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
);
572 * kmem_dump_obj - Print available slab provenance information
573 * @object: slab object for which to find provenance information.
575 * This function uses pr_cont(), so that the caller is expected to have
576 * printed out whatever preamble is appropriate. The provenance information
577 * depends on the type of object and on how much debugging is enabled.
578 * For a slab-cache object, the fact that it is a slab object is printed,
579 * and, if available, the slab name, return address, and stack trace from
580 * the allocation and last free path of that object.
582 * This function will splat if passed a pointer to a non-slab object.
583 * If you are not sure what type of object you have, you should instead
584 * use mem_dump_obj().
586 void kmem_dump_obj(void *object
)
588 char *cp
= IS_ENABLED(CONFIG_MMU
) ? "" : "/vmalloc";
591 unsigned long ptroffset
;
592 struct kmem_obj_info kp
= { };
594 if (WARN_ON_ONCE(!virt_addr_valid(object
)))
596 page
= virt_to_head_page(object
);
597 if (WARN_ON_ONCE(!PageSlab(page
))) {
598 pr_cont(" non-slab memory.\n");
601 kmem_obj_info(&kp
, object
, page
);
602 if (kp
.kp_slab_cache
)
603 pr_cont(" slab%s %s", cp
, kp
.kp_slab_cache
->name
);
605 pr_cont(" slab%s", cp
);
607 pr_cont(" start %px", kp
.kp_objp
);
608 if (kp
.kp_data_offset
)
609 pr_cont(" data offset %lu", kp
.kp_data_offset
);
611 ptroffset
= ((char *)object
- (char *)kp
.kp_objp
) - kp
.kp_data_offset
;
612 pr_cont(" pointer offset %lu", ptroffset
);
614 if (kp
.kp_slab_cache
&& kp
.kp_slab_cache
->usersize
)
615 pr_cont(" size %u", kp
.kp_slab_cache
->usersize
);
617 pr_cont(" allocated at %pS\n", kp
.kp_ret
);
620 for (i
= 0; i
< ARRAY_SIZE(kp
.kp_stack
); i
++) {
623 pr_info(" %pS\n", kp
.kp_stack
[i
]);
626 if (kp
.kp_free_stack
[0])
627 pr_cont(" Free path:\n");
629 for (i
= 0; i
< ARRAY_SIZE(kp
.kp_free_stack
); i
++) {
630 if (!kp
.kp_free_stack
[i
])
632 pr_info(" %pS\n", kp
.kp_free_stack
[i
]);
636 EXPORT_SYMBOL_GPL(kmem_dump_obj
);
640 /* Create a cache during boot when no slab services are available yet */
641 void __init
create_boot_cache(struct kmem_cache
*s
, const char *name
,
642 unsigned int size
, slab_flags_t flags
,
643 unsigned int useroffset
, unsigned int usersize
)
646 unsigned int align
= ARCH_KMALLOC_MINALIGN
;
649 s
->size
= s
->object_size
= size
;
652 * For power of two sizes, guarantee natural alignment for kmalloc
653 * caches, regardless of SL*B debugging options.
655 if (is_power_of_2(size
))
656 align
= max(align
, size
);
657 s
->align
= calculate_alignment(flags
, align
, size
);
659 s
->useroffset
= useroffset
;
660 s
->usersize
= usersize
;
662 err
= __kmem_cache_create(s
, flags
);
665 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
668 s
->refcount
= -1; /* Exempt from merging for now */
671 struct kmem_cache
*__init
create_kmalloc_cache(const char *name
,
672 unsigned int size
, slab_flags_t flags
,
673 unsigned int useroffset
, unsigned int usersize
)
675 struct kmem_cache
*s
= kmem_cache_zalloc(kmem_cache
, GFP_NOWAIT
);
678 panic("Out of memory when creating slab %s\n", name
);
680 create_boot_cache(s
, name
, size
, flags
, useroffset
, usersize
);
681 kasan_cache_create_kmalloc(s
);
682 list_add(&s
->list
, &slab_caches
);
688 kmalloc_caches
[NR_KMALLOC_TYPES
][KMALLOC_SHIFT_HIGH
+ 1] __ro_after_init
=
689 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ };
690 EXPORT_SYMBOL(kmalloc_caches
);
693 * Conversion table for small slabs sizes / 8 to the index in the
694 * kmalloc array. This is necessary for slabs < 192 since we have non power
695 * of two cache sizes there. The size of larger slabs can be determined using
698 static u8 size_index
[24] __ro_after_init
= {
725 static inline unsigned int size_index_elem(unsigned int bytes
)
727 return (bytes
- 1) / 8;
731 * Find the kmem_cache structure that serves a given size of
734 struct kmem_cache
*kmalloc_slab(size_t size
, gfp_t flags
)
740 return ZERO_SIZE_PTR
;
742 index
= size_index
[size_index_elem(size
)];
744 if (WARN_ON_ONCE(size
> KMALLOC_MAX_CACHE_SIZE
))
746 index
= fls(size
- 1);
749 return kmalloc_caches
[kmalloc_type(flags
)][index
];
752 #ifdef CONFIG_ZONE_DMA
753 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
755 #define KMALLOC_DMA_NAME(sz)
758 #ifdef CONFIG_MEMCG_KMEM
759 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
761 #define KMALLOC_CGROUP_NAME(sz)
764 #define INIT_KMALLOC_INFO(__size, __short_size) \
766 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \
767 .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \
768 KMALLOC_CGROUP_NAME(__short_size) \
769 KMALLOC_DMA_NAME(__short_size) \
774 * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
775 * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is
778 const struct kmalloc_info_struct kmalloc_info
[] __initconst
= {
779 INIT_KMALLOC_INFO(0, 0),
780 INIT_KMALLOC_INFO(96, 96),
781 INIT_KMALLOC_INFO(192, 192),
782 INIT_KMALLOC_INFO(8, 8),
783 INIT_KMALLOC_INFO(16, 16),
784 INIT_KMALLOC_INFO(32, 32),
785 INIT_KMALLOC_INFO(64, 64),
786 INIT_KMALLOC_INFO(128, 128),
787 INIT_KMALLOC_INFO(256, 256),
788 INIT_KMALLOC_INFO(512, 512),
789 INIT_KMALLOC_INFO(1024, 1k
),
790 INIT_KMALLOC_INFO(2048, 2k
),
791 INIT_KMALLOC_INFO(4096, 4k
),
792 INIT_KMALLOC_INFO(8192, 8k
),
793 INIT_KMALLOC_INFO(16384, 16k
),
794 INIT_KMALLOC_INFO(32768, 32k
),
795 INIT_KMALLOC_INFO(65536, 64k
),
796 INIT_KMALLOC_INFO(131072, 128k
),
797 INIT_KMALLOC_INFO(262144, 256k
),
798 INIT_KMALLOC_INFO(524288, 512k
),
799 INIT_KMALLOC_INFO(1048576, 1M
),
800 INIT_KMALLOC_INFO(2097152, 2M
),
801 INIT_KMALLOC_INFO(4194304, 4M
),
802 INIT_KMALLOC_INFO(8388608, 8M
),
803 INIT_KMALLOC_INFO(16777216, 16M
),
804 INIT_KMALLOC_INFO(33554432, 32M
)
808 * Patch up the size_index table if we have strange large alignment
809 * requirements for the kmalloc array. This is only the case for
810 * MIPS it seems. The standard arches will not generate any code here.
812 * Largest permitted alignment is 256 bytes due to the way we
813 * handle the index determination for the smaller caches.
815 * Make sure that nothing crazy happens if someone starts tinkering
816 * around with ARCH_KMALLOC_MINALIGN
818 void __init
setup_kmalloc_cache_index_table(void)
822 BUILD_BUG_ON(KMALLOC_MIN_SIZE
> 256 ||
823 (KMALLOC_MIN_SIZE
& (KMALLOC_MIN_SIZE
- 1)));
825 for (i
= 8; i
< KMALLOC_MIN_SIZE
; i
+= 8) {
826 unsigned int elem
= size_index_elem(i
);
828 if (elem
>= ARRAY_SIZE(size_index
))
830 size_index
[elem
] = KMALLOC_SHIFT_LOW
;
833 if (KMALLOC_MIN_SIZE
>= 64) {
835 * The 96 byte size cache is not used if the alignment
838 for (i
= 64 + 8; i
<= 96; i
+= 8)
839 size_index
[size_index_elem(i
)] = 7;
843 if (KMALLOC_MIN_SIZE
>= 128) {
845 * The 192 byte sized cache is not used if the alignment
846 * is 128 byte. Redirect kmalloc to use the 256 byte cache
849 for (i
= 128 + 8; i
<= 192; i
+= 8)
850 size_index
[size_index_elem(i
)] = 8;
855 new_kmalloc_cache(int idx
, enum kmalloc_cache_type type
, slab_flags_t flags
)
857 if (type
== KMALLOC_RECLAIM
) {
858 flags
|= SLAB_RECLAIM_ACCOUNT
;
859 } else if (IS_ENABLED(CONFIG_MEMCG_KMEM
) && (type
== KMALLOC_CGROUP
)) {
860 if (cgroup_memory_nokmem
) {
861 kmalloc_caches
[type
][idx
] = kmalloc_caches
[KMALLOC_NORMAL
][idx
];
864 flags
|= SLAB_ACCOUNT
;
867 kmalloc_caches
[type
][idx
] = create_kmalloc_cache(
868 kmalloc_info
[idx
].name
[type
],
869 kmalloc_info
[idx
].size
, flags
, 0,
870 kmalloc_info
[idx
].size
);
873 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for
874 * KMALLOC_NORMAL caches.
876 if (IS_ENABLED(CONFIG_MEMCG_KMEM
) && (type
== KMALLOC_NORMAL
))
877 kmalloc_caches
[type
][idx
]->refcount
= -1;
881 * Create the kmalloc array. Some of the regular kmalloc arrays
882 * may already have been created because they were needed to
883 * enable allocations for slab creation.
885 void __init
create_kmalloc_caches(slab_flags_t flags
)
888 enum kmalloc_cache_type type
;
891 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined
893 for (type
= KMALLOC_NORMAL
; type
<= KMALLOC_RECLAIM
; type
++) {
894 for (i
= KMALLOC_SHIFT_LOW
; i
<= KMALLOC_SHIFT_HIGH
; i
++) {
895 if (!kmalloc_caches
[type
][i
])
896 new_kmalloc_cache(i
, type
, flags
);
899 * Caches that are not of the two-to-the-power-of size.
900 * These have to be created immediately after the
901 * earlier power of two caches
903 if (KMALLOC_MIN_SIZE
<= 32 && i
== 6 &&
904 !kmalloc_caches
[type
][1])
905 new_kmalloc_cache(1, type
, flags
);
906 if (KMALLOC_MIN_SIZE
<= 64 && i
== 7 &&
907 !kmalloc_caches
[type
][2])
908 new_kmalloc_cache(2, type
, flags
);
912 /* Kmalloc array is now usable */
915 #ifdef CONFIG_ZONE_DMA
916 for (i
= 0; i
<= KMALLOC_SHIFT_HIGH
; i
++) {
917 struct kmem_cache
*s
= kmalloc_caches
[KMALLOC_NORMAL
][i
];
920 kmalloc_caches
[KMALLOC_DMA
][i
] = create_kmalloc_cache(
921 kmalloc_info
[i
].name
[KMALLOC_DMA
],
922 kmalloc_info
[i
].size
,
923 SLAB_CACHE_DMA
| flags
, 0,
924 kmalloc_info
[i
].size
);
929 #endif /* !CONFIG_SLOB */
931 gfp_t
kmalloc_fix_flags(gfp_t flags
)
933 gfp_t invalid_mask
= flags
& GFP_SLAB_BUG_MASK
;
935 flags
&= ~GFP_SLAB_BUG_MASK
;
936 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
937 invalid_mask
, &invalid_mask
, flags
, &flags
);
944 * To avoid unnecessary overhead, we pass through large allocation requests
945 * directly to the page allocator. We use __GFP_COMP, because we will need to
946 * know the allocation order to free the pages properly in kfree.
948 void *kmalloc_order(size_t size
, gfp_t flags
, unsigned int order
)
953 if (unlikely(flags
& GFP_SLAB_BUG_MASK
))
954 flags
= kmalloc_fix_flags(flags
);
957 page
= alloc_pages(flags
, order
);
959 ret
= page_address(page
);
960 mod_lruvec_page_state(page
, NR_SLAB_UNRECLAIMABLE_B
,
963 ret
= kasan_kmalloc_large(ret
, size
, flags
);
964 /* As ret might get tagged, call kmemleak hook after KASAN. */
965 kmemleak_alloc(ret
, size
, 1, flags
);
968 EXPORT_SYMBOL(kmalloc_order
);
970 #ifdef CONFIG_TRACING
971 void *kmalloc_order_trace(size_t size
, gfp_t flags
, unsigned int order
)
973 void *ret
= kmalloc_order(size
, flags
, order
);
974 trace_kmalloc(_RET_IP_
, ret
, size
, PAGE_SIZE
<< order
, flags
);
977 EXPORT_SYMBOL(kmalloc_order_trace
);
980 #ifdef CONFIG_SLAB_FREELIST_RANDOM
981 /* Randomize a generic freelist */
982 static void freelist_randomize(struct rnd_state
*state
, unsigned int *list
,
988 for (i
= 0; i
< count
; i
++)
991 /* Fisher-Yates shuffle */
992 for (i
= count
- 1; i
> 0; i
--) {
993 rand
= prandom_u32_state(state
);
995 swap(list
[i
], list
[rand
]);
999 /* Create a random sequence per cache */
1000 int cache_random_seq_create(struct kmem_cache
*cachep
, unsigned int count
,
1003 struct rnd_state state
;
1005 if (count
< 2 || cachep
->random_seq
)
1008 cachep
->random_seq
= kcalloc(count
, sizeof(unsigned int), gfp
);
1009 if (!cachep
->random_seq
)
1012 /* Get best entropy at this stage of boot */
1013 prandom_seed_state(&state
, get_random_long());
1015 freelist_randomize(&state
, cachep
->random_seq
, count
);
1019 /* Destroy the per-cache random freelist sequence */
1020 void cache_random_seq_destroy(struct kmem_cache
*cachep
)
1022 kfree(cachep
->random_seq
);
1023 cachep
->random_seq
= NULL
;
1025 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1027 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
1029 #define SLABINFO_RIGHTS (0600)
1031 #define SLABINFO_RIGHTS (0400)
1034 static void print_slabinfo_header(struct seq_file
*m
)
1037 * Output format version, so at least we can change it
1038 * without _too_ many complaints.
1040 #ifdef CONFIG_DEBUG_SLAB
1041 seq_puts(m
, "slabinfo - version: 2.1 (statistics)\n");
1043 seq_puts(m
, "slabinfo - version: 2.1\n");
1045 seq_puts(m
, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1046 seq_puts(m
, " : tunables <limit> <batchcount> <sharedfactor>");
1047 seq_puts(m
, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1048 #ifdef CONFIG_DEBUG_SLAB
1049 seq_puts(m
, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
1050 seq_puts(m
, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
1055 void *slab_start(struct seq_file
*m
, loff_t
*pos
)
1057 mutex_lock(&slab_mutex
);
1058 return seq_list_start(&slab_caches
, *pos
);
1061 void *slab_next(struct seq_file
*m
, void *p
, loff_t
*pos
)
1063 return seq_list_next(p
, &slab_caches
, pos
);
1066 void slab_stop(struct seq_file
*m
, void *p
)
1068 mutex_unlock(&slab_mutex
);
1071 static void cache_show(struct kmem_cache
*s
, struct seq_file
*m
)
1073 struct slabinfo sinfo
;
1075 memset(&sinfo
, 0, sizeof(sinfo
));
1076 get_slabinfo(s
, &sinfo
);
1078 seq_printf(m
, "%-17s %6lu %6lu %6u %4u %4d",
1079 s
->name
, sinfo
.active_objs
, sinfo
.num_objs
, s
->size
,
1080 sinfo
.objects_per_slab
, (1 << sinfo
.cache_order
));
1082 seq_printf(m
, " : tunables %4u %4u %4u",
1083 sinfo
.limit
, sinfo
.batchcount
, sinfo
.shared
);
1084 seq_printf(m
, " : slabdata %6lu %6lu %6lu",
1085 sinfo
.active_slabs
, sinfo
.num_slabs
, sinfo
.shared_avail
);
1086 slabinfo_show_stats(m
, s
);
1090 static int slab_show(struct seq_file
*m
, void *p
)
1092 struct kmem_cache
*s
= list_entry(p
, struct kmem_cache
, list
);
1094 if (p
== slab_caches
.next
)
1095 print_slabinfo_header(m
);
1100 void dump_unreclaimable_slab(void)
1102 struct kmem_cache
*s
;
1103 struct slabinfo sinfo
;
1106 * Here acquiring slab_mutex is risky since we don't prefer to get
1107 * sleep in oom path. But, without mutex hold, it may introduce a
1109 * Use mutex_trylock to protect the list traverse, dump nothing
1110 * without acquiring the mutex.
1112 if (!mutex_trylock(&slab_mutex
)) {
1113 pr_warn("excessive unreclaimable slab but cannot dump stats\n");
1117 pr_info("Unreclaimable slab info:\n");
1118 pr_info("Name Used Total\n");
1120 list_for_each_entry(s
, &slab_caches
, list
) {
1121 if (s
->flags
& SLAB_RECLAIM_ACCOUNT
)
1124 get_slabinfo(s
, &sinfo
);
1126 if (sinfo
.num_objs
> 0)
1127 pr_info("%-17s %10luKB %10luKB\n", s
->name
,
1128 (sinfo
.active_objs
* s
->size
) / 1024,
1129 (sinfo
.num_objs
* s
->size
) / 1024);
1131 mutex_unlock(&slab_mutex
);
1134 #if defined(CONFIG_MEMCG_KMEM)
1135 int memcg_slab_show(struct seq_file
*m
, void *p
)
1139 * Please, take a look at tools/cgroup/slabinfo.py .
1146 * slabinfo_op - iterator that generates /proc/slabinfo
1155 * num-pages-per-slab
1156 * + further values on SMP and with statistics enabled
1158 static const struct seq_operations slabinfo_op
= {
1159 .start
= slab_start
,
1165 static int slabinfo_open(struct inode
*inode
, struct file
*file
)
1167 return seq_open(file
, &slabinfo_op
);
1170 static const struct proc_ops slabinfo_proc_ops
= {
1171 .proc_flags
= PROC_ENTRY_PERMANENT
,
1172 .proc_open
= slabinfo_open
,
1173 .proc_read
= seq_read
,
1174 .proc_write
= slabinfo_write
,
1175 .proc_lseek
= seq_lseek
,
1176 .proc_release
= seq_release
,
1179 static int __init
slab_proc_init(void)
1181 proc_create("slabinfo", SLABINFO_RIGHTS
, NULL
, &slabinfo_proc_ops
);
1184 module_init(slab_proc_init
);
1186 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
1188 static __always_inline
void *__do_krealloc(const void *p
, size_t new_size
,
1194 /* Don't use instrumented ksize to allow precise KASAN poisoning. */
1195 if (likely(!ZERO_OR_NULL_PTR(p
))) {
1196 if (!kasan_check_byte(p
))
1198 ks
= kfence_ksize(p
) ?: __ksize(p
);
1202 /* If the object still fits, repoison it precisely. */
1203 if (ks
>= new_size
) {
1204 p
= kasan_krealloc((void *)p
, new_size
, flags
);
1208 ret
= kmalloc_track_caller(new_size
, flags
);
1210 /* Disable KASAN checks as the object's redzone is accessed. */
1211 kasan_disable_current();
1212 memcpy(ret
, kasan_reset_tag(p
), ks
);
1213 kasan_enable_current();
1220 * krealloc - reallocate memory. The contents will remain unchanged.
1221 * @p: object to reallocate memory for.
1222 * @new_size: how many bytes of memory are required.
1223 * @flags: the type of memory to allocate.
1225 * The contents of the object pointed to are preserved up to the
1226 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored).
1227 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size
1228 * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
1230 * Return: pointer to the allocated memory or %NULL in case of error
1232 void *krealloc(const void *p
, size_t new_size
, gfp_t flags
)
1236 if (unlikely(!new_size
)) {
1238 return ZERO_SIZE_PTR
;
1241 ret
= __do_krealloc(p
, new_size
, flags
);
1242 if (ret
&& kasan_reset_tag(p
) != kasan_reset_tag(ret
))
1247 EXPORT_SYMBOL(krealloc
);
1250 * kfree_sensitive - Clear sensitive information in memory before freeing
1251 * @p: object to free memory of
1253 * The memory of the object @p points to is zeroed before freed.
1254 * If @p is %NULL, kfree_sensitive() does nothing.
1256 * Note: this function zeroes the whole allocated buffer which can be a good
1257 * deal bigger than the requested buffer size passed to kmalloc(). So be
1258 * careful when using this function in performance sensitive code.
1260 void kfree_sensitive(const void *p
)
1263 void *mem
= (void *)p
;
1267 memzero_explicit(mem
, ks
);
1270 EXPORT_SYMBOL(kfree_sensitive
);
1273 * ksize - get the actual amount of memory allocated for a given object
1274 * @objp: Pointer to the object
1276 * kmalloc may internally round up allocations and return more memory
1277 * than requested. ksize() can be used to determine the actual amount of
1278 * memory allocated. The caller may use this additional memory, even though
1279 * a smaller amount of memory was initially specified with the kmalloc call.
1280 * The caller must guarantee that objp points to a valid object previously
1281 * allocated with either kmalloc() or kmem_cache_alloc(). The object
1282 * must not be freed during the duration of the call.
1284 * Return: size of the actual memory used by @objp in bytes
1286 size_t ksize(const void *objp
)
1291 * We need to first check that the pointer to the object is valid, and
1292 * only then unpoison the memory. The report printed from ksize() is
1293 * more useful, then when it's printed later when the behaviour could
1294 * be undefined due to a potential use-after-free or double-free.
1296 * We use kasan_check_byte(), which is supported for the hardware
1297 * tag-based KASAN mode, unlike kasan_check_read/write().
1299 * If the pointed to memory is invalid, we return 0 to avoid users of
1300 * ksize() writing to and potentially corrupting the memory region.
1302 * We want to perform the check before __ksize(), to avoid potentially
1303 * crashing in __ksize() due to accessing invalid metadata.
1305 if (unlikely(ZERO_OR_NULL_PTR(objp
)) || !kasan_check_byte(objp
))
1308 size
= kfence_ksize(objp
) ?: __ksize(objp
);
1310 * We assume that ksize callers could use whole allocated area,
1311 * so we need to unpoison this area.
1313 kasan_unpoison_range(objp
, size
);
1316 EXPORT_SYMBOL(ksize
);
1318 /* Tracepoints definitions. */
1319 EXPORT_TRACEPOINT_SYMBOL(kmalloc
);
1320 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc
);
1321 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node
);
1322 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node
);
1323 EXPORT_TRACEPOINT_SYMBOL(kfree
);
1324 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free
);
1326 int should_failslab(struct kmem_cache
*s
, gfp_t gfpflags
)
1328 if (__should_failslab(s
, gfpflags
))
1332 ALLOW_ERROR_INJECTION(should_failslab
, ERRNO
);