xref: /openbmc/linux/mm/slab_common.c (revision faffb083)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Slab allocator functions that are independent of the allocator strategy
4  *
5  * (C) 2012 Christoph Lameter <cl@linux.com>
6  */
7 #include <linux/slab.h>
8 
9 #include <linux/mm.h>
10 #include <linux/poison.h>
11 #include <linux/interrupt.h>
12 #include <linux/memory.h>
13 #include <linux/cache.h>
14 #include <linux/compiler.h>
15 #include <linux/kfence.h>
16 #include <linux/module.h>
17 #include <linux/cpu.h>
18 #include <linux/uaccess.h>
19 #include <linux/seq_file.h>
20 #include <linux/proc_fs.h>
21 #include <linux/debugfs.h>
22 #include <linux/kasan.h>
23 #include <asm/cacheflush.h>
24 #include <asm/tlbflush.h>
25 #include <asm/page.h>
26 #include <linux/memcontrol.h>
27 #include <linux/stackdepot.h>
28 
29 #include "internal.h"
30 #include "slab.h"
31 
32 #define CREATE_TRACE_POINTS
33 #include <trace/events/kmem.h>
34 
35 enum slab_state slab_state;
36 LIST_HEAD(slab_caches);
37 DEFINE_MUTEX(slab_mutex);
38 struct kmem_cache *kmem_cache;
39 
40 static LIST_HEAD(slab_caches_to_rcu_destroy);
41 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work);
42 static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
43 		    slab_caches_to_rcu_destroy_workfn);
44 
45 /*
46  * Set of flags that will prevent slab merging
47  */
48 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
49 		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
50 		SLAB_FAILSLAB | kasan_never_merge())
51 
52 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
53 			 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
54 
55 /*
56  * Merge control. If this is set then no merging of slab caches will occur.
57  */
58 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
59 
60 static int __init setup_slab_nomerge(char *str)
61 {
62 	slab_nomerge = true;
63 	return 1;
64 }
65 
66 static int __init setup_slab_merge(char *str)
67 {
68 	slab_nomerge = false;
69 	return 1;
70 }
71 
72 #ifdef CONFIG_SLUB
73 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
74 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0);
75 #endif
76 
77 __setup("slab_nomerge", setup_slab_nomerge);
78 __setup("slab_merge", setup_slab_merge);
79 
80 /*
81  * Determine the size of a slab object
82  */
83 unsigned int kmem_cache_size(struct kmem_cache *s)
84 {
85 	return s->object_size;
86 }
87 EXPORT_SYMBOL(kmem_cache_size);
88 
89 #ifdef CONFIG_DEBUG_VM
90 static int kmem_cache_sanity_check(const char *name, unsigned int size)
91 {
92 	if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
93 		pr_err("kmem_cache_create(%s) integrity check failed\n", name);
94 		return -EINVAL;
95 	}
96 
97 	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
98 	return 0;
99 }
100 #else
101 static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
102 {
103 	return 0;
104 }
105 #endif
106 
107 /*
108  * Figure out what the alignment of the objects will be given a set of
109  * flags, a user specified alignment and the size of the objects.
110  */
111 static unsigned int calculate_alignment(slab_flags_t flags,
112 		unsigned int align, unsigned int size)
113 {
114 	/*
115 	 * If the user wants hardware cache aligned objects then follow that
116 	 * suggestion if the object is sufficiently large.
117 	 *
118 	 * The hardware cache alignment cannot override the specified
119 	 * alignment though. If that is greater then use it.
120 	 */
121 	if (flags & SLAB_HWCACHE_ALIGN) {
122 		unsigned int ralign;
123 
124 		ralign = cache_line_size();
125 		while (size <= ralign / 2)
126 			ralign /= 2;
127 		align = max(align, ralign);
128 	}
129 
130 	align = max(align, arch_slab_minalign());
131 
132 	return ALIGN(align, sizeof(void *));
133 }
134 
135 /*
136  * Find a mergeable slab cache
137  */
138 int slab_unmergeable(struct kmem_cache *s)
139 {
140 	if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
141 		return 1;
142 
143 	if (s->ctor)
144 		return 1;
145 
146 #ifdef CONFIG_HARDENED_USERCOPY
147 	if (s->usersize)
148 		return 1;
149 #endif
150 
151 	/*
152 	 * We may have set a slab to be unmergeable during bootstrap.
153 	 */
154 	if (s->refcount < 0)
155 		return 1;
156 
157 	return 0;
158 }
159 
160 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
161 		slab_flags_t flags, const char *name, void (*ctor)(void *))
162 {
163 	struct kmem_cache *s;
164 
165 	if (slab_nomerge)
166 		return NULL;
167 
168 	if (ctor)
169 		return NULL;
170 
171 	size = ALIGN(size, sizeof(void *));
172 	align = calculate_alignment(flags, align, size);
173 	size = ALIGN(size, align);
174 	flags = kmem_cache_flags(size, flags, name);
175 
176 	if (flags & SLAB_NEVER_MERGE)
177 		return NULL;
178 
179 	list_for_each_entry_reverse(s, &slab_caches, list) {
180 		if (slab_unmergeable(s))
181 			continue;
182 
183 		if (size > s->size)
184 			continue;
185 
186 		if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
187 			continue;
188 		/*
189 		 * Check if alignment is compatible.
190 		 * Courtesy of Adrian Drzewiecki
191 		 */
192 		if ((s->size & ~(align - 1)) != s->size)
193 			continue;
194 
195 		if (s->size - size >= sizeof(void *))
196 			continue;
197 
198 		if (IS_ENABLED(CONFIG_SLAB) && align &&
199 			(align > s->align || s->align % align))
200 			continue;
201 
202 		return s;
203 	}
204 	return NULL;
205 }
206 
207 static struct kmem_cache *create_cache(const char *name,
208 		unsigned int object_size, unsigned int align,
209 		slab_flags_t flags, unsigned int useroffset,
210 		unsigned int usersize, void (*ctor)(void *),
211 		struct kmem_cache *root_cache)
212 {
213 	struct kmem_cache *s;
214 	int err;
215 
216 	if (WARN_ON(useroffset + usersize > object_size))
217 		useroffset = usersize = 0;
218 
219 	err = -ENOMEM;
220 	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
221 	if (!s)
222 		goto out;
223 
224 	s->name = name;
225 	s->size = s->object_size = object_size;
226 	s->align = align;
227 	s->ctor = ctor;
228 #ifdef CONFIG_HARDENED_USERCOPY
229 	s->useroffset = useroffset;
230 	s->usersize = usersize;
231 #endif
232 
233 	err = __kmem_cache_create(s, flags);
234 	if (err)
235 		goto out_free_cache;
236 
237 	s->refcount = 1;
238 	list_add(&s->list, &slab_caches);
239 out:
240 	if (err)
241 		return ERR_PTR(err);
242 	return s;
243 
244 out_free_cache:
245 	kmem_cache_free(kmem_cache, s);
246 	goto out;
247 }
248 
249 /**
250  * kmem_cache_create_usercopy - Create a cache with a region suitable
251  * for copying to userspace
252  * @name: A string which is used in /proc/slabinfo to identify this cache.
253  * @size: The size of objects to be created in this cache.
254  * @align: The required alignment for the objects.
255  * @flags: SLAB flags
256  * @useroffset: Usercopy region offset
257  * @usersize: Usercopy region size
258  * @ctor: A constructor for the objects.
259  *
260  * Cannot be called within a interrupt, but can be interrupted.
261  * The @ctor is run when new pages are allocated by the cache.
262  *
263  * The flags are
264  *
265  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
266  * to catch references to uninitialised memory.
267  *
268  * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check
269  * for buffer overruns.
270  *
271  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
272  * cacheline.  This can be beneficial if you're counting cycles as closely
273  * as davem.
274  *
275  * Return: a pointer to the cache on success, NULL on failure.
276  */
277 struct kmem_cache *
278 kmem_cache_create_usercopy(const char *name,
279 		  unsigned int size, unsigned int align,
280 		  slab_flags_t flags,
281 		  unsigned int useroffset, unsigned int usersize,
282 		  void (*ctor)(void *))
283 {
284 	struct kmem_cache *s = NULL;
285 	const char *cache_name;
286 	int err;
287 
288 #ifdef CONFIG_SLUB_DEBUG
289 	/*
290 	 * If no slub_debug was enabled globally, the static key is not yet
291 	 * enabled by setup_slub_debug(). Enable it if the cache is being
292 	 * created with any of the debugging flags passed explicitly.
293 	 * It's also possible that this is the first cache created with
294 	 * SLAB_STORE_USER and we should init stack_depot for it.
295 	 */
296 	if (flags & SLAB_DEBUG_FLAGS)
297 		static_branch_enable(&slub_debug_enabled);
298 	if (flags & SLAB_STORE_USER)
299 		stack_depot_init();
300 #endif
301 
302 	mutex_lock(&slab_mutex);
303 
304 	err = kmem_cache_sanity_check(name, size);
305 	if (err) {
306 		goto out_unlock;
307 	}
308 
309 	/* Refuse requests with allocator specific flags */
310 	if (flags & ~SLAB_FLAGS_PERMITTED) {
311 		err = -EINVAL;
312 		goto out_unlock;
313 	}
314 
315 	/*
316 	 * Some allocators will constraint the set of valid flags to a subset
317 	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
318 	 * case, and we'll just provide them with a sanitized version of the
319 	 * passed flags.
320 	 */
321 	flags &= CACHE_CREATE_MASK;
322 
323 	/* Fail closed on bad usersize of useroffset values. */
324 	if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
325 	    WARN_ON(!usersize && useroffset) ||
326 	    WARN_ON(size < usersize || size - usersize < useroffset))
327 		usersize = useroffset = 0;
328 
329 	if (!usersize)
330 		s = __kmem_cache_alias(name, size, align, flags, ctor);
331 	if (s)
332 		goto out_unlock;
333 
334 	cache_name = kstrdup_const(name, GFP_KERNEL);
335 	if (!cache_name) {
336 		err = -ENOMEM;
337 		goto out_unlock;
338 	}
339 
340 	s = create_cache(cache_name, size,
341 			 calculate_alignment(flags, align, size),
342 			 flags, useroffset, usersize, ctor, NULL);
343 	if (IS_ERR(s)) {
344 		err = PTR_ERR(s);
345 		kfree_const(cache_name);
346 	}
347 
348 out_unlock:
349 	mutex_unlock(&slab_mutex);
350 
351 	if (err) {
352 		if (flags & SLAB_PANIC)
353 			panic("%s: Failed to create slab '%s'. Error %d\n",
354 				__func__, name, err);
355 		else {
356 			pr_warn("%s(%s) failed with error %d\n",
357 				__func__, name, err);
358 			dump_stack();
359 		}
360 		return NULL;
361 	}
362 	return s;
363 }
364 EXPORT_SYMBOL(kmem_cache_create_usercopy);
365 
366 /**
367  * kmem_cache_create - Create a cache.
368  * @name: A string which is used in /proc/slabinfo to identify this cache.
369  * @size: The size of objects to be created in this cache.
370  * @align: The required alignment for the objects.
371  * @flags: SLAB flags
372  * @ctor: A constructor for the objects.
373  *
374  * Cannot be called within a interrupt, but can be interrupted.
375  * The @ctor is run when new pages are allocated by the cache.
376  *
377  * The flags are
378  *
379  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
380  * to catch references to uninitialised memory.
381  *
382  * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check
383  * for buffer overruns.
384  *
385  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
386  * cacheline.  This can be beneficial if you're counting cycles as closely
387  * as davem.
388  *
389  * Return: a pointer to the cache on success, NULL on failure.
390  */
391 struct kmem_cache *
392 kmem_cache_create(const char *name, unsigned int size, unsigned int align,
393 		slab_flags_t flags, void (*ctor)(void *))
394 {
395 	return kmem_cache_create_usercopy(name, size, align, flags, 0, 0,
396 					  ctor);
397 }
398 EXPORT_SYMBOL(kmem_cache_create);
399 
400 #ifdef SLAB_SUPPORTS_SYSFS
401 /*
402  * For a given kmem_cache, kmem_cache_destroy() should only be called
403  * once or there will be a use-after-free problem. The actual deletion
404  * and release of the kobject does not need slab_mutex or cpu_hotplug_lock
405  * protection. So they are now done without holding those locks.
406  *
407  * Note that there will be a slight delay in the deletion of sysfs files
408  * if kmem_cache_release() is called indrectly from a work function.
409  */
410 static void kmem_cache_release(struct kmem_cache *s)
411 {
412 	sysfs_slab_unlink(s);
413 	sysfs_slab_release(s);
414 }
415 #else
416 static void kmem_cache_release(struct kmem_cache *s)
417 {
418 	slab_kmem_cache_release(s);
419 }
420 #endif
421 
422 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
423 {
424 	LIST_HEAD(to_destroy);
425 	struct kmem_cache *s, *s2;
426 
427 	/*
428 	 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the
429 	 * @slab_caches_to_rcu_destroy list.  The slab pages are freed
430 	 * through RCU and the associated kmem_cache are dereferenced
431 	 * while freeing the pages, so the kmem_caches should be freed only
432 	 * after the pending RCU operations are finished.  As rcu_barrier()
433 	 * is a pretty slow operation, we batch all pending destructions
434 	 * asynchronously.
435 	 */
436 	mutex_lock(&slab_mutex);
437 	list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy);
438 	mutex_unlock(&slab_mutex);
439 
440 	if (list_empty(&to_destroy))
441 		return;
442 
443 	rcu_barrier();
444 
445 	list_for_each_entry_safe(s, s2, &to_destroy, list) {
446 		debugfs_slab_release(s);
447 		kfence_shutdown_cache(s);
448 		kmem_cache_release(s);
449 	}
450 }
451 
452 static int shutdown_cache(struct kmem_cache *s)
453 {
454 	/* free asan quarantined objects */
455 	kasan_cache_shutdown(s);
456 
457 	if (__kmem_cache_shutdown(s) != 0)
458 		return -EBUSY;
459 
460 	list_del(&s->list);
461 
462 	if (s->flags & SLAB_TYPESAFE_BY_RCU) {
463 		list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
464 		schedule_work(&slab_caches_to_rcu_destroy_work);
465 	} else {
466 		kfence_shutdown_cache(s);
467 		debugfs_slab_release(s);
468 	}
469 
470 	return 0;
471 }
472 
473 void slab_kmem_cache_release(struct kmem_cache *s)
474 {
475 	__kmem_cache_release(s);
476 	kfree_const(s->name);
477 	kmem_cache_free(kmem_cache, s);
478 }
479 
480 void kmem_cache_destroy(struct kmem_cache *s)
481 {
482 	int refcnt;
483 	bool rcu_set;
484 
485 	if (unlikely(!s) || !kasan_check_byte(s))
486 		return;
487 
488 	cpus_read_lock();
489 	mutex_lock(&slab_mutex);
490 
491 	rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU;
492 
493 	refcnt = --s->refcount;
494 	if (refcnt)
495 		goto out_unlock;
496 
497 	WARN(shutdown_cache(s),
498 	     "%s %s: Slab cache still has objects when called from %pS",
499 	     __func__, s->name, (void *)_RET_IP_);
500 out_unlock:
501 	mutex_unlock(&slab_mutex);
502 	cpus_read_unlock();
503 	if (!refcnt && !rcu_set)
504 		kmem_cache_release(s);
505 }
506 EXPORT_SYMBOL(kmem_cache_destroy);
507 
508 /**
509  * kmem_cache_shrink - Shrink a cache.
510  * @cachep: The cache to shrink.
511  *
512  * Releases as many slabs as possible for a cache.
513  * To help debugging, a zero exit status indicates all slabs were released.
514  *
515  * Return: %0 if all slabs were released, non-zero otherwise
516  */
517 int kmem_cache_shrink(struct kmem_cache *cachep)
518 {
519 	kasan_cache_shrink(cachep);
520 
521 	return __kmem_cache_shrink(cachep);
522 }
523 EXPORT_SYMBOL(kmem_cache_shrink);
524 
525 bool slab_is_available(void)
526 {
527 	return slab_state >= UP;
528 }
529 
530 #ifdef CONFIG_PRINTK
531 /**
532  * kmem_valid_obj - does the pointer reference a valid slab object?
533  * @object: pointer to query.
534  *
535  * Return: %true if the pointer is to a not-yet-freed object from
536  * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
537  * is to an already-freed object, and %false otherwise.
538  */
539 bool kmem_valid_obj(void *object)
540 {
541 	struct folio *folio;
542 
543 	/* Some arches consider ZERO_SIZE_PTR to be a valid address. */
544 	if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
545 		return false;
546 	folio = virt_to_folio(object);
547 	return folio_test_slab(folio);
548 }
549 EXPORT_SYMBOL_GPL(kmem_valid_obj);
550 
551 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
552 {
553 	if (__kfence_obj_info(kpp, object, slab))
554 		return;
555 	__kmem_obj_info(kpp, object, slab);
556 }
557 
558 /**
559  * kmem_dump_obj - Print available slab provenance information
560  * @object: slab object for which to find provenance information.
561  *
562  * This function uses pr_cont(), so that the caller is expected to have
563  * printed out whatever preamble is appropriate.  The provenance information
564  * depends on the type of object and on how much debugging is enabled.
565  * For a slab-cache object, the fact that it is a slab object is printed,
566  * and, if available, the slab name, return address, and stack trace from
567  * the allocation and last free path of that object.
568  *
569  * This function will splat if passed a pointer to a non-slab object.
570  * If you are not sure what type of object you have, you should instead
571  * use mem_dump_obj().
572  */
573 void kmem_dump_obj(void *object)
574 {
575 	char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
576 	int i;
577 	struct slab *slab;
578 	unsigned long ptroffset;
579 	struct kmem_obj_info kp = { };
580 
581 	if (WARN_ON_ONCE(!virt_addr_valid(object)))
582 		return;
583 	slab = virt_to_slab(object);
584 	if (WARN_ON_ONCE(!slab)) {
585 		pr_cont(" non-slab memory.\n");
586 		return;
587 	}
588 	kmem_obj_info(&kp, object, slab);
589 	if (kp.kp_slab_cache)
590 		pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
591 	else
592 		pr_cont(" slab%s", cp);
593 	if (is_kfence_address(object))
594 		pr_cont(" (kfence)");
595 	if (kp.kp_objp)
596 		pr_cont(" start %px", kp.kp_objp);
597 	if (kp.kp_data_offset)
598 		pr_cont(" data offset %lu", kp.kp_data_offset);
599 	if (kp.kp_objp) {
600 		ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
601 		pr_cont(" pointer offset %lu", ptroffset);
602 	}
603 	if (kp.kp_slab_cache && kp.kp_slab_cache->object_size)
604 		pr_cont(" size %u", kp.kp_slab_cache->object_size);
605 	if (kp.kp_ret)
606 		pr_cont(" allocated at %pS\n", kp.kp_ret);
607 	else
608 		pr_cont("\n");
609 	for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
610 		if (!kp.kp_stack[i])
611 			break;
612 		pr_info("    %pS\n", kp.kp_stack[i]);
613 	}
614 
615 	if (kp.kp_free_stack[0])
616 		pr_cont(" Free path:\n");
617 
618 	for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
619 		if (!kp.kp_free_stack[i])
620 			break;
621 		pr_info("    %pS\n", kp.kp_free_stack[i]);
622 	}
623 
624 }
625 EXPORT_SYMBOL_GPL(kmem_dump_obj);
626 #endif
627 
628 #ifndef CONFIG_SLOB
629 /* Create a cache during boot when no slab services are available yet */
630 void __init create_boot_cache(struct kmem_cache *s, const char *name,
631 		unsigned int size, slab_flags_t flags,
632 		unsigned int useroffset, unsigned int usersize)
633 {
634 	int err;
635 	unsigned int align = ARCH_KMALLOC_MINALIGN;
636 
637 	s->name = name;
638 	s->size = s->object_size = size;
639 
640 	/*
641 	 * For power of two sizes, guarantee natural alignment for kmalloc
642 	 * caches, regardless of SL*B debugging options.
643 	 */
644 	if (is_power_of_2(size))
645 		align = max(align, size);
646 	s->align = calculate_alignment(flags, align, size);
647 
648 #ifdef CONFIG_HARDENED_USERCOPY
649 	s->useroffset = useroffset;
650 	s->usersize = usersize;
651 #endif
652 
653 	err = __kmem_cache_create(s, flags);
654 
655 	if (err)
656 		panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
657 					name, size, err);
658 
659 	s->refcount = -1;	/* Exempt from merging for now */
660 }
661 
662 struct kmem_cache *__init create_kmalloc_cache(const char *name,
663 		unsigned int size, slab_flags_t flags,
664 		unsigned int useroffset, unsigned int usersize)
665 {
666 	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
667 
668 	if (!s)
669 		panic("Out of memory when creating slab %s\n", name);
670 
671 	create_boot_cache(s, name, size, flags | SLAB_KMALLOC, useroffset,
672 								usersize);
673 	kasan_cache_create_kmalloc(s);
674 	list_add(&s->list, &slab_caches);
675 	s->refcount = 1;
676 	return s;
677 }
678 
679 struct kmem_cache *
680 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init =
681 { /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ };
682 EXPORT_SYMBOL(kmalloc_caches);
683 
684 /*
685  * Conversion table for small slabs sizes / 8 to the index in the
686  * kmalloc array. This is necessary for slabs < 192 since we have non power
687  * of two cache sizes there. The size of larger slabs can be determined using
688  * fls.
689  */
690 static u8 size_index[24] __ro_after_init = {
691 	3,	/* 8 */
692 	4,	/* 16 */
693 	5,	/* 24 */
694 	5,	/* 32 */
695 	6,	/* 40 */
696 	6,	/* 48 */
697 	6,	/* 56 */
698 	6,	/* 64 */
699 	1,	/* 72 */
700 	1,	/* 80 */
701 	1,	/* 88 */
702 	1,	/* 96 */
703 	7,	/* 104 */
704 	7,	/* 112 */
705 	7,	/* 120 */
706 	7,	/* 128 */
707 	2,	/* 136 */
708 	2,	/* 144 */
709 	2,	/* 152 */
710 	2,	/* 160 */
711 	2,	/* 168 */
712 	2,	/* 176 */
713 	2,	/* 184 */
714 	2	/* 192 */
715 };
716 
717 static inline unsigned int size_index_elem(unsigned int bytes)
718 {
719 	return (bytes - 1) / 8;
720 }
721 
722 /*
723  * Find the kmem_cache structure that serves a given size of
724  * allocation
725  */
726 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
727 {
728 	unsigned int index;
729 
730 	if (size <= 192) {
731 		if (!size)
732 			return ZERO_SIZE_PTR;
733 
734 		index = size_index[size_index_elem(size)];
735 	} else {
736 		if (WARN_ON_ONCE(size > KMALLOC_MAX_CACHE_SIZE))
737 			return NULL;
738 		index = fls(size - 1);
739 	}
740 
741 	return kmalloc_caches[kmalloc_type(flags)][index];
742 }
743 
744 size_t kmalloc_size_roundup(size_t size)
745 {
746 	struct kmem_cache *c;
747 
748 	/* Short-circuit the 0 size case. */
749 	if (unlikely(size == 0))
750 		return 0;
751 	/* Short-circuit saturated "too-large" case. */
752 	if (unlikely(size == SIZE_MAX))
753 		return SIZE_MAX;
754 	/* Above the smaller buckets, size is a multiple of page size. */
755 	if (size > KMALLOC_MAX_CACHE_SIZE)
756 		return PAGE_SIZE << get_order(size);
757 
758 	/* The flags don't matter since size_index is common to all. */
759 	c = kmalloc_slab(size, GFP_KERNEL);
760 	return c ? c->object_size : 0;
761 }
762 EXPORT_SYMBOL(kmalloc_size_roundup);
763 
764 #ifdef CONFIG_ZONE_DMA
765 #define KMALLOC_DMA_NAME(sz)	.name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
766 #else
767 #define KMALLOC_DMA_NAME(sz)
768 #endif
769 
770 #ifdef CONFIG_MEMCG_KMEM
771 #define KMALLOC_CGROUP_NAME(sz)	.name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
772 #else
773 #define KMALLOC_CGROUP_NAME(sz)
774 #endif
775 
776 #ifndef CONFIG_SLUB_TINY
777 #define KMALLOC_RCL_NAME(sz)	.name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
778 #else
779 #define KMALLOC_RCL_NAME(sz)
780 #endif
781 
782 #define INIT_KMALLOC_INFO(__size, __short_size)			\
783 {								\
784 	.name[KMALLOC_NORMAL]  = "kmalloc-" #__short_size,	\
785 	KMALLOC_RCL_NAME(__short_size)				\
786 	KMALLOC_CGROUP_NAME(__short_size)			\
787 	KMALLOC_DMA_NAME(__short_size)				\
788 	.size = __size,						\
789 }
790 
791 /*
792  * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
793  * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
794  * kmalloc-2M.
795  */
796 const struct kmalloc_info_struct kmalloc_info[] __initconst = {
797 	INIT_KMALLOC_INFO(0, 0),
798 	INIT_KMALLOC_INFO(96, 96),
799 	INIT_KMALLOC_INFO(192, 192),
800 	INIT_KMALLOC_INFO(8, 8),
801 	INIT_KMALLOC_INFO(16, 16),
802 	INIT_KMALLOC_INFO(32, 32),
803 	INIT_KMALLOC_INFO(64, 64),
804 	INIT_KMALLOC_INFO(128, 128),
805 	INIT_KMALLOC_INFO(256, 256),
806 	INIT_KMALLOC_INFO(512, 512),
807 	INIT_KMALLOC_INFO(1024, 1k),
808 	INIT_KMALLOC_INFO(2048, 2k),
809 	INIT_KMALLOC_INFO(4096, 4k),
810 	INIT_KMALLOC_INFO(8192, 8k),
811 	INIT_KMALLOC_INFO(16384, 16k),
812 	INIT_KMALLOC_INFO(32768, 32k),
813 	INIT_KMALLOC_INFO(65536, 64k),
814 	INIT_KMALLOC_INFO(131072, 128k),
815 	INIT_KMALLOC_INFO(262144, 256k),
816 	INIT_KMALLOC_INFO(524288, 512k),
817 	INIT_KMALLOC_INFO(1048576, 1M),
818 	INIT_KMALLOC_INFO(2097152, 2M)
819 };
820 
821 /*
822  * Patch up the size_index table if we have strange large alignment
823  * requirements for the kmalloc array. This is only the case for
824  * MIPS it seems. The standard arches will not generate any code here.
825  *
826  * Largest permitted alignment is 256 bytes due to the way we
827  * handle the index determination for the smaller caches.
828  *
829  * Make sure that nothing crazy happens if someone starts tinkering
830  * around with ARCH_KMALLOC_MINALIGN
831  */
832 void __init setup_kmalloc_cache_index_table(void)
833 {
834 	unsigned int i;
835 
836 	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
837 		!is_power_of_2(KMALLOC_MIN_SIZE));
838 
839 	for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
840 		unsigned int elem = size_index_elem(i);
841 
842 		if (elem >= ARRAY_SIZE(size_index))
843 			break;
844 		size_index[elem] = KMALLOC_SHIFT_LOW;
845 	}
846 
847 	if (KMALLOC_MIN_SIZE >= 64) {
848 		/*
849 		 * The 96 byte sized cache is not used if the alignment
850 		 * is 64 byte.
851 		 */
852 		for (i = 64 + 8; i <= 96; i += 8)
853 			size_index[size_index_elem(i)] = 7;
854 
855 	}
856 
857 	if (KMALLOC_MIN_SIZE >= 128) {
858 		/*
859 		 * The 192 byte sized cache is not used if the alignment
860 		 * is 128 byte. Redirect kmalloc to use the 256 byte cache
861 		 * instead.
862 		 */
863 		for (i = 128 + 8; i <= 192; i += 8)
864 			size_index[size_index_elem(i)] = 8;
865 	}
866 }
867 
868 static void __init
869 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
870 {
871 	if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
872 		flags |= SLAB_RECLAIM_ACCOUNT;
873 	} else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) {
874 		if (mem_cgroup_kmem_disabled()) {
875 			kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx];
876 			return;
877 		}
878 		flags |= SLAB_ACCOUNT;
879 	} else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {
880 		flags |= SLAB_CACHE_DMA;
881 	}
882 
883 	kmalloc_caches[type][idx] = create_kmalloc_cache(
884 					kmalloc_info[idx].name[type],
885 					kmalloc_info[idx].size, flags, 0,
886 					kmalloc_info[idx].size);
887 
888 	/*
889 	 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for
890 	 * KMALLOC_NORMAL caches.
891 	 */
892 	if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL))
893 		kmalloc_caches[type][idx]->refcount = -1;
894 }
895 
896 /*
897  * Create the kmalloc array. Some of the regular kmalloc arrays
898  * may already have been created because they were needed to
899  * enable allocations for slab creation.
900  */
901 void __init create_kmalloc_caches(slab_flags_t flags)
902 {
903 	int i;
904 	enum kmalloc_cache_type type;
905 
906 	/*
907 	 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined
908 	 */
909 	for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {
910 		for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
911 			if (!kmalloc_caches[type][i])
912 				new_kmalloc_cache(i, type, flags);
913 
914 			/*
915 			 * Caches that are not of the two-to-the-power-of size.
916 			 * These have to be created immediately after the
917 			 * earlier power of two caches
918 			 */
919 			if (KMALLOC_MIN_SIZE <= 32 && i == 6 &&
920 					!kmalloc_caches[type][1])
921 				new_kmalloc_cache(1, type, flags);
922 			if (KMALLOC_MIN_SIZE <= 64 && i == 7 &&
923 					!kmalloc_caches[type][2])
924 				new_kmalloc_cache(2, type, flags);
925 		}
926 	}
927 
928 	/* Kmalloc array is now usable */
929 	slab_state = UP;
930 }
931 
932 void free_large_kmalloc(struct folio *folio, void *object)
933 {
934 	unsigned int order = folio_order(folio);
935 
936 	if (WARN_ON_ONCE(order == 0))
937 		pr_warn_once("object pointer: 0x%p\n", object);
938 
939 	kmemleak_free(object);
940 	kasan_kfree_large(object);
941 	kmsan_kfree_large(object);
942 
943 	mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B,
944 			      -(PAGE_SIZE << order));
945 	__free_pages(folio_page(folio, 0), order);
946 }
947 
948 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node);
949 static __always_inline
950 void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
951 {
952 	struct kmem_cache *s;
953 	void *ret;
954 
955 	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
956 		ret = __kmalloc_large_node(size, flags, node);
957 		trace_kmalloc(caller, ret, size,
958 			      PAGE_SIZE << get_order(size), flags, node);
959 		return ret;
960 	}
961 
962 	s = kmalloc_slab(size, flags);
963 
964 	if (unlikely(ZERO_OR_NULL_PTR(s)))
965 		return s;
966 
967 	ret = __kmem_cache_alloc_node(s, flags, node, size, caller);
968 	ret = kasan_kmalloc(s, ret, size, flags);
969 	trace_kmalloc(caller, ret, size, s->size, flags, node);
970 	return ret;
971 }
972 
973 void *__kmalloc_node(size_t size, gfp_t flags, int node)
974 {
975 	return __do_kmalloc_node(size, flags, node, _RET_IP_);
976 }
977 EXPORT_SYMBOL(__kmalloc_node);
978 
979 void *__kmalloc(size_t size, gfp_t flags)
980 {
981 	return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_);
982 }
983 EXPORT_SYMBOL(__kmalloc);
984 
985 void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
986 				  int node, unsigned long caller)
987 {
988 	return __do_kmalloc_node(size, flags, node, caller);
989 }
990 EXPORT_SYMBOL(__kmalloc_node_track_caller);
991 
992 /**
993  * kfree - free previously allocated memory
994  * @object: pointer returned by kmalloc.
995  *
996  * If @object is NULL, no operation is performed.
997  *
998  * Don't free memory not originally allocated by kmalloc()
999  * or you will run into trouble.
1000  */
1001 void kfree(const void *object)
1002 {
1003 	struct folio *folio;
1004 	struct slab *slab;
1005 	struct kmem_cache *s;
1006 
1007 	trace_kfree(_RET_IP_, object);
1008 
1009 	if (unlikely(ZERO_OR_NULL_PTR(object)))
1010 		return;
1011 
1012 	folio = virt_to_folio(object);
1013 	if (unlikely(!folio_test_slab(folio))) {
1014 		free_large_kmalloc(folio, (void *)object);
1015 		return;
1016 	}
1017 
1018 	slab = folio_slab(folio);
1019 	s = slab->slab_cache;
1020 	__kmem_cache_free(s, (void *)object, _RET_IP_);
1021 }
1022 EXPORT_SYMBOL(kfree);
1023 
1024 /**
1025  * __ksize -- Report full size of underlying allocation
1026  * @object: pointer to the object
1027  *
1028  * This should only be used internally to query the true size of allocations.
1029  * It is not meant to be a way to discover the usable size of an allocation
1030  * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond
1031  * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS,
1032  * and/or FORTIFY_SOURCE.
1033  *
1034  * Return: size of the actual memory used by @object in bytes
1035  */
1036 size_t __ksize(const void *object)
1037 {
1038 	struct folio *folio;
1039 
1040 	if (unlikely(object == ZERO_SIZE_PTR))
1041 		return 0;
1042 
1043 	folio = virt_to_folio(object);
1044 
1045 	if (unlikely(!folio_test_slab(folio))) {
1046 		if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE))
1047 			return 0;
1048 		if (WARN_ON(object != folio_address(folio)))
1049 			return 0;
1050 		return folio_size(folio);
1051 	}
1052 
1053 #ifdef CONFIG_SLUB_DEBUG
1054 	skip_orig_size_check(folio_slab(folio)->slab_cache, object);
1055 #endif
1056 
1057 	return slab_ksize(folio_slab(folio)->slab_cache);
1058 }
1059 
1060 void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
1061 {
1062 	void *ret = __kmem_cache_alloc_node(s, gfpflags, NUMA_NO_NODE,
1063 					    size, _RET_IP_);
1064 
1065 	trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE);
1066 
1067 	ret = kasan_kmalloc(s, ret, size, gfpflags);
1068 	return ret;
1069 }
1070 EXPORT_SYMBOL(kmalloc_trace);
1071 
1072 void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
1073 			 int node, size_t size)
1074 {
1075 	void *ret = __kmem_cache_alloc_node(s, gfpflags, node, size, _RET_IP_);
1076 
1077 	trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node);
1078 
1079 	ret = kasan_kmalloc(s, ret, size, gfpflags);
1080 	return ret;
1081 }
1082 EXPORT_SYMBOL(kmalloc_node_trace);
1083 #endif /* !CONFIG_SLOB */
1084 
1085 gfp_t kmalloc_fix_flags(gfp_t flags)
1086 {
1087 	gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
1088 
1089 	flags &= ~GFP_SLAB_BUG_MASK;
1090 	pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
1091 			invalid_mask, &invalid_mask, flags, &flags);
1092 	dump_stack();
1093 
1094 	return flags;
1095 }
1096 
1097 /*
1098  * To avoid unnecessary overhead, we pass through large allocation requests
1099  * directly to the page allocator. We use __GFP_COMP, because we will need to
1100  * know the allocation order to free the pages properly in kfree.
1101  */
1102 
1103 static void *__kmalloc_large_node(size_t size, gfp_t flags, int node)
1104 {
1105 	struct page *page;
1106 	void *ptr = NULL;
1107 	unsigned int order = get_order(size);
1108 
1109 	if (unlikely(flags & GFP_SLAB_BUG_MASK))
1110 		flags = kmalloc_fix_flags(flags);
1111 
1112 	flags |= __GFP_COMP;
1113 	page = alloc_pages_node(node, flags, order);
1114 	if (page) {
1115 		ptr = page_address(page);
1116 		mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B,
1117 				      PAGE_SIZE << order);
1118 	}
1119 
1120 	ptr = kasan_kmalloc_large(ptr, size, flags);
1121 	/* As ptr might get tagged, call kmemleak hook after KASAN. */
1122 	kmemleak_alloc(ptr, size, 1, flags);
1123 	kmsan_kmalloc_large(ptr, size, flags);
1124 
1125 	return ptr;
1126 }
1127 
1128 void *kmalloc_large(size_t size, gfp_t flags)
1129 {
1130 	void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE);
1131 
1132 	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size),
1133 		      flags, NUMA_NO_NODE);
1134 	return ret;
1135 }
1136 EXPORT_SYMBOL(kmalloc_large);
1137 
1138 void *kmalloc_large_node(size_t size, gfp_t flags, int node)
1139 {
1140 	void *ret = __kmalloc_large_node(size, flags, node);
1141 
1142 	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size),
1143 		      flags, node);
1144 	return ret;
1145 }
1146 EXPORT_SYMBOL(kmalloc_large_node);
1147 
1148 #ifdef CONFIG_SLAB_FREELIST_RANDOM
1149 /* Randomize a generic freelist */
1150 static void freelist_randomize(struct rnd_state *state, unsigned int *list,
1151 			       unsigned int count)
1152 {
1153 	unsigned int rand;
1154 	unsigned int i;
1155 
1156 	for (i = 0; i < count; i++)
1157 		list[i] = i;
1158 
1159 	/* Fisher-Yates shuffle */
1160 	for (i = count - 1; i > 0; i--) {
1161 		rand = prandom_u32_state(state);
1162 		rand %= (i + 1);
1163 		swap(list[i], list[rand]);
1164 	}
1165 }
1166 
1167 /* Create a random sequence per cache */
1168 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
1169 				    gfp_t gfp)
1170 {
1171 	struct rnd_state state;
1172 
1173 	if (count < 2 || cachep->random_seq)
1174 		return 0;
1175 
1176 	cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
1177 	if (!cachep->random_seq)
1178 		return -ENOMEM;
1179 
1180 	/* Get best entropy at this stage of boot */
1181 	prandom_seed_state(&state, get_random_long());
1182 
1183 	freelist_randomize(&state, cachep->random_seq, count);
1184 	return 0;
1185 }
1186 
1187 /* Destroy the per-cache random freelist sequence */
1188 void cache_random_seq_destroy(struct kmem_cache *cachep)
1189 {
1190 	kfree(cachep->random_seq);
1191 	cachep->random_seq = NULL;
1192 }
1193 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1194 
1195 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
1196 #ifdef CONFIG_SLAB
1197 #define SLABINFO_RIGHTS (0600)
1198 #else
1199 #define SLABINFO_RIGHTS (0400)
1200 #endif
1201 
1202 static void print_slabinfo_header(struct seq_file *m)
1203 {
1204 	/*
1205 	 * Output format version, so at least we can change it
1206 	 * without _too_ many complaints.
1207 	 */
1208 #ifdef CONFIG_DEBUG_SLAB
1209 	seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
1210 #else
1211 	seq_puts(m, "slabinfo - version: 2.1\n");
1212 #endif
1213 	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1214 	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1215 	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1216 #ifdef CONFIG_DEBUG_SLAB
1217 	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
1218 	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
1219 #endif
1220 	seq_putc(m, '\n');
1221 }
1222 
1223 static void *slab_start(struct seq_file *m, loff_t *pos)
1224 {
1225 	mutex_lock(&slab_mutex);
1226 	return seq_list_start(&slab_caches, *pos);
1227 }
1228 
1229 static void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1230 {
1231 	return seq_list_next(p, &slab_caches, pos);
1232 }
1233 
1234 static void slab_stop(struct seq_file *m, void *p)
1235 {
1236 	mutex_unlock(&slab_mutex);
1237 }
1238 
1239 static void cache_show(struct kmem_cache *s, struct seq_file *m)
1240 {
1241 	struct slabinfo sinfo;
1242 
1243 	memset(&sinfo, 0, sizeof(sinfo));
1244 	get_slabinfo(s, &sinfo);
1245 
1246 	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1247 		   s->name, sinfo.active_objs, sinfo.num_objs, s->size,
1248 		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
1249 
1250 	seq_printf(m, " : tunables %4u %4u %4u",
1251 		   sinfo.limit, sinfo.batchcount, sinfo.shared);
1252 	seq_printf(m, " : slabdata %6lu %6lu %6lu",
1253 		   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1254 	slabinfo_show_stats(m, s);
1255 	seq_putc(m, '\n');
1256 }
1257 
1258 static int slab_show(struct seq_file *m, void *p)
1259 {
1260 	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1261 
1262 	if (p == slab_caches.next)
1263 		print_slabinfo_header(m);
1264 	cache_show(s, m);
1265 	return 0;
1266 }
1267 
1268 void dump_unreclaimable_slab(void)
1269 {
1270 	struct kmem_cache *s;
1271 	struct slabinfo sinfo;
1272 
1273 	/*
1274 	 * Here acquiring slab_mutex is risky since we don't prefer to get
1275 	 * sleep in oom path. But, without mutex hold, it may introduce a
1276 	 * risk of crash.
1277 	 * Use mutex_trylock to protect the list traverse, dump nothing
1278 	 * without acquiring the mutex.
1279 	 */
1280 	if (!mutex_trylock(&slab_mutex)) {
1281 		pr_warn("excessive unreclaimable slab but cannot dump stats\n");
1282 		return;
1283 	}
1284 
1285 	pr_info("Unreclaimable slab info:\n");
1286 	pr_info("Name                      Used          Total\n");
1287 
1288 	list_for_each_entry(s, &slab_caches, list) {
1289 		if (s->flags & SLAB_RECLAIM_ACCOUNT)
1290 			continue;
1291 
1292 		get_slabinfo(s, &sinfo);
1293 
1294 		if (sinfo.num_objs > 0)
1295 			pr_info("%-17s %10luKB %10luKB\n", s->name,
1296 				(sinfo.active_objs * s->size) / 1024,
1297 				(sinfo.num_objs * s->size) / 1024);
1298 	}
1299 	mutex_unlock(&slab_mutex);
1300 }
1301 
1302 /*
1303  * slabinfo_op - iterator that generates /proc/slabinfo
1304  *
1305  * Output layout:
1306  * cache-name
1307  * num-active-objs
1308  * total-objs
1309  * object size
1310  * num-active-slabs
1311  * total-slabs
1312  * num-pages-per-slab
1313  * + further values on SMP and with statistics enabled
1314  */
1315 static const struct seq_operations slabinfo_op = {
1316 	.start = slab_start,
1317 	.next = slab_next,
1318 	.stop = slab_stop,
1319 	.show = slab_show,
1320 };
1321 
1322 static int slabinfo_open(struct inode *inode, struct file *file)
1323 {
1324 	return seq_open(file, &slabinfo_op);
1325 }
1326 
1327 static const struct proc_ops slabinfo_proc_ops = {
1328 	.proc_flags	= PROC_ENTRY_PERMANENT,
1329 	.proc_open	= slabinfo_open,
1330 	.proc_read	= seq_read,
1331 	.proc_write	= slabinfo_write,
1332 	.proc_lseek	= seq_lseek,
1333 	.proc_release	= seq_release,
1334 };
1335 
1336 static int __init slab_proc_init(void)
1337 {
1338 	proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
1339 	return 0;
1340 }
1341 module_init(slab_proc_init);
1342 
1343 #endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
1344 
1345 static __always_inline __realloc_size(2) void *
1346 __do_krealloc(const void *p, size_t new_size, gfp_t flags)
1347 {
1348 	void *ret;
1349 	size_t ks;
1350 
1351 	/* Check for double-free before calling ksize. */
1352 	if (likely(!ZERO_OR_NULL_PTR(p))) {
1353 		if (!kasan_check_byte(p))
1354 			return NULL;
1355 		ks = ksize(p);
1356 	} else
1357 		ks = 0;
1358 
1359 	/* If the object still fits, repoison it precisely. */
1360 	if (ks >= new_size) {
1361 		p = kasan_krealloc((void *)p, new_size, flags);
1362 		return (void *)p;
1363 	}
1364 
1365 	ret = kmalloc_track_caller(new_size, flags);
1366 	if (ret && p) {
1367 		/* Disable KASAN checks as the object's redzone is accessed. */
1368 		kasan_disable_current();
1369 		memcpy(ret, kasan_reset_tag(p), ks);
1370 		kasan_enable_current();
1371 	}
1372 
1373 	return ret;
1374 }
1375 
1376 /**
1377  * krealloc - reallocate memory. The contents will remain unchanged.
1378  * @p: object to reallocate memory for.
1379  * @new_size: how many bytes of memory are required.
1380  * @flags: the type of memory to allocate.
1381  *
1382  * The contents of the object pointed to are preserved up to the
1383  * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored).
1384  * If @p is %NULL, krealloc() behaves exactly like kmalloc().  If @new_size
1385  * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
1386  *
1387  * Return: pointer to the allocated memory or %NULL in case of error
1388  */
1389 void *krealloc(const void *p, size_t new_size, gfp_t flags)
1390 {
1391 	void *ret;
1392 
1393 	if (unlikely(!new_size)) {
1394 		kfree(p);
1395 		return ZERO_SIZE_PTR;
1396 	}
1397 
1398 	ret = __do_krealloc(p, new_size, flags);
1399 	if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
1400 		kfree(p);
1401 
1402 	return ret;
1403 }
1404 EXPORT_SYMBOL(krealloc);
1405 
1406 /**
1407  * kfree_sensitive - Clear sensitive information in memory before freeing
1408  * @p: object to free memory of
1409  *
1410  * The memory of the object @p points to is zeroed before freed.
1411  * If @p is %NULL, kfree_sensitive() does nothing.
1412  *
1413  * Note: this function zeroes the whole allocated buffer which can be a good
1414  * deal bigger than the requested buffer size passed to kmalloc(). So be
1415  * careful when using this function in performance sensitive code.
1416  */
1417 void kfree_sensitive(const void *p)
1418 {
1419 	size_t ks;
1420 	void *mem = (void *)p;
1421 
1422 	ks = ksize(mem);
1423 	if (ks) {
1424 		kasan_unpoison_range(mem, ks);
1425 		memzero_explicit(mem, ks);
1426 	}
1427 	kfree(mem);
1428 }
1429 EXPORT_SYMBOL(kfree_sensitive);
1430 
1431 size_t ksize(const void *objp)
1432 {
1433 	/*
1434 	 * We need to first check that the pointer to the object is valid.
1435 	 * The KASAN report printed from ksize() is more useful, then when
1436 	 * it's printed later when the behaviour could be undefined due to
1437 	 * a potential use-after-free or double-free.
1438 	 *
1439 	 * We use kasan_check_byte(), which is supported for the hardware
1440 	 * tag-based KASAN mode, unlike kasan_check_read/write().
1441 	 *
1442 	 * If the pointed to memory is invalid, we return 0 to avoid users of
1443 	 * ksize() writing to and potentially corrupting the memory region.
1444 	 *
1445 	 * We want to perform the check before __ksize(), to avoid potentially
1446 	 * crashing in __ksize() due to accessing invalid metadata.
1447 	 */
1448 	if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
1449 		return 0;
1450 
1451 	return kfence_ksize(objp) ?: __ksize(objp);
1452 }
1453 EXPORT_SYMBOL(ksize);
1454 
1455 /* Tracepoints definitions. */
1456 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1457 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1458 EXPORT_TRACEPOINT_SYMBOL(kfree);
1459 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1460 
1461 int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
1462 {
1463 	if (__should_failslab(s, gfpflags))
1464 		return -ENOMEM;
1465 	return 0;
1466 }
1467 ALLOW_ERROR_INJECTION(should_failslab, ERRNO);
1468