1 /* 2 * Slab allocator functions that are independent of the allocator strategy 3 * 4 * (C) 2012 Christoph Lameter <cl@linux.com> 5 */ 6 #include <linux/slab.h> 7 8 #include <linux/mm.h> 9 #include <linux/poison.h> 10 #include <linux/interrupt.h> 11 #include <linux/memory.h> 12 #include <linux/compiler.h> 13 #include <linux/module.h> 14 #include <linux/cpu.h> 15 #include <linux/uaccess.h> 16 #include <linux/seq_file.h> 17 #include <linux/proc_fs.h> 18 #include <asm/cacheflush.h> 19 #include <asm/tlbflush.h> 20 #include <asm/page.h> 21 #include <linux/memcontrol.h> 22 23 #define CREATE_TRACE_POINTS 24 #include <trace/events/kmem.h> 25 26 #include "slab.h" 27 28 enum slab_state slab_state; 29 LIST_HEAD(slab_caches); 30 DEFINE_MUTEX(slab_mutex); 31 struct kmem_cache *kmem_cache; 32 33 /* 34 * Set of flags that will prevent slab merging 35 */ 36 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 37 SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \ 38 SLAB_FAILSLAB | SLAB_KASAN) 39 40 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 41 SLAB_NOTRACK | SLAB_ACCOUNT) 42 43 /* 44 * Merge control. If this is set then no merging of slab caches will occur. 45 * (Could be removed. This was introduced to pacify the merge skeptics.) 46 */ 47 static int slab_nomerge; 48 49 static int __init setup_slab_nomerge(char *str) 50 { 51 slab_nomerge = 1; 52 return 1; 53 } 54 55 #ifdef CONFIG_SLUB 56 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 57 #endif 58 59 __setup("slab_nomerge", setup_slab_nomerge); 60 61 /* 62 * Determine the size of a slab object 63 */ 64 unsigned int kmem_cache_size(struct kmem_cache *s) 65 { 66 return s->object_size; 67 } 68 EXPORT_SYMBOL(kmem_cache_size); 69 70 #ifdef CONFIG_DEBUG_VM 71 static int kmem_cache_sanity_check(const char *name, size_t size) 72 { 73 struct kmem_cache *s = NULL; 74 75 if (!name || in_interrupt() || size < sizeof(void *) || 76 size > KMALLOC_MAX_SIZE) { 77 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 78 return -EINVAL; 79 } 80 81 list_for_each_entry(s, &slab_caches, list) { 82 char tmp; 83 int res; 84 85 /* 86 * This happens when the module gets unloaded and doesn't 87 * destroy its slab cache and no-one else reuses the vmalloc 88 * area of the module. Print a warning. 89 */ 90 res = probe_kernel_address(s->name, tmp); 91 if (res) { 92 pr_err("Slab cache with size %d has lost its name\n", 93 s->object_size); 94 continue; 95 } 96 } 97 98 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 99 return 0; 100 } 101 #else 102 static inline int kmem_cache_sanity_check(const char *name, size_t size) 103 { 104 return 0; 105 } 106 #endif 107 108 void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p) 109 { 110 size_t i; 111 112 for (i = 0; i < nr; i++) { 113 if (s) 114 kmem_cache_free(s, p[i]); 115 else 116 kfree(p[i]); 117 } 118 } 119 120 int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, 121 void **p) 122 { 123 size_t i; 124 125 for (i = 0; i < nr; i++) { 126 void *x = p[i] = kmem_cache_alloc(s, flags); 127 if (!x) { 128 __kmem_cache_free_bulk(s, i, p); 129 return 0; 130 } 131 } 132 return i; 133 } 134 135 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) 136 void slab_init_memcg_params(struct kmem_cache *s) 137 { 138 s->memcg_params.is_root_cache = true; 139 INIT_LIST_HEAD(&s->memcg_params.list); 140 RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL); 141 } 142 143 static int init_memcg_params(struct kmem_cache *s, 144 struct mem_cgroup *memcg, struct kmem_cache *root_cache) 145 { 146 struct memcg_cache_array *arr; 147 148 if (memcg) { 149 s->memcg_params.is_root_cache = false; 150 s->memcg_params.memcg = memcg; 151 s->memcg_params.root_cache = root_cache; 152 return 0; 153 } 154 155 slab_init_memcg_params(s); 156 157 if (!memcg_nr_cache_ids) 158 return 0; 159 160 arr = kzalloc(sizeof(struct memcg_cache_array) + 161 memcg_nr_cache_ids * sizeof(void *), 162 GFP_KERNEL); 163 if (!arr) 164 return -ENOMEM; 165 166 RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr); 167 return 0; 168 } 169 170 static void destroy_memcg_params(struct kmem_cache *s) 171 { 172 if (is_root_cache(s)) 173 kfree(rcu_access_pointer(s->memcg_params.memcg_caches)); 174 } 175 176 static int update_memcg_params(struct kmem_cache *s, int new_array_size) 177 { 178 struct memcg_cache_array *old, *new; 179 180 if (!is_root_cache(s)) 181 return 0; 182 183 new = kzalloc(sizeof(struct memcg_cache_array) + 184 new_array_size * sizeof(void *), GFP_KERNEL); 185 if (!new) 186 return -ENOMEM; 187 188 old = rcu_dereference_protected(s->memcg_params.memcg_caches, 189 lockdep_is_held(&slab_mutex)); 190 if (old) 191 memcpy(new->entries, old->entries, 192 memcg_nr_cache_ids * sizeof(void *)); 193 194 rcu_assign_pointer(s->memcg_params.memcg_caches, new); 195 if (old) 196 kfree_rcu(old, rcu); 197 return 0; 198 } 199 200 int memcg_update_all_caches(int num_memcgs) 201 { 202 struct kmem_cache *s; 203 int ret = 0; 204 205 mutex_lock(&slab_mutex); 206 list_for_each_entry(s, &slab_caches, list) { 207 ret = update_memcg_params(s, num_memcgs); 208 /* 209 * Instead of freeing the memory, we'll just leave the caches 210 * up to this point in an updated state. 211 */ 212 if (ret) 213 break; 214 } 215 mutex_unlock(&slab_mutex); 216 return ret; 217 } 218 #else 219 static inline int init_memcg_params(struct kmem_cache *s, 220 struct mem_cgroup *memcg, struct kmem_cache *root_cache) 221 { 222 return 0; 223 } 224 225 static inline void destroy_memcg_params(struct kmem_cache *s) 226 { 227 } 228 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */ 229 230 /* 231 * Find a mergeable slab cache 232 */ 233 int slab_unmergeable(struct kmem_cache *s) 234 { 235 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 236 return 1; 237 238 if (!is_root_cache(s)) 239 return 1; 240 241 if (s->ctor) 242 return 1; 243 244 /* 245 * We may have set a slab to be unmergeable during bootstrap. 246 */ 247 if (s->refcount < 0) 248 return 1; 249 250 return 0; 251 } 252 253 struct kmem_cache *find_mergeable(size_t size, size_t align, 254 unsigned long flags, const char *name, void (*ctor)(void *)) 255 { 256 struct kmem_cache *s; 257 258 if (slab_nomerge || (flags & SLAB_NEVER_MERGE)) 259 return NULL; 260 261 if (ctor) 262 return NULL; 263 264 size = ALIGN(size, sizeof(void *)); 265 align = calculate_alignment(flags, align, size); 266 size = ALIGN(size, align); 267 flags = kmem_cache_flags(size, flags, name, NULL); 268 269 list_for_each_entry_reverse(s, &slab_caches, list) { 270 if (slab_unmergeable(s)) 271 continue; 272 273 if (size > s->size) 274 continue; 275 276 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 277 continue; 278 /* 279 * Check if alignment is compatible. 280 * Courtesy of Adrian Drzewiecki 281 */ 282 if ((s->size & ~(align - 1)) != s->size) 283 continue; 284 285 if (s->size - size >= sizeof(void *)) 286 continue; 287 288 if (IS_ENABLED(CONFIG_SLAB) && align && 289 (align > s->align || s->align % align)) 290 continue; 291 292 return s; 293 } 294 return NULL; 295 } 296 297 /* 298 * Figure out what the alignment of the objects will be given a set of 299 * flags, a user specified alignment and the size of the objects. 300 */ 301 unsigned long calculate_alignment(unsigned long flags, 302 unsigned long align, unsigned long size) 303 { 304 /* 305 * If the user wants hardware cache aligned objects then follow that 306 * suggestion if the object is sufficiently large. 307 * 308 * The hardware cache alignment cannot override the specified 309 * alignment though. If that is greater then use it. 310 */ 311 if (flags & SLAB_HWCACHE_ALIGN) { 312 unsigned long ralign = cache_line_size(); 313 while (size <= ralign / 2) 314 ralign /= 2; 315 align = max(align, ralign); 316 } 317 318 if (align < ARCH_SLAB_MINALIGN) 319 align = ARCH_SLAB_MINALIGN; 320 321 return ALIGN(align, sizeof(void *)); 322 } 323 324 static struct kmem_cache *create_cache(const char *name, 325 size_t object_size, size_t size, size_t align, 326 unsigned long flags, void (*ctor)(void *), 327 struct mem_cgroup *memcg, struct kmem_cache *root_cache) 328 { 329 struct kmem_cache *s; 330 int err; 331 332 err = -ENOMEM; 333 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 334 if (!s) 335 goto out; 336 337 s->name = name; 338 s->object_size = object_size; 339 s->size = size; 340 s->align = align; 341 s->ctor = ctor; 342 343 err = init_memcg_params(s, memcg, root_cache); 344 if (err) 345 goto out_free_cache; 346 347 err = __kmem_cache_create(s, flags); 348 if (err) 349 goto out_free_cache; 350 351 s->refcount = 1; 352 list_add(&s->list, &slab_caches); 353 out: 354 if (err) 355 return ERR_PTR(err); 356 return s; 357 358 out_free_cache: 359 destroy_memcg_params(s); 360 kmem_cache_free(kmem_cache, s); 361 goto out; 362 } 363 364 /* 365 * kmem_cache_create - Create a cache. 366 * @name: A string which is used in /proc/slabinfo to identify this cache. 367 * @size: The size of objects to be created in this cache. 368 * @align: The required alignment for the objects. 369 * @flags: SLAB flags 370 * @ctor: A constructor for the objects. 371 * 372 * Returns a ptr to the cache on success, NULL on failure. 373 * Cannot be called within a interrupt, but can be interrupted. 374 * The @ctor is run when new pages are allocated by the cache. 375 * 376 * The flags are 377 * 378 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 379 * to catch references to uninitialised memory. 380 * 381 * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check 382 * for buffer overruns. 383 * 384 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 385 * cacheline. This can be beneficial if you're counting cycles as closely 386 * as davem. 387 */ 388 struct kmem_cache * 389 kmem_cache_create(const char *name, size_t size, size_t align, 390 unsigned long flags, void (*ctor)(void *)) 391 { 392 struct kmem_cache *s = NULL; 393 const char *cache_name; 394 int err; 395 396 get_online_cpus(); 397 get_online_mems(); 398 memcg_get_cache_ids(); 399 400 mutex_lock(&slab_mutex); 401 402 err = kmem_cache_sanity_check(name, size); 403 if (err) { 404 goto out_unlock; 405 } 406 407 /* Refuse requests with allocator specific flags */ 408 if (flags & ~SLAB_FLAGS_PERMITTED) { 409 err = -EINVAL; 410 goto out_unlock; 411 } 412 413 /* 414 * Some allocators will constraint the set of valid flags to a subset 415 * of all flags. We expect them to define CACHE_CREATE_MASK in this 416 * case, and we'll just provide them with a sanitized version of the 417 * passed flags. 418 */ 419 flags &= CACHE_CREATE_MASK; 420 421 s = __kmem_cache_alias(name, size, align, flags, ctor); 422 if (s) 423 goto out_unlock; 424 425 cache_name = kstrdup_const(name, GFP_KERNEL); 426 if (!cache_name) { 427 err = -ENOMEM; 428 goto out_unlock; 429 } 430 431 s = create_cache(cache_name, size, size, 432 calculate_alignment(flags, align, size), 433 flags, ctor, NULL, NULL); 434 if (IS_ERR(s)) { 435 err = PTR_ERR(s); 436 kfree_const(cache_name); 437 } 438 439 out_unlock: 440 mutex_unlock(&slab_mutex); 441 442 memcg_put_cache_ids(); 443 put_online_mems(); 444 put_online_cpus(); 445 446 if (err) { 447 if (flags & SLAB_PANIC) 448 panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n", 449 name, err); 450 else { 451 pr_warn("kmem_cache_create(%s) failed with error %d\n", 452 name, err); 453 dump_stack(); 454 } 455 return NULL; 456 } 457 return s; 458 } 459 EXPORT_SYMBOL(kmem_cache_create); 460 461 static int shutdown_cache(struct kmem_cache *s, 462 struct list_head *release, bool *need_rcu_barrier) 463 { 464 if (__kmem_cache_shutdown(s) != 0) 465 return -EBUSY; 466 467 if (s->flags & SLAB_DESTROY_BY_RCU) 468 *need_rcu_barrier = true; 469 470 list_move(&s->list, release); 471 return 0; 472 } 473 474 static void release_caches(struct list_head *release, bool need_rcu_barrier) 475 { 476 struct kmem_cache *s, *s2; 477 478 if (need_rcu_barrier) 479 rcu_barrier(); 480 481 list_for_each_entry_safe(s, s2, release, list) { 482 #ifdef SLAB_SUPPORTS_SYSFS 483 sysfs_slab_remove(s); 484 #else 485 slab_kmem_cache_release(s); 486 #endif 487 } 488 } 489 490 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) 491 /* 492 * memcg_create_kmem_cache - Create a cache for a memory cgroup. 493 * @memcg: The memory cgroup the new cache is for. 494 * @root_cache: The parent of the new cache. 495 * 496 * This function attempts to create a kmem cache that will serve allocation 497 * requests going from @memcg to @root_cache. The new cache inherits properties 498 * from its parent. 499 */ 500 void memcg_create_kmem_cache(struct mem_cgroup *memcg, 501 struct kmem_cache *root_cache) 502 { 503 static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */ 504 struct cgroup_subsys_state *css = &memcg->css; 505 struct memcg_cache_array *arr; 506 struct kmem_cache *s = NULL; 507 char *cache_name; 508 int idx; 509 510 get_online_cpus(); 511 get_online_mems(); 512 513 mutex_lock(&slab_mutex); 514 515 /* 516 * The memory cgroup could have been offlined while the cache 517 * creation work was pending. 518 */ 519 if (memcg->kmem_state != KMEM_ONLINE) 520 goto out_unlock; 521 522 idx = memcg_cache_id(memcg); 523 arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches, 524 lockdep_is_held(&slab_mutex)); 525 526 /* 527 * Since per-memcg caches are created asynchronously on first 528 * allocation (see memcg_kmem_get_cache()), several threads can try to 529 * create the same cache, but only one of them may succeed. 530 */ 531 if (arr->entries[idx]) 532 goto out_unlock; 533 534 cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf)); 535 cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name, 536 css->serial_nr, memcg_name_buf); 537 if (!cache_name) 538 goto out_unlock; 539 540 s = create_cache(cache_name, root_cache->object_size, 541 root_cache->size, root_cache->align, 542 root_cache->flags & CACHE_CREATE_MASK, 543 root_cache->ctor, memcg, root_cache); 544 /* 545 * If we could not create a memcg cache, do not complain, because 546 * that's not critical at all as we can always proceed with the root 547 * cache. 548 */ 549 if (IS_ERR(s)) { 550 kfree(cache_name); 551 goto out_unlock; 552 } 553 554 list_add(&s->memcg_params.list, &root_cache->memcg_params.list); 555 556 /* 557 * Since readers won't lock (see cache_from_memcg_idx()), we need a 558 * barrier here to ensure nobody will see the kmem_cache partially 559 * initialized. 560 */ 561 smp_wmb(); 562 arr->entries[idx] = s; 563 564 out_unlock: 565 mutex_unlock(&slab_mutex); 566 567 put_online_mems(); 568 put_online_cpus(); 569 } 570 571 void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg) 572 { 573 int idx; 574 struct memcg_cache_array *arr; 575 struct kmem_cache *s, *c; 576 577 idx = memcg_cache_id(memcg); 578 579 get_online_cpus(); 580 get_online_mems(); 581 582 #ifdef CONFIG_SLUB 583 /* 584 * In case of SLUB, we need to disable empty slab caching to 585 * avoid pinning the offline memory cgroup by freeable kmem 586 * pages charged to it. SLAB doesn't need this, as it 587 * periodically purges unused slabs. 588 */ 589 mutex_lock(&slab_mutex); 590 list_for_each_entry(s, &slab_caches, list) { 591 c = is_root_cache(s) ? cache_from_memcg_idx(s, idx) : NULL; 592 if (c) { 593 c->cpu_partial = 0; 594 c->min_partial = 0; 595 } 596 } 597 mutex_unlock(&slab_mutex); 598 /* 599 * kmem_cache->cpu_partial is checked locklessly (see 600 * put_cpu_partial()). Make sure the change is visible. 601 */ 602 synchronize_sched(); 603 #endif 604 605 mutex_lock(&slab_mutex); 606 list_for_each_entry(s, &slab_caches, list) { 607 if (!is_root_cache(s)) 608 continue; 609 610 arr = rcu_dereference_protected(s->memcg_params.memcg_caches, 611 lockdep_is_held(&slab_mutex)); 612 c = arr->entries[idx]; 613 if (!c) 614 continue; 615 616 __kmem_cache_shrink(c); 617 arr->entries[idx] = NULL; 618 } 619 mutex_unlock(&slab_mutex); 620 621 put_online_mems(); 622 put_online_cpus(); 623 } 624 625 static int __shutdown_memcg_cache(struct kmem_cache *s, 626 struct list_head *release, bool *need_rcu_barrier) 627 { 628 BUG_ON(is_root_cache(s)); 629 630 if (shutdown_cache(s, release, need_rcu_barrier)) 631 return -EBUSY; 632 633 list_del(&s->memcg_params.list); 634 return 0; 635 } 636 637 void memcg_destroy_kmem_caches(struct mem_cgroup *memcg) 638 { 639 LIST_HEAD(release); 640 bool need_rcu_barrier = false; 641 struct kmem_cache *s, *s2; 642 643 get_online_cpus(); 644 get_online_mems(); 645 646 mutex_lock(&slab_mutex); 647 list_for_each_entry_safe(s, s2, &slab_caches, list) { 648 if (is_root_cache(s) || s->memcg_params.memcg != memcg) 649 continue; 650 /* 651 * The cgroup is about to be freed and therefore has no charges 652 * left. Hence, all its caches must be empty by now. 653 */ 654 BUG_ON(__shutdown_memcg_cache(s, &release, &need_rcu_barrier)); 655 } 656 mutex_unlock(&slab_mutex); 657 658 put_online_mems(); 659 put_online_cpus(); 660 661 release_caches(&release, need_rcu_barrier); 662 } 663 664 static int shutdown_memcg_caches(struct kmem_cache *s, 665 struct list_head *release, bool *need_rcu_barrier) 666 { 667 struct memcg_cache_array *arr; 668 struct kmem_cache *c, *c2; 669 LIST_HEAD(busy); 670 int i; 671 672 BUG_ON(!is_root_cache(s)); 673 674 /* 675 * First, shutdown active caches, i.e. caches that belong to online 676 * memory cgroups. 677 */ 678 arr = rcu_dereference_protected(s->memcg_params.memcg_caches, 679 lockdep_is_held(&slab_mutex)); 680 for_each_memcg_cache_index(i) { 681 c = arr->entries[i]; 682 if (!c) 683 continue; 684 if (__shutdown_memcg_cache(c, release, need_rcu_barrier)) 685 /* 686 * The cache still has objects. Move it to a temporary 687 * list so as not to try to destroy it for a second 688 * time while iterating over inactive caches below. 689 */ 690 list_move(&c->memcg_params.list, &busy); 691 else 692 /* 693 * The cache is empty and will be destroyed soon. Clear 694 * the pointer to it in the memcg_caches array so that 695 * it will never be accessed even if the root cache 696 * stays alive. 697 */ 698 arr->entries[i] = NULL; 699 } 700 701 /* 702 * Second, shutdown all caches left from memory cgroups that are now 703 * offline. 704 */ 705 list_for_each_entry_safe(c, c2, &s->memcg_params.list, 706 memcg_params.list) 707 __shutdown_memcg_cache(c, release, need_rcu_barrier); 708 709 list_splice(&busy, &s->memcg_params.list); 710 711 /* 712 * A cache being destroyed must be empty. In particular, this means 713 * that all per memcg caches attached to it must be empty too. 714 */ 715 if (!list_empty(&s->memcg_params.list)) 716 return -EBUSY; 717 return 0; 718 } 719 #else 720 static inline int shutdown_memcg_caches(struct kmem_cache *s, 721 struct list_head *release, bool *need_rcu_barrier) 722 { 723 return 0; 724 } 725 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */ 726 727 void slab_kmem_cache_release(struct kmem_cache *s) 728 { 729 __kmem_cache_release(s); 730 destroy_memcg_params(s); 731 kfree_const(s->name); 732 kmem_cache_free(kmem_cache, s); 733 } 734 735 void kmem_cache_destroy(struct kmem_cache *s) 736 { 737 LIST_HEAD(release); 738 bool need_rcu_barrier = false; 739 int err; 740 741 if (unlikely(!s)) 742 return; 743 744 get_online_cpus(); 745 get_online_mems(); 746 747 kasan_cache_destroy(s); 748 mutex_lock(&slab_mutex); 749 750 s->refcount--; 751 if (s->refcount) 752 goto out_unlock; 753 754 err = shutdown_memcg_caches(s, &release, &need_rcu_barrier); 755 if (!err) 756 err = shutdown_cache(s, &release, &need_rcu_barrier); 757 758 if (err) { 759 pr_err("kmem_cache_destroy %s: Slab cache still has objects\n", 760 s->name); 761 dump_stack(); 762 } 763 out_unlock: 764 mutex_unlock(&slab_mutex); 765 766 put_online_mems(); 767 put_online_cpus(); 768 769 release_caches(&release, need_rcu_barrier); 770 } 771 EXPORT_SYMBOL(kmem_cache_destroy); 772 773 /** 774 * kmem_cache_shrink - Shrink a cache. 775 * @cachep: The cache to shrink. 776 * 777 * Releases as many slabs as possible for a cache. 778 * To help debugging, a zero exit status indicates all slabs were released. 779 */ 780 int kmem_cache_shrink(struct kmem_cache *cachep) 781 { 782 int ret; 783 784 get_online_cpus(); 785 get_online_mems(); 786 kasan_cache_shrink(cachep); 787 ret = __kmem_cache_shrink(cachep); 788 put_online_mems(); 789 put_online_cpus(); 790 return ret; 791 } 792 EXPORT_SYMBOL(kmem_cache_shrink); 793 794 bool slab_is_available(void) 795 { 796 return slab_state >= UP; 797 } 798 799 #ifndef CONFIG_SLOB 800 /* Create a cache during boot when no slab services are available yet */ 801 void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size, 802 unsigned long flags) 803 { 804 int err; 805 806 s->name = name; 807 s->size = s->object_size = size; 808 s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size); 809 810 slab_init_memcg_params(s); 811 812 err = __kmem_cache_create(s, flags); 813 814 if (err) 815 panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n", 816 name, size, err); 817 818 s->refcount = -1; /* Exempt from merging for now */ 819 } 820 821 struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size, 822 unsigned long flags) 823 { 824 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 825 826 if (!s) 827 panic("Out of memory when creating slab %s\n", name); 828 829 create_boot_cache(s, name, size, flags); 830 list_add(&s->list, &slab_caches); 831 s->refcount = 1; 832 return s; 833 } 834 835 struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1]; 836 EXPORT_SYMBOL(kmalloc_caches); 837 838 #ifdef CONFIG_ZONE_DMA 839 struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1]; 840 EXPORT_SYMBOL(kmalloc_dma_caches); 841 #endif 842 843 /* 844 * Conversion table for small slabs sizes / 8 to the index in the 845 * kmalloc array. This is necessary for slabs < 192 since we have non power 846 * of two cache sizes there. The size of larger slabs can be determined using 847 * fls. 848 */ 849 static s8 size_index[24] = { 850 3, /* 8 */ 851 4, /* 16 */ 852 5, /* 24 */ 853 5, /* 32 */ 854 6, /* 40 */ 855 6, /* 48 */ 856 6, /* 56 */ 857 6, /* 64 */ 858 1, /* 72 */ 859 1, /* 80 */ 860 1, /* 88 */ 861 1, /* 96 */ 862 7, /* 104 */ 863 7, /* 112 */ 864 7, /* 120 */ 865 7, /* 128 */ 866 2, /* 136 */ 867 2, /* 144 */ 868 2, /* 152 */ 869 2, /* 160 */ 870 2, /* 168 */ 871 2, /* 176 */ 872 2, /* 184 */ 873 2 /* 192 */ 874 }; 875 876 static inline int size_index_elem(size_t bytes) 877 { 878 return (bytes - 1) / 8; 879 } 880 881 /* 882 * Find the kmem_cache structure that serves a given size of 883 * allocation 884 */ 885 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 886 { 887 int index; 888 889 if (unlikely(size > KMALLOC_MAX_SIZE)) { 890 WARN_ON_ONCE(!(flags & __GFP_NOWARN)); 891 return NULL; 892 } 893 894 if (size <= 192) { 895 if (!size) 896 return ZERO_SIZE_PTR; 897 898 index = size_index[size_index_elem(size)]; 899 } else 900 index = fls(size - 1); 901 902 #ifdef CONFIG_ZONE_DMA 903 if (unlikely((flags & GFP_DMA))) 904 return kmalloc_dma_caches[index]; 905 906 #endif 907 return kmalloc_caches[index]; 908 } 909 910 /* 911 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 912 * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is 913 * kmalloc-67108864. 914 */ 915 static struct { 916 const char *name; 917 unsigned long size; 918 } const kmalloc_info[] __initconst = { 919 {NULL, 0}, {"kmalloc-96", 96}, 920 {"kmalloc-192", 192}, {"kmalloc-8", 8}, 921 {"kmalloc-16", 16}, {"kmalloc-32", 32}, 922 {"kmalloc-64", 64}, {"kmalloc-128", 128}, 923 {"kmalloc-256", 256}, {"kmalloc-512", 512}, 924 {"kmalloc-1024", 1024}, {"kmalloc-2048", 2048}, 925 {"kmalloc-4096", 4096}, {"kmalloc-8192", 8192}, 926 {"kmalloc-16384", 16384}, {"kmalloc-32768", 32768}, 927 {"kmalloc-65536", 65536}, {"kmalloc-131072", 131072}, 928 {"kmalloc-262144", 262144}, {"kmalloc-524288", 524288}, 929 {"kmalloc-1048576", 1048576}, {"kmalloc-2097152", 2097152}, 930 {"kmalloc-4194304", 4194304}, {"kmalloc-8388608", 8388608}, 931 {"kmalloc-16777216", 16777216}, {"kmalloc-33554432", 33554432}, 932 {"kmalloc-67108864", 67108864} 933 }; 934 935 /* 936 * Patch up the size_index table if we have strange large alignment 937 * requirements for the kmalloc array. This is only the case for 938 * MIPS it seems. The standard arches will not generate any code here. 939 * 940 * Largest permitted alignment is 256 bytes due to the way we 941 * handle the index determination for the smaller caches. 942 * 943 * Make sure that nothing crazy happens if someone starts tinkering 944 * around with ARCH_KMALLOC_MINALIGN 945 */ 946 void __init setup_kmalloc_cache_index_table(void) 947 { 948 int i; 949 950 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 951 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); 952 953 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 954 int elem = size_index_elem(i); 955 956 if (elem >= ARRAY_SIZE(size_index)) 957 break; 958 size_index[elem] = KMALLOC_SHIFT_LOW; 959 } 960 961 if (KMALLOC_MIN_SIZE >= 64) { 962 /* 963 * The 96 byte size cache is not used if the alignment 964 * is 64 byte. 965 */ 966 for (i = 64 + 8; i <= 96; i += 8) 967 size_index[size_index_elem(i)] = 7; 968 969 } 970 971 if (KMALLOC_MIN_SIZE >= 128) { 972 /* 973 * The 192 byte sized cache is not used if the alignment 974 * is 128 byte. Redirect kmalloc to use the 256 byte cache 975 * instead. 976 */ 977 for (i = 128 + 8; i <= 192; i += 8) 978 size_index[size_index_elem(i)] = 8; 979 } 980 } 981 982 static void __init new_kmalloc_cache(int idx, unsigned long flags) 983 { 984 kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name, 985 kmalloc_info[idx].size, flags); 986 } 987 988 /* 989 * Create the kmalloc array. Some of the regular kmalloc arrays 990 * may already have been created because they were needed to 991 * enable allocations for slab creation. 992 */ 993 void __init create_kmalloc_caches(unsigned long flags) 994 { 995 int i; 996 997 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 998 if (!kmalloc_caches[i]) 999 new_kmalloc_cache(i, flags); 1000 1001 /* 1002 * Caches that are not of the two-to-the-power-of size. 1003 * These have to be created immediately after the 1004 * earlier power of two caches 1005 */ 1006 if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6) 1007 new_kmalloc_cache(1, flags); 1008 if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7) 1009 new_kmalloc_cache(2, flags); 1010 } 1011 1012 /* Kmalloc array is now usable */ 1013 slab_state = UP; 1014 1015 #ifdef CONFIG_ZONE_DMA 1016 for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { 1017 struct kmem_cache *s = kmalloc_caches[i]; 1018 1019 if (s) { 1020 int size = kmalloc_size(i); 1021 char *n = kasprintf(GFP_NOWAIT, 1022 "dma-kmalloc-%d", size); 1023 1024 BUG_ON(!n); 1025 kmalloc_dma_caches[i] = create_kmalloc_cache(n, 1026 size, SLAB_CACHE_DMA | flags); 1027 } 1028 } 1029 #endif 1030 } 1031 #endif /* !CONFIG_SLOB */ 1032 1033 /* 1034 * To avoid unnecessary overhead, we pass through large allocation requests 1035 * directly to the page allocator. We use __GFP_COMP, because we will need to 1036 * know the allocation order to free the pages properly in kfree. 1037 */ 1038 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 1039 { 1040 void *ret; 1041 struct page *page; 1042 1043 flags |= __GFP_COMP; 1044 page = alloc_pages(flags, order); 1045 ret = page ? page_address(page) : NULL; 1046 kmemleak_alloc(ret, size, 1, flags); 1047 kasan_kmalloc_large(ret, size, flags); 1048 return ret; 1049 } 1050 EXPORT_SYMBOL(kmalloc_order); 1051 1052 #ifdef CONFIG_TRACING 1053 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) 1054 { 1055 void *ret = kmalloc_order(size, flags, order); 1056 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags); 1057 return ret; 1058 } 1059 EXPORT_SYMBOL(kmalloc_order_trace); 1060 #endif 1061 1062 #ifdef CONFIG_SLAB_FREELIST_RANDOM 1063 /* Randomize a generic freelist */ 1064 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 1065 size_t count) 1066 { 1067 size_t i; 1068 unsigned int rand; 1069 1070 for (i = 0; i < count; i++) 1071 list[i] = i; 1072 1073 /* Fisher-Yates shuffle */ 1074 for (i = count - 1; i > 0; i--) { 1075 rand = prandom_u32_state(state); 1076 rand %= (i + 1); 1077 swap(list[i], list[rand]); 1078 } 1079 } 1080 1081 /* Create a random sequence per cache */ 1082 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 1083 gfp_t gfp) 1084 { 1085 struct rnd_state state; 1086 1087 if (count < 2 || cachep->random_seq) 1088 return 0; 1089 1090 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 1091 if (!cachep->random_seq) 1092 return -ENOMEM; 1093 1094 /* Get best entropy at this stage of boot */ 1095 prandom_seed_state(&state, get_random_long()); 1096 1097 freelist_randomize(&state, cachep->random_seq, count); 1098 return 0; 1099 } 1100 1101 /* Destroy the per-cache random freelist sequence */ 1102 void cache_random_seq_destroy(struct kmem_cache *cachep) 1103 { 1104 kfree(cachep->random_seq); 1105 cachep->random_seq = NULL; 1106 } 1107 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1108 1109 #ifdef CONFIG_SLABINFO 1110 1111 #ifdef CONFIG_SLAB 1112 #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR) 1113 #else 1114 #define SLABINFO_RIGHTS S_IRUSR 1115 #endif 1116 1117 static void print_slabinfo_header(struct seq_file *m) 1118 { 1119 /* 1120 * Output format version, so at least we can change it 1121 * without _too_ many complaints. 1122 */ 1123 #ifdef CONFIG_DEBUG_SLAB 1124 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 1125 #else 1126 seq_puts(m, "slabinfo - version: 2.1\n"); 1127 #endif 1128 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1129 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1130 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1131 #ifdef CONFIG_DEBUG_SLAB 1132 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 1133 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 1134 #endif 1135 seq_putc(m, '\n'); 1136 } 1137 1138 void *slab_start(struct seq_file *m, loff_t *pos) 1139 { 1140 mutex_lock(&slab_mutex); 1141 return seq_list_start(&slab_caches, *pos); 1142 } 1143 1144 void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1145 { 1146 return seq_list_next(p, &slab_caches, pos); 1147 } 1148 1149 void slab_stop(struct seq_file *m, void *p) 1150 { 1151 mutex_unlock(&slab_mutex); 1152 } 1153 1154 static void 1155 memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info) 1156 { 1157 struct kmem_cache *c; 1158 struct slabinfo sinfo; 1159 1160 if (!is_root_cache(s)) 1161 return; 1162 1163 for_each_memcg_cache(c, s) { 1164 memset(&sinfo, 0, sizeof(sinfo)); 1165 get_slabinfo(c, &sinfo); 1166 1167 info->active_slabs += sinfo.active_slabs; 1168 info->num_slabs += sinfo.num_slabs; 1169 info->shared_avail += sinfo.shared_avail; 1170 info->active_objs += sinfo.active_objs; 1171 info->num_objs += sinfo.num_objs; 1172 } 1173 } 1174 1175 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1176 { 1177 struct slabinfo sinfo; 1178 1179 memset(&sinfo, 0, sizeof(sinfo)); 1180 get_slabinfo(s, &sinfo); 1181 1182 memcg_accumulate_slabinfo(s, &sinfo); 1183 1184 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1185 cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size, 1186 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1187 1188 seq_printf(m, " : tunables %4u %4u %4u", 1189 sinfo.limit, sinfo.batchcount, sinfo.shared); 1190 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1191 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1192 slabinfo_show_stats(m, s); 1193 seq_putc(m, '\n'); 1194 } 1195 1196 static int slab_show(struct seq_file *m, void *p) 1197 { 1198 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1199 1200 if (p == slab_caches.next) 1201 print_slabinfo_header(m); 1202 if (is_root_cache(s)) 1203 cache_show(s, m); 1204 return 0; 1205 } 1206 1207 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) 1208 int memcg_slab_show(struct seq_file *m, void *p) 1209 { 1210 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1211 struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); 1212 1213 if (p == slab_caches.next) 1214 print_slabinfo_header(m); 1215 if (!is_root_cache(s) && s->memcg_params.memcg == memcg) 1216 cache_show(s, m); 1217 return 0; 1218 } 1219 #endif 1220 1221 /* 1222 * slabinfo_op - iterator that generates /proc/slabinfo 1223 * 1224 * Output layout: 1225 * cache-name 1226 * num-active-objs 1227 * total-objs 1228 * object size 1229 * num-active-slabs 1230 * total-slabs 1231 * num-pages-per-slab 1232 * + further values on SMP and with statistics enabled 1233 */ 1234 static const struct seq_operations slabinfo_op = { 1235 .start = slab_start, 1236 .next = slab_next, 1237 .stop = slab_stop, 1238 .show = slab_show, 1239 }; 1240 1241 static int slabinfo_open(struct inode *inode, struct file *file) 1242 { 1243 return seq_open(file, &slabinfo_op); 1244 } 1245 1246 static const struct file_operations proc_slabinfo_operations = { 1247 .open = slabinfo_open, 1248 .read = seq_read, 1249 .write = slabinfo_write, 1250 .llseek = seq_lseek, 1251 .release = seq_release, 1252 }; 1253 1254 static int __init slab_proc_init(void) 1255 { 1256 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, 1257 &proc_slabinfo_operations); 1258 return 0; 1259 } 1260 module_init(slab_proc_init); 1261 #endif /* CONFIG_SLABINFO */ 1262 1263 static __always_inline void *__do_krealloc(const void *p, size_t new_size, 1264 gfp_t flags) 1265 { 1266 void *ret; 1267 size_t ks = 0; 1268 1269 if (p) 1270 ks = ksize(p); 1271 1272 if (ks >= new_size) { 1273 kasan_krealloc((void *)p, new_size, flags); 1274 return (void *)p; 1275 } 1276 1277 ret = kmalloc_track_caller(new_size, flags); 1278 if (ret && p) 1279 memcpy(ret, p, ks); 1280 1281 return ret; 1282 } 1283 1284 /** 1285 * __krealloc - like krealloc() but don't free @p. 1286 * @p: object to reallocate memory for. 1287 * @new_size: how many bytes of memory are required. 1288 * @flags: the type of memory to allocate. 1289 * 1290 * This function is like krealloc() except it never frees the originally 1291 * allocated buffer. Use this if you don't want to free the buffer immediately 1292 * like, for example, with RCU. 1293 */ 1294 void *__krealloc(const void *p, size_t new_size, gfp_t flags) 1295 { 1296 if (unlikely(!new_size)) 1297 return ZERO_SIZE_PTR; 1298 1299 return __do_krealloc(p, new_size, flags); 1300 1301 } 1302 EXPORT_SYMBOL(__krealloc); 1303 1304 /** 1305 * krealloc - reallocate memory. The contents will remain unchanged. 1306 * @p: object to reallocate memory for. 1307 * @new_size: how many bytes of memory are required. 1308 * @flags: the type of memory to allocate. 1309 * 1310 * The contents of the object pointed to are preserved up to the 1311 * lesser of the new and old sizes. If @p is %NULL, krealloc() 1312 * behaves exactly like kmalloc(). If @new_size is 0 and @p is not a 1313 * %NULL pointer, the object pointed to is freed. 1314 */ 1315 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1316 { 1317 void *ret; 1318 1319 if (unlikely(!new_size)) { 1320 kfree(p); 1321 return ZERO_SIZE_PTR; 1322 } 1323 1324 ret = __do_krealloc(p, new_size, flags); 1325 if (ret && p != ret) 1326 kfree(p); 1327 1328 return ret; 1329 } 1330 EXPORT_SYMBOL(krealloc); 1331 1332 /** 1333 * kzfree - like kfree but zero memory 1334 * @p: object to free memory of 1335 * 1336 * The memory of the object @p points to is zeroed before freed. 1337 * If @p is %NULL, kzfree() does nothing. 1338 * 1339 * Note: this function zeroes the whole allocated buffer which can be a good 1340 * deal bigger than the requested buffer size passed to kmalloc(). So be 1341 * careful when using this function in performance sensitive code. 1342 */ 1343 void kzfree(const void *p) 1344 { 1345 size_t ks; 1346 void *mem = (void *)p; 1347 1348 if (unlikely(ZERO_OR_NULL_PTR(mem))) 1349 return; 1350 ks = ksize(mem); 1351 memset(mem, 0, ks); 1352 kfree(mem); 1353 } 1354 EXPORT_SYMBOL(kzfree); 1355 1356 /* Tracepoints definitions. */ 1357 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1358 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1359 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 1360 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 1361 EXPORT_TRACEPOINT_SYMBOL(kfree); 1362 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1363