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 <linux/kasan.h> 22 #include <asm/cacheflush.h> 23 #include <asm/tlbflush.h> 24 #include <asm/page.h> 25 #include <linux/memcontrol.h> 26 27 #define CREATE_TRACE_POINTS 28 #include <trace/events/kmem.h> 29 30 #include "internal.h" 31 32 #include "slab.h" 33 34 enum slab_state slab_state; 35 LIST_HEAD(slab_caches); 36 DEFINE_MUTEX(slab_mutex); 37 struct kmem_cache *kmem_cache; 38 39 #ifdef CONFIG_HARDENED_USERCOPY 40 bool usercopy_fallback __ro_after_init = 41 IS_ENABLED(CONFIG_HARDENED_USERCOPY_FALLBACK); 42 module_param(usercopy_fallback, bool, 0400); 43 MODULE_PARM_DESC(usercopy_fallback, 44 "WARN instead of reject usercopy whitelist violations"); 45 #endif 46 47 static LIST_HEAD(slab_caches_to_rcu_destroy); 48 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 49 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 50 slab_caches_to_rcu_destroy_workfn); 51 52 /* 53 * Set of flags that will prevent slab merging 54 */ 55 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 56 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 57 SLAB_FAILSLAB | kasan_never_merge()) 58 59 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 60 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 61 62 /* 63 * Merge control. If this is set then no merging of slab caches will occur. 64 */ 65 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 66 67 static int __init setup_slab_nomerge(char *str) 68 { 69 slab_nomerge = true; 70 return 1; 71 } 72 73 #ifdef CONFIG_SLUB 74 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 75 #endif 76 77 __setup("slab_nomerge", setup_slab_nomerge); 78 79 /* 80 * Determine the size of a slab object 81 */ 82 unsigned int kmem_cache_size(struct kmem_cache *s) 83 { 84 return s->object_size; 85 } 86 EXPORT_SYMBOL(kmem_cache_size); 87 88 #ifdef CONFIG_DEBUG_VM 89 static int kmem_cache_sanity_check(const char *name, unsigned int size) 90 { 91 if (!name || in_interrupt() || size < sizeof(void *) || 92 size > KMALLOC_MAX_SIZE) { 93 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 94 return -EINVAL; 95 } 96 97 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 98 return 0; 99 } 100 #else 101 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 102 { 103 return 0; 104 } 105 #endif 106 107 void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p) 108 { 109 size_t i; 110 111 for (i = 0; i < nr; i++) { 112 if (s) 113 kmem_cache_free(s, p[i]); 114 else 115 kfree(p[i]); 116 } 117 } 118 119 int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, 120 void **p) 121 { 122 size_t i; 123 124 for (i = 0; i < nr; i++) { 125 void *x = p[i] = kmem_cache_alloc(s, flags); 126 if (!x) { 127 __kmem_cache_free_bulk(s, i, p); 128 return 0; 129 } 130 } 131 return i; 132 } 133 134 /* 135 * Figure out what the alignment of the objects will be given a set of 136 * flags, a user specified alignment and the size of the objects. 137 */ 138 static unsigned int calculate_alignment(slab_flags_t flags, 139 unsigned int align, unsigned int size) 140 { 141 /* 142 * If the user wants hardware cache aligned objects then follow that 143 * suggestion if the object is sufficiently large. 144 * 145 * The hardware cache alignment cannot override the specified 146 * alignment though. If that is greater then use it. 147 */ 148 if (flags & SLAB_HWCACHE_ALIGN) { 149 unsigned int ralign; 150 151 ralign = cache_line_size(); 152 while (size <= ralign / 2) 153 ralign /= 2; 154 align = max(align, ralign); 155 } 156 157 if (align < ARCH_SLAB_MINALIGN) 158 align = ARCH_SLAB_MINALIGN; 159 160 return ALIGN(align, sizeof(void *)); 161 } 162 163 /* 164 * Find a mergeable slab cache 165 */ 166 int slab_unmergeable(struct kmem_cache *s) 167 { 168 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 169 return 1; 170 171 if (s->ctor) 172 return 1; 173 174 if (s->usersize) 175 return 1; 176 177 /* 178 * We may have set a slab to be unmergeable during bootstrap. 179 */ 180 if (s->refcount < 0) 181 return 1; 182 183 return 0; 184 } 185 186 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 187 slab_flags_t flags, const char *name, void (*ctor)(void *)) 188 { 189 struct kmem_cache *s; 190 191 if (slab_nomerge) 192 return NULL; 193 194 if (ctor) 195 return NULL; 196 197 size = ALIGN(size, sizeof(void *)); 198 align = calculate_alignment(flags, align, size); 199 size = ALIGN(size, align); 200 flags = kmem_cache_flags(size, flags, name, NULL); 201 202 if (flags & SLAB_NEVER_MERGE) 203 return NULL; 204 205 list_for_each_entry_reverse(s, &slab_caches, list) { 206 if (slab_unmergeable(s)) 207 continue; 208 209 if (size > s->size) 210 continue; 211 212 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 213 continue; 214 /* 215 * Check if alignment is compatible. 216 * Courtesy of Adrian Drzewiecki 217 */ 218 if ((s->size & ~(align - 1)) != s->size) 219 continue; 220 221 if (s->size - size >= sizeof(void *)) 222 continue; 223 224 if (IS_ENABLED(CONFIG_SLAB) && align && 225 (align > s->align || s->align % align)) 226 continue; 227 228 return s; 229 } 230 return NULL; 231 } 232 233 static struct kmem_cache *create_cache(const char *name, 234 unsigned int object_size, unsigned int align, 235 slab_flags_t flags, unsigned int useroffset, 236 unsigned int usersize, void (*ctor)(void *), 237 struct kmem_cache *root_cache) 238 { 239 struct kmem_cache *s; 240 int err; 241 242 if (WARN_ON(useroffset + usersize > object_size)) 243 useroffset = usersize = 0; 244 245 err = -ENOMEM; 246 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 247 if (!s) 248 goto out; 249 250 s->name = name; 251 s->size = s->object_size = object_size; 252 s->align = align; 253 s->ctor = ctor; 254 s->useroffset = useroffset; 255 s->usersize = usersize; 256 257 err = __kmem_cache_create(s, flags); 258 if (err) 259 goto out_free_cache; 260 261 s->refcount = 1; 262 list_add(&s->list, &slab_caches); 263 out: 264 if (err) 265 return ERR_PTR(err); 266 return s; 267 268 out_free_cache: 269 kmem_cache_free(kmem_cache, s); 270 goto out; 271 } 272 273 /** 274 * kmem_cache_create_usercopy - Create a cache with a region suitable 275 * for copying to userspace 276 * @name: A string which is used in /proc/slabinfo to identify this cache. 277 * @size: The size of objects to be created in this cache. 278 * @align: The required alignment for the objects. 279 * @flags: SLAB flags 280 * @useroffset: Usercopy region offset 281 * @usersize: Usercopy region size 282 * @ctor: A constructor for the objects. 283 * 284 * Cannot be called within a interrupt, but can be interrupted. 285 * The @ctor is run when new pages are allocated by the cache. 286 * 287 * The flags are 288 * 289 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 290 * to catch references to uninitialised memory. 291 * 292 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 293 * for buffer overruns. 294 * 295 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 296 * cacheline. This can be beneficial if you're counting cycles as closely 297 * as davem. 298 * 299 * Return: a pointer to the cache on success, NULL on failure. 300 */ 301 struct kmem_cache * 302 kmem_cache_create_usercopy(const char *name, 303 unsigned int size, unsigned int align, 304 slab_flags_t flags, 305 unsigned int useroffset, unsigned int usersize, 306 void (*ctor)(void *)) 307 { 308 struct kmem_cache *s = NULL; 309 const char *cache_name; 310 int err; 311 312 get_online_cpus(); 313 get_online_mems(); 314 315 mutex_lock(&slab_mutex); 316 317 err = kmem_cache_sanity_check(name, size); 318 if (err) { 319 goto out_unlock; 320 } 321 322 /* Refuse requests with allocator specific flags */ 323 if (flags & ~SLAB_FLAGS_PERMITTED) { 324 err = -EINVAL; 325 goto out_unlock; 326 } 327 328 /* 329 * Some allocators will constraint the set of valid flags to a subset 330 * of all flags. We expect them to define CACHE_CREATE_MASK in this 331 * case, and we'll just provide them with a sanitized version of the 332 * passed flags. 333 */ 334 flags &= CACHE_CREATE_MASK; 335 336 /* Fail closed on bad usersize of useroffset values. */ 337 if (WARN_ON(!usersize && useroffset) || 338 WARN_ON(size < usersize || size - usersize < useroffset)) 339 usersize = useroffset = 0; 340 341 if (!usersize) 342 s = __kmem_cache_alias(name, size, align, flags, ctor); 343 if (s) 344 goto out_unlock; 345 346 cache_name = kstrdup_const(name, GFP_KERNEL); 347 if (!cache_name) { 348 err = -ENOMEM; 349 goto out_unlock; 350 } 351 352 s = create_cache(cache_name, size, 353 calculate_alignment(flags, align, size), 354 flags, useroffset, usersize, ctor, NULL); 355 if (IS_ERR(s)) { 356 err = PTR_ERR(s); 357 kfree_const(cache_name); 358 } 359 360 out_unlock: 361 mutex_unlock(&slab_mutex); 362 363 put_online_mems(); 364 put_online_cpus(); 365 366 if (err) { 367 if (flags & SLAB_PANIC) 368 panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n", 369 name, err); 370 else { 371 pr_warn("kmem_cache_create(%s) failed with error %d\n", 372 name, err); 373 dump_stack(); 374 } 375 return NULL; 376 } 377 return s; 378 } 379 EXPORT_SYMBOL(kmem_cache_create_usercopy); 380 381 /** 382 * kmem_cache_create - Create a cache. 383 * @name: A string which is used in /proc/slabinfo to identify this cache. 384 * @size: The size of objects to be created in this cache. 385 * @align: The required alignment for the objects. 386 * @flags: SLAB flags 387 * @ctor: A constructor for the objects. 388 * 389 * Cannot be called within a interrupt, but can be interrupted. 390 * The @ctor is run when new pages are allocated by the cache. 391 * 392 * The flags are 393 * 394 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 395 * to catch references to uninitialised memory. 396 * 397 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 398 * for buffer overruns. 399 * 400 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 401 * cacheline. This can be beneficial if you're counting cycles as closely 402 * as davem. 403 * 404 * Return: a pointer to the cache on success, NULL on failure. 405 */ 406 struct kmem_cache * 407 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 408 slab_flags_t flags, void (*ctor)(void *)) 409 { 410 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 411 ctor); 412 } 413 EXPORT_SYMBOL(kmem_cache_create); 414 415 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 416 { 417 LIST_HEAD(to_destroy); 418 struct kmem_cache *s, *s2; 419 420 /* 421 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 422 * @slab_caches_to_rcu_destroy list. The slab pages are freed 423 * through RCU and the associated kmem_cache are dereferenced 424 * while freeing the pages, so the kmem_caches should be freed only 425 * after the pending RCU operations are finished. As rcu_barrier() 426 * is a pretty slow operation, we batch all pending destructions 427 * asynchronously. 428 */ 429 mutex_lock(&slab_mutex); 430 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 431 mutex_unlock(&slab_mutex); 432 433 if (list_empty(&to_destroy)) 434 return; 435 436 rcu_barrier(); 437 438 list_for_each_entry_safe(s, s2, &to_destroy, list) { 439 #ifdef SLAB_SUPPORTS_SYSFS 440 sysfs_slab_release(s); 441 #else 442 slab_kmem_cache_release(s); 443 #endif 444 } 445 } 446 447 static int shutdown_cache(struct kmem_cache *s) 448 { 449 /* free asan quarantined objects */ 450 kasan_cache_shutdown(s); 451 452 if (__kmem_cache_shutdown(s) != 0) 453 return -EBUSY; 454 455 list_del(&s->list); 456 457 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 458 #ifdef SLAB_SUPPORTS_SYSFS 459 sysfs_slab_unlink(s); 460 #endif 461 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 462 schedule_work(&slab_caches_to_rcu_destroy_work); 463 } else { 464 #ifdef SLAB_SUPPORTS_SYSFS 465 sysfs_slab_unlink(s); 466 sysfs_slab_release(s); 467 #else 468 slab_kmem_cache_release(s); 469 #endif 470 } 471 472 return 0; 473 } 474 475 void slab_kmem_cache_release(struct kmem_cache *s) 476 { 477 __kmem_cache_release(s); 478 kfree_const(s->name); 479 kmem_cache_free(kmem_cache, s); 480 } 481 482 void kmem_cache_destroy(struct kmem_cache *s) 483 { 484 int err; 485 486 if (unlikely(!s)) 487 return; 488 489 get_online_cpus(); 490 get_online_mems(); 491 492 mutex_lock(&slab_mutex); 493 494 s->refcount--; 495 if (s->refcount) 496 goto out_unlock; 497 498 err = shutdown_cache(s); 499 if (err) { 500 pr_err("kmem_cache_destroy %s: Slab cache still has objects\n", 501 s->name); 502 dump_stack(); 503 } 504 out_unlock: 505 mutex_unlock(&slab_mutex); 506 507 put_online_mems(); 508 put_online_cpus(); 509 } 510 EXPORT_SYMBOL(kmem_cache_destroy); 511 512 /** 513 * kmem_cache_shrink - Shrink a cache. 514 * @cachep: The cache to shrink. 515 * 516 * Releases as many slabs as possible for a cache. 517 * To help debugging, a zero exit status indicates all slabs were released. 518 * 519 * Return: %0 if all slabs were released, non-zero otherwise 520 */ 521 int kmem_cache_shrink(struct kmem_cache *cachep) 522 { 523 int ret; 524 525 get_online_cpus(); 526 get_online_mems(); 527 kasan_cache_shrink(cachep); 528 ret = __kmem_cache_shrink(cachep); 529 put_online_mems(); 530 put_online_cpus(); 531 return ret; 532 } 533 EXPORT_SYMBOL(kmem_cache_shrink); 534 535 bool slab_is_available(void) 536 { 537 return slab_state >= UP; 538 } 539 540 #ifndef CONFIG_SLOB 541 /* Create a cache during boot when no slab services are available yet */ 542 void __init create_boot_cache(struct kmem_cache *s, const char *name, 543 unsigned int size, slab_flags_t flags, 544 unsigned int useroffset, unsigned int usersize) 545 { 546 int err; 547 unsigned int align = ARCH_KMALLOC_MINALIGN; 548 549 s->name = name; 550 s->size = s->object_size = size; 551 552 /* 553 * For power of two sizes, guarantee natural alignment for kmalloc 554 * caches, regardless of SL*B debugging options. 555 */ 556 if (is_power_of_2(size)) 557 align = max(align, size); 558 s->align = calculate_alignment(flags, align, size); 559 560 s->useroffset = useroffset; 561 s->usersize = usersize; 562 563 err = __kmem_cache_create(s, flags); 564 565 if (err) 566 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 567 name, size, err); 568 569 s->refcount = -1; /* Exempt from merging for now */ 570 } 571 572 struct kmem_cache *__init create_kmalloc_cache(const char *name, 573 unsigned int size, slab_flags_t flags, 574 unsigned int useroffset, unsigned int usersize) 575 { 576 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 577 578 if (!s) 579 panic("Out of memory when creating slab %s\n", name); 580 581 create_boot_cache(s, name, size, flags, useroffset, usersize); 582 list_add(&s->list, &slab_caches); 583 s->refcount = 1; 584 return s; 585 } 586 587 struct kmem_cache * 588 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init = 589 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ }; 590 EXPORT_SYMBOL(kmalloc_caches); 591 592 /* 593 * Conversion table for small slabs sizes / 8 to the index in the 594 * kmalloc array. This is necessary for slabs < 192 since we have non power 595 * of two cache sizes there. The size of larger slabs can be determined using 596 * fls. 597 */ 598 static u8 size_index[24] __ro_after_init = { 599 3, /* 8 */ 600 4, /* 16 */ 601 5, /* 24 */ 602 5, /* 32 */ 603 6, /* 40 */ 604 6, /* 48 */ 605 6, /* 56 */ 606 6, /* 64 */ 607 1, /* 72 */ 608 1, /* 80 */ 609 1, /* 88 */ 610 1, /* 96 */ 611 7, /* 104 */ 612 7, /* 112 */ 613 7, /* 120 */ 614 7, /* 128 */ 615 2, /* 136 */ 616 2, /* 144 */ 617 2, /* 152 */ 618 2, /* 160 */ 619 2, /* 168 */ 620 2, /* 176 */ 621 2, /* 184 */ 622 2 /* 192 */ 623 }; 624 625 static inline unsigned int size_index_elem(unsigned int bytes) 626 { 627 return (bytes - 1) / 8; 628 } 629 630 /* 631 * Find the kmem_cache structure that serves a given size of 632 * allocation 633 */ 634 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) 635 { 636 unsigned int index; 637 638 if (size <= 192) { 639 if (!size) 640 return ZERO_SIZE_PTR; 641 642 index = size_index[size_index_elem(size)]; 643 } else { 644 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE)) 645 return NULL; 646 index = fls(size - 1); 647 } 648 649 return kmalloc_caches[kmalloc_type(flags)][index]; 650 } 651 652 #ifdef CONFIG_ZONE_DMA 653 #define INIT_KMALLOC_INFO(__size, __short_size) \ 654 { \ 655 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 656 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 657 .name[KMALLOC_DMA] = "dma-kmalloc-" #__short_size, \ 658 .size = __size, \ 659 } 660 #else 661 #define INIT_KMALLOC_INFO(__size, __short_size) \ 662 { \ 663 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 664 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \ 665 .size = __size, \ 666 } 667 #endif 668 669 /* 670 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. 671 * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is 672 * kmalloc-67108864. 673 */ 674 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 675 INIT_KMALLOC_INFO(0, 0), 676 INIT_KMALLOC_INFO(96, 96), 677 INIT_KMALLOC_INFO(192, 192), 678 INIT_KMALLOC_INFO(8, 8), 679 INIT_KMALLOC_INFO(16, 16), 680 INIT_KMALLOC_INFO(32, 32), 681 INIT_KMALLOC_INFO(64, 64), 682 INIT_KMALLOC_INFO(128, 128), 683 INIT_KMALLOC_INFO(256, 256), 684 INIT_KMALLOC_INFO(512, 512), 685 INIT_KMALLOC_INFO(1024, 1k), 686 INIT_KMALLOC_INFO(2048, 2k), 687 INIT_KMALLOC_INFO(4096, 4k), 688 INIT_KMALLOC_INFO(8192, 8k), 689 INIT_KMALLOC_INFO(16384, 16k), 690 INIT_KMALLOC_INFO(32768, 32k), 691 INIT_KMALLOC_INFO(65536, 64k), 692 INIT_KMALLOC_INFO(131072, 128k), 693 INIT_KMALLOC_INFO(262144, 256k), 694 INIT_KMALLOC_INFO(524288, 512k), 695 INIT_KMALLOC_INFO(1048576, 1M), 696 INIT_KMALLOC_INFO(2097152, 2M), 697 INIT_KMALLOC_INFO(4194304, 4M), 698 INIT_KMALLOC_INFO(8388608, 8M), 699 INIT_KMALLOC_INFO(16777216, 16M), 700 INIT_KMALLOC_INFO(33554432, 32M), 701 INIT_KMALLOC_INFO(67108864, 64M) 702 }; 703 704 /* 705 * Patch up the size_index table if we have strange large alignment 706 * requirements for the kmalloc array. This is only the case for 707 * MIPS it seems. The standard arches will not generate any code here. 708 * 709 * Largest permitted alignment is 256 bytes due to the way we 710 * handle the index determination for the smaller caches. 711 * 712 * Make sure that nothing crazy happens if someone starts tinkering 713 * around with ARCH_KMALLOC_MINALIGN 714 */ 715 void __init setup_kmalloc_cache_index_table(void) 716 { 717 unsigned int i; 718 719 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 720 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); 721 722 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 723 unsigned int elem = size_index_elem(i); 724 725 if (elem >= ARRAY_SIZE(size_index)) 726 break; 727 size_index[elem] = KMALLOC_SHIFT_LOW; 728 } 729 730 if (KMALLOC_MIN_SIZE >= 64) { 731 /* 732 * The 96 byte size cache is not used if the alignment 733 * is 64 byte. 734 */ 735 for (i = 64 + 8; i <= 96; i += 8) 736 size_index[size_index_elem(i)] = 7; 737 738 } 739 740 if (KMALLOC_MIN_SIZE >= 128) { 741 /* 742 * The 192 byte sized cache is not used if the alignment 743 * is 128 byte. Redirect kmalloc to use the 256 byte cache 744 * instead. 745 */ 746 for (i = 128 + 8; i <= 192; i += 8) 747 size_index[size_index_elem(i)] = 8; 748 } 749 } 750 751 static void __init 752 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 753 { 754 if (type == KMALLOC_RECLAIM) 755 flags |= SLAB_RECLAIM_ACCOUNT; 756 757 kmalloc_caches[type][idx] = create_kmalloc_cache( 758 kmalloc_info[idx].name[type], 759 kmalloc_info[idx].size, flags, 0, 760 kmalloc_info[idx].size); 761 } 762 763 /* 764 * Create the kmalloc array. Some of the regular kmalloc arrays 765 * may already have been created because they were needed to 766 * enable allocations for slab creation. 767 */ 768 void __init create_kmalloc_caches(slab_flags_t flags) 769 { 770 int i; 771 enum kmalloc_cache_type type; 772 773 for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) { 774 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { 775 if (!kmalloc_caches[type][i]) 776 new_kmalloc_cache(i, type, flags); 777 778 /* 779 * Caches that are not of the two-to-the-power-of size. 780 * These have to be created immediately after the 781 * earlier power of two caches 782 */ 783 if (KMALLOC_MIN_SIZE <= 32 && i == 6 && 784 !kmalloc_caches[type][1]) 785 new_kmalloc_cache(1, type, flags); 786 if (KMALLOC_MIN_SIZE <= 64 && i == 7 && 787 !kmalloc_caches[type][2]) 788 new_kmalloc_cache(2, type, flags); 789 } 790 } 791 792 /* Kmalloc array is now usable */ 793 slab_state = UP; 794 795 #ifdef CONFIG_ZONE_DMA 796 for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { 797 struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i]; 798 799 if (s) { 800 kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache( 801 kmalloc_info[i].name[KMALLOC_DMA], 802 kmalloc_info[i].size, 803 SLAB_CACHE_DMA | flags, 0, 804 kmalloc_info[i].size); 805 } 806 } 807 #endif 808 } 809 #endif /* !CONFIG_SLOB */ 810 811 gfp_t kmalloc_fix_flags(gfp_t flags) 812 { 813 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 814 815 flags &= ~GFP_SLAB_BUG_MASK; 816 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 817 invalid_mask, &invalid_mask, flags, &flags); 818 dump_stack(); 819 820 return flags; 821 } 822 823 /* 824 * To avoid unnecessary overhead, we pass through large allocation requests 825 * directly to the page allocator. We use __GFP_COMP, because we will need to 826 * know the allocation order to free the pages properly in kfree. 827 */ 828 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 829 { 830 void *ret = NULL; 831 struct page *page; 832 833 if (unlikely(flags & GFP_SLAB_BUG_MASK)) 834 flags = kmalloc_fix_flags(flags); 835 836 flags |= __GFP_COMP; 837 page = alloc_pages(flags, order); 838 if (likely(page)) { 839 ret = page_address(page); 840 mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B, 841 PAGE_SIZE << order); 842 } 843 ret = kasan_kmalloc_large(ret, size, flags); 844 /* As ret might get tagged, call kmemleak hook after KASAN. */ 845 kmemleak_alloc(ret, size, 1, flags); 846 return ret; 847 } 848 EXPORT_SYMBOL(kmalloc_order); 849 850 #ifdef CONFIG_TRACING 851 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) 852 { 853 void *ret = kmalloc_order(size, flags, order); 854 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags); 855 return ret; 856 } 857 EXPORT_SYMBOL(kmalloc_order_trace); 858 #endif 859 860 #ifdef CONFIG_SLAB_FREELIST_RANDOM 861 /* Randomize a generic freelist */ 862 static void freelist_randomize(struct rnd_state *state, unsigned int *list, 863 unsigned int count) 864 { 865 unsigned int rand; 866 unsigned int i; 867 868 for (i = 0; i < count; i++) 869 list[i] = i; 870 871 /* Fisher-Yates shuffle */ 872 for (i = count - 1; i > 0; i--) { 873 rand = prandom_u32_state(state); 874 rand %= (i + 1); 875 swap(list[i], list[rand]); 876 } 877 } 878 879 /* Create a random sequence per cache */ 880 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 881 gfp_t gfp) 882 { 883 struct rnd_state state; 884 885 if (count < 2 || cachep->random_seq) 886 return 0; 887 888 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 889 if (!cachep->random_seq) 890 return -ENOMEM; 891 892 /* Get best entropy at this stage of boot */ 893 prandom_seed_state(&state, get_random_long()); 894 895 freelist_randomize(&state, cachep->random_seq, count); 896 return 0; 897 } 898 899 /* Destroy the per-cache random freelist sequence */ 900 void cache_random_seq_destroy(struct kmem_cache *cachep) 901 { 902 kfree(cachep->random_seq); 903 cachep->random_seq = NULL; 904 } 905 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 906 907 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) 908 #ifdef CONFIG_SLAB 909 #define SLABINFO_RIGHTS (0600) 910 #else 911 #define SLABINFO_RIGHTS (0400) 912 #endif 913 914 static void print_slabinfo_header(struct seq_file *m) 915 { 916 /* 917 * Output format version, so at least we can change it 918 * without _too_ many complaints. 919 */ 920 #ifdef CONFIG_DEBUG_SLAB 921 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); 922 #else 923 seq_puts(m, "slabinfo - version: 2.1\n"); 924 #endif 925 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 926 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 927 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 928 #ifdef CONFIG_DEBUG_SLAB 929 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); 930 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); 931 #endif 932 seq_putc(m, '\n'); 933 } 934 935 void *slab_start(struct seq_file *m, loff_t *pos) 936 { 937 mutex_lock(&slab_mutex); 938 return seq_list_start(&slab_caches, *pos); 939 } 940 941 void *slab_next(struct seq_file *m, void *p, loff_t *pos) 942 { 943 return seq_list_next(p, &slab_caches, pos); 944 } 945 946 void slab_stop(struct seq_file *m, void *p) 947 { 948 mutex_unlock(&slab_mutex); 949 } 950 951 static void cache_show(struct kmem_cache *s, struct seq_file *m) 952 { 953 struct slabinfo sinfo; 954 955 memset(&sinfo, 0, sizeof(sinfo)); 956 get_slabinfo(s, &sinfo); 957 958 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 959 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 960 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 961 962 seq_printf(m, " : tunables %4u %4u %4u", 963 sinfo.limit, sinfo.batchcount, sinfo.shared); 964 seq_printf(m, " : slabdata %6lu %6lu %6lu", 965 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 966 slabinfo_show_stats(m, s); 967 seq_putc(m, '\n'); 968 } 969 970 static int slab_show(struct seq_file *m, void *p) 971 { 972 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 973 974 if (p == slab_caches.next) 975 print_slabinfo_header(m); 976 cache_show(s, m); 977 return 0; 978 } 979 980 void dump_unreclaimable_slab(void) 981 { 982 struct kmem_cache *s; 983 struct slabinfo sinfo; 984 985 /* 986 * Here acquiring slab_mutex is risky since we don't prefer to get 987 * sleep in oom path. But, without mutex hold, it may introduce a 988 * risk of crash. 989 * Use mutex_trylock to protect the list traverse, dump nothing 990 * without acquiring the mutex. 991 */ 992 if (!mutex_trylock(&slab_mutex)) { 993 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 994 return; 995 } 996 997 pr_info("Unreclaimable slab info:\n"); 998 pr_info("Name Used Total\n"); 999 1000 list_for_each_entry(s, &slab_caches, list) { 1001 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1002 continue; 1003 1004 get_slabinfo(s, &sinfo); 1005 1006 if (sinfo.num_objs > 0) 1007 pr_info("%-17s %10luKB %10luKB\n", s->name, 1008 (sinfo.active_objs * s->size) / 1024, 1009 (sinfo.num_objs * s->size) / 1024); 1010 } 1011 mutex_unlock(&slab_mutex); 1012 } 1013 1014 #if defined(CONFIG_MEMCG_KMEM) 1015 int memcg_slab_show(struct seq_file *m, void *p) 1016 { 1017 /* 1018 * Deprecated. 1019 * Please, take a look at tools/cgroup/slabinfo.py . 1020 */ 1021 return 0; 1022 } 1023 #endif 1024 1025 /* 1026 * slabinfo_op - iterator that generates /proc/slabinfo 1027 * 1028 * Output layout: 1029 * cache-name 1030 * num-active-objs 1031 * total-objs 1032 * object size 1033 * num-active-slabs 1034 * total-slabs 1035 * num-pages-per-slab 1036 * + further values on SMP and with statistics enabled 1037 */ 1038 static const struct seq_operations slabinfo_op = { 1039 .start = slab_start, 1040 .next = slab_next, 1041 .stop = slab_stop, 1042 .show = slab_show, 1043 }; 1044 1045 static int slabinfo_open(struct inode *inode, struct file *file) 1046 { 1047 return seq_open(file, &slabinfo_op); 1048 } 1049 1050 static const struct proc_ops slabinfo_proc_ops = { 1051 .proc_flags = PROC_ENTRY_PERMANENT, 1052 .proc_open = slabinfo_open, 1053 .proc_read = seq_read, 1054 .proc_write = slabinfo_write, 1055 .proc_lseek = seq_lseek, 1056 .proc_release = seq_release, 1057 }; 1058 1059 static int __init slab_proc_init(void) 1060 { 1061 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1062 return 0; 1063 } 1064 module_init(slab_proc_init); 1065 1066 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */ 1067 1068 static __always_inline void *__do_krealloc(const void *p, size_t new_size, 1069 gfp_t flags) 1070 { 1071 void *ret; 1072 size_t ks; 1073 1074 ks = ksize(p); 1075 1076 if (ks >= new_size) { 1077 p = kasan_krealloc((void *)p, new_size, flags); 1078 return (void *)p; 1079 } 1080 1081 ret = kmalloc_track_caller(new_size, flags); 1082 if (ret && p) 1083 memcpy(ret, p, ks); 1084 1085 return ret; 1086 } 1087 1088 /** 1089 * krealloc - reallocate memory. The contents will remain unchanged. 1090 * @p: object to reallocate memory for. 1091 * @new_size: how many bytes of memory are required. 1092 * @flags: the type of memory to allocate. 1093 * 1094 * The contents of the object pointed to are preserved up to the 1095 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1096 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1097 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1098 * 1099 * Return: pointer to the allocated memory or %NULL in case of error 1100 */ 1101 void *krealloc(const void *p, size_t new_size, gfp_t flags) 1102 { 1103 void *ret; 1104 1105 if (unlikely(!new_size)) { 1106 kfree(p); 1107 return ZERO_SIZE_PTR; 1108 } 1109 1110 ret = __do_krealloc(p, new_size, flags); 1111 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1112 kfree(p); 1113 1114 return ret; 1115 } 1116 EXPORT_SYMBOL(krealloc); 1117 1118 /** 1119 * kfree_sensitive - Clear sensitive information in memory before freeing 1120 * @p: object to free memory of 1121 * 1122 * The memory of the object @p points to is zeroed before freed. 1123 * If @p is %NULL, kfree_sensitive() does nothing. 1124 * 1125 * Note: this function zeroes the whole allocated buffer which can be a good 1126 * deal bigger than the requested buffer size passed to kmalloc(). So be 1127 * careful when using this function in performance sensitive code. 1128 */ 1129 void kfree_sensitive(const void *p) 1130 { 1131 size_t ks; 1132 void *mem = (void *)p; 1133 1134 ks = ksize(mem); 1135 if (ks) 1136 memzero_explicit(mem, ks); 1137 kfree(mem); 1138 } 1139 EXPORT_SYMBOL(kfree_sensitive); 1140 1141 /** 1142 * ksize - get the actual amount of memory allocated for a given object 1143 * @objp: Pointer to the object 1144 * 1145 * kmalloc may internally round up allocations and return more memory 1146 * than requested. ksize() can be used to determine the actual amount of 1147 * memory allocated. The caller may use this additional memory, even though 1148 * a smaller amount of memory was initially specified with the kmalloc call. 1149 * The caller must guarantee that objp points to a valid object previously 1150 * allocated with either kmalloc() or kmem_cache_alloc(). The object 1151 * must not be freed during the duration of the call. 1152 * 1153 * Return: size of the actual memory used by @objp in bytes 1154 */ 1155 size_t ksize(const void *objp) 1156 { 1157 size_t size; 1158 1159 /* 1160 * We need to check that the pointed to object is valid, and only then 1161 * unpoison the shadow memory below. We use __kasan_check_read(), to 1162 * generate a more useful report at the time ksize() is called (rather 1163 * than later where behaviour is undefined due to potential 1164 * use-after-free or double-free). 1165 * 1166 * If the pointed to memory is invalid we return 0, to avoid users of 1167 * ksize() writing to and potentially corrupting the memory region. 1168 * 1169 * We want to perform the check before __ksize(), to avoid potentially 1170 * crashing in __ksize() due to accessing invalid metadata. 1171 */ 1172 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !__kasan_check_read(objp, 1)) 1173 return 0; 1174 1175 size = __ksize(objp); 1176 /* 1177 * We assume that ksize callers could use whole allocated area, 1178 * so we need to unpoison this area. 1179 */ 1180 kasan_unpoison_range(objp, size); 1181 return size; 1182 } 1183 EXPORT_SYMBOL(ksize); 1184 1185 /* Tracepoints definitions. */ 1186 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1187 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1188 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 1189 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 1190 EXPORT_TRACEPOINT_SYMBOL(kfree); 1191 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1192 1193 int should_failslab(struct kmem_cache *s, gfp_t gfpflags) 1194 { 1195 if (__should_failslab(s, gfpflags)) 1196 return -ENOMEM; 1197 return 0; 1198 } 1199 ALLOW_ERROR_INJECTION(should_failslab, ERRNO); 1200