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Linux/mm/slab_common.c

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  1 /*
  2  * Slab allocator functions that are independent of the allocator strategy
  3  *
  4  * (C) 2012 Christoph Lameter <cl@linux.com>
  5  */
  6 #include <linux/slab.h>
  7 
  8 #include <linux/mm.h>
  9 #include <linux/poison.h>
 10 #include <linux/interrupt.h>
 11 #include <linux/memory.h>
 12 #include <linux/compiler.h>
 13 #include <linux/module.h>
 14 #include <linux/cpu.h>
 15 #include <linux/uaccess.h>
 16 #include <linux/seq_file.h>
 17 #include <linux/proc_fs.h>
 18 #include <asm/cacheflush.h>
 19 #include <asm/tlbflush.h>
 20 #include <asm/page.h>
 21 #include <linux/memcontrol.h>
 22 
 23 #define CREATE_TRACE_POINTS
 24 #include <trace/events/kmem.h>
 25 
 26 #include "slab.h"
 27 
 28 enum slab_state slab_state;
 29 LIST_HEAD(slab_caches);
 30 DEFINE_MUTEX(slab_mutex);
 31 struct kmem_cache *kmem_cache;
 32 
 33 /*
 34  * Set of flags that will prevent slab merging
 35  */
 36 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
 37                 SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
 38                 SLAB_FAILSLAB)
 39 
 40 #define SLAB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
 41                 SLAB_CACHE_DMA | SLAB_NOTRACK)
 42 
 43 /*
 44  * Merge control. If this is set then no merging of slab caches will occur.
 45  * (Could be removed. This was introduced to pacify the merge skeptics.)
 46  */
 47 static int slab_nomerge;
 48 
 49 static int __init setup_slab_nomerge(char *str)
 50 {
 51         slab_nomerge = 1;
 52         return 1;
 53 }
 54 
 55 #ifdef CONFIG_SLUB
 56 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
 57 #endif
 58 
 59 __setup("slab_nomerge", setup_slab_nomerge);
 60 
 61 /*
 62  * Determine the size of a slab object
 63  */
 64 unsigned int kmem_cache_size(struct kmem_cache *s)
 65 {
 66         return s->object_size;
 67 }
 68 EXPORT_SYMBOL(kmem_cache_size);
 69 
 70 #ifdef CONFIG_DEBUG_VM
 71 static int kmem_cache_sanity_check(const char *name, size_t size)
 72 {
 73         struct kmem_cache *s = NULL;
 74 
 75         if (!name || in_interrupt() || size < sizeof(void *) ||
 76                 size > KMALLOC_MAX_SIZE) {
 77                 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
 78                 return -EINVAL;
 79         }
 80 
 81         list_for_each_entry(s, &slab_caches, list) {
 82                 char tmp;
 83                 int res;
 84 
 85                 /*
 86                  * This happens when the module gets unloaded and doesn't
 87                  * destroy its slab cache and no-one else reuses the vmalloc
 88                  * area of the module.  Print a warning.
 89                  */
 90                 res = probe_kernel_address(s->name, tmp);
 91                 if (res) {
 92                         pr_err("Slab cache with size %d has lost its name\n",
 93                                s->object_size);
 94                         continue;
 95                 }
 96         }
 97 
 98         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
 99         return 0;
100 }
101 #else
102 static inline int kmem_cache_sanity_check(const char *name, size_t size)
103 {
104         return 0;
105 }
106 #endif
107 
108 #ifdef CONFIG_MEMCG_KMEM
109 static int memcg_alloc_cache_params(struct mem_cgroup *memcg,
110                 struct kmem_cache *s, struct kmem_cache *root_cache)
111 {
112         size_t size;
113 
114         if (!memcg_kmem_enabled())
115                 return 0;
116 
117         if (!memcg) {
118                 size = offsetof(struct memcg_cache_params, memcg_caches);
119                 size += memcg_limited_groups_array_size * sizeof(void *);
120         } else
121                 size = sizeof(struct memcg_cache_params);
122 
123         s->memcg_params = kzalloc(size, GFP_KERNEL);
124         if (!s->memcg_params)
125                 return -ENOMEM;
126 
127         if (memcg) {
128                 s->memcg_params->memcg = memcg;
129                 s->memcg_params->root_cache = root_cache;
130         } else
131                 s->memcg_params->is_root_cache = true;
132 
133         return 0;
134 }
135 
136 static void memcg_free_cache_params(struct kmem_cache *s)
137 {
138         kfree(s->memcg_params);
139 }
140 
141 static int memcg_update_cache_params(struct kmem_cache *s, int num_memcgs)
142 {
143         int size;
144         struct memcg_cache_params *new_params, *cur_params;
145 
146         BUG_ON(!is_root_cache(s));
147 
148         size = offsetof(struct memcg_cache_params, memcg_caches);
149         size += num_memcgs * sizeof(void *);
150 
151         new_params = kzalloc(size, GFP_KERNEL);
152         if (!new_params)
153                 return -ENOMEM;
154 
155         cur_params = s->memcg_params;
156         memcpy(new_params->memcg_caches, cur_params->memcg_caches,
157                memcg_limited_groups_array_size * sizeof(void *));
158 
159         new_params->is_root_cache = true;
160 
161         rcu_assign_pointer(s->memcg_params, new_params);
162         if (cur_params)
163                 kfree_rcu(cur_params, rcu_head);
164 
165         return 0;
166 }
167 
168 int memcg_update_all_caches(int num_memcgs)
169 {
170         struct kmem_cache *s;
171         int ret = 0;
172         mutex_lock(&slab_mutex);
173 
174         list_for_each_entry(s, &slab_caches, list) {
175                 if (!is_root_cache(s))
176                         continue;
177 
178                 ret = memcg_update_cache_params(s, num_memcgs);
179                 /*
180                  * Instead of freeing the memory, we'll just leave the caches
181                  * up to this point in an updated state.
182                  */
183                 if (ret)
184                         goto out;
185         }
186 
187         memcg_update_array_size(num_memcgs);
188 out:
189         mutex_unlock(&slab_mutex);
190         return ret;
191 }
192 #else
193 static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,
194                 struct kmem_cache *s, struct kmem_cache *root_cache)
195 {
196         return 0;
197 }
198 
199 static inline void memcg_free_cache_params(struct kmem_cache *s)
200 {
201 }
202 #endif /* CONFIG_MEMCG_KMEM */
203 
204 /*
205  * Find a mergeable slab cache
206  */
207 int slab_unmergeable(struct kmem_cache *s)
208 {
209         if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
210                 return 1;
211 
212         if (!is_root_cache(s))
213                 return 1;
214 
215         if (s->ctor)
216                 return 1;
217 
218         /*
219          * We may have set a slab to be unmergeable during bootstrap.
220          */
221         if (s->refcount < 0)
222                 return 1;
223 
224         return 0;
225 }
226 
227 struct kmem_cache *find_mergeable(size_t size, size_t align,
228                 unsigned long flags, const char *name, void (*ctor)(void *))
229 {
230         struct kmem_cache *s;
231 
232         if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
233                 return NULL;
234 
235         if (ctor)
236                 return NULL;
237 
238         size = ALIGN(size, sizeof(void *));
239         align = calculate_alignment(flags, align, size);
240         size = ALIGN(size, align);
241         flags = kmem_cache_flags(size, flags, name, NULL);
242 
243         list_for_each_entry(s, &slab_caches, list) {
244                 if (slab_unmergeable(s))
245                         continue;
246 
247                 if (size > s->size)
248                         continue;
249 
250                 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
251                         continue;
252                 /*
253                  * Check if alignment is compatible.
254                  * Courtesy of Adrian Drzewiecki
255                  */
256                 if ((s->size & ~(align - 1)) != s->size)
257                         continue;
258 
259                 if (s->size - size >= sizeof(void *))
260                         continue;
261 
262                 if (IS_ENABLED(CONFIG_SLAB) && align &&
263                         (align > s->align || s->align % align))
264                         continue;
265 
266                 return s;
267         }
268         return NULL;
269 }
270 
271 /*
272  * Figure out what the alignment of the objects will be given a set of
273  * flags, a user specified alignment and the size of the objects.
274  */
275 unsigned long calculate_alignment(unsigned long flags,
276                 unsigned long align, unsigned long size)
277 {
278         /*
279          * If the user wants hardware cache aligned objects then follow that
280          * suggestion if the object is sufficiently large.
281          *
282          * The hardware cache alignment cannot override the specified
283          * alignment though. If that is greater then use it.
284          */
285         if (flags & SLAB_HWCACHE_ALIGN) {
286                 unsigned long ralign = cache_line_size();
287                 while (size <= ralign / 2)
288                         ralign /= 2;
289                 align = max(align, ralign);
290         }
291 
292         if (align < ARCH_SLAB_MINALIGN)
293                 align = ARCH_SLAB_MINALIGN;
294 
295         return ALIGN(align, sizeof(void *));
296 }
297 
298 static struct kmem_cache *
299 do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
300                      unsigned long flags, void (*ctor)(void *),
301                      struct mem_cgroup *memcg, struct kmem_cache *root_cache)
302 {
303         struct kmem_cache *s;
304         int err;
305 
306         err = -ENOMEM;
307         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
308         if (!s)
309                 goto out;
310 
311         s->name = name;
312         s->object_size = object_size;
313         s->size = size;
314         s->align = align;
315         s->ctor = ctor;
316 
317         err = memcg_alloc_cache_params(memcg, s, root_cache);
318         if (err)
319                 goto out_free_cache;
320 
321         err = __kmem_cache_create(s, flags);
322         if (err)
323                 goto out_free_cache;
324 
325         s->refcount = 1;
326         list_add(&s->list, &slab_caches);
327 out:
328         if (err)
329                 return ERR_PTR(err);
330         return s;
331 
332 out_free_cache:
333         memcg_free_cache_params(s);
334         kfree(s);
335         goto out;
336 }
337 
338 /*
339  * kmem_cache_create - Create a cache.
340  * @name: A string which is used in /proc/slabinfo to identify this cache.
341  * @size: The size of objects to be created in this cache.
342  * @align: The required alignment for the objects.
343  * @flags: SLAB flags
344  * @ctor: A constructor for the objects.
345  *
346  * Returns a ptr to the cache on success, NULL on failure.
347  * Cannot be called within a interrupt, but can be interrupted.
348  * The @ctor is run when new pages are allocated by the cache.
349  *
350  * The flags are
351  *
352  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
353  * to catch references to uninitialised memory.
354  *
355  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
356  * for buffer overruns.
357  *
358  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
359  * cacheline.  This can be beneficial if you're counting cycles as closely
360  * as davem.
361  */
362 struct kmem_cache *
363 kmem_cache_create(const char *name, size_t size, size_t align,
364                   unsigned long flags, void (*ctor)(void *))
365 {
366         struct kmem_cache *s;
367         char *cache_name;
368         int err;
369 
370         get_online_cpus();
371         get_online_mems();
372 
373         mutex_lock(&slab_mutex);
374 
375         err = kmem_cache_sanity_check(name, size);
376         if (err) {
377                 s = NULL;       /* suppress uninit var warning */
378                 goto out_unlock;
379         }
380 
381         /*
382          * Some allocators will constraint the set of valid flags to a subset
383          * of all flags. We expect them to define CACHE_CREATE_MASK in this
384          * case, and we'll just provide them with a sanitized version of the
385          * passed flags.
386          */
387         flags &= CACHE_CREATE_MASK;
388 
389         s = __kmem_cache_alias(name, size, align, flags, ctor);
390         if (s)
391                 goto out_unlock;
392 
393         cache_name = kstrdup(name, GFP_KERNEL);
394         if (!cache_name) {
395                 err = -ENOMEM;
396                 goto out_unlock;
397         }
398 
399         s = do_kmem_cache_create(cache_name, size, size,
400                                  calculate_alignment(flags, align, size),
401                                  flags, ctor, NULL, NULL);
402         if (IS_ERR(s)) {
403                 err = PTR_ERR(s);
404                 kfree(cache_name);
405         }
406 
407 out_unlock:
408         mutex_unlock(&slab_mutex);
409 
410         put_online_mems();
411         put_online_cpus();
412 
413         if (err) {
414                 if (flags & SLAB_PANIC)
415                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
416                                 name, err);
417                 else {
418                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
419                                 name, err);
420                         dump_stack();
421                 }
422                 return NULL;
423         }
424         return s;
425 }
426 EXPORT_SYMBOL(kmem_cache_create);
427 
428 #ifdef CONFIG_MEMCG_KMEM
429 /*
430  * memcg_create_kmem_cache - Create a cache for a memory cgroup.
431  * @memcg: The memory cgroup the new cache is for.
432  * @root_cache: The parent of the new cache.
433  * @memcg_name: The name of the memory cgroup (used for naming the new cache).
434  *
435  * This function attempts to create a kmem cache that will serve allocation
436  * requests going from @memcg to @root_cache. The new cache inherits properties
437  * from its parent.
438  */
439 struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
440                                            struct kmem_cache *root_cache,
441                                            const char *memcg_name)
442 {
443         struct kmem_cache *s = NULL;
444         char *cache_name;
445 
446         get_online_cpus();
447         get_online_mems();
448 
449         mutex_lock(&slab_mutex);
450 
451         cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
452                                memcg_cache_id(memcg), memcg_name);
453         if (!cache_name)
454                 goto out_unlock;
455 
456         s = do_kmem_cache_create(cache_name, root_cache->object_size,
457                                  root_cache->size, root_cache->align,
458                                  root_cache->flags, root_cache->ctor,
459                                  memcg, root_cache);
460         if (IS_ERR(s)) {
461                 kfree(cache_name);
462                 s = NULL;
463         }
464 
465 out_unlock:
466         mutex_unlock(&slab_mutex);
467 
468         put_online_mems();
469         put_online_cpus();
470 
471         return s;
472 }
473 
474 static int memcg_cleanup_cache_params(struct kmem_cache *s)
475 {
476         int rc;
477 
478         if (!s->memcg_params ||
479             !s->memcg_params->is_root_cache)
480                 return 0;
481 
482         mutex_unlock(&slab_mutex);
483         rc = __memcg_cleanup_cache_params(s);
484         mutex_lock(&slab_mutex);
485 
486         return rc;
487 }
488 #else
489 static int memcg_cleanup_cache_params(struct kmem_cache *s)
490 {
491         return 0;
492 }
493 #endif /* CONFIG_MEMCG_KMEM */
494 
495 void slab_kmem_cache_release(struct kmem_cache *s)
496 {
497         kfree(s->name);
498         kmem_cache_free(kmem_cache, s);
499 }
500 
501 void kmem_cache_destroy(struct kmem_cache *s)
502 {
503         get_online_cpus();
504         get_online_mems();
505 
506         mutex_lock(&slab_mutex);
507 
508         s->refcount--;
509         if (s->refcount)
510                 goto out_unlock;
511 
512         if (memcg_cleanup_cache_params(s) != 0)
513                 goto out_unlock;
514 
515         if (__kmem_cache_shutdown(s) != 0) {
516                 printk(KERN_ERR "kmem_cache_destroy %s: "
517                        "Slab cache still has objects\n", s->name);
518                 dump_stack();
519                 goto out_unlock;
520         }
521 
522         list_del(&s->list);
523 
524         mutex_unlock(&slab_mutex);
525         if (s->flags & SLAB_DESTROY_BY_RCU)
526                 rcu_barrier();
527 
528         memcg_free_cache_params(s);
529 #ifdef SLAB_SUPPORTS_SYSFS
530         sysfs_slab_remove(s);
531 #else
532         slab_kmem_cache_release(s);
533 #endif
534         goto out;
535 
536 out_unlock:
537         mutex_unlock(&slab_mutex);
538 out:
539         put_online_mems();
540         put_online_cpus();
541 }
542 EXPORT_SYMBOL(kmem_cache_destroy);
543 
544 /**
545  * kmem_cache_shrink - Shrink a cache.
546  * @cachep: The cache to shrink.
547  *
548  * Releases as many slabs as possible for a cache.
549  * To help debugging, a zero exit status indicates all slabs were released.
550  */
551 int kmem_cache_shrink(struct kmem_cache *cachep)
552 {
553         int ret;
554 
555         get_online_cpus();
556         get_online_mems();
557         ret = __kmem_cache_shrink(cachep);
558         put_online_mems();
559         put_online_cpus();
560         return ret;
561 }
562 EXPORT_SYMBOL(kmem_cache_shrink);
563 
564 int slab_is_available(void)
565 {
566         return slab_state >= UP;
567 }
568 
569 #ifndef CONFIG_SLOB
570 /* Create a cache during boot when no slab services are available yet */
571 void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
572                 unsigned long flags)
573 {
574         int err;
575 
576         s->name = name;
577         s->size = s->object_size = size;
578         s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
579         err = __kmem_cache_create(s, flags);
580 
581         if (err)
582                 panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
583                                         name, size, err);
584 
585         s->refcount = -1;       /* Exempt from merging for now */
586 }
587 
588 struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
589                                 unsigned long flags)
590 {
591         struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
592 
593         if (!s)
594                 panic("Out of memory when creating slab %s\n", name);
595 
596         create_boot_cache(s, name, size, flags);
597         list_add(&s->list, &slab_caches);
598         s->refcount = 1;
599         return s;
600 }
601 
602 struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
603 EXPORT_SYMBOL(kmalloc_caches);
604 
605 #ifdef CONFIG_ZONE_DMA
606 struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
607 EXPORT_SYMBOL(kmalloc_dma_caches);
608 #endif
609 
610 /*
611  * Conversion table for small slabs sizes / 8 to the index in the
612  * kmalloc array. This is necessary for slabs < 192 since we have non power
613  * of two cache sizes there. The size of larger slabs can be determined using
614  * fls.
615  */
616 static s8 size_index[24] = {
617         3,      /* 8 */
618         4,      /* 16 */
619         5,      /* 24 */
620         5,      /* 32 */
621         6,      /* 40 */
622         6,      /* 48 */
623         6,      /* 56 */
624         6,      /* 64 */
625         1,      /* 72 */
626         1,      /* 80 */
627         1,      /* 88 */
628         1,      /* 96 */
629         7,      /* 104 */
630         7,      /* 112 */
631         7,      /* 120 */
632         7,      /* 128 */
633         2,      /* 136 */
634         2,      /* 144 */
635         2,      /* 152 */
636         2,      /* 160 */
637         2,      /* 168 */
638         2,      /* 176 */
639         2,      /* 184 */
640         2       /* 192 */
641 };
642 
643 static inline int size_index_elem(size_t bytes)
644 {
645         return (bytes - 1) / 8;
646 }
647 
648 /*
649  * Find the kmem_cache structure that serves a given size of
650  * allocation
651  */
652 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
653 {
654         int index;
655 
656         if (unlikely(size > KMALLOC_MAX_SIZE)) {
657                 WARN_ON_ONCE(!(flags & __GFP_NOWARN));
658                 return NULL;
659         }
660 
661         if (size <= 192) {
662                 if (!size)
663                         return ZERO_SIZE_PTR;
664 
665                 index = size_index[size_index_elem(size)];
666         } else
667                 index = fls(size - 1);
668 
669 #ifdef CONFIG_ZONE_DMA
670         if (unlikely((flags & GFP_DMA)))
671                 return kmalloc_dma_caches[index];
672 
673 #endif
674         return kmalloc_caches[index];
675 }
676 
677 /*
678  * Create the kmalloc array. Some of the regular kmalloc arrays
679  * may already have been created because they were needed to
680  * enable allocations for slab creation.
681  */
682 void __init create_kmalloc_caches(unsigned long flags)
683 {
684         int i;
685 
686         /*
687          * Patch up the size_index table if we have strange large alignment
688          * requirements for the kmalloc array. This is only the case for
689          * MIPS it seems. The standard arches will not generate any code here.
690          *
691          * Largest permitted alignment is 256 bytes due to the way we
692          * handle the index determination for the smaller caches.
693          *
694          * Make sure that nothing crazy happens if someone starts tinkering
695          * around with ARCH_KMALLOC_MINALIGN
696          */
697         BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
698                 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
699 
700         for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
701                 int elem = size_index_elem(i);
702 
703                 if (elem >= ARRAY_SIZE(size_index))
704                         break;
705                 size_index[elem] = KMALLOC_SHIFT_LOW;
706         }
707 
708         if (KMALLOC_MIN_SIZE >= 64) {
709                 /*
710                  * The 96 byte size cache is not used if the alignment
711                  * is 64 byte.
712                  */
713                 for (i = 64 + 8; i <= 96; i += 8)
714                         size_index[size_index_elem(i)] = 7;
715 
716         }
717 
718         if (KMALLOC_MIN_SIZE >= 128) {
719                 /*
720                  * The 192 byte sized cache is not used if the alignment
721                  * is 128 byte. Redirect kmalloc to use the 256 byte cache
722                  * instead.
723                  */
724                 for (i = 128 + 8; i <= 192; i += 8)
725                         size_index[size_index_elem(i)] = 8;
726         }
727         for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
728                 if (!kmalloc_caches[i]) {
729                         kmalloc_caches[i] = create_kmalloc_cache(NULL,
730                                                         1 << i, flags);
731                 }
732 
733                 /*
734                  * Caches that are not of the two-to-the-power-of size.
735                  * These have to be created immediately after the
736                  * earlier power of two caches
737                  */
738                 if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
739                         kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);
740 
741                 if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
742                         kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);
743         }
744 
745         /* Kmalloc array is now usable */
746         slab_state = UP;
747 
748         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
749                 struct kmem_cache *s = kmalloc_caches[i];
750                 char *n;
751 
752                 if (s) {
753                         n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i));
754 
755                         BUG_ON(!n);
756                         s->name = n;
757                 }
758         }
759 
760 #ifdef CONFIG_ZONE_DMA
761         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
762                 struct kmem_cache *s = kmalloc_caches[i];
763 
764                 if (s) {
765                         int size = kmalloc_size(i);
766                         char *n = kasprintf(GFP_NOWAIT,
767                                  "dma-kmalloc-%d", size);
768 
769                         BUG_ON(!n);
770                         kmalloc_dma_caches[i] = create_kmalloc_cache(n,
771                                 size, SLAB_CACHE_DMA | flags);
772                 }
773         }
774 #endif
775 }
776 #endif /* !CONFIG_SLOB */
777 
778 /*
779  * To avoid unnecessary overhead, we pass through large allocation requests
780  * directly to the page allocator. We use __GFP_COMP, because we will need to
781  * know the allocation order to free the pages properly in kfree.
782  */
783 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
784 {
785         void *ret;
786         struct page *page;
787 
788         flags |= __GFP_COMP;
789         page = alloc_kmem_pages(flags, order);
790         ret = page ? page_address(page) : NULL;
791         kmemleak_alloc(ret, size, 1, flags);
792         return ret;
793 }
794 EXPORT_SYMBOL(kmalloc_order);
795 
796 #ifdef CONFIG_TRACING
797 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
798 {
799         void *ret = kmalloc_order(size, flags, order);
800         trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
801         return ret;
802 }
803 EXPORT_SYMBOL(kmalloc_order_trace);
804 #endif
805 
806 #ifdef CONFIG_SLABINFO
807 
808 #ifdef CONFIG_SLAB
809 #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
810 #else
811 #define SLABINFO_RIGHTS S_IRUSR
812 #endif
813 
814 void print_slabinfo_header(struct seq_file *m)
815 {
816         /*
817          * Output format version, so at least we can change it
818          * without _too_ many complaints.
819          */
820 #ifdef CONFIG_DEBUG_SLAB
821         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
822 #else
823         seq_puts(m, "slabinfo - version: 2.1\n");
824 #endif
825         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
826                  "<objperslab> <pagesperslab>");
827         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
828         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
829 #ifdef CONFIG_DEBUG_SLAB
830         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
831                  "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
832         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
833 #endif
834         seq_putc(m, '\n');
835 }
836 
837 static void *s_start(struct seq_file *m, loff_t *pos)
838 {
839         loff_t n = *pos;
840 
841         mutex_lock(&slab_mutex);
842         if (!n)
843                 print_slabinfo_header(m);
844 
845         return seq_list_start(&slab_caches, *pos);
846 }
847 
848 void *slab_next(struct seq_file *m, void *p, loff_t *pos)
849 {
850         return seq_list_next(p, &slab_caches, pos);
851 }
852 
853 void slab_stop(struct seq_file *m, void *p)
854 {
855         mutex_unlock(&slab_mutex);
856 }
857 
858 static void
859 memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
860 {
861         struct kmem_cache *c;
862         struct slabinfo sinfo;
863         int i;
864 
865         if (!is_root_cache(s))
866                 return;
867 
868         for_each_memcg_cache_index(i) {
869                 c = cache_from_memcg_idx(s, i);
870                 if (!c)
871                         continue;
872 
873                 memset(&sinfo, 0, sizeof(sinfo));
874                 get_slabinfo(c, &sinfo);
875 
876                 info->active_slabs += sinfo.active_slabs;
877                 info->num_slabs += sinfo.num_slabs;
878                 info->shared_avail += sinfo.shared_avail;
879                 info->active_objs += sinfo.active_objs;
880                 info->num_objs += sinfo.num_objs;
881         }
882 }
883 
884 int cache_show(struct kmem_cache *s, struct seq_file *m)
885 {
886         struct slabinfo sinfo;
887 
888         memset(&sinfo, 0, sizeof(sinfo));
889         get_slabinfo(s, &sinfo);
890 
891         memcg_accumulate_slabinfo(s, &sinfo);
892 
893         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
894                    cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
895                    sinfo.objects_per_slab, (1 << sinfo.cache_order));
896 
897         seq_printf(m, " : tunables %4u %4u %4u",
898                    sinfo.limit, sinfo.batchcount, sinfo.shared);
899         seq_printf(m, " : slabdata %6lu %6lu %6lu",
900                    sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
901         slabinfo_show_stats(m, s);
902         seq_putc(m, '\n');
903         return 0;
904 }
905 
906 static int s_show(struct seq_file *m, void *p)
907 {
908         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
909 
910         if (!is_root_cache(s))
911                 return 0;
912         return cache_show(s, m);
913 }
914 
915 /*
916  * slabinfo_op - iterator that generates /proc/slabinfo
917  *
918  * Output layout:
919  * cache-name
920  * num-active-objs
921  * total-objs
922  * object size
923  * num-active-slabs
924  * total-slabs
925  * num-pages-per-slab
926  * + further values on SMP and with statistics enabled
927  */
928 static const struct seq_operations slabinfo_op = {
929         .start = s_start,
930         .next = slab_next,
931         .stop = slab_stop,
932         .show = s_show,
933 };
934 
935 static int slabinfo_open(struct inode *inode, struct file *file)
936 {
937         return seq_open(file, &slabinfo_op);
938 }
939 
940 static const struct file_operations proc_slabinfo_operations = {
941         .open           = slabinfo_open,
942         .read           = seq_read,
943         .write          = slabinfo_write,
944         .llseek         = seq_lseek,
945         .release        = seq_release,
946 };
947 
948 static int __init slab_proc_init(void)
949 {
950         proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
951                                                 &proc_slabinfo_operations);
952         return 0;
953 }
954 module_init(slab_proc_init);
955 #endif /* CONFIG_SLABINFO */
956 
957 static __always_inline void *__do_krealloc(const void *p, size_t new_size,
958                                            gfp_t flags)
959 {
960         void *ret;
961         size_t ks = 0;
962 
963         if (p)
964                 ks = ksize(p);
965 
966         if (ks >= new_size)
967                 return (void *)p;
968 
969         ret = kmalloc_track_caller(new_size, flags);
970         if (ret && p)
971                 memcpy(ret, p, ks);
972 
973         return ret;
974 }
975 
976 /**
977  * __krealloc - like krealloc() but don't free @p.
978  * @p: object to reallocate memory for.
979  * @new_size: how many bytes of memory are required.
980  * @flags: the type of memory to allocate.
981  *
982  * This function is like krealloc() except it never frees the originally
983  * allocated buffer. Use this if you don't want to free the buffer immediately
984  * like, for example, with RCU.
985  */
986 void *__krealloc(const void *p, size_t new_size, gfp_t flags)
987 {
988         if (unlikely(!new_size))
989                 return ZERO_SIZE_PTR;
990 
991         return __do_krealloc(p, new_size, flags);
992 
993 }
994 EXPORT_SYMBOL(__krealloc);
995 
996 /**
997  * krealloc - reallocate memory. The contents will remain unchanged.
998  * @p: object to reallocate memory for.
999  * @new_size: how many bytes of memory are required.
1000  * @flags: the type of memory to allocate.
1001  *
1002  * The contents of the object pointed to are preserved up to the
1003  * lesser of the new and old sizes.  If @p is %NULL, krealloc()
1004  * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
1005  * %NULL pointer, the object pointed to is freed.
1006  */
1007 void *krealloc(const void *p, size_t new_size, gfp_t flags)
1008 {
1009         void *ret;
1010 
1011         if (unlikely(!new_size)) {
1012                 kfree(p);
1013                 return ZERO_SIZE_PTR;
1014         }
1015 
1016         ret = __do_krealloc(p, new_size, flags);
1017         if (ret && p != ret)
1018                 kfree(p);
1019 
1020         return ret;
1021 }
1022 EXPORT_SYMBOL(krealloc);
1023 
1024 /**
1025  * kzfree - like kfree but zero memory
1026  * @p: object to free memory of
1027  *
1028  * The memory of the object @p points to is zeroed before freed.
1029  * If @p is %NULL, kzfree() does nothing.
1030  *
1031  * Note: this function zeroes the whole allocated buffer which can be a good
1032  * deal bigger than the requested buffer size passed to kmalloc(). So be
1033  * careful when using this function in performance sensitive code.
1034  */
1035 void kzfree(const void *p)
1036 {
1037         size_t ks;
1038         void *mem = (void *)p;
1039 
1040         if (unlikely(ZERO_OR_NULL_PTR(mem)))
1041                 return;
1042         ks = ksize(mem);
1043         memset(mem, 0, ks);
1044         kfree(mem);
1045 }
1046 EXPORT_SYMBOL(kzfree);
1047 
1048 /* Tracepoints definitions. */
1049 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1050 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1051 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
1052 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
1053 EXPORT_TRACEPOINT_SYMBOL(kfree);
1054 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1055 

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