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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_SLAB_DEBUG 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 
108 struct mem_cgroup;
109 /*
110  * struct kmem_cache related prototypes
111  */
112 void __init kmem_cache_init(void);
113 int slab_is_available(void);
114 
115 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
116                         unsigned long,
117                         void (*)(void *));
118 #ifdef CONFIG_MEMCG_KMEM
119 struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *,
120                                            struct kmem_cache *,
121                                            const char *);
122 #endif
123 void kmem_cache_destroy(struct kmem_cache *);
124 int kmem_cache_shrink(struct kmem_cache *);
125 void kmem_cache_free(struct kmem_cache *, void *);
126 
127 /*
128  * Please use this macro to create slab caches. Simply specify the
129  * name of the structure and maybe some flags that are listed above.
130  *
131  * The alignment of the struct determines object alignment. If you
132  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
133  * then the objects will be properly aligned in SMP configurations.
134  */
135 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
136                 sizeof(struct __struct), __alignof__(struct __struct),\
137                 (__flags), NULL)
138 
139 /*
140  * Common kmalloc functions provided by all allocators
141  */
142 void * __must_check __krealloc(const void *, size_t, gfp_t);
143 void * __must_check krealloc(const void *, size_t, gfp_t);
144 void kfree(const void *);
145 void kzfree(const void *);
146 size_t ksize(const void *);
147 
148 /*
149  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
150  * alignment larger than the alignment of a 64-bit integer.
151  * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
152  */
153 #if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
154 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
155 #define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
156 #define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
157 #else
158 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
159 #endif
160 
161 /*
162  * Kmalloc array related definitions
163  */
164 
165 #ifdef CONFIG_SLAB
166 /*
167  * The largest kmalloc size supported by the SLAB allocators is
168  * 32 megabyte (2^25) or the maximum allocatable page order if that is
169  * less than 32 MB.
170  *
171  * WARNING: Its not easy to increase this value since the allocators have
172  * to do various tricks to work around compiler limitations in order to
173  * ensure proper constant folding.
174  */
175 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
176                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
177 #define KMALLOC_SHIFT_MAX       KMALLOC_SHIFT_HIGH
178 #ifndef KMALLOC_SHIFT_LOW
179 #define KMALLOC_SHIFT_LOW       5
180 #endif
181 #endif
182 
183 #ifdef CONFIG_SLUB
184 /*
185  * SLUB directly allocates requests fitting in to an order-1 page
186  * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
187  */
188 #define KMALLOC_SHIFT_HIGH      (PAGE_SHIFT + 1)
189 #define KMALLOC_SHIFT_MAX       (MAX_ORDER + PAGE_SHIFT)
190 #ifndef KMALLOC_SHIFT_LOW
191 #define KMALLOC_SHIFT_LOW       3
192 #endif
193 #endif
194 
195 #ifdef CONFIG_SLOB
196 /*
197  * SLOB passes all requests larger than one page to the page allocator.
198  * No kmalloc array is necessary since objects of different sizes can
199  * be allocated from the same page.
200  */
201 #define KMALLOC_SHIFT_HIGH      PAGE_SHIFT
202 #define KMALLOC_SHIFT_MAX       30
203 #ifndef KMALLOC_SHIFT_LOW
204 #define KMALLOC_SHIFT_LOW       3
205 #endif
206 #endif
207 
208 /* Maximum allocatable size */
209 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_MAX)
210 /* Maximum size for which we actually use a slab cache */
211 #define KMALLOC_MAX_CACHE_SIZE  (1UL << KMALLOC_SHIFT_HIGH)
212 /* Maximum order allocatable via the slab allocagtor */
213 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
214 
215 /*
216  * Kmalloc subsystem.
217  */
218 #ifndef KMALLOC_MIN_SIZE
219 #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
220 #endif
221 
222 /*
223  * This restriction comes from byte sized index implementation.
224  * Page size is normally 2^12 bytes and, in this case, if we want to use
225  * byte sized index which can represent 2^8 entries, the size of the object
226  * should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
227  * If minimum size of kmalloc is less than 16, we use it as minimum object
228  * size and give up to use byte sized index.
229  */
230 #define SLAB_OBJ_MIN_SIZE      (KMALLOC_MIN_SIZE < 16 ? \
231                                (KMALLOC_MIN_SIZE) : 16)
232 
233 #ifndef CONFIG_SLOB
234 extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
235 #ifdef CONFIG_ZONE_DMA
236 extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
237 #endif
238 
239 /*
240  * Figure out which kmalloc slab an allocation of a certain size
241  * belongs to.
242  * 0 = zero alloc
243  * 1 =  65 .. 96 bytes
244  * 2 = 120 .. 192 bytes
245  * n = 2^(n-1) .. 2^n -1
246  */
247 static __always_inline int kmalloc_index(size_t size)
248 {
249         if (!size)
250                 return 0;
251 
252         if (size <= KMALLOC_MIN_SIZE)
253                 return KMALLOC_SHIFT_LOW;
254 
255         if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
256                 return 1;
257         if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
258                 return 2;
259         if (size <=          8) return 3;
260         if (size <=         16) return 4;
261         if (size <=         32) return 5;
262         if (size <=         64) return 6;
263         if (size <=        128) return 7;
264         if (size <=        256) return 8;
265         if (size <=        512) return 9;
266         if (size <=       1024) return 10;
267         if (size <=   2 * 1024) return 11;
268         if (size <=   4 * 1024) return 12;
269         if (size <=   8 * 1024) return 13;
270         if (size <=  16 * 1024) return 14;
271         if (size <=  32 * 1024) return 15;
272         if (size <=  64 * 1024) return 16;
273         if (size <= 128 * 1024) return 17;
274         if (size <= 256 * 1024) return 18;
275         if (size <= 512 * 1024) return 19;
276         if (size <= 1024 * 1024) return 20;
277         if (size <=  2 * 1024 * 1024) return 21;
278         if (size <=  4 * 1024 * 1024) return 22;
279         if (size <=  8 * 1024 * 1024) return 23;
280         if (size <=  16 * 1024 * 1024) return 24;
281         if (size <=  32 * 1024 * 1024) return 25;
282         if (size <=  64 * 1024 * 1024) return 26;
283         BUG();
284 
285         /* Will never be reached. Needed because the compiler may complain */
286         return -1;
287 }
288 #endif /* !CONFIG_SLOB */
289 
290 void *__kmalloc(size_t size, gfp_t flags);
291 void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags);
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         return kmem_cache_alloc(s, flags);
330 }
331 
332 static __always_inline void *
333 kmem_cache_alloc_node_trace(struct kmem_cache *s,
334                               gfp_t gfpflags,
335                               int node, size_t size)
336 {
337         return kmem_cache_alloc_node(s, gfpflags, node);
338 }
339 #endif /* CONFIG_TRACING */
340 
341 extern void *kmalloc_order(size_t size, gfp_t flags, unsigned int order);
342 
343 #ifdef CONFIG_TRACING
344 extern void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order);
345 #else
346 static __always_inline void *
347 kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
348 {
349         return kmalloc_order(size, flags, order);
350 }
351 #endif
352 
353 static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
354 {
355         unsigned int order = get_order(size);
356         return kmalloc_order_trace(size, flags, order);
357 }
358 
359 /**
360  * kmalloc - allocate memory
361  * @size: how many bytes of memory are required.
362  * @flags: the type of memory to allocate.
363  *
364  * kmalloc is the normal method of allocating memory
365  * for objects smaller than page size in the kernel.
366  *
367  * The @flags argument may be one of:
368  *
369  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
370  *
371  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
372  *
373  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
374  *   For example, use this inside interrupt handlers.
375  *
376  * %GFP_HIGHUSER - Allocate pages from high memory.
377  *
378  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
379  *
380  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
381  *
382  * %GFP_NOWAIT - Allocation will not sleep.
383  *
384  * %__GFP_THISNODE - Allocate node-local memory only.
385  *
386  * %GFP_DMA - Allocation suitable for DMA.
387  *   Should only be used for kmalloc() caches. Otherwise, use a
388  *   slab created with SLAB_DMA.
389  *
390  * Also it is possible to set different flags by OR'ing
391  * in one or more of the following additional @flags:
392  *
393  * %__GFP_COLD - Request cache-cold pages instead of
394  *   trying to return cache-warm pages.
395  *
396  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
397  *
398  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
399  *   (think twice before using).
400  *
401  * %__GFP_NORETRY - If memory is not immediately available,
402  *   then give up at once.
403  *
404  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
405  *
406  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
407  *
408  * There are other flags available as well, but these are not intended
409  * for general use, and so are not documented here. For a full list of
410  * potential flags, always refer to linux/gfp.h.
411  */
412 static __always_inline void *kmalloc(size_t size, gfp_t flags)
413 {
414         if (__builtin_constant_p(size)) {
415                 if (size > KMALLOC_MAX_CACHE_SIZE)
416                         return kmalloc_large(size, flags);
417 #ifndef CONFIG_SLOB
418                 if (!(flags & GFP_DMA)) {
419                         int index = kmalloc_index(size);
420 
421                         if (!index)
422                                 return ZERO_SIZE_PTR;
423 
424                         return kmem_cache_alloc_trace(kmalloc_caches[index],
425                                         flags, size);
426                 }
427 #endif
428         }
429         return __kmalloc(size, flags);
430 }
431 
432 /*
433  * Determine size used for the nth kmalloc cache.
434  * return size or 0 if a kmalloc cache for that
435  * size does not exist
436  */
437 static __always_inline int kmalloc_size(int n)
438 {
439 #ifndef CONFIG_SLOB
440         if (n > 2)
441                 return 1 << n;
442 
443         if (n == 1 && KMALLOC_MIN_SIZE <= 32)
444                 return 96;
445 
446         if (n == 2 && KMALLOC_MIN_SIZE <= 64)
447                 return 192;
448 #endif
449         return 0;
450 }
451 
452 static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
453 {
454 #ifndef CONFIG_SLOB
455         if (__builtin_constant_p(size) &&
456                 size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) {
457                 int i = kmalloc_index(size);
458 
459                 if (!i)
460                         return ZERO_SIZE_PTR;
461 
462                 return kmem_cache_alloc_node_trace(kmalloc_caches[i],
463                                                 flags, node, size);
464         }
465 #endif
466         return __kmalloc_node(size, flags, node);
467 }
468 
469 /*
470  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
471  * Intended for arches that get misalignment faults even for 64 bit integer
472  * aligned buffers.
473  */
474 #ifndef ARCH_SLAB_MINALIGN
475 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
476 #endif
477 /*
478  * This is the main placeholder for memcg-related information in kmem caches.
479  * struct kmem_cache will hold a pointer to it, so the memory cost while
480  * disabled is 1 pointer. The runtime cost while enabled, gets bigger than it
481  * would otherwise be if that would be bundled in kmem_cache: we'll need an
482  * extra pointer chase. But the trade off clearly lays in favor of not
483  * penalizing non-users.
484  *
485  * Both the root cache and the child caches will have it. For the root cache,
486  * this will hold a dynamically allocated array large enough to hold
487  * information about the currently limited memcgs in the system. To allow the
488  * array to be accessed without taking any locks, on relocation we free the old
489  * version only after a grace period.
490  *
491  * Child caches will hold extra metadata needed for its operation. Fields are:
492  *
493  * @memcg: pointer to the memcg this cache belongs to
494  * @list: list_head for the list of all caches in this memcg
495  * @root_cache: pointer to the global, root cache, this cache was derived from
496  * @nr_pages: number of pages that belongs to this cache.
497  */
498 struct memcg_cache_params {
499         bool is_root_cache;
500         union {
501                 struct {
502                         struct rcu_head rcu_head;
503                         struct kmem_cache *memcg_caches[0];
504                 };
505                 struct {
506                         struct mem_cgroup *memcg;
507                         struct list_head list;
508                         struct kmem_cache *root_cache;
509                         atomic_t nr_pages;
510                 };
511         };
512 };
513 
514 int memcg_update_all_caches(int num_memcgs);
515 
516 struct seq_file;
517 int cache_show(struct kmem_cache *s, struct seq_file *m);
518 void print_slabinfo_header(struct seq_file *m);
519 
520 /**
521  * kmalloc_array - allocate memory for an array.
522  * @n: number of elements.
523  * @size: element size.
524  * @flags: the type of memory to allocate (see kmalloc).
525  */
526 static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
527 {
528         if (size != 0 && n > SIZE_MAX / size)
529                 return NULL;
530         return __kmalloc(n * size, flags);
531 }
532 
533 /**
534  * kcalloc - allocate memory for an array. The memory is set to zero.
535  * @n: number of elements.
536  * @size: element size.
537  * @flags: the type of memory to allocate (see kmalloc).
538  */
539 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
540 {
541         return kmalloc_array(n, size, flags | __GFP_ZERO);
542 }
543 
544 /*
545  * kmalloc_track_caller is a special version of kmalloc that records the
546  * calling function of the routine calling it for slab leak tracking instead
547  * of just the calling function (confusing, eh?).
548  * It's useful when the call to kmalloc comes from a widely-used standard
549  * allocator where we care about the real place the memory allocation
550  * request comes from.
551  */
552 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
553 #define kmalloc_track_caller(size, flags) \
554         __kmalloc_track_caller(size, flags, _RET_IP_)
555 
556 #ifdef CONFIG_NUMA
557 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
558 #define kmalloc_node_track_caller(size, flags, node) \
559         __kmalloc_node_track_caller(size, flags, node, \
560                         _RET_IP_)
561 
562 #else /* CONFIG_NUMA */
563 
564 #define kmalloc_node_track_caller(size, flags, node) \
565         kmalloc_track_caller(size, flags)
566 
567 #endif /* CONFIG_NUMA */
568 
569 /*
570  * Shortcuts
571  */
572 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
573 {
574         return kmem_cache_alloc(k, flags | __GFP_ZERO);
575 }
576 
577 /**
578  * kzalloc - allocate memory. The memory is set to zero.
579  * @size: how many bytes of memory are required.
580  * @flags: the type of memory to allocate (see kmalloc).
581  */
582 static inline void *kzalloc(size_t size, gfp_t flags)
583 {
584         return kmalloc(size, flags | __GFP_ZERO);
585 }
586 
587 /**
588  * kzalloc_node - allocate zeroed memory from a particular memory node.
589  * @size: how many bytes of memory are required.
590  * @flags: the type of memory to allocate (see kmalloc).
591  * @node: memory node from which to allocate
592  */
593 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
594 {
595         return kmalloc_node(size, flags | __GFP_ZERO, node);
596 }
597 
598 unsigned int kmem_cache_size(struct kmem_cache *s);
599 void __init kmem_cache_init_late(void);
600 
601 #endif  /* _LINUX_SLAB_H */
602 

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