xref: /openbmc/linux/mm/slab_common.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
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