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Linux/include/linux/slab.h

  1 /*
  2  * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
  3  *
  4  * (C) SGI 2006, Christoph Lameter
  5  *      Cleaned up and restructured to ease the addition of alternative
  6  *      implementations of SLAB allocators.
  7  * (C) Linux Foundation 2008-2013
  8  *      Unified interface for all slab allocators
  9  */
 10 
 11 #ifndef _LINUX_SLAB_H
 12 #define _LINUX_SLAB_H
 13 
 14 #include <linux/gfp.h>
 15 #include <linux/types.h>
 16 #include <linux/workqueue.h>
 17 
 18 
 19 /*
 20  * Flags to pass to kmem_cache_create().
 21  * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
 22  */
 23 #define SLAB_DEBUG_FREE         0x00000100UL    /* DEBUG: Perform (expensive) checks on free */
 24 #define SLAB_RED_ZONE           0x00000400UL    /* DEBUG: Red zone objs in a cache */
 25 #define SLAB_POISON             0x00000800UL    /* DEBUG: Poison objects */
 26 #define SLAB_HWCACHE_ALIGN      0x00002000UL    /* Align objs on cache lines */
 27 #define SLAB_CACHE_DMA          0x00004000UL    /* Use GFP_DMA memory */
 28 #define SLAB_STORE_USER         0x00010000UL    /* DEBUG: Store the last owner for bug hunting */
 29 #define SLAB_PANIC              0x00040000UL    /* Panic if kmem_cache_create() fails */
 30 /*
 31  * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
 32  *
 33  * This delays freeing the SLAB page by a grace period, it does _NOT_
 34  * delay object freeing. This means that if you do kmem_cache_free()
 35  * that memory location is free to be reused at any time. Thus it may
 36  * be possible to see another object there in the same RCU grace period.
 37  *
 38  * This feature only ensures the memory location backing the object
 39  * stays valid, the trick to using this is relying on an independent
 40  * object validation pass. Something like:
 41  *
 42  *  rcu_read_lock()
 43  * again:
 44  *  obj = lockless_lookup(key);
 45  *  if (obj) {
 46  *    if (!try_get_ref(obj)) // might fail for free objects
 47  *      goto again;
 48  *
 49  *    if (obj->key != key) { // not the object we expected
 50  *      put_ref(obj);
 51  *      goto again;
 52  *    }
 53  *  }
 54  *  rcu_read_unlock();
 55  *
 56  * This is useful if we need to approach a kernel structure obliquely,
 57  * from its address obtained without the usual locking. We can lock
 58  * the structure to stabilize it and check it's still at the given address,
 59  * only if we can be sure that the memory has not been meanwhile reused
 60  * for some other kind of object (which our subsystem's lock might corrupt).
 61  *
 62  * rcu_read_lock before reading the address, then rcu_read_unlock after
 63  * taking the spinlock within the structure expected at that address.
 64  */
 65 #define SLAB_DESTROY_BY_RCU     0x00080000UL    /* Defer freeing slabs to RCU */
 66 #define SLAB_MEM_SPREAD         0x00100000UL    /* Spread some memory over cpuset */
 67 #define SLAB_TRACE              0x00200000UL    /* Trace allocations and frees */
 68 
 69 /* Flag to prevent checks on free */
 70 #ifdef CONFIG_DEBUG_OBJECTS
 71 # define SLAB_DEBUG_OBJECTS     0x00400000UL
 72 #else
 73 # define SLAB_DEBUG_OBJECTS     0x00000000UL
 74 #endif
 75 
 76 #define SLAB_NOLEAKTRACE        0x00800000UL    /* Avoid kmemleak tracing */
 77 
 78 /* Don't track use of uninitialized memory */
 79 #ifdef CONFIG_KMEMCHECK
 80 # define SLAB_NOTRACK           0x01000000UL
 81 #else
 82 # define SLAB_NOTRACK           0x00000000UL
 83 #endif
 84 #ifdef CONFIG_FAILSLAB
 85 # define SLAB_FAILSLAB          0x02000000UL    /* Fault injection mark */
 86 #else
 87 # define SLAB_FAILSLAB          0x00000000UL
 88 #endif
 89 
 90 /* The following flags affect the page allocator grouping pages by mobility */
 91 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
 92 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
 93 /*
 94  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
 95  *
 96  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
 97  *
 98  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
 99  * Both make kfree a no-op.
100  */
101 #define ZERO_SIZE_PTR ((void *)16)
102 
103 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
104                                 (unsigned long)ZERO_SIZE_PTR)
105 
106 #include <linux/kmemleak.h>
107 #include <linux/kasan.h>
108 
109 struct mem_cgroup;
110 /*
111  * struct kmem_cache related prototypes
112  */
113 void __init kmem_cache_init(void);
114 int slab_is_available(void);
115 
116 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
117                         unsigned long,
118                         void (*)(void *));
119 void kmem_cache_destroy(struct kmem_cache *);
120 int kmem_cache_shrink(struct kmem_cache *);
121 
122 void memcg_create_kmem_cache(struct mem_cgroup *, struct kmem_cache *);
123 void memcg_deactivate_kmem_caches(struct mem_cgroup *);
124 void memcg_destroy_kmem_caches(struct mem_cgroup *);
125 
126 /*
127  * Please use this macro to create slab caches. Simply specify the
128  * name of the structure and maybe some flags that are listed above.
129  *
130  * The alignment of the struct determines object alignment. If you
131  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
132  * then the objects will be properly aligned in SMP configurations.
133  */
134 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
135                 sizeof(struct __struct), __alignof__(struct __struct),\
136                 (__flags), NULL)
137 
138 /*
139  * Common kmalloc functions provided by all allocators
140  */
141 void * __must_check __krealloc(const void *, size_t, gfp_t);
142 void * __must_check krealloc(const void *, size_t, gfp_t);
143 void kfree(const void *);
144 void kzfree(const void *);
145 size_t ksize(const void *);
146 
147 /*
148  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
149  * alignment larger than the alignment of a 64-bit integer.
150  * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
151  */
152 #if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
153 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
154 #define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
155 #define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
156 #else
157 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
158 #endif
159 
160 /*
161  * Kmalloc array related definitions
162  */
163 
164 #ifdef CONFIG_SLAB
165 /*
166  * The largest kmalloc size supported by the SLAB allocators is
167  * 32 megabyte (2^25) or the maximum allocatable page order if that is
168  * less than 32 MB.
169  *
170  * WARNING: Its not easy to increase this value since the allocators have
171  * to do various tricks to work around compiler limitations in order to
172  * ensure proper constant folding.
173  */
174 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
175                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
176 #define KMALLOC_SHIFT_MAX       KMALLOC_SHIFT_HIGH
177 #ifndef KMALLOC_SHIFT_LOW
178 #define KMALLOC_SHIFT_LOW       5
179 #endif
180 #endif
181 
182 #ifdef CONFIG_SLUB
183 /*
184  * SLUB directly allocates requests fitting in to an order-1 page
185  * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
186  */
187 #define KMALLOC_SHIFT_HIGH      (PAGE_SHIFT + 1)
188 #define KMALLOC_SHIFT_MAX       (MAX_ORDER + PAGE_SHIFT)
189 #ifndef KMALLOC_SHIFT_LOW
190 #define KMALLOC_SHIFT_LOW       3
191 #endif
192 #endif
193 
194 #ifdef CONFIG_SLOB
195 /*
196  * SLOB passes all requests larger than one page to the page allocator.
197  * No kmalloc array is necessary since objects of different sizes can
198  * be allocated from the same page.
199  */
200 #define KMALLOC_SHIFT_HIGH      PAGE_SHIFT
201 #define KMALLOC_SHIFT_MAX       30
202 #ifndef KMALLOC_SHIFT_LOW
203 #define KMALLOC_SHIFT_LOW       3
204 #endif
205 #endif
206 
207 /* Maximum allocatable size */
208 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_MAX)
209 /* Maximum size for which we actually use a slab cache */
210 #define KMALLOC_MAX_CACHE_SIZE  (1UL << KMALLOC_SHIFT_HIGH)
211 /* Maximum order allocatable via the slab allocagtor */
212 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
213 
214 /*
215  * Kmalloc subsystem.
216  */
217 #ifndef KMALLOC_MIN_SIZE
218 #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
219 #endif
220 
221 /*
222  * This restriction comes from byte sized index implementation.
223  * Page size is normally 2^12 bytes and, in this case, if we want to use
224  * byte sized index which can represent 2^8 entries, the size of the object
225  * should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
226  * If minimum size of kmalloc is less than 16, we use it as minimum object
227  * size and give up to use byte sized index.
228  */
229 #define SLAB_OBJ_MIN_SIZE      (KMALLOC_MIN_SIZE < 16 ? \
230                                (KMALLOC_MIN_SIZE) : 16)
231 
232 #ifndef CONFIG_SLOB
233 extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
234 #ifdef CONFIG_ZONE_DMA
235 extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
236 #endif
237 
238 /*
239  * Figure out which kmalloc slab an allocation of a certain size
240  * belongs to.
241  * 0 = zero alloc
242  * 1 =  65 .. 96 bytes
243  * 2 = 120 .. 192 bytes
244  * n = 2^(n-1) .. 2^n -1
245  */
246 static __always_inline int kmalloc_index(size_t size)
247 {
248         if (!size)
249                 return 0;
250 
251         if (size <= KMALLOC_MIN_SIZE)
252                 return KMALLOC_SHIFT_LOW;
253 
254         if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
255                 return 1;
256         if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
257                 return 2;
258         if (size <=          8) return 3;
259         if (size <=         16) return 4;
260         if (size <=         32) return 5;
261         if (size <=         64) return 6;
262         if (size <=        128) return 7;
263         if (size <=        256) return 8;
264         if (size <=        512) return 9;
265         if (size <=       1024) return 10;
266         if (size <=   2 * 1024) return 11;
267         if (size <=   4 * 1024) return 12;
268         if (size <=   8 * 1024) return 13;
269         if (size <=  16 * 1024) return 14;
270         if (size <=  32 * 1024) return 15;
271         if (size <=  64 * 1024) return 16;
272         if (size <= 128 * 1024) return 17;
273         if (size <= 256 * 1024) return 18;
274         if (size <= 512 * 1024) return 19;
275         if (size <= 1024 * 1024) return 20;
276         if (size <=  2 * 1024 * 1024) return 21;
277         if (size <=  4 * 1024 * 1024) return 22;
278         if (size <=  8 * 1024 * 1024) return 23;
279         if (size <=  16 * 1024 * 1024) return 24;
280         if (size <=  32 * 1024 * 1024) return 25;
281         if (size <=  64 * 1024 * 1024) return 26;
282         BUG();
283 
284         /* Will never be reached. Needed because the compiler may complain */
285         return -1;
286 }
287 #endif /* !CONFIG_SLOB */
288 
289 void *__kmalloc(size_t size, gfp_t flags);
290 void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags);
291 void kmem_cache_free(struct kmem_cache *, void *);
292 
293 #ifdef CONFIG_NUMA
294 void *__kmalloc_node(size_t size, gfp_t flags, int node);
295 void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
296 #else
297 static __always_inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
298 {
299         return __kmalloc(size, flags);
300 }
301 
302 static __always_inline void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node)
303 {
304         return kmem_cache_alloc(s, flags);
305 }
306 #endif
307 
308 #ifdef CONFIG_TRACING
309 extern void *kmem_cache_alloc_trace(struct kmem_cache *, gfp_t, size_t);
310 
311 #ifdef CONFIG_NUMA
312 extern void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
313                                            gfp_t gfpflags,
314                                            int node, size_t size);
315 #else
316 static __always_inline void *
317 kmem_cache_alloc_node_trace(struct kmem_cache *s,
318                               gfp_t gfpflags,
319                               int node, size_t size)
320 {
321         return kmem_cache_alloc_trace(s, gfpflags, size);
322 }
323 #endif /* CONFIG_NUMA */
324 
325 #else /* CONFIG_TRACING */
326 static __always_inline void *kmem_cache_alloc_trace(struct kmem_cache *s,
327                 gfp_t flags, size_t size)
328 {
329         void *ret = kmem_cache_alloc(s, flags);
330 
331         kasan_kmalloc(s, ret, size);
332         return ret;
333 }
334 
335 static __always_inline void *
336 kmem_cache_alloc_node_trace(struct kmem_cache *s,
337                               gfp_t gfpflags,
338                               int node, size_t size)
339 {
340         void *ret = kmem_cache_alloc_node(s, gfpflags, node);
341 
342         kasan_kmalloc(s, ret, size);
343         return ret;
344 }
345 #endif /* CONFIG_TRACING */
346 
347 extern void *kmalloc_order(size_t size, gfp_t flags, unsigned int order);
348 
349 #ifdef CONFIG_TRACING
350 extern void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order);
351 #else
352 static __always_inline void *
353 kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
354 {
355         return kmalloc_order(size, flags, order);
356 }
357 #endif
358 
359 static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
360 {
361         unsigned int order = get_order(size);
362         return kmalloc_order_trace(size, flags, order);
363 }
364 
365 /**
366  * kmalloc - allocate memory
367  * @size: how many bytes of memory are required.
368  * @flags: the type of memory to allocate.
369  *
370  * kmalloc is the normal method of allocating memory
371  * for objects smaller than page size in the kernel.
372  *
373  * The @flags argument may be one of:
374  *
375  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
376  *
377  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
378  *
379  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
380  *   For example, use this inside interrupt handlers.
381  *
382  * %GFP_HIGHUSER - Allocate pages from high memory.
383  *
384  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
385  *
386  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
387  *
388  * %GFP_NOWAIT - Allocation will not sleep.
389  *
390  * %__GFP_THISNODE - Allocate node-local memory only.
391  *
392  * %GFP_DMA - Allocation suitable for DMA.
393  *   Should only be used for kmalloc() caches. Otherwise, use a
394  *   slab created with SLAB_DMA.
395  *
396  * Also it is possible to set different flags by OR'ing
397  * in one or more of the following additional @flags:
398  *
399  * %__GFP_COLD - Request cache-cold pages instead of
400  *   trying to return cache-warm pages.
401  *
402  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
403  *
404  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
405  *   (think twice before using).
406  *
407  * %__GFP_NORETRY - If memory is not immediately available,
408  *   then give up at once.
409  *
410  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
411  *
412  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
413  *
414  * There are other flags available as well, but these are not intended
415  * for general use, and so are not documented here. For a full list of
416  * potential flags, always refer to linux/gfp.h.
417  */
418 static __always_inline void *kmalloc(size_t size, gfp_t flags)
419 {
420         if (__builtin_constant_p(size)) {
421                 if (size > KMALLOC_MAX_CACHE_SIZE)
422                         return kmalloc_large(size, flags);
423 #ifndef CONFIG_SLOB
424                 if (!(flags & GFP_DMA)) {
425                         int index = kmalloc_index(size);
426 
427                         if (!index)
428                                 return ZERO_SIZE_PTR;
429 
430                         return kmem_cache_alloc_trace(kmalloc_caches[index],
431                                         flags, size);
432                 }
433 #endif
434         }
435         return __kmalloc(size, flags);
436 }
437 
438 /*
439  * Determine size used for the nth kmalloc cache.
440  * return size or 0 if a kmalloc cache for that
441  * size does not exist
442  */
443 static __always_inline int kmalloc_size(int n)
444 {
445 #ifndef CONFIG_SLOB
446         if (n > 2)
447                 return 1 << n;
448 
449         if (n == 1 && KMALLOC_MIN_SIZE <= 32)
450                 return 96;
451 
452         if (n == 2 && KMALLOC_MIN_SIZE <= 64)
453                 return 192;
454 #endif
455         return 0;
456 }
457 
458 static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
459 {
460 #ifndef CONFIG_SLOB
461         if (__builtin_constant_p(size) &&
462                 size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) {
463                 int i = kmalloc_index(size);
464 
465                 if (!i)
466                         return ZERO_SIZE_PTR;
467 
468                 return kmem_cache_alloc_node_trace(kmalloc_caches[i],
469                                                 flags, node, size);
470         }
471 #endif
472         return __kmalloc_node(size, flags, node);
473 }
474 
475 /*
476  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
477  * Intended for arches that get misalignment faults even for 64 bit integer
478  * aligned buffers.
479  */
480 #ifndef ARCH_SLAB_MINALIGN
481 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
482 #endif
483 
484 struct memcg_cache_array {
485         struct rcu_head rcu;
486         struct kmem_cache *entries[0];
487 };
488 
489 /*
490  * This is the main placeholder for memcg-related information in kmem caches.
491  * Both the root cache and the child caches will have it. For the root cache,
492  * this will hold a dynamically allocated array large enough to hold
493  * information about the currently limited memcgs in the system. To allow the
494  * array to be accessed without taking any locks, on relocation we free the old
495  * version only after a grace period.
496  *
497  * Child caches will hold extra metadata needed for its operation. Fields are:
498  *
499  * @memcg: pointer to the memcg this cache belongs to
500  * @root_cache: pointer to the global, root cache, this cache was derived from
501  *
502  * Both root and child caches of the same kind are linked into a list chained
503  * through @list.
504  */
505 struct memcg_cache_params {
506         bool is_root_cache;
507         struct list_head list;
508         union {
509                 struct memcg_cache_array __rcu *memcg_caches;
510                 struct {
511                         struct mem_cgroup *memcg;
512                         struct kmem_cache *root_cache;
513                 };
514         };
515 };
516 
517 int memcg_update_all_caches(int num_memcgs);
518 
519 /**
520  * kmalloc_array - allocate memory for an array.
521  * @n: number of elements.
522  * @size: element size.
523  * @flags: the type of memory to allocate (see kmalloc).
524  */
525 static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
526 {
527         if (size != 0 && n > SIZE_MAX / size)
528                 return NULL;
529         return __kmalloc(n * size, flags);
530 }
531 
532 /**
533  * kcalloc - allocate memory for an array. The memory is set to zero.
534  * @n: number of elements.
535  * @size: element size.
536  * @flags: the type of memory to allocate (see kmalloc).
537  */
538 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
539 {
540         return kmalloc_array(n, size, flags | __GFP_ZERO);
541 }
542 
543 /*
544  * kmalloc_track_caller is a special version of kmalloc that records the
545  * calling function of the routine calling it for slab leak tracking instead
546  * of just the calling function (confusing, eh?).
547  * It's useful when the call to kmalloc comes from a widely-used standard
548  * allocator where we care about the real place the memory allocation
549  * request comes from.
550  */
551 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
552 #define kmalloc_track_caller(size, flags) \
553         __kmalloc_track_caller(size, flags, _RET_IP_)
554 
555 #ifdef CONFIG_NUMA
556 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
557 #define kmalloc_node_track_caller(size, flags, node) \
558         __kmalloc_node_track_caller(size, flags, node, \
559                         _RET_IP_)
560 
561 #else /* CONFIG_NUMA */
562 
563 #define kmalloc_node_track_caller(size, flags, node) \
564         kmalloc_track_caller(size, flags)
565 
566 #endif /* CONFIG_NUMA */
567 
568 /*
569  * Shortcuts
570  */
571 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
572 {
573         return kmem_cache_alloc(k, flags | __GFP_ZERO);
574 }
575 
576 /**
577  * kzalloc - allocate memory. The memory is set to zero.
578  * @size: how many bytes of memory are required.
579  * @flags: the type of memory to allocate (see kmalloc).
580  */
581 static inline void *kzalloc(size_t size, gfp_t flags)
582 {
583         return kmalloc(size, flags | __GFP_ZERO);
584 }
585 
586 /**
587  * kzalloc_node - allocate zeroed memory from a particular memory node.
588  * @size: how many bytes of memory are required.
589  * @flags: the type of memory to allocate (see kmalloc).
590  * @node: memory node from which to allocate
591  */
592 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
593 {
594         return kmalloc_node(size, flags | __GFP_ZERO, node);
595 }
596 
597 unsigned int kmem_cache_size(struct kmem_cache *s);
598 void __init kmem_cache_init_late(void);
599 
600 #endif  /* _LINUX_SLAB_H */
601 

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