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/cache.h>
16#include <linux/gfp.h>
17#include <linux/overflow.h>
18#include <linux/types.h>
19#include <linux/workqueue.h>
20#include <linux/percpu-refcount.h>
21#include <linux/cleanup.h>
22#include <linux/hash.h>
23
24
25/*
26 * Flags to pass to kmem_cache_create().
27 * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
28 */
29/* DEBUG: Perform (expensive) checks on alloc/free */
30#define SLAB_CONSISTENCY_CHECKS ((slab_flags_t __force)0x00000100U)
31/* DEBUG: Red zone objs in a cache */
32#define SLAB_RED_ZONE ((slab_flags_t __force)0x00000400U)
33/* DEBUG: Poison objects */
34#define SLAB_POISON ((slab_flags_t __force)0x00000800U)
35/* Indicate a kmalloc slab */
36#define SLAB_KMALLOC ((slab_flags_t __force)0x00001000U)
37/* Align objs on cache lines */
38#define SLAB_HWCACHE_ALIGN ((slab_flags_t __force)0x00002000U)
39/* Use GFP_DMA memory */
40#define SLAB_CACHE_DMA ((slab_flags_t __force)0x00004000U)
41/* Use GFP_DMA32 memory */
42#define SLAB_CACHE_DMA32 ((slab_flags_t __force)0x00008000U)
43/* DEBUG: Store the last owner for bug hunting */
44#define SLAB_STORE_USER ((slab_flags_t __force)0x00010000U)
45/* Panic if kmem_cache_create() fails */
46#define SLAB_PANIC ((slab_flags_t __force)0x00040000U)
47/*
48 * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
49 *
50 * This delays freeing the SLAB page by a grace period, it does _NOT_
51 * delay object freeing. This means that if you do kmem_cache_free()
52 * that memory location is free to be reused at any time. Thus it may
53 * be possible to see another object there in the same RCU grace period.
54 *
55 * This feature only ensures the memory location backing the object
56 * stays valid, the trick to using this is relying on an independent
57 * object validation pass. Something like:
58 *
59 * begin:
60 * rcu_read_lock();
61 * obj = lockless_lookup(key);
62 * if (obj) {
63 * if (!try_get_ref(obj)) // might fail for free objects
64 * rcu_read_unlock();
65 * goto begin;
66 *
67 * if (obj->key != key) { // not the object we expected
68 * put_ref(obj);
69 * rcu_read_unlock();
70 * goto begin;
71 * }
72 * }
73 * rcu_read_unlock();
74 *
75 * This is useful if we need to approach a kernel structure obliquely,
76 * from its address obtained without the usual locking. We can lock
77 * the structure to stabilize it and check it's still at the given address,
78 * only if we can be sure that the memory has not been meanwhile reused
79 * for some other kind of object (which our subsystem's lock might corrupt).
80 *
81 * rcu_read_lock before reading the address, then rcu_read_unlock after
82 * taking the spinlock within the structure expected at that address.
83 *
84 * Note that it is not possible to acquire a lock within a structure
85 * allocated with SLAB_TYPESAFE_BY_RCU without first acquiring a reference
86 * as described above. The reason is that SLAB_TYPESAFE_BY_RCU pages
87 * are not zeroed before being given to the slab, which means that any
88 * locks must be initialized after each and every kmem_struct_alloc().
89 * Alternatively, make the ctor passed to kmem_cache_create() initialize
90 * the locks at page-allocation time, as is done in __i915_request_ctor(),
91 * sighand_ctor(), and anon_vma_ctor(). Such a ctor permits readers
92 * to safely acquire those ctor-initialized locks under rcu_read_lock()
93 * protection.
94 *
95 * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
96 */
97/* Defer freeing slabs to RCU */
98#define SLAB_TYPESAFE_BY_RCU ((slab_flags_t __force)0x00080000U)
99/* Spread some memory over cpuset */
100#define SLAB_MEM_SPREAD ((slab_flags_t __force)0x00100000U)
101/* Trace allocations and frees */
102#define SLAB_TRACE ((slab_flags_t __force)0x00200000U)
103
104/* Flag to prevent checks on free */
105#ifdef CONFIG_DEBUG_OBJECTS
106# define SLAB_DEBUG_OBJECTS ((slab_flags_t __force)0x00400000U)
107#else
108# define SLAB_DEBUG_OBJECTS 0
109#endif
110
111/* Avoid kmemleak tracing */
112#define SLAB_NOLEAKTRACE ((slab_flags_t __force)0x00800000U)
113
114/*
115 * Prevent merging with compatible kmem caches. This flag should be used
116 * cautiously. Valid use cases:
117 *
118 * - caches created for self-tests (e.g. kunit)
119 * - general caches created and used by a subsystem, only when a
120 * (subsystem-specific) debug option is enabled
121 * - performance critical caches, should be very rare and consulted with slab
122 * maintainers, and not used together with CONFIG_SLUB_TINY
123 */
124#define SLAB_NO_MERGE ((slab_flags_t __force)0x01000000U)
125
126/* Fault injection mark */
127#ifdef CONFIG_FAILSLAB
128# define SLAB_FAILSLAB ((slab_flags_t __force)0x02000000U)
129#else
130# define SLAB_FAILSLAB 0
131#endif
132/* Account to memcg */
133#ifdef CONFIG_MEMCG_KMEM
134# define SLAB_ACCOUNT ((slab_flags_t __force)0x04000000U)
135#else
136# define SLAB_ACCOUNT 0
137#endif
138
139#ifdef CONFIG_KASAN_GENERIC
140#define SLAB_KASAN ((slab_flags_t __force)0x08000000U)
141#else
142#define SLAB_KASAN 0
143#endif
144
145/*
146 * Ignore user specified debugging flags.
147 * Intended for caches created for self-tests so they have only flags
148 * specified in the code and other flags are ignored.
149 */
150#define SLAB_NO_USER_FLAGS ((slab_flags_t __force)0x10000000U)
151
152#ifdef CONFIG_KFENCE
153#define SLAB_SKIP_KFENCE ((slab_flags_t __force)0x20000000U)
154#else
155#define SLAB_SKIP_KFENCE 0
156#endif
157
158/* The following flags affect the page allocator grouping pages by mobility */
159/* Objects are reclaimable */
160#ifndef CONFIG_SLUB_TINY
161#define SLAB_RECLAIM_ACCOUNT ((slab_flags_t __force)0x00020000U)
162#else
163#define SLAB_RECLAIM_ACCOUNT ((slab_flags_t __force)0)
164#endif
165#define SLAB_TEMPORARY SLAB_RECLAIM_ACCOUNT /* Objects are short-lived */
166
167/*
168 * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
169 *
170 * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
171 *
172 * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
173 * Both make kfree a no-op.
174 */
175#define ZERO_SIZE_PTR ((void *)16)
176
177#define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
178 (unsigned long)ZERO_SIZE_PTR)
179
180#include <linux/kasan.h>
181
182struct list_lru;
183struct mem_cgroup;
184/*
185 * struct kmem_cache related prototypes
186 */
187bool slab_is_available(void);
188
189struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
190 unsigned int align, slab_flags_t flags,
191 void (*ctor)(void *));
192struct kmem_cache *kmem_cache_create_usercopy(const char *name,
193 unsigned int size, unsigned int align,
194 slab_flags_t flags,
195 unsigned int useroffset, unsigned int usersize,
196 void (*ctor)(void *));
197void kmem_cache_destroy(struct kmem_cache *s);
198int kmem_cache_shrink(struct kmem_cache *s);
199
200/*
201 * Please use this macro to create slab caches. Simply specify the
202 * name of the structure and maybe some flags that are listed above.
203 *
204 * The alignment of the struct determines object alignment. If you
205 * f.e. add ____cacheline_aligned_in_smp to the struct declaration
206 * then the objects will be properly aligned in SMP configurations.
207 */
208#define KMEM_CACHE(__struct, __flags) \
209 kmem_cache_create(#__struct, sizeof(struct __struct), \
210 __alignof__(struct __struct), (__flags), NULL)
211
212/*
213 * To whitelist a single field for copying to/from usercopy, use this
214 * macro instead for KMEM_CACHE() above.
215 */
216#define KMEM_CACHE_USERCOPY(__struct, __flags, __field) \
217 kmem_cache_create_usercopy(#__struct, \
218 sizeof(struct __struct), \
219 __alignof__(struct __struct), (__flags), \
220 offsetof(struct __struct, __field), \
221 sizeof_field(struct __struct, __field), NULL)
222
223/*
224 * Common kmalloc functions provided by all allocators
225 */
226void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
227void kfree(const void *objp);
228void kfree_sensitive(const void *objp);
229size_t __ksize(const void *objp);
230
231DEFINE_FREE(kfree, void *, if (_T) kfree(_T))
232
233/**
234 * ksize - Report actual allocation size of associated object
235 *
236 * @objp: Pointer returned from a prior kmalloc()-family allocation.
237 *
238 * This should not be used for writing beyond the originally requested
239 * allocation size. Either use krealloc() or round up the allocation size
240 * with kmalloc_size_roundup() prior to allocation. If this is used to
241 * access beyond the originally requested allocation size, UBSAN_BOUNDS
242 * and/or FORTIFY_SOURCE may trip, since they only know about the
243 * originally allocated size via the __alloc_size attribute.
244 */
245size_t ksize(const void *objp);
246
247#ifdef CONFIG_PRINTK
248bool kmem_dump_obj(void *object);
249#else
250static inline bool kmem_dump_obj(void *object) { return false; }
251#endif
252
253/*
254 * Some archs want to perform DMA into kmalloc caches and need a guaranteed
255 * alignment larger than the alignment of a 64-bit integer.
256 * Setting ARCH_DMA_MINALIGN in arch headers allows that.
257 */
258#ifdef ARCH_HAS_DMA_MINALIGN
259#if ARCH_DMA_MINALIGN > 8 && !defined(ARCH_KMALLOC_MINALIGN)
260#define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
261#endif
262#endif
263
264#ifndef ARCH_KMALLOC_MINALIGN
265#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
266#elif ARCH_KMALLOC_MINALIGN > 8
267#define KMALLOC_MIN_SIZE ARCH_KMALLOC_MINALIGN
268#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
269#endif
270
271/*
272 * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
273 * Intended for arches that get misalignment faults even for 64 bit integer
274 * aligned buffers.
275 */
276#ifndef ARCH_SLAB_MINALIGN
277#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
278#endif
279
280/*
281 * Arches can define this function if they want to decide the minimum slab
282 * alignment at runtime. The value returned by the function must be a power
283 * of two and >= ARCH_SLAB_MINALIGN.
284 */
285#ifndef arch_slab_minalign
286static inline unsigned int arch_slab_minalign(void)
287{
288 return ARCH_SLAB_MINALIGN;
289}
290#endif
291
292/*
293 * kmem_cache_alloc and friends return pointers aligned to ARCH_SLAB_MINALIGN.
294 * kmalloc and friends return pointers aligned to both ARCH_KMALLOC_MINALIGN
295 * and ARCH_SLAB_MINALIGN, but here we only assume the former alignment.
296 */
297#define __assume_kmalloc_alignment __assume_aligned(ARCH_KMALLOC_MINALIGN)
298#define __assume_slab_alignment __assume_aligned(ARCH_SLAB_MINALIGN)
299#define __assume_page_alignment __assume_aligned(PAGE_SIZE)
300
301/*
302 * Kmalloc array related definitions
303 */
304
305#ifdef CONFIG_SLAB
306/*
307 * SLAB and SLUB directly allocates requests fitting in to an order-1 page
308 * (PAGE_SIZE*2). Larger requests are passed to the page allocator.
309 */
310#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
311#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
312#ifndef KMALLOC_SHIFT_LOW
313#define KMALLOC_SHIFT_LOW 5
314#endif
315#endif
316
317#ifdef CONFIG_SLUB
318#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
319#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
320#ifndef KMALLOC_SHIFT_LOW
321#define KMALLOC_SHIFT_LOW 3
322#endif
323#endif
324
325/* Maximum allocatable size */
326#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_MAX)
327/* Maximum size for which we actually use a slab cache */
328#define KMALLOC_MAX_CACHE_SIZE (1UL << KMALLOC_SHIFT_HIGH)
329/* Maximum order allocatable via the slab allocator */
330#define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
331
332/*
333 * Kmalloc subsystem.
334 */
335#ifndef KMALLOC_MIN_SIZE
336#define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
337#endif
338
339/*
340 * This restriction comes from byte sized index implementation.
341 * Page size is normally 2^12 bytes and, in this case, if we want to use
342 * byte sized index which can represent 2^8 entries, the size of the object
343 * should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
344 * If minimum size of kmalloc is less than 16, we use it as minimum object
345 * size and give up to use byte sized index.
346 */
347#define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \
348 (KMALLOC_MIN_SIZE) : 16)
349
350#ifdef CONFIG_RANDOM_KMALLOC_CACHES
351#define RANDOM_KMALLOC_CACHES_NR 15 // # of cache copies
352#else
353#define RANDOM_KMALLOC_CACHES_NR 0
354#endif
355
356/*
357 * Whenever changing this, take care of that kmalloc_type() and
358 * create_kmalloc_caches() still work as intended.
359 *
360 * KMALLOC_NORMAL can contain only unaccounted objects whereas KMALLOC_CGROUP
361 * is for accounted but unreclaimable and non-dma objects. All the other
362 * kmem caches can have both accounted and unaccounted objects.
363 */
364enum kmalloc_cache_type {
365 KMALLOC_NORMAL = 0,
366#ifndef CONFIG_ZONE_DMA
367 KMALLOC_DMA = KMALLOC_NORMAL,
368#endif
369#ifndef CONFIG_MEMCG_KMEM
370 KMALLOC_CGROUP = KMALLOC_NORMAL,
371#endif
372 KMALLOC_RANDOM_START = KMALLOC_NORMAL,
373 KMALLOC_RANDOM_END = KMALLOC_RANDOM_START + RANDOM_KMALLOC_CACHES_NR,
374#ifdef CONFIG_SLUB_TINY
375 KMALLOC_RECLAIM = KMALLOC_NORMAL,
376#else
377 KMALLOC_RECLAIM,
378#endif
379#ifdef CONFIG_ZONE_DMA
380 KMALLOC_DMA,
381#endif
382#ifdef CONFIG_MEMCG_KMEM
383 KMALLOC_CGROUP,
384#endif
385 NR_KMALLOC_TYPES
386};
387
388extern struct kmem_cache *
389kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
390
391/*
392 * Define gfp bits that should not be set for KMALLOC_NORMAL.
393 */
394#define KMALLOC_NOT_NORMAL_BITS \
395 (__GFP_RECLAIMABLE | \
396 (IS_ENABLED(CONFIG_ZONE_DMA) ? __GFP_DMA : 0) | \
397 (IS_ENABLED(CONFIG_MEMCG_KMEM) ? __GFP_ACCOUNT : 0))
398
399extern unsigned long random_kmalloc_seed;
400
401static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags, unsigned long caller)
402{
403 /*
404 * The most common case is KMALLOC_NORMAL, so test for it
405 * with a single branch for all the relevant flags.
406 */
407 if (likely((flags & KMALLOC_NOT_NORMAL_BITS) == 0))
408#ifdef CONFIG_RANDOM_KMALLOC_CACHES
409 /* RANDOM_KMALLOC_CACHES_NR (=15) copies + the KMALLOC_NORMAL */
410 return KMALLOC_RANDOM_START + hash_64(caller ^ random_kmalloc_seed,
411 ilog2(RANDOM_KMALLOC_CACHES_NR + 1));
412#else
413 return KMALLOC_NORMAL;
414#endif
415
416 /*
417 * At least one of the flags has to be set. Their priorities in
418 * decreasing order are:
419 * 1) __GFP_DMA
420 * 2) __GFP_RECLAIMABLE
421 * 3) __GFP_ACCOUNT
422 */
423 if (IS_ENABLED(CONFIG_ZONE_DMA) && (flags & __GFP_DMA))
424 return KMALLOC_DMA;
425 if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || (flags & __GFP_RECLAIMABLE))
426 return KMALLOC_RECLAIM;
427 else
428 return KMALLOC_CGROUP;
429}
430
431/*
432 * Figure out which kmalloc slab an allocation of a certain size
433 * belongs to.
434 * 0 = zero alloc
435 * 1 = 65 .. 96 bytes
436 * 2 = 129 .. 192 bytes
437 * n = 2^(n-1)+1 .. 2^n
438 *
439 * Note: __kmalloc_index() is compile-time optimized, and not runtime optimized;
440 * typical usage is via kmalloc_index() and therefore evaluated at compile-time.
441 * Callers where !size_is_constant should only be test modules, where runtime
442 * overheads of __kmalloc_index() can be tolerated. Also see kmalloc_slab().
443 */
444static __always_inline unsigned int __kmalloc_index(size_t size,
445 bool size_is_constant)
446{
447 if (!size)
448 return 0;
449
450 if (size <= KMALLOC_MIN_SIZE)
451 return KMALLOC_SHIFT_LOW;
452
453 if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
454 return 1;
455 if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
456 return 2;
457 if (size <= 8) return 3;
458 if (size <= 16) return 4;
459 if (size <= 32) return 5;
460 if (size <= 64) return 6;
461 if (size <= 128) return 7;
462 if (size <= 256) return 8;
463 if (size <= 512) return 9;
464 if (size <= 1024) return 10;
465 if (size <= 2 * 1024) return 11;
466 if (size <= 4 * 1024) return 12;
467 if (size <= 8 * 1024) return 13;
468 if (size <= 16 * 1024) return 14;
469 if (size <= 32 * 1024) return 15;
470 if (size <= 64 * 1024) return 16;
471 if (size <= 128 * 1024) return 17;
472 if (size <= 256 * 1024) return 18;
473 if (size <= 512 * 1024) return 19;
474 if (size <= 1024 * 1024) return 20;
475 if (size <= 2 * 1024 * 1024) return 21;
476
477 if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES) && size_is_constant)
478 BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
479 else
480 BUG();
481
482 /* Will never be reached. Needed because the compiler may complain */
483 return -1;
484}
485static_assert(PAGE_SHIFT <= 20);
486#define kmalloc_index(s) __kmalloc_index(s, true)
487
488void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
489
490/**
491 * kmem_cache_alloc - Allocate an object
492 * @cachep: The cache to allocate from.
493 * @flags: See kmalloc().
494 *
495 * Allocate an object from this cache.
496 * See kmem_cache_zalloc() for a shortcut of adding __GFP_ZERO to flags.
497 *
498 * Return: pointer to the new object or %NULL in case of error
499 */
500void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) __assume_slab_alignment __malloc;
501void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
502 gfp_t gfpflags) __assume_slab_alignment __malloc;
503void kmem_cache_free(struct kmem_cache *s, void *objp);
504
505/*
506 * Bulk allocation and freeing operations. These are accelerated in an
507 * allocator specific way to avoid taking locks repeatedly or building
508 * metadata structures unnecessarily.
509 *
510 * Note that interrupts must be enabled when calling these functions.
511 */
512void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p);
513int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p);
514
515static __always_inline void kfree_bulk(size_t size, void **p)
516{
517 kmem_cache_free_bulk(NULL, size, p);
518}
519
520void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment
521 __alloc_size(1);
522void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node) __assume_slab_alignment
523 __malloc;
524
525void *kmalloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
526 __assume_kmalloc_alignment __alloc_size(3);
527
528void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
529 int node, size_t size) __assume_kmalloc_alignment
530 __alloc_size(4);
531void *kmalloc_large(size_t size, gfp_t flags) __assume_page_alignment
532 __alloc_size(1);
533
534void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_alignment
535 __alloc_size(1);
536
537/**
538 * kmalloc - allocate kernel memory
539 * @size: how many bytes of memory are required.
540 * @flags: describe the allocation context
541 *
542 * kmalloc is the normal method of allocating memory
543 * for objects smaller than page size in the kernel.
544 *
545 * The allocated object address is aligned to at least ARCH_KMALLOC_MINALIGN
546 * bytes. For @size of power of two bytes, the alignment is also guaranteed
547 * to be at least to the size.
548 *
549 * The @flags argument may be one of the GFP flags defined at
550 * include/linux/gfp_types.h and described at
551 * :ref:`Documentation/core-api/mm-api.rst <mm-api-gfp-flags>`
552 *
553 * The recommended usage of the @flags is described at
554 * :ref:`Documentation/core-api/memory-allocation.rst <memory_allocation>`
555 *
556 * Below is a brief outline of the most useful GFP flags
557 *
558 * %GFP_KERNEL
559 * Allocate normal kernel ram. May sleep.
560 *
561 * %GFP_NOWAIT
562 * Allocation will not sleep.
563 *
564 * %GFP_ATOMIC
565 * Allocation will not sleep. May use emergency pools.
566 *
567 * Also it is possible to set different flags by OR'ing
568 * in one or more of the following additional @flags:
569 *
570 * %__GFP_ZERO
571 * Zero the allocated memory before returning. Also see kzalloc().
572 *
573 * %__GFP_HIGH
574 * This allocation has high priority and may use emergency pools.
575 *
576 * %__GFP_NOFAIL
577 * Indicate that this allocation is in no way allowed to fail
578 * (think twice before using).
579 *
580 * %__GFP_NORETRY
581 * If memory is not immediately available,
582 * then give up at once.
583 *
584 * %__GFP_NOWARN
585 * If allocation fails, don't issue any warnings.
586 *
587 * %__GFP_RETRY_MAYFAIL
588 * Try really hard to succeed the allocation but fail
589 * eventually.
590 */
591static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
592{
593 if (__builtin_constant_p(size) && size) {
594 unsigned int index;
595
596 if (size > KMALLOC_MAX_CACHE_SIZE)
597 return kmalloc_large(size, flags);
598
599 index = kmalloc_index(size);
600 return kmalloc_trace(
601 s: kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
602 flags, size);
603 }
604 return __kmalloc(size, flags);
605}
606
607static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
608{
609 if (__builtin_constant_p(size) && size) {
610 unsigned int index;
611
612 if (size > KMALLOC_MAX_CACHE_SIZE)
613 return kmalloc_large_node(size, flags, node);
614
615 index = kmalloc_index(size);
616 return kmalloc_node_trace(
617 s: kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
618 gfpflags: flags, node, size);
619 }
620 return __kmalloc_node(size, flags, node);
621}
622
623/**
624 * kmalloc_array - allocate memory for an array.
625 * @n: number of elements.
626 * @size: element size.
627 * @flags: the type of memory to allocate (see kmalloc).
628 */
629static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_t flags)
630{
631 size_t bytes;
632
633 if (unlikely(check_mul_overflow(n, size, &bytes)))
634 return NULL;
635 if (__builtin_constant_p(n) && __builtin_constant_p(size))
636 return kmalloc(size: bytes, flags);
637 return __kmalloc(size: bytes, flags);
638}
639
640/**
641 * krealloc_array - reallocate memory for an array.
642 * @p: pointer to the memory chunk to reallocate
643 * @new_n: new number of elements to alloc
644 * @new_size: new size of a single member of the array
645 * @flags: the type of memory to allocate (see kmalloc)
646 */
647static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
648 size_t new_n,
649 size_t new_size,
650 gfp_t flags)
651{
652 size_t bytes;
653
654 if (unlikely(check_mul_overflow(new_n, new_size, &bytes)))
655 return NULL;
656
657 return krealloc(objp: p, new_size: bytes, flags);
658}
659
660/**
661 * kcalloc - allocate memory for an array. The memory is set to zero.
662 * @n: number of elements.
663 * @size: element size.
664 * @flags: the type of memory to allocate (see kmalloc).
665 */
666static inline __alloc_size(1, 2) void *kcalloc(size_t n, size_t size, gfp_t flags)
667{
668 return kmalloc_array(n, size, flags: flags | __GFP_ZERO);
669}
670
671void *__kmalloc_node_track_caller(size_t size, gfp_t flags, int node,
672 unsigned long caller) __alloc_size(1);
673#define kmalloc_node_track_caller(size, flags, node) \
674 __kmalloc_node_track_caller(size, flags, node, \
675 _RET_IP_)
676
677/*
678 * kmalloc_track_caller is a special version of kmalloc that records the
679 * calling function of the routine calling it for slab leak tracking instead
680 * of just the calling function (confusing, eh?).
681 * It's useful when the call to kmalloc comes from a widely-used standard
682 * allocator where we care about the real place the memory allocation
683 * request comes from.
684 */
685#define kmalloc_track_caller(size, flags) \
686 __kmalloc_node_track_caller(size, flags, \
687 NUMA_NO_NODE, _RET_IP_)
688
689static inline __alloc_size(1, 2) void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
690 int node)
691{
692 size_t bytes;
693
694 if (unlikely(check_mul_overflow(n, size, &bytes)))
695 return NULL;
696 if (__builtin_constant_p(n) && __builtin_constant_p(size))
697 return kmalloc_node(size: bytes, flags, node);
698 return __kmalloc_node(size: bytes, flags, node);
699}
700
701static inline __alloc_size(1, 2) void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
702{
703 return kmalloc_array_node(n, size, flags: flags | __GFP_ZERO, node);
704}
705
706/*
707 * Shortcuts
708 */
709static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
710{
711 return kmem_cache_alloc(cachep: k, flags: flags | __GFP_ZERO);
712}
713
714/**
715 * kzalloc - allocate memory. The memory is set to zero.
716 * @size: how many bytes of memory are required.
717 * @flags: the type of memory to allocate (see kmalloc).
718 */
719static inline __alloc_size(1) void *kzalloc(size_t size, gfp_t flags)
720{
721 return kmalloc(size, flags: flags | __GFP_ZERO);
722}
723
724/**
725 * kzalloc_node - allocate zeroed memory from a particular memory node.
726 * @size: how many bytes of memory are required.
727 * @flags: the type of memory to allocate (see kmalloc).
728 * @node: memory node from which to allocate
729 */
730static inline __alloc_size(1) void *kzalloc_node(size_t size, gfp_t flags, int node)
731{
732 return kmalloc_node(size, flags: flags | __GFP_ZERO, node);
733}
734
735extern void *kvmalloc_node(size_t size, gfp_t flags, int node) __alloc_size(1);
736static inline __alloc_size(1) void *kvmalloc(size_t size, gfp_t flags)
737{
738 return kvmalloc_node(size, flags, NUMA_NO_NODE);
739}
740static inline __alloc_size(1) void *kvzalloc_node(size_t size, gfp_t flags, int node)
741{
742 return kvmalloc_node(size, flags: flags | __GFP_ZERO, node);
743}
744static inline __alloc_size(1) void *kvzalloc(size_t size, gfp_t flags)
745{
746 return kvmalloc(size, flags: flags | __GFP_ZERO);
747}
748
749static inline __alloc_size(1, 2) void *kvmalloc_array(size_t n, size_t size, gfp_t flags)
750{
751 size_t bytes;
752
753 if (unlikely(check_mul_overflow(n, size, &bytes)))
754 return NULL;
755
756 return kvmalloc(size: bytes, flags);
757}
758
759static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t flags)
760{
761 return kvmalloc_array(n, size, flags: flags | __GFP_ZERO);
762}
763
764extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
765 __realloc_size(3);
766extern void kvfree(const void *addr);
767DEFINE_FREE(kvfree, void *, if (_T) kvfree(_T))
768
769extern void kvfree_sensitive(const void *addr, size_t len);
770
771unsigned int kmem_cache_size(struct kmem_cache *s);
772
773/**
774 * kmalloc_size_roundup - Report allocation bucket size for the given size
775 *
776 * @size: Number of bytes to round up from.
777 *
778 * This returns the number of bytes that would be available in a kmalloc()
779 * allocation of @size bytes. For example, a 126 byte request would be
780 * rounded up to the next sized kmalloc bucket, 128 bytes. (This is strictly
781 * for the general-purpose kmalloc()-based allocations, and is not for the
782 * pre-sized kmem_cache_alloc()-based allocations.)
783 *
784 * Use this to kmalloc() the full bucket size ahead of time instead of using
785 * ksize() to query the size after an allocation.
786 */
787size_t kmalloc_size_roundup(size_t size);
788
789void __init kmem_cache_init_late(void);
790
791#if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
792int slab_prepare_cpu(unsigned int cpu);
793int slab_dead_cpu(unsigned int cpu);
794#else
795#define slab_prepare_cpu NULL
796#define slab_dead_cpu NULL
797#endif
798
799#endif /* _LINUX_SLAB_H */
800

source code of linux/include/linux/slab.h