mm/list_lru.c

   1 /*
   2  * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
   3  * Authors: David Chinner and Glauber Costa
   4  *
   5  * Generic LRU infrastructure
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/list_lru.h>
  11 #include <linux/slab.h>
  12 #include <linux/mutex.h>
  13 #include <linux/memcontrol.h>
  14
  15 #ifdef CONFIG_MEMCG_KMEM
  16 static LIST_HEAD(list_lrus);
  17 static DEFINE_MUTEX(list_lrus_mutex);
  18
  19 static void list_lru_register(struct list_lru *lru)
  20 {
  21         mutex_lock(&list_lrus_mutex);
  22         list_add(&lru->list, &list_lrus);
  23         mutex_unlock(&list_lrus_mutex);
  24 }
  25
  26 static void list_lru_unregister(struct list_lru *lru)
  27 {
  28         mutex_lock(&list_lrus_mutex);
  29         list_del(&lru->list);
  30         mutex_unlock(&list_lrus_mutex);
  31 }
  32
  33 static int lru_shrinker_id(struct list_lru *lru)
  34 {
  35         return lru->shrinker_id;
  36 }
  37
  38 static inline bool list_lru_memcg_aware(struct list_lru *lru)
  39 {
  40         return lru->memcg_aware;
  41 }
  42
  43 static inline struct list_lru_one *
  44 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
  45 {
  46         struct list_lru_memcg *memcg_lrus;
  47         /*
  48          * Either lock or RCU protects the array of per cgroup lists
  49          * from relocation (see memcg_update_list_lru_node).
  50          */
  51         memcg_lrus = rcu_dereference_check(nlru->memcg_lrus,
  52                                            lockdep_is_held(&nlru->lock));
  53         if (memcg_lrus && idx >= 0)
  54                 return memcg_lrus->lru[idx];
  55         return &nlru->lru;
  56 }
  57
  58 static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
  59 {
  60         struct page *page;
  61
  62         if (!memcg_kmem_enabled())
  63                 return NULL;
  64         page = virt_to_head_page(ptr);
  65         return page->mem_cgroup;
  66 }
  67
  68 static inline struct list_lru_one *
  69 list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
  70                    struct mem_cgroup **memcg_ptr)
  71 {
  72         struct list_lru_one *l = &nlru->lru;
  73         struct mem_cgroup *memcg = NULL;
  74
  75         if (!nlru->memcg_lrus)
  76                 goto out;
  77
  78         memcg = mem_cgroup_from_kmem(ptr);
  79         if (!memcg)
  80                 goto out;
  81
  82         l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
  83 out:
  84         if (memcg_ptr)
  85                 *memcg_ptr = memcg;
  86         return l;
  87 }
  88 #else
  89 static void list_lru_register(struct list_lru *lru)
  90 {
  91 }
  92
  93 static void list_lru_unregister(struct list_lru *lru)
  94 {
  95 }
  96
  97 static int lru_shrinker_id(struct list_lru *lru)
  98 {
  99         return -1;
 100 }
 101
 102 static inline bool list_lru_memcg_aware(struct list_lru *lru)
 103 {
 104         return false;
 105 }
 106
 107 static inline struct list_lru_one *
 108 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
 109 {
 110         return &nlru->lru;
 111 }
 112
 113 static inline struct list_lru_one *
 114 list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
 115                    struct mem_cgroup **memcg_ptr)
 116 {
 117         if (memcg_ptr)
 118                 *memcg_ptr = NULL;
 119         return &nlru->lru;
 120 }
 121 #endif /* CONFIG_MEMCG_KMEM */
 122
 123 bool list_lru_add(struct list_lru *lru, struct list_head *item)
 124 {
 125         int nid = page_to_nid(virt_to_page(item));
 126         struct list_lru_node *nlru = &lru->node[nid];
 127         struct mem_cgroup *memcg;
 128         struct list_lru_one *l;
 129
 130         spin_lock(&nlru->lock);
 131         if (list_empty(item)) {
 132                 l = list_lru_from_kmem(nlru, item, &memcg);
 133                 list_add_tail(item, &l->list);
 134                 /* Set shrinker bit if the first element was added */
 135                 if (!l->nr_items++)
 136                         memcg_set_shrinker_bit(memcg, nid,
 137                                                lru_shrinker_id(lru));
 138                 nlru->nr_items++;
 139                 spin_unlock(&nlru->lock);
 140                 return true;
 141         }
 142         spin_unlock(&nlru->lock);
 143         return false;
 144 }
 145 EXPORT_SYMBOL_GPL(list_lru_add);
 146
 147 bool list_lru_del(struct list_lru *lru, struct list_head *item)
 148 {
 149         int nid = page_to_nid(virt_to_page(item));
 150         struct list_lru_node *nlru = &lru->node[nid];
 151         struct list_lru_one *l;
 152
 153         spin_lock(&nlru->lock);
 154         if (!list_empty(item)) {
 155                 l = list_lru_from_kmem(nlru, item, NULL);
 156                 list_del_init(item);
 157                 l->nr_items--;
 158                 nlru->nr_items--;
 159                 spin_unlock(&nlru->lock);
 160                 return true;
 161         }
 162         spin_unlock(&nlru->lock);
 163         return false;
 164 }
 165 EXPORT_SYMBOL_GPL(list_lru_del);
 166
 167 void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
 168 {
 169         list_del_init(item);
 170         list->nr_items--;
 171 }
 172 EXPORT_SYMBOL_GPL(list_lru_isolate);
 173
 174 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
 175                            struct list_head *head)
 176 {
 177         list_move(item, head);
 178         list->nr_items--;
 179 }
 180 EXPORT_SYMBOL_GPL(list_lru_isolate_move);
 181
 182 unsigned long list_lru_count_one(struct list_lru *lru,
 183                                  int nid, struct mem_cgroup *memcg)
 184 {
 185         struct list_lru_node *nlru = &lru->node[nid];
 186         struct list_lru_one *l;
 187         unsigned long count;
 188
 189         rcu_read_lock();
 190         l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
 191         count = l->nr_items;
 192         rcu_read_unlock();
 193
 194         return count;
 195 }
 196 EXPORT_SYMBOL_GPL(list_lru_count_one);
 197
 198 unsigned long list_lru_count_node(struct list_lru *lru, int nid)
 199 {
 200         struct list_lru_node *nlru;
 201
 202         nlru = &lru->node[nid];
 203         return nlru->nr_items;
 204 }
 205 EXPORT_SYMBOL_GPL(list_lru_count_node);
 206
 207 static unsigned long
 208 __list_lru_walk_one(struct list_lru_node *nlru, int memcg_idx,
 209                     list_lru_walk_cb isolate, void *cb_arg,
 210                     unsigned long *nr_to_walk)
 211 {
 212
 213         struct list_lru_one *l;
 214         struct list_head *item, *n;
 215         unsigned long isolated = 0;
 216
 217         l = list_lru_from_memcg_idx(nlru, memcg_idx);
 218 restart:
 219         list_for_each_safe(item, n, &l->list) {
 220                 enum lru_status ret;
 221
 222                 /*
 223                  * decrement nr_to_walk first so that we don't livelock if we
 224                  * get stuck on large numbesr of LRU_RETRY items
 225                  */
 226                 if (!*nr_to_walk)
 227                         break;
 228                 --*nr_to_walk;
 229
 230                 ret = isolate(item, l, &nlru->lock, cb_arg);
 231                 switch (ret) {
 232                 case LRU_REMOVED_RETRY:
 233                         assert_spin_locked(&nlru->lock);
 234                         /* fall through */
 235                 case LRU_REMOVED:
 236                         isolated++;
 237                         nlru->nr_items--;
 238                         /*
 239                          * If the lru lock has been dropped, our list
 240                          * traversal is now invalid and so we have to
 241                          * restart from scratch.
 242                          */
 243                         if (ret == LRU_REMOVED_RETRY)
 244                                 goto restart;
 245                         break;
 246                 case LRU_ROTATE:
 247                         list_move_tail(item, &l->list);
 248                         break;
 249                 case LRU_SKIP:
 250                         break;
 251                 case LRU_RETRY:
 252                         /*
 253                          * The lru lock has been dropped, our list traversal is
 254                          * now invalid and so we have to restart from scratch.
 255                          */
 256                         assert_spin_locked(&nlru->lock);
 257                         goto restart;
 258                 default:
 259                         BUG();
 260                 }
 261         }
 262         return isolated;
 263 }
 264
 265 unsigned long
 266 list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
 267                   list_lru_walk_cb isolate, void *cb_arg,
 268                   unsigned long *nr_to_walk)
 269 {
 270         struct list_lru_node *nlru = &lru->node[nid];
 271         unsigned long ret;
 272
 273         spin_lock(&nlru->lock);
 274         ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,
 275                                   nr_to_walk);
 276         spin_unlock(&nlru->lock);
 277         return ret;
 278 }
 279 EXPORT_SYMBOL_GPL(list_lru_walk_one);
 280
 281 unsigned long
 282 list_lru_walk_one_irq(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
 283                       list_lru_walk_cb isolate, void *cb_arg,
 284                       unsigned long *nr_to_walk)
 285 {
 286         struct list_lru_node *nlru = &lru->node[nid];
 287         unsigned long ret;
 288
 289         spin_lock_irq(&nlru->lock);
 290         ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,
 291                                   nr_to_walk);
 292         spin_unlock_irq(&nlru->lock);
 293         return ret;
 294 }
 295
 296 unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
 297                                  list_lru_walk_cb isolate, void *cb_arg,
 298                                  unsigned long *nr_to_walk)
 299 {
 300         long isolated = 0;
 301         int memcg_idx;
 302
 303         isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
 304                                       nr_to_walk);
 305         if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
 306                 for_each_memcg_cache_index(memcg_idx) {
 307                         struct list_lru_node *nlru = &lru->node[nid];
 308
 309                         spin_lock(&nlru->lock);
 310                         isolated += __list_lru_walk_one(nlru, memcg_idx,
 311                                                         isolate, cb_arg,
 312                                                         nr_to_walk);
 313                         spin_unlock(&nlru->lock);
 314
 315                         if (*nr_to_walk <= 0)
 316                                 break;
 317                 }
 318         }
 319         return isolated;
 320 }
 321 EXPORT_SYMBOL_GPL(list_lru_walk_node);
 322
 323 static void init_one_lru(struct list_lru_one *l)
 324 {
 325         INIT_LIST_HEAD(&l->list);
 326         l->nr_items = 0;
 327 }
 328
 329 #ifdef CONFIG_MEMCG_KMEM
 330 static void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus,
 331                                           int begin, int end)
 332 {
 333         int i;
 334
 335         for (i = begin; i < end; i++)
 336                 kfree(memcg_lrus->lru[i]);
 337 }
 338
 339 static int __memcg_init_list_lru_node(struct list_lru_memcg *memcg_lrus,
 340                                       int begin, int end)
 341 {
 342         int i;
 343
 344         for (i = begin; i < end; i++) {
 345                 struct list_lru_one *l;
 346
 347                 l = kmalloc(sizeof(struct list_lru_one), GFP_KERNEL);
 348                 if (!l)
 349                         goto fail;
 350
 351                 init_one_lru(l);
 352                 memcg_lrus->lru[i] = l;
 353         }
 354         return 0;
 355 fail:
 356         __memcg_destroy_list_lru_node(memcg_lrus, begin, i);
 357         return -ENOMEM;
 358 }
 359
 360 static int memcg_init_list_lru_node(struct list_lru_node *nlru)
 361 {
 362         struct list_lru_memcg *memcg_lrus;
 363         int size = memcg_nr_cache_ids;
 364
 365         memcg_lrus = kvmalloc(sizeof(*memcg_lrus) +
 366                               size * sizeof(void *), GFP_KERNEL);
 367         if (!memcg_lrus)
 368                 return -ENOMEM;
 369
 370         if (__memcg_init_list_lru_node(memcg_lrus, 0, size)) {
 371                 kvfree(memcg_lrus);
 372                 return -ENOMEM;
 373         }
 374         RCU_INIT_POINTER(nlru->memcg_lrus, memcg_lrus);
 375
 376         return 0;
 377 }
 378
 379 static void memcg_destroy_list_lru_node(struct list_lru_node *nlru)
 380 {
 381         struct list_lru_memcg *memcg_lrus;
 382         /*
 383          * This is called when shrinker has already been unregistered,
 384          * and nobody can use it. So, there is no need to use kvfree_rcu().
 385          */
 386         memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, true);
 387         __memcg_destroy_list_lru_node(memcg_lrus, 0, memcg_nr_cache_ids);
 388         kvfree(memcg_lrus);
 389 }
 390
 391 static void kvfree_rcu(struct rcu_head *head)
 392 {
 393         struct list_lru_memcg *mlru;
 394
 395         mlru = container_of(head, struct list_lru_memcg, rcu);
 396         kvfree(mlru);
 397 }
 398
 399 static int memcg_update_list_lru_node(struct list_lru_node *nlru,
 400                                       int old_size, int new_size)
 401 {
 402         struct list_lru_memcg *old, *new;
 403
 404         BUG_ON(old_size > new_size);
 405
 406         old = rcu_dereference_protected(nlru->memcg_lrus,
 407                                         lockdep_is_held(&list_lrus_mutex));
 408         new = kvmalloc(sizeof(*new) + new_size * sizeof(void *), GFP_KERNEL);
 409         if (!new)
 410                 return -ENOMEM;
 411
 412         if (__memcg_init_list_lru_node(new, old_size, new_size)) {
 413                 kvfree(new);
 414                 return -ENOMEM;
 415         }
 416
 417         memcpy(&new->lru, &old->lru, old_size * sizeof(void *));
 418
 419         /*
 420          * The locking below allows readers that hold nlru->lock avoid taking
 421          * rcu_read_lock (see list_lru_from_memcg_idx).
 422          *
 423          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
 424          * we have to use IRQ-safe primitives here to avoid deadlock.
 425          */
 426         spin_lock_irq(&nlru->lock);
 427         rcu_assign_pointer(nlru->memcg_lrus, new);
 428         spin_unlock_irq(&nlru->lock);
 429
 430         call_rcu(&old->rcu, kvfree_rcu);
 431         return 0;
 432 }
 433
 434 static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru,
 435                                               int old_size, int new_size)
 436 {
 437         struct list_lru_memcg *memcg_lrus;
 438
 439         memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus,
 440                                                lockdep_is_held(&list_lrus_mutex));
 441         /* do not bother shrinking the array back to the old size, because we
 442          * cannot handle allocation failures here */
 443         __memcg_destroy_list_lru_node(memcg_lrus, old_size, new_size);
 444 }
 445
 446 static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
 447 {
 448         int i;
 449
 450         lru->memcg_aware = memcg_aware;
 451
 452         if (!memcg_aware)
 453                 return 0;
 454
 455         for_each_node(i) {
 456                 if (memcg_init_list_lru_node(&lru->node[i]))
 457                         goto fail;
 458         }
 459         return 0;
 460 fail:
 461         for (i = i - 1; i >= 0; i--) {
 462                 if (!lru->node[i].memcg_lrus)
 463                         continue;
 464                 memcg_destroy_list_lru_node(&lru->node[i]);
 465         }
 466         return -ENOMEM;
 467 }
 468
 469 static void memcg_destroy_list_lru(struct list_lru *lru)
 470 {
 471         int i;
 472
 473         if (!list_lru_memcg_aware(lru))
 474                 return;
 475
 476         for_each_node(i)
 477                 memcg_destroy_list_lru_node(&lru->node[i]);
 478 }
 479
 480 static int memcg_update_list_lru(struct list_lru *lru,
 481                                  int old_size, int new_size)
 482 {
 483         int i;
 484
 485         if (!list_lru_memcg_aware(lru))
 486                 return 0;
 487
 488         for_each_node(i) {
 489                 if (memcg_update_list_lru_node(&lru->node[i],
 490                                                old_size, new_size))
 491                         goto fail;
 492         }
 493         return 0;
 494 fail:
 495         for (i = i - 1; i >= 0; i--) {
 496                 if (!lru->node[i].memcg_lrus)
 497                         continue;
 498
 499                 memcg_cancel_update_list_lru_node(&lru->node[i],
 500                                                   old_size, new_size);
 501         }
 502         return -ENOMEM;
 503 }
 504
 505 static void memcg_cancel_update_list_lru(struct list_lru *lru,
 506                                          int old_size, int new_size)
 507 {
 508         int i;
 509
 510         if (!list_lru_memcg_aware(lru))
 511                 return;
 512
 513         for_each_node(i)
 514                 memcg_cancel_update_list_lru_node(&lru->node[i],
 515                                                   old_size, new_size);
 516 }
 517
 518 int memcg_update_all_list_lrus(int new_size)
 519 {
 520         int ret = 0;
 521         struct list_lru *lru;
 522         int old_size = memcg_nr_cache_ids;
 523
 524         mutex_lock(&list_lrus_mutex);
 525         list_for_each_entry(lru, &list_lrus, list) {
 526                 ret = memcg_update_list_lru(lru, old_size, new_size);
 527                 if (ret)
 528                         goto fail;
 529         }
 530 out:
 531         mutex_unlock(&list_lrus_mutex);
 532         return ret;
 533 fail:
 534         list_for_each_entry_continue_reverse(lru, &list_lrus, list)
 535                 memcg_cancel_update_list_lru(lru, old_size, new_size);
 536         goto out;
 537 }
 538
 539 static void memcg_drain_list_lru_node(struct list_lru *lru, int nid,
 540                                       int src_idx, struct mem_cgroup *dst_memcg)
 541 {
 542         struct list_lru_node *nlru = &lru->node[nid];
 543         int dst_idx = dst_memcg->kmemcg_id;
 544         struct list_lru_one *src, *dst;
 545         bool set;
 546
 547         /*
 548          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
 549          * we have to use IRQ-safe primitives here to avoid deadlock.
 550          */
 551         spin_lock_irq(&nlru->lock);
 552
 553         src = list_lru_from_memcg_idx(nlru, src_idx);
 554         dst = list_lru_from_memcg_idx(nlru, dst_idx);
 555
 556         list_splice_init(&src->list, &dst->list);
 557         set = (!dst->nr_items && src->nr_items);
 558         dst->nr_items += src->nr_items;
 559         if (set)
 560                 memcg_set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
 561         src->nr_items = 0;
 562
 563         spin_unlock_irq(&nlru->lock);
 564 }
 565
 566 static void memcg_drain_list_lru(struct list_lru *lru,
 567                                  int src_idx, struct mem_cgroup *dst_memcg)
 568 {
 569         int i;
 570
 571         if (!list_lru_memcg_aware(lru))
 572                 return;
 573
 574         for_each_node(i)
 575                 memcg_drain_list_lru_node(lru, i, src_idx, dst_memcg);
 576 }
 577
 578 void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg)
 579 {
 580         struct list_lru *lru;
 581
 582         mutex_lock(&list_lrus_mutex);
 583         list_for_each_entry(lru, &list_lrus, list)
 584                 memcg_drain_list_lru(lru, src_idx, dst_memcg);
 585         mutex_unlock(&list_lrus_mutex);
 586 }
 587 #else
 588 static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
 589 {
 590         return 0;
 591 }
 592
 593 static void memcg_destroy_list_lru(struct list_lru *lru)
 594 {
 595 }
 596 #endif /* CONFIG_MEMCG_KMEM */
 597
 598 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
 599                     struct lock_class_key *key, struct shrinker *shrinker)
 600 {
 601         int i;
 602         size_t size = sizeof(*lru->node) * nr_node_ids;
 603         int err = -ENOMEM;
 604
 605 #ifdef CONFIG_MEMCG_KMEM
 606         if (shrinker)
 607                 lru->shrinker_id = shrinker->id;
 608         else
 609                 lru->shrinker_id = -1;
 610 #endif
 611         memcg_get_cache_ids();
 612
 613         lru->node = kzalloc(size, GFP_KERNEL);
 614         if (!lru->node)
 615                 goto out;
 616
 617         for_each_node(i) {
 618                 spin_lock_init(&lru->node[i].lock);
 619                 if (key)
 620                         lockdep_set_class(&lru->node[i].lock, key);
 621                 init_one_lru(&lru->node[i].lru);
 622         }
 623
 624         err = memcg_init_list_lru(lru, memcg_aware);
 625         if (err) {
 626                 kfree(lru->node);
 627                 /* Do this so a list_lru_destroy() doesn't crash: */
 628                 lru->node = NULL;
 629                 goto out;
 630         }
 631
 632         list_lru_register(lru);
 633 out:
 634         memcg_put_cache_ids();
 635         return err;
 636 }
 637 EXPORT_SYMBOL_GPL(__list_lru_init);
 638
 639 void list_lru_destroy(struct list_lru *lru)
 640 {
 641         /* Already destroyed or not yet initialized? */
 642         if (!lru->node)
 643                 return;
 644
 645         memcg_get_cache_ids();
 646
 647         list_lru_unregister(lru);
 648
 649         memcg_destroy_list_lru(lru);
 650         kfree(lru->node);
 651         lru->node = NULL;
 652
 653 #ifdef CONFIG_MEMCG_KMEM
 654         lru->shrinker_id = -1;
 655 #endif
 656         memcg_put_cache_ids();
 657 }
 658 EXPORT_SYMBOL_GPL(list_lru_destroy);