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TOMOYO Linux Cross Reference
Linux/include/linux/slab.h

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 /*
  3  * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
  4  *
  5  * (C) SGI 2006, Christoph Lameter
  6  *      Cleaned up and restructured to ease the addition of alternative
  7  *      implementations of SLAB allocators.
  8  * (C) Linux Foundation 2008-2013
  9  *      Unified interface for all slab allocators
 10  */
 11 
 12 #ifndef _LINUX_SLAB_H
 13 #define _LINUX_SLAB_H
 14 
 15 #include <linux/gfp.h>
 16 #include <linux/overflow.h>
 17 #include <linux/types.h>
 18 #include <linux/workqueue.h>
 19 #include <linux/percpu-refcount.h>
 20 
 21 
 22 /*
 23  * Flags to pass to kmem_cache_create().
 24  * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
 25  */
 26 /* DEBUG: Perform (expensive) checks on alloc/free */
 27 #define SLAB_CONSISTENCY_CHECKS ((slab_flags_t __force)0x00000100U)
 28 /* DEBUG: Red zone objs in a cache */
 29 #define SLAB_RED_ZONE           ((slab_flags_t __force)0x00000400U)
 30 /* DEBUG: Poison objects */
 31 #define SLAB_POISON             ((slab_flags_t __force)0x00000800U)
 32 /* Align objs on cache lines */
 33 #define SLAB_HWCACHE_ALIGN      ((slab_flags_t __force)0x00002000U)
 34 /* Use GFP_DMA memory */
 35 #define SLAB_CACHE_DMA          ((slab_flags_t __force)0x00004000U)
 36 /* Use GFP_DMA32 memory */
 37 #define SLAB_CACHE_DMA32        ((slab_flags_t __force)0x00008000U)
 38 /* DEBUG: Store the last owner for bug hunting */
 39 #define SLAB_STORE_USER         ((slab_flags_t __force)0x00010000U)
 40 /* Panic if kmem_cache_create() fails */
 41 #define SLAB_PANIC              ((slab_flags_t __force)0x00040000U)
 42 /*
 43  * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
 44  *
 45  * This delays freeing the SLAB page by a grace period, it does _NOT_
 46  * delay object freeing. This means that if you do kmem_cache_free()
 47  * that memory location is free to be reused at any time. Thus it may
 48  * be possible to see another object there in the same RCU grace period.
 49  *
 50  * This feature only ensures the memory location backing the object
 51  * stays valid, the trick to using this is relying on an independent
 52  * object validation pass. Something like:
 53  *
 54  *  rcu_read_lock()
 55  * again:
 56  *  obj = lockless_lookup(key);
 57  *  if (obj) {
 58  *    if (!try_get_ref(obj)) // might fail for free objects
 59  *      goto again;
 60  *
 61  *    if (obj->key != key) { // not the object we expected
 62  *      put_ref(obj);
 63  *      goto again;
 64  *    }
 65  *  }
 66  *  rcu_read_unlock();
 67  *
 68  * This is useful if we need to approach a kernel structure obliquely,
 69  * from its address obtained without the usual locking. We can lock
 70  * the structure to stabilize it and check it's still at the given address,
 71  * only if we can be sure that the memory has not been meanwhile reused
 72  * for some other kind of object (which our subsystem's lock might corrupt).
 73  *
 74  * rcu_read_lock before reading the address, then rcu_read_unlock after
 75  * taking the spinlock within the structure expected at that address.
 76  *
 77  * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
 78  */
 79 /* Defer freeing slabs to RCU */
 80 #define SLAB_TYPESAFE_BY_RCU    ((slab_flags_t __force)0x00080000U)
 81 /* Spread some memory over cpuset */
 82 #define SLAB_MEM_SPREAD         ((slab_flags_t __force)0x00100000U)
 83 /* Trace allocations and frees */
 84 #define SLAB_TRACE              ((slab_flags_t __force)0x00200000U)
 85 
 86 /* Flag to prevent checks on free */
 87 #ifdef CONFIG_DEBUG_OBJECTS
 88 # define SLAB_DEBUG_OBJECTS     ((slab_flags_t __force)0x00400000U)
 89 #else
 90 # define SLAB_DEBUG_OBJECTS     0
 91 #endif
 92 
 93 /* Avoid kmemleak tracing */
 94 #define SLAB_NOLEAKTRACE        ((slab_flags_t __force)0x00800000U)
 95 
 96 /* Fault injection mark */
 97 #ifdef CONFIG_FAILSLAB
 98 # define SLAB_FAILSLAB          ((slab_flags_t __force)0x02000000U)
 99 #else
100 # define SLAB_FAILSLAB          0
101 #endif
102 /* Account to memcg */
103 #ifdef CONFIG_MEMCG_KMEM
104 # define SLAB_ACCOUNT           ((slab_flags_t __force)0x04000000U)
105 #else
106 # define SLAB_ACCOUNT           0
107 #endif
108 
109 #ifdef CONFIG_KASAN
110 #define SLAB_KASAN              ((slab_flags_t __force)0x08000000U)
111 #else
112 #define SLAB_KASAN              0
113 #endif
114 
115 /* The following flags affect the page allocator grouping pages by mobility */
116 /* Objects are reclaimable */
117 #define SLAB_RECLAIM_ACCOUNT    ((slab_flags_t __force)0x00020000U)
118 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
119 
120 /* Slab deactivation flag */
121 #define SLAB_DEACTIVATED        ((slab_flags_t __force)0x10000000U)
122 
123 /*
124  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
125  *
126  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
127  *
128  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
129  * Both make kfree a no-op.
130  */
131 #define ZERO_SIZE_PTR ((void *)16)
132 
133 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
134                                 (unsigned long)ZERO_SIZE_PTR)
135 
136 #include <linux/kasan.h>
137 
138 struct mem_cgroup;
139 /*
140  * struct kmem_cache related prototypes
141  */
142 void __init kmem_cache_init(void);
143 bool slab_is_available(void);
144 
145 extern bool usercopy_fallback;
146 
147 struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
148                         unsigned int align, slab_flags_t flags,
149                         void (*ctor)(void *));
150 struct kmem_cache *kmem_cache_create_usercopy(const char *name,
151                         unsigned int size, unsigned int align,
152                         slab_flags_t flags,
153                         unsigned int useroffset, unsigned int usersize,
154                         void (*ctor)(void *));
155 void kmem_cache_destroy(struct kmem_cache *);
156 int kmem_cache_shrink(struct kmem_cache *);
157 
158 void memcg_create_kmem_cache(struct mem_cgroup *, struct kmem_cache *);
159 void memcg_deactivate_kmem_caches(struct mem_cgroup *, struct mem_cgroup *);
160 
161 /*
162  * Please use this macro to create slab caches. Simply specify the
163  * name of the structure and maybe some flags that are listed above.
164  *
165  * The alignment of the struct determines object alignment. If you
166  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
167  * then the objects will be properly aligned in SMP configurations.
168  */
169 #define KMEM_CACHE(__struct, __flags)                                   \
170                 kmem_cache_create(#__struct, sizeof(struct __struct),   \
171                         __alignof__(struct __struct), (__flags), NULL)
172 
173 /*
174  * To whitelist a single field for copying to/from usercopy, use this
175  * macro instead for KMEM_CACHE() above.
176  */
177 #define KMEM_CACHE_USERCOPY(__struct, __flags, __field)                 \
178                 kmem_cache_create_usercopy(#__struct,                   \
179                         sizeof(struct __struct),                        \
180                         __alignof__(struct __struct), (__flags),        \
181                         offsetof(struct __struct, __field),             \
182                         sizeof_field(struct __struct, __field), NULL)
183 
184 /*
185  * Common kmalloc functions provided by all allocators
186  */
187 void * __must_check krealloc(const void *, size_t, gfp_t);
188 void kfree(const void *);
189 void kzfree(const void *);
190 size_t __ksize(const void *);
191 size_t ksize(const void *);
192 
193 #ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR
194 void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
195                         bool to_user);
196 #else
197 static inline void __check_heap_object(const void *ptr, unsigned long n,
198                                        struct page *page, bool to_user) { }
199 #endif
200 
201 /*
202  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
203  * alignment larger than the alignment of a 64-bit integer.
204  * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
205  */
206 #if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
207 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
208 #define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
209 #define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
210 #else
211 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
212 #endif
213 
214 /*
215  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
216  * Intended for arches that get misalignment faults even for 64 bit integer
217  * aligned buffers.
218  */
219 #ifndef ARCH_SLAB_MINALIGN
220 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
221 #endif
222 
223 /*
224  * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned
225  * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN
226  * aligned pointers.
227  */
228 #define __assume_kmalloc_alignment __assume_aligned(ARCH_KMALLOC_MINALIGN)
229 #define __assume_slab_alignment __assume_aligned(ARCH_SLAB_MINALIGN)
230 #define __assume_page_alignment __assume_aligned(PAGE_SIZE)
231 
232 /*
233  * Kmalloc array related definitions
234  */
235 
236 #ifdef CONFIG_SLAB
237 /*
238  * The largest kmalloc size supported by the SLAB allocators is
239  * 32 megabyte (2^25) or the maximum allocatable page order if that is
240  * less than 32 MB.
241  *
242  * WARNING: Its not easy to increase this value since the allocators have
243  * to do various tricks to work around compiler limitations in order to
244  * ensure proper constant folding.
245  */
246 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
247                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
248 #define KMALLOC_SHIFT_MAX       KMALLOC_SHIFT_HIGH
249 #ifndef KMALLOC_SHIFT_LOW
250 #define KMALLOC_SHIFT_LOW       5
251 #endif
252 #endif
253 
254 #ifdef CONFIG_SLUB
255 /*
256  * SLUB directly allocates requests fitting in to an order-1 page
257  * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
258  */
259 #define KMALLOC_SHIFT_HIGH      (PAGE_SHIFT + 1)
260 #define KMALLOC_SHIFT_MAX       (MAX_ORDER + PAGE_SHIFT - 1)
261 #ifndef KMALLOC_SHIFT_LOW
262 #define KMALLOC_SHIFT_LOW       3
263 #endif
264 #endif
265 
266 #ifdef CONFIG_SLOB
267 /*
268  * SLOB passes all requests larger than one page to the page allocator.
269  * No kmalloc array is necessary since objects of different sizes can
270  * be allocated from the same page.
271  */
272 #define KMALLOC_SHIFT_HIGH      PAGE_SHIFT
273 #define KMALLOC_SHIFT_MAX       (MAX_ORDER + PAGE_SHIFT - 1)
274 #ifndef KMALLOC_SHIFT_LOW
275 #define KMALLOC_SHIFT_LOW       3
276 #endif
277 #endif
278 
279 /* Maximum allocatable size */
280 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_MAX)
281 /* Maximum size for which we actually use a slab cache */
282 #define KMALLOC_MAX_CACHE_SIZE  (1UL << KMALLOC_SHIFT_HIGH)
283 /* Maximum order allocatable via the slab allocagtor */
284 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
285 
286 /*
287  * Kmalloc subsystem.
288  */
289 #ifndef KMALLOC_MIN_SIZE
290 #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
291 #endif
292 
293 /*
294  * This restriction comes from byte sized index implementation.
295  * Page size is normally 2^12 bytes and, in this case, if we want to use
296  * byte sized index which can represent 2^8 entries, the size of the object
297  * should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
298  * If minimum size of kmalloc is less than 16, we use it as minimum object
299  * size and give up to use byte sized index.
300  */
301 #define SLAB_OBJ_MIN_SIZE      (KMALLOC_MIN_SIZE < 16 ? \
302                                (KMALLOC_MIN_SIZE) : 16)
303 
304 /*
305  * Whenever changing this, take care of that kmalloc_type() and
306  * create_kmalloc_caches() still work as intended.
307  */
308 enum kmalloc_cache_type {
309         KMALLOC_NORMAL = 0,
310         KMALLOC_RECLAIM,
311 #ifdef CONFIG_ZONE_DMA
312         KMALLOC_DMA,
313 #endif
314         NR_KMALLOC_TYPES
315 };
316 
317 #ifndef CONFIG_SLOB
318 extern struct kmem_cache *
319 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
320 
321 static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
322 {
323 #ifdef CONFIG_ZONE_DMA
324         /*
325          * The most common case is KMALLOC_NORMAL, so test for it
326          * with a single branch for both flags.
327          */
328         if (likely((flags & (__GFP_DMA | __GFP_RECLAIMABLE)) == 0))
329                 return KMALLOC_NORMAL;
330 
331         /*
332          * At least one of the flags has to be set. If both are, __GFP_DMA
333          * is more important.
334          */
335         return flags & __GFP_DMA ? KMALLOC_DMA : KMALLOC_RECLAIM;
336 #else
337         return flags & __GFP_RECLAIMABLE ? KMALLOC_RECLAIM : KMALLOC_NORMAL;
338 #endif
339 }
340 
341 /*
342  * Figure out which kmalloc slab an allocation of a certain size
343  * belongs to.
344  * 0 = zero alloc
345  * 1 =  65 .. 96 bytes
346  * 2 = 129 .. 192 bytes
347  * n = 2^(n-1)+1 .. 2^n
348  */
349 static __always_inline unsigned int kmalloc_index(size_t size)
350 {
351         if (!size)
352                 return 0;
353 
354         if (size <= KMALLOC_MIN_SIZE)
355                 return KMALLOC_SHIFT_LOW;
356 
357         if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
358                 return 1;
359         if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
360                 return 2;
361         if (size <=          8) return 3;
362         if (size <=         16) return 4;
363         if (size <=         32) return 5;
364         if (size <=         64) return 6;
365         if (size <=        128) return 7;
366         if (size <=        256) return 8;
367         if (size <=        512) return 9;
368         if (size <=       1024) return 10;
369         if (size <=   2 * 1024) return 11;
370         if (size <=   4 * 1024) return 12;
371         if (size <=   8 * 1024) return 13;
372         if (size <=  16 * 1024) return 14;
373         if (size <=  32 * 1024) return 15;
374         if (size <=  64 * 1024) return 16;
375         if (size <= 128 * 1024) return 17;
376         if (size <= 256 * 1024) return 18;
377         if (size <= 512 * 1024) return 19;
378         if (size <= 1024 * 1024) return 20;
379         if (size <=  2 * 1024 * 1024) return 21;
380         if (size <=  4 * 1024 * 1024) return 22;
381         if (size <=  8 * 1024 * 1024) return 23;
382         if (size <=  16 * 1024 * 1024) return 24;
383         if (size <=  32 * 1024 * 1024) return 25;
384         if (size <=  64 * 1024 * 1024) return 26;
385         BUG();
386 
387         /* Will never be reached. Needed because the compiler may complain */
388         return -1;
389 }
390 #endif /* !CONFIG_SLOB */
391 
392 void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc;
393 void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags) __assume_slab_alignment __malloc;
394 void kmem_cache_free(struct kmem_cache *, void *);
395 
396 /*
397  * Bulk allocation and freeing operations. These are accelerated in an
398  * allocator specific way to avoid taking locks repeatedly or building
399  * metadata structures unnecessarily.
400  *
401  * Note that interrupts must be enabled when calling these functions.
402  */
403 void kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
404 int kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
405 
406 /*
407  * Caller must not use kfree_bulk() on memory not originally allocated
408  * by kmalloc(), because the SLOB allocator cannot handle this.
409  */
410 static __always_inline void kfree_bulk(size_t size, void **p)
411 {
412         kmem_cache_free_bulk(NULL, size, p);
413 }
414 
415 #ifdef CONFIG_NUMA
416 void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment __malloc;
417 void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node) __assume_slab_alignment __malloc;
418 #else
419 static __always_inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
420 {
421         return __kmalloc(size, flags);
422 }
423 
424 static __always_inline void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node)
425 {
426         return kmem_cache_alloc(s, flags);
427 }
428 #endif
429 
430 #ifdef CONFIG_TRACING
431 extern void *kmem_cache_alloc_trace(struct kmem_cache *, gfp_t, size_t) __assume_slab_alignment __malloc;
432 
433 #ifdef CONFIG_NUMA
434 extern void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
435                                            gfp_t gfpflags,
436                                            int node, size_t size) __assume_slab_alignment __malloc;
437 #else
438 static __always_inline void *
439 kmem_cache_alloc_node_trace(struct kmem_cache *s,
440                               gfp_t gfpflags,
441                               int node, size_t size)
442 {
443         return kmem_cache_alloc_trace(s, gfpflags, size);
444 }
445 #endif /* CONFIG_NUMA */
446 
447 #else /* CONFIG_TRACING */
448 static __always_inline void *kmem_cache_alloc_trace(struct kmem_cache *s,
449                 gfp_t flags, size_t size)
450 {
451         void *ret = kmem_cache_alloc(s, flags);
452 
453         ret = kasan_kmalloc(s, ret, size, flags);
454         return ret;
455 }
456 
457 static __always_inline void *
458 kmem_cache_alloc_node_trace(struct kmem_cache *s,
459                               gfp_t gfpflags,
460                               int node, size_t size)
461 {
462         void *ret = kmem_cache_alloc_node(s, gfpflags, node);
463 
464         ret = kasan_kmalloc(s, ret, size, gfpflags);
465         return ret;
466 }
467 #endif /* CONFIG_TRACING */
468 
469 extern void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) __assume_page_alignment __malloc;
470 
471 #ifdef CONFIG_TRACING
472 extern void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) __assume_page_alignment __malloc;
473 #else
474 static __always_inline void *
475 kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
476 {
477         return kmalloc_order(size, flags, order);
478 }
479 #endif
480 
481 static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
482 {
483         unsigned int order = get_order(size);
484         return kmalloc_order_trace(size, flags, order);
485 }
486 
487 /**
488  * kmalloc - allocate memory
489  * @size: how many bytes of memory are required.
490  * @flags: the type of memory to allocate.
491  *
492  * kmalloc is the normal method of allocating memory
493  * for objects smaller than page size in the kernel.
494  *
495  * The allocated object address is aligned to at least ARCH_KMALLOC_MINALIGN
496  * bytes. For @size of power of two bytes, the alignment is also guaranteed
497  * to be at least to the size.
498  *
499  * The @flags argument may be one of the GFP flags defined at
500  * include/linux/gfp.h and described at
501  * :ref:`Documentation/core-api/mm-api.rst <mm-api-gfp-flags>`
502  *
503  * The recommended usage of the @flags is described at
504  * :ref:`Documentation/core-api/memory-allocation.rst <memory-allocation>`
505  *
506  * Below is a brief outline of the most useful GFP flags
507  *
508  * %GFP_KERNEL
509  *      Allocate normal kernel ram. May sleep.
510  *
511  * %GFP_NOWAIT
512  *      Allocation will not sleep.
513  *
514  * %GFP_ATOMIC
515  *      Allocation will not sleep.  May use emergency pools.
516  *
517  * %GFP_HIGHUSER
518  *      Allocate memory from high memory on behalf of user.
519  *
520  * Also it is possible to set different flags by OR'ing
521  * in one or more of the following additional @flags:
522  *
523  * %__GFP_HIGH
524  *      This allocation has high priority and may use emergency pools.
525  *
526  * %__GFP_NOFAIL
527  *      Indicate that this allocation is in no way allowed to fail
528  *      (think twice before using).
529  *
530  * %__GFP_NORETRY
531  *      If memory is not immediately available,
532  *      then give up at once.
533  *
534  * %__GFP_NOWARN
535  *      If allocation fails, don't issue any warnings.
536  *
537  * %__GFP_RETRY_MAYFAIL
538  *      Try really hard to succeed the allocation but fail
539  *      eventually.
540  */
541 static __always_inline void *kmalloc(size_t size, gfp_t flags)
542 {
543         if (__builtin_constant_p(size)) {
544 #ifndef CONFIG_SLOB
545                 unsigned int index;
546 #endif
547                 if (size > KMALLOC_MAX_CACHE_SIZE)
548                         return kmalloc_large(size, flags);
549 #ifndef CONFIG_SLOB
550                 index = kmalloc_index(size);
551 
552                 if (!index)
553                         return ZERO_SIZE_PTR;
554 
555                 return kmem_cache_alloc_trace(
556                                 kmalloc_caches[kmalloc_type(flags)][index],
557                                 flags, size);
558 #endif
559         }
560         return __kmalloc(size, flags);
561 }
562 
563 static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
564 {
565 #ifndef CONFIG_SLOB
566         if (__builtin_constant_p(size) &&
567                 size <= KMALLOC_MAX_CACHE_SIZE) {
568                 unsigned int i = kmalloc_index(size);
569 
570                 if (!i)
571                         return ZERO_SIZE_PTR;
572 
573                 return kmem_cache_alloc_node_trace(
574                                 kmalloc_caches[kmalloc_type(flags)][i],
575                                                 flags, node, size);
576         }
577 #endif
578         return __kmalloc_node(size, flags, node);
579 }
580 
581 int memcg_update_all_caches(int num_memcgs);
582 
583 /**
584  * kmalloc_array - allocate memory for an array.
585  * @n: number of elements.
586  * @size: element size.
587  * @flags: the type of memory to allocate (see kmalloc).
588  */
589 static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
590 {
591         size_t bytes;
592 
593         if (unlikely(check_mul_overflow(n, size, &bytes)))
594                 return NULL;
595         if (__builtin_constant_p(n) && __builtin_constant_p(size))
596                 return kmalloc(bytes, flags);
597         return __kmalloc(bytes, flags);
598 }
599 
600 /**
601  * kcalloc - allocate memory for an array. The memory is set to zero.
602  * @n: number of elements.
603  * @size: element size.
604  * @flags: the type of memory to allocate (see kmalloc).
605  */
606 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
607 {
608         return kmalloc_array(n, size, flags | __GFP_ZERO);
609 }
610 
611 /*
612  * kmalloc_track_caller is a special version of kmalloc that records the
613  * calling function of the routine calling it for slab leak tracking instead
614  * of just the calling function (confusing, eh?).
615  * It's useful when the call to kmalloc comes from a widely-used standard
616  * allocator where we care about the real place the memory allocation
617  * request comes from.
618  */
619 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
620 #define kmalloc_track_caller(size, flags) \
621         __kmalloc_track_caller(size, flags, _RET_IP_)
622 
623 static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
624                                        int node)
625 {
626         size_t bytes;
627 
628         if (unlikely(check_mul_overflow(n, size, &bytes)))
629                 return NULL;
630         if (__builtin_constant_p(n) && __builtin_constant_p(size))
631                 return kmalloc_node(bytes, flags, node);
632         return __kmalloc_node(bytes, flags, node);
633 }
634 
635 static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
636 {
637         return kmalloc_array_node(n, size, flags | __GFP_ZERO, node);
638 }
639 
640 
641 #ifdef CONFIG_NUMA
642 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
643 #define kmalloc_node_track_caller(size, flags, node) \
644         __kmalloc_node_track_caller(size, flags, node, \
645                         _RET_IP_)
646 
647 #else /* CONFIG_NUMA */
648 
649 #define kmalloc_node_track_caller(size, flags, node) \
650         kmalloc_track_caller(size, flags)
651 
652 #endif /* CONFIG_NUMA */
653 
654 /*
655  * Shortcuts
656  */
657 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
658 {
659         return kmem_cache_alloc(k, flags | __GFP_ZERO);
660 }
661 
662 /**
663  * kzalloc - allocate memory. The memory is set to zero.
664  * @size: how many bytes of memory are required.
665  * @flags: the type of memory to allocate (see kmalloc).
666  */
667 static inline void *kzalloc(size_t size, gfp_t flags)
668 {
669         return kmalloc(size, flags | __GFP_ZERO);
670 }
671 
672 /**
673  * kzalloc_node - allocate zeroed memory from a particular memory node.
674  * @size: how many bytes of memory are required.
675  * @flags: the type of memory to allocate (see kmalloc).
676  * @node: memory node from which to allocate
677  */
678 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
679 {
680         return kmalloc_node(size, flags | __GFP_ZERO, node);
681 }
682 
683 unsigned int kmem_cache_size(struct kmem_cache *s);
684 void __init kmem_cache_init_late(void);
685 
686 #if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
687 int slab_prepare_cpu(unsigned int cpu);
688 int slab_dead_cpu(unsigned int cpu);
689 #else
690 #define slab_prepare_cpu        NULL
691 #define slab_dead_cpu           NULL
692 #endif
693 
694 #endif  /* _LINUX_SLAB_H */
695 

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