1 // SPDX-License-Identifier: GPL-2.0
3 * Slab allocator functions that are independent of the allocator strategy
5 * (C) 2012 Christoph Lameter <cl@linux.com>
7 #include <linux/slab.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/kfence.h>
16 #include <linux/module.h>
17 #include <linux/cpu.h>
18 #include <linux/uaccess.h>
19 #include <linux/seq_file.h>
20 #include <linux/proc_fs.h>
21 #include <linux/debugfs.h>
22 #include <linux/kasan.h>
23 #include <asm/cacheflush.h>
24 #include <asm/tlbflush.h>
26 #include <linux/memcontrol.h>
28 #define CREATE_TRACE_POINTS
29 #include <trace/events/kmem.h>
35 enum slab_state slab_state;
36 LIST_HEAD(slab_caches);
37 DEFINE_MUTEX(slab_mutex);
38 struct kmem_cache *kmem_cache;
40 #ifdef CONFIG_HARDENED_USERCOPY
41 bool usercopy_fallback __ro_after_init =
42 IS_ENABLED(CONFIG_HARDENED_USERCOPY_FALLBACK);
43 module_param(usercopy_fallback, bool, 0400);
44 MODULE_PARM_DESC(usercopy_fallback,
45 "WARN instead of reject usercopy whitelist violations");
48 static LIST_HEAD(slab_caches_to_rcu_destroy);
49 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work);
50 static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
51 slab_caches_to_rcu_destroy_workfn);
54 * Set of flags that will prevent slab merging
56 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
57 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
58 SLAB_FAILSLAB | kasan_never_merge())
60 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
61 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
64 * Merge control. If this is set then no merging of slab caches will occur.
66 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
68 static int __init setup_slab_nomerge(char *str)
74 static int __init setup_slab_merge(char *str)
81 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
82 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0);
85 __setup("slab_nomerge", setup_slab_nomerge);
86 __setup("slab_merge", setup_slab_merge);
89 * Determine the size of a slab object
91 unsigned int kmem_cache_size(struct kmem_cache *s)
93 return s->object_size;
95 EXPORT_SYMBOL(kmem_cache_size);
97 #ifdef CONFIG_DEBUG_VM
98 static int kmem_cache_sanity_check(const char *name, unsigned int size)
100 if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
101 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
105 WARN_ON(strchr(name, ' ')); /* It confuses parsers */
109 static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
115 void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
119 for (i = 0; i < nr; i++) {
121 kmem_cache_free(s, p[i]);
127 int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
132 for (i = 0; i < nr; i++) {
133 void *x = p[i] = kmem_cache_alloc(s, flags);
135 __kmem_cache_free_bulk(s, i, p);
143 * Figure out what the alignment of the objects will be given a set of
144 * flags, a user specified alignment and the size of the objects.
146 static unsigned int calculate_alignment(slab_flags_t flags,
147 unsigned int align, unsigned int size)
150 * If the user wants hardware cache aligned objects then follow that
151 * suggestion if the object is sufficiently large.
153 * The hardware cache alignment cannot override the specified
154 * alignment though. If that is greater then use it.
156 if (flags & SLAB_HWCACHE_ALIGN) {
159 ralign = cache_line_size();
160 while (size <= ralign / 2)
162 align = max(align, ralign);
165 if (align < ARCH_SLAB_MINALIGN)
166 align = ARCH_SLAB_MINALIGN;
168 return ALIGN(align, sizeof(void *));
172 * Find a mergeable slab cache
174 int slab_unmergeable(struct kmem_cache *s)
176 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
186 * We may have set a slab to be unmergeable during bootstrap.
194 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
195 slab_flags_t flags, const char *name, void (*ctor)(void *))
197 struct kmem_cache *s;
205 size = ALIGN(size, sizeof(void *));
206 align = calculate_alignment(flags, align, size);
207 size = ALIGN(size, align);
208 flags = kmem_cache_flags(size, flags, name);
210 if (flags & SLAB_NEVER_MERGE)
213 list_for_each_entry_reverse(s, &slab_caches, list) {
214 if (slab_unmergeable(s))
220 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
223 * Check if alignment is compatible.
224 * Courtesy of Adrian Drzewiecki
226 if ((s->size & ~(align - 1)) != s->size)
229 if (s->size - size >= sizeof(void *))
232 if (IS_ENABLED(CONFIG_SLAB) && align &&
233 (align > s->align || s->align % align))
241 static struct kmem_cache *create_cache(const char *name,
242 unsigned int object_size, unsigned int align,
243 slab_flags_t flags, unsigned int useroffset,
244 unsigned int usersize, void (*ctor)(void *),
245 struct kmem_cache *root_cache)
247 struct kmem_cache *s;
250 if (WARN_ON(useroffset + usersize > object_size))
251 useroffset = usersize = 0;
254 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
259 s->size = s->object_size = object_size;
262 s->useroffset = useroffset;
263 s->usersize = usersize;
265 err = __kmem_cache_create(s, flags);
270 list_add(&s->list, &slab_caches);
277 kmem_cache_free(kmem_cache, s);
282 * kmem_cache_create_usercopy - Create a cache with a region suitable
283 * for copying to userspace
284 * @name: A string which is used in /proc/slabinfo to identify this cache.
285 * @size: The size of objects to be created in this cache.
286 * @align: The required alignment for the objects.
288 * @useroffset: Usercopy region offset
289 * @usersize: Usercopy region size
290 * @ctor: A constructor for the objects.
292 * Cannot be called within a interrupt, but can be interrupted.
293 * The @ctor is run when new pages are allocated by the cache.
297 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
298 * to catch references to uninitialised memory.
300 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check
301 * for buffer overruns.
303 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
304 * cacheline. This can be beneficial if you're counting cycles as closely
307 * Return: a pointer to the cache on success, NULL on failure.
310 kmem_cache_create_usercopy(const char *name,
311 unsigned int size, unsigned int align,
313 unsigned int useroffset, unsigned int usersize,
314 void (*ctor)(void *))
316 struct kmem_cache *s = NULL;
317 const char *cache_name;
320 #ifdef CONFIG_SLUB_DEBUG
322 * If no slub_debug was enabled globally, the static key is not yet
323 * enabled by setup_slub_debug(). Enable it if the cache is being
324 * created with any of the debugging flags passed explicitly.
326 if (flags & SLAB_DEBUG_FLAGS)
327 static_branch_enable(&slub_debug_enabled);
330 mutex_lock(&slab_mutex);
332 err = kmem_cache_sanity_check(name, size);
337 /* Refuse requests with allocator specific flags */
338 if (flags & ~SLAB_FLAGS_PERMITTED) {
344 * Some allocators will constraint the set of valid flags to a subset
345 * of all flags. We expect them to define CACHE_CREATE_MASK in this
346 * case, and we'll just provide them with a sanitized version of the
349 flags &= CACHE_CREATE_MASK;
351 /* Fail closed on bad usersize of useroffset values. */
352 if (WARN_ON(!usersize && useroffset) ||
353 WARN_ON(size < usersize || size - usersize < useroffset))
354 usersize = useroffset = 0;
357 s = __kmem_cache_alias(name, size, align, flags, ctor);
361 cache_name = kstrdup_const(name, GFP_KERNEL);
367 s = create_cache(cache_name, size,
368 calculate_alignment(flags, align, size),
369 flags, useroffset, usersize, ctor, NULL);
372 kfree_const(cache_name);
376 mutex_unlock(&slab_mutex);
379 if (flags & SLAB_PANIC)
380 panic("%s: Failed to create slab '%s'. Error %d\n",
381 __func__, name, err);
383 pr_warn("%s(%s) failed with error %d\n",
384 __func__, name, err);
391 EXPORT_SYMBOL(kmem_cache_create_usercopy);
394 * kmem_cache_create - Create a cache.
395 * @name: A string which is used in /proc/slabinfo to identify this cache.
396 * @size: The size of objects to be created in this cache.
397 * @align: The required alignment for the objects.
399 * @ctor: A constructor for the objects.
401 * Cannot be called within a interrupt, but can be interrupted.
402 * The @ctor is run when new pages are allocated by the cache.
406 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
407 * to catch references to uninitialised memory.
409 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check
410 * for buffer overruns.
412 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
413 * cacheline. This can be beneficial if you're counting cycles as closely
416 * Return: a pointer to the cache on success, NULL on failure.
419 kmem_cache_create(const char *name, unsigned int size, unsigned int align,
420 slab_flags_t flags, void (*ctor)(void *))
422 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0,
425 EXPORT_SYMBOL(kmem_cache_create);
427 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
429 LIST_HEAD(to_destroy);
430 struct kmem_cache *s, *s2;
433 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the
434 * @slab_caches_to_rcu_destroy list. The slab pages are freed
435 * through RCU and the associated kmem_cache are dereferenced
436 * while freeing the pages, so the kmem_caches should be freed only
437 * after the pending RCU operations are finished. As rcu_barrier()
438 * is a pretty slow operation, we batch all pending destructions
441 mutex_lock(&slab_mutex);
442 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy);
443 mutex_unlock(&slab_mutex);
445 if (list_empty(&to_destroy))
450 list_for_each_entry_safe(s, s2, &to_destroy, list) {
451 debugfs_slab_release(s);
452 kfence_shutdown_cache(s);
453 #ifdef SLAB_SUPPORTS_SYSFS
454 sysfs_slab_release(s);
456 slab_kmem_cache_release(s);
461 static int shutdown_cache(struct kmem_cache *s)
463 /* free asan quarantined objects */
464 kasan_cache_shutdown(s);
466 if (__kmem_cache_shutdown(s) != 0)
471 if (s->flags & SLAB_TYPESAFE_BY_RCU) {
472 #ifdef SLAB_SUPPORTS_SYSFS
473 sysfs_slab_unlink(s);
475 list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
476 schedule_work(&slab_caches_to_rcu_destroy_work);
478 kfence_shutdown_cache(s);
479 debugfs_slab_release(s);
480 #ifdef SLAB_SUPPORTS_SYSFS
481 sysfs_slab_unlink(s);
482 sysfs_slab_release(s);
484 slab_kmem_cache_release(s);
491 void slab_kmem_cache_release(struct kmem_cache *s)
493 __kmem_cache_release(s);
494 kfree_const(s->name);
495 kmem_cache_free(kmem_cache, s);
498 void kmem_cache_destroy(struct kmem_cache *s)
506 mutex_lock(&slab_mutex);
512 err = shutdown_cache(s);
514 pr_err("%s %s: Slab cache still has objects\n",
519 mutex_unlock(&slab_mutex);
522 EXPORT_SYMBOL(kmem_cache_destroy);
525 * kmem_cache_shrink - Shrink a cache.
526 * @cachep: The cache to shrink.
528 * Releases as many slabs as possible for a cache.
529 * To help debugging, a zero exit status indicates all slabs were released.
531 * Return: %0 if all slabs were released, non-zero otherwise
533 int kmem_cache_shrink(struct kmem_cache *cachep)
538 kasan_cache_shrink(cachep);
539 ret = __kmem_cache_shrink(cachep);
543 EXPORT_SYMBOL(kmem_cache_shrink);
545 bool slab_is_available(void)
547 return slab_state >= UP;
552 * kmem_valid_obj - does the pointer reference a valid slab object?
553 * @object: pointer to query.
555 * Return: %true if the pointer is to a not-yet-freed object from
556 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
557 * is to an already-freed object, and %false otherwise.
559 bool kmem_valid_obj(void *object)
563 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */
564 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
566 page = virt_to_head_page(object);
567 return PageSlab(page);
569 EXPORT_SYMBOL_GPL(kmem_valid_obj);
571 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
573 if (__kfence_obj_info(kpp, object, page))
575 __kmem_obj_info(kpp, object, page);
579 * kmem_dump_obj - Print available slab provenance information
580 * @object: slab object for which to find provenance information.
582 * This function uses pr_cont(), so that the caller is expected to have
583 * printed out whatever preamble is appropriate. The provenance information
584 * depends on the type of object and on how much debugging is enabled.
585 * For a slab-cache object, the fact that it is a slab object is printed,
586 * and, if available, the slab name, return address, and stack trace from
587 * the allocation and last free path of that object.
589 * This function will splat if passed a pointer to a non-slab object.
590 * If you are not sure what type of object you have, you should instead
591 * use mem_dump_obj().
593 void kmem_dump_obj(void *object)
595 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
598 unsigned long ptroffset;
599 struct kmem_obj_info kp = { };
601 if (WARN_ON_ONCE(!virt_addr_valid(object)))
603 page = virt_to_head_page(object);
604 if (WARN_ON_ONCE(!PageSlab(page))) {
605 pr_cont(" non-slab memory.\n");
608 kmem_obj_info(&kp, object, page);
609 if (kp.kp_slab_cache)
610 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
612 pr_cont(" slab%s", cp);
613 if (is_kfence_address(object))
614 pr_cont(" (kfence)");
616 pr_cont(" start %px", kp.kp_objp);
617 if (kp.kp_data_offset)
618 pr_cont(" data offset %lu", kp.kp_data_offset);
620 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
621 pr_cont(" pointer offset %lu", ptroffset);
623 if (kp.kp_slab_cache && kp.kp_slab_cache->usersize)
624 pr_cont(" size %u", kp.kp_slab_cache->usersize);
626 pr_cont(" allocated at %pS\n", kp.kp_ret);
629 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
632 pr_info(" %pS\n", kp.kp_stack[i]);
635 if (kp.kp_free_stack[0])
636 pr_cont(" Free path:\n");
638 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
639 if (!kp.kp_free_stack[i])
641 pr_info(" %pS\n", kp.kp_free_stack[i]);
645 EXPORT_SYMBOL_GPL(kmem_dump_obj);
649 /* Create a cache during boot when no slab services are available yet */
650 void __init create_boot_cache(struct kmem_cache *s, const char *name,
651 unsigned int size, slab_flags_t flags,
652 unsigned int useroffset, unsigned int usersize)
655 unsigned int align = ARCH_KMALLOC_MINALIGN;
658 s->size = s->object_size = size;
661 * For power of two sizes, guarantee natural alignment for kmalloc
662 * caches, regardless of SL*B debugging options.
664 if (is_power_of_2(size))
665 align = max(align, size);
666 s->align = calculate_alignment(flags, align, size);
668 s->useroffset = useroffset;
669 s->usersize = usersize;
671 err = __kmem_cache_create(s, flags);
674 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
677 s->refcount = -1; /* Exempt from merging for now */
680 struct kmem_cache *__init create_kmalloc_cache(const char *name,
681 unsigned int size, slab_flags_t flags,
682 unsigned int useroffset, unsigned int usersize)
684 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
687 panic("Out of memory when creating slab %s\n", name);
689 create_boot_cache(s, name, size, flags, useroffset, usersize);
690 kasan_cache_create_kmalloc(s);
691 list_add(&s->list, &slab_caches);
697 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init =
698 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ };
699 EXPORT_SYMBOL(kmalloc_caches);
702 * Conversion table for small slabs sizes / 8 to the index in the
703 * kmalloc array. This is necessary for slabs < 192 since we have non power
704 * of two cache sizes there. The size of larger slabs can be determined using
707 static u8 size_index[24] __ro_after_init = {
734 static inline unsigned int size_index_elem(unsigned int bytes)
736 return (bytes - 1) / 8;
740 * Find the kmem_cache structure that serves a given size of
743 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
749 return ZERO_SIZE_PTR;
751 index = size_index[size_index_elem(size)];
753 if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE))
755 index = fls(size - 1);
758 return kmalloc_caches[kmalloc_type(flags)][index];
761 #ifdef CONFIG_ZONE_DMA
762 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
764 #define KMALLOC_DMA_NAME(sz)
767 #ifdef CONFIG_MEMCG_KMEM
768 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
770 #define KMALLOC_CGROUP_NAME(sz)
773 #define INIT_KMALLOC_INFO(__size, __short_size) \
775 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \
776 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \
777 KMALLOC_CGROUP_NAME(__short_size) \
778 KMALLOC_DMA_NAME(__short_size) \
783 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
784 * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is
787 const struct kmalloc_info_struct kmalloc_info[] __initconst = {
788 INIT_KMALLOC_INFO(0, 0),
789 INIT_KMALLOC_INFO(96, 96),
790 INIT_KMALLOC_INFO(192, 192),
791 INIT_KMALLOC_INFO(8, 8),
792 INIT_KMALLOC_INFO(16, 16),
793 INIT_KMALLOC_INFO(32, 32),
794 INIT_KMALLOC_INFO(64, 64),
795 INIT_KMALLOC_INFO(128, 128),
796 INIT_KMALLOC_INFO(256, 256),
797 INIT_KMALLOC_INFO(512, 512),
798 INIT_KMALLOC_INFO(1024, 1k),
799 INIT_KMALLOC_INFO(2048, 2k),
800 INIT_KMALLOC_INFO(4096, 4k),
801 INIT_KMALLOC_INFO(8192, 8k),
802 INIT_KMALLOC_INFO(16384, 16k),
803 INIT_KMALLOC_INFO(32768, 32k),
804 INIT_KMALLOC_INFO(65536, 64k),
805 INIT_KMALLOC_INFO(131072, 128k),
806 INIT_KMALLOC_INFO(262144, 256k),
807 INIT_KMALLOC_INFO(524288, 512k),
808 INIT_KMALLOC_INFO(1048576, 1M),
809 INIT_KMALLOC_INFO(2097152, 2M),
810 INIT_KMALLOC_INFO(4194304, 4M),
811 INIT_KMALLOC_INFO(8388608, 8M),
812 INIT_KMALLOC_INFO(16777216, 16M),
813 INIT_KMALLOC_INFO(33554432, 32M)
817 * Patch up the size_index table if we have strange large alignment
818 * requirements for the kmalloc array. This is only the case for
819 * MIPS it seems. The standard arches will not generate any code here.
821 * Largest permitted alignment is 256 bytes due to the way we
822 * handle the index determination for the smaller caches.
824 * Make sure that nothing crazy happens if someone starts tinkering
825 * around with ARCH_KMALLOC_MINALIGN
827 void __init setup_kmalloc_cache_index_table(void)
831 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
832 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
834 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
835 unsigned int elem = size_index_elem(i);
837 if (elem >= ARRAY_SIZE(size_index))
839 size_index[elem] = KMALLOC_SHIFT_LOW;
842 if (KMALLOC_MIN_SIZE >= 64) {
844 * The 96 byte size cache is not used if the alignment
847 for (i = 64 + 8; i <= 96; i += 8)
848 size_index[size_index_elem(i)] = 7;
852 if (KMALLOC_MIN_SIZE >= 128) {
854 * The 192 byte sized cache is not used if the alignment
855 * is 128 byte. Redirect kmalloc to use the 256 byte cache
858 for (i = 128 + 8; i <= 192; i += 8)
859 size_index[size_index_elem(i)] = 8;
864 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
866 if (type == KMALLOC_RECLAIM) {
867 flags |= SLAB_RECLAIM_ACCOUNT;
868 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) {
869 if (cgroup_memory_nokmem) {
870 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx];
873 flags |= SLAB_ACCOUNT;
876 kmalloc_caches[type][idx] = create_kmalloc_cache(
877 kmalloc_info[idx].name[type],
878 kmalloc_info[idx].size, flags, 0,
879 kmalloc_info[idx].size);
882 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for
883 * KMALLOC_NORMAL caches.
885 if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL))
886 kmalloc_caches[type][idx]->refcount = -1;
890 * Create the kmalloc array. Some of the regular kmalloc arrays
891 * may already have been created because they were needed to
892 * enable allocations for slab creation.
894 void __init create_kmalloc_caches(slab_flags_t flags)
897 enum kmalloc_cache_type type;
900 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined
902 for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) {
903 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
904 if (!kmalloc_caches[type][i])
905 new_kmalloc_cache(i, type, flags);
908 * Caches that are not of the two-to-the-power-of size.
909 * These have to be created immediately after the
910 * earlier power of two caches
912 if (KMALLOC_MIN_SIZE <= 32 && i == 6 &&
913 !kmalloc_caches[type][1])
914 new_kmalloc_cache(1, type, flags);
915 if (KMALLOC_MIN_SIZE <= 64 && i == 7 &&
916 !kmalloc_caches[type][2])
917 new_kmalloc_cache(2, type, flags);
921 /* Kmalloc array is now usable */
924 #ifdef CONFIG_ZONE_DMA
925 for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
926 struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];
929 kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(
930 kmalloc_info[i].name[KMALLOC_DMA],
931 kmalloc_info[i].size,
932 SLAB_CACHE_DMA | flags, 0,
933 kmalloc_info[i].size);
938 #endif /* !CONFIG_SLOB */
940 gfp_t kmalloc_fix_flags(gfp_t flags)
942 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
944 flags &= ~GFP_SLAB_BUG_MASK;
945 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
946 invalid_mask, &invalid_mask, flags, &flags);
953 * To avoid unnecessary overhead, we pass through large allocation requests
954 * directly to the page allocator. We use __GFP_COMP, because we will need to
955 * know the allocation order to free the pages properly in kfree.
957 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
962 if (unlikely(flags & GFP_SLAB_BUG_MASK))
963 flags = kmalloc_fix_flags(flags);
966 page = alloc_pages(flags, order);
968 ret = page_address(page);
969 mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B,
972 ret = kasan_kmalloc_large(ret, size, flags);
973 /* As ret might get tagged, call kmemleak hook after KASAN. */
974 kmemleak_alloc(ret, size, 1, flags);
977 EXPORT_SYMBOL(kmalloc_order);
979 #ifdef CONFIG_TRACING
980 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
982 void *ret = kmalloc_order(size, flags, order);
983 trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
986 EXPORT_SYMBOL(kmalloc_order_trace);
989 #ifdef CONFIG_SLAB_FREELIST_RANDOM
990 /* Randomize a generic freelist */
991 static void freelist_randomize(struct rnd_state *state, unsigned int *list,
997 for (i = 0; i < count; i++)
1000 /* Fisher-Yates shuffle */
1001 for (i = count - 1; i > 0; i--) {
1002 rand = prandom_u32_state(state);
1004 swap(list[i], list[rand]);
1008 /* Create a random sequence per cache */
1009 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
1012 struct rnd_state state;
1014 if (count < 2 || cachep->random_seq)
1017 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
1018 if (!cachep->random_seq)
1021 /* Get best entropy at this stage of boot */
1022 prandom_seed_state(&state, get_random_long());
1024 freelist_randomize(&state, cachep->random_seq, count);
1028 /* Destroy the per-cache random freelist sequence */
1029 void cache_random_seq_destroy(struct kmem_cache *cachep)
1031 kfree(cachep->random_seq);
1032 cachep->random_seq = NULL;
1034 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1036 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
1038 #define SLABINFO_RIGHTS (0600)
1040 #define SLABINFO_RIGHTS (0400)
1043 static void print_slabinfo_header(struct seq_file *m)
1046 * Output format version, so at least we can change it
1047 * without _too_ many complaints.
1049 #ifdef CONFIG_DEBUG_SLAB
1050 seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
1052 seq_puts(m, "slabinfo - version: 2.1\n");
1054 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1055 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1056 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1057 #ifdef CONFIG_DEBUG_SLAB
1058 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
1059 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
1064 void *slab_start(struct seq_file *m, loff_t *pos)
1066 mutex_lock(&slab_mutex);
1067 return seq_list_start(&slab_caches, *pos);
1070 void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1072 return seq_list_next(p, &slab_caches, pos);
1075 void slab_stop(struct seq_file *m, void *p)
1077 mutex_unlock(&slab_mutex);
1080 static void cache_show(struct kmem_cache *s, struct seq_file *m)
1082 struct slabinfo sinfo;
1084 memset(&sinfo, 0, sizeof(sinfo));
1085 get_slabinfo(s, &sinfo);
1087 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1088 s->name, sinfo.active_objs, sinfo.num_objs, s->size,
1089 sinfo.objects_per_slab, (1 << sinfo.cache_order));
1091 seq_printf(m, " : tunables %4u %4u %4u",
1092 sinfo.limit, sinfo.batchcount, sinfo.shared);
1093 seq_printf(m, " : slabdata %6lu %6lu %6lu",
1094 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1095 slabinfo_show_stats(m, s);
1099 static int slab_show(struct seq_file *m, void *p)
1101 struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1103 if (p == slab_caches.next)
1104 print_slabinfo_header(m);
1109 void dump_unreclaimable_slab(void)
1111 struct kmem_cache *s;
1112 struct slabinfo sinfo;
1115 * Here acquiring slab_mutex is risky since we don't prefer to get
1116 * sleep in oom path. But, without mutex hold, it may introduce a
1118 * Use mutex_trylock to protect the list traverse, dump nothing
1119 * without acquiring the mutex.
1121 if (!mutex_trylock(&slab_mutex)) {
1122 pr_warn("excessive unreclaimable slab but cannot dump stats\n");
1126 pr_info("Unreclaimable slab info:\n");
1127 pr_info("Name Used Total\n");
1129 list_for_each_entry(s, &slab_caches, list) {
1130 if (s->flags & SLAB_RECLAIM_ACCOUNT)
1133 get_slabinfo(s, &sinfo);
1135 if (sinfo.num_objs > 0)
1136 pr_info("%-17s %10luKB %10luKB\n", s->name,
1137 (sinfo.active_objs * s->size) / 1024,
1138 (sinfo.num_objs * s->size) / 1024);
1140 mutex_unlock(&slab_mutex);
1143 #if defined(CONFIG_MEMCG_KMEM)
1144 int memcg_slab_show(struct seq_file *m, void *p)
1148 * Please, take a look at tools/cgroup/slabinfo.py .
1155 * slabinfo_op - iterator that generates /proc/slabinfo
1164 * num-pages-per-slab
1165 * + further values on SMP and with statistics enabled
1167 static const struct seq_operations slabinfo_op = {
1168 .start = slab_start,
1174 static int slabinfo_open(struct inode *inode, struct file *file)
1176 return seq_open(file, &slabinfo_op);
1179 static const struct proc_ops slabinfo_proc_ops = {
1180 .proc_flags = PROC_ENTRY_PERMANENT,
1181 .proc_open = slabinfo_open,
1182 .proc_read = seq_read,
1183 .proc_write = slabinfo_write,
1184 .proc_lseek = seq_lseek,
1185 .proc_release = seq_release,
1188 static int __init slab_proc_init(void)
1190 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
1193 module_init(slab_proc_init);
1195 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
1197 static __always_inline void *__do_krealloc(const void *p, size_t new_size,
1203 /* Don't use instrumented ksize to allow precise KASAN poisoning. */
1204 if (likely(!ZERO_OR_NULL_PTR(p))) {
1205 if (!kasan_check_byte(p))
1207 ks = kfence_ksize(p) ?: __ksize(p);
1211 /* If the object still fits, repoison it precisely. */
1212 if (ks >= new_size) {
1213 p = kasan_krealloc((void *)p, new_size, flags);
1217 ret = kmalloc_track_caller(new_size, flags);
1219 /* Disable KASAN checks as the object's redzone is accessed. */
1220 kasan_disable_current();
1221 memcpy(ret, kasan_reset_tag(p), ks);
1222 kasan_enable_current();
1229 * krealloc - reallocate memory. The contents will remain unchanged.
1230 * @p: object to reallocate memory for.
1231 * @new_size: how many bytes of memory are required.
1232 * @flags: the type of memory to allocate.
1234 * The contents of the object pointed to are preserved up to the
1235 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored).
1236 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size
1237 * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
1239 * Return: pointer to the allocated memory or %NULL in case of error
1241 void *krealloc(const void *p, size_t new_size, gfp_t flags)
1245 if (unlikely(!new_size)) {
1247 return ZERO_SIZE_PTR;
1250 ret = __do_krealloc(p, new_size, flags);
1251 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
1256 EXPORT_SYMBOL(krealloc);
1259 * kfree_sensitive - Clear sensitive information in memory before freeing
1260 * @p: object to free memory of
1262 * The memory of the object @p points to is zeroed before freed.
1263 * If @p is %NULL, kfree_sensitive() does nothing.
1265 * Note: this function zeroes the whole allocated buffer which can be a good
1266 * deal bigger than the requested buffer size passed to kmalloc(). So be
1267 * careful when using this function in performance sensitive code.
1269 void kfree_sensitive(const void *p)
1272 void *mem = (void *)p;
1276 memzero_explicit(mem, ks);
1279 EXPORT_SYMBOL(kfree_sensitive);
1282 * ksize - get the actual amount of memory allocated for a given object
1283 * @objp: Pointer to the object
1285 * kmalloc may internally round up allocations and return more memory
1286 * than requested. ksize() can be used to determine the actual amount of
1287 * memory allocated. The caller may use this additional memory, even though
1288 * a smaller amount of memory was initially specified with the kmalloc call.
1289 * The caller must guarantee that objp points to a valid object previously
1290 * allocated with either kmalloc() or kmem_cache_alloc(). The object
1291 * must not be freed during the duration of the call.
1293 * Return: size of the actual memory used by @objp in bytes
1295 size_t ksize(const void *objp)
1300 * We need to first check that the pointer to the object is valid, and
1301 * only then unpoison the memory. The report printed from ksize() is
1302 * more useful, then when it's printed later when the behaviour could
1303 * be undefined due to a potential use-after-free or double-free.
1305 * We use kasan_check_byte(), which is supported for the hardware
1306 * tag-based KASAN mode, unlike kasan_check_read/write().
1308 * If the pointed to memory is invalid, we return 0 to avoid users of
1309 * ksize() writing to and potentially corrupting the memory region.
1311 * We want to perform the check before __ksize(), to avoid potentially
1312 * crashing in __ksize() due to accessing invalid metadata.
1314 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
1317 size = kfence_ksize(objp) ?: __ksize(objp);
1319 * We assume that ksize callers could use whole allocated area,
1320 * so we need to unpoison this area.
1322 kasan_unpoison_range(objp, size);
1325 EXPORT_SYMBOL(ksize);
1327 /* Tracepoints definitions. */
1328 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1329 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1330 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
1331 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
1332 EXPORT_TRACEPOINT_SYMBOL(kfree);
1333 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1335 int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
1337 if (__should_failslab(s, gfpflags))
1341 ALLOW_ERROR_INJECTION(should_failslab, ERRNO);