mm/list_lru.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
   4  * Authors: David Chinner and Glauber Costa
   5  *
   6  * Generic LRU infrastructure
   7  */
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/mm.h>
  11 #include <linux/list_lru.h>
  12 #include <linux/slab.h>
  13 #include <linux/mutex.h>
  14 #include <linux/memcontrol.h>
  15
  16 #ifdef CONFIG_MEMCG_KMEM
  17 static LIST_HEAD(list_lrus);
  18 static DEFINE_MUTEX(list_lrus_mutex);
  19
  20 static void list_lru_register(struct list_lru *lru)
  21 {
  22         mutex_lock(&list_lrus_mutex);
  23         list_add(&lru->list, &list_lrus);
  24         mutex_unlock(&list_lrus_mutex);
  25 }
  26
  27 static void list_lru_unregister(struct list_lru *lru)
  28 {
  29         mutex_lock(&list_lrus_mutex);
  30         list_del(&lru->list);
  31         mutex_unlock(&list_lrus_mutex);
  32 }
  33
  34 static int lru_shrinker_id(struct list_lru *lru)
  35 {
  36         return lru->shrinker_id;
  37 }
  38
  39 static inline bool list_lru_memcg_aware(struct list_lru *lru)
  40 {
  41         return lru->memcg_aware;
  42 }
  43
  44 static inline struct list_lru_one *
  45 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
  46 {
  47         struct list_lru_memcg *memcg_lrus;
  48         /*
  49          * Either lock or RCU protects the array of per cgroup lists
  50          * from relocation (see memcg_update_list_lru_node).
  51          */
  52         memcg_lrus = rcu_dereference_check(nlru->memcg_lrus,
  53                                            lockdep_is_held(&nlru->lock));
  54         if (memcg_lrus && idx >= 0)
  55                 return memcg_lrus->lru[idx];
  56         return &nlru->lru;
  57 }
  58
  59 static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
  60 {
  61         struct page *page;
  62
  63         if (!memcg_kmem_enabled())
  64                 return NULL;
  65         page = virt_to_head_page(ptr);
  66         return page->mem_cgroup;
  67 }
  68
  69 static inline struct list_lru_one *
  70 list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
  71                    struct mem_cgroup **memcg_ptr)
  72 {
  73         struct list_lru_one *l = &nlru->lru;
  74         struct mem_cgroup *memcg = NULL;
  75
  76         if (!nlru->memcg_lrus)
  77                 goto out;
  78
  79         memcg = mem_cgroup_from_kmem(ptr);
  80         if (!memcg)
  81                 goto out;
  82
  83         l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
  84 out:
  85         if (memcg_ptr)
  86                 *memcg_ptr = memcg;
  87         return l;
  88 }
  89 #else
  90 static void list_lru_register(struct list_lru *lru)
  91 {
  92 }
  93
  94 static void list_lru_unregister(struct list_lru *lru)
  95 {
  96 }
  97
  98 static int lru_shrinker_id(struct list_lru *lru)
  99 {
 100         return -1;
 101 }
 102
 103 static inline bool list_lru_memcg_aware(struct list_lru *lru)
 104 {
 105         return false;
 106 }
 107
 108 static inline struct list_lru_one *
 109 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
 110 {
 111         return &nlru->lru;
 112 }
 113
 114 static inline struct list_lru_one *
 115 list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
 116                    struct mem_cgroup **memcg_ptr)
 117 {
 118         if (memcg_ptr)
 119                 *memcg_ptr = NULL;
 120         return &nlru->lru;
 121 }
 122 #endif /* CONFIG_MEMCG_KMEM */
 123
 124 bool list_lru_add(struct list_lru *lru, struct list_head *item)
 125 {
 126         int nid = page_to_nid(virt_to_page(item));
 127         struct list_lru_node *nlru = &lru->node[nid];
 128         struct mem_cgroup *memcg;
 129         struct list_lru_one *l;
 130
 131         spin_lock(&nlru->lock);
 132         if (list_empty(item)) {
 133                 l = list_lru_from_kmem(nlru, item, &memcg);
 134                 list_add_tail(item, &l->list);
 135                 /* Set shrinker bit if the first element was added */
 136                 if (!l->nr_items++)
 137                         memcg_set_shrinker_bit(memcg, nid,
 138                                                lru_shrinker_id(lru));
 139                 nlru->nr_items++;
 140                 spin_unlock(&nlru->lock);
 141                 return true;
 142         }
 143         spin_unlock(&nlru->lock);
 144         return false;
 145 }
 146 EXPORT_SYMBOL_GPL(list_lru_add);
 147
 148 bool list_lru_del(struct list_lru *lru, struct list_head *item)
 149 {
 150         int nid = page_to_nid(virt_to_page(item));
 151         struct list_lru_node *nlru = &lru->node[nid];
 152         struct list_lru_one *l;
 153
 154         spin_lock(&nlru->lock);
 155         if (!list_empty(item)) {
 156                 l = list_lru_from_kmem(nlru, item, NULL);
 157                 list_del_init(item);
 158                 l->nr_items--;
 159                 nlru->nr_items--;
 160                 spin_unlock(&nlru->lock);
 161                 return true;
 162         }
 163         spin_unlock(&nlru->lock);
 164         return false;
 165 }
 166 EXPORT_SYMBOL_GPL(list_lru_del);
 167
 168 void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
 169 {
 170         list_del_init(item);
 171         list->nr_items--;
 172 }
 173 EXPORT_SYMBOL_GPL(list_lru_isolate);
 174
 175 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
 176                            struct list_head *head)
 177 {
 178         list_move(item, head);
 179         list->nr_items--;
 180 }
 181 EXPORT_SYMBOL_GPL(list_lru_isolate_move);
 182
 183 unsigned long list_lru_count_one(struct list_lru *lru,
 184                                  int nid, struct mem_cgroup *memcg)
 185 {
 186         struct list_lru_node *nlru = &lru->node[nid];
 187         struct list_lru_one *l;
 188         unsigned long count;
 189
 190         rcu_read_lock();
 191         l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
 192         count = l->nr_items;
 193         rcu_read_unlock();
 194
 195         return count;
 196 }
 197 EXPORT_SYMBOL_GPL(list_lru_count_one);
 198
 199 unsigned long list_lru_count_node(struct list_lru *lru, int nid)
 200 {
 201         struct list_lru_node *nlru;
 202
 203         nlru = &lru->node[nid];
 204         return nlru->nr_items;
 205 }
 206 EXPORT_SYMBOL_GPL(list_lru_count_node);
 207
 208 static unsigned long
 209 __list_lru_walk_one(struct list_lru_node *nlru, int memcg_idx,
 210                     list_lru_walk_cb isolate, void *cb_arg,
 211                     unsigned long *nr_to_walk)
 212 {
 213
 214         struct list_lru_one *l;
 215         struct list_head *item, *n;
 216         unsigned long isolated = 0;
 217
 218         l = list_lru_from_memcg_idx(nlru, memcg_idx);
 219 restart:
 220         list_for_each_safe(item, n, &l->list) {
 221                 enum lru_status ret;
 222
 223                 /*
 224                  * decrement nr_to_walk first so that we don't livelock if we
 225                  * get stuck on large numbesr of LRU_RETRY items
 226                  */
 227                 if (!*nr_to_walk)
 228                         break;
 229                 --*nr_to_walk;
 230
 231                 ret = isolate(item, l, &nlru->lock, cb_arg);
 232                 switch (ret) {
 233                 case LRU_REMOVED_RETRY:
 234                         assert_spin_locked(&nlru->lock);
 235                         /* fall through */
 236                 case LRU_REMOVED:
 237                         isolated++;
 238                         nlru->nr_items--;
 239                         /*
 240                          * If the lru lock has been dropped, our list
 241                          * traversal is now invalid and so we have to
 242                          * restart from scratch.
 243                          */
 244                         if (ret == LRU_REMOVED_RETRY)
 245                                 goto restart;
 246                         break;
 247                 case LRU_ROTATE:
 248                         list_move_tail(item, &l->list);
 249                         break;
 250                 case LRU_SKIP:
 251                         break;
 252                 case LRU_RETRY:
 253                         /*
 254                          * The lru lock has been dropped, our list traversal is
 255                          * now invalid and so we have to restart from scratch.
 256                          */
 257                         assert_spin_locked(&nlru->lock);
 258                         goto restart;
 259                 default:
 260                         BUG();
 261                 }
 262         }
 263         return isolated;
 264 }
 265
 266 unsigned long
 267 list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
 268                   list_lru_walk_cb isolate, void *cb_arg,
 269                   unsigned long *nr_to_walk)
 270 {
 271         struct list_lru_node *nlru = &lru->node[nid];
 272         unsigned long ret;
 273
 274         spin_lock(&nlru->lock);
 275         ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,
 276                                   nr_to_walk);
 277         spin_unlock(&nlru->lock);
 278         return ret;
 279 }
 280 EXPORT_SYMBOL_GPL(list_lru_walk_one);
 281
 282 unsigned long
 283 list_lru_walk_one_irq(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
 284                       list_lru_walk_cb isolate, void *cb_arg,
 285                       unsigned long *nr_to_walk)
 286 {
 287         struct list_lru_node *nlru = &lru->node[nid];
 288         unsigned long ret;
 289
 290         spin_lock_irq(&nlru->lock);
 291         ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,
 292                                   nr_to_walk);
 293         spin_unlock_irq(&nlru->lock);
 294         return ret;
 295 }
 296
 297 unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
 298                                  list_lru_walk_cb isolate, void *cb_arg,
 299                                  unsigned long *nr_to_walk)
 300 {
 301         long isolated = 0;
 302         int memcg_idx;
 303
 304         isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
 305                                       nr_to_walk);
 306         if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
 307                 for_each_memcg_cache_index(memcg_idx) {
 308                         struct list_lru_node *nlru = &lru->node[nid];
 309
 310                         spin_lock(&nlru->lock);
 311                         isolated += __list_lru_walk_one(nlru, memcg_idx,
 312                                                         isolate, cb_arg,
 313                                                         nr_to_walk);
 314                         spin_unlock(&nlru->lock);
 315
 316                         if (*nr_to_walk <= 0)
 317                                 break;
 318                 }
 319         }
 320         return isolated;
 321 }
 322 EXPORT_SYMBOL_GPL(list_lru_walk_node);
 323
 324 static void init_one_lru(struct list_lru_one *l)
 325 {
 326         INIT_LIST_HEAD(&l->list);
 327         l->nr_items = 0;
 328 }
 329
 330 #ifdef CONFIG_MEMCG_KMEM
 331 static void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus,
 332                                           int begin, int end)
 333 {
 334         int i;
 335
 336         for (i = begin; i < end; i++)
 337                 kfree(memcg_lrus->lru[i]);
 338 }
 339
 340 static int __memcg_init_list_lru_node(struct list_lru_memcg *memcg_lrus,
 341                                       int begin, int end)
 342 {
 343         int i;
 344
 345         for (i = begin; i < end; i++) {
 346                 struct list_lru_one *l;
 347
 348                 l = kmalloc(sizeof(struct list_lru_one), GFP_KERNEL);
 349                 if (!l)
 350                         goto fail;
 351
 352                 init_one_lru(l);
 353                 memcg_lrus->lru[i] = l;
 354         }
 355         return 0;
 356 fail:
 357         __memcg_destroy_list_lru_node(memcg_lrus, begin, i);
 358         return -ENOMEM;
 359 }
 360
 361 static int memcg_init_list_lru_node(struct list_lru_node *nlru)
 362 {
 363         struct list_lru_memcg *memcg_lrus;
 364         int size = memcg_nr_cache_ids;
 365
 366         memcg_lrus = kvmalloc(sizeof(*memcg_lrus) +
 367                               size * sizeof(void *), GFP_KERNEL);
 368         if (!memcg_lrus)
 369                 return -ENOMEM;
 370
 371         if (__memcg_init_list_lru_node(memcg_lrus, 0, size)) {
 372                 kvfree(memcg_lrus);
 373                 return -ENOMEM;
 374         }
 375         RCU_INIT_POINTER(nlru->memcg_lrus, memcg_lrus);
 376
 377         return 0;
 378 }
 379
 380 static void memcg_destroy_list_lru_node(struct list_lru_node *nlru)
 381 {
 382         struct list_lru_memcg *memcg_lrus;
 383         /*
 384          * This is called when shrinker has already been unregistered,
 385          * and nobody can use it. So, there is no need to use kvfree_rcu().
 386          */
 387         memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, true);
 388         __memcg_destroy_list_lru_node(memcg_lrus, 0, memcg_nr_cache_ids);
 389         kvfree(memcg_lrus);
 390 }
 391
 392 static void kvfree_rcu(struct rcu_head *head)
 393 {
 394         struct list_lru_memcg *mlru;
 395
 396         mlru = container_of(head, struct list_lru_memcg, rcu);
 397         kvfree(mlru);
 398 }
 399
 400 static int memcg_update_list_lru_node(struct list_lru_node *nlru,
 401                                       int old_size, int new_size)
 402 {
 403         struct list_lru_memcg *old, *new;
 404
 405         BUG_ON(old_size > new_size);
 406
 407         old = rcu_dereference_protected(nlru->memcg_lrus,
 408                                         lockdep_is_held(&list_lrus_mutex));
 409         new = kvmalloc(sizeof(*new) + new_size * sizeof(void *), GFP_KERNEL);
 410         if (!new)
 411                 return -ENOMEM;
 412
 413         if (__memcg_init_list_lru_node(new, old_size, new_size)) {
 414                 kvfree(new);
 415                 return -ENOMEM;
 416         }
 417
 418         memcpy(&new->lru, &old->lru, old_size * sizeof(void *));
 419
 420         /*
 421          * The locking below allows readers that hold nlru->lock avoid taking
 422          * rcu_read_lock (see list_lru_from_memcg_idx).
 423          *
 424          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
 425          * we have to use IRQ-safe primitives here to avoid deadlock.
 426          */
 427         spin_lock_irq(&nlru->lock);
 428         rcu_assign_pointer(nlru->memcg_lrus, new);
 429         spin_unlock_irq(&nlru->lock);
 430
 431         call_rcu(&old->rcu, kvfree_rcu);
 432         return 0;
 433 }
 434
 435 static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru,
 436                                               int old_size, int new_size)
 437 {
 438         struct list_lru_memcg *memcg_lrus;
 439
 440         memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus,
 441                                                lockdep_is_held(&list_lrus_mutex));
 442         /* do not bother shrinking the array back to the old size, because we
 443          * cannot handle allocation failures here */
 444         __memcg_destroy_list_lru_node(memcg_lrus, old_size, new_size);
 445 }
 446
 447 static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
 448 {
 449         int i;
 450
 451         lru->memcg_aware = memcg_aware;
 452
 453         if (!memcg_aware)
 454                 return 0;
 455
 456         for_each_node(i) {
 457                 if (memcg_init_list_lru_node(&lru->node[i]))
 458                         goto fail;
 459         }
 460         return 0;
 461 fail:
 462         for (i = i - 1; i >= 0; i--) {
 463                 if (!lru->node[i].memcg_lrus)
 464                         continue;
 465                 memcg_destroy_list_lru_node(&lru->node[i]);
 466         }
 467         return -ENOMEM;
 468 }
 469
 470 static void memcg_destroy_list_lru(struct list_lru *lru)
 471 {
 472         int i;
 473
 474         if (!list_lru_memcg_aware(lru))
 475                 return;
 476
 477         for_each_node(i)
 478                 memcg_destroy_list_lru_node(&lru->node[i]);
 479 }
 480
 481 static int memcg_update_list_lru(struct list_lru *lru,
 482                                  int old_size, int new_size)
 483 {
 484         int i;
 485
 486         if (!list_lru_memcg_aware(lru))
 487                 return 0;
 488
 489         for_each_node(i) {
 490                 if (memcg_update_list_lru_node(&lru->node[i],
 491                                                old_size, new_size))
 492                         goto fail;
 493         }
 494         return 0;
 495 fail:
 496         for (i = i - 1; i >= 0; i--) {
 497                 if (!lru->node[i].memcg_lrus)
 498                         continue;
 499
 500                 memcg_cancel_update_list_lru_node(&lru->node[i],
 501                                                   old_size, new_size);
 502         }
 503         return -ENOMEM;
 504 }
 505
 506 static void memcg_cancel_update_list_lru(struct list_lru *lru,
 507                                          int old_size, int new_size)
 508 {
 509         int i;
 510
 511         if (!list_lru_memcg_aware(lru))
 512                 return;
 513
 514         for_each_node(i)
 515                 memcg_cancel_update_list_lru_node(&lru->node[i],
 516                                                   old_size, new_size);
 517 }
 518
 519 int memcg_update_all_list_lrus(int new_size)
 520 {
 521         int ret = 0;
 522         struct list_lru *lru;
 523         int old_size = memcg_nr_cache_ids;
 524
 525         mutex_lock(&list_lrus_mutex);
 526         list_for_each_entry(lru, &list_lrus, list) {
 527                 ret = memcg_update_list_lru(lru, old_size, new_size);
 528                 if (ret)
 529                         goto fail;
 530         }
 531 out:
 532         mutex_unlock(&list_lrus_mutex);
 533         return ret;
 534 fail:
 535         list_for_each_entry_continue_reverse(lru, &list_lrus, list)
 536                 memcg_cancel_update_list_lru(lru, old_size, new_size);
 537         goto out;
 538 }
 539
 540 static void memcg_drain_list_lru_node(struct list_lru *lru, int nid,
 541                                       int src_idx, struct mem_cgroup *dst_memcg)
 542 {
 543         struct list_lru_node *nlru = &lru->node[nid];
 544         int dst_idx = dst_memcg->kmemcg_id;
 545         struct list_lru_one *src, *dst;
 546         bool set;
 547
 548         /*
 549          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
 550          * we have to use IRQ-safe primitives here to avoid deadlock.
 551          */
 552         spin_lock_irq(&nlru->lock);
 553
 554         src = list_lru_from_memcg_idx(nlru, src_idx);
 555         dst = list_lru_from_memcg_idx(nlru, dst_idx);
 556
 557         list_splice_init(&src->list, &dst->list);
 558         set = (!dst->nr_items && src->nr_items);
 559         dst->nr_items += src->nr_items;
 560         if (set)
 561                 memcg_set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
 562         src->nr_items = 0;
 563
 564         spin_unlock_irq(&nlru->lock);
 565 }
 566
 567 static void memcg_drain_list_lru(struct list_lru *lru,
 568                                  int src_idx, struct mem_cgroup *dst_memcg)
 569 {
 570         int i;
 571
 572         if (!list_lru_memcg_aware(lru))
 573                 return;
 574
 575         for_each_node(i)
 576                 memcg_drain_list_lru_node(lru, i, src_idx, dst_memcg);
 577 }
 578
 579 void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg)
 580 {
 581         struct list_lru *lru;
 582
 583         mutex_lock(&list_lrus_mutex);
 584         list_for_each_entry(lru, &list_lrus, list)
 585                 memcg_drain_list_lru(lru, src_idx, dst_memcg);
 586         mutex_unlock(&list_lrus_mutex);
 587 }
 588 #else
 589 static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
 590 {
 591         return 0;
 592 }
 593
 594 static void memcg_destroy_list_lru(struct list_lru *lru)
 595 {
 596 }
 597 #endif /* CONFIG_MEMCG_KMEM */
 598
 599 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
 600                     struct lock_class_key *key, struct shrinker *shrinker)
 601 {
 602         int i;
 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 = kcalloc(nr_node_ids, sizeof(*lru->node), 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);