1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Slab allocator functions that are independent of the allocator strategy 4 * 5 * (C) 2012 Christoph Lameter <cl@linux.com> 6 */ 7 #include <linux/slab.h> 8 9 #include <linux/mm.h> 10 #include <linux/poison.h> 11 #include <linux/interrupt.h> 12 #include <linux/memory.h> 13 #include <linux/cache.h> 14 #include <linux/compiler.h> 15 #include <linux/module.h> 16 #include <linux/cpu.h> 17 #include <linux/uaccess.h> 18 #include <linux/seq_file.h> 19 #include <linux/proc_fs.h> 20 #include <linux/debugfs.h> 21 #include <asm/cacheflush.h> 22 #include <asm/tlbflush.h> 23 #include <asm/page.h> 24 #include <linux/memcontrol.h> 25 26 #define CREATE_TRACE_POINTS 27 #include <trace/events/kmem.h> 28 29 #include "internal.h" 30 31 #include "slab.h" 32 33 enum slab_state slab_state; 34 LIST_HEAD(slab_caches); 35 DEFINE_MUTEX(slab_mutex); 36 struct kmem_cache *kmem_cache; 37 38 #ifdef CONFIG_HARDENED_USERCOPY 39 bool usercopy_fallback __ro_after_init = 40 IS_ENABLED(CONFIG_HARDENED_USERCOPY_FALLBACK); 41 module_param(usercopy_fallback, bool, 0400); 42 MODULE_PARM_DESC(usercopy_fallback, 43 "WARN instead of reject usercopy whitelist violations"); 44 #endif 45 46 static LIST_HEAD(slab_caches_to_rcu_destroy); 47 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 48 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 49 slab_caches_to_rcu_destroy_workfn); 50 51 /* 52 * Set of flags that will prevent slab merging 53 */ 54 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 55 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 56 SLAB_FAILSLAB | SLAB_KASAN) 57 58 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 59 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 60 61 /* 62 * Merge control. If this is set then no merging of slab caches will occur. 63 */ 64 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 65 66 static int __init setup_slab_nomerge(char *str) 67 { 68 slab_nomerge = true; 69 return 1; 70 } 71 72 #ifdef CONFIG_SLUB 73 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 74 #endif 75 76 __setup("slab_nomerge", setup_slab_nomerge); 77 78 /* 79 * Determine the size of a slab object 80 */ 81 unsigned int kmem_cache_size(struct kmem_cache *s) 82 { 83 return s->object_size; 84 } 85 EXPORT_SYMBOL(kmem_cache_size); 86 87 #ifdef CONFIG_DEBUG_VM 88 static int kmem_cache_sanity_check(const char *name, unsigned int size) 89 { 90 if (!name || in_interrupt() || size < sizeof(void *) || 91 size > KMALLOC_MAX_SIZE) { 92 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 93 return -EINVAL; 94 } 95 96 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 97 return 0; 98 } 99 #else 100 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 101 { 102 return 0; 103 } 104 #endif 105 106 void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p) 107 { 108 size_t i; 109 110 for (i = 0; i < nr; i++) { 111 if (s) 112 kmem_cache_free(s, p[i]); 113 else 114 kfree(p[i]); 115 } 116 } 117 118 int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, 119 void **p) 120 { 121 size_t i; 122 123 for (i = 0; i < nr; i++) { 124 void *x = p[i] = kmem_cache_alloc(s, flags); 125 if (!x) { 126 __kmem_cache_free_bulk(s, i, p); 127 return 0; 128 } 129 } 130 return i; 131 } 132 133 /* 134 * Figure out what the alignment of the objects will be given a set of 135 * flags, a user specified alignment and the size of the objects. 136 */ 137 static unsigned int calculate_alignment(slab_flags_t flags, 138 unsigned int align, unsigned int size) 139 { 140 /* 141 * If the user wants hardware cache aligned objects then follow that 142 * suggestion if the object is sufficiently large. 143 * 144 * The hardware cache alignment cannot override the specified 145 * alignment though. If that is greater then use it. 146 */ 147 if (flags & SLAB_HWCACHE_ALIGN) { 148 unsigned int ralign; 149 150 ralign = cache_line_size(); 151 while (size <= ralign / 2) 152 ralign /= 2; 153 align = max(align, ralign); 154 } 155 156 if (align < ARCH_SLAB_MINALIGN) 157 align = ARCH_SLAB_MINALIGN; 158 159 return ALIGN(align, sizeof(void *)); 160 } 161 162 /* 163 * Find a mergeable slab cache 164 */ 165 int slab_unmergeable(struct kmem_cache *s) 166 { 167 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 168 return 1; 169 170 if (s->ctor) 171 return 1; 172 173 if (s->usersize) 174 return 1; 175 176 /* 177 * We may have set a slab to be unmergeable during bootstrap. 178 */ 179 if (s->refcount < 0) 180 return 1; 181 182 return 0; 183 } 184 185 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 186 slab_flags_t flags, const char *name, void (*ctor)(void *)) 187 { 188 struct kmem_cache *s; 189 190 if (slab_nomerge) 191 return NULL; 192 193 if (ctor) 194 return NULL; 195 196 size = ALIGN(size, sizeof(void *)); 197 align = calculate_alignment(flags, align, size); 198 size = ALIGN(size, align); 199 flags = kmem_cache_flags(size, flags, name, NULL); 200 201 if (flags & SLAB_NEVER_MERGE) 202 return NULL; 203 204 list_for_each_entry_reverse(s, &slab_caches, list) { 205 if (slab_unmergeable(s)) 206 continue; 207 208 if (size > s->size) 209 continue; 210 211 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 212 continue; 213 /* 214 * Check if alignment is compatible. 215 * Courtesy of Adrian Drzewiecki 216 */ 217 if ((s->size & ~(align - 1)) != s->size) 218 continue; 219 220 if (s->size - size >= sizeof(void *)) 221 continue; 222 223 if (IS_ENABLED(CONFIG_SLAB) && align && 224 (align > s->align || s->align % align)) 225 continue; 226 227 return s; 228 } 229 return NULL; 230 } 231 232 static struct kmem_cache *create_cache(const char *name, 233 unsigned int object_size, unsigned int align, 234 slab_flags_t flags, unsigned int useroffset, 235 unsigned int usersize, void (*ctor)(void *), 236 struct kmem_cache *root_cache) 237 { 238 struct kmem_cache *s; 239 int err; 240 241 if (WARN_ON(useroffset + usersize > object_size)) 242 useroffset = usersize = 0; 243 244 err = -ENOMEM; 245 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 246 if (!s) 247 goto out; 248 249 s->name = name; 250 s->size = s->object_size = object_size; 251 s->align = align; 252 s->ctor = ctor; 253 s->useroffset = useroffset; 254 s->usersize = usersize; 255 256 err = __kmem_cache_create(s, flags); 257 if (err) 258 goto out_free_cache; 259 260 s->refcount = 1; 261 list_add(&s->list, &slab_caches); 262 out: 263 if (err) 264 return ERR_PTR(err); 265 return s; 266 267 out_free_cache: 268 kmem_cache_free(kmem_cache, s); 269 goto out; 270 } 271 272 /** 273 * kmem_cache_create_usercopy - Create a cache with a region suitable 274 * for copying to userspace 275 * @name: A string which is used in /proc/slabinfo to identify this cache. 276 * @size: The size of objects to be created in this cache. 277 * @align: The required alignment for the objects. 278 * @flags: SLAB flags 279 * @useroffset: Usercopy region offset 280 * @usersize: Usercopy region size 281 * @ctor: A constructor for the objects. 282 * 283 * Cannot be called within a interrupt, but can be interrupted. 284 * The @ctor is run when new pages are allocated by the cache. 285 * 286 * The flags are 287 * 288 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 289 * to catch references to uninitialised memory. 290 * 291 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 292 * for buffer overruns. 293 * 294 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 295 * cacheline. This can be beneficial if you're counting cycles as closely 296 * as davem. 297 * 298 * Return: a pointer to the cache on success, NULL on failure. 299 */ 300 struct kmem_cache * 301 kmem_cache_create_usercopy(const char *name, 302 unsigned int size, unsigned int align, 303 slab_flags_t flags, 304 unsigned int useroffset, unsigned int usersize, 305 void (*ctor)(void *)) 306 { 307 struct kmem_cache *s = NULL; 308 const char *cache_name; 309 int err; 310 311 get_online_cpus(); 312 get_online_mems(); 313 314 mutex_lock(&slab_mutex); 315 316 err = kmem_cache_sanity_check(name, size); 317 if (err) { 318 goto out_unlock; 319 } 320 321 /* Refuse requests with allocator specific flags */ 322 if (flags & ~SLAB_FLAGS_PERMITTED) { 323 err = -EINVAL; 324 goto out_unlock; 325 } 326 327 /* 328 * Some allocators will constraint the set of valid flags to a subset 329 * of all flags. We expect them to define CACHE_CREATE_MASK in this 330 * case, and we'll just provide them with a sanitized version of the 331 * passed flags. 332 */ 333 flags &= CACHE_CREATE_MASK; 334 335 /* Fail closed on bad usersize of useroffset values. */ 336 if (WARN_ON(!usersize && useroffset) || 337 WARN_ON(size < usersize || size - usersize < useroffset)) 338 usersize = useroffset = 0; 339 340 if (!usersize) 341 s = __kmem_cache_alias(name, size, align, flags, ctor); 342 if (s) 343 goto out_unlock; 344 345 cache_name = kstrdup_const(name, GFP_KERNEL); 346 if (!cache_name) { 347 err = -ENOMEM; 348 goto out_unlock; 349 } 350 351 s = create_cache(cache_name, size, 352 calculate_alignment(flags, align, size), 353 flags, useroffset, usersize, ctor, NULL); 354 if (IS_ERR(s)) { 355 err = PTR_ERR(s); 356 kfree_const(cache_name); 357 } 358 359 out_unlock: 360 mutex_unlock(&slab_mutex); 361 362 put_online_mems(); 363 put_online_cpus(); 364 365 if (err) { 366 if (flags & SLAB_PANIC) 367 panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n", 368 name, err); 369 else { 370 pr_warn("kmem_cache_create(%s) failed with error %d\n", 371 name, err); 372 dump_stack(); 373 } 374 return NULL; 375 } 376 return s; 377 } 378 EXPORT_SYMBOL(kmem_cache_create_usercopy); 379 380 /** 381 * kmem_cache_create - Create a cache. 382 * @name: A string which is used in /proc/slabinfo to identify this cache. 383 * @size: The size of objects to be created in this cache. 384 * @align: The required alignment for the objects. 385 * @flags: SLAB flags 386 * @ctor: A constructor for the objects. 387 * 388 * Cannot be called within a interrupt, but can be interrupted. 389 * The @ctor is run when new pages are allocated by the cache. 390 * 391 * The flags are 392 * 393 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 394 * to catch references to uninitialised memory. 395 * 396 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 397 * for buffer overruns. 398 * 399 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 400 * cacheline. This can be beneficial if you're counting cycles as closely 401 * as davem. 402 * 403 * Return: a pointer to the cache on success, NULL on failure. 404 */ 405 struct kmem_cache * 406 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 407 slab_flags_t flags, void (*ctor)(void *)) 408 { 409 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 410 ctor); 411 } 412 EXPORT_SYMBOL(kmem_cache_create); 413 414 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 415 { 416 LIST_HEAD(to_destroy); 417 struct kmem_cache *s, *s2; 418 419 /* 420 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 421 * @slab_caches_to_rcu_destroy list. The slab pages are freed 422 * through RCU and the associated kmem_cache are dereferenced 423 * while freeing the pages, so the kmem_caches should be freed only 424 * after the pending RCU operations are finished. As rcu_barrier() 425 * is a pretty slow operation, we batch all pending destructions 426 * asynchronously. 427 */ 428 mutex_lock(&slab_mutex); 429 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 430 mutex_unlock(&slab_mutex); 431 432 if (list_empty(&to_destroy)) 433 return; 434 435 rcu_barrier(); 436 437 list_for_each_entry_safe(s, s2, &to_destroy, list) { 438 #ifdef SLAB_SUPPORTS_SYSFS 439 sysfs_slab_release(s); 440 #else 441 slab_kmem_cache_release(s); 442 #endif 443 } 444 } 445 446 static int shutdown_cache(struct kmem_cache *s) 447 { 448 /* free asan quarantined objects */ 449 kasan_cache_shutdown(s); 450 451 if (__kmem_cache_shutdown(s) != 0) 452 return -EBUSY; 453 454 list_del(&s->list); 455 456 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 457 #ifdef SLAB_SUPPORTS_SYSFS 458 sysfs_slab_unlink(s); 459 #endif 460 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 461 schedule_work(&slab_caches_to_rcu_destroy_work); 462 } else { 463 #ifdef SLAB_SUPPORTS_SYSFS 464 sysfs_slab_unlink(s); 465 sysfs_slab_release(s); 466 #else 467 slab_kmem_cache_release(s); 468 #endif 469 } 470 471 return 0; 472 } 473 474 void slab_kmem_cache_release(struct kmem_cache *s) 475 { 476 __kmem_cache_release(s); 477 kfree_const(s->name); 478 kmem_cache_free(kmem_cache, s); 479 } 480 481 void kmem_cache_destroy(struct kmem_cache *s) 482 { 483 int err; 484 485 if (unlikely(!s)) 486 return; 487 488 get_online_cpus(); 489 get_online_mems(); 490 491 mutex_lock(&slab_mutex); 492 493 s->refcount--; 494 if (s->refcount) 495 goto out_unlock; 496 497 err = shutdown_cache(s); 498 if (err) { 499 pr_err("kmem_cache_destroy %s: Slab cache still has objects\n", 500 s->name); 501 dump_stack(); 502 } 503 out_unlock: 504 mutex_unlock(&slab_mutex); 505 506 put_online_mems(); 507 put_online_cpus(); 508 } 509 EXPORT_SYMBOL(kmem_cache_destroy); 510 511 /** 512 * kmem_cache_shrink - Shrink a cache. 513 * @cachep: The cache to shrink. 514 * 515 * Releases as many slabs as possible for a cache. 516 * To help debugging, a zero exit status indicates all slabs were released. 517 * 518 * Return: %0 if all slabs were released, non-zero otherwise 519 */ 520 int kmem_cache_shrink(struct kmem_cache *cachep) 521 { 522 int ret; 523 524 get_online_cpus(); 525 get_online_mems(); 526 kasan_cache_shrink(cachep); 527 ret = __kmem_cache_shrink(cachep); 528 put_online_mems(); 529 put_online_cpus(); 530 return ret; 531 } 532 EXPORT_SYMBOL(kmem_cache_shrink); 533 534 bool slab_is_available(void) 535 { 536 return slab_state >= UP; 537 } 538 539 #ifndef CONFIG_SLOB 540 /* Create a cache during boot when no slab services are available yet */ 541 void __init create_boot_cache(struct kmem_cache *s, const char *name, 542 unsigned int size, slab_flags_t flags, 543 unsigned int useroffset, unsigned int usersize) 544 { 545 int err; 546 unsigned int align = ARCH_KMALLOC_MINALIGN; 547 548 s->name = name; 549 s->size = s->object_size = size; 550 551 /* 552 * For power of two sizes, guarantee natural alignment for kmalloc 553 * caches, regardless of SL*B debugging options. 554 */ 555 if (is_power_of_2(size)) 556 align = max(align, size); 557 s->align = calculate_alignment(flags, align, size); 558 559 s->useroffset = useroffset; 560 s->usersize = usersize; 561 562 err = __kmem_cache_create(s, flags); 563 564 if (err) 565 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 566 name, size, err); 567 568 s->refcount = -1; /* Exempt from merging for now */ 569 } 570 571 struct kmem_cache *__init create_kmalloc_cache(const char *name, 572 unsigned int size, slab_flags_t flags, 573 unsigned int useroffset, unsigned int usersize) 574 { 575 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 576 577 if (!s) 578 panic("Out of memory when creating slab %s\n", name); 579 580 create_boot_cache(s, name, size, flags, useroffset, usersize); 581 list_add(&s->list, &slab_caches); 582 s->refcount = 1; 583 return s; 584 } 585 586 struct kmem_cache * 587 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 588 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 589 EXPORT_SYMBOL(kmalloc_caches); 590 591 /* 592 * Conversion table for small slabs sizes / 8 to the index in the 593 * kmalloc array. This is necessary for slabs < 192 since we have non power 594 * of two cache sizes there. The size of larger slabs can be determined using 595 * fls. 596 */ 597 static u8 size_index[24] __ro_after_init = { 598 3, /* 8 */ 599 4, /* 16 */ 600 5, /* 24 */ 601 5, /* 32 */ 602 6, /* 40 */ 603 6, /* 48 */ 604 6, /* 56 */ 605 6, /* 64 */ 606 1, /* 72 */ 607 1, /* 80 */ 608 1, /* 88 */ 609 1, /* 96 */ 610 7, /* 104 */ 611 7, /* 112 */ 612 7, /* 120 */ 613 7, /* 128 */ 614 2, /* 136 */ 615 2, /* 144 */ 616 2, /* 152 */ 617 2, /* 160 */ 618 2, /* 168 */ 619 2, /* 176 */ 620 2, /* 184 */ 621 2 /* 192 */ 622 }; 623 624 static inline unsigned int size_index_elem(unsigned int bytes) 625 { 626 return (bytes - 1) / 8; 627 } 628 629 /* 630 * Find the kmem_cache structure that serves a given size of 631 * allocation 632 */ 633 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 634 { 635 unsigned int index; 636 637 if (size <= 192) { 638 if (!size) 639 return ZERO_SIZE_PTR; 640 641 index = size_index[size_index_elem(size)]; 642 } else { 643 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 644 return NULL; 645 index = fls(size - 1); 646 } 647 648 return kmalloc_caches[kmalloc_type(flags)][index]; 649 } 650 651 #ifdef CONFIG_ZONE_DMA 652 #define INIT_KMALLOC_INFO(__size, __short_size) \ 653 { \ 654 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 655 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 656 .name[KMALLOC_DMA] = "dma-kmalloc-" #__short_size, \ 657 .size = __size, \ 658 } 659 #else 660 #define INIT_KMALLOC_INFO(__size, __short_size) \ 661 { \ 662 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 663 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 664 .size = __size, \ 665 } 666 #endif 667 668 /* 669 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 670 * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is 671 * kmalloc-67108864. 672 */ 673 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 674 INIT_KMALLOC_INFO(0, 0), 675 INIT_KMALLOC_INFO(96, 96), 676 INIT_KMALLOC_INFO(192, 192), 677 INIT_KMALLOC_INFO(8, 8), 678 INIT_KMALLOC_INFO(16, 16), 679 INIT_KMALLOC_INFO(32, 32), 680 INIT_KMALLOC_INFO(64, 64), 681 INIT_KMALLOC_INFO(128, 128), 682 INIT_KMALLOC_INFO(256, 256), 683 INIT_KMALLOC_INFO(512, 512), 684 INIT_KMALLOC_INFO(1024, 1k), 685 INIT_KMALLOC_INFO(2048, 2k), 686 INIT_KMALLOC_INFO(4096, 4k), 687 INIT_KMALLOC_INFO(8192, 8k), 688 INIT_KMALLOC_INFO(16384, 16k), 689 INIT_KMALLOC_INFO(32768, 32k), 690 INIT_KMALLOC_INFO(65536, 64k), 691 INIT_KMALLOC_INFO(131072, 128k), 692 INIT_KMALLOC_INFO(262144, 256k), 693 INIT_KMALLOC_INFO(524288, 512k), 694 INIT_KMALLOC_INFO(1048576, 1M), 695 INIT_KMALLOC_INFO(2097152, 2M), 696 INIT_KMALLOC_INFO(4194304, 4M), 697 INIT_KMALLOC_INFO(8388608, 8M), 698 INIT_KMALLOC_INFO(16777216, 16M), 699 INIT_KMALLOC_INFO(33554432, 32M), 700 INIT_KMALLOC_INFO(67108864, 64M) 701 }; 702 703 /* 704 * Patch up the size_index table if we have strange large alignment 705 * requirements for the kmalloc array. This is only the case for 706 * MIPS it seems. The standard arches will not generate any code here. 707 * 708 * Largest permitted alignment is 256 bytes due to the way we 709 * handle the index determination for the smaller caches. 710 * 711 * Make sure that nothing crazy happens if someone starts tinkering 712 * around with ARCH_KMALLOC_MINALIGN 713 */ 714 void __init setup_kmalloc_cache_index_table(void) 715 { 716 unsigned int i; 717 718 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 719 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); 720 721 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 722 unsigned int elem = size_index_elem(i); 723 724 if (elem >= ARRAY_SIZE(size_index)) 725 break; 726 size_index[elem] = KMALLOC_SHIFT_LOW; 727 } 728 729 if (KMALLOC_MIN_SIZE >= 64) { 730 /* 731 * The 96 byte size cache is not used if the alignment 732 * is 64 byte. 733 */ 734 for (i = 64 + 8; i <= 96; i += 8) 735 size_index[size_index_elem(i)] = 7; 736 737 } 738 739 if (KMALLOC_MIN_SIZE >= 128) { 740 /* 741 * The 192 byte sized cache is not used if the alignment 742 * is 128 byte. Redirect kmalloc to use the 256 byte cache 743 * instead. 744 */ 745 for (i = 128 + 8; i <= 192; i += 8) 746 size_index[size_index_elem(i)] = 8; 747 } 748 } 749 750 static void __init 751 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 752 { 753 if (type == KMALLOC_RECLAIM) 754 flags |= SLAB_RECLAIM_ACCOUNT; 755 756 kmalloc_caches[type][idx] = create_kmalloc_cache( 757 kmalloc_info[idx].name[type], 758 kmalloc_info[idx].size, flags, 0, 759 kmalloc_info[idx].size); 760 } 761 762 /* 763 * Create the kmalloc array. Some of the regular kmalloc arrays 764 * may already have been created because they were needed to 765 * enable allocations for slab creation. 766 */ 767 void __init create_kmalloc_caches(slab_flags_t flags) 768 { 769 int i; 770 enum kmalloc_cache_type type; 771 772 for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) { 773 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 774 if (!kmalloc_caches[type][i]) 775 new_kmalloc_cache(i, type, flags); 776 777 /* 778 * Caches that are not of the two-to-the-power-of size. 779 * These have to be created immediately after the 780 * earlier power of two caches 781 */ 782 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 783 !kmalloc_caches[type][1]) 784 new_kmalloc_cache(1, type, flags); 785 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 786 !kmalloc_caches[type][2]) 787 new_kmalloc_cache(2, type, flags); 788 } 789 } 790 791 /* Kmalloc array is now usable */ 792 slab_state = UP; 793 794 #ifdef CONFIG_ZONE_DMA 795 for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { 796 struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i]; 797 798 if (s) { 799 kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache( 800 kmalloc_info[i].name[KMALLOC_DMA], 801 kmalloc_info[i].size, 802 SLAB_CACHE_DMA | flags, 0, 803 kmalloc_info[i].size); 804 } 805 } 806 #endif 807 } 808 #endif /* !CONFIG_SLOB */ 809 810 gfp_t kmalloc_fix_flags(gfp_t flags) 811 { 812 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 813 814 flags &= ~GFP_SLAB_BUG_MASK; 815 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 816 invalid_mask, &invalid_mask, flags, &flags); 817 dump_stack(); 818 819 return flags; 820 } 821 822 /* 823 * To avoid unnecessary overhead, we pass through large allocation requests 824 * directly to the page allocator. We use __GFP_COMP, because we will need to 825 * know the allocation order to free the pages properly in kfree. 826 */ 827 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 828 { 829 void *ret = NULL; 830 struct page *page; 831 832 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 833 flags = kmalloc_fix_flags(flags); 834 835 flags |= __GFP_COMP; 836 page = alloc_pages(flags, order); 837 if (likely(page)) { 838 ret = page_address(page); 839 mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B, 840 PAGE_SIZE << order); 841 } 842 ret = kasan_kmalloc_large(ret, size, flags); 843 /* As ret might get tagged, call kmemleak hook after KASAN. */ 844 kmemleak_alloc(ret, size, 1, flags); 845 return ret; 846 } 847 EXPORT_SYMBOL(kmalloc_order); 848 849 #ifdef CONFIG_TRACING 850 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) 851 { 852 void *ret = kmalloc_order(size, flags, order); 853 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags); 854 return ret; 855 } 856 EXPORT_SYMBOL(kmalloc_order_trace); 857 #endif 858 859 #ifdef CONFIG_SLAB_FREELIST_RANDOM 860 /* Randomize a generic freelist */ 861 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 862 unsigned int count) 863 { 864 unsigned int rand; 865 unsigned int i; 866 867 for (i = 0; i < count; i++) 868 list[i] = i; 869 870 /* Fisher-Yates shuffle */ 871 for (i = count - 1; i > 0; i--) { 872 rand = prandom_u32_state(state); 873 rand %= (i + 1); 874 swap(list[i], list[rand]); 875 } 876 } 877 878 /* Create a random sequence per cache */ 879 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 880 gfp_t gfp) 881 { 882 struct rnd_state state; 883 884 if (count < 2 || cachep->random_seq) 885 return 0; 886 887 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 888 if (!cachep->random_seq) 889 return -ENOMEM; 890 891 /* Get best entropy at this stage of boot */ 892 prandom_seed_state(&state, get_random_long()); 893 894 freelist_randomize(&state, cachep->random_seq, count); 895 return 0; 896 } 897 898 /* Destroy the per-cache random freelist sequence */ 899 void cache_random_seq_destroy(struct kmem_cache *cachep) 900 { 901 kfree(cachep->random_seq); 902 cachep->random_seq = NULL; 903 } 904 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 905 906 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 907 #ifdef CONFIG_SLAB 908 #define SLABINFO_RIGHTS (0600) 909 #else 910 #define SLABINFO_RIGHTS (0400) 911 #endif 912 913 static void print_slabinfo_header(struct seq_file *m) 914 { 915 /* 916 * Output format version, so at least we can change it 917 * without _too_ many complaints. 918 */ 919 #ifdef CONFIG_DEBUG_SLAB 920 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 921 #else 922 seq_puts(m, "slabinfo - version: 2.1\n"); 923 #endif 924 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 925 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 926 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 927 #ifdef CONFIG_DEBUG_SLAB 928 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 929 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 930 #endif 931 seq_putc(m, '\n'); 932 } 933 934 void *slab_start(struct seq_file *m, loff_t *pos) 935 { 936 mutex_lock(&slab_mutex); 937 return seq_list_start(&slab_caches, *pos); 938 } 939 940 void *slab_next(struct seq_file *m, void *p, loff_t *pos) 941 { 942 return seq_list_next(p, &slab_caches, pos); 943 } 944 945 void slab_stop(struct seq_file *m, void *p) 946 { 947 mutex_unlock(&slab_mutex); 948 } 949 950 static void cache_show(struct kmem_cache *s, struct seq_file *m) 951 { 952 struct slabinfo sinfo; 953 954 memset(&sinfo, 0, sizeof(sinfo)); 955 get_slabinfo(s, &sinfo); 956 957 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 958 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 959 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 960 961 seq_printf(m, " : tunables %4u %4u %4u", 962 sinfo.limit, sinfo.batchcount, sinfo.shared); 963 seq_printf(m, " : slabdata %6lu %6lu %6lu", 964 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 965 slabinfo_show_stats(m, s); 966 seq_putc(m, '\n'); 967 } 968 969 static int slab_show(struct seq_file *m, void *p) 970 { 971 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 972 973 if (p == slab_caches.next) 974 print_slabinfo_header(m); 975 cache_show(s, m); 976 return 0; 977 } 978 979 void dump_unreclaimable_slab(void) 980 { 981 struct kmem_cache *s, *s2; 982 struct slabinfo sinfo; 983 984 /* 985 * Here acquiring slab_mutex is risky since we don't prefer to get 986 * sleep in oom path. But, without mutex hold, it may introduce a 987 * risk of crash. 988 * Use mutex_trylock to protect the list traverse, dump nothing 989 * without acquiring the mutex. 990 */ 991 if (!mutex_trylock(&slab_mutex)) { 992 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 993 return; 994 } 995 996 pr_info("Unreclaimable slab info:\n"); 997 pr_info("Name Used Total\n"); 998 999 list_for_each_entry_safe(s, s2, &slab_caches, list) { 1000 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1001 continue; 1002 1003 get_slabinfo(s, &sinfo); 1004 1005 if (sinfo.num_objs > 0) 1006 pr_info("%-17s %10luKB %10luKB\n", s->name, 1007 (sinfo.active_objs * s->size) / 1024, 1008 (sinfo.num_objs * s->size) / 1024); 1009 } 1010 mutex_unlock(&slab_mutex); 1011 } 1012 1013 #if defined(CONFIG_MEMCG_KMEM) 1014 int memcg_slab_show(struct seq_file *m, void *p) 1015 { 1016 /* 1017 * Deprecated. 1018 * Please, take a look at tools/cgroup/slabinfo.py . 1019 */ 1020 return 0; 1021 } 1022 #endif 1023 1024 /* 1025 * slabinfo_op - iterator that generates /proc/slabinfo 1026 * 1027 * Output layout: 1028 * cache-name 1029 * num-active-objs 1030 * total-objs 1031 * object size 1032 * num-active-slabs 1033 * total-slabs 1034 * num-pages-per-slab 1035 * + further values on SMP and with statistics enabled 1036 */ 1037 static const struct seq_operations slabinfo_op = { 1038 .start = slab_start, 1039 .next = slab_next, 1040 .stop = slab_stop, 1041 .show = slab_show, 1042 }; 1043 1044 static int slabinfo_open(struct inode *inode, struct file *file) 1045 { 1046 return seq_open(file, &slabinfo_op); 1047 } 1048 1049 static const struct proc_ops slabinfo_proc_ops = { 1050 .proc_flags = PROC_ENTRY_PERMANENT, 1051 .proc_open = slabinfo_open, 1052 .proc_read = seq_read, 1053 .proc_write = slabinfo_write, 1054 .proc_lseek = seq_lseek, 1055 .proc_release = seq_release, 1056 }; 1057 1058 static int __init slab_proc_init(void) 1059 { 1060 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1061 return 0; 1062 } 1063 module_init(slab_proc_init); 1064 1065 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1066 1067 static __always_inline void *__do_krealloc(const void *p, size_t new_size, 1068 gfp_t flags) 1069 { 1070 void *ret; 1071 size_t ks; 1072 1073 ks = ksize(p); 1074 1075 if (ks >= new_size) { 1076 p = kasan_krealloc((void *)p, new_size, flags); 1077 return (void *)p; 1078 } 1079 1080 ret = kmalloc_track_caller(new_size, flags); 1081 if (ret && p) 1082 memcpy(ret, p, ks); 1083 1084 return ret; 1085 } 1086 1087 /** 1088 * krealloc - reallocate memory. The contents will remain unchanged. 1089 * @p: object to reallocate memory for. 1090 * @new_size: how many bytes of memory are required. 1091 * @flags: the type of memory to allocate. 1092 * 1093 * The contents of the object pointed to are preserved up to the 1094 * lesser of the new and old sizes. If @p is %NULL, krealloc() 1095 * behaves exactly like kmalloc(). If @new_size is 0 and @p is not a 1096 * %NULL pointer, the object pointed to is freed. 1097 * 1098 * Return: pointer to the allocated memory or %NULL in case of error 1099 */ 1100 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1101 { 1102 void *ret; 1103 1104 if (unlikely(!new_size)) { 1105 kfree(p); 1106 return ZERO_SIZE_PTR; 1107 } 1108 1109 ret = __do_krealloc(p, new_size, flags); 1110 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1111 kfree(p); 1112 1113 return ret; 1114 } 1115 EXPORT_SYMBOL(krealloc); 1116 1117 /** 1118 * kfree_sensitive - Clear sensitive information in memory before freeing 1119 * @p: object to free memory of 1120 * 1121 * The memory of the object @p points to is zeroed before freed. 1122 * If @p is %NULL, kfree_sensitive() does nothing. 1123 * 1124 * Note: this function zeroes the whole allocated buffer which can be a good 1125 * deal bigger than the requested buffer size passed to kmalloc(). So be 1126 * careful when using this function in performance sensitive code. 1127 */ 1128 void kfree_sensitive(const void *p) 1129 { 1130 size_t ks; 1131 void *mem = (void *)p; 1132 1133 ks = ksize(mem); 1134 if (ks) 1135 memzero_explicit(mem, ks); 1136 kfree(mem); 1137 } 1138 EXPORT_SYMBOL(kfree_sensitive); 1139 1140 /** 1141 * ksize - get the actual amount of memory allocated for a given object 1142 * @objp: Pointer to the object 1143 * 1144 * kmalloc may internally round up allocations and return more memory 1145 * than requested. ksize() can be used to determine the actual amount of 1146 * memory allocated. The caller may use this additional memory, even though 1147 * a smaller amount of memory was initially specified with the kmalloc call. 1148 * The caller must guarantee that objp points to a valid object previously 1149 * allocated with either kmalloc() or kmem_cache_alloc(). The object 1150 * must not be freed during the duration of the call. 1151 * 1152 * Return: size of the actual memory used by @objp in bytes 1153 */ 1154 size_t ksize(const void *objp) 1155 { 1156 size_t size; 1157 1158 /* 1159 * We need to check that the pointed to object is valid, and only then 1160 * unpoison the shadow memory below. We use __kasan_check_read(), to 1161 * generate a more useful report at the time ksize() is called (rather 1162 * than later where behaviour is undefined due to potential 1163 * use-after-free or double-free). 1164 * 1165 * If the pointed to memory is invalid we return 0, to avoid users of 1166 * ksize() writing to and potentially corrupting the memory region. 1167 * 1168 * We want to perform the check before __ksize(), to avoid potentially 1169 * crashing in __ksize() due to accessing invalid metadata. 1170 */ 1171 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !__kasan_check_read(objp, 1)) 1172 return 0; 1173 1174 size = __ksize(objp); 1175 /* 1176 * We assume that ksize callers could use whole allocated area, 1177 * so we need to unpoison this area. 1178 */ 1179 kasan_unpoison_shadow(objp, size); 1180 return size; 1181 } 1182 EXPORT_SYMBOL(ksize); 1183 1184 /* Tracepoints definitions. */ 1185 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1186 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1187 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 1188 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 1189 EXPORT_TRACEPOINT_SYMBOL(kfree); 1190 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1191 1192 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1193 { 1194 if (__should_failslab(s, gfpflags)) 1195 return -ENOMEM; 1196 return 0; 1197 } 1198 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1199