to skip 1964 * unused nodes. But scan_nodes is lazily updated and may not cotain 1965 * enough new information. We need to do double check. 1966 */ 1967 static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) 1968 { 1969 int nid; 1970 1971 /* 1972 * quick check...making use of scan_node. 1973 * We can skip unused nodes. 1974 */ 1975 if (!nodes_empty(memcg->scan_nodes)) { 1976 for (nid = first_node(memcg->scan_nodes); 1977 nid < MAX_NUMNODES; 1978 nid = next_node(nid, memcg->scan_nodes)) { 1979 1980 if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap)) 1981 return true; 1982 } 1983 } 1984 /* 1985 * Check rest of nodes. 1986 */ 1987 for_each_node_state(nid, N_MEMORY) { 1988 if (node_isset(nid, memcg->scan_nodes)) 1989 continue; 1990 if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap)) 1991 return true; 1992 } 1993 return false; 1994 } 1995 1996 #else 1997 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) 1998 { 1999 return 0; 2000 } 2001 2002 static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) 2003 { 2004 return test_mem_cgroup_node_reclaimable(memcg, 0, noswap); 2005 } 2006 #endif 2007 2008 static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, 2009 struct zone *zone, 2010 gfp_t gfp_mask, 2011 unsigned long *total_scanned) 2012 { 2013 struct mem_cgroup *victim = NULL; 2014 int total = 0; 2015 int loop = 0; 2016 unsigned long excess; 2017 unsigned long nr_scanned; 2018 struct mem_cgroup_reclaim_cookie reclaim = { 2019 .zone = zone, 2020 .priority = 0, 2021 }; 2022 2023 excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT; 2024 2025 while (1) { 2026 victim = mem_cgroup_iter(root_memcg, victim, &reclaim); 2027 if (!victim) { 2028 loop++; 2029 if (loop >= 2) { 2030 /* 2031 * If we have not been able to reclaim 2032 * anything, it might because there are 2033 * no reclaimable pages under this hierarchy 2034 */ 2035 if (!total) 2036 break; 2037 /* 2038 * We want to do more targeted reclaim. 2039 * excess >> 2 is not to excessive so as to 2040 * reclaim too much, nor too less that we keep 2041 * coming back to reclaim from this cgroup 2042 */ 2043 if (total >= (excess >> 2) || 2044 (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) 2045 break; 2046 } 2047 continue; 2048 } 2049 if (!mem_cgroup_reclaimable(victim, false)) 2050 continue; 2051 total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false, 2052 zone, &nr_scanned); 2053 *total_scanned += nr_scanned; 2054 if (!res_counter_soft_limit_excess(&root_memcg->res)) 2055 break; 2056 } 2057 mem_cgroup_iter_break(root_memcg, victim); 2058 return total; 2059 } 2060 2061 #ifdef CONFIG_LOCKDEP 2062 static struct lockdep_map memcg_oom_lock_dep_map = { 2063 .name = "memcg_oom_lock", 2064 }; 2065 #endif 2066 2067 static DEFINE_SPINLOCK(memcg_oom_lock); 2068 2069 /* 2070 * Check OOM-Killer is already running under our hierarchy. 2071 * If someone is running, return false. 2072 */ 2073 static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg) 2074 { 2075 struct mem_cgroup *iter, *failed = NULL; 2076 2077 spin_lock(&memcg_oom_lock); 2078 2079 for_each_mem_cgroup_tree(iter, memcg) { 2080 if (iter->oom_lock) { 2081 /* 2082 * this subtree of our hierarchy is already locked 2083 * so we cannot give a lock. 2084 */ 2085 failed = iter; 2086 mem_cgroup_iter_break(memcg, iter); 2087 break; 2088 } else 2089 iter->oom_lock = true; 2090 } 2091 2092 if (failed) { 2093 /* 2094 * OK, we failed to lock the whole subtree so we have 2095 * to clean up what we set up to the failing subtree 2096 */ 2097 for_each_mem_cgroup_tree(iter, memcg) { 2098 if (iter == failed) { 2099 mem_cgroup_iter_break(memcg, iter); 2100 break; 2101 } 2102 iter->oom_lock = false; 2103 } 2104 } else 2105 mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_); 2106 2107 spin_unlock(&memcg_oom_lock); 2108 2109 return !failed; 2110 } 2111 2112 static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg) 2113 { 2114 struct mem_cgroup *iter; 2115 2116 spin_lock(&memcg_oom_lock); 2117 mutex_release(&memcg_oom_lock_dep_map, 1, _RET_IP_); 2118 for_each_mem_cgroup_tree(iter, memcg) 2119 iter->oom_lock = false; 2120 spin_unlock(&memcg_oom_lock); 2121 } 2122 2123 static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg) 2124 { 2125 struct mem_cgroup *iter; 2126 2127 for_each_mem_cgroup_tree(iter, memcg) 2128 atomic_inc(&iter->under_oom); 2129 } 2130 2131 static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg) 2132 { 2133 struct mem_cgroup *iter; 2134 2135 /* 2136 * When a new child is created while the hierarchy is under oom, 2137 * mem_cgroup_oom_lock() may not be called. We have to use 2138 * atomic_add_unless() here. 2139 */ 2140 for_each_mem_cgroup_tree(iter, memcg) 2141 atomic_add_unless(&iter->under_oom, -1, 0); 2142 } 2143 2144 static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); 2145 2146 struct oom_wait_info { 2147 struct mem_cgroup *memcg; 2148 wait_queue_t wait; 2149 }; 2150 2151 static int memcg_oom_wake_function(wait_queue_t *wait, 2152 unsigned mode, int sync, void *arg) 2153 { 2154 struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg; 2155 struct mem_cgroup *oom_wait_memcg; 2156 struct oom_wait_info *oom_wait_info; 2157 2158 oom_wait_info = container_of(wait, struct oom_wait_info, wait); 2159 oom_wait_memcg = oom_wait_info->memcg; 2160 2161 /* 2162 * Both of oom_wait_info->memcg and wake_memcg are stable under us. 2163 * Then we can use css_is_ancestor without taking care of RCU. 2164 */ 2165 if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg) 2166 && !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg)) 2167 return 0; 2168 return autoremove_wake_function(wait, mode, sync, arg); 2169 } 2170 2171 static void memcg_wakeup_oom(struct mem_cgroup *memcg) 2172 { 2173 atomic_inc(&memcg->oom_wakeups); 2174 /* for filtering, pass "memcg" as argument. */ 2175 __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); 2176 } 2177 2178 static void memcg_oom_recover(struct mem_cgroup *memcg) 2179 { 2180 if (memcg && atomic_read(&memcg->under_oom)) 2181 memcg_wakeup_oom(memcg); 2182 } 2183 2184 static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order) 2185 { 2186 if (!current->memcg_oom.may_oom) 2187 return; 2188 /* 2189 * We are in the middle of the charge context here, so we 2190 * don't want to block when potentially sitting on a callstack 2191 * that holds all kinds of filesystem and mm locks. 2192 * 2193 * Also, the caller may handle a failed allocation gracefully 2194 * (like optional page cache readahead) and so an OOM killer 2195 * invocation might not even be necessary. 2196 * 2197 * That's why we don't do anything here except remember the 2198 * OOM context and then deal with it at the end of the page 2199 * fault when the stack is unwound, the locks are released, 2200 * and when we know whether the fault was overall successful. 2201 */ 2202 css_get(&memcg->css); 2203 current->memcg_oom.memcg = memcg; 2204 current->memcg_oom.gfp_mask = mask; 2205 current->memcg_oom.order = order; 2206 } 2207 2208 /** 2209 * mem_cgroup_oom_synchronize - complete memcg OOM handling 2210 * @handle: actually kill/wait or just clean up the OOM state 2211 * 2212 * This has to be called at the end of a page fault if the memcg OOM 2213 * handler was enabled. 2214 * 2215 * Memcg supports userspace OOM handling where failed allocations must 2216 * sleep on a waitqueue until the userspace task resolves the 2217 * situation. Sleeping directly in the charge context with all kinds 2218 * of locks held is not a good idea, instead we remember an OOM state 2219 * in the task and mem_cgroup_oom_synchronize() has to be called at 2220 * the end of the page fault to complete the OOM handling. 2221 * 2222 * Returns %true if an ongoing memcg OOM situation was detected and 2223 * completed, %false otherwise. 2224 */ 2225 bool mem_cgroup_oom_synchronize(bool handle) 2226 { 2227 struct mem_cgroup *memcg = current->memcg_oom.memcg; 2228 struct oom_wait_info owait; 2229 bool locked; 2230 2231 /* OOM is global, do not handle */ 2232 if (!memcg) 2233 return false; 2234 2235 if (!handle) 2236 goto cleanup; 2237 2238 owait.memcg = memcg; 2239 owait.wait.flags = 0; 2240 owait.wait.func = memcg_oom_wake_function; 2241 owait.wait.private = current; 2242 INIT_LIST_HEAD(&owait.wait.task_list); 2243 2244 prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); 2245 mem_cgroup_mark_under_oom(memcg); 2246 2247 locked = mem_cgroup_oom_trylock(memcg); 2248 2249 if (locked) 2250 mem_cgroup_oom_notify(memcg); 2251 2252 if (locked && !memcg->oom_kill_disable) { 2253 mem_cgroup_unmark_under_oom(memcg); 2254 finish_wait(&memcg_oom_waitq, &owait.wait); 2255 mem_cgroup_out_of_memory(memcg, current->memcg_oom.gfp_mask, 2256 current->memcg_oom.order); 2257 } else { 2258 schedule(); 2259 mem_cgroup_unmark_under_oom(memcg); 2260 finish_wait(&memcg_oom_waitq, &owait.wait); 2261 } 2262 2263 if (locked) { 2264 mem_cgroup_oom_unlock(memcg); 2265 /* 2266 * There is no guarantee that an OOM-lock contender 2267 * sees the wakeups triggered by the OOM kill 2268 * uncharges. Wake any sleepers explicitely. 2269 */ 2270 memcg_oom_recover(memcg); 2271 } 2272 cleanup: 2273 current->memcg_oom.memcg = NULL; 2274 css_put(&memcg->css); 2275 return true; 2276 } 2277 2278 /* 2279 * Used to update mapped file or writeback or other statistics. 2280 * 2281 * Notes: Race condition 2282 * 2283 * We usually use lock_page_cgroup() for accessing page_cgroup member but 2284 * it tends to be costly. But considering some conditions, we doesn't need 2285 * to do so _always_. 2286 * 2287 * Considering "charge", lock_page_cgroup() is not required because all 2288 * file-stat operations happen after a page is attached to radix-tree. There 2289 * are no race with "charge". 2290 * 2291 * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup 2292 * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even 2293 * if there are race with "uncharge". Statistics itself is properly handled 2294 * by flags. 2295 * 2296 * Considering "move", this is an only case we see a race. To make the race 2297 * small, we check memcg->moving_account and detect there are possibility 2298 * of race or not. If there is, we take a lock. 2299 */ 2300 2301 void __mem_cgroup_begin_update_page_stat(struct page *page, 2302 bool *locked, unsigned long *flags) 2303 { 2304 struct mem_cgroup *memcg; 2305 struct page_cgroup *pc; 2306 2307 pc = lookup_page_cgroup(page); 2308 again: 2309 memcg = pc->mem_cgroup; 2310 if (unlikely(!memcg || !PageCgroupUsed(pc))) 2311 return; 2312 /* 2313 * If this memory cgroup is not under account moving, we don't 2314 * need to take move_lock_mem_cgroup(). Because we already hold 2315 * rcu_read_lock(), any calls to move_account will be delayed until 2316 * rcu_read_unlock(). 2317 */ 2318 VM_BUG_ON(!rcu_read_lock_held()); 2319 if (atomic_read(&memcg->moving_account) <= 0) 2320 return; 2321 2322 move_lock_mem_cgroup(memcg, flags); 2323 if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) { 2324 move_unlock_mem_cgroup(memcg, flags); 2325 goto again; 2326 } 2327 *locked = true; 2328 } 2329 2330 void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags) 2331 { 2332 struct page_cgroup *pc = lookup_page_cgroup(page); 2333 2334 /* 2335 * It's guaranteed that pc->mem_cgroup never changes while 2336 * lock is held because a routine modifies pc->mem_cgroup 2337 * should take move_lock_mem_cgroup(). 2338 */ 2339 move_unlock_mem_cgroup(pc->mem_cgroup, flags); 2340 } 2341 2342 void mem_cgroup_update_page_stat(struct page *page, 2343 enum mem_cgroup_stat_index idx, int val) 2344 { 2345 struct mem_cgroup *memcg; 2346 struct page_cgroup *pc = lookup_page_cgroup(page); 2347 unsigned long uninitialized_var(flags); 2348 2349 if (mem_cgroup_disabled()) 2350 return; 2351 2352 VM_BUG_ON(!rcu_read_lock_held()); 2353 memcg = pc->mem_cgroup; 2354 if (unlikely(!memcg || !PageCgroupUsed(pc))) 2355 return; 2356 2357 this_cpu_add(memcg->stat->count[idx], val); 2358 } 2359 2360 /* 2361 * size of first charge trial. "32" comes from vmscan.c's magic value. 2362 * TODO: maybe necessary to use big numbers in big irons. 2363 */ 2364 #define CHARGE_BATCH 32U 2365 struct memcg_stock_pcp { 2366 struct mem_cgroup *cached; /* this never be root cgroup */ 2367 unsigned int nr_pages; 2368 struct work_struct work; 2369 unsigned long flags; 2370 #define FLUSHING_CACHED_CHARGE 0 2371 }; 2372 static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); 2373 static DEFINE_MUTEX(percpu_charge_mutex); 2374 2375 /** 2376 * consume_stock: Try to consume stocked charge on this cpu. 2377 * @memcg: memcg to consume from. 2378 * @nr_pages: how many pages to charge. 2379 * 2380 * The charges will only happen if @memcg matches the current cpu's memcg 2381 * stock, and at least @nr_pages are available in that stock. Failure to 2382 * service an allocation will refill the stock. 2383 * 2384 * returns true if successful, false otherwise. 2385 */ 2386 static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) 2387 { 2388 struct memcg_stock_pcp *stock; 2389 bool ret = true; 2390 2391 if (nr_pages > CHARGE_BATCH) 2392 return false; 2393 2394 stock = &get_cpu_var(memcg_stock); 2395 if (memcg == stock->cached && stock->nr_pages >= nr_pages) 2396 stock->nr_pages -= nr_pages; 2397 else /* need to call res_counter_charge */ 2398 ret = false; 2399 put_cpu_var(memcg_stock); 2400 return ret; 2401 } 2402 2403 /* 2404 * Returns stocks cached in percpu to res_counter and reset cached information. 2405 */ 2406 static void drain_stock(struct memcg_stock_pcp *stock) 2407 { 2408 struct mem_cgroup *old = stock->cached; 2409 2410 if (stock->nr_pages) { 2411 unsigned long bytes = stock->nr_pages * PAGE_SIZE; 2412 2413 res_counter_uncharge(&old->res, bytes); 2414 if (do_swap_account) 2415 res_counter_uncharge(&old->memsw, bytes); 2416 stock->nr_pages = 0; 2417 } 2418 stock->cached = NULL; 2419 } 2420 2421 /* 2422 * This must be called under preempt disabled or must be called by 2423 * a thread which is pinned to local cpu. 2424 */ 2425 static void drain_local_stock(struct work_struct *dummy) 2426 { 2427 struct memcg_stock_pcp *stock = this_cpu_ptr(&memcg_stock); 2428 drain_stock(stock); 2429 clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); 2430 } 2431 2432 static void __init memcg_stock_init(void) 2433 { 2434 int cpu; 2435 2436 for_each_possible_cpu(cpu) { 2437 struct memcg_stock_pcp *stock = 2438 &per_cpu(memcg_stock, cpu); 2439 INIT_WORK(&stock->work, drain_local_stock); 2440 } 2441 } 2442 2443 /* 2444 * Cache charges(val) which is from res_counter, to local per_cpu area. 2445 * This will be consumed by consume_stock() function, later. 2446 */ 2447 static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) 2448 { 2449 struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock); 2450 2451 if (stock->cached != memcg) { /* reset if necessary */ 2452 drain_stock(stock); 2453 stock->cached = memcg; 2454 } 2455 stock->nr_pages += nr_pages; 2456 put_cpu_var(memcg_stock); 2457 } 2458 2459 /* 2460 * Drains all per-CPU charge caches for given root_memcg resp. subtree 2461 * of the hierarchy under it. sync flag says whether we should block 2462 * until the work is done. 2463 */ 2464 static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync) 2465 { 2466 int cpu, curcpu; 2467 2468 /* Notify other cpus that system-wide "drain" is running */ 2469 get_online_cpus(); 2470 curcpu = get_cpu(); 2471 for_each_online_cpu(cpu) { 2472 struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); 2473 struct mem_cgroup *memcg; 2474 2475 memcg = stock->cached; 2476 if (!memcg || !stock->nr_pages) 2477 continue; 2478 if (!mem_cgroup_same_or_subtree(root_memcg, memcg)) 2479 continue; 2480 if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) { 2481 if (cpu == curcpu) 2482 drain_local_stock(&stock->work); 2483 else 2484 schedule_work_on(cpu, &stock->work); 2485 } 2486 } 2487 put_cpu(); 2488 2489 if (!sync) 2490 goto out; 2491 2492 for_each_online_cpu(cpu) { 2493 struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); 2494 if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) 2495 flush_work(&stock->work); 2496 } 2497 out: 2498 put_online_cpus(); 2499 } 2500 2501 /* 2502 * Tries to drain stocked charges in other cpus. This function is asynchronous 2503 * and just put a work per cpu for draining localy on each cpu. Caller can 2504 * expects some charges will be back to res_counter later but cannot wait for 2505 * it. 2506 */ 2507 static void drain_all_stock_async(struct mem_cgroup *root_memcg) 2508 { 2509 /* 2510 * If someone calls draining, avoid adding more kworker runs. 2511 */ 2512 if (!mutex_trylock(&percpu_charge_mutex)) 2513 return; 2514 drain_all_stock(root_memcg, false); 2515 mutex_unlock(&percpu_charge_mutex); 2516 } 2517 2518 /* This is a synchronous drain interface. */ 2519 static void drain_all_stock_sync(struct mem_cgroup *root_memcg) 2520 { 2521 /* called when force_empty is called */ 2522 mutex_lock(&percpu_charge_mutex); 2523 drain_all_stock(root_memcg, true); 2524 mutex_unlock(&percpu_charge_mutex); 2525 } 2526 2527 /* 2528 * This function drains percpu counter value from DEAD cpu and 2529 * move it to local cpu. Note that this function can be preempted. 2530 */ 2531 static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu) 2532 { 2533 int i; 2534 2535 spin_lock(&memcg->pcp_counter_lock); 2536 for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { 2537 long x = per_cpu(memcg->stat->count[i], cpu); 2538 2539 per_cpu(memcg->stat->count[i], cpu) = 0; 2540 memcg->nocpu_base.count[i] += x; 2541 } 2542 for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) { 2543 unsigned long x = per_cpu(memcg->stat->events[i], cpu); 2544 2545 per_cpu(memcg->stat->events[i], cpu) = 0; 2546 memcg->nocpu_base.events[i] += x; 2547 } 2548 spin_unlock(&memcg->pcp_counter_lock); 2549 } 2550 2551 static int memcg_cpu_hotplug_callback(struct notifier_block *nb, 2552 unsigned long action, 2553 void *hcpu) 2554 { 2555 int cpu = (unsigned long)hcpu; 2556 struct memcg_stock_pcp *stock; 2557 struct mem_cgroup *iter; 2558 2559 if (action == CPU_ONLINE) 2560 return NOTIFY_OK; 2561 2562 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) 2563 return NOTIFY_OK; 2564 2565 for_each_mem_cgroup(iter) 2566 mem_cgroup_drain_pcp_counter(iter, cpu); 2567 2568 stock = &per_cpu(memcg_stock, cpu); 2569 drain_stock(stock); 2570 return NOTIFY_OK; 2571 } 2572 2573 2574 /* See mem_cgroup_try_charge() for details */ 2575 enum { 2576 CHARGE_OK, /* success */ 2577 CHARGE_RETRY, /* need to retry but retry is not bad */ 2578 CHARGE_NOMEM, /* we can't do more. return -ENOMEM */ 2579 CHARGE_WOULDBLOCK, /* GFP_WAIT wasn't set and no enough res. */ 2580 }; 2581 2582 static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, 2583 unsigned int nr_pages, unsigned int min_pages, 2584 bool invoke_oom) 2585 { 2586 unsigned long csize = nr_pages * PAGE_SIZE; 2587 struct mem_cgroup *mem_over_limit; 2588 struct res_counter *fail_res; 2589 unsigned long flags = 0; 2590 int ret; 2591 2592 ret = res_counter_charge(&memcg->res, csize, &fail_res); 2593 2594 if (likely(!ret)) { 2595 if (!do_swap_account) 2596 return CHARGE_OK; 2597 ret = res_counter_charge(&memcg->memsw, csize, &fail_res); 2598 if (likely(!ret)) 2599 return CHARGE_OK; 2600 2601 res_counter_uncharge(&memcg->res, csize); 2602 mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw); 2603 flags |= MEM_CGROUP_RECLAIM_NOSWAP; 2604 } else 2605 mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); 2606 /* 2607 * Never reclaim on behalf of optional batching, retry with a 2608 * single page instead. 2609 */ 2610 if (nr_pages > min_pages) 2611 return CHARGE_RETRY; 2612 2613 if (!(gfp_mask & __GFP_WAIT)) 2614 return CHARGE_WOULDBLOCK; 2615 2616 if (gfp_mask & __GFP_NORETRY) 2617 return CHARGE_NOMEM; 2618 2619 ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); 2620 if (mem_cgroup_margin(mem_over_limit) >= nr_pages) 2621 return CHARGE_RETRY; 2622 /* 2623 * Even though the limit is exceeded at this point, reclaim 2624 * may have been able to free some pages. Retry the charge 2625 * before killing the task. 2626 * 2627 * Only for regular pages, though: huge pages are rather 2628 * unlikely to succeed so close to the limit, and we fall back 2629 * to regular pages anyway in case of failure. 2630 */ 2631 if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret) 2632 return CHARGE_RETRY; 2633 2634 /* 2635 * At task move, charge accounts can be doubly counted. So, it's 2636 * better to wait until the end of task_move if something is going on. 2637 */ 2638 if (mem_cgroup_wait_acct_move(mem_over_limit)) 2639 return CHARGE_RETRY; 2640 2641 if (invoke_oom) 2642 mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize)); 2643 2644 return CHARGE_NOMEM; 2645 } 2646 2647 /** 2648 * mem_cgroup_try_charge - try charging a memcg 2649 * @memcg: memcg to charge 2650 * @nr_pages: number of pages to charge 2651 * @oom: trigger OOM if reclaim fails 2652 * 2653 * Returns 0 if @memcg was charged successfully, -EINTR if the charge 2654 * was bypassed to root_mem_cgroup, and -ENOMEM if the charge failed. 2655 */ 2656 static int mem_cgroup_try_charge(struct mem_cgroup *memcg, 2657 gfp_t gfp_mask, 2658 unsigned int nr_pages, 2659 bool oom) 2660 { 2661 unsigned int batch = max(CHARGE_BATCH, nr_pages); 2662 int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; 2663 int ret; 2664 2665 if (mem_cgroup_is_root(memcg)) 2666 goto done; 2667 /* 2668 * Unlike in global OOM situations, memcg is not in a physical 2669 * memory shortage. Allow dying and OOM-killed tasks to 2670 * bypass the last charges so that they can exit quickly and 2671 * free their memory. 2672 */ 2673 if (unlikely(test_thread_flag(TIF_MEMDIE) || 2674 fatal_signal_pending(current) || 2675 current->flags & PF_EXITING)) 2676 goto bypass; 2677 2678 if (unlikely(task_in_memcg_oom(current))) 2679 goto nomem; 2680 2681 if (gfp_mask & __GFP_NOFAIL) 2682 oom = false; 2683 again: 2684 if (consume_stock(memcg, nr_pages)) 2685 goto done; 2686 2687 do { 2688 bool invoke_oom = oom && !nr_oom_retries; 2689 2690 /* If killed, bypass charge */ 2691 if (fatal_signal_pending(current)) 2692 goto bypass; 2693 2694 ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, 2695 nr_pages, invoke_oom); 2696 switch (ret) { 2697 case CHARGE_OK: 2698 break; 2699 case CHARGE_RETRY: /* not in OOM situation but retry */ 2700 batch = nr_pages; 2701 goto again; 2702 case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */ 2703 goto nomem; 2704 case CHARGE_NOMEM: /* OOM routine works */ 2705 if (!oom || invoke_oom) 2706 goto nomem; 2707 nr_oom_retries--; 2708 break; 2709 } 2710 } while (ret != CHARGE_OK); 2711 2712 if (batch > nr_pages) 2713 refill_stock(memcg, batch - nr_pages); 2714 done: 2715 return 0; 2716 nomem: 2717 if (!(gfp_mask & __GFP_NOFAIL)) 2718 return -ENOMEM; 2719 bypass: 2720 return -EINTR; 2721 } 2722 2723 /** 2724 * mem_cgroup_try_charge_mm - try charging a mm 2725 * @mm: mm_struct to charge 2726 * @nr_pages: number of pages to charge 2727 * @oom: trigger OOM if reclaim fails 2728 * 2729 * Returns the charged mem_cgroup associated with the given mm_struct or 2730 * NULL the charge failed. 2731 */ 2732 static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm, 2733 gfp_t gfp_mask, 2734 unsigned int nr_pages, 2735 bool oom) 2736 2737 { 2738 struct mem_cgroup *memcg; 2739 int ret; 2740 2741 memcg = get_mem_cgroup_from_mm(mm); 2742 ret = mem_cgroup_try_charge(memcg, gfp_mask, nr_pages, oom); 2743 css_put(&memcg->css); 2744 if (ret == -EINTR) 2745 memcg = root_mem_cgroup; 2746 else if (ret) 2747 memcg = NULL; 2748 2749 return memcg; 2750 } 2751 2752 /* 2753 * Somemtimes we have to undo a charge we got by try_charge(). 2754 * This function is for that and do uncharge, put css's refcnt. 2755 * gotten by try_charge(). 2756 */ 2757 static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg, 2758 unsigned int nr_pages) 2759 { 2760 if (!mem_cgroup_is_root(memcg)) { 2761 unsigned long bytes = nr_pages * PAGE_SIZE; 2762 2763 res_counter_uncharge(&memcg->res, bytes); 2764 if (do_swap_account) 2765 res_counter_uncharge(&memcg->memsw, bytes); 2766 } 2767 } 2768 2769 /* 2770 * Cancel chrages in this cgroup....doesn't propagate to parent cgroup. 2771 * This is useful when moving usage to parent cgroup. 2772 */ 2773 static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg, 2774 unsigned int nr_pages) 2775 { 2776 unsigned long bytes = nr_pages * PAGE_SIZE; 2777 2778 if (mem_cgroup_is_root(memcg)) 2779 return; 2780 2781 res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes); 2782 if (do_swap_account) 2783 res_counter_uncharge_until(&memcg->memsw, 2784 memcg->memsw.parent, bytes); 2785 } 2786 2787 /* 2788 * A helper function to get mem_cgroup from ID. must be called under 2789 * rcu_read_lock(). The caller is responsible for calling css_tryget if 2790 * the mem_cgroup is used for charging. (dropping refcnt from swap can be 2791 * called against removed memcg.) 2792 */ 2793 static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) 2794 { 2795 /* ID 0 is unused ID */ 2796 if (!id) 2797 return NULL; 2798 return mem_cgroup_from_id(id); 2799 } 2800 2801 struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) 2802 { 2803 struct mem_cgroup *memcg = NULL; 2804 struct page_cgroup *pc; 2805 unsigned short id; 2806 swp_entry_t ent; 2807 2808 VM_BUG_ON_PAGE(!PageLocked(page), page); 2809 2810 pc = lookup_page_cgroup(page); 2811 lock_page_cgroup(pc); 2812 if (PageCgroupUsed(pc)) { 2813 memcg = pc->mem_cgroup; 2814 if (memcg && !css_tryget(&memcg->css)) 2815 memcg = NULL; 2816 } else if (PageSwapCache(page)) { 2817 ent.val = page_private(page); 2818 id = lookup_swap_cgroup_id(ent); 2819 rcu_read_lock(); 2820 memcg = mem_cgroup_lookup(id); 2821 if (memcg && !css_tryget(&memcg->css)) 2822 memcg = NULL; 2823 rcu_read_unlock(); 2824 } 2825 unlock_page_cgroup(pc); 2826 return memcg; 2827 } 2828 2829 static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, 2830 struct page *page, 2831 unsigned int nr_pages, 2832 enum charge_type ctype, 2833 bool lrucare) 2834 { 2835 struct page_cgroup *pc = lookup_page_cgroup(page); 2836 struct zone *uninitialized_var(zone); 2837 struct lruvec *lruvec; 2838 bool was_on_lru = false; 2839 bool anon; 2840 2841 lock_page_cgroup(pc); 2842 VM_BUG_ON_PAGE(PageCgroupUsed(pc), page); 2843 /* 2844 * we don't need page_cgroup_lock about tail pages, becase they are not 2845 * accessed by any other context at this point. 2846 */ 2847 2848 /* 2849 * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page 2850 * may already be on some other mem_cgroup's LRU. Take care of it. 2851 */ 2852 if (lrucare) { 2853 zone = page_zone(page); 2854 spin_lock_irq(&zone->lru_lock); 2855 if (PageLRU(page)) { 2856 lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup); 2857 ClearPageLRU(page); 2858 del_page_from_lru_list(page, lruvec, page_lru(page)); 2859 was_on_lru = true; 2860 } 2861 } 2862 2863 pc->mem_cgroup = memcg; 2864 /* 2865 * We access a page_cgroup asynchronously without lock_page_cgroup(). 2866 * Especially when a page_cgroup is taken from a page, pc->mem_cgroup 2867 * is accessed after testing USED bit. To make pc->mem_cgroup visible 2868 * before USED bit, we need memory barrier here. 2869 * See mem_cgroup_add_lru_list(), etc. 2870 */ 2871 smp_wmb(); 2872 SetPageCgroupUsed(pc); 2873 2874 if (lrucare) { 2875 if (was_on_lru) { 2876 lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup); 2877 VM_BUG_ON_PAGE(PageLRU(page), page); 2878 SetPageLRU(page); 2879 add_page_to_lru_list(page, lruvec, page_lru(page)); 2880 } 2881 spin_unlock_irq(&zone->lru_lock); 2882 } 2883 2884 if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON) 2885 anon = true; 2886 else 2887 anon = false; 2888 2889 mem_cgroup_charge_statistics(memcg, page, anon, nr_pages); 2890 unlock_page_cgroup(pc); 2891 2892 /* 2893 * "charge_statistics" updated event counter. Then, check it. 2894 * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree. 2895 * if they exceeds softlimit. 2896 */ 2897 memcg_check_events(memcg, page); 2898 } 2899 2900 static DEFINE_MUTEX(set_limit_mutex); 2901 2902 #ifdef CONFIG_MEMCG_KMEM 2903 /* 2904 * The memcg_slab_mutex is held whenever a per memcg kmem cache is created or 2905 * destroyed. It protects memcg_caches arrays and memcg_slab_caches lists. 2906 */ 2907 static DEFINE_MUTEX(memcg_slab_mutex); 2908 2909 static DEFINE_MUTEX(activate_kmem_mutex); 2910 2911 static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg) 2912 { 2913 return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) && 2914 memcg_kmem_is_active(memcg); 2915 } 2916 2917 /* 2918 * This is a bit cumbersome, but it is rarely used and avoids a backpointer 2919 * in the memcg_cache_params struct. 2920 */ 2921 static struct kmem_cache *memcg_params_to_cache(struct memcg_cache_params *p) 2922 { 2923 struct kmem_cache *cachep; 2924 2925 VM_BUG_ON(p->is_root_cache); 2926 cachep = p->root_cache; 2927 return cache_from_memcg_idx(cachep, memcg_cache_id(p->memcg)); 2928 } 2929 2930 #ifdef CONFIG_SLABINFO 2931 static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v) 2932 { 2933 struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); 2934 struct memcg_cache_params *params; 2935 2936 if (!memcg_can_account_kmem(memcg)) 2937 return -EIO; 2938 2939 print_slabinfo_header(m); 2940 2941 mutex_lock(&memcg_slab_mutex); 2942 list_for_each_entry(params, &memcg->memcg_slab_caches, list) 2943 cache_show(memcg_params_to_cache(params), m); 2944 mutex_unlock(&memcg_slab_mutex); 2945 2946 return 0; 2947 } 2948 #endif 2949 2950 static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size) 2951 { 2952 struct res_counter *fail_res; 2953 int ret = 0; 2954 2955 ret = res_counter_charge(&memcg->kmem, size, &fail_res); 2956 if (ret) 2957 return ret; 2958 2959 ret = mem_cgroup_try_charge(memcg, gfp, size >> PAGE_SHIFT, 2960 oom_gfp_allowed(gfp)); 2961 if (ret == -EINTR) { 2962 /* 2963 * mem_cgroup_try_charge() chosed to bypass to root due to 2964 * OOM kill or fatal signal. Since our only options are to 2965 * either fail the allocation or charge it to this cgroup, do 2966 * it as a temporary condition. But we can't fail. From a 2967 * kmem/slab perspective, the cache has already been selected, 2968 * by mem_cgroup_kmem_get_cache(), so it is too late to change 2969 * our minds. 2970 * 2971 * This condition will only trigger if the task entered 2972 * memcg_charge_kmem in a sane state, but was OOM-killed during 2973 * mem_cgroup_try_charge() above. Tasks that were already 2974 * dying when the allocation triggers should have been already 2975 * directed to the root cgroup in memcontrol.h 2976 */ 2977 res_counter_charge_nofail(&memcg->res, size, &fail_res); 2978 if (do_swap_account) 2979 res_counter_charge_nofail(&memcg->memsw, size, 2980 &fail_res); 2981 ret = 0; 2982 } else if (ret) 2983 res_counter_uncharge(&memcg->kmem, size); 2984 2985 return ret; 2986 } 2987 2988 static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size) 2989 { 2990 res_counter_uncharge(&memcg->res, size); 2991 if (do_swap_account) 2992 res_counter_uncharge(&memcg->memsw, size); 2993 2994 /* Not down to 0 */ 2995 if (res_counter_uncharge(&memcg->kmem, size)) 2996 return; 2997 2998 /* 2999 * Releases a reference taken in kmem_cgroup_css_offline in case 3000 * this last uncharge is racing with the offlining code or it is 3001 * outliving the memcg existence. 3002 * 3003 * The memory barrier imposed by test&clear is paired with the 3004 * explicit one in memcg_kmem_mark_dead(). 3005 */ 3006 if (memcg_kmem_test_and_clear_dead(memcg)) 3007 css_put(&memcg->css); 3008 } 3009 3010 /* 3011 * helper for acessing a memcg's index. It will be used as an index in the 3012 * child cache array in kmem_cache, and also to derive its name. This function 3013 * will return -1 when this is not a kmem-limited memcg. 3014 */ 3015 int memcg_cache_id(struct mem_cgroup *memcg) 3016 { 3017 return memcg ? memcg->kmemcg_id : -1; 3018 } 3019 3020 static size_t memcg_caches_array_size(int num_groups) 3021 { 3022 ssize_t size; 3023 if (num_groups <= 0) 3024 return 0; 3025 3026 size = 2 * num_groups; 3027 if (size < MEMCG_CACHES_MIN_SIZE) 3028 size = MEMCG_CACHES_MIN_SIZE; 3029 else if (size > MEMCG_CACHES_MAX_SIZE) 3030 size = MEMCG_CACHES_MAX_SIZE; 3031 3032 return size; 3033 } 3034 3035 /* 3036 * We should update the current array size iff all caches updates succeed. This 3037 * can only be done from the slab side. The slab mutex needs to be held when 3038 * calling this. 3039 */ 3040 void memcg_update_array_size(int num) 3041 { 3042 if (num > memcg_limited_groups_array_size) 3043 memcg_limited_groups_array_size = memcg_caches_array_size(num); 3044 } 3045 3046 int memcg_update_cache_size(struct kmem_cache *s, int num_groups) 3047 { 3048 struct memcg_cache_params *cur_params = s->memcg_params; 3049 3050 VM_BUG_ON(!is_root_cache(s)); 3051 3052 if (num_groups > memcg_limited_groups_array_size) { 3053 int i; 3054 struct memcg_cache_params *new_params; 3055 ssize_t size = memcg_caches_array_size(num_groups); 3056 3057 size *= sizeof(void *); 3058 size += offsetof(struct memcg_cache_params, memcg_caches); 3059 3060 new_params = kzalloc(size, GFP_KERNEL); 3061 if (!new_params) 3062 return -ENOMEM; 3063 3064 new_params->is_root_cache = true; 3065 3066 /* 3067 * There is the chance it will be bigger than 3068 * memcg_limited_groups_array_size, if we failed an allocation 3069 * in a cache, in which case all caches updated before it, will 3070 * have a bigger array. 3071 * 3072 * But if that is the case, the data after 3073 * memcg_limited_groups_array_size is certainly unused 3074 */ 3075 for (i = 0; i < memcg_limited_groups_array_size; i++) { 3076 if (!cur_params->memcg_caches[i]) 3077 continue; 3078 new_params->memcg_caches[i] = 3079 cur_params->memcg_caches[i]; 3080 } 3081 3082 /* 3083 * Ideally, we would wait until all caches succeed, and only 3084 * then free the old one. But this is not worth the extra 3085 * pointer per-cache we'd have to have for this. 3086 * 3087 * It is not a big deal if some caches are left with a size 3088 * bigger than the others. And all updates will reset this 3089 * anyway. 3090 */ 3091 rcu_assign_pointer(s->memcg_params, new_params); 3092 if (cur_params) 3093 kfree_rcu(cur_params, rcu_head); 3094 } 3095 return 0; 3096 } 3097 3098 int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s, 3099 struct kmem_cache *root_cache) 3100 { 3101 size_t size; 3102 3103 if (!memcg_kmem_enabled()) 3104 return 0; 3105 3106 if (!memcg) { 3107 size = offsetof(struct memcg_cache_params, memcg_caches); 3108 size += memcg_limited_groups_array_size * sizeof(void *); 3109 } else 3110 size = sizeof(struct memcg_cache_params); 3111 3112 s->memcg_params = kzalloc(size, GFP_KERNEL); 3113 if (!s->memcg_params) 3114 return -ENOMEM; 3115 3116 if (memcg) { 3117 s->memcg_params->memcg = memcg; 3118 s->memcg_params->root_cache = root_cache; 3119 css_get(&memcg->css); 3120 } else 3121 s->memcg_params->is_root_cache = true; 3122 3123 return 0; 3124 } 3125 3126 void memcg_free_cache_params(struct kmem_cache *s) 3127 { 3128 if (!s->memcg_params) 3129 return; 3130 if (!s->memcg_params->is_root_cache) 3131 css_put(&s->memcg_params->memcg->css); 3132 kfree(s->memcg_params); 3133 } 3134 3135 static void memcg_register_cache(struct mem_cgroup *memcg, 3136 struct kmem_cache *root_cache) 3137 { 3138 static char memcg_name_buf[NAME_MAX + 1]; /* protected by 3139 memcg_slab_mutex */ 3140 struct kmem_cache *cachep; 3141 int id; 3142 3143 lockdep_assert_held(&memcg_slab_mutex); 3144 3145 id = memcg_cache_id(memcg); 3146 3147 /* 3148 * Since per-memcg caches are created asynchronously on first 3149 * allocation (see memcg_kmem_get_cache()), several threads can try to 3150 * create the same cache, but only one of them may succeed. 3151 */ 3152 if (cache_from_memcg_idx(root_cache, id)) 3153 return; 3154 3155 cgroup_name(memcg->css.cgroup, memcg_name_buf, NAME_MAX + 1); 3156 cachep = memcg_create_kmem_cache(memcg, root_cache, memcg_name_buf); 3157 /* 3158 * If we could not create a memcg cache, do not complain, because 3159 * that's not critical at all as we can always proceed with the root 3160 * cache. 3161 */ 3162 if (!cachep) 3163 return; 3164 3165 list_add(&cachep->memcg_params->list, &memcg->memcg_slab_caches); 3166 3167 /* 3168 * Since readers won't lock (see cache_from_memcg_idx()), we need a 3169 * barrier here to ensure nobody will see the kmem_cache partially 3170 * initialized. 3171 */ 3172 smp_wmb(); 3173 3174 BUG_ON(root_cache->memcg_params->memcg_caches[id]); 3175 root_cache->memcg_params->memcg_caches[id] = cachep; 3176 } 3177 3178 static void memcg_unregister_cache(struct kmem_cache *cachep) 3179 { 3180 struct kmem_cache *root_cache; 3181 struct mem_cgroup *memcg; 3182 int id; 3183 3184 lockdep_assert_held(&memcg_slab_mutex); 3185 3186 BUG_ON(is_root_cache(cachep)); 3187 3188 root_cache = cachep->memcg_params->root_cache; 3189 memcg = cachep->memcg_params->memcg; 3190 id = memcg_cache_id(memcg); 3191 3192 BUG_ON(root_cache->memcg_params->memcg_caches[id] != cachep); 3193 root_cache->memcg_params->memcg_caches[id] = NULL; 3194 3195 list_del(&cachep->memcg_params->list); 3196 3197 kmem_cache_destroy(cachep); 3198 } 3199 3200 /* 3201 * During the creation a new cache, we need to disable our accounting mechanism 3202 * altogether. This is true even if we are not creating, but rather just 3203 * enqueing new caches to be created. 3204 * 3205 * This is because that process will trigger allocations; some visible, like 3206 * explicit kmallocs to auxiliary data structures, name strings and internal 3207 * cache structures; some well concealed, like INIT_WORK() that can allocate 3208 * objects during debug. 3209 * 3210 * If any allocation happens during memcg_kmem_get_cache, we will recurse back 3211 * to it. This may not be a bounded recursion: since the first cache creation 3212 * failed to complete (waiting on the allocation), we'll just try to create the 3213 * cache again, failing at the same point. 3214 * 3215 * memcg_kmem_get_cache is prepared to abort after seeing a positive count of 3216 * memcg_kmem_skip_account. So we enclose anything that might allocate memory 3217 * inside the following two functions. 3218 */ 3219 static inline void memcg_stop_kmem_account(void) 3220 { 3221 VM_BUG_ON(!current->mm); 3222 current->memcg_kmem_skip_account++; 3223 } 3224 3225 static inline void memcg_resume_kmem_account(void) 3226 { 3227 VM_BUG_ON(!current->mm); 3228 current->memcg_kmem_skip_account--; 3229 } 3230 3231 int __memcg_cleanup_cache_params(struct kmem_cache *s) 3232 { 3233 struct kmem_cache *c; 3234 int i, failed = 0; 3235 3236 mutex_lock(&memcg_slab_mutex); 3237 for_each_memcg_cache_index(i) { 3238 c = cache_from_memcg_idx(s, i); 3239 if (!c) 3240 continue; 3241 3242 memcg_unregister_cache(c); 3243 3244 if (cache_from_memcg_idx(s, i)) 3245 failed++; 3246 } 3247 mutex_unlock(&memcg_slab_mutex); 3248 return failed; 3249 } 3250 3251 static void memcg_unregister_all_caches(struct mem_cgroup *memcg) 3252 { 3253 struct kmem_cache *cachep; 3254 struct memcg_cache_params *params, *tmp; 3255 3256 if (!memcg_kmem_is_active(memcg)) 3257 return; 3258 3259 mutex_lock(&memcg_slab_mutex); 3260 list_for_each_entry_safe(params, tmp, &memcg->memcg_slab_caches, list) { 3261 cachep = memcg_params_to_cache(params); 3262 kmem_cache_shrink(cachep); 3263 if (atomic_read(&cachep->memcg_params->nr_pages) == 0) 3264 memcg_unregister_cache(cachep); 3265 } 3266 mutex_unlock(&memcg_slab_mutex); 3267 } 3268 3269 struct memcg_register_cache_work { 3270 struct mem_cgroup *memcg; 3271 struct kmem_cache *cachep; 3272 struct work_struct work; 3273 }; 3274 3275 static void memcg_register_cache_func(struct work_struct *w) 3276 { 3277 struct memcg_register_cache_work *cw = 3278 container_of(w, struct memcg_register_cache_work, work); 3279 struct mem_cgroup *memcg = cw->memcg; 3280 struct kmem_cache *cachep = cw->cachep; 3281 3282 mutex_lock(&memcg_slab_mutex); 3283 memcg_register_cache(memcg, cachep); 3284 mutex_unlock(&memcg_slab_mutex); 3285 3286 css_put(&memcg->css); 3287 kfree(cw); 3288 } 3289 3290 /* 3291 * Enqueue the creation of a per-memcg kmem_cache. 3292 */ 3293 static void __memcg_schedule_register_cache(struct mem_cgroup *memcg, 3294 struct kmem_cache *cachep) 3295 { 3296 struct memcg_register_cache_work *cw; 3297 3298 cw = kmalloc(sizeof(*cw), GFP_NOWAIT); 3299 if (cw == NULL) { 3300 css_put(&memcg->css); 3301 return; 3302 } 3303 3304 cw->memcg = memcg; 3305 cw->cachep = cachep; 3306 3307 INIT_WORK(&cw->work, memcg_register_cache_func); 3308 schedule_work(&cw->work); 3309 } 3310 3311 static void memcg_schedule_register_cache(struct mem_cgroup *memcg, 3312 struct kmem_cache *cachep) 3313 { 3314 /* 3315 * We need to stop accounting when we kmalloc, because if the 3316 * corresponding kmalloc cache is not yet created, the first allocation 3317 * in __memcg_schedule_register_cache will recurse. 3318 * 3319 * However, it is better to enclose the whole function. Depending on 3320 * the debugging options enabled, INIT_WORK(), for instance, can 3321 * trigger an allocation. This too, will make us recurse. Because at 3322 * this point we can't allow ourselves back into memcg_kmem_get_cache, 3323 * the safest choice is to do it like this, wrapping the whole function. 3324 */ 3325 memcg_stop_kmem_account(); 3326 __memcg_schedule_register_cache(memcg, cachep); 3327 memcg_resume_kmem_account(); 3328 } 3329 3330 int __memcg_charge_slab(struct kmem_cache *cachep, gfp_t gfp, int order) 3331 { 3332 int res; 3333 3334 res = memcg_charge_kmem(cachep->memcg_params->memcg, gfp, 3335 PAGE_SIZE << order); 3336 if (!res) 3337 atomic_add(1 << order, &cachep->memcg_params->nr_pages); 3338 return res; 3339 } 3340 3341 void __memcg_uncharge_slab(struct kmem_cache *cachep, int order) 3342 { 3343 memcg_uncharge_kmem(cachep->memcg_params->memcg, PAGE_SIZE << order); 3344 atomic_sub(1 << order, &cachep->memcg_params->nr_pages); 3345 } 3346 3347 /* 3348 * Return the kmem_cache we're supposed to use for a slab allocation. 3349 * We try to use the current memcg's version of the cache. 3350 * 3351 * If the cache does not exist yet, if we are the first user of it, 3352 * we either create it immediately, if possible, or create it asynchronously 3353 * in a workqueue. 3354 * In the latter case, we will let the current allocation go through with 3355 * the original cache. 3356 * 3357 * Can't be called in interrupt context or from kernel threads. 3358 * This function needs to be called with rcu_read_lock() held. 3359 */ 3360 struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, 3361 gfp_t gfp) 3362 { 3363 struct mem_cgroup *memcg; 3364 struct kmem_cache *memcg_cachep; 3365 3366 VM_BUG_ON(!cachep->memcg_params); 3367 VM_BUG_ON(!cachep->memcg_params->is_root_cache); 3368 3369 if (!current->mm || current->memcg_kmem_skip_account) 3370 return cachep; 3371 3372 rcu_read_lock(); 3373 memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner)); 3374 3375 if (!memcg_can_account_kmem(memcg)) 3376 goto out; 3377 3378 memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg)); 3379 if (likely(memcg_cachep)) { 3380 cachep = memcg_cachep; 3381 goto out; 3382 } 3383 3384 /* The corresponding put will be done in the workqueue. */ 3385 if (!css_tryget(&memcg->css)) 3386 goto out; 3387 rcu_read_unlock(); 3388 3389 /* 3390 * If we are in a safe context (can wait, and not in interrupt 3391 * context), we could be be predictable and return right away. 3392 * This would guarantee that the allocation being performed 3393 * already belongs in the new cache. 3394 * 3395 * However, there are some clashes that can arrive from locking. 3396 * For instance, because we acquire the slab_mutex while doing 3397 * memcg_create_kmem_cache, this means no further allocation 3398 * could happen with the slab_mutex held. So it's better to 3399 * defer everything. 3400 */ 3401 memcg_schedule_register_cache(memcg, cachep); 3402 return cachep; 3403 out: 3404 rcu_read_unlock(); 3405 return cachep; 3406 } 3407 3408 /* 3409 * We need to verify if the allocation against current->mm->owner's memcg is 3410 * possible for the given order. But the page is not allocated yet, so we'll 3411 * need a further commit step to do the final arrangements. 3412 * 3413 * It is possible for the task to switch cgroups in this mean time, so at 3414 * commit time, we can't rely on task conversion any longer. We'll then use 3415 * the handle argument to return to the caller which cgroup we should commit 3416 * against. We could also return the memcg directly and avoid the pointer 3417 * passing, but a boolean return value gives better semantics considering 3418 * the compiled-out case as well. 3419 * 3420 * Returning true means the allocation is possible. 3421 */ 3422 bool 3423 __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order) 3424 { 3425 struct mem_cgroup *memcg; 3426 int ret; 3427 3428 *_memcg = NULL; 3429 3430 /* 3431 * Disabling accounting is only relevant for some specific memcg 3432 * internal allocations. Therefore we would initially not have such 3433 * check here, since direct calls to the page allocator that are 3434 * accounted to kmemcg (alloc_kmem_pages and friends) only happen 3435 * outside memcg core. We are mostly concerned with cache allocations, 3436 * and by having this test at memcg_kmem_get_cache, we are already able 3437 * to relay the allocation to the root cache and bypass the memcg cache 3438 * altogether. 3439 * 3440 * There is one exception, though: the SLUB allocator does not create 3441 * large order caches, but rather service large kmallocs directly from 3442 * the page allocator. Therefore, the following sequence when backed by 3443 * the SLUB allocator: 3444 * 3445 * memcg_stop_kmem_account(); 3446 * kmalloc(<large_number>) 3447 * memcg_resume_kmem_account(); 3448 * 3449 * would effectively ignore the fact that we should skip accounting, 3450 * since it will drive us directly to this function without passing 3451 * through the cache selector memcg_kmem_get_cache. Such large 3452 * allocations are extremely rare but can happen, for instance, for the 3453 * cache arrays. We bring this test here. 3454 */ 3455 if (!current->mm || current->memcg_kmem_skip_account) 3456 return true; 3457 3458 memcg = get_mem_cgroup_from_mm(current->mm); 3459 3460 if (!memcg_can_account_kmem(memcg)) { 3461 css_put(&memcg->css); 3462 return true; 3463 } 3464 3465 ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order); 3466 if (!ret) 3467 *_memcg = memcg; 3468 3469 css_put(&memcg->css); 3470 return (ret == 0); 3471 } 3472 3473 void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, 3474 int order) 3475 { 3476 struct page_cgroup *pc; 3477 3478 VM_BUG_ON(mem_cgroup_is_root(memcg)); 3479 3480 /* The page allocation failed. Revert */ 3481 if (!page) { 3482 memcg_uncharge_kmem(memcg, PAGE_SIZE << order); 3483 return; 3484 } 3485 3486 pc = lookup_page_cgroup(page); 3487 lock_page_cgroup(pc); 3488 pc->mem_cgroup = memcg; 3489 SetPageCgroupUsed(pc); 3490 unlock_page_cgroup(pc); 3491 } 3492 3493 void __memcg_kmem_uncharge_pages(struct page *page, int order) 3494 { 3495 struct mem_cgroup *memcg = NULL; 3496 struct page_cgroup *pc; 3497 3498 3499 pc = lookup_page_cgroup(page); 3500 /* 3501 * Fast unlocked return. Theoretically might have changed, have to 3502 * check again after locking. 3503 */ 3504 if (!PageCgroupUsed(pc)) 3505 return; 3506 3507 lock_page_cgroup(pc); 3508 if (PageCgroupUsed(pc)) { 3509 memcg = pc->mem_cgroup; 3510 ClearPageCgroupUsed(pc); 3511 } 3512 unlock_page_cgroup(pc); 3513 3514 /* 3515 * We trust that only if there is a memcg associated with the page, it 3516 * is a valid allocation 3517 */ 3518 if (!memcg) 3519 return; 3520 3521 VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page); 3522 memcg_uncharge_kmem(memcg, PAGE_SIZE << order); 3523 } 3524 #else 3525 static inline void memcg_unregister_all_caches(struct mem_cgroup *memcg) 3526 { 3527 } 3528 #endif /* CONFIG_MEMCG_KMEM */ 3529 3530 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 3531 3532 #define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION) 3533 /* 3534 * Because tail pages are not marked as "used", set it. We're under 3535 * zone->lru_lock, 'splitting on pmd' and compound_lock. 3536 * charge/uncharge will be never happen and move_account() is done under 3537 * compound_lock(), so we don't have to take care of races. 3538 */ 3539 void mem_cgroup_split_huge_fixup(struct page *head) 3540 { 3541 struct page_cgroup *head_pc = lookup_page_cgroup(head); 3542 struct page_cgroup *pc; 3543 struct mem_cgroup *memcg; 3544 int i; 3545 3546 if (mem_cgroup_disabled()) 3547 return; 3548 3549 memcg = head_pc->mem_cgroup; 3550 for (i = 1; i < HPAGE_PMD_NR; i++) { 3551 pc = head_pc + i; 3552 pc->mem_cgroup = memcg; 3553 smp_wmb();/* see __commit_charge() */ 3554 pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT; 3555 } 3556 __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], 3557 HPAGE_PMD_NR); 3558 } 3559 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 3560 3561 /** 3562 * mem_cgroup_move_account - move account of the page 3563 * @page: the page 3564 * @nr_pages: number of regular pages (>1 for huge pages) 3565 * @pc: page_cgroup of the page. 3566 * @from: mem_cgroup which the page is moved from. 3567 * @to: mem_cgroup which the page is moved to. @from != @to. 3568 * 3569 * The caller must confirm following. 3570 * - page is not on LRU (isolate_page() is useful.) 3571 * - compound_lock is held when nr_pages > 1 3572 * 3573 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge" 3574 * from old cgroup. 3575 */ 3576 static int mem_cgroup_move_account(struct page *page, 3577 unsigned int nr_pages, 3578 struct page_cgroup *pc, 3579 struct mem_cgroup *from, 3580 struct mem_cgroup *to) 3581 { 3582 unsigned long flags; 3583 int ret; 3584 bool anon = PageAnon(page); 3585 3586 VM_BUG_ON(from == to); 3587 VM_BUG_ON_PAGE(PageLRU(page), page); 3588 /* 3589 * The page is isolated from LRU. So, collapse function 3590 * will not handle this page. But page splitting can happen. 3591 * Do this check under compound_page_lock(). The caller should 3592 * hold it. 3593 */ 3594 ret = -EBUSY; 3595 if (nr_pages > 1 && !PageTransHuge(page)) 3596 goto out; 3597 3598 lock_page_cgroup(pc); 3599 3600 ret = -EINVAL; 3601 if (!PageCgroupUsed(pc) || pc->mem_cgroup != from) 3602 goto unlock; 3603 3604 move_lock_mem_cgroup(from, &flags); 3605 3606 if (!anon && page_mapped(page)) { 3607 __this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED], 3608 nr_pages); 3609 __this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED], 3610 nr_pages); 3611 } 3612 3613 if (PageWriteback(page)) { 3614 __this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK], 3615 nr_pages); 3616 __this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK], 3617 nr_pages); 3618 } 3619 3620 mem_cgroup_charge_statistics(from, page, anon, -nr_pages); 3621 3622 /* caller should have done css_get */ 3623 pc->mem_cgroup = to; 3624 mem_cgroup_charge_statistics(to, page, anon, nr_pages); 3625 move_unlock_mem_cgroup(from, &flags); 3626 ret = 0; 3627 unlock: 3628 unlock_page_cgroup(pc); 3629 /* 3630 * check events 3631 */ 3632 memcg_check_events(to, page); 3633 memcg_check_events(from, page); 3634 out: 3635 return ret; 3636 } 3637 3638 /** 3639 * mem_cgroup_move_parent - moves page to the parent group 3640 * @page: the page to move 3641 * @pc: page_cgroup of the page 3642 * @child: page's cgroup 3643 * 3644 * move charges to its parent or the root cgroup if the group has no 3645 * parent (aka use_hierarchy==0). 3646 * Although this might fail (get_page_unless_zero, isolate_lru_page or 3647 * mem_cgroup_move_account fails) the failure is always temporary and 3648 * it signals a race with a page removal/uncharge or migration. In the 3649 * first case the page is on the way out and it will vanish from the LRU 3650 * on the next attempt and the call should be retried later. 3651 * Isolation from the LRU fails only if page has been isolated from 3652 * the LRU since we looked at it and that usually means either global 3653 * reclaim or migration going on. The page will either get back to the 3654 * LRU or vanish. 3655 * Finaly mem_cgroup_move_account fails only if the page got uncharged 3656 * (!PageCgroupUsed) or moved to a different group. The page will 3657 * disappear in the next attempt. 3658 */ 3659 static int mem_cgroup_move_parent(struct page *page, 3660 struct page_cgroup *pc, 3661 struct mem_cgroup *child) 3662 { 3663 struct mem_cgroup *parent; 3664 unsigned int nr_pages; 3665 unsigned long uninitialized_var(flags); 3666 int ret; 3667 3668 VM_BUG_ON(mem_cgroup_is_root(child)); 3669 3670 ret = -EBUSY; 3671 if (!get_page_unless_zero(page)) 3672 goto out; 3673 if (isolate_lru_page(page)) 3674 goto put; 3675 3676 nr_pages = hpage_nr_pages(page); 3677 3678 parent = parent_mem_cgroup(child); 3679 /* 3680 * If no parent, move charges to root cgroup. 3681 */ 3682 if (!parent) 3683 parent = root_mem_cgroup; 3684 3685 if (nr_pages > 1) { 3686 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 3687 flags = compound_lock_irqsave(page); 3688 } 3689 3690 ret = mem_cgroup_move_account(page, nr_pages, 3691 pc, child, parent); 3692 if (!ret) 3693 __mem_cgroup_cancel_local_charge(child, nr_pages); 3694 3695 if (nr_pages > 1) 3696 compound_unlock_irqrestore(page, flags); 3697 putback_lru_page(page); 3698 put: 3699 put_page(page); 3700 out: 3701 return ret; 3702 } 3703 3704 int mem_cgroup_charge_anon(struct page *page, 3705 struct mm_struct *mm, gfp_t gfp_mask) 3706 { 3707 unsigned int nr_pages = 1; 3708 struct mem_cgroup *memcg; 3709 bool oom = true; 3710 3711 if (mem_cgroup_disabled()) 3712 return 0; 3713 3714 VM_BUG_ON_PAGE(page_mapped(page), page); 3715 VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page); 3716 VM_BUG_ON(!mm); 3717 3718 if (PageTransHuge(page)) { 3719 nr_pages <<= compound_order(page); 3720 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 3721 /* 3722 * Never OOM-kill a process for a huge page. The 3723 * fault handler will fall back to regular pages. 3724 */ 3725 oom = false; 3726 } 3727 3728 memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom); 3729 if (!memcg) 3730 return -ENOMEM; 3731 __mem_cgroup_commit_charge(memcg, page, nr_pages, 3732 MEM_CGROUP_CHARGE_TYPE_ANON, false); 3733 return 0; 3734 } 3735 3736 /* 3737 * While swap-in, try_charge -> commit or cancel, the page is locked. 3738 * And when try_charge() successfully returns, one refcnt to memcg without 3739 * struct page_cgroup is acquired. This refcnt will be consumed by 3740 * "commit()" or removed by "cancel()" 3741 */ 3742 static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm, 3743 struct page *page, 3744 gfp_t mask, 3745 struct mem_cgroup **memcgp) 3746 { 3747 struct mem_cgroup *memcg = NULL; 3748 struct page_cgroup *pc; 3749 int ret; 3750 3751 pc = lookup_page_cgroup(page); 3752 /* 3753 * Every swap fault against a single page tries to charge the 3754 * page, bail as early as possible. shmem_unuse() encounters 3755 * already charged pages, too. The USED bit is protected by 3756 * the page lock, which serializes swap cache removal, which 3757 * in turn serializes uncharging. 3758 */ 3759 if (PageCgroupUsed(pc)) 3760 goto out; 3761 if (do_swap_account) 3762 memcg = try_get_mem_cgroup_from_page(page); 3763 if (!memcg) 3764 memcg = get_mem_cgroup_from_mm(mm); 3765 ret = mem_cgroup_try_charge(memcg, mask, 1, true); 3766 css_put(&memcg->css); 3767 if (ret == -EINTR) 3768 memcg = root_mem_cgroup; 3769 else if (ret) 3770 return ret; 3771 out: 3772 *memcgp = memcg; 3773 return 0; 3774 } 3775 3776 int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page, 3777 gfp_t gfp_mask, struct mem_cgroup **memcgp) 3778 { 3779 if (mem_cgroup_disabled()) { 3780 *memcgp = NULL; 3781 return 0; 3782 } 3783 /* 3784 * A racing thread's fault, or swapoff, may have already 3785 * updated the pte, and even removed page from swap cache: in 3786 * those cases unuse_pte()'s pte_same() test will fail; but 3787 * there's also a KSM case which does need to charge the page. 3788 */ 3789 if (!PageSwapCache(page)) { 3790 struct mem_cgroup *memcg; 3791 3792 memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true); 3793 if (!memcg) 3794 return -ENOMEM; 3795 *memcgp = memcg; 3796 return 0; 3797 } 3798 return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp); 3799 } 3800 3801 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg) 3802 { 3803 if (mem_cgroup_disabled()) 3804 return; 3805 if (!memcg) 3806 return; 3807 __mem_cgroup_cancel_charge(memcg, 1); 3808 } 3809 3810 static void 3811 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg, 3812 enum charge_type ctype) 3813 { 3814 if (mem_cgroup_disabled()) 3815 return; 3816 if (!memcg) 3817 return; 3818 3819 __mem_cgroup_commit_charge(memcg, page, 1, ctype, true); 3820 /* 3821 * Now swap is on-memory. This means this page may be 3822 * counted both as mem and swap....double count. 3823 * Fix it by uncharging from memsw. Basically, this SwapCache is stable 3824 * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page() 3825 * may call delete_from_swap_cache() before reach here. 3826 */ 3827 if (do_swap_account && PageSwapCache(page)) { 3828 swp_entry_t ent = {.val = page_private(page)}; 3829 mem_cgroup_uncharge_swap(ent); 3830 } 3831 } 3832 3833 void mem_cgroup_commit_charge_swapin(struct page *page, 3834 struct mem_cgroup *memcg) 3835 { 3836 __mem_cgroup_commit_charge_swapin(page, memcg, 3837 MEM_CGROUP_CHARGE_TYPE_ANON); 3838 } 3839 3840 int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm, 3841 gfp_t gfp_mask) 3842 { 3843 enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE; 3844 struct mem_cgroup *memcg; 3845 int ret; 3846 3847 if (mem_cgroup_disabled()) 3848 return 0; 3849 if (PageCompound(page)) 3850 return 0; 3851 3852 if (PageSwapCache(page)) { /* shmem */ 3853 ret = __mem_cgroup_try_charge_swapin(mm, page, 3854 gfp_mask, &memcg); 3855 if (ret) 3856 return ret; 3857 __mem_cgroup_commit_charge_swapin(page, memcg, type); 3858 return 0; 3859 } 3860 3861 memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true); 3862 if (!memcg) 3863 return -ENOMEM; 3864 __mem_cgroup_commit_charge(memcg, page, 1, type, false); 3865 return 0; 3866 } 3867 3868 static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg, 3869 unsigned int nr_pages, 3870 const enum charge_type ctype) 3871 { 3872 struct memcg_batch_info *batch = NULL; 3873 bool uncharge_memsw = true; 3874 3875 /* If swapout, usage of swap doesn't decrease */ 3876 if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) 3877 uncharge_memsw = false; 3878 3879 batch = ¤t->memcg_batch; 3880 /* 3881 * In usual, we do css_get() when we remember memcg pointer. 3882 * But in this case, we keep res->usage until end of a series of 3883 * uncharges. Then, it's ok to ignore memcg's refcnt. 3884 */ 3885 if (!batch->memcg) 3886 batch->memcg = memcg; 3887 /* 3888 * do_batch > 0 when unmapping pages or inode invalidate/truncate. 3889 * In those cases, all pages freed continuously can be expected to be in 3890 * the same cgroup and we have chance to coalesce uncharges. 3891 * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE) 3892 * because we want to do uncharge as soon as possible. 3893 */ 3894 3895 if (!batch->do_batch || test_thread_flag(TIF_MEMDIE)) 3896 goto direct_uncharge; 3897 3898 if (nr_pages > 1) 3899 goto direct_uncharge; 3900 3901 /* 3902 * In typical case, batch->memcg == mem. This means we can 3903 * merge a series of uncharges to an uncharge of res_counter. 3904 * If not, we uncharge res_counter ony by one. 3905 */ 3906 if (batch->memcg != memcg) 3907 goto direct_uncharge; 3908 /* remember freed charge and uncharge it later */ 3909 batch->nr_pages++; 3910 if (uncharge_memsw) 3911 batch->memsw_nr_pages++; 3912 return; 3913 direct_uncharge: 3914 res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE); 3915 if (uncharge_memsw) 3916 res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE); 3917 if (unlikely(batch->memcg != memcg)) 3918 memcg_oom_recover(memcg); 3919 } 3920 3921 /* 3922 * uncharge if !page_mapped(page) 3923 */ 3924 static struct mem_cgroup * 3925 __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype, 3926 bool end_migration) 3927 { 3928 struct mem_cgroup *memcg = NULL; 3929 unsigned int nr_pages = 1; 3930 struct page_cgroup *pc; 3931 bool anon; 3932 3933 if (mem_cgroup_disabled()) 3934 return NULL; 3935 3936 if (PageTransHuge(page)) { 3937 nr_pages <<= compound_order(page); 3938 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 3939 } 3940 /* 3941 * Check if our page_cgroup is valid 3942 */ 3943 pc = lookup_page_cgroup(page); 3944 if (unlikely(!PageCgroupUsed(pc))) 3945 return NULL; 3946 3947 lock_page_cgroup(pc); 3948 3949 memcg = pc->mem_cgroup; 3950 3951 if (!PageCgroupUsed(pc)) 3952 goto unlock_out; 3953 3954 anon = PageAnon(page); 3955 3956 switch (ctype) { 3957 case MEM_CGROUP_CHARGE_TYPE_ANON: 3958 /* 3959 * Generally PageAnon tells if it's the anon statistics to be 3960 * updated; but sometimes e.g. mem_cgroup_uncharge_page() is 3961 * used before page reached the stage of being marked PageAnon. 3962 */ 3963 anon = true; 3964 /* fallthrough */ 3965 case MEM_CGROUP_CHARGE_TYPE_DROP: 3966 /* See mem_cgroup_prepare_migration() */ 3967 if (page_mapped(page)) 3968 goto unlock_out; 3969 /* 3970 * Pages under migration may not be uncharged. But 3971 * end_migration() /must/ be the one uncharging the 3972 * unused post-migration page and so it has to call 3973 * here with the migration bit still set. See the 3974 * res_counter handling below. 3975 */ 3976 if (!end_migration && PageCgroupMigration(pc)) 3977 goto unlock_out; 3978 break; 3979 case MEM_CGROUP_CHARGE_TYPE_SWAPOUT: 3980 if (!PageAnon(page)) { /* Shared memory */ 3981 if (page->mapping && !page_is_file_cache(page)) 3982 goto unlock_out; 3983 } else if (page_mapped(page)) /* Anon */ 3984 goto unlock_out; 3985 break; 3986 default: 3987 break; 3988 } 3989 3990 mem_cgroup_charge_statistics(memcg, page, anon, -nr_pages); 3991 3992 ClearPageCgroupUsed(pc); 3993 /* 3994 * pc->mem_cgroup is not cleared here. It will be accessed when it's 3995 * freed from LRU. This is safe because uncharged page is expected not 3996 * to be reused (freed soon). Exception is SwapCache, it's handled by 3997 * special functions. 3998 */ 3999 4000 unlock_page_cgroup(pc); 4001 /* 4002 * even after unlock, we have memcg->res.usage here and this memcg 4003 * will never be freed, so it's safe to call css_get(). 4004 */ 4005 memcg_check_events(memcg, page); 4006 if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) { 4007 mem_cgroup_swap_statistics(memcg, true); 4008 css_get(&memcg->css); 4009 } 4010 /* 4011 * Migration does not charge the res_counter for the 4012 * replacement page, so leave it alone when phasing out the 4013 * page that is unused after the migration. 4014 */ 4015 if (!end_migration && !mem_cgroup_is_root(memcg)) 4016 mem_cgroup_do_uncharge(memcg, nr_pages, ctype); 4017 4018 return memcg; 4019 4020 unlock_out: 4021 unlock_page_cgroup(pc); 4022 return NULL; 4023 } 4024 4025 void mem_cgroup_uncharge_page(struct page *page) 4026 { 4027 /* early check. */ 4028 if (page_mapped(page)) 4029 return; 4030 VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page); 4031 /* 4032 * If the page is in swap cache, uncharge should be deferred 4033 * to the swap path, which also properly accounts swap usage 4034 * and handles memcg lifetime. 4035 * 4036 * Note that this check is not stable and reclaim may add the 4037 * page to swap cache at any time after this. However, if the 4038 * page is not in swap cache by the time page->mapcount hits 4039 * 0, there won't be any page table references to the swap 4040 * slot, and reclaim will free it and not actually write the 4041 * page to disk. 4042 */ 4043 if (PageSwapCache(page)) 4044 return; 4045 __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false); 4046 } 4047 4048 void mem_cgroup_uncharge_cache_page(struct page *page) 4049 { 4050 VM_BUG_ON_PAGE(page_mapped(page), page); 4051 VM_BUG_ON_PAGE(page->mapping, page); 4052 __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false); 4053 } 4054 4055 /* 4056 * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate. 4057 * In that cases, pages are freed continuously and we can expect pages 4058 * are in the same memcg. All these calls itself limits the number of 4059 * pages freed at once, then uncharge_start/end() is called properly. 4060 * This may be called prural(2) times in a context, 4061 */ 4062 4063 void mem_cgroup_uncharge_start(void) 4064 { 4065 current->memcg_batch.do_batch++; 4066 /* We can do nest. */ 4067 if (current->memcg_batch.do_batch == 1) { 4068 current->memcg_batch.memcg = NULL; 4069 current->memcg_batch.nr_pages = 0; 4070 current->memcg_batch.memsw_nr_pages = 0; 4071 } 4072 } 4073 4074 void mem_cgroup_uncharge_end(void) 4075 { 4076 struct memcg_batch_info *batch = ¤t->memcg_batch; 4077 4078 if (!batch->do_batch) 4079 return; 4080 4081 batch->do_batch--; 4082 if (batch->do_batch) /* If stacked, do nothing. */ 4083 return; 4084 4085 if (!batch->memcg) 4086 return; 4087 /* 4088 * This "batch->memcg" is valid without any css_get/put etc... 4089 * bacause we hide charges behind us. 4090 */ 4091 if (batch->nr_pages) 4092 res_counter_uncharge(&batch->memcg->res, 4093 batch->nr_pages * PAGE_SIZE); 4094 if (batch->memsw_nr_pages) 4095 res_counter_uncharge(&batch->memcg->memsw, 4096 batch->memsw_nr_pages * PAGE_SIZE); 4097 memcg_oom_recover(batch->memcg); 4098 /* forget this pointer (for sanity check) */ 4099 batch->memcg = NULL; 4100 } 4101 4102 #ifdef CONFIG_SWAP 4103 /* 4104 * called after __delete_from_swap_cache() and drop "page" account. 4105 * memcg information is recorded to swap_cgroup of "ent" 4106 */ 4107 void 4108 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) 4109 { 4110 struct mem_cgroup *memcg; 4111 int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT; 4112 4113 if (!swapout) /* this was a swap cache but the swap is unused ! */ 4114 ctype = MEM_CGROUP_CHARGE_TYPE_DROP; 4115 4116 memcg = __mem_cgroup_uncharge_common(page, ctype, false); 4117 4118 /* 4119 * record memcg information, if swapout && memcg != NULL, 4120 * css_get() was called in uncharge(). 4121 */ 4122 if (do_swap_account && swapout && memcg) 4123 swap_cgroup_record(ent, mem_cgroup_id(memcg)); 4124 } 4125 #endif 4126 4127 #ifdef CONFIG_MEMCG_SWAP 4128 /* 4129 * called from swap_entry_free(). remove record in swap_cgroup and 4130 * uncharge "memsw" account. 4131 */ 4132 void mem_cgroup_uncharge_swap(swp_entry_t ent) 4133 { 4134 struct mem_cgroup *memcg; 4135 unsigned short id; 4136 4137 if (!do_swap_account) 4138 return; 4139 4140 id = swap_cgroup_record(ent, 0); 4141 rcu_read_lock(); 4142 memcg = mem_cgroup_lookup(id); 4143 if (memcg) { 4144 /* 4145 * We uncharge this because swap is freed. 4146 * This memcg can be obsolete one. We avoid calling css_tryget 4147 */ 4148 if (!mem_cgroup_is_root(memcg)) 4149 res_counter_uncharge(&memcg->memsw, PAGE_SIZE); 4150 mem_cgroup_swap_statistics(memcg, false); 4151 css_put(&memcg->css); 4152 } 4153 rcu_read_unlock(); 4154 } 4155 4156 /** 4157 * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. 4158 * @entry: swap entry to be moved 4159 * @from: mem_cgroup which the entry is moved from 4160 * @to: mem_cgroup which the entry is moved to 4161 * 4162 * It succeeds only when the swap_cgroup's record for this entry is the same 4163 * as the mem_cgroup's id of @from. 4164 * 4165 * Returns 0 on success, -EINVAL on failure. 4166 * 4167 * The caller must have charged to @to, IOW, called res_counter_charge() about 4168 * both res and memsw, and called css_get(). 4169 */ 4170 static int mem_cgroup_move_swap_account(swp_entry_t entry, 4171 struct mem_cgroup *from, struct mem_cgroup *to) 4172 { 4173 unsigned short old_id, new_id; 4174 4175 old_id = mem_cgroup_id(from); 4176 new_id = mem_cgroup_id(to); 4177 4178 if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { 4179 mem_cgroup_swap_statistics(from, false); 4180 mem_cgroup_swap_statistics(to, true); 4181 /* 4182 * This function is only called from task migration context now. 4183 * It postpones res_counter and refcount handling till the end 4184 * of task migration(mem_cgroup_clear_mc()) for performance 4185 * improvement. But we cannot postpone css_get(to) because if 4186 * the process that has been moved to @to does swap-in, the 4187 * refcount of @to might be decreased to 0. 4188 * 4189 * We are in attach() phase, so the cgroup is guaranteed to be 4190 * alive, so we can just call css_get(). 4191 */ 4192 css_get(&to->css); 4193 return 0; 4194 } 4195 return -EINVAL; 4196 } 4197 #else 4198 static inline int mem_cgroup_move_swap_account(swp_entry_t entry, 4199 struct mem_cgroup *from, struct mem_cgroup *to) 4200 { 4201 return -EINVAL; 4202 } 4203 #endif 4204 4205 /* 4206 * Before starting migration, account PAGE_SIZE to mem_cgroup that the old 4207 * page belongs to. 4208 */ 4209 void mem_cgroup_prepare_migration(struct page *page, struct page *newpage, 4210 struct mem_cgroup **memcgp) 4211 { 4212 struct mem_cgroup *memcg = NULL; 4213 unsigned int nr_pages = 1; 4214 struct page_cgroup *pc; 4215 enum charge_type ctype; 4216 4217 *memcgp = NULL; 4218 4219 if (mem_cgroup_disabled()) 4220 return; 4221 4222 if (PageTransHuge(page)) 4223 nr_pages <<= compound_order(page); 4224 4225 pc = lookup_page_cgroup(page); 4226 lock_page_cgroup(pc); 4227 if (PageCgroupUsed(pc)) { 4228 memcg = pc->mem_cgroup; 4229 css_get(&memcg->css); 4230 /* 4231 * At migrating an anonymous page, its mapcount goes down 4232 * to 0 and uncharge() will be called. But, even if it's fully 4233 * unmapped, migration may fail and this page has to be 4234 * charged again. We set MIGRATION flag here and delay uncharge 4235 * until end_migration() is called 4236 * 4237 * Corner Case Thinking 4238 * A) 4239 * When the old page was mapped as Anon and it's unmap-and-freed 4240 * while migration was ongoing. 4241 * If unmap finds the old page, uncharge() of it will be delayed 4242 * until end_migration(). If unmap finds a new page, it's 4243 * uncharged when it make mapcount to be 1->0. If unmap code 4244 * finds swap_migration_entry, the new page will not be mapped 4245 * and end_migration() will find it(mapcount==0). 4246 * 4247 * B) 4248 * When the old page was mapped but migraion fails, the kernel 4249 * remaps it. A charge for it is kept by MIGRATION flag even 4250 * if mapcount goes down to 0. We can do remap successfully 4251 * without charging it again. 4252 * 4253 * C) 4254 * The "old" page is under lock_page() until the end of 4255 * migration, so, the old page itself will not be swapped-out. 4256 * If the new page is swapped out before end_migraton, our 4257 * hook to usual swap-out path will catch the event. 4258 */ 4259 if (PageAnon(page)) 4260 SetPageCgroupMigration(pc); 4261 } 4262 unlock_page_cgroup(pc); 4263 /* 4264 * If the page is not charged at this point, 4265 * we return here. 4266 */ 4267 if (!memcg) 4268 return; 4269 4270 *memcgp = memcg; 4271 /* 4272 * We charge new page before it's used/mapped. So, even if unlock_page() 4273 * is called before end_migration, we can catch all events on this new 4274 * page. In the case new page is migrated but not remapped, new page's 4275 * mapcount will be finally 0 and we call uncharge in end_migration(). 4276 */ 4277 if (PageAnon(page)) 4278 ctype = MEM_CGROUP_CHARGE_TYPE_ANON; 4279 else 4280 ctype = MEM_CGROUP_CHARGE_TYPE_CACHE; 4281 /* 4282 * The page is committed to the memcg, but it's not actually 4283 * charged to the res_counter since we plan on replacing the 4284 * old one and only one page is going to be left afterwards. 4285 */ 4286 __mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false); 4287 } 4288 4289 /* remove redundant charge if migration failed*/ 4290 void mem_cgroup_end_migration(struct mem_cgroup *memcg, 4291 struct page *oldpage, struct page *newpage, bool migration_ok) 4292 { 4293 struct page *used, *unused; 4294 struct page_cgroup *pc; 4295 bool anon; 4296 4297 if (!memcg) 4298 return; 4299 4300 if (!migration_ok) { 4301 used = oldpage; 4302 unused = newpage; 4303 } else { 4304 used = newpage; 4305 unused = oldpage; 4306 } 4307 anon = PageAnon(used); 4308 __mem_cgroup_uncharge_common(unused, 4309 anon ? MEM_CGROUP_CHARGE_TYPE_ANON 4310 : MEM_CGROUP_CHARGE_TYPE_CACHE, 4311 true); 4312 css_put(&memcg->css); 4313 /* 4314 * We disallowed uncharge of pages under migration because mapcount 4315 * of the page goes down to zero, temporarly. 4316 * Clear the flag and check the page should be charged. 4317 */ 4318 pc = lookup_page_cgroup(oldpage); 4319 lock_page_cgroup(pc); 4320 ClearPageCgroupMigration(pc); 4321 unlock_page_cgroup(pc); 4322 4323 /* 4324 * If a page is a file cache, radix-tree replacement is very atomic 4325 * and we can skip this check. When it was an Anon page, its mapcount 4326 * goes down to 0. But because we added MIGRATION flage, it's not 4327 * uncharged yet. There are several case but page->mapcount check 4328 * and USED bit check in mem_cgroup_uncharge_page() will do enough 4329 * check. (see prepare_charge() also) 4330 */ 4331 if (anon) 4332 mem_cgroup_uncharge_page(used); 4333 } 4334 4335 /* 4336 * At replace page cache, newpage is not under any memcg but it's on 4337 * LRU. So, this function doesn't touch res_counter but handles LRU 4338 * in correct way. Both pages are locked so we cannot race with uncharge. 4339 */ 4340 void mem_cgroup_replace_page_cache(struct page *oldpage, 4341 struct page *newpage) 4342 { 4343 struct mem_cgroup *memcg = NULL; 4344 struct page_cgroup *pc; 4345 enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE; 4346 4347 if (mem_cgroup_disabled()) 4348 return; 4349 4350 pc = lookup_page_cgroup(oldpage); 4351 /* fix accounting on old pages */ 4352 lock_page_cgroup(pc); 4353 if (PageCgroupUsed(pc)) { 4354 memcg = pc->mem_cgroup; 4355 mem_cgroup_charge_statistics(memcg, oldpage, false, -1); 4356 ClearPageCgroupUsed(pc); 4357 } 4358 unlock_page_cgroup(pc); 4359 4360 /* 4361 * When called from shmem_replace_page(), in some cases the 4362 * oldpage has already been charged, and in some cases not. 4363 */ 4364 if (!memcg) 4365 return; 4366 /* 4367 * Even if newpage->mapping was NULL before starting replacement, 4368 * the newpage may be on LRU(or pagevec for LRU) already. We lock 4369 * LRU while we overwrite pc->mem_cgroup. 4370 */ 4371 __mem_cgroup_commit_charge(memcg, newpage, 1, type, true); 4372 } 4373 4374 #ifdef CONFIG_DEBUG_VM 4375 static struct page_cgroup *lookup_page_cgroup_used(struct page *page) 4376 { 4377 struct page_cgroup *pc; 4378 4379 pc = lookup_page_cgroup(page); 4380 /* 4381 * Can be NULL while feeding pages into the page allocator for 4382 * the first time, i.e. during boot or memory hotplug; 4383 * or when mem_cgroup_disabled(). 4384 */ 4385 if (likely(pc) && PageCgroupUsed(pc)) 4386 return pc; 4387 return NULL; 4388 } 4389 4390 bool mem_cgroup_bad_page_check(struct page *page) 4391 { 4392 if (mem_cgroup_disabled()) 4393 return false; 4394 4395 return lookup_page_cgroup_used(page) != NULL; 4396 } 4397 4398 void mem_cgroup_print_bad_page(struct page *page) 4399 { 4400 struct page_cgroup *pc; 4401 4402 pc = lookup_page_cgroup_used(page); 4403 if (pc) { 4404 pr_alert("pc:%p pc->flags:%lx pc->mem_cgroup:%p\n", 4405 pc, pc->flags, pc->mem_cgroup); 4406 } 4407 } 4408 #endif 4409 4410 static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, 4411 unsigned long long val) 4412 { 4413 int retry_count; 4414 u64 memswlimit, memlimit; 4415 int ret = 0; 4416 int children = mem_cgroup_count_children(memcg); 4417 u64 curusage, oldusage; 4418 int enlarge; 4419 4420 /* 4421 * For keeping hierarchical_reclaim simple, how long we should retry 4422 * is depends on callers. We set our retry-count to be function 4423 * of # of children which we should visit in this loop. 4424 */ 4425 retry_count = MEM_CGROUP_RECLAIM_RETRIES * children; 4426 4427 oldusage = res_counter_read_u64(&memcg->res, RES_USAGE); 4428 4429 enlarge = 0; 4430 while (retry_count) { 4431 if (signal_pending(current)) { 4432 ret = -EINTR; 4433 break; 4434 } 4435 /* 4436 * Rather than hide all in some function, I do this in 4437 * open coded manner. You see what this really does. 4438 * We have to guarantee memcg->res.limit <= memcg->memsw.limit. 4439 */ 4440 mutex_lock(&set_limit_mutex); 4441 memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 4442 if (memswlimit < val) { 4443 ret = -EINVAL; 4444 mutex_unlock(&set_limit_mutex); 4445 break; 4446 } 4447 4448 memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT); 4449 if (memlimit < val) 4450 enlarge = 1; 4451 4452 ret = res_counter_set_limit(&memcg->res, val); 4453 if (!ret) { 4454 if (memswlimit == val) 4455 memcg->memsw_is_minimum = true; 4456 else 4457 memcg->memsw_is_minimum = false; 4458 } 4459 mutex_unlock(&set_limit_mutex); 4460 4461 if (!ret) 4462 break; 4463 4464 mem_cgroup_reclaim(memcg, GFP_KERNEL, 4465 MEM_CGROUP_RECLAIM_SHRINK); 4466 curusage = res_counter_read_u64(&memcg->res, RES_USAGE); 4467 /* Usage is reduced ? */ 4468 if (curusage >= oldusage) 4469 retry_count--; 4470 else 4471 oldusage = curusage; 4472 } 4473 if (!ret && enlarge) 4474 memcg_oom_recover(memcg); 4475 4476 return ret; 4477 } 4478 4479 static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, 4480 unsigned long long val) 4481 { 4482 int retry_count; 4483 u64 memlimit, memswlimit, oldusage, curusage; 4484 int children = mem_cgroup_count_children(memcg); 4485 int ret = -EBUSY; 4486 int enlarge = 0; 4487 4488 /* see mem_cgroup_resize_res_limit */ 4489 retry_count = children * MEM_CGROUP_RECLAIM_RETRIES; 4490 oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); 4491 while (retry_count) { 4492 if (signal_pending(current)) { 4493 ret = -EINTR; 4494 break; 4495 } 4496 /* 4497 * Rather than hide all in some function, I do this in 4498 * open coded manner. You see what this really does. 4499 * We have to guarantee memcg->res.limit <= memcg->memsw.limit. 4500 */ 4501 mutex_lock(&set_limit_mutex); 4502 memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT); 4503 if (memlimit > val) { 4504 ret = -EINVAL; 4505 mutex_unlock(&set_limit_mutex); 4506 break; 4507 } 4508 memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 4509 if (memswlimit < val) 4510 enlarge = 1; 4511 ret = res_counter_set_limit(&memcg->memsw, val); 4512 if (!ret) { 4513 if (memlimit == val) 4514 memcg->memsw_is_minimum = true; 4515 else 4516 memcg->memsw_is_minimum = false; 4517 } 4518 mutex_unlock(&set_limit_mutex); 4519 4520 if (!ret) 4521 break; 4522 4523 mem_cgroup_reclaim(memcg, GFP_KERNEL, 4524 MEM_CGROUP_RECLAIM_NOSWAP | 4525 MEM_CGROUP_RECLAIM_SHRINK); 4526 curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); 4527 /* Usage is reduced ? */ 4528 if (curusage >= oldusage) 4529 retry_count--; 4530 else 4531 oldusage = curusage; 4532 } 4533 if (!ret && enlarge) 4534 memcg_oom_recover(memcg); 4535 return ret; 4536 } 4537 4538 unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, 4539 gfp_t gfp_mask, 4540 unsigned long *total_scanned) 4541 { 4542 unsigned long nr_reclaimed = 0; 4543 struct mem_cgroup_per_zone *mz, *next_mz = NULL; 4544 unsigned long reclaimed; 4545 int loop = 0; 4546 struct mem_cgroup_tree_per_zone *mctz; 4547 unsigned long long excess; 4548 unsigned long nr_scanned; 4549 4550 if (order > 0) 4551 return 0; 4552 4553 mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone)); 4554 /* 4555 * This loop can run a while, specially if mem_cgroup's continuously 4556 * keep exceeding their soft limit and putting the system under 4557 * pressure 4558 */ 4559 do { 4560 if (next_mz) 4561 mz = next_mz; 4562 else 4563 mz = mem_cgroup_largest_soft_limit_node(mctz); 4564 if (!mz) 4565 break; 4566 4567 nr_scanned = 0; 4568 reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone, 4569 gfp_mask, &nr_scanned); 4570 nr_reclaimed += reclaimed; 4571 *total_scanned += nr_scanned; 4572 spin_lock(&mctz->lock); 4573 4574 /* 4575 * If we failed to reclaim anything from this memory cgroup 4576 * it is time to move on to the next cgroup 4577 */ 4578 next_mz = NULL; 4579 if (!reclaimed) { 4580 do { 4581 /* 4582 * Loop until we find yet another one. 4583 * 4584 * By the time we get the soft_limit lock 4585 * again, someone might have aded the 4586 * group back on the RB tree. Iterate to 4587 * make sure we get a different mem. 4588 * mem_cgroup_largest_soft_limit_node returns 4589 * NULL if no other cgroup is present on 4590 * the tree 4591 */ 4592 next_mz = 4593 __mem_cgroup_largest_soft_limit_node(mctz); 4594 if (next_mz == mz) 4595 css_put(&next_mz->memcg->css); 4596 else /* next_mz == NULL or other memcg */ 4597 break; 4598 } while (1); 4599 } 4600 __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz); 4601 excess = res_counter_soft_limit_excess(&mz->memcg->res); 4602 /* 4603 * One school of thought says that we should not add 4604 * back the node to the tree if reclaim returns 0. 4605 * But our reclaim could return 0, simply because due 4606 * to priority we are exposing a smaller subset of 4607 * memory to reclaim from. Consider this as a longer 4608 * term TODO. 4609 */ 4610 /* If excess == 0, no tree ops */ 4611 __mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess); 4612 spin_unlock(&mctz->lock); 4613 css_put(&mz->memcg->css); 4614 loop++; 4615 /* 4616 * Could not reclaim anything and there are no more 4617 * mem cgroups to try or we seem to be looping without 4618 * reclaiming anything. 4619 */ 4620 if (!nr_reclaimed && 4621 (next_mz == NULL || 4622 loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS)) 4623 break; 4624 } while (!nr_reclaimed); 4625 if (next_mz) 4626 css_put(&next_mz->memcg->css); 4627 return nr_reclaimed; 4628 } 4629 4630 /** 4631 * mem_cgroup_force_empty_list - clears LRU of a group 4632 * @memcg: group to clear 4633 * @node: NUMA node 4634 * @zid: zone id 4635 * @lru: lru to to clear 4636 * 4637 * Traverse a specified page_cgroup list and try to drop them all. This doesn't 4638 * reclaim the pages page themselves - pages are moved to the parent (or root) 4639 * group. 4640 */ 4641 static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg, 4642 int node, int zid, enum lru_list lru) 4643 { 4644 struct lruvec *lruvec; 4645 unsigned long flags; 4646 struct list_head *list; 4647 struct page *busy; 4648 struct zone *zone; 4649 4650 zone = &NODE_DATA(node)->node_zones[zid]; 4651 lruvec = mem_cgroup_zone_lruvec(zone, memcg); 4652 list = &lruvec->lists[lru]; 4653 4654 busy = NULL; 4655 do { 4656 struct page_cgroup *pc; 4657 struct page *page; 4658 4659 spin_lock_irqsave(&zone->lru_lock, flags); 4660 if (list_empty(list)) { 4661 spin_unlock_irqrestore(&zone->lru_lock, flags); 4662 break; 4663 } 4664 page = list_entry(list->prev, struct page, lru); 4665 if (busy == page) { 4666 list_move(&page->lru, list); 4667 busy = NULL; 4668 spin_unlock_irqrestore(&zone->lru_lock, flags); 4669 continue; 4670 } 4671 spin_unlock_irqrestore(&zone->lru_lock, flags); 4672 4673 pc = lookup_page_cgroup(page); 4674 4675 if (mem_cgroup_move_parent(page, pc, memcg)) { 4676 /* found lock contention or "pc" is obsolete. */ 4677 busy = page; 4678 } else 4679 busy = NULL; 4680 cond_resched(); 4681 } while (!list_empty(list)); 4682 } 4683 4684 /* 4685 * make mem_cgroup's charge to be 0 if there is no task by moving 4686 * all the charges and pages to the parent. 4687 * This enables deleting this mem_cgroup. 4688 * 4689 * Caller is responsible for holding css reference on the memcg. 4690 */ 4691 static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg) 4692 { 4693 int node, zid; 4694 u64 usage; 4695 4696 do { 4697 /* This is for making all *used* pages to be on LRU. */ 4698 lru_add_drain_all(); 4699 drain_all_stock_sync(memcg); 4700 mem_cgroup_start_move(memcg); 4701 for_each_node_state(node, N_MEMORY) { 4702 for (zid = 0; zid < MAX_NR_ZONES; zid++) { 4703 enum lru_list lru; 4704 for_each_lru(lru) { 4705 mem_cgroup_force_empty_list(memcg, 4706 node, zid, lru); 4707 } 4708 } 4709 } 4710 mem_cgroup_end_move(memcg); 4711 memcg_oom_recover(memcg); 4712 cond_resched(); 4713 4714 /* 4715 * Kernel memory may not necessarily be trackable to a specific 4716 * process. So they are not migrated, and therefore we can't 4717 * expect their value to drop to 0 here. 4718 * Having res filled up with kmem only is enough. 4719 * 4720 * This is a safety check because mem_cgroup_force_empty_list 4721 * could have raced with mem_cgroup_replace_page_cache callers 4722 * so the lru seemed empty but the page could have been added 4723 * right after the check. RES_USAGE should be safe as we always 4724 * charge before adding to the LRU. 4725 */ 4726 usage = res_counter_read_u64(&memcg->res, RES_USAGE) - 4727 res_counter_read_u64(&memcg->kmem, RES_USAGE); 4728 } while (usage > 0); 4729 } 4730 4731 static inline bool memcg_has_children(struct mem_cgroup *memcg) 4732 { 4733 lockdep_assert_held(&memcg_create_mutex); 4734 /* 4735 * The lock does not prevent addition or deletion to the list 4736 * of children, but it prevents a new child from being 4737 * initialized based on this parent in css_online(), so it's 4738 * enough to decide whether hierarchically inherited 4739 * attributes can still be changed or not. 4740 */ 4741 return memcg->use_hierarchy && 4742 !list_empty(&memcg->css.cgroup->children); 4743 } 4744 4745 /* 4746 * Reclaims as many pages from the given memcg as possible and moves 4747 * the rest to the parent. 4748 * 4749 * Caller is responsible for holding css reference for memcg. 4750 */ 4751 static int mem_cgroup_force_empty(struct mem_cgroup *memcg) 4752 { 4753 int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; 4754 struct cgroup *cgrp = memcg->css.cgroup; 4755 4756 /* returns EBUSY if there is a task or if we come here twice. */ 4757 if (cgroup_has_tasks(cgrp) || !list_empty(&cgrp->children)) 4758 return -EBUSY; 4759 4760 /* we call try-to-free pages for make this cgroup empty */ 4761 lru_add_drain_all(); 4762 /* try to free all pages in this cgroup */ 4763 while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) { 4764 int progress; 4765 4766 if (signal_pending(current)) 4767 return -EINTR; 4768 4769 progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL, 4770 false); 4771 if (!progress) { 4772 nr_retries--; 4773 /* maybe some writeback is necessary */ 4774 congestion_wait(BLK_RW_ASYNC, HZ/10); 4775 } 4776 4777 } 4778 lru_add_drain(); 4779 mem_cgroup_reparent_charges(memcg); 4780 4781 return 0; 4782 } 4783 4784 static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css, 4785 unsigned int event) 4786 { 4787 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 4788 4789 if (mem_cgroup_is_root(memcg)) 4790 return -EINVAL; 4791 return mem_cgroup_force_empty(memcg); 4792 } 4793 4794 static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css, 4795 struct cftype *cft) 4796 { 4797 return mem_cgroup_from_css(css)->use_hierarchy; 4798 } 4799 4800 static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css, 4801 struct cftype *cft, u64 val) 4802 { 4803 int retval = 0; 4804 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 4805 struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css)); 4806 4807 mutex_lock(&memcg_create_mutex); 4808 4809 if (memcg->use_hierarchy == val) 4810 goto out; 4811 4812 /* 4813 * If parent's use_hierarchy is set, we can't make any modifications 4814 * in the child subtrees. If it is unset, then the change can 4815 * occur, provided the current cgroup has no children. 4816 * 4817 * For the root cgroup, parent_mem is NULL, we allow value to be 4818 * set if there are no children. 4819 */ 4820 if ((!parent_memcg || !parent_memcg->use_hierarchy) && 4821 (val == 1 || val == 0)) { 4822 if (list_empty(&memcg->css.cgroup->children)) 4823 memcg->use_hierarchy = val; 4824 else 4825 retval = -EBUSY; 4826 } else 4827 retval = -EINVAL; 4828 4829 out: 4830 mutex_unlock(&memcg_create_mutex); 4831 4832 return retval; 4833 } 4834 4835 4836 static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg, 4837 enum mem_cgroup_stat_index idx) 4838 { 4839 struct mem_cgroup *iter; 4840 long val = 0; 4841 4842 /* Per-cpu values can be negative, use a signed accumulator */ 4843 for_each_mem_cgroup_tree(iter, memcg) 4844 val += mem_cgroup_read_stat(iter, idx); 4845 4846 if (val < 0) /* race ? */ 4847 val = 0; 4848 return val; 4849 } 4850 4851 static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) 4852 { 4853 u64 val; 4854 4855 if (!mem_cgroup_is_root(memcg)) { 4856 if (!swap) 4857 return res_counter_read_u64(&memcg->res, RES_USAGE); 4858 else 4859 return res_counter_read_u64(&memcg->memsw, RES_USAGE); 4860 } 4861 4862 /* 4863 * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS 4864 * as well as in MEM_CGROUP_STAT_RSS_HUGE. 4865 */ 4866 val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE); 4867 val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS); 4868 4869 if (swap) 4870 val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP); 4871 4872 return val << PAGE_SHIFT; 4873 } 4874 4875 static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, 4876 struct cftype *cft) 4877 { 4878 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 4879 u64 val; 4880 int name; 4881 enum res_type type; 4882 4883 type = MEMFILE_TYPE(cft->private); 4884 name = MEMFILE_ATTR(cft->private); 4885 4886 switch (type) { 4887 case _MEM: 4888 if (name == RES_USAGE) 4889 val = mem_cgroup_usage(memcg, false); 4890 else 4891 val = res_counter_read_u64(&memcg->res, name); 4892 break; 4893 case _MEMSWAP: 4894 if (name == RES_USAGE) 4895 val = mem_cgroup_usage(memcg, true); 4896 else 4897 val = res_counter_read_u64(&memcg->memsw, name); 4898 break; 4899 case _KMEM: 4900 val = res_counter_read_u64(&memcg->kmem, name); 4901 break; 4902 default: 4903 BUG(); 4904 } 4905 4906 return val; 4907 } 4908 4909 #ifdef CONFIG_MEMCG_KMEM 4910 /* should be called with activate_kmem_mutex held */ 4911 static int __memcg_activate_kmem(struct mem_cgroup *memcg, 4912 unsigned long long limit) 4913 { 4914 int err = 0; 4915 int memcg_id; 4916 4917 if (memcg_kmem_is_active(memcg)) 4918 return 0; 4919 4920 /* 4921 * We are going to allocate memory for data shared by all memory 4922 * cgroups so let's stop accounting here. 4923 */ 4924 memcg_stop_kmem_account(); 4925 4926 /* 4927 * For simplicity, we won't allow this to be disabled. It also can't 4928 * be changed if the cgroup has children already, or if tasks had 4929 * already joined. 4930 * 4931 * If tasks join before we set the limit, a person looking at 4932 * kmem.usage_in_bytes will have no way to determine when it took 4933 * place, which makes the value quite meaningless. 4934 * 4935 * After it first became limited, changes in the value of the limit are 4936 * of course permitted. 4937 */ 4938 mutex_lock(&memcg_create_mutex); 4939 if (cgroup_has_tasks(memcg->css.cgroup) || memcg_has_children(memcg)) 4940 err = -EBUSY; 4941 mutex_unlock(&memcg_create_mutex); 4942 if (err) 4943 goto out; 4944 4945 memcg_id = ida_simple_get(&kmem_limited_groups, 4946 0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL); 4947 if (memcg_id < 0) { 4948 err = memcg_id; 4949 goto out; 4950 } 4951 4952 /* 4953 * Make sure we have enough space for this cgroup in each root cache's 4954 * memcg_params. 4955 */ 4956 mutex_lock(&memcg_slab_mutex); 4957 err = memcg_update_all_caches(memcg_id + 1); 4958 mutex_unlock(&memcg_slab_mutex); 4959 if (err) 4960 goto out_rmid; 4961 4962 memcg->kmemcg_id = memcg_id; 4963 INIT_LIST_HEAD(&memcg->memcg_slab_caches); 4964 4965 /* 4966 * We couldn't have accounted to this cgroup, because it hasn't got the 4967 * active bit set yet, so this should succeed. 4968 */ 4969 err = res_counter_set_limit(&memcg->kmem, limit); 4970 VM_BUG_ON(err); 4971 4972 static_key_slow_inc(&memcg_kmem_enabled_key); 4973 /* 4974 * Setting the active bit after enabling static branching will 4975 * guarantee no one starts accounting before all call sites are 4976 * patched. 4977 */ 4978 memcg_kmem_set_active(memcg); 4979 out: 4980 memcg_resume_kmem_account(); 4981 return err; 4982 4983 out_rmid: 4984 ida_simple_remove(&kmem_limited_groups, memcg_id); 4985 goto out; 4986 } 4987 4988 static int memcg_activate_kmem(struct mem_cgroup *memcg, 4989 unsigned long long limit) 4990 { 4991 int ret; 4992 4993 mutex_lock(&activate_kmem_mutex); 4994 ret = __memcg_activate_kmem(memcg, limit); 4995 mutex_unlock(&activate_kmem_mutex); 4996 return ret; 4997 } 4998 4999 static int memcg_update_kmem_limit(struct mem_cgroup *memcg, 5000 unsigned long long val) 5001 { 5002 int ret; 5003 5004 if (!memcg_kmem_is_active(memcg)) 5005 ret = memcg_activate_kmem(memcg, val); 5006 else 5007 ret = res_counter_set_limit(&memcg->kmem, val); 5008 return ret; 5009 } 5010 5011 static int memcg_propagate_kmem(struct mem_cgroup *memcg) 5012 { 5013 int ret = 0; 5014 struct mem_cgroup *parent = parent_mem_cgroup(memcg); 5015 5016 if (!parent) 5017 return 0; 5018 5019 mutex_lock(&activate_kmem_mutex); 5020 /* 5021 * If the parent cgroup is not kmem-active now, it cannot be activated 5022 * after this point, because it has at least one child already. 5023 */ 5024 if (memcg_kmem_is_active(parent)) 5025 ret = __memcg_activate_kmem(memcg, RES_COUNTER_MAX); 5026 mutex_unlock(&activate_kmem_mutex); 5027 return ret; 5028 } 5029 #else 5030 static int memcg_update_kmem_limit(struct mem_cgroup *memcg, 5031 unsigned long long val) 5032 { 5033 return -EINVAL; 5034 } 5035 #endif /* CONFIG_MEMCG_KMEM */ 5036 5037 /* 5038 * The user of this function is... 5039 * RES_LIMIT. 5040 */ 5041 static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft, 5042 char *buffer) 5043 { 5044 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5045 enum res_type type; 5046 int name; 5047 unsigned long long val; 5048 int ret; 5049 5050 type = MEMFILE_TYPE(cft->private); 5051 name = MEMFILE_ATTR(cft->private); 5052 5053 switch (name) { 5054 case RES_LIMIT: 5055 if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */ 5056 ret = -EINVAL; 5057 break; 5058 } 5059 /* This function does all necessary parse...reuse it */ 5060 ret = res_counter_memparse_write_strategy(buffer, &val); 5061 if (ret) 5062 break; 5063 if (type == _MEM) 5064 ret = mem_cgroup_resize_limit(memcg, val); 5065 else if (type == _MEMSWAP) 5066 ret = mem_cgroup_resize_memsw_limit(memcg, val); 5067 else if (type == _KMEM) 5068 ret = memcg_update_kmem_limit(memcg, val); 5069 else 5070 return -EINVAL; 5071 break; 5072 case RES_SOFT_LIMIT: 5073 ret = res_counter_memparse_write_strategy(buffer, &val); 5074 if (ret) 5075 break; 5076 /* 5077 * For memsw, soft limits are hard to implement in terms 5078 * of semantics, for now, we support soft limits for 5079 * control without swap 5080 */ 5081 if (type == _MEM) 5082 ret = res_counter_set_soft_limit(&memcg->res, val); 5083 else 5084 ret = -EINVAL; 5085 break; 5086 default: 5087 ret = -EINVAL; /* should be BUG() ? */ 5088 break; 5089 } 5090 return ret; 5091 } 5092 5093 static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg, 5094 unsigned long long *mem_limit, unsigned long long *memsw_limit) 5095 { 5096 unsigned long long min_limit, min_memsw_limit, tmp; 5097 5098 min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT); 5099 min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 5100 if (!memcg->use_hierarchy) 5101 goto out; 5102 5103 while (css_parent(&memcg->css)) { 5104 memcg = mem_cgroup_from_css(css_parent(&memcg->css)); 5105 if (!memcg->use_hierarchy) 5106 break; 5107 tmp = res_counter_read_u64(&memcg->res, RES_LIMIT); 5108 min_limit = min(min_limit, tmp); 5109 tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT); 5110 min_memsw_limit = min(min_memsw_limit, tmp); 5111 } 5112 out: 5113 *mem_limit = min_limit; 5114 *memsw_limit = min_memsw_limit; 5115 } 5116 5117 static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event) 5118 { 5119 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5120 int name; 5121 enum res_type type; 5122 5123 type = MEMFILE_TYPE(event); 5124 name = MEMFILE_ATTR(event); 5125 5126 switch (name) { 5127 case RES_MAX_USAGE: 5128 if (type == _MEM) 5129 res_counter_reset_max(&memcg->res); 5130 else if (type == _MEMSWAP) 5131 res_counter_reset_max(&memcg->memsw); 5132 else if (type == _KMEM) 5133 res_counter_reset_max(&memcg->kmem); 5134 else 5135 return -EINVAL; 5136 break; 5137 case RES_FAILCNT: 5138 if (type == _MEM) 5139 res_counter_reset_failcnt(&memcg->res); 5140 else if (type == _MEMSWAP) 5141 res_counter_reset_failcnt(&memcg->memsw); 5142 else if (type == _KMEM) 5143 res_counter_reset_failcnt(&memcg->kmem); 5144 else 5145 return -EINVAL; 5146 break; 5147 } 5148 5149 return 0; 5150 } 5151 5152 static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css, 5153 struct cftype *cft) 5154 { 5155 return mem_cgroup_from_css(css)->move_charge_at_immigrate; 5156 } 5157 5158 #ifdef CONFIG_MMU 5159 static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, 5160 struct cftype *cft, u64 val) 5161 { 5162 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5163 5164 if (val >= (1 << NR_MOVE_TYPE)) 5165 return -EINVAL; 5166 5167 /* 5168 * No kind of locking is needed in here, because ->can_attach() will 5169 * check this value once in the beginning of the process, and then carry 5170 * on with stale data. This means that changes to this value will only 5171 * affect task migrations starting after the change. 5172 */ 5173 memcg->move_charge_at_immigrate = val; 5174 return 0; 5175 } 5176 #else 5177 static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, 5178 struct cftype *cft, u64 val) 5179 { 5180 return -ENOSYS; 5181 } 5182 #endif 5183 5184 #ifdef CONFIG_NUMA 5185 static int memcg_numa_stat_show(struct seq_file *m, void *v) 5186 { 5187 struct numa_stat { 5188 const char *name; 5189 unsigned int lru_mask; 5190 }; 5191 5192 static const struct numa_stat stats[] = { 5193 { "total", LRU_ALL }, 5194 { "file", LRU_ALL_FILE }, 5195 { "anon", LRU_ALL_ANON }, 5196 { "unevictable", BIT(LRU_UNEVICTABLE) }, 5197 }; 5198 const struct numa_stat *stat; 5199 int nid; 5200 unsigned long nr; 5201 struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); 5202 5203 for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { 5204 nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask); 5205 seq_printf(m, "%s=%lu", stat->name, nr); 5206 for_each_node_state(nid, N_MEMORY) { 5207 nr = mem_cgroup_node_nr_lru_pages(memcg, nid, 5208 stat->lru_mask); 5209 seq_printf(m, " N%d=%lu", nid, nr); 5210 } 5211 seq_putc(m, '\n'); 5212 } 5213 5214 for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { 5215 struct mem_cgroup *iter; 5216 5217 nr = 0; 5218 for_each_mem_cgroup_tree(iter, memcg) 5219 nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask); 5220 seq_printf(m, "hierarchical_%s=%lu", stat->name, nr); 5221 for_each_node_state(nid, N_MEMORY) { 5222 nr = 0; 5223 for_each_mem_cgroup_tree(iter, memcg) 5224 nr += mem_cgroup_node_nr_lru_pages( 5225 iter, nid, stat->lru_mask); 5226 seq_printf(m, " N%d=%lu", nid, nr); 5227 } 5228 seq_putc(m, '\n'); 5229 } 5230 5231 return 0; 5232 } 5233 #endif /* CONFIG_NUMA */ 5234 5235 static inline void mem_cgroup_lru_names_not_uptodate(void) 5236 { 5237 BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS); 5238 } 5239 5240 static int memcg_stat_show(struct seq_file *m, void *v) 5241 { 5242 struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); 5243 struct mem_cgroup *mi; 5244 unsigned int i; 5245 5246 for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { 5247 if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account) 5248 continue; 5249 seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i], 5250 mem_cgroup_read_stat(memcg, i) * PAGE_SIZE); 5251 } 5252 5253 for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) 5254 seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i], 5255 mem_cgroup_read_events(memcg, i)); 5256 5257 for (i = 0; i < NR_LRU_LISTS; i++) 5258 seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i], 5259 mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE); 5260 5261 /* Hierarchical information */ 5262 { 5263 unsigned long long limit, memsw_limit; 5264 memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit); 5265 seq_printf(m, "hierarchical_memory_limit %llu\n", limit); 5266 if (do_swap_account) 5267 seq_printf(m, "hierarchical_memsw_limit %llu\n", 5268 memsw_limit); 5269 } 5270 5271 for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { 5272 long long val = 0; 5273 5274 if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account) 5275 continue; 5276 for_each_mem_cgroup_tree(mi, memcg) 5277 val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE; 5278 seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val); 5279 } 5280 5281 for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) { 5282 unsigned long long val = 0; 5283 5284 for_each_mem_cgroup_tree(mi, memcg) 5285 val += mem_cgroup_read_events(mi, i); 5286 seq_printf(m, "total_%s %llu\n", 5287 mem_cgroup_events_names[i], val); 5288 } 5289 5290 for (i = 0; i < NR_LRU_LISTS; i++) { 5291 unsigned long long val = 0; 5292 5293 for_each_mem_cgroup_tree(mi, memcg) 5294 val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE; 5295 seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val); 5296 } 5297 5298 #ifdef CONFIG_DEBUG_VM 5299 { 5300 int nid, zid; 5301 struct mem_cgroup_per_zone *mz; 5302 struct zone_reclaim_stat *rstat; 5303 unsigned long recent_rotated[2] = {0, 0}; 5304 unsigned long recent_scanned[2] = {0, 0}; 5305 5306 for_each_online_node(nid) 5307 for (zid = 0; zid < MAX_NR_ZONES; zid++) { 5308 mz = mem_cgroup_zoneinfo(memcg, nid, zid); 5309 rstat = &mz->lruvec.reclaim_stat; 5310 5311 recent_rotated[0] += rstat->recent_rotated[0]; 5312 recent_rotated[1] += rstat->recent_rotated[1]; 5313 recent_scanned[0] += rstat->recent_scanned[0]; 5314 recent_scanned[1] += rstat->recent_scanned[1]; 5315 } 5316 seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]); 5317 seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]); 5318 seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]); 5319 seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]); 5320 } 5321 #endif 5322 5323 return 0; 5324 } 5325 5326 static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css, 5327 struct cftype *cft) 5328 { 5329 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5330 5331 return mem_cgroup_swappiness(memcg); 5332 } 5333 5334 static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css, 5335 struct cftype *cft, u64 val) 5336 { 5337 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5338 5339 if (val > 100) 5340 return -EINVAL; 5341 5342 if (css_parent(css)) 5343 memcg->swappiness = val; 5344 else 5345 vm_swappiness = val; 5346 5347 return 0; 5348 } 5349 5350 static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) 5351 { 5352 struct mem_cgroup_threshold_ary *t; 5353 u64 usage; 5354 int i; 5355 5356 rcu_read_lock(); 5357 if (!swap) 5358 t = rcu_dereference(memcg->thresholds.primary); 5359 else 5360 t = rcu_dereference(memcg->memsw_thresholds.primary); 5361 5362 if (!t) 5363 goto unlock; 5364 5365 usage = mem_cgroup_usage(memcg, swap); 5366 5367 /* 5368 * current_threshold points to threshold just below or equal to usage. 5369 * If it's not true, a threshold was crossed after last 5370 * call of __mem_cgroup_threshold(). 5371 */ 5372 i = t->current_threshold; 5373 5374 /* 5375 * Iterate backward over array of thresholds starting from 5376 * current_threshold and check if a threshold is crossed. 5377 * If none of thresholds below usage is crossed, we read 5378 * only one element of the array here. 5379 */ 5380 for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--) 5381 eventfd_signal(t->entries[i].eventfd, 1); 5382 5383 /* i = current_threshold + 1 */ 5384 i++; 5385 5386 /* 5387 * Iterate forward over array of thresholds starting from 5388 * current_threshold+1 and check if a threshold is crossed. 5389 * If none of thresholds above usage is crossed, we read 5390 * only one element of the array here. 5391 */ 5392 for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++) 5393 eventfd_signal(t->entries[i].eventfd, 1); 5394 5395 /* Update current_threshold */ 5396 t->current_threshold = i - 1; 5397 unlock: 5398 rcu_read_unlock(); 5399 } 5400 5401 static void mem_cgroup_threshold(struct mem_cgroup *memcg) 5402 { 5403 while (memcg) { 5404 __mem_cgroup_threshold(memcg, false); 5405 if (do_swap_account) 5406 __mem_cgroup_threshold(memcg, true); 5407 5408 memcg = parent_mem_cgroup(memcg); 5409 } 5410 } 5411 5412 static int compare_thresholds(const void *a, const void *b) 5413 { 5414 const struct mem_cgroup_threshold *_a = a; 5415 const struct mem_cgroup_threshold *_b = b; 5416 5417 if (_a->threshold > _b->threshold) 5418 return 1; 5419 5420 if (_a->threshold < _b->threshold) 5421 return -1; 5422 5423 return 0; 5424 } 5425 5426 static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg) 5427 { 5428 struct mem_cgroup_eventfd_list *ev; 5429 5430 list_for_each_entry(ev, &memcg->oom_notify, list) 5431 eventfd_signal(ev->eventfd, 1); 5432 return 0; 5433 } 5434 5435 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg) 5436 { 5437 struct mem_cgroup *iter; 5438 5439 for_each_mem_cgroup_tree(iter, memcg) 5440 mem_cgroup_oom_notify_cb(iter); 5441 } 5442 5443 static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, 5444 struct eventfd_ctx *eventfd, const char *args, enum res_type type) 5445 { 5446 struct mem_cgroup_thresholds *thresholds; 5447 struct mem_cgroup_threshold_ary *new; 5448 u64 threshold, usage; 5449 int i, size, ret; 5450 5451 ret = res_counter_memparse_write_strategy(args, &threshold); 5452 if (ret) 5453 return ret; 5454 5455 mutex_lock(&memcg->thresholds_lock); 5456 5457 if (type == _MEM) 5458 thresholds = &memcg->thresholds; 5459 else if (type == _MEMSWAP) 5460 thresholds = &memcg->memsw_thresholds; 5461 else 5462 BUG(); 5463 5464 usage = mem_cgroup_usage(memcg, type == _MEMSWAP); 5465 5466 /* Check if a threshold crossed before adding a new one */ 5467 if (thresholds->primary) 5468 __mem_cgroup_threshold(memcg, type == _MEMSWAP); 5469 5470 size = thresholds->primary ? thresholds->primary->size + 1 : 1; 5471 5472 /* Allocate memory for new array of thresholds */ 5473 new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold), 5474 GFP_KERNEL); 5475 if (!new) { 5476 ret = -ENOMEM; 5477 goto unlock; 5478 } 5479 new->size = size; 5480 5481 /* Copy thresholds (if any) to new array */ 5482 if (thresholds->primary) { 5483 memcpy(new->entries, thresholds->primary->entries, (size - 1) * 5484 sizeof(struct mem_cgroup_threshold)); 5485 } 5486 5487 /* Add new threshold */ 5488 new->entries[size - 1].eventfd = eventfd; 5489 new->entries[size - 1].threshold = threshold; 5490 5491 /* Sort thresholds. Registering of new threshold isn't time-critical */ 5492 sort(new->entries, size, sizeof(struct mem_cgroup_threshold), 5493 compare_thresholds, NULL); 5494 5495 /* Find current threshold */ 5496 new->current_threshold = -1; 5497 for (i = 0; i < size; i++) { 5498 if (new->entries[i].threshold <= usage) { 5499 /* 5500 * new->current_threshold will not be used until 5501 * rcu_assign_pointer(), so it's safe to increment 5502 * it here. 5503 */ 5504 ++new->current_threshold; 5505 } else 5506 break; 5507 } 5508 5509 /* Free old spare buffer and save old primary buffer as spare */ 5510 kfree(thresholds->spare); 5511 thresholds->spare = thresholds->primary; 5512 5513 rcu_assign_pointer(thresholds->primary, new); 5514 5515 /* To be sure that nobody uses thresholds */ 5516 synchronize_rcu(); 5517 5518 unlock: 5519 mutex_unlock(&memcg->thresholds_lock); 5520 5521 return ret; 5522 } 5523 5524 static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg, 5525 struct eventfd_ctx *eventfd, const char *args) 5526 { 5527 return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM); 5528 } 5529 5530 static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg, 5531 struct eventfd_ctx *eventfd, const char *args) 5532 { 5533 return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP); 5534 } 5535 5536 static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg, 5537 struct eventfd_ctx *eventfd, enum res_type type) 5538 { 5539 struct mem_cgroup_thresholds *thresholds; 5540 struct mem_cgroup_threshold_ary *new; 5541 u64 usage; 5542 int i, j, size; 5543 5544 mutex_lock(&memcg->thresholds_lock); 5545 if (type == _MEM) 5546 thresholds = &memcg->thresholds; 5547 else if (type == _MEMSWAP) 5548 thresholds = &memcg->memsw_thresholds; 5549 else 5550 BUG(); 5551 5552 if (!thresholds->primary) 5553 goto unlock; 5554 5555 usage = mem_cgroup_usage(memcg, type == _MEMSWAP); 5556 5557 /* Check if a threshold crossed before removing */ 5558 __mem_cgroup_threshold(memcg, type == _MEMSWAP); 5559 5560 /* Calculate new number of threshold */ 5561 size = 0; 5562 for (i = 0; i < thresholds->primary->size; i++) { 5563 if (thresholds->primary->entries[i].eventfd != eventfd) 5564 size++; 5565 } 5566 5567 new = thresholds->spare; 5568 5569 /* Set thresholds array to NULL if we don't have thresholds */ 5570 if (!size) { 5571 kfree(new); 5572 new = NULL; 5573 goto swap_buffers; 5574 } 5575 5576 new->size = size; 5577 5578 /* Copy thresholds and find current threshold */ 5579 new->current_threshold = -1; 5580 for (i = 0, j = 0; i < thresholds->primary->size; i++) { 5581 if (thresholds->primary->entries[i].eventfd == eventfd) 5582 continue; 5583 5584 new->entries[j] = thresholds->primary->entries[i]; 5585 if (new->entries[j].threshold <= usage) { 5586 /* 5587 * new->current_threshold will not be used 5588 * until rcu_assign_pointer(), so it's safe to increment 5589 * it here. 5590 */ 5591 ++new->current_threshold; 5592 } 5593 j++; 5594 } 5595 5596 swap_buffers: 5597 /* Swap primary and spare array */ 5598 thresholds->spare = thresholds->primary; 5599 /* If all events are unregistered, free the spare array */ 5600 if (!new) { 5601 kfree(thresholds->spare); 5602 thresholds->spare = NULL; 5603 } 5604 5605 rcu_assign_pointer(thresholds->primary, new); 5606 5607 /* To be sure that nobody uses thresholds */ 5608 synchronize_rcu(); 5609 unlock: 5610 mutex_unlock(&memcg->thresholds_lock); 5611 } 5612 5613 static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg, 5614 struct eventfd_ctx *eventfd) 5615 { 5616 return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM); 5617 } 5618 5619 static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg, 5620 struct eventfd_ctx *eventfd) 5621 { 5622 return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP); 5623 } 5624 5625 static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg, 5626 struct eventfd_ctx *eventfd, const char *args) 5627 { 5628 struct mem_cgroup_eventfd_list *event; 5629 5630 event = kmalloc(sizeof(*event), GFP_KERNEL); 5631 if (!event) 5632 return -ENOMEM; 5633 5634 spin_lock(&memcg_oom_lock); 5635 5636 event->eventfd = eventfd; 5637 list_add(&event->list, &memcg->oom_notify); 5638 5639 /* already in OOM ? */ 5640 if (atomic_read(&memcg->under_oom)) 5641 eventfd_signal(eventfd, 1); 5642 spin_unlock(&memcg_oom_lock); 5643 5644 return 0; 5645 } 5646 5647 static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg, 5648 struct eventfd_ctx *eventfd) 5649 { 5650 struct mem_cgroup_eventfd_list *ev, *tmp; 5651 5652 spin_lock(&memcg_oom_lock); 5653 5654 list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) { 5655 if (ev->eventfd == eventfd) { 5656 list_del(&ev->list); 5657 kfree(ev); 5658 } 5659 } 5660 5661 spin_unlock(&memcg_oom_lock); 5662 } 5663 5664 static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v) 5665 { 5666 struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf)); 5667 5668 seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable); 5669 seq_printf(sf, "under_oom %d\n", (bool)atomic_read(&memcg->under_oom)); 5670 return 0; 5671 } 5672 5673 static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css, 5674 struct cftype *cft, u64 val) 5675 { 5676 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5677 5678 /* cannot set to root cgroup and only 0 and 1 are allowed */ 5679 if (!css_parent(css) || !((val == 0) || (val == 1))) 5680 return -EINVAL; 5681 5682 memcg->oom_kill_disable = val; 5683 if (!val) 5684 memcg_oom_recover(memcg); 5685 5686 return 0; 5687 } 5688 5689 #ifdef CONFIG_MEMCG_KMEM 5690 static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) 5691 { 5692 int ret; 5693 5694 memcg->kmemcg_id = -1; 5695 ret = memcg_propagate_kmem(memcg); 5696 if (ret) 5697 return ret; 5698 5699 return mem_cgroup_sockets_init(memcg, ss); 5700 } 5701 5702 static void memcg_destroy_kmem(struct mem_cgroup *memcg) 5703 { 5704 mem_cgroup_sockets_destroy(memcg); 5705 } 5706 5707 static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) 5708 { 5709 if (!memcg_kmem_is_active(memcg)) 5710 return; 5711 5712 /* 5713 * kmem charges can outlive the cgroup. In the case of slab 5714 * pages, for instance, a page contain objects from various 5715 * processes. As we prevent from taking a reference for every 5716 * such allocation we have to be careful when doing uncharge 5717 * (see memcg_uncharge_kmem) and here during offlining. 5718 * 5719 * The idea is that that only the _last_ uncharge which sees 5720 * the dead memcg will drop the last reference. An additional 5721 * reference is taken here before the group is marked dead 5722 * which is then paired with css_put during uncharge resp. here. 5723 * 5724 * Although this might sound strange as this path is called from 5725 * css_offline() when the referencemight have dropped down to 0 5726 * and shouldn't be incremented anymore (css_tryget would fail) 5727 * we do not have other options because of the kmem allocations 5728 * lifetime. 5729 */ 5730 css_get(&memcg->css); 5731 5732 memcg_kmem_mark_dead(memcg); 5733 5734 if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0) 5735 return; 5736 5737 if (memcg_kmem_test_and_clear_dead(memcg)) 5738 css_put(&memcg->css); 5739 } 5740 #else 5741 static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) 5742 { 5743 return 0; 5744 } 5745 5746 static void memcg_destroy_kmem(struct mem_cgroup *memcg) 5747 { 5748 } 5749 5750 static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) 5751 { 5752 } 5753 #endif 5754 5755 /* 5756 * DO NOT USE IN NEW FILES. 5757 * 5758 * "cgroup.event_control" implementation. 5759 * 5760 * This is way over-engineered. It tries to support fully configurable 5761 * events for each user. Such level of flexibility is completely 5762 * unnecessary especially in the light of the planned unified hierarchy. 5763 * 5764 * Please deprecate this and replace with something simpler if at all 5765 * possible. 5766 */ 5767 5768 /* 5769 * Unregister event and free resources. 5770 * 5771 * Gets called from workqueue. 5772 */ 5773 static void memcg_event_remove(struct work_struct *work) 5774 { 5775 struct mem_cgroup_event *event = 5776 container_of(work, struct mem_cgroup_event, remove); 5777 struct mem_cgroup *memcg = event->memcg; 5778 5779 remove_wait_queue(event->wqh, &event->wait); 5780 5781 event->unregister_event(memcg, event->eventfd); 5782 5783 /* Notify userspace the event is going away. */ 5784 eventfd_signal(event->eventfd, 1); 5785 5786 eventfd_ctx_put(event->eventfd); 5787 kfree(event); 5788 css_put(&memcg->css); 5789 } 5790 5791 /* 5792 * Gets called on POLLHUP on eventfd when user closes it. 5793 * 5794 * Called with wqh->lock held and interrupts disabled. 5795 */ 5796 static int memcg_event_wake(wait_queue_t *wait, unsigned mode, 5797 int sync, void *key) 5798 { 5799 struct mem_cgroup_event *event = 5800 container_of(wait, struct mem_cgroup_event, wait); 5801 struct mem_cgroup *memcg = event->memcg; 5802 unsigned long flags = (unsigned long)key; 5803 5804 if (flags & POLLHUP) { 5805 /* 5806 * If the event has been detached at cgroup removal, we 5807 * can simply return knowing the other side will cleanup 5808 * for us. 5809 * 5810 * We can't race against event freeing since the other 5811 * side will require wqh->lock via remove_wait_queue(), 5812 * which we hold. 5813 */ 5814 spin_lock(&memcg->event_list_lock); 5815 if (!list_empty(&event->list)) { 5816 list_del_init(&event->list); 5817 /* 5818 * We are in atomic context, but cgroup_event_remove() 5819 * may sleep, so we have to call it in workqueue. 5820 */ 5821 schedule_work(&event->remove); 5822 } 5823 spin_unlock(&memcg->event_list_lock); 5824 } 5825 5826 return 0; 5827 } 5828 5829 static void memcg_event_ptable_queue_proc(struct file *file, 5830 wait_queue_head_t *wqh, poll_table *pt) 5831 { 5832 struct mem_cgroup_event *event = 5833 container_of(pt, struct mem_cgroup_event, pt); 5834 5835 event->wqh = wqh; 5836 add_wait_queue(wqh, &event->wait); 5837 } 5838 5839 /* 5840 * DO NOT USE IN NEW FILES. 5841 * 5842 * Parse input and register new cgroup event handler. 5843 * 5844 * Input must be in format '<event_fd> <control_fd> <args>'. 5845 * Interpretation of args is defined by control file implementation. 5846 */ 5847 static int memcg_write_event_control(struct cgroup_subsys_state *css, 5848 struct cftype *cft, char *buffer) 5849 { 5850 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 5851 struct mem_cgroup_event *event; 5852 struct cgroup_subsys_state *cfile_css; 5853 unsigned int efd, cfd; 5854 struct fd efile; 5855 struct fd cfile; 5856 const char *name; 5857 char *endp; 5858 int ret; 5859 5860 efd = simple_strtoul(buffer, &endp, 10); 5861 if (*endp != ' ') 5862 return -EINVAL; 5863 buffer = endp + 1; 5864 5865 cfd = simple_strtoul(buffer, &endp, 10); 5866 if ((*endp != ' ') && (*endp != '\0')) 5867 return -EINVAL; 5868 buffer = endp + 1; 5869 5870 event = kzalloc(sizeof(*event), GFP_KERNEL); 5871 if (!event) 5872 return -ENOMEM; 5873 5874 event->memcg = memcg; 5875 INIT_LIST_HEAD(&event->list); 5876 init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc); 5877 init_waitqueue_func_entry(&event->wait, memcg_event_wake); 5878 INIT_WORK(&event->remove, memcg_event_remove); 5879 5880 efile = fdget(efd); 5881 if (!efile.file) { 5882 ret = -EBADF; 5883 goto out_kfree; 5884 } 5885 5886 event->eventfd = eventfd_ctx_fileget(efile.file); 5887 if (IS_ERR(event->eventfd)) { 5888 ret = PTR_ERR(event->eventfd); 5889 goto out_put_efile; 5890 } 5891 5892 cfile = fdget(cfd); 5893 if (!cfile.file) { 5894 ret = -EBADF; 5895 goto out_put_eventfd; 5896 } 5897 5898 /* the process need read permission on control file */ 5899 /* AV: shouldn't we check that it's been opened for read instead? */ 5900 ret = inode_permission(file_inode(cfile.file), MAY_READ); 5901 if (ret < 0) 5902 goto out_put_cfile; 5903 5904 /* 5905 * Determine the event callbacks and set them in @event. This used 5906 * to be done via struct cftype but cgroup core no longer knows 5907 * about these events. The following is crude but the whole thing 5908 * is for compatibility anyway. 5909 * 5910 * DO NOT ADD NEW FILES. 5911 */ 5912 name = cfile.file->f_dentry->d_name.name; 5913 5914 if (!strcmp(name, "memory.usage_in_bytes")) { 5915 event->register_event = mem_cgroup_usage_register_event; 5916 event->unregister_event = mem_cgroup_usage_unregister_event; 5917 } else if (!strcmp(name, "memory.oom_control")) { 5918 event->register_event = mem_cgroup_oom_register_event; 5919 event->unregister_event = mem_cgroup_oom_unregister_event; 5920 } else if (!strcmp(name, "memory.pressure_level")) { 5921 event->register_event = vmpressure_register_event; 5922 event->unregister_event = vmpressure_unregister_event; 5923 } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) { 5924 event->register_event = memsw_cgroup_usage_register_event; 5925 event->unregister_event = memsw_cgroup_usage_unregister_event; 5926 } else { 5927 ret = -EINVAL; 5928 goto out_put_cfile; 5929 } 5930 5931 /* 5932 * Verify @cfile should belong to @css. Also, remaining events are 5933 * automatically removed on cgroup destruction but the removal is 5934 * asynchronous, so take an extra ref on @css. 5935 */ 5936 cfile_css = css_tryget_from_dir(cfile.file->f_dentry->d_parent, 5937 &memory_cgrp_subsys); 5938 ret = -EINVAL; 5939 if (IS_ERR(cfile_css)) 5940 goto out_put_cfile; 5941 if (cfile_css != css) { 5942 css_put(cfile_css); 5943 goto out_put_cfile; 5944 } 5945 5946 ret = event->register_event(memcg, event->eventfd, buffer); 5947 if (ret) 5948 goto out_put_css; 5949 5950 efile.file->f_op->poll(efile.file, &event->pt); 5951 5952 spin_lock(&memcg->event_list_lock); 5953 list_add(&event->list, &memcg->event_list); 5954 spin_unlock(&memcg->event_list_lock); 5955 5956 fdput(cfile); 5957 fdput(efile); 5958 5959 return 0; 5960 5961 out_put_css: 5962 css_put(css); 5963 out_put_cfile: 5964 fdput(cfile); 5965 out_put_eventfd: 5966 eventfd_ctx_put(event->eventfd); 5967 out_put_efile: 5968 fdput(efile); 5969 out_kfree: 5970 kfree(event); 5971 5972 return ret; 5973 } 5974 5975 static struct cftype mem_cgroup_files[] = { 5976 { 5977 .name = "usage_in_bytes", 5978 .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), 5979 .read_u64 = mem_cgroup_read_u64, 5980 }, 5981 { 5982 .name = "max_usage_in_bytes", 5983 .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE), 5984 .trigger = mem_cgroup_reset, 5985 .read_u64 = mem_cgroup_read_u64, 5986 }, 5987 { 5988 .name = "limit_in_bytes", 5989 .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT), 5990 .write_string = mem_cgroup_write, 5991 .read_u64 = mem_cgroup_read_u64, 5992 }, 5993 { 5994 .name = "soft_limit_in_bytes", 5995 .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT), 5996 .write_string = mem_cgroup_write, 5997 .read_u64 = mem_cgroup_read_u64, 5998 }, 5999 { 6000 .name = "failcnt", 6001 .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT), 6002 .trigger = mem_cgroup_reset, 6003 .read_u64 = mem_cgroup_read_u64, 6004 }, 6005 { 6006 .name = "stat", 6007 .seq_show = memcg_stat_show, 6008 }, 6009 { 6010 .name = "force_empty", 6011 .trigger = mem_cgroup_force_empty_write, 6012 }, 6013 { 6014 .name = "use_hierarchy", 6015 .flags = CFTYPE_INSANE, 6016 .write_u64 = mem_cgroup_hierarchy_write, 6017 .read_u64 = mem_cgroup_hierarchy_read, 6018 }, 6019 { 6020 .name = "cgroup.event_control", /* XXX: for compat */ 6021 .write_string = memcg_write_event_control, 6022 .flags = CFTYPE_NO_PREFIX, 6023 .mode = S_IWUGO, 6024 }, 6025 { 6026 .name = "swappiness", 6027 .read_u64 = mem_cgroup_swappiness_read, 6028 .write_u64 = mem_cgroup_swappiness_write, 6029 }, 6030 { 6031 .name = "move_charge_at_immigrate", 6032 .read_u64 = mem_cgroup_move_charge_read, 6033 .write_u64 = mem_cgroup_move_charge_write, 6034 }, 6035 { 6036 .name = "oom_control", 6037 .seq_show = mem_cgroup_oom_control_read, 6038 .write_u64 = mem_cgroup_oom_control_write, 6039 .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL), 6040 }, 6041 { 6042 .name = "pressure_level", 6043 }, 6044 #ifdef CONFIG_NUMA 6045 { 6046 .name = "numa_stat", 6047 .seq_show = memcg_numa_stat_show, 6048 }, 6049 #endif 6050 #ifdef CONFIG_MEMCG_KMEM 6051 { 6052 .name = "kmem.limit_in_bytes", 6053 .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT), 6054 .write_string = mem_cgroup_write, 6055 .read_u64 = mem_cgroup_read_u64, 6056 }, 6057 { 6058 .name = "kmem.usage_in_bytes", 6059 .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), 6060 .read_u64 = mem_cgroup_read_u64, 6061 }, 6062 { 6063 .name = "kmem.failcnt", 6064 .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), 6065 .trigger = mem_cgroup_reset, 6066 .read_u64 = mem_cgroup_read_u64, 6067 }, 6068 { 6069 .name = "kmem.max_usage_in_bytes", 6070 .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), 6071 .trigger = mem_cgroup_reset, 6072 .read_u64 = mem_cgroup_read_u64, 6073 }, 6074 #ifdef CONFIG_SLABINFO 6075 { 6076 .name = "kmem.slabinfo", 6077 .seq_show = mem_cgroup_slabinfo_read, 6078 }, 6079 #endif 6080 #endif 6081 { }, /* terminate */ 6082 }; 6083 6084 #ifdef CONFIG_MEMCG_SWAP 6085 static struct cftype memsw_cgroup_files[] = { 6086 { 6087 .name = "memsw.usage_in_bytes", 6088 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), 6089 .read_u64 = mem_cgroup_read_u64, 6090 }, 6091 { 6092 .name = "memsw.max_usage_in_bytes", 6093 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), 6094 .trigger = mem_cgroup_reset, 6095 .read_u64 = mem_cgroup_read_u64, 6096 }, 6097 { 6098 .name = "memsw.limit_in_bytes", 6099 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), 6100 .write_string = mem_cgroup_write, 6101 .read_u64 = mem_cgroup_read_u64, 6102 }, 6103 { 6104 .name = "memsw.failcnt", 6105 .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), 6106 .trigger = mem_cgroup_reset, 6107 .read_u64 = mem_cgroup_read_u64, 6108 }, 6109 { }, /* terminate */ 6110 }; 6111 #endif 6112 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node) 6113 { 6114 struct mem_cgroup_per_node *pn; 6115 struct mem_cgroup_per_zone *mz; 6116 int zone, tmp = node; 6117 /* 6118 * This routine is called against possible nodes. 6119 * But it's BUG to call kmalloc() against offline node. 6120 * 6121 * TODO: this routine can waste much memory for nodes which will 6122 * never be onlined. It's better to use memory hotplug callback 6123 * function. 6124 */ 6125 if (!node_state(node, N_NORMAL_MEMORY)) 6126 tmp = -1; 6127 pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp); 6128 if (!pn) 6129 return 1; 6130 6131 for (zone = 0; zone < MAX_NR_ZONES; zone++) { 6132 mz = &pn->zoneinfo[zone]; 6133 lruvec_init(&mz->lruvec); 6134 mz->usage_in_excess = 0; 6135 mz->on_tree = false; 6136 mz->memcg = memcg; 6137 } 6138 memcg->nodeinfo[node] = pn; 6139 return 0; 6140 } 6141 6142 static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node) 6143 { 6144 kfree(memcg->nodeinfo[node]); 6145 } 6146 6147 static struct mem_cgroup *mem_cgroup_alloc(void) 6148 { 6149 struct mem_cgroup *memcg; 6150 size_t size; 6151 6152 size = sizeof(struct mem_cgroup); 6153 size += nr_node_ids * sizeof(struct mem_cgroup_per_node *); 6154 6155 memcg = kzalloc(size, GFP_KERNEL); 6156 if (!memcg) 6157 return NULL; 6158 6159 memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu); 6160 if (!memcg->stat) 6161 goto out_free; 6162 spin_lock_init(&memcg->pcp_counter_lock); 6163 return memcg; 6164 6165 out_free: 6166 kfree(memcg); 6167 return NULL; 6168 } 6169 6170 /* 6171 * At destroying mem_cgroup, references from swap_cgroup can remain. 6172 * (scanning all at force_empty is too costly...) 6173 * 6174 * Instead of clearing all references at force_empty, we remember 6175 * the number of reference from swap_cgroup and free mem_cgroup when 6176 * it goes down to 0. 6177 * 6178 * Removal of cgroup itself succeeds regardless of refs from swap. 6179 */ 6180 6181 static void __mem_cgroup_free(struct mem_cgroup *memcg) 6182 { 6183 int node; 6184 6185 mem_cgroup_remove_from_trees(memcg); 6186 6187 for_each_node(node) 6188 free_mem_cgroup_per_zone_info(memcg, node); 6189 6190 free_percpu(memcg->stat); 6191 6192 /* 6193 * We need to make sure that (at least for now), the jump label 6194 * destruction code runs outside of the cgroup lock. This is because 6195 * get_online_cpus(), which is called from the static_branch update, 6196 * can't be called inside the cgroup_lock. cpusets are the ones 6197 * enforcing this dependency, so if they ever change, we might as well. 6198 * 6199 * schedule_work() will guarantee this happens. Be careful if you need 6200 * to move this code around, and make sure it is outside 6201 * the cgroup_lock. 6202 */ 6203 disarm_static_keys(memcg); 6204 kfree(memcg); 6205 } 6206 6207 /* 6208 * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled. 6209 */ 6210 struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg) 6211 { 6212 if (!memcg->res.parent) 6213 return NULL; 6214 return mem_cgroup_from_res_counter(memcg->res.parent, res); 6215 } 6216 EXPORT_SYMBOL(parent_mem_cgroup); 6217 6218 static void __init mem_cgroup_soft_limit_tree_init(void) 6219 { 6220 struct mem_cgroup_tree_per_node *rtpn; 6221 struct mem_cgroup_tree_per_zone *rtpz; 6222 int tmp, node, zone; 6223 6224 for_each_node(node) { 6225 tmp = node; 6226 if (!node_state(node, N_NORMAL_MEMORY)) 6227 tmp = -1; 6228 rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp); 6229 BUG_ON(!rtpn); 6230 6231 soft_limit_tree.rb_tree_per_node[node] = rtpn; 6232 6233 for (zone = 0; zone < MAX_NR_ZONES; zone++) { 6234 rtpz = &rtpn->rb_tree_per_zone[zone]; 6235 rtpz->rb_root = RB_ROOT; 6236 spin_lock_init(&rtpz->lock); 6237 } 6238 } 6239 } 6240 6241 static struct cgroup_subsys_state * __ref 6242 mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 6243 { 6244 struct mem_cgroup *memcg; 6245 long error = -ENOMEM; 6246 int node; 6247 6248 memcg = mem_cgroup_alloc(); 6249 if (!memcg) 6250 return ERR_PTR(error); 6251 6252 for_each_node(node) 6253 if (alloc_mem_cgroup_per_zone_info(memcg, node)) 6254 goto free_out; 6255 6256 /* root ? */ 6257 if (parent_css == NULL) { 6258 root_mem_cgroup = memcg; 6259 res_counter_init(&memcg->res, NULL); 6260 res_counter_init(&memcg->memsw, NULL); 6261 res_counter_init(&memcg->kmem, NULL); 6262 } 6263 6264 memcg->last_scanned_node = MAX_NUMNODES; 6265 INIT_LIST_HEAD(&memcg->oom_notify); 6266 memcg->move_charge_at_immigrate = 0; 6267 mutex_init(&memcg->thresholds_lock); 6268 spin_lock_init(&memcg->move_lock); 6269 vmpressure_init(&memcg->vmpressure); 6270 INIT_LIST_HEAD(&memcg->event_list); 6271 spin_lock_init(&memcg->event_list_lock); 6272 6273 return &memcg->css; 6274 6275 free_out: 6276 __mem_cgroup_free(memcg); 6277 return ERR_PTR(error); 6278 } 6279 6280 static int 6281 mem_cgroup_css_online(struct cgroup_subsys_state *css) 6282 { 6283 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 6284 struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css)); 6285 6286 if (css->cgroup->id > MEM_CGROUP_ID_MAX) 6287 return -ENOSPC; 6288 6289 if (!parent) 6290 return 0; 6291 6292 mutex_lock(&memcg_create_mutex); 6293 6294 memcg->use_hierarchy = parent->use_hierarchy; 6295 memcg->oom_kill_disable = parent->oom_kill_disable; 6296 memcg->swappiness = mem_cgroup_swappiness(parent); 6297 6298 if (parent->use_hierarchy) { 6299 res_counter_init(&memcg->res, &parent->res); 6300 res_counter_init(&memcg->memsw, &parent->memsw); 6301 res_counter_init(&memcg->kmem, &parent->kmem); 6302 6303 /* 6304 * No need to take a reference to the parent because cgroup 6305 * core guarantees its existence. 6306 */ 6307 } else { 6308 res_counter_init(&memcg->res, NULL); 6309 res_counter_init(&memcg->memsw, NULL); 6310 res_counter_init(&memcg->kmem, NULL); 6311 /* 6312 * Deeper hierachy with use_hierarchy == false doesn't make 6313 * much sense so let cgroup subsystem know about this 6314 * unfortunate state in our controller. 6315 */ 6316 if (parent != root_mem_cgroup) 6317 memory_cgrp_subsys.broken_hierarchy = true; 6318 } 6319 mutex_unlock(&memcg_create_mutex); 6320 6321 return memcg_init_kmem(memcg, &memory_cgrp_subsys); 6322 } 6323 6324 /* 6325 * Announce all parents that a group from their hierarchy is gone. 6326 */ 6327 static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg) 6328 { 6329 struct mem_cgroup *parent = memcg; 6330 6331 while ((parent = parent_mem_cgroup(parent))) 6332 mem_cgroup_iter_invalidate(parent); 6333 6334 /* 6335 * if the root memcg is not hierarchical we have to check it 6336 * explicitely. 6337 */ 6338 if (!root_mem_cgroup->use_hierarchy) 6339 mem_cgroup_iter_invalidate(root_mem_cgroup); 6340 } 6341 6342 static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) 6343 { 6344 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 6345 struct mem_cgroup_event *event, *tmp; 6346 struct cgroup_subsys_state *iter; 6347 6348 /* 6349 * Unregister events and notify userspace. 6350 * Notify userspace about cgroup removing only after rmdir of cgroup 6351 * directory to avoid race between userspace and kernelspace. 6352 */ 6353 spin_lock(&memcg->event_list_lock); 6354 list_for_each_entry_safe(event, tmp, &memcg->event_list, list) { 6355 list_del_init(&event->list); 6356 schedule_work(&event->remove); 6357 } 6358 spin_unlock(&memcg->event_list_lock); 6359 6360 kmem_cgroup_css_offline(memcg); 6361 6362 mem_cgroup_invalidate_reclaim_iterators(memcg); 6363 6364 /* 6365 * This requires that offlining is serialized. Right now that is 6366 * guaranteed because css_killed_work_fn() holds the cgroup_mutex. 6367 */ 6368 css_for_each_descendant_post(iter, css) 6369 mem_cgroup_reparent_charges(mem_cgroup_from_css(iter)); 6370 6371 memcg_unregister_all_caches(memcg); 6372 vmpressure_cleanup(&memcg->vmpressure); 6373 } 6374 6375 static void mem_cgroup_css_free(struct cgroup_subsys_state *css) 6376 { 6377 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 6378 /* 6379 * XXX: css_offline() would be where we should reparent all 6380 * memory to prepare the cgroup for destruction. However, 6381 * memcg does not do css_tryget() and res_counter charging 6382 * under the same RCU lock region, which means that charging 6383 * could race with offlining. Offlining only happens to 6384 * cgroups with no tasks in them but charges can show up 6385 * without any tasks from the swapin path when the target 6386 * memcg is looked up from the swapout record and not from the 6387 * current task as it usually is. A race like this can leak 6388 * charges and put pages with stale cgroup pointers into 6389 * circulation: 6390 * 6391 * #0 #1 6392 * lookup_swap_cgroup_id() 6393 * rcu_read_lock() 6394 * mem_cgroup_lookup() 6395 * css_tryget() 6396 * rcu_read_unlock() 6397 * disable css_tryget() 6398 * call_rcu() 6399 * offline_css() 6400 * reparent_charges() 6401 * res_counter_charge() 6402 * css_put() 6403 * css_free() 6404 * pc->mem_cgroup = dead memcg 6405 * add page to lru 6406 * 6407 * The bulk of the charges are still moved in offline_css() to 6408 * avoid pinning a lot of pages in case a long-term reference 6409 * like a swapout record is deferring the css_free() to long 6410 * after offlining. But this makes sure we catch any charges 6411 * made after offlining: 6412 */ 6413 mem_cgroup_reparent_charges(memcg); 6414 6415 memcg_destroy_kmem(memcg); 6416 __mem_cgroup_free(memcg); 6417 } 6418 6419 #ifdef CONFIG_MMU 6420 /* Handlers for move charge at task migration. */ 6421 #define PRECHARGE_COUNT_AT_ONCE 256 6422 static int mem_cgroup_do_precharge(unsigned long count) 6423 { 6424 int ret = 0; 6425 int batch_count = PRECHARGE_COUNT_AT_ONCE; 6426 struct mem_cgroup *memcg = mc.to; 6427 6428 if (mem_cgroup_is_root(memcg)) { 6429 mc.precharge += count; 6430 /* we don't need css_get for root */ 6431 return ret; 6432 } 6433 /* try to charge at once */ 6434 if (count > 1) { 6435 struct res_counter *dummy; 6436 /* 6437 * "memcg" cannot be under rmdir() because we've already checked 6438 * by cgroup_lock_live_cgroup() that it is not removed and we 6439 * are still under the same cgroup_mutex. So we can postpone 6440 * css_get(). 6441 */ 6442 if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy)) 6443 goto one_by_one; 6444 if (do_swap_account && res_counter_charge(&memcg->memsw, 6445 PAGE_SIZE * count, &dummy)) { 6446 res_counter_uncharge(&memcg->res, PAGE_SIZE * count); 6447 goto one_by_one; 6448 } 6449 mc.precharge += count; 6450 return ret; 6451 } 6452 one_by_one: 6453 /* fall back to one by one charge */ 6454 while (count--) { 6455 if (signal_pending(current)) { 6456 ret = -EINTR; 6457 break; 6458 } 6459 if (!batch_count--) { 6460 batch_count = PRECHARGE_COUNT_AT_ONCE; 6461 cond_resched(); 6462 } 6463 ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false); 6464 if (ret) 6465 /* mem_cgroup_clear_mc() will do uncharge later */ 6466 return ret; 6467 mc.precharge++; 6468 } 6469 return ret; 6470 } 6471 6472 /** 6473 * get_mctgt_type - get target type of moving charge 6474 * @vma: the vma the pte to be checked belongs 6475 * @addr: the address corresponding to the pte to be checked 6476 * @ptent: the pte to be checked 6477 * @target: the pointer the target page or swap ent will be stored(can be NULL) 6478 * 6479 * Returns 6480 * 0(MC_TARGET_NONE): if the pte is not a target for move charge. 6481 * 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for 6482 * move charge. if @target is not NULL, the page is stored in target->page 6483 * with extra refcnt got(Callers should handle it). 6484 * 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a 6485 * target for charge migration. if @target is not NULL, the entry is stored 6486 * in target->ent. 6487 * 6488 * Called with pte lock held. 6489 */ 6490 union mc_target { 6491 struct page *page; 6492 swp_entry_t ent; 6493 }; 6494 6495 enum mc_target_type { 6496 MC_TARGET_NONE = 0, 6497 MC_TARGET_PAGE, 6498 MC_TARGET_SWAP, 6499 }; 6500 6501 static struct page *mc_handle_present_pte(struct vm_area_struct *vma, 6502 unsigned long addr, pte_t ptent) 6503 { 6504 struct page *page = vm_normal_page(vma, addr, ptent); 6505 6506 if (!page || !page_mapped(page)) 6507 return NULL; 6508 if (PageAnon(page)) { 6509 /* we don't move shared anon */ 6510 if (!move_anon()) 6511 return NULL; 6512 } else if (!move_file()) 6513 /* we ignore mapcount for file pages */ 6514 return NULL; 6515 if (!get_page_unless_zero(page)) 6516 return NULL; 6517 6518 return page; 6519 } 6520 6521 #ifdef CONFIG_SWAP 6522 static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, 6523 unsigned long addr, pte_t ptent, swp_entry_t *entry) 6524 { 6525 struct page *page = NULL; 6526 swp_entry_t ent = pte_to_swp_entry(ptent); 6527 6528 if (!move_anon() || non_swap_entry(ent)) 6529 return NULL; 6530 /* 6531 * Because lookup_swap_cache() updates some statistics counter, 6532 * we call find_get_page() with swapper_space directly. 6533 */ 6534 page = find_get_page(swap_address_space(ent), ent.val); 6535 if (do_swap_account) 6536 entry->val = ent.val; 6537 6538 return page; 6539 } 6540 #else 6541 static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, 6542 unsigned long addr, pte_t ptent, swp_entry_t *entry) 6543 { 6544 return NULL; 6545 } 6546 #endif 6547 6548 static struct page *mc_handle_file_pte(struct vm_area_struct *vma, 6549 unsigned long addr, pte_t ptent, swp_entry_t *entry) 6550 { 6551 struct page *page = NULL; 6552 struct address_space *mapping; 6553 pgoff_t pgoff; 6554 6555 if (!vma->vm_file) /* anonymous vma */ 6556 return NULL; 6557 if (!move_file()) 6558 return NULL; 6559 6560 mapping = vma->vm_file->f_mapping; 6561 if (pte_none(ptent)) 6562 pgoff = linear_page_index(vma, addr); 6563 else /* pte_file(ptent) is true */ 6564 pgoff = pte_to_pgoff(ptent); 6565 6566 /* page is moved even if it's not RSS of this task(page-faulted). */ 6567 #ifdef CONFIG_SWAP 6568 /* shmem/tmpfs may report page out on swap: account for that too. */ 6569 if (shmem_mapping(mapping)) { 6570 page = find_get_entry(mapping, pgoff); 6571 if (radix_tree_exceptional_entry(page)) { 6572 swp_entry_t swp = radix_to_swp_entry(page); 6573 if (do_swap_account) 6574 *entry = swp; 6575 page = find_get_page(swap_address_space(swp), swp.val); 6576 } 6577 } else 6578 page = find_get_page(mapping, pgoff); 6579 #else 6580 page = find_get_page(mapping, pgoff); 6581 #endif 6582 return page; 6583 } 6584 6585 static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma, 6586 unsigned long addr, pte_t ptent, union mc_target *target) 6587 { 6588 struct page *page = NULL; 6589 struct page_cgroup *pc; 6590 enum mc_target_type ret = MC_TARGET_NONE; 6591 swp_entry_t ent = { .val = 0 }; 6592 6593 if (pte_present(ptent)) 6594 page = mc_handle_present_pte(vma, addr, ptent); 6595 else if (is_swap_pte(ptent)) 6596 page = mc_handle_swap_pte(vma, addr, ptent, &ent); 6597 else if (pte_none(ptent) || pte_file(ptent)) 6598 page = mc_handle_file_pte(vma, addr, ptent, &ent); 6599 6600 if (!page && !ent.val) 6601 return ret; 6602 if (page) { 6603 pc = lookup_page_cgroup(page); 6604 /* 6605 * Do only loose check w/o page_cgroup lock. 6606 * mem_cgroup_move_account() checks the pc is valid or not under 6607 * the lock. 6608 */ 6609 if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) { 6610 ret = MC_TARGET_PAGE; 6611 if (target) 6612 target->page = page; 6613 } 6614 if (!ret || !target) 6615 put_page(page); 6616 } 6617 /* There is a swap entry and a page doesn't exist or isn't charged */ 6618 if (ent.val && !ret && 6619 mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) { 6620 ret = MC_TARGET_SWAP; 6621 if (target) 6622 target->ent = ent; 6623 } 6624 return ret; 6625 } 6626 6627 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 6628 /* 6629 * We don't consider swapping or file mapped pages because THP does not 6630 * support them for now. 6631 * Caller should make sure that pmd_trans_huge(pmd) is true. 6632 */ 6633 static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, 6634 unsigned long addr, pmd_t pmd, union mc_target *target) 6635 { 6636 struct page *page = NULL; 6637 struct page_cgroup *pc; 6638 enum mc_target_type ret = MC_TARGET_NONE; 6639 6640 page = pmd_page(pmd); 6641 VM_BUG_ON_PAGE(!page || !PageHead(page), page); 6642 if (!move_anon()) 6643 return ret; 6644 pc = lookup_page_cgroup(page); 6645 if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) { 6646 ret = MC_TARGET_PAGE; 6647 if (target) { 6648 get_page(page); 6649 target->page = page; 6650 } 6651 } 6652 return ret; 6653 } 6654 #else 6655 static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, 6656 unsigned long addr, pmd_t pmd, union mc_target *target) 6657 { 6658 return MC_TARGET_NONE; 6659 } 6660 #endif 6661 6662 static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, 6663 unsigned long addr, unsigned long end, 6664 struct mm_walk *walk) 6665 { 6666 struct vm_area_struct *vma = walk->private; 6667 pte_t *pte; 6668 spinlock_t *ptl; 6669 6670 if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { 6671 if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) 6672 mc.precharge += HPAGE_PMD_NR; 6673 spin_unlock(ptl); 6674 return 0; 6675 } 6676 6677 if (pmd_trans_unstable(pmd)) 6678 return 0; 6679 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 6680 for (; addr != end; pte++, addr += PAGE_SIZE) 6681 if (get_mctgt_type(vma, addr, *pte, NULL)) 6682 mc.precharge++; /* increment precharge temporarily */ 6683 pte_unmap_unlock(pte - 1, ptl); 6684 cond_resched(); 6685 6686 return 0; 6687 } 6688 6689 static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) 6690 { 6691 unsigned long precharge; 6692 struct vm_area_struct *vma; 6693 6694 down_read(&mm->mmap_sem); 6695 for (vma = mm->mmap; vma; vma = vma->vm_next) { 6696 struct mm_walk mem_cgroup_count_precharge_walk = { 6697 .pmd_entry = mem_cgroup_count_precharge_pte_range, 6698 .mm = mm, 6699 .private = vma, 6700 }; 6701 if (is_vm_hugetlb_page(vma)) 6702 continue; 6703 walk_page_range(vma->vm_start, vma->vm_end, 6704 &mem_cgroup_count_precharge_walk); 6705 } 6706 up_read(&mm->mmap_sem); 6707 6708 precharge = mc.precharge; 6709 mc.precharge = 0; 6710 6711 return precharge; 6712 } 6713 6714 static int mem_cgroup_precharge_mc(struct mm_struct *mm) 6715 { 6716 unsigned long precharge = mem_cgroup_count_precharge(mm); 6717 6718 VM_BUG_ON(mc.moving_task); 6719 mc.moving_task = current; 6720 return mem_cgroup_do_precharge(precharge); 6721 } 6722 6723 /* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */ 6724 static void __mem_cgroup_clear_mc(void) 6725 { 6726 struct mem_cgroup *from = mc.from; 6727 struct mem_cgroup *to = mc.to; 6728 int i; 6729 6730 /* we must uncharge all the leftover precharges from mc.to */ 6731 if (mc.precharge) { 6732 __mem_cgroup_cancel_charge(mc.to, mc.precharge); 6733 mc.precharge = 0; 6734 } 6735 /* 6736 * we didn't uncharge from mc.from at mem_cgroup_move_account(), so 6737 * we must uncharge here. 6738 */ 6739 if (mc.moved_charge) { 6740 __mem_cgroup_cancel_charge(mc.from, mc.moved_charge); 6741 mc.moved_charge = 0; 6742 } 6743 /* we must fixup refcnts and charges */ 6744 if (mc.moved_swap) { 6745 /* uncharge swap account from the old cgroup */ 6746 if (!mem_cgroup_is_root(mc.from)) 6747 res_counter_uncharge(&mc.from->memsw, 6748 PAGE_SIZE * mc.moved_swap); 6749 6750 for (i = 0; i < mc.moved_swap; i++) 6751 css_put(&mc.from->css); 6752 6753 if (!mem_cgroup_is_root(mc.to)) { 6754 /* 6755 * we charged both to->res and to->memsw, so we should 6756 * uncharge to->res. 6757 */ 6758 res_counter_uncharge(&mc.to->res, 6759 PAGE_SIZE * mc.moved_swap); 6760 } 6761 /* we've already done css_get(mc.to) */ 6762 mc.moved_swap = 0; 6763 } 6764 memcg_oom_recover(from); 6765 memcg_oom_recover(to); 6766 wake_up_all(&mc.waitq); 6767 } 6768 6769 static void mem_cgroup_clear_mc(void) 6770 { 6771 struct mem_cgroup *from = mc.from; 6772 6773 /* 6774 * we must clear moving_task before waking up waiters at the end of 6775 * task migration. 6776 */ 6777 mc.moving_task = NULL; 6778 __mem_cgroup_clear_mc(); 6779 spin_lock(&mc.lock); 6780 mc.from = NULL; 6781 mc.to = NULL; 6782 spin_unlock(&mc.lock); 6783 mem_cgroup_end_move(from); 6784 } 6785 6786 static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, 6787 struct cgroup_taskset *tset) 6788 { 6789 struct task_struct *p = cgroup_taskset_first(tset); 6790 int ret = 0; 6791 struct mem_cgroup *memcg = mem_cgroup_from_css(css); 6792 unsigned long move_charge_at_immigrate; 6793 6794 /* 6795 * We are now commited to this value whatever it is. Changes in this 6796 * tunable will only affect upcoming migrations, not the current one. 6797 * So we need to save it, and keep it going. 6798 */ 6799 move_charge_at_immigrate = memcg->move_charge_at_immigrate; 6800 if (move_charge_at_immigrate) { 6801 struct mm_struct *mm; 6802 struct mem_cgroup *from = mem_cgroup_from_task(p); 6803 6804 VM_BUG_ON(from == memcg); 6805 6806 mm = get_task_mm(p); 6807 if (!mm) 6808 return 0; 6809 /* We move charges only when we move a owner of the mm */ 6810 if (mm->owner == p) { 6811 VM_BUG_ON(mc.from); 6812 VM_BUG_ON(mc.to); 6813 VM_BUG_ON(mc.precharge); 6814 VM_BUG_ON(mc.moved_charge); 6815 VM_BUG_ON(mc.moved_swap); 6816 mem_cgroup_start_move(from); 6817 spin_lock(&mc.lock); 6818 mc.from = from; 6819 mc.to = memcg; 6820 mc.immigrate_flags = move_charge_at_immigrate; 6821 spin_unlock(&mc.lock); 6822 /* We set mc.moving_task later */ 6823 6824 ret = mem_cgroup_precharge_mc(mm); 6825 if (ret) 6826 mem_cgroup_clear_mc(); 6827 } 6828 mmput(mm); 6829 } 6830 return ret; 6831 } 6832 6833 static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css, 6834 struct cgroup_taskset *tset) 6835 { 6836 mem_cgroup_clear_mc(); 6837 } 6838 6839 static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, 6840 unsigned long addr, unsigned long end, 6841 struct mm_walk *walk) 6842 { 6843 int ret = 0; 6844 struct vm_area_struct *vma = walk->private; 6845 pte_t *pte; 6846 spinlock_t *ptl; 6847 enum mc_target_type target_type; 6848 union mc_target target; 6849 struct page *page; 6850 struct page_cgroup *pc; 6851 6852 /* 6853 * We don't take compound_lock() here but no race with splitting thp 6854 * happens because: 6855 * - if pmd_trans_huge_lock() returns 1, the relevant thp is not 6856 * under splitting, which means there's no concurrent thp split, 6857 * - if another thread runs into split_huge_page() just after we 6858 * entered this if-block, the thread must wait for page table lock 6859 * to be unlocked in __split_huge_page_splitting(), where the main 6860 * part of thp split is not executed yet. 6861 */ 6862 if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { 6863 if (mc.precharge < HPAGE_PMD_NR) { 6864 spin_unlock(ptl); 6865 return 0; 6866 } 6867 target_type = get_mctgt_type_thp(vma, addr, *pmd, &target); 6868 if (target_type == MC_TARGET_PAGE) { 6869 page = target.page; 6870 if (!isolate_lru_page(page)) { 6871 pc = lookup_page_cgroup(page); 6872 if (!mem_cgroup_move_account(page, HPAGE_PMD_NR, 6873 pc, mc.from, mc.to)) { 6874 mc.precharge -= HPAGE_PMD_NR; 6875 mc.moved_charge += HPAGE_PMD_NR; 6876 } 6877 putback_lru_page(page); 6878 } 6879 put_page(page); 6880 } 6881 spin_unlock(ptl); 6882 return 0; 6883 } 6884 6885 if (pmd_trans_unstable(pmd)) 6886 return 0; 6887 retry: 6888 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 6889 for (; addr != end; addr += PAGE_SIZE) { 6890 pte_t ptent = *(pte++); 6891 swp_entry_t ent; 6892 6893 if (!mc.precharge) 6894 break; 6895 6896 switch (get_mctgt_type(vma, addr, ptent, &target)) { 6897 case MC_TARGET_PAGE: 6898 page = target.page; 6899 if (isolate_lru_page(page)) 6900 goto put; 6901 pc = lookup_page_cgroup(page); 6902 if (!mem_cgroup_move_account(page, 1, pc, 6903 mc.from, mc.to)) { 6904 mc.precharge--; 6905 /* we uncharge from mc.from later. */ 6906 mc.moved_charge++; 6907 } 6908 putback_lru_page(page); 6909 put: /* get_mctgt_type() gets the page */ 6910 put_page(page); 6911 break; 6912 case MC_TARGET_SWAP: 6913 ent = target.ent; 6914 if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) { 6915 mc.precharge--; 6916 /* we fixup refcnts and charges later. */ 6917 mc.moved_swap++; 6918 } 6919 break; 6920 default: 6921 break; 6922 } 6923 } 6924 pte_unmap_unlock(pte - 1, ptl); 6925 cond_resched(); 6926 6927 if (addr != end) { 6928 /* 6929 * We have consumed all precharges we got in can_attach(). 6930 * We try charge one by one, but don't do any additional 6931 * charges to mc.to if we have failed in charge once in attach() 6932 * phase. 6933 */ 6934 ret = mem_cgroup_do_precharge(1); 6935 if (!ret) 6936 goto retry; 6937 } 6938 6939 return ret; 6940 } 6941 6942 static void mem_cgroup_move_charge(struct mm_struct *mm) 6943 { 6944 struct vm_area_struct *vma; 6945 6946 lru_add_drain_all(); 6947 retry: 6948 if (unlikely(!down_read_trylock(&mm->mmap_sem))) { 6949 /* 6950 * Someone who are holding the mmap_sem might be waiting in 6951 * waitq. So we cancel all extra charges, wake up all waiters, 6952 * and retry. Because we cancel precharges, we might not be able 6953 * to move enough charges, but moving charge is a best-effort 6954 * feature anyway, so it wouldn't be a big problem. 6955 */ 6956 __mem_cgroup_clear_mc(); 6957 cond_resched(); 6958 goto retry; 6959 } 6960 for (vma = mm->mmap; vma; vma = vma->vm_next) { 6961 int ret; 6962 struct mm_walk mem_cgroup_move_charge_walk = { 6963 .pmd_entry = mem_cgroup_move_charge_pte_range, 6964 .mm = mm, 6965 .private = vma, 6966 }; 6967 if (is_vm_hugetlb_page(vma)) 6968 continue; 6969 ret = walk_page_range(vma->vm_start, vma->vm_end, 6970 &mem_cgroup_move_charge_walk); 6971 if (ret) 6972 /* 6973 * means we have consumed all precharges and failed in 6974 * doing additional charge. Just abandon here. 6975 */ 6976 break; 6977 } 6978 up_read(&mm->mmap_sem); 6979 } 6980 6981 static void mem_cgroup_move_task(struct cgroup_subsys_state *css, 6982 struct cgroup_taskset *tset) 6983 { 6984 struct task_struct *p = cgroup_taskset_first(tset); 6985 struct mm_struct *mm = get_task_mm(p); 6986 6987 if (mm) { 6988 if (mc.to) 6989 mem_cgroup_move_charge(mm); 6990 mmput(mm); 6991 } 6992 if (mc.to) 6993 mem_cgroup_clear_mc(); 6994 } 6995 #else /* !CONFIG_MMU */ 6996 static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, 6997 struct cgroup_taskset *tset) 6998 { 6999 return 0; 7000 } 7001 static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css, 7002 struct cgroup_taskset *tset) 7003 { 7004 } 7005 static void mem_cgroup_move_task(struct cgroup_subsys_state *css, 7006 struct cgroup_taskset *tset) 7007 { 7008 } 7009 #endif 7010 7011 /* 7012 * Cgroup retains root cgroups across [un]mount cycles making it necessary 7013 * to verify sane_behavior flag on each mount attempt. 7014 */ 7015 static void mem_cgroup_bind(struct cgroup_subsys_state *root_css) 7016 { 7017 /* 7018 * use_hierarchy is forced with sane_behavior. cgroup core 7019 * guarantees that @root doesn't have any children, so turning it 7020 * on for the root memcg is enough. 7021 */ 7022 if (cgroup_sane_behavior(root_css->cgroup)) 7023 mem_cgroup_from_css(root_css)->use_hierarchy = true; 7024 } 7025 7026 struct cgroup_subsys memory_cgrp_subsys = { 7027 .css_alloc = mem_cgroup_css_alloc, 7028 .css_online = mem_cgroup_css_online, 7029 .css_offline = mem_cgroup_css_offline, 7030 .css_free = mem_cgroup_css_free, 7031 .can_attach = mem_cgroup_can_attach, 7032 .cancel_attach = mem_cgroup_cancel_attach, 7033 .attach = mem_cgroup_move_task, 7034 .bind = mem_cgroup_bind, 7035 .base_cftypes = mem_cgroup_files, 7036 .early_init = 0, 7037 }; 7038 7039 #ifdef CONFIG_MEMCG_SWAP 7040 static int __init enable_swap_account(char *s) 7041 { 7042 if (!strcmp(s, "1")) 7043 really_do_swap_account = 1; 7044 else if (!strcmp(s, "0")) 7045 really_do_swap_account = 0; 7046 return 1; 7047 } 7048 __setup("swapaccount=", enable_swap_account); 7049 7050 static void __init memsw_file_init(void) 7051 { 7052 WARN_ON(cgroup_add_cftypes(&memory_cgrp_subsys, memsw_cgroup_files)); 7053 } 7054 7055 static void __init enable_swap_cgroup(void) 7056 { 7057 if (!mem_cgroup_disabled() && really_do_swap_account) { 7058 do_swap_account = 1; 7059 memsw_file_init(); 7060 } 7061 } 7062 7063 #else 7064 static void __init enable_swap_cgroup(void) 7065 { 7066 } 7067 #endif 7068 7069 /* 7070 * subsys_initcall() for memory controller. 7071 * 7072 * Some parts like hotcpu_notifier() have to be initialized from this context 7073 * because of lock dependencies (cgroup_lock -> cpu hotplug) but basically 7074 * everything that doesn't depend on a specific mem_cgroup structure should 7075 * be initialized from here. 7076 */ 7077 static int __init mem_cgroup_init(void) 7078 { 7079 hotcpu_notifier(memcg_cpu_hotplug_callback, 0); 7080 enable_swap_cgroup(); 7081 mem_cgroup_soft_limit_tree_init(); 7082 memcg_stock_init(); 7083 return 0; 7084 } 7085 subsys_initcall(mem_cgroup_init); 7086