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Linux/mm/slab_common.c

  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 | SLAB_KASAN)
 39 
 40 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
 41                          SLAB_NOTRACK | SLAB_ACCOUNT)
 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 void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
109 {
110         size_t i;
111 
112         for (i = 0; i < nr; i++) {
113                 if (s)
114                         kmem_cache_free(s, p[i]);
115                 else
116                         kfree(p[i]);
117         }
118 }
119 
120 int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
121                                                                 void **p)
122 {
123         size_t i;
124 
125         for (i = 0; i < nr; i++) {
126                 void *x = p[i] = kmem_cache_alloc(s, flags);
127                 if (!x) {
128                         __kmem_cache_free_bulk(s, i, p);
129                         return 0;
130                 }
131         }
132         return i;
133 }
134 
135 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
136 void slab_init_memcg_params(struct kmem_cache *s)
137 {
138         s->memcg_params.is_root_cache = true;
139         INIT_LIST_HEAD(&s->memcg_params.list);
140         RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
141 }
142 
143 static int init_memcg_params(struct kmem_cache *s,
144                 struct mem_cgroup *memcg, struct kmem_cache *root_cache)
145 {
146         struct memcg_cache_array *arr;
147 
148         if (memcg) {
149                 s->memcg_params.is_root_cache = false;
150                 s->memcg_params.memcg = memcg;
151                 s->memcg_params.root_cache = root_cache;
152                 return 0;
153         }
154 
155         slab_init_memcg_params(s);
156 
157         if (!memcg_nr_cache_ids)
158                 return 0;
159 
160         arr = kzalloc(sizeof(struct memcg_cache_array) +
161                       memcg_nr_cache_ids * sizeof(void *),
162                       GFP_KERNEL);
163         if (!arr)
164                 return -ENOMEM;
165 
166         RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);
167         return 0;
168 }
169 
170 static void destroy_memcg_params(struct kmem_cache *s)
171 {
172         if (is_root_cache(s))
173                 kfree(rcu_access_pointer(s->memcg_params.memcg_caches));
174 }
175 
176 static int update_memcg_params(struct kmem_cache *s, int new_array_size)
177 {
178         struct memcg_cache_array *old, *new;
179 
180         if (!is_root_cache(s))
181                 return 0;
182 
183         new = kzalloc(sizeof(struct memcg_cache_array) +
184                       new_array_size * sizeof(void *), GFP_KERNEL);
185         if (!new)
186                 return -ENOMEM;
187 
188         old = rcu_dereference_protected(s->memcg_params.memcg_caches,
189                                         lockdep_is_held(&slab_mutex));
190         if (old)
191                 memcpy(new->entries, old->entries,
192                        memcg_nr_cache_ids * sizeof(void *));
193 
194         rcu_assign_pointer(s->memcg_params.memcg_caches, new);
195         if (old)
196                 kfree_rcu(old, rcu);
197         return 0;
198 }
199 
200 int memcg_update_all_caches(int num_memcgs)
201 {
202         struct kmem_cache *s;
203         int ret = 0;
204 
205         mutex_lock(&slab_mutex);
206         list_for_each_entry(s, &slab_caches, list) {
207                 ret = update_memcg_params(s, num_memcgs);
208                 /*
209                  * Instead of freeing the memory, we'll just leave the caches
210                  * up to this point in an updated state.
211                  */
212                 if (ret)
213                         break;
214         }
215         mutex_unlock(&slab_mutex);
216         return ret;
217 }
218 #else
219 static inline int init_memcg_params(struct kmem_cache *s,
220                 struct mem_cgroup *memcg, struct kmem_cache *root_cache)
221 {
222         return 0;
223 }
224 
225 static inline void destroy_memcg_params(struct kmem_cache *s)
226 {
227 }
228 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */
229 
230 /*
231  * Find a mergeable slab cache
232  */
233 int slab_unmergeable(struct kmem_cache *s)
234 {
235         if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
236                 return 1;
237 
238         if (!is_root_cache(s))
239                 return 1;
240 
241         if (s->ctor)
242                 return 1;
243 
244         /*
245          * We may have set a slab to be unmergeable during bootstrap.
246          */
247         if (s->refcount < 0)
248                 return 1;
249 
250         return 0;
251 }
252 
253 struct kmem_cache *find_mergeable(size_t size, size_t align,
254                 unsigned long flags, const char *name, void (*ctor)(void *))
255 {
256         struct kmem_cache *s;
257 
258         if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
259                 return NULL;
260 
261         if (ctor)
262                 return NULL;
263 
264         size = ALIGN(size, sizeof(void *));
265         align = calculate_alignment(flags, align, size);
266         size = ALIGN(size, align);
267         flags = kmem_cache_flags(size, flags, name, NULL);
268 
269         list_for_each_entry_reverse(s, &slab_caches, list) {
270                 if (slab_unmergeable(s))
271                         continue;
272 
273                 if (size > s->size)
274                         continue;
275 
276                 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
277                         continue;
278                 /*
279                  * Check if alignment is compatible.
280                  * Courtesy of Adrian Drzewiecki
281                  */
282                 if ((s->size & ~(align - 1)) != s->size)
283                         continue;
284 
285                 if (s->size - size >= sizeof(void *))
286                         continue;
287 
288                 if (IS_ENABLED(CONFIG_SLAB) && align &&
289                         (align > s->align || s->align % align))
290                         continue;
291 
292                 return s;
293         }
294         return NULL;
295 }
296 
297 /*
298  * Figure out what the alignment of the objects will be given a set of
299  * flags, a user specified alignment and the size of the objects.
300  */
301 unsigned long calculate_alignment(unsigned long flags,
302                 unsigned long align, unsigned long size)
303 {
304         /*
305          * If the user wants hardware cache aligned objects then follow that
306          * suggestion if the object is sufficiently large.
307          *
308          * The hardware cache alignment cannot override the specified
309          * alignment though. If that is greater then use it.
310          */
311         if (flags & SLAB_HWCACHE_ALIGN) {
312                 unsigned long ralign = cache_line_size();
313                 while (size <= ralign / 2)
314                         ralign /= 2;
315                 align = max(align, ralign);
316         }
317 
318         if (align < ARCH_SLAB_MINALIGN)
319                 align = ARCH_SLAB_MINALIGN;
320 
321         return ALIGN(align, sizeof(void *));
322 }
323 
324 static struct kmem_cache *create_cache(const char *name,
325                 size_t object_size, size_t size, size_t align,
326                 unsigned long flags, void (*ctor)(void *),
327                 struct mem_cgroup *memcg, struct kmem_cache *root_cache)
328 {
329         struct kmem_cache *s;
330         int err;
331 
332         err = -ENOMEM;
333         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
334         if (!s)
335                 goto out;
336 
337         s->name = name;
338         s->object_size = object_size;
339         s->size = size;
340         s->align = align;
341         s->ctor = ctor;
342 
343         err = init_memcg_params(s, memcg, root_cache);
344         if (err)
345                 goto out_free_cache;
346 
347         err = __kmem_cache_create(s, flags);
348         if (err)
349                 goto out_free_cache;
350 
351         s->refcount = 1;
352         list_add(&s->list, &slab_caches);
353 out:
354         if (err)
355                 return ERR_PTR(err);
356         return s;
357 
358 out_free_cache:
359         destroy_memcg_params(s);
360         kmem_cache_free(kmem_cache, s);
361         goto out;
362 }
363 
364 /*
365  * kmem_cache_create - Create a cache.
366  * @name: A string which is used in /proc/slabinfo to identify this cache.
367  * @size: The size of objects to be created in this cache.
368  * @align: The required alignment for the objects.
369  * @flags: SLAB flags
370  * @ctor: A constructor for the objects.
371  *
372  * Returns a ptr to the cache on success, NULL on failure.
373  * Cannot be called within a interrupt, but can be interrupted.
374  * The @ctor is run when new pages are allocated by the cache.
375  *
376  * The flags are
377  *
378  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
379  * to catch references to uninitialised memory.
380  *
381  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
382  * for buffer overruns.
383  *
384  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
385  * cacheline.  This can be beneficial if you're counting cycles as closely
386  * as davem.
387  */
388 struct kmem_cache *
389 kmem_cache_create(const char *name, size_t size, size_t align,
390                   unsigned long flags, void (*ctor)(void *))
391 {
392         struct kmem_cache *s = NULL;
393         const char *cache_name;
394         int err;
395 
396         get_online_cpus();
397         get_online_mems();
398         memcg_get_cache_ids();
399 
400         mutex_lock(&slab_mutex);
401 
402         err = kmem_cache_sanity_check(name, size);
403         if (err) {
404                 goto out_unlock;
405         }
406 
407         /* Refuse requests with allocator specific flags */
408         if (flags & ~SLAB_FLAGS_PERMITTED) {
409                 err = -EINVAL;
410                 goto out_unlock;
411         }
412 
413         /*
414          * Some allocators will constraint the set of valid flags to a subset
415          * of all flags. We expect them to define CACHE_CREATE_MASK in this
416          * case, and we'll just provide them with a sanitized version of the
417          * passed flags.
418          */
419         flags &= CACHE_CREATE_MASK;
420 
421         s = __kmem_cache_alias(name, size, align, flags, ctor);
422         if (s)
423                 goto out_unlock;
424 
425         cache_name = kstrdup_const(name, GFP_KERNEL);
426         if (!cache_name) {
427                 err = -ENOMEM;
428                 goto out_unlock;
429         }
430 
431         s = create_cache(cache_name, size, size,
432                          calculate_alignment(flags, align, size),
433                          flags, ctor, NULL, NULL);
434         if (IS_ERR(s)) {
435                 err = PTR_ERR(s);
436                 kfree_const(cache_name);
437         }
438 
439 out_unlock:
440         mutex_unlock(&slab_mutex);
441 
442         memcg_put_cache_ids();
443         put_online_mems();
444         put_online_cpus();
445 
446         if (err) {
447                 if (flags & SLAB_PANIC)
448                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
449                                 name, err);
450                 else {
451                         pr_warn("kmem_cache_create(%s) failed with error %d\n",
452                                 name, err);
453                         dump_stack();
454                 }
455                 return NULL;
456         }
457         return s;
458 }
459 EXPORT_SYMBOL(kmem_cache_create);
460 
461 static int shutdown_cache(struct kmem_cache *s,
462                 struct list_head *release, bool *need_rcu_barrier)
463 {
464         if (__kmem_cache_shutdown(s) != 0)
465                 return -EBUSY;
466 
467         if (s->flags & SLAB_DESTROY_BY_RCU)
468                 *need_rcu_barrier = true;
469 
470         list_move(&s->list, release);
471         return 0;
472 }
473 
474 static void release_caches(struct list_head *release, bool need_rcu_barrier)
475 {
476         struct kmem_cache *s, *s2;
477 
478         if (need_rcu_barrier)
479                 rcu_barrier();
480 
481         list_for_each_entry_safe(s, s2, release, list) {
482 #ifdef SLAB_SUPPORTS_SYSFS
483                 sysfs_slab_remove(s);
484 #else
485                 slab_kmem_cache_release(s);
486 #endif
487         }
488 }
489 
490 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
491 /*
492  * memcg_create_kmem_cache - Create a cache for a memory cgroup.
493  * @memcg: The memory cgroup the new cache is for.
494  * @root_cache: The parent of the new cache.
495  *
496  * This function attempts to create a kmem cache that will serve allocation
497  * requests going from @memcg to @root_cache. The new cache inherits properties
498  * from its parent.
499  */
500 void memcg_create_kmem_cache(struct mem_cgroup *memcg,
501                              struct kmem_cache *root_cache)
502 {
503         static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
504         struct cgroup_subsys_state *css = &memcg->css;
505         struct memcg_cache_array *arr;
506         struct kmem_cache *s = NULL;
507         char *cache_name;
508         int idx;
509 
510         get_online_cpus();
511         get_online_mems();
512 
513         mutex_lock(&slab_mutex);
514 
515         /*
516          * The memory cgroup could have been offlined while the cache
517          * creation work was pending.
518          */
519         if (memcg->kmem_state != KMEM_ONLINE)
520                 goto out_unlock;
521 
522         idx = memcg_cache_id(memcg);
523         arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
524                                         lockdep_is_held(&slab_mutex));
525 
526         /*
527          * Since per-memcg caches are created asynchronously on first
528          * allocation (see memcg_kmem_get_cache()), several threads can try to
529          * create the same cache, but only one of them may succeed.
530          */
531         if (arr->entries[idx])
532                 goto out_unlock;
533 
534         cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
535         cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
536                                css->serial_nr, memcg_name_buf);
537         if (!cache_name)
538                 goto out_unlock;
539 
540         s = create_cache(cache_name, root_cache->object_size,
541                          root_cache->size, root_cache->align,
542                          root_cache->flags & CACHE_CREATE_MASK,
543                          root_cache->ctor, memcg, root_cache);
544         /*
545          * If we could not create a memcg cache, do not complain, because
546          * that's not critical at all as we can always proceed with the root
547          * cache.
548          */
549         if (IS_ERR(s)) {
550                 kfree(cache_name);
551                 goto out_unlock;
552         }
553 
554         list_add(&s->memcg_params.list, &root_cache->memcg_params.list);
555 
556         /*
557          * Since readers won't lock (see cache_from_memcg_idx()), we need a
558          * barrier here to ensure nobody will see the kmem_cache partially
559          * initialized.
560          */
561         smp_wmb();
562         arr->entries[idx] = s;
563 
564 out_unlock:
565         mutex_unlock(&slab_mutex);
566 
567         put_online_mems();
568         put_online_cpus();
569 }
570 
571 void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
572 {
573         int idx;
574         struct memcg_cache_array *arr;
575         struct kmem_cache *s, *c;
576 
577         idx = memcg_cache_id(memcg);
578 
579         get_online_cpus();
580         get_online_mems();
581 
582 #ifdef CONFIG_SLUB
583         /*
584          * In case of SLUB, we need to disable empty slab caching to
585          * avoid pinning the offline memory cgroup by freeable kmem
586          * pages charged to it. SLAB doesn't need this, as it
587          * periodically purges unused slabs.
588          */
589         mutex_lock(&slab_mutex);
590         list_for_each_entry(s, &slab_caches, list) {
591                 c = is_root_cache(s) ? cache_from_memcg_idx(s, idx) : NULL;
592                 if (c) {
593                         c->cpu_partial = 0;
594                         c->min_partial = 0;
595                 }
596         }
597         mutex_unlock(&slab_mutex);
598         /*
599          * kmem_cache->cpu_partial is checked locklessly (see
600          * put_cpu_partial()). Make sure the change is visible.
601          */
602         synchronize_sched();
603 #endif
604 
605         mutex_lock(&slab_mutex);
606         list_for_each_entry(s, &slab_caches, list) {
607                 if (!is_root_cache(s))
608                         continue;
609 
610                 arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
611                                                 lockdep_is_held(&slab_mutex));
612                 c = arr->entries[idx];
613                 if (!c)
614                         continue;
615 
616                 __kmem_cache_shrink(c);
617                 arr->entries[idx] = NULL;
618         }
619         mutex_unlock(&slab_mutex);
620 
621         put_online_mems();
622         put_online_cpus();
623 }
624 
625 static int __shutdown_memcg_cache(struct kmem_cache *s,
626                 struct list_head *release, bool *need_rcu_barrier)
627 {
628         BUG_ON(is_root_cache(s));
629 
630         if (shutdown_cache(s, release, need_rcu_barrier))
631                 return -EBUSY;
632 
633         list_del(&s->memcg_params.list);
634         return 0;
635 }
636 
637 void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
638 {
639         LIST_HEAD(release);
640         bool need_rcu_barrier = false;
641         struct kmem_cache *s, *s2;
642 
643         get_online_cpus();
644         get_online_mems();
645 
646         mutex_lock(&slab_mutex);
647         list_for_each_entry_safe(s, s2, &slab_caches, list) {
648                 if (is_root_cache(s) || s->memcg_params.memcg != memcg)
649                         continue;
650                 /*
651                  * The cgroup is about to be freed and therefore has no charges
652                  * left. Hence, all its caches must be empty by now.
653                  */
654                 BUG_ON(__shutdown_memcg_cache(s, &release, &need_rcu_barrier));
655         }
656         mutex_unlock(&slab_mutex);
657 
658         put_online_mems();
659         put_online_cpus();
660 
661         release_caches(&release, need_rcu_barrier);
662 }
663 
664 static int shutdown_memcg_caches(struct kmem_cache *s,
665                 struct list_head *release, bool *need_rcu_barrier)
666 {
667         struct memcg_cache_array *arr;
668         struct kmem_cache *c, *c2;
669         LIST_HEAD(busy);
670         int i;
671 
672         BUG_ON(!is_root_cache(s));
673 
674         /*
675          * First, shutdown active caches, i.e. caches that belong to online
676          * memory cgroups.
677          */
678         arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
679                                         lockdep_is_held(&slab_mutex));
680         for_each_memcg_cache_index(i) {
681                 c = arr->entries[i];
682                 if (!c)
683                         continue;
684                 if (__shutdown_memcg_cache(c, release, need_rcu_barrier))
685                         /*
686                          * The cache still has objects. Move it to a temporary
687                          * list so as not to try to destroy it for a second
688                          * time while iterating over inactive caches below.
689                          */
690                         list_move(&c->memcg_params.list, &busy);
691                 else
692                         /*
693                          * The cache is empty and will be destroyed soon. Clear
694                          * the pointer to it in the memcg_caches array so that
695                          * it will never be accessed even if the root cache
696                          * stays alive.
697                          */
698                         arr->entries[i] = NULL;
699         }
700 
701         /*
702          * Second, shutdown all caches left from memory cgroups that are now
703          * offline.
704          */
705         list_for_each_entry_safe(c, c2, &s->memcg_params.list,
706                                  memcg_params.list)
707                 __shutdown_memcg_cache(c, release, need_rcu_barrier);
708 
709         list_splice(&busy, &s->memcg_params.list);
710 
711         /*
712          * A cache being destroyed must be empty. In particular, this means
713          * that all per memcg caches attached to it must be empty too.
714          */
715         if (!list_empty(&s->memcg_params.list))
716                 return -EBUSY;
717         return 0;
718 }
719 #else
720 static inline int shutdown_memcg_caches(struct kmem_cache *s,
721                 struct list_head *release, bool *need_rcu_barrier)
722 {
723         return 0;
724 }
725 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */
726 
727 void slab_kmem_cache_release(struct kmem_cache *s)
728 {
729         __kmem_cache_release(s);
730         destroy_memcg_params(s);
731         kfree_const(s->name);
732         kmem_cache_free(kmem_cache, s);
733 }
734 
735 void kmem_cache_destroy(struct kmem_cache *s)
736 {
737         LIST_HEAD(release);
738         bool need_rcu_barrier = false;
739         int err;
740 
741         if (unlikely(!s))
742                 return;
743 
744         get_online_cpus();
745         get_online_mems();
746 
747         kasan_cache_destroy(s);
748         mutex_lock(&slab_mutex);
749 
750         s->refcount--;
751         if (s->refcount)
752                 goto out_unlock;
753 
754         err = shutdown_memcg_caches(s, &release, &need_rcu_barrier);
755         if (!err)
756                 err = shutdown_cache(s, &release, &need_rcu_barrier);
757 
758         if (err) {
759                 pr_err("kmem_cache_destroy %s: Slab cache still has objects\n",
760                        s->name);
761                 dump_stack();
762         }
763 out_unlock:
764         mutex_unlock(&slab_mutex);
765 
766         put_online_mems();
767         put_online_cpus();
768 
769         release_caches(&release, need_rcu_barrier);
770 }
771 EXPORT_SYMBOL(kmem_cache_destroy);
772 
773 /**
774  * kmem_cache_shrink - Shrink a cache.
775  * @cachep: The cache to shrink.
776  *
777  * Releases as many slabs as possible for a cache.
778  * To help debugging, a zero exit status indicates all slabs were released.
779  */
780 int kmem_cache_shrink(struct kmem_cache *cachep)
781 {
782         int ret;
783 
784         get_online_cpus();
785         get_online_mems();
786         kasan_cache_shrink(cachep);
787         ret = __kmem_cache_shrink(cachep);
788         put_online_mems();
789         put_online_cpus();
790         return ret;
791 }
792 EXPORT_SYMBOL(kmem_cache_shrink);
793 
794 bool slab_is_available(void)
795 {
796         return slab_state >= UP;
797 }
798 
799 #ifndef CONFIG_SLOB
800 /* Create a cache during boot when no slab services are available yet */
801 void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
802                 unsigned long flags)
803 {
804         int err;
805 
806         s->name = name;
807         s->size = s->object_size = size;
808         s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
809 
810         slab_init_memcg_params(s);
811 
812         err = __kmem_cache_create(s, flags);
813 
814         if (err)
815                 panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
816                                         name, size, err);
817 
818         s->refcount = -1;       /* Exempt from merging for now */
819 }
820 
821 struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
822                                 unsigned long flags)
823 {
824         struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
825 
826         if (!s)
827                 panic("Out of memory when creating slab %s\n", name);
828 
829         create_boot_cache(s, name, size, flags);
830         list_add(&s->list, &slab_caches);
831         s->refcount = 1;
832         return s;
833 }
834 
835 struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
836 EXPORT_SYMBOL(kmalloc_caches);
837 
838 #ifdef CONFIG_ZONE_DMA
839 struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
840 EXPORT_SYMBOL(kmalloc_dma_caches);
841 #endif
842 
843 /*
844  * Conversion table for small slabs sizes / 8 to the index in the
845  * kmalloc array. This is necessary for slabs < 192 since we have non power
846  * of two cache sizes there. The size of larger slabs can be determined using
847  * fls.
848  */
849 static s8 size_index[24] = {
850         3,      /* 8 */
851         4,      /* 16 */
852         5,      /* 24 */
853         5,      /* 32 */
854         6,      /* 40 */
855         6,      /* 48 */
856         6,      /* 56 */
857         6,      /* 64 */
858         1,      /* 72 */
859         1,      /* 80 */
860         1,      /* 88 */
861         1,      /* 96 */
862         7,      /* 104 */
863         7,      /* 112 */
864         7,      /* 120 */
865         7,      /* 128 */
866         2,      /* 136 */
867         2,      /* 144 */
868         2,      /* 152 */
869         2,      /* 160 */
870         2,      /* 168 */
871         2,      /* 176 */
872         2,      /* 184 */
873         2       /* 192 */
874 };
875 
876 static inline int size_index_elem(size_t bytes)
877 {
878         return (bytes - 1) / 8;
879 }
880 
881 /*
882  * Find the kmem_cache structure that serves a given size of
883  * allocation
884  */
885 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
886 {
887         int index;
888 
889         if (unlikely(size > KMALLOC_MAX_SIZE)) {
890                 WARN_ON_ONCE(!(flags & __GFP_NOWARN));
891                 return NULL;
892         }
893 
894         if (size <= 192) {
895                 if (!size)
896                         return ZERO_SIZE_PTR;
897 
898                 index = size_index[size_index_elem(size)];
899         } else
900                 index = fls(size - 1);
901 
902 #ifdef CONFIG_ZONE_DMA
903         if (unlikely((flags & GFP_DMA)))
904                 return kmalloc_dma_caches[index];
905 
906 #endif
907         return kmalloc_caches[index];
908 }
909 
910 /*
911  * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
912  * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
913  * kmalloc-67108864.
914  */
915 static struct {
916         const char *name;
917         unsigned long size;
918 } const kmalloc_info[] __initconst = {
919         {NULL,                      0},         {"kmalloc-96",             96},
920         {"kmalloc-192",           192},         {"kmalloc-8",               8},
921         {"kmalloc-16",             16},         {"kmalloc-32",             32},
922         {"kmalloc-64",             64},         {"kmalloc-128",           128},
923         {"kmalloc-256",           256},         {"kmalloc-512",           512},
924         {"kmalloc-1024",         1024},         {"kmalloc-2048",         2048},
925         {"kmalloc-4096",         4096},         {"kmalloc-8192",         8192},
926         {"kmalloc-16384",       16384},         {"kmalloc-32768",       32768},
927         {"kmalloc-65536",       65536},         {"kmalloc-131072",     131072},
928         {"kmalloc-262144",     262144},         {"kmalloc-524288",     524288},
929         {"kmalloc-1048576",   1048576},         {"kmalloc-2097152",   2097152},
930         {"kmalloc-4194304",   4194304},         {"kmalloc-8388608",   8388608},
931         {"kmalloc-16777216", 16777216},         {"kmalloc-33554432", 33554432},
932         {"kmalloc-67108864", 67108864}
933 };
934 
935 /*
936  * Patch up the size_index table if we have strange large alignment
937  * requirements for the kmalloc array. This is only the case for
938  * MIPS it seems. The standard arches will not generate any code here.
939  *
940  * Largest permitted alignment is 256 bytes due to the way we
941  * handle the index determination for the smaller caches.
942  *
943  * Make sure that nothing crazy happens if someone starts tinkering
944  * around with ARCH_KMALLOC_MINALIGN
945  */
946 void __init setup_kmalloc_cache_index_table(void)
947 {
948         int i;
949 
950         BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
951                 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
952 
953         for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
954                 int elem = size_index_elem(i);
955 
956                 if (elem >= ARRAY_SIZE(size_index))
957                         break;
958                 size_index[elem] = KMALLOC_SHIFT_LOW;
959         }
960 
961         if (KMALLOC_MIN_SIZE >= 64) {
962                 /*
963                  * The 96 byte size cache is not used if the alignment
964                  * is 64 byte.
965                  */
966                 for (i = 64 + 8; i <= 96; i += 8)
967                         size_index[size_index_elem(i)] = 7;
968 
969         }
970 
971         if (KMALLOC_MIN_SIZE >= 128) {
972                 /*
973                  * The 192 byte sized cache is not used if the alignment
974                  * is 128 byte. Redirect kmalloc to use the 256 byte cache
975                  * instead.
976                  */
977                 for (i = 128 + 8; i <= 192; i += 8)
978                         size_index[size_index_elem(i)] = 8;
979         }
980 }
981 
982 static void __init new_kmalloc_cache(int idx, unsigned long flags)
983 {
984         kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
985                                         kmalloc_info[idx].size, flags);
986 }
987 
988 /*
989  * Create the kmalloc array. Some of the regular kmalloc arrays
990  * may already have been created because they were needed to
991  * enable allocations for slab creation.
992  */
993 void __init create_kmalloc_caches(unsigned long flags)
994 {
995         int i;
996 
997         for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
998                 if (!kmalloc_caches[i])
999                         new_kmalloc_cache(i, flags);
1000 
1001                 /*
1002                  * Caches that are not of the two-to-the-power-of size.
1003                  * These have to be created immediately after the
1004                  * earlier power of two caches
1005                  */
1006                 if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
1007                         new_kmalloc_cache(1, flags);
1008                 if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
1009                         new_kmalloc_cache(2, flags);
1010         }
1011 
1012         /* Kmalloc array is now usable */
1013         slab_state = UP;
1014 
1015 #ifdef CONFIG_ZONE_DMA
1016         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
1017                 struct kmem_cache *s = kmalloc_caches[i];
1018 
1019                 if (s) {
1020                         int size = kmalloc_size(i);
1021                         char *n = kasprintf(GFP_NOWAIT,
1022                                  "dma-kmalloc-%d", size);
1023 
1024                         BUG_ON(!n);
1025                         kmalloc_dma_caches[i] = create_kmalloc_cache(n,
1026                                 size, SLAB_CACHE_DMA | flags);
1027                 }
1028         }
1029 #endif
1030 }
1031 #endif /* !CONFIG_SLOB */
1032 
1033 /*
1034  * To avoid unnecessary overhead, we pass through large allocation requests
1035  * directly to the page allocator. We use __GFP_COMP, because we will need to
1036  * know the allocation order to free the pages properly in kfree.
1037  */
1038 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
1039 {
1040         void *ret;
1041         struct page *page;
1042 
1043         flags |= __GFP_COMP;
1044         page = alloc_pages(flags, order);
1045         ret = page ? page_address(page) : NULL;
1046         kmemleak_alloc(ret, size, 1, flags);
1047         kasan_kmalloc_large(ret, size, flags);
1048         return ret;
1049 }
1050 EXPORT_SYMBOL(kmalloc_order);
1051 
1052 #ifdef CONFIG_TRACING
1053 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
1054 {
1055         void *ret = kmalloc_order(size, flags, order);
1056         trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
1057         return ret;
1058 }
1059 EXPORT_SYMBOL(kmalloc_order_trace);
1060 #endif
1061 
1062 #ifdef CONFIG_SLAB_FREELIST_RANDOM
1063 /* Randomize a generic freelist */
1064 static void freelist_randomize(struct rnd_state *state, unsigned int *list,
1065                         size_t count)
1066 {
1067         size_t i;
1068         unsigned int rand;
1069 
1070         for (i = 0; i < count; i++)
1071                 list[i] = i;
1072 
1073         /* Fisher-Yates shuffle */
1074         for (i = count - 1; i > 0; i--) {
1075                 rand = prandom_u32_state(state);
1076                 rand %= (i + 1);
1077                 swap(list[i], list[rand]);
1078         }
1079 }
1080 
1081 /* Create a random sequence per cache */
1082 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
1083                                     gfp_t gfp)
1084 {
1085         struct rnd_state state;
1086 
1087         if (count < 2 || cachep->random_seq)
1088                 return 0;
1089 
1090         cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
1091         if (!cachep->random_seq)
1092                 return -ENOMEM;
1093 
1094         /* Get best entropy at this stage of boot */
1095         prandom_seed_state(&state, get_random_long());
1096 
1097         freelist_randomize(&state, cachep->random_seq, count);
1098         return 0;
1099 }
1100 
1101 /* Destroy the per-cache random freelist sequence */
1102 void cache_random_seq_destroy(struct kmem_cache *cachep)
1103 {
1104         kfree(cachep->random_seq);
1105         cachep->random_seq = NULL;
1106 }
1107 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1108 
1109 #ifdef CONFIG_SLABINFO
1110 
1111 #ifdef CONFIG_SLAB
1112 #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
1113 #else
1114 #define SLABINFO_RIGHTS S_IRUSR
1115 #endif
1116 
1117 static void print_slabinfo_header(struct seq_file *m)
1118 {
1119         /*
1120          * Output format version, so at least we can change it
1121          * without _too_ many complaints.
1122          */
1123 #ifdef CONFIG_DEBUG_SLAB
1124         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
1125 #else
1126         seq_puts(m, "slabinfo - version: 2.1\n");
1127 #endif
1128         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1129         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1130         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1131 #ifdef CONFIG_DEBUG_SLAB
1132         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
1133         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
1134 #endif
1135         seq_putc(m, '\n');
1136 }
1137 
1138 void *slab_start(struct seq_file *m, loff_t *pos)
1139 {
1140         mutex_lock(&slab_mutex);
1141         return seq_list_start(&slab_caches, *pos);
1142 }
1143 
1144 void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1145 {
1146         return seq_list_next(p, &slab_caches, pos);
1147 }
1148 
1149 void slab_stop(struct seq_file *m, void *p)
1150 {
1151         mutex_unlock(&slab_mutex);
1152 }
1153 
1154 static void
1155 memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
1156 {
1157         struct kmem_cache *c;
1158         struct slabinfo sinfo;
1159 
1160         if (!is_root_cache(s))
1161                 return;
1162 
1163         for_each_memcg_cache(c, s) {
1164                 memset(&sinfo, 0, sizeof(sinfo));
1165                 get_slabinfo(c, &sinfo);
1166 
1167                 info->active_slabs += sinfo.active_slabs;
1168                 info->num_slabs += sinfo.num_slabs;
1169                 info->shared_avail += sinfo.shared_avail;
1170                 info->active_objs += sinfo.active_objs;
1171                 info->num_objs += sinfo.num_objs;
1172         }
1173 }
1174 
1175 static void cache_show(struct kmem_cache *s, struct seq_file *m)
1176 {
1177         struct slabinfo sinfo;
1178 
1179         memset(&sinfo, 0, sizeof(sinfo));
1180         get_slabinfo(s, &sinfo);
1181 
1182         memcg_accumulate_slabinfo(s, &sinfo);
1183 
1184         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1185                    cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
1186                    sinfo.objects_per_slab, (1 << sinfo.cache_order));
1187 
1188         seq_printf(m, " : tunables %4u %4u %4u",
1189                    sinfo.limit, sinfo.batchcount, sinfo.shared);
1190         seq_printf(m, " : slabdata %6lu %6lu %6lu",
1191                    sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1192         slabinfo_show_stats(m, s);
1193         seq_putc(m, '\n');
1194 }
1195 
1196 static int slab_show(struct seq_file *m, void *p)
1197 {
1198         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1199 
1200         if (p == slab_caches.next)
1201                 print_slabinfo_header(m);
1202         if (is_root_cache(s))
1203                 cache_show(s, m);
1204         return 0;
1205 }
1206 
1207 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
1208 int memcg_slab_show(struct seq_file *m, void *p)
1209 {
1210         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1211         struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
1212 
1213         if (p == slab_caches.next)
1214                 print_slabinfo_header(m);
1215         if (!is_root_cache(s) && s->memcg_params.memcg == memcg)
1216                 cache_show(s, m);
1217         return 0;
1218 }
1219 #endif
1220 
1221 /*
1222  * slabinfo_op - iterator that generates /proc/slabinfo
1223  *
1224  * Output layout:
1225  * cache-name
1226  * num-active-objs
1227  * total-objs
1228  * object size
1229  * num-active-slabs
1230  * total-slabs
1231  * num-pages-per-slab
1232  * + further values on SMP and with statistics enabled
1233  */
1234 static const struct seq_operations slabinfo_op = {
1235         .start = slab_start,
1236         .next = slab_next,
1237         .stop = slab_stop,
1238         .show = slab_show,
1239 };
1240 
1241 static int slabinfo_open(struct inode *inode, struct file *file)
1242 {
1243         return seq_open(file, &slabinfo_op);
1244 }
1245 
1246 static const struct file_operations proc_slabinfo_operations = {
1247         .open           = slabinfo_open,
1248         .read           = seq_read,
1249         .write          = slabinfo_write,
1250         .llseek         = seq_lseek,
1251         .release        = seq_release,
1252 };
1253 
1254 static int __init slab_proc_init(void)
1255 {
1256         proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
1257                                                 &proc_slabinfo_operations);
1258         return 0;
1259 }
1260 module_init(slab_proc_init);
1261 #endif /* CONFIG_SLABINFO */
1262 
1263 static __always_inline void *__do_krealloc(const void *p, size_t new_size,
1264                                            gfp_t flags)
1265 {
1266         void *ret;
1267         size_t ks = 0;
1268 
1269         if (p)
1270                 ks = ksize(p);
1271 
1272         if (ks >= new_size) {
1273                 kasan_krealloc((void *)p, new_size, flags);
1274                 return (void *)p;
1275         }
1276 
1277         ret = kmalloc_track_caller(new_size, flags);
1278         if (ret && p)
1279                 memcpy(ret, p, ks);
1280 
1281         return ret;
1282 }
1283 
1284 /**
1285  * __krealloc - like krealloc() but don't free @p.
1286  * @p: object to reallocate memory for.
1287  * @new_size: how many bytes of memory are required.
1288  * @flags: the type of memory to allocate.
1289  *
1290  * This function is like krealloc() except it never frees the originally
1291  * allocated buffer. Use this if you don't want to free the buffer immediately
1292  * like, for example, with RCU.
1293  */
1294 void *__krealloc(const void *p, size_t new_size, gfp_t flags)
1295 {
1296         if (unlikely(!new_size))
1297                 return ZERO_SIZE_PTR;
1298 
1299         return __do_krealloc(p, new_size, flags);
1300 
1301 }
1302 EXPORT_SYMBOL(__krealloc);
1303 
1304 /**
1305  * krealloc - reallocate memory. The contents will remain unchanged.
1306  * @p: object to reallocate memory for.
1307  * @new_size: how many bytes of memory are required.
1308  * @flags: the type of memory to allocate.
1309  *
1310  * The contents of the object pointed to are preserved up to the
1311  * lesser of the new and old sizes.  If @p is %NULL, krealloc()
1312  * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
1313  * %NULL pointer, the object pointed to is freed.
1314  */
1315 void *krealloc(const void *p, size_t new_size, gfp_t flags)
1316 {
1317         void *ret;
1318 
1319         if (unlikely(!new_size)) {
1320                 kfree(p);
1321                 return ZERO_SIZE_PTR;
1322         }
1323 
1324         ret = __do_krealloc(p, new_size, flags);
1325         if (ret && p != ret)
1326                 kfree(p);
1327 
1328         return ret;
1329 }
1330 EXPORT_SYMBOL(krealloc);
1331 
1332 /**
1333  * kzfree - like kfree but zero memory
1334  * @p: object to free memory of
1335  *
1336  * The memory of the object @p points to is zeroed before freed.
1337  * If @p is %NULL, kzfree() does nothing.
1338  *
1339  * Note: this function zeroes the whole allocated buffer which can be a good
1340  * deal bigger than the requested buffer size passed to kmalloc(). So be
1341  * careful when using this function in performance sensitive code.
1342  */
1343 void kzfree(const void *p)
1344 {
1345         size_t ks;
1346         void *mem = (void *)p;
1347 
1348         if (unlikely(ZERO_OR_NULL_PTR(mem)))
1349                 return;
1350         ks = ksize(mem);
1351         memset(mem, 0, ks);
1352         kfree(mem);
1353 }
1354 EXPORT_SYMBOL(kzfree);
1355 
1356 /* Tracepoints definitions. */
1357 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1358 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1359 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
1360 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
1361 EXPORT_TRACEPOINT_SYMBOL(kfree);
1362 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1363 

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