1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SLUB: A slab allocator that limits cache line use instead of queuing
4  * objects in per cpu and per node lists.
5  *
6  * The allocator synchronizes using per slab locks or atomic operations
7  * and only uses a centralized lock to manage a pool of partial slabs.
8  *
9  * (C) 2007 SGI, Christoph Lameter
10  * (C) 2011 Linux Foundation, Christoph Lameter
11  */
12 
13 #include <linux/mm.h>
14 #include <linux/swap.h> /* struct reclaim_state */
15 #include <linux/module.h>
16 #include <linux/bit_spinlock.h>
17 #include <linux/interrupt.h>
18 #include <linux/swab.h>
19 #include <linux/bitops.h>
20 #include <linux/slab.h>
21 #include "slab.h"
22 #include <linux/proc_fs.h>
23 #include <linux/seq_file.h>
24 #include <linux/kasan.h>
25 #include <linux/kmsan.h>
26 #include <linux/cpu.h>
27 #include <linux/cpuset.h>
28 #include <linux/mempolicy.h>
29 #include <linux/ctype.h>
30 #include <linux/stackdepot.h>
31 #include <linux/debugobjects.h>
32 #include <linux/kallsyms.h>
33 #include <linux/kfence.h>
34 #include <linux/memory.h>
35 #include <linux/math64.h>
36 #include <linux/fault-inject.h>
37 #include <linux/stacktrace.h>
38 #include <linux/prefetch.h>
39 #include <linux/memcontrol.h>
40 #include <linux/random.h>
41 #include <kunit/test.h>
42 #include <linux/sort.h>
43 
44 #include <linux/debugfs.h>
45 #include <trace/events/kmem.h>
46 
47 #include "internal.h"
48 
49 /*
50  * Lock order:
51  *   1. slab_mutex (Global Mutex)
52  *   2. node->list_lock (Spinlock)
53  *   3. kmem_cache->cpu_slab->lock (Local lock)
54  *   4. slab_lock(slab) (Only on some arches)
55  *   5. object_map_lock (Only for debugging)
56  *
57  *   slab_mutex
58  *
59  *   The role of the slab_mutex is to protect the list of all the slabs
60  *   and to synchronize major metadata changes to slab cache structures.
61  *   Also synchronizes memory hotplug callbacks.
62  *
63  *   slab_lock
64  *
65  *   The slab_lock is a wrapper around the page lock, thus it is a bit
66  *   spinlock.
67  *
68  *   The slab_lock is only used on arches that do not have the ability
69  *   to do a cmpxchg_double. It only protects:
70  *
71  *	A. slab->freelist	-> List of free objects in a slab
72  *	B. slab->inuse		-> Number of objects in use
73  *	C. slab->objects	-> Number of objects in slab
74  *	D. slab->frozen		-> frozen state
75  *
76  *   Frozen slabs
77  *
78  *   If a slab is frozen then it is exempt from list management. It is not
79  *   on any list except per cpu partial list. The processor that froze the
80  *   slab is the one who can perform list operations on the slab. Other
81  *   processors may put objects onto the freelist but the processor that
82  *   froze the slab is the only one that can retrieve the objects from the
83  *   slab's freelist.
84  *
85  *   list_lock
86  *
87  *   The list_lock protects the partial and full list on each node and
88  *   the partial slab counter. If taken then no new slabs may be added or
89  *   removed from the lists nor make the number of partial slabs be modified.
90  *   (Note that the total number of slabs is an atomic value that may be
91  *   modified without taking the list lock).
92  *
93  *   The list_lock is a centralized lock and thus we avoid taking it as
94  *   much as possible. As long as SLUB does not have to handle partial
95  *   slabs, operations can continue without any centralized lock. F.e.
96  *   allocating a long series of objects that fill up slabs does not require
97  *   the list lock.
98  *
99  *   For debug caches, all allocations are forced to go through a list_lock
100  *   protected region to serialize against concurrent validation.
101  *
102  *   cpu_slab->lock local lock
103  *
104  *   This locks protect slowpath manipulation of all kmem_cache_cpu fields
105  *   except the stat counters. This is a percpu structure manipulated only by
106  *   the local cpu, so the lock protects against being preempted or interrupted
107  *   by an irq. Fast path operations rely on lockless operations instead.
108  *
109  *   On PREEMPT_RT, the local lock neither disables interrupts nor preemption
110  *   which means the lockless fastpath cannot be used as it might interfere with
111  *   an in-progress slow path operations. In this case the local lock is always
112  *   taken but it still utilizes the freelist for the common operations.
113  *
114  *   lockless fastpaths
115  *
116  *   The fast path allocation (slab_alloc_node()) and freeing (do_slab_free())
117  *   are fully lockless when satisfied from the percpu slab (and when
118  *   cmpxchg_double is possible to use, otherwise slab_lock is taken).
119  *   They also don't disable preemption or migration or irqs. They rely on
120  *   the transaction id (tid) field to detect being preempted or moved to
121  *   another cpu.
122  *
123  *   irq, preemption, migration considerations
124  *
125  *   Interrupts are disabled as part of list_lock or local_lock operations, or
126  *   around the slab_lock operation, in order to make the slab allocator safe
127  *   to use in the context of an irq.
128  *
129  *   In addition, preemption (or migration on PREEMPT_RT) is disabled in the
130  *   allocation slowpath, bulk allocation, and put_cpu_partial(), so that the
131  *   local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer
132  *   doesn't have to be revalidated in each section protected by the local lock.
133  *
134  * SLUB assigns one slab for allocation to each processor.
135  * Allocations only occur from these slabs called cpu slabs.
136  *
137  * Slabs with free elements are kept on a partial list and during regular
138  * operations no list for full slabs is used. If an object in a full slab is
139  * freed then the slab will show up again on the partial lists.
140  * We track full slabs for debugging purposes though because otherwise we
141  * cannot scan all objects.
142  *
143  * Slabs are freed when they become empty. Teardown and setup is
144  * minimal so we rely on the page allocators per cpu caches for
145  * fast frees and allocs.
146  *
147  * slab->frozen		The slab is frozen and exempt from list processing.
148  * 			This means that the slab is dedicated to a purpose
149  * 			such as satisfying allocations for a specific
150  * 			processor. Objects may be freed in the slab while
151  * 			it is frozen but slab_free will then skip the usual
152  * 			list operations. It is up to the processor holding
153  * 			the slab to integrate the slab into the slab lists
154  * 			when the slab is no longer needed.
155  *
156  * 			One use of this flag is to mark slabs that are
157  * 			used for allocations. Then such a slab becomes a cpu
158  * 			slab. The cpu slab may be equipped with an additional
159  * 			freelist that allows lockless access to
160  * 			free objects in addition to the regular freelist
161  * 			that requires the slab lock.
162  *
163  * SLAB_DEBUG_FLAGS	Slab requires special handling due to debug
164  * 			options set. This moves	slab handling out of
165  * 			the fast path and disables lockless freelists.
166  */
167 
168 /*
169  * We could simply use migrate_disable()/enable() but as long as it's a
170  * function call even on !PREEMPT_RT, use inline preempt_disable() there.
171  */
172 #ifndef CONFIG_PREEMPT_RT
173 #define slub_get_cpu_ptr(var)		get_cpu_ptr(var)
174 #define slub_put_cpu_ptr(var)		put_cpu_ptr(var)
175 #define USE_LOCKLESS_FAST_PATH()	(true)
176 #else
177 #define slub_get_cpu_ptr(var)		\
178 ({					\
179 	migrate_disable();		\
180 	this_cpu_ptr(var);		\
181 })
182 #define slub_put_cpu_ptr(var)		\
183 do {					\
184 	(void)(var);			\
185 	migrate_enable();		\
186 } while (0)
187 #define USE_LOCKLESS_FAST_PATH()	(false)
188 #endif
189 
190 #ifdef CONFIG_SLUB_DEBUG
191 #ifdef CONFIG_SLUB_DEBUG_ON
192 DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
193 #else
194 DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
195 #endif
196 #endif		/* CONFIG_SLUB_DEBUG */
197 
198 /* Structure holding parameters for get_partial() call chain */
199 struct partial_context {
200 	struct slab **slab;
201 	gfp_t flags;
202 	unsigned int orig_size;
203 };
204 
kmem_cache_debug(struct kmem_cache * s)205 static inline bool kmem_cache_debug(struct kmem_cache *s)
206 {
207 	return kmem_cache_debug_flags(s, SLAB_DEBUG_FLAGS);
208 }
209 
slub_debug_orig_size(struct kmem_cache * s)210 static inline bool slub_debug_orig_size(struct kmem_cache *s)
211 {
212 	return (kmem_cache_debug_flags(s, SLAB_STORE_USER) &&
213 			(s->flags & SLAB_KMALLOC));
214 }
215 
fixup_red_left(struct kmem_cache * s,void * p)216 void *fixup_red_left(struct kmem_cache *s, void *p)
217 {
218 	if (kmem_cache_debug_flags(s, SLAB_RED_ZONE))
219 		p += s->red_left_pad;
220 
221 	return p;
222 }
223 
kmem_cache_has_cpu_partial(struct kmem_cache * s)224 static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
225 {
226 #ifdef CONFIG_SLUB_CPU_PARTIAL
227 	return !kmem_cache_debug(s);
228 #else
229 	return false;
230 #endif
231 }
232 
233 /*
234  * Issues still to be resolved:
235  *
236  * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
237  *
238  * - Variable sizing of the per node arrays
239  */
240 
241 /* Enable to log cmpxchg failures */
242 #undef SLUB_DEBUG_CMPXCHG
243 
244 /*
245  * Minimum number of partial slabs. These will be left on the partial
246  * lists even if they are empty. kmem_cache_shrink may reclaim them.
247  */
248 #define MIN_PARTIAL 5
249 
250 /*
251  * Maximum number of desirable partial slabs.
252  * The existence of more partial slabs makes kmem_cache_shrink
253  * sort the partial list by the number of objects in use.
254  */
255 #define MAX_PARTIAL 10
256 
257 #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
258 				SLAB_POISON | SLAB_STORE_USER)
259 
260 /*
261  * These debug flags cannot use CMPXCHG because there might be consistency
262  * issues when checking or reading debug information
263  */
264 #define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \
265 				SLAB_TRACE)
266 
267 
268 /*
269  * Debugging flags that require metadata to be stored in the slab.  These get
270  * disabled when slub_debug=O is used and a cache's min order increases with
271  * metadata.
272  */
273 #define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
274 
275 #define OO_SHIFT	16
276 #define OO_MASK		((1 << OO_SHIFT) - 1)
277 #define MAX_OBJS_PER_PAGE	32767 /* since slab.objects is u15 */
278 
279 /* Internal SLUB flags */
280 /* Poison object */
281 #define __OBJECT_POISON		((slab_flags_t __force)0x80000000U)
282 /* Use cmpxchg_double */
283 #define __CMPXCHG_DOUBLE	((slab_flags_t __force)0x40000000U)
284 
285 /*
286  * Tracking user of a slab.
287  */
288 #define TRACK_ADDRS_COUNT 16
289 struct track {
290 	unsigned long addr;	/* Called from address */
291 #ifdef CONFIG_STACKDEPOT
292 	depot_stack_handle_t handle;
293 #endif
294 	int cpu;		/* Was running on cpu */
295 	int pid;		/* Pid context */
296 	unsigned long when;	/* When did the operation occur */
297 };
298 
299 enum track_item { TRACK_ALLOC, TRACK_FREE };
300 
301 #ifdef CONFIG_SYSFS
302 static int sysfs_slab_add(struct kmem_cache *);
303 static int sysfs_slab_alias(struct kmem_cache *, const char *);
304 #else
sysfs_slab_add(struct kmem_cache * s)305 static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
sysfs_slab_alias(struct kmem_cache * s,const char * p)306 static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
307 							{ return 0; }
308 #endif
309 
310 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG)
311 static void debugfs_slab_add(struct kmem_cache *);
312 #else
debugfs_slab_add(struct kmem_cache * s)313 static inline void debugfs_slab_add(struct kmem_cache *s) { }
314 #endif
315 
stat(const struct kmem_cache * s,enum stat_item si)316 static inline void stat(const struct kmem_cache *s, enum stat_item si)
317 {
318 #ifdef CONFIG_SLUB_STATS
319 	/*
320 	 * The rmw is racy on a preemptible kernel but this is acceptable, so
321 	 * avoid this_cpu_add()'s irq-disable overhead.
322 	 */
323 	raw_cpu_inc(s->cpu_slab->stat[si]);
324 #endif
325 }
326 
327 /*
328  * Tracks for which NUMA nodes we have kmem_cache_nodes allocated.
329  * Corresponds to node_state[N_NORMAL_MEMORY], but can temporarily
330  * differ during memory hotplug/hotremove operations.
331  * Protected by slab_mutex.
332  */
333 static nodemask_t slab_nodes;
334 
335 /*
336  * Workqueue used for flush_cpu_slab().
337  */
338 static struct workqueue_struct *flushwq;
339 
340 /********************************************************************
341  * 			Core slab cache functions
342  *******************************************************************/
343 
344 /*
345  * Returns freelist pointer (ptr). With hardening, this is obfuscated
346  * with an XOR of the address where the pointer is held and a per-cache
347  * random number.
348  */
freelist_ptr(const struct kmem_cache * s,void * ptr,unsigned long ptr_addr)349 static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr,
350 				 unsigned long ptr_addr)
351 {
352 #ifdef CONFIG_SLAB_FREELIST_HARDENED
353 	/*
354 	 * When CONFIG_KASAN_SW/HW_TAGS is enabled, ptr_addr might be tagged.
355 	 * Normally, this doesn't cause any issues, as both set_freepointer()
356 	 * and get_freepointer() are called with a pointer with the same tag.
357 	 * However, there are some issues with CONFIG_SLUB_DEBUG code. For
358 	 * example, when __free_slub() iterates over objects in a cache, it
359 	 * passes untagged pointers to check_object(). check_object() in turns
360 	 * calls get_freepointer() with an untagged pointer, which causes the
361 	 * freepointer to be restored incorrectly.
362 	 */
363 	return (void *)((unsigned long)ptr ^ s->random ^
364 			swab((unsigned long)kasan_reset_tag((void *)ptr_addr)));
365 #else
366 	return ptr;
367 #endif
368 }
369 
370 /* Returns the freelist pointer recorded at location ptr_addr. */
freelist_dereference(const struct kmem_cache * s,void * ptr_addr)371 static inline void *freelist_dereference(const struct kmem_cache *s,
372 					 void *ptr_addr)
373 {
374 	return freelist_ptr(s, (void *)*(unsigned long *)(ptr_addr),
375 			    (unsigned long)ptr_addr);
376 }
377 
get_freepointer(struct kmem_cache * s,void * object)378 static inline void *get_freepointer(struct kmem_cache *s, void *object)
379 {
380 	object = kasan_reset_tag(object);
381 	return freelist_dereference(s, object + s->offset);
382 }
383 
prefetch_freepointer(const struct kmem_cache * s,void * object)384 static void prefetch_freepointer(const struct kmem_cache *s, void *object)
385 {
386 	prefetchw(object + s->offset);
387 }
388 
389 /*
390  * When running under KMSAN, get_freepointer_safe() may return an uninitialized
391  * pointer value in the case the current thread loses the race for the next
392  * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in
393  * slab_alloc_node() will fail, so the uninitialized value won't be used, but
394  * KMSAN will still check all arguments of cmpxchg because of imperfect
395  * handling of inline assembly.
396  * To work around this problem, we apply __no_kmsan_checks to ensure that
397  * get_freepointer_safe() returns initialized memory.
398  */
399 __no_kmsan_checks
get_freepointer_safe(struct kmem_cache * s,void * object)400 static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
401 {
402 	unsigned long freepointer_addr;
403 	void *p;
404 
405 	if (!debug_pagealloc_enabled_static())
406 		return get_freepointer(s, object);
407 
408 	object = kasan_reset_tag(object);
409 	freepointer_addr = (unsigned long)object + s->offset;
410 	copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p));
411 	return freelist_ptr(s, p, freepointer_addr);
412 }
413 
set_freepointer(struct kmem_cache * s,void * object,void * fp)414 static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
415 {
416 	unsigned long freeptr_addr = (unsigned long)object + s->offset;
417 
418 #ifdef CONFIG_SLAB_FREELIST_HARDENED
419 	BUG_ON(object == fp); /* naive detection of double free or corruption */
420 #endif
421 
422 	freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr);
423 	*(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr);
424 }
425 
426 /* Loop over all objects in a slab */
427 #define for_each_object(__p, __s, __addr, __objects) \
428 	for (__p = fixup_red_left(__s, __addr); \
429 		__p < (__addr) + (__objects) * (__s)->size; \
430 		__p += (__s)->size)
431 
order_objects(unsigned int order,unsigned int size)432 static inline unsigned int order_objects(unsigned int order, unsigned int size)
433 {
434 	return ((unsigned int)PAGE_SIZE << order) / size;
435 }
436 
oo_make(unsigned int order,unsigned int size)437 static inline struct kmem_cache_order_objects oo_make(unsigned int order,
438 		unsigned int size)
439 {
440 	struct kmem_cache_order_objects x = {
441 		(order << OO_SHIFT) + order_objects(order, size)
442 	};
443 
444 	return x;
445 }
446 
oo_order(struct kmem_cache_order_objects x)447 static inline unsigned int oo_order(struct kmem_cache_order_objects x)
448 {
449 	return x.x >> OO_SHIFT;
450 }
451 
oo_objects(struct kmem_cache_order_objects x)452 static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
453 {
454 	return x.x & OO_MASK;
455 }
456 
457 #ifdef CONFIG_SLUB_CPU_PARTIAL
slub_set_cpu_partial(struct kmem_cache * s,unsigned int nr_objects)458 static void slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
459 {
460 	unsigned int nr_slabs;
461 
462 	s->cpu_partial = nr_objects;
463 
464 	/*
465 	 * We take the number of objects but actually limit the number of
466 	 * slabs on the per cpu partial list, in order to limit excessive
467 	 * growth of the list. For simplicity we assume that the slabs will
468 	 * be half-full.
469 	 */
470 	nr_slabs = DIV_ROUND_UP(nr_objects * 2, oo_objects(s->oo));
471 	s->cpu_partial_slabs = nr_slabs;
472 }
473 #else
474 static inline void
slub_set_cpu_partial(struct kmem_cache * s,unsigned int nr_objects)475 slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
476 {
477 }
478 #endif /* CONFIG_SLUB_CPU_PARTIAL */
479 
480 /*
481  * Per slab locking using the pagelock
482  */
slab_lock(struct slab * slab)483 static __always_inline void slab_lock(struct slab *slab)
484 {
485 	struct page *page = slab_page(slab);
486 
487 	VM_BUG_ON_PAGE(PageTail(page), page);
488 	bit_spin_lock(PG_locked, &page->flags);
489 }
490 
slab_unlock(struct slab * slab)491 static __always_inline void slab_unlock(struct slab *slab)
492 {
493 	struct page *page = slab_page(slab);
494 
495 	VM_BUG_ON_PAGE(PageTail(page), page);
496 	__bit_spin_unlock(PG_locked, &page->flags);
497 }
498 
499 /*
500  * Interrupts must be disabled (for the fallback code to work right), typically
501  * by an _irqsave() lock variant. On PREEMPT_RT the preempt_disable(), which is
502  * part of bit_spin_lock(), is sufficient because the policy is not to allow any
503  * allocation/ free operation in hardirq context. Therefore nothing can
504  * interrupt the operation.
505  */
__cmpxchg_double_slab(struct kmem_cache * s,struct slab * slab,void * freelist_old,unsigned long counters_old,void * freelist_new,unsigned long counters_new,const char * n)506 static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab,
507 		void *freelist_old, unsigned long counters_old,
508 		void *freelist_new, unsigned long counters_new,
509 		const char *n)
510 {
511 	if (USE_LOCKLESS_FAST_PATH())
512 		lockdep_assert_irqs_disabled();
513 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
514     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
515 	if (s->flags & __CMPXCHG_DOUBLE) {
516 		if (cmpxchg_double(&slab->freelist, &slab->counters,
517 				   freelist_old, counters_old,
518 				   freelist_new, counters_new))
519 			return true;
520 	} else
521 #endif
522 	{
523 		slab_lock(slab);
524 		if (slab->freelist == freelist_old &&
525 					slab->counters == counters_old) {
526 			slab->freelist = freelist_new;
527 			slab->counters = counters_new;
528 			slab_unlock(slab);
529 			return true;
530 		}
531 		slab_unlock(slab);
532 	}
533 
534 	cpu_relax();
535 	stat(s, CMPXCHG_DOUBLE_FAIL);
536 
537 #ifdef SLUB_DEBUG_CMPXCHG
538 	pr_info("%s %s: cmpxchg double redo ", n, s->name);
539 #endif
540 
541 	return false;
542 }
543 
cmpxchg_double_slab(struct kmem_cache * s,struct slab * slab,void * freelist_old,unsigned long counters_old,void * freelist_new,unsigned long counters_new,const char * n)544 static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab,
545 		void *freelist_old, unsigned long counters_old,
546 		void *freelist_new, unsigned long counters_new,
547 		const char *n)
548 {
549 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
550     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
551 	if (s->flags & __CMPXCHG_DOUBLE) {
552 		if (cmpxchg_double(&slab->freelist, &slab->counters,
553 				   freelist_old, counters_old,
554 				   freelist_new, counters_new))
555 			return true;
556 	} else
557 #endif
558 	{
559 		unsigned long flags;
560 
561 		local_irq_save(flags);
562 		slab_lock(slab);
563 		if (slab->freelist == freelist_old &&
564 					slab->counters == counters_old) {
565 			slab->freelist = freelist_new;
566 			slab->counters = counters_new;
567 			slab_unlock(slab);
568 			local_irq_restore(flags);
569 			return true;
570 		}
571 		slab_unlock(slab);
572 		local_irq_restore(flags);
573 	}
574 
575 	cpu_relax();
576 	stat(s, CMPXCHG_DOUBLE_FAIL);
577 
578 #ifdef SLUB_DEBUG_CMPXCHG
579 	pr_info("%s %s: cmpxchg double redo ", n, s->name);
580 #endif
581 
582 	return false;
583 }
584 
585 #ifdef CONFIG_SLUB_DEBUG
586 static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
587 static DEFINE_SPINLOCK(object_map_lock);
588 
__fill_map(unsigned long * obj_map,struct kmem_cache * s,struct slab * slab)589 static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
590 		       struct slab *slab)
591 {
592 	void *addr = slab_address(slab);
593 	void *p;
594 
595 	bitmap_zero(obj_map, slab->objects);
596 
597 	for (p = slab->freelist; p; p = get_freepointer(s, p))
598 		set_bit(__obj_to_index(s, addr, p), obj_map);
599 }
600 
601 #if IS_ENABLED(CONFIG_KUNIT)
slab_add_kunit_errors(void)602 static bool slab_add_kunit_errors(void)
603 {
604 	struct kunit_resource *resource;
605 
606 	if (likely(!current->kunit_test))
607 		return false;
608 
609 	resource = kunit_find_named_resource(current->kunit_test, "slab_errors");
610 	if (!resource)
611 		return false;
612 
613 	(*(int *)resource->data)++;
614 	kunit_put_resource(resource);
615 	return true;
616 }
617 #else
slab_add_kunit_errors(void)618 static inline bool slab_add_kunit_errors(void) { return false; }
619 #endif
620 
size_from_object(struct kmem_cache * s)621 static inline unsigned int size_from_object(struct kmem_cache *s)
622 {
623 	if (s->flags & SLAB_RED_ZONE)
624 		return s->size - s->red_left_pad;
625 
626 	return s->size;
627 }
628 
restore_red_left(struct kmem_cache * s,void * p)629 static inline void *restore_red_left(struct kmem_cache *s, void *p)
630 {
631 	if (s->flags & SLAB_RED_ZONE)
632 		p -= s->red_left_pad;
633 
634 	return p;
635 }
636 
637 /*
638  * Debug settings:
639  */
640 #if defined(CONFIG_SLUB_DEBUG_ON)
641 static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS;
642 #else
643 static slab_flags_t slub_debug;
644 #endif
645 
646 static char *slub_debug_string;
647 static int disable_higher_order_debug;
648 
649 /*
650  * slub is about to manipulate internal object metadata.  This memory lies
651  * outside the range of the allocated object, so accessing it would normally
652  * be reported by kasan as a bounds error.  metadata_access_enable() is used
653  * to tell kasan that these accesses are OK.
654  */
metadata_access_enable(void)655 static inline void metadata_access_enable(void)
656 {
657 	kasan_disable_current();
658 }
659 
metadata_access_disable(void)660 static inline void metadata_access_disable(void)
661 {
662 	kasan_enable_current();
663 }
664 
665 /*
666  * Object debugging
667  */
668 
669 /* Verify that a pointer has an address that is valid within a slab page */
check_valid_pointer(struct kmem_cache * s,struct slab * slab,void * object)670 static inline int check_valid_pointer(struct kmem_cache *s,
671 				struct slab *slab, void *object)
672 {
673 	void *base;
674 
675 	if (!object)
676 		return 1;
677 
678 	base = slab_address(slab);
679 	object = kasan_reset_tag(object);
680 	object = restore_red_left(s, object);
681 	if (object < base || object >= base + slab->objects * s->size ||
682 		(object - base) % s->size) {
683 		return 0;
684 	}
685 
686 	return 1;
687 }
688 
print_section(char * level,char * text,u8 * addr,unsigned int length)689 static void print_section(char *level, char *text, u8 *addr,
690 			  unsigned int length)
691 {
692 	metadata_access_enable();
693 	print_hex_dump(level, text, DUMP_PREFIX_ADDRESS,
694 			16, 1, kasan_reset_tag((void *)addr), length, 1);
695 	metadata_access_disable();
696 }
697 
698 /*
699  * See comment in calculate_sizes().
700  */
freeptr_outside_object(struct kmem_cache * s)701 static inline bool freeptr_outside_object(struct kmem_cache *s)
702 {
703 	return s->offset >= s->inuse;
704 }
705 
706 /*
707  * Return offset of the end of info block which is inuse + free pointer if
708  * not overlapping with object.
709  */
get_info_end(struct kmem_cache * s)710 static inline unsigned int get_info_end(struct kmem_cache *s)
711 {
712 	if (freeptr_outside_object(s))
713 		return s->inuse + sizeof(void *);
714 	else
715 		return s->inuse;
716 }
717 
get_track(struct kmem_cache * s,void * object,enum track_item alloc)718 static struct track *get_track(struct kmem_cache *s, void *object,
719 	enum track_item alloc)
720 {
721 	struct track *p;
722 
723 	p = object + get_info_end(s);
724 
725 	return kasan_reset_tag(p + alloc);
726 }
727 
728 #ifdef CONFIG_STACKDEPOT
set_track_prepare(void)729 static noinline depot_stack_handle_t set_track_prepare(void)
730 {
731 	depot_stack_handle_t handle;
732 	unsigned long entries[TRACK_ADDRS_COUNT];
733 	unsigned int nr_entries;
734 
735 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
736 	handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
737 
738 	return handle;
739 }
740 #else
set_track_prepare(void)741 static inline depot_stack_handle_t set_track_prepare(void)
742 {
743 	return 0;
744 }
745 #endif
746 
set_track_update(struct kmem_cache * s,void * object,enum track_item alloc,unsigned long addr,depot_stack_handle_t handle)747 static void set_track_update(struct kmem_cache *s, void *object,
748 			     enum track_item alloc, unsigned long addr,
749 			     depot_stack_handle_t handle)
750 {
751 	struct track *p = get_track(s, object, alloc);
752 
753 #ifdef CONFIG_STACKDEPOT
754 	p->handle = handle;
755 #endif
756 	p->addr = addr;
757 	p->cpu = smp_processor_id();
758 	p->pid = current->pid;
759 	p->when = jiffies;
760 }
761 
set_track(struct kmem_cache * s,void * object,enum track_item alloc,unsigned long addr)762 static __always_inline void set_track(struct kmem_cache *s, void *object,
763 				      enum track_item alloc, unsigned long addr)
764 {
765 	depot_stack_handle_t handle = set_track_prepare();
766 
767 	set_track_update(s, object, alloc, addr, handle);
768 }
769 
init_tracking(struct kmem_cache * s,void * object)770 static void init_tracking(struct kmem_cache *s, void *object)
771 {
772 	struct track *p;
773 
774 	if (!(s->flags & SLAB_STORE_USER))
775 		return;
776 
777 	p = get_track(s, object, TRACK_ALLOC);
778 	memset(p, 0, 2*sizeof(struct track));
779 }
780 
print_track(const char * s,struct track * t,unsigned long pr_time)781 static void print_track(const char *s, struct track *t, unsigned long pr_time)
782 {
783 	depot_stack_handle_t handle __maybe_unused;
784 
785 	if (!t->addr)
786 		return;
787 
788 	pr_err("%s in %pS age=%lu cpu=%u pid=%d\n",
789 	       s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
790 #ifdef CONFIG_STACKDEPOT
791 	handle = READ_ONCE(t->handle);
792 	if (handle)
793 		stack_depot_print(handle);
794 	else
795 		pr_err("object allocation/free stack trace missing\n");
796 #endif
797 }
798 
print_tracking(struct kmem_cache * s,void * object)799 void print_tracking(struct kmem_cache *s, void *object)
800 {
801 	unsigned long pr_time = jiffies;
802 	if (!(s->flags & SLAB_STORE_USER))
803 		return;
804 
805 	print_track("Allocated", get_track(s, object, TRACK_ALLOC), pr_time);
806 	print_track("Freed", get_track(s, object, TRACK_FREE), pr_time);
807 }
808 
print_slab_info(const struct slab * slab)809 static void print_slab_info(const struct slab *slab)
810 {
811 	struct folio *folio = (struct folio *)slab_folio(slab);
812 
813 	pr_err("Slab 0x%p objects=%u used=%u fp=0x%p flags=%pGp\n",
814 	       slab, slab->objects, slab->inuse, slab->freelist,
815 	       folio_flags(folio, 0));
816 }
817 
818 /*
819  * kmalloc caches has fixed sizes (mostly power of 2), and kmalloc() API
820  * family will round up the real request size to these fixed ones, so
821  * there could be an extra area than what is requested. Save the original
822  * request size in the meta data area, for better debug and sanity check.
823  */
set_orig_size(struct kmem_cache * s,void * object,unsigned int orig_size)824 static inline void set_orig_size(struct kmem_cache *s,
825 				void *object, unsigned int orig_size)
826 {
827 	void *p = kasan_reset_tag(object);
828 
829 	if (!slub_debug_orig_size(s))
830 		return;
831 
832 	p += get_info_end(s);
833 	p += sizeof(struct track) * 2;
834 
835 	*(unsigned int *)p = orig_size;
836 }
837 
get_orig_size(struct kmem_cache * s,void * object)838 static inline unsigned int get_orig_size(struct kmem_cache *s, void *object)
839 {
840 	void *p = kasan_reset_tag(object);
841 
842 	if (!slub_debug_orig_size(s))
843 		return s->object_size;
844 
845 	p += get_info_end(s);
846 	p += sizeof(struct track) * 2;
847 
848 	return *(unsigned int *)p;
849 }
850 
slab_bug(struct kmem_cache * s,char * fmt,...)851 static void slab_bug(struct kmem_cache *s, char *fmt, ...)
852 {
853 	struct va_format vaf;
854 	va_list args;
855 
856 	va_start(args, fmt);
857 	vaf.fmt = fmt;
858 	vaf.va = &args;
859 	pr_err("=============================================================================\n");
860 	pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
861 	pr_err("-----------------------------------------------------------------------------\n\n");
862 	va_end(args);
863 }
864 
865 __printf(2, 3)
slab_fix(struct kmem_cache * s,char * fmt,...)866 static void slab_fix(struct kmem_cache *s, char *fmt, ...)
867 {
868 	struct va_format vaf;
869 	va_list args;
870 
871 	if (slab_add_kunit_errors())
872 		return;
873 
874 	va_start(args, fmt);
875 	vaf.fmt = fmt;
876 	vaf.va = &args;
877 	pr_err("FIX %s: %pV\n", s->name, &vaf);
878 	va_end(args);
879 }
880 
print_trailer(struct kmem_cache * s,struct slab * slab,u8 * p)881 static void print_trailer(struct kmem_cache *s, struct slab *slab, u8 *p)
882 {
883 	unsigned int off;	/* Offset of last byte */
884 	u8 *addr = slab_address(slab);
885 
886 	print_tracking(s, p);
887 
888 	print_slab_info(slab);
889 
890 	pr_err("Object 0x%p @offset=%tu fp=0x%p\n\n",
891 	       p, p - addr, get_freepointer(s, p));
892 
893 	if (s->flags & SLAB_RED_ZONE)
894 		print_section(KERN_ERR, "Redzone  ", p - s->red_left_pad,
895 			      s->red_left_pad);
896 	else if (p > addr + 16)
897 		print_section(KERN_ERR, "Bytes b4 ", p - 16, 16);
898 
899 	print_section(KERN_ERR,         "Object   ", p,
900 		      min_t(unsigned int, s->object_size, PAGE_SIZE));
901 	if (s->flags & SLAB_RED_ZONE)
902 		print_section(KERN_ERR, "Redzone  ", p + s->object_size,
903 			s->inuse - s->object_size);
904 
905 	off = get_info_end(s);
906 
907 	if (s->flags & SLAB_STORE_USER)
908 		off += 2 * sizeof(struct track);
909 
910 	if (slub_debug_orig_size(s))
911 		off += sizeof(unsigned int);
912 
913 	off += kasan_metadata_size(s);
914 
915 	if (off != size_from_object(s))
916 		/* Beginning of the filler is the free pointer */
917 		print_section(KERN_ERR, "Padding  ", p + off,
918 			      size_from_object(s) - off);
919 
920 	dump_stack();
921 }
922 
object_err(struct kmem_cache * s,struct slab * slab,u8 * object,char * reason)923 static void object_err(struct kmem_cache *s, struct slab *slab,
924 			u8 *object, char *reason)
925 {
926 	if (slab_add_kunit_errors())
927 		return;
928 
929 	slab_bug(s, "%s", reason);
930 	print_trailer(s, slab, object);
931 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
932 }
933 
freelist_corrupted(struct kmem_cache * s,struct slab * slab,void ** freelist,void * nextfree)934 static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
935 			       void **freelist, void *nextfree)
936 {
937 	if ((s->flags & SLAB_CONSISTENCY_CHECKS) &&
938 	    !check_valid_pointer(s, slab, nextfree) && freelist) {
939 		object_err(s, slab, *freelist, "Freechain corrupt");
940 		*freelist = NULL;
941 		slab_fix(s, "Isolate corrupted freechain");
942 		return true;
943 	}
944 
945 	return false;
946 }
947 
slab_err(struct kmem_cache * s,struct slab * slab,const char * fmt,...)948 static __printf(3, 4) void slab_err(struct kmem_cache *s, struct slab *slab,
949 			const char *fmt, ...)
950 {
951 	va_list args;
952 	char buf[100];
953 
954 	if (slab_add_kunit_errors())
955 		return;
956 
957 	va_start(args, fmt);
958 	vsnprintf(buf, sizeof(buf), fmt, args);
959 	va_end(args);
960 	slab_bug(s, "%s", buf);
961 	print_slab_info(slab);
962 	dump_stack();
963 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
964 }
965 
init_object(struct kmem_cache * s,void * object,u8 val)966 static void init_object(struct kmem_cache *s, void *object, u8 val)
967 {
968 	u8 *p = kasan_reset_tag(object);
969 
970 	if (s->flags & SLAB_RED_ZONE)
971 		memset(p - s->red_left_pad, val, s->red_left_pad);
972 
973 	if (s->flags & __OBJECT_POISON) {
974 		memset(p, POISON_FREE, s->object_size - 1);
975 		p[s->object_size - 1] = POISON_END;
976 	}
977 
978 	if (s->flags & SLAB_RED_ZONE)
979 		memset(p + s->object_size, val, s->inuse - s->object_size);
980 }
981 
restore_bytes(struct kmem_cache * s,char * message,u8 data,void * from,void * to)982 static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
983 						void *from, void *to)
984 {
985 	slab_fix(s, "Restoring %s 0x%p-0x%p=0x%x", message, from, to - 1, data);
986 	memset(from, data, to - from);
987 }
988 
check_bytes_and_report(struct kmem_cache * s,struct slab * slab,u8 * object,char * what,u8 * start,unsigned int value,unsigned int bytes)989 static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab,
990 			u8 *object, char *what,
991 			u8 *start, unsigned int value, unsigned int bytes)
992 {
993 	u8 *fault;
994 	u8 *end;
995 	u8 *addr = slab_address(slab);
996 
997 	metadata_access_enable();
998 	fault = memchr_inv(kasan_reset_tag(start), value, bytes);
999 	metadata_access_disable();
1000 	if (!fault)
1001 		return 1;
1002 
1003 	end = start + bytes;
1004 	while (end > fault && end[-1] == value)
1005 		end--;
1006 
1007 	if (slab_add_kunit_errors())
1008 		goto skip_bug_print;
1009 
1010 	slab_bug(s, "%s overwritten", what);
1011 	pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n",
1012 					fault, end - 1, fault - addr,
1013 					fault[0], value);
1014 	print_trailer(s, slab, object);
1015 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
1016 
1017 skip_bug_print:
1018 	restore_bytes(s, what, value, fault, end);
1019 	return 0;
1020 }
1021 
1022 /*
1023  * Object layout:
1024  *
1025  * object address
1026  * 	Bytes of the object to be managed.
1027  * 	If the freepointer may overlay the object then the free
1028  *	pointer is at the middle of the object.
1029  *
1030  * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
1031  * 	0xa5 (POISON_END)
1032  *
1033  * object + s->object_size
1034  * 	Padding to reach word boundary. This is also used for Redzoning.
1035  * 	Padding is extended by another word if Redzoning is enabled and
1036  * 	object_size == inuse.
1037  *
1038  * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
1039  * 	0xcc (RED_ACTIVE) for objects in use.
1040  *
1041  * object + s->inuse
1042  * 	Meta data starts here.
1043  *
1044  * 	A. Free pointer (if we cannot overwrite object on free)
1045  * 	B. Tracking data for SLAB_STORE_USER
1046  *	C. Original request size for kmalloc object (SLAB_STORE_USER enabled)
1047  *	D. Padding to reach required alignment boundary or at minimum
1048  * 		one word if debugging is on to be able to detect writes
1049  * 		before the word boundary.
1050  *
1051  *	Padding is done using 0x5a (POISON_INUSE)
1052  *
1053  * object + s->size
1054  * 	Nothing is used beyond s->size.
1055  *
1056  * If slabcaches are merged then the object_size and inuse boundaries are mostly
1057  * ignored. And therefore no slab options that rely on these boundaries
1058  * may be used with merged slabcaches.
1059  */
1060 
check_pad_bytes(struct kmem_cache * s,struct slab * slab,u8 * p)1061 static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p)
1062 {
1063 	unsigned long off = get_info_end(s);	/* The end of info */
1064 
1065 	if (s->flags & SLAB_STORE_USER) {
1066 		/* We also have user information there */
1067 		off += 2 * sizeof(struct track);
1068 
1069 		if (s->flags & SLAB_KMALLOC)
1070 			off += sizeof(unsigned int);
1071 	}
1072 
1073 	off += kasan_metadata_size(s);
1074 
1075 	if (size_from_object(s) == off)
1076 		return 1;
1077 
1078 	return check_bytes_and_report(s, slab, p, "Object padding",
1079 			p + off, POISON_INUSE, size_from_object(s) - off);
1080 }
1081 
1082 /* Check the pad bytes at the end of a slab page */
slab_pad_check(struct kmem_cache * s,struct slab * slab)1083 static void slab_pad_check(struct kmem_cache *s, struct slab *slab)
1084 {
1085 	u8 *start;
1086 	u8 *fault;
1087 	u8 *end;
1088 	u8 *pad;
1089 	int length;
1090 	int remainder;
1091 
1092 	if (!(s->flags & SLAB_POISON))
1093 		return;
1094 
1095 	start = slab_address(slab);
1096 	length = slab_size(slab);
1097 	end = start + length;
1098 	remainder = length % s->size;
1099 	if (!remainder)
1100 		return;
1101 
1102 	pad = end - remainder;
1103 	metadata_access_enable();
1104 	fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder);
1105 	metadata_access_disable();
1106 	if (!fault)
1107 		return;
1108 	while (end > fault && end[-1] == POISON_INUSE)
1109 		end--;
1110 
1111 	slab_err(s, slab, "Padding overwritten. 0x%p-0x%p @offset=%tu",
1112 			fault, end - 1, fault - start);
1113 	print_section(KERN_ERR, "Padding ", pad, remainder);
1114 
1115 	restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
1116 }
1117 
check_object(struct kmem_cache * s,struct slab * slab,void * object,u8 val)1118 static int check_object(struct kmem_cache *s, struct slab *slab,
1119 					void *object, u8 val)
1120 {
1121 	u8 *p = object;
1122 	u8 *endobject = object + s->object_size;
1123 
1124 	if (s->flags & SLAB_RED_ZONE) {
1125 		if (!check_bytes_and_report(s, slab, object, "Left Redzone",
1126 			object - s->red_left_pad, val, s->red_left_pad))
1127 			return 0;
1128 
1129 		if (!check_bytes_and_report(s, slab, object, "Right Redzone",
1130 			endobject, val, s->inuse - s->object_size))
1131 			return 0;
1132 	} else {
1133 		if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
1134 			check_bytes_and_report(s, slab, p, "Alignment padding",
1135 				endobject, POISON_INUSE,
1136 				s->inuse - s->object_size);
1137 		}
1138 	}
1139 
1140 	if (s->flags & SLAB_POISON) {
1141 		if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
1142 			(!check_bytes_and_report(s, slab, p, "Poison", p,
1143 					POISON_FREE, s->object_size - 1) ||
1144 			 !check_bytes_and_report(s, slab, p, "End Poison",
1145 				p + s->object_size - 1, POISON_END, 1)))
1146 			return 0;
1147 		/*
1148 		 * check_pad_bytes cleans up on its own.
1149 		 */
1150 		check_pad_bytes(s, slab, p);
1151 	}
1152 
1153 	if (!freeptr_outside_object(s) && val == SLUB_RED_ACTIVE)
1154 		/*
1155 		 * Object and freepointer overlap. Cannot check
1156 		 * freepointer while object is allocated.
1157 		 */
1158 		return 1;
1159 
1160 	/* Check free pointer validity */
1161 	if (!check_valid_pointer(s, slab, get_freepointer(s, p))) {
1162 		object_err(s, slab, p, "Freepointer corrupt");
1163 		/*
1164 		 * No choice but to zap it and thus lose the remainder
1165 		 * of the free objects in this slab. May cause
1166 		 * another error because the object count is now wrong.
1167 		 */
1168 		set_freepointer(s, p, NULL);
1169 		return 0;
1170 	}
1171 	return 1;
1172 }
1173 
check_slab(struct kmem_cache * s,struct slab * slab)1174 static int check_slab(struct kmem_cache *s, struct slab *slab)
1175 {
1176 	int maxobj;
1177 
1178 	if (!folio_test_slab(slab_folio(slab))) {
1179 		slab_err(s, slab, "Not a valid slab page");
1180 		return 0;
1181 	}
1182 
1183 	maxobj = order_objects(slab_order(slab), s->size);
1184 	if (slab->objects > maxobj) {
1185 		slab_err(s, slab, "objects %u > max %u",
1186 			slab->objects, maxobj);
1187 		return 0;
1188 	}
1189 	if (slab->inuse > slab->objects) {
1190 		slab_err(s, slab, "inuse %u > max %u",
1191 			slab->inuse, slab->objects);
1192 		return 0;
1193 	}
1194 	/* Slab_pad_check fixes things up after itself */
1195 	slab_pad_check(s, slab);
1196 	return 1;
1197 }
1198 
1199 /*
1200  * Determine if a certain object in a slab is on the freelist. Must hold the
1201  * slab lock to guarantee that the chains are in a consistent state.
1202  */
on_freelist(struct kmem_cache * s,struct slab * slab,void * search)1203 static int on_freelist(struct kmem_cache *s, struct slab *slab, void *search)
1204 {
1205 	int nr = 0;
1206 	void *fp;
1207 	void *object = NULL;
1208 	int max_objects;
1209 
1210 	fp = slab->freelist;
1211 	while (fp && nr <= slab->objects) {
1212 		if (fp == search)
1213 			return 1;
1214 		if (!check_valid_pointer(s, slab, fp)) {
1215 			if (object) {
1216 				object_err(s, slab, object,
1217 					"Freechain corrupt");
1218 				set_freepointer(s, object, NULL);
1219 			} else {
1220 				slab_err(s, slab, "Freepointer corrupt");
1221 				slab->freelist = NULL;
1222 				slab->inuse = slab->objects;
1223 				slab_fix(s, "Freelist cleared");
1224 				return 0;
1225 			}
1226 			break;
1227 		}
1228 		object = fp;
1229 		fp = get_freepointer(s, object);
1230 		nr++;
1231 	}
1232 
1233 	max_objects = order_objects(slab_order(slab), s->size);
1234 	if (max_objects > MAX_OBJS_PER_PAGE)
1235 		max_objects = MAX_OBJS_PER_PAGE;
1236 
1237 	if (slab->objects != max_objects) {
1238 		slab_err(s, slab, "Wrong number of objects. Found %d but should be %d",
1239 			 slab->objects, max_objects);
1240 		slab->objects = max_objects;
1241 		slab_fix(s, "Number of objects adjusted");
1242 	}
1243 	if (slab->inuse != slab->objects - nr) {
1244 		slab_err(s, slab, "Wrong object count. Counter is %d but counted were %d",
1245 			 slab->inuse, slab->objects - nr);
1246 		slab->inuse = slab->objects - nr;
1247 		slab_fix(s, "Object count adjusted");
1248 	}
1249 	return search == NULL;
1250 }
1251 
trace(struct kmem_cache * s,struct slab * slab,void * object,int alloc)1252 static void trace(struct kmem_cache *s, struct slab *slab, void *object,
1253 								int alloc)
1254 {
1255 	if (s->flags & SLAB_TRACE) {
1256 		pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
1257 			s->name,
1258 			alloc ? "alloc" : "free",
1259 			object, slab->inuse,
1260 			slab->freelist);
1261 
1262 		if (!alloc)
1263 			print_section(KERN_INFO, "Object ", (void *)object,
1264 					s->object_size);
1265 
1266 		dump_stack();
1267 	}
1268 }
1269 
1270 /*
1271  * Tracking of fully allocated slabs for debugging purposes.
1272  */
add_full(struct kmem_cache * s,struct kmem_cache_node * n,struct slab * slab)1273 static void add_full(struct kmem_cache *s,
1274 	struct kmem_cache_node *n, struct slab *slab)
1275 {
1276 	if (!(s->flags & SLAB_STORE_USER))
1277 		return;
1278 
1279 	lockdep_assert_held(&n->list_lock);
1280 	list_add(&slab->slab_list, &n->full);
1281 }
1282 
remove_full(struct kmem_cache * s,struct kmem_cache_node * n,struct slab * slab)1283 static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab)
1284 {
1285 	if (!(s->flags & SLAB_STORE_USER))
1286 		return;
1287 
1288 	lockdep_assert_held(&n->list_lock);
1289 	list_del(&slab->slab_list);
1290 }
1291 
1292 /* Tracking of the number of slabs for debugging purposes */
slabs_node(struct kmem_cache * s,int node)1293 static inline unsigned long slabs_node(struct kmem_cache *s, int node)
1294 {
1295 	struct kmem_cache_node *n = get_node(s, node);
1296 
1297 	return atomic_long_read(&n->nr_slabs);
1298 }
1299 
node_nr_slabs(struct kmem_cache_node * n)1300 static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
1301 {
1302 	return atomic_long_read(&n->nr_slabs);
1303 }
1304 
inc_slabs_node(struct kmem_cache * s,int node,int objects)1305 static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
1306 {
1307 	struct kmem_cache_node *n = get_node(s, node);
1308 
1309 	/*
1310 	 * May be called early in order to allocate a slab for the
1311 	 * kmem_cache_node structure. Solve the chicken-egg
1312 	 * dilemma by deferring the increment of the count during
1313 	 * bootstrap (see early_kmem_cache_node_alloc).
1314 	 */
1315 	if (likely(n)) {
1316 		atomic_long_inc(&n->nr_slabs);
1317 		atomic_long_add(objects, &n->total_objects);
1318 	}
1319 }
dec_slabs_node(struct kmem_cache * s,int node,int objects)1320 static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
1321 {
1322 	struct kmem_cache_node *n = get_node(s, node);
1323 
1324 	atomic_long_dec(&n->nr_slabs);
1325 	atomic_long_sub(objects, &n->total_objects);
1326 }
1327 
1328 /* Object debug checks for alloc/free paths */
setup_object_debug(struct kmem_cache * s,void * object)1329 static void setup_object_debug(struct kmem_cache *s, void *object)
1330 {
1331 	if (!kmem_cache_debug_flags(s, SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON))
1332 		return;
1333 
1334 	init_object(s, object, SLUB_RED_INACTIVE);
1335 	init_tracking(s, object);
1336 }
1337 
1338 static
setup_slab_debug(struct kmem_cache * s,struct slab * slab,void * addr)1339 void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr)
1340 {
1341 	if (!kmem_cache_debug_flags(s, SLAB_POISON))
1342 		return;
1343 
1344 	metadata_access_enable();
1345 	memset(kasan_reset_tag(addr), POISON_INUSE, slab_size(slab));
1346 	metadata_access_disable();
1347 }
1348 
alloc_consistency_checks(struct kmem_cache * s,struct slab * slab,void * object)1349 static inline int alloc_consistency_checks(struct kmem_cache *s,
1350 					struct slab *slab, void *object)
1351 {
1352 	if (!check_slab(s, slab))
1353 		return 0;
1354 
1355 	if (!check_valid_pointer(s, slab, object)) {
1356 		object_err(s, slab, object, "Freelist Pointer check fails");
1357 		return 0;
1358 	}
1359 
1360 	if (!check_object(s, slab, object, SLUB_RED_INACTIVE))
1361 		return 0;
1362 
1363 	return 1;
1364 }
1365 
alloc_debug_processing(struct kmem_cache * s,struct slab * slab,void * object,int orig_size)1366 static noinline int alloc_debug_processing(struct kmem_cache *s,
1367 			struct slab *slab, void *object, int orig_size)
1368 {
1369 	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
1370 		if (!alloc_consistency_checks(s, slab, object))
1371 			goto bad;
1372 	}
1373 
1374 	/* Success. Perform special debug activities for allocs */
1375 	trace(s, slab, object, 1);
1376 	set_orig_size(s, object, orig_size);
1377 	init_object(s, object, SLUB_RED_ACTIVE);
1378 	return 1;
1379 
1380 bad:
1381 	if (folio_test_slab(slab_folio(slab))) {
1382 		/*
1383 		 * If this is a slab page then lets do the best we can
1384 		 * to avoid issues in the future. Marking all objects
1385 		 * as used avoids touching the remaining objects.
1386 		 */
1387 		slab_fix(s, "Marking all objects used");
1388 		slab->inuse = slab->objects;
1389 		slab->freelist = NULL;
1390 	}
1391 	return 0;
1392 }
1393 
free_consistency_checks(struct kmem_cache * s,struct slab * slab,void * object,unsigned long addr)1394 static inline int free_consistency_checks(struct kmem_cache *s,
1395 		struct slab *slab, void *object, unsigned long addr)
1396 {
1397 	if (!check_valid_pointer(s, slab, object)) {
1398 		slab_err(s, slab, "Invalid object pointer 0x%p", object);
1399 		return 0;
1400 	}
1401 
1402 	if (on_freelist(s, slab, object)) {
1403 		object_err(s, slab, object, "Object already free");
1404 		return 0;
1405 	}
1406 
1407 	if (!check_object(s, slab, object, SLUB_RED_ACTIVE))
1408 		return 0;
1409 
1410 	if (unlikely(s != slab->slab_cache)) {
1411 		if (!folio_test_slab(slab_folio(slab))) {
1412 			slab_err(s, slab, "Attempt to free object(0x%p) outside of slab",
1413 				 object);
1414 		} else if (!slab->slab_cache) {
1415 			pr_err("SLUB <none>: no slab for object 0x%p.\n",
1416 			       object);
1417 			dump_stack();
1418 		} else
1419 			object_err(s, slab, object,
1420 					"page slab pointer corrupt.");
1421 		return 0;
1422 	}
1423 	return 1;
1424 }
1425 
1426 /*
1427  * Parse a block of slub_debug options. Blocks are delimited by ';'
1428  *
1429  * @str:    start of block
1430  * @flags:  returns parsed flags, or DEBUG_DEFAULT_FLAGS if none specified
1431  * @slabs:  return start of list of slabs, or NULL when there's no list
1432  * @init:   assume this is initial parsing and not per-kmem-create parsing
1433  *
1434  * returns the start of next block if there's any, or NULL
1435  */
1436 static char *
parse_slub_debug_flags(char * str,slab_flags_t * flags,char ** slabs,bool init)1437 parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init)
1438 {
1439 	bool higher_order_disable = false;
1440 
1441 	/* Skip any completely empty blocks */
1442 	while (*str && *str == ';')
1443 		str++;
1444 
1445 	if (*str == ',') {
1446 		/*
1447 		 * No options but restriction on slabs. This means full
1448 		 * debugging for slabs matching a pattern.
1449 		 */
1450 		*flags = DEBUG_DEFAULT_FLAGS;
1451 		goto check_slabs;
1452 	}
1453 	*flags = 0;
1454 
1455 	/* Determine which debug features should be switched on */
1456 	for (; *str && *str != ',' && *str != ';'; str++) {
1457 		switch (tolower(*str)) {
1458 		case '-':
1459 			*flags = 0;
1460 			break;
1461 		case 'f':
1462 			*flags |= SLAB_CONSISTENCY_CHECKS;
1463 			break;
1464 		case 'z':
1465 			*flags |= SLAB_RED_ZONE;
1466 			break;
1467 		case 'p':
1468 			*flags |= SLAB_POISON;
1469 			break;
1470 		case 'u':
1471 			*flags |= SLAB_STORE_USER;
1472 			break;
1473 		case 't':
1474 			*flags |= SLAB_TRACE;
1475 			break;
1476 		case 'a':
1477 			*flags |= SLAB_FAILSLAB;
1478 			break;
1479 		case 'o':
1480 			/*
1481 			 * Avoid enabling debugging on caches if its minimum
1482 			 * order would increase as a result.
1483 			 */
1484 			higher_order_disable = true;
1485 			break;
1486 		default:
1487 			if (init)
1488 				pr_err("slub_debug option '%c' unknown. skipped\n", *str);
1489 		}
1490 	}
1491 check_slabs:
1492 	if (*str == ',')
1493 		*slabs = ++str;
1494 	else
1495 		*slabs = NULL;
1496 
1497 	/* Skip over the slab list */
1498 	while (*str && *str != ';')
1499 		str++;
1500 
1501 	/* Skip any completely empty blocks */
1502 	while (*str && *str == ';')
1503 		str++;
1504 
1505 	if (init && higher_order_disable)
1506 		disable_higher_order_debug = 1;
1507 
1508 	if (*str)
1509 		return str;
1510 	else
1511 		return NULL;
1512 }
1513 
setup_slub_debug(char * str)1514 static int __init setup_slub_debug(char *str)
1515 {
1516 	slab_flags_t flags;
1517 	slab_flags_t global_flags;
1518 	char *saved_str;
1519 	char *slab_list;
1520 	bool global_slub_debug_changed = false;
1521 	bool slab_list_specified = false;
1522 
1523 	global_flags = DEBUG_DEFAULT_FLAGS;
1524 	if (*str++ != '=' || !*str)
1525 		/*
1526 		 * No options specified. Switch on full debugging.
1527 		 */
1528 		goto out;
1529 
1530 	saved_str = str;
1531 	while (str) {
1532 		str = parse_slub_debug_flags(str, &flags, &slab_list, true);
1533 
1534 		if (!slab_list) {
1535 			global_flags = flags;
1536 			global_slub_debug_changed = true;
1537 		} else {
1538 			slab_list_specified = true;
1539 			if (flags & SLAB_STORE_USER)
1540 				stack_depot_want_early_init();
1541 		}
1542 	}
1543 
1544 	/*
1545 	 * For backwards compatibility, a single list of flags with list of
1546 	 * slabs means debugging is only changed for those slabs, so the global
1547 	 * slub_debug should be unchanged (0 or DEBUG_DEFAULT_FLAGS, depending
1548 	 * on CONFIG_SLUB_DEBUG_ON). We can extended that to multiple lists as
1549 	 * long as there is no option specifying flags without a slab list.
1550 	 */
1551 	if (slab_list_specified) {
1552 		if (!global_slub_debug_changed)
1553 			global_flags = slub_debug;
1554 		slub_debug_string = saved_str;
1555 	}
1556 out:
1557 	slub_debug = global_flags;
1558 	if (slub_debug & SLAB_STORE_USER)
1559 		stack_depot_want_early_init();
1560 	if (slub_debug != 0 || slub_debug_string)
1561 		static_branch_enable(&slub_debug_enabled);
1562 	else
1563 		static_branch_disable(&slub_debug_enabled);
1564 	if ((static_branch_unlikely(&init_on_alloc) ||
1565 	     static_branch_unlikely(&init_on_free)) &&
1566 	    (slub_debug & SLAB_POISON))
1567 		pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n");
1568 	return 1;
1569 }
1570 
1571 __setup("slub_debug", setup_slub_debug);
1572 
1573 /*
1574  * kmem_cache_flags - apply debugging options to the cache
1575  * @object_size:	the size of an object without meta data
1576  * @flags:		flags to set
1577  * @name:		name of the cache
1578  *
1579  * Debug option(s) are applied to @flags. In addition to the debug
1580  * option(s), if a slab name (or multiple) is specified i.e.
1581  * slub_debug=<Debug-Options>,<slab name1>,<slab name2> ...
1582  * then only the select slabs will receive the debug option(s).
1583  */
kmem_cache_flags(unsigned int object_size,slab_flags_t flags,const char * name)1584 slab_flags_t kmem_cache_flags(unsigned int object_size,
1585 	slab_flags_t flags, const char *name)
1586 {
1587 	char *iter;
1588 	size_t len;
1589 	char *next_block;
1590 	slab_flags_t block_flags;
1591 	slab_flags_t slub_debug_local = slub_debug;
1592 
1593 	if (flags & SLAB_NO_USER_FLAGS)
1594 		return flags;
1595 
1596 	/*
1597 	 * If the slab cache is for debugging (e.g. kmemleak) then
1598 	 * don't store user (stack trace) information by default,
1599 	 * but let the user enable it via the command line below.
1600 	 */
1601 	if (flags & SLAB_NOLEAKTRACE)
1602 		slub_debug_local &= ~SLAB_STORE_USER;
1603 
1604 	len = strlen(name);
1605 	next_block = slub_debug_string;
1606 	/* Go through all blocks of debug options, see if any matches our slab's name */
1607 	while (next_block) {
1608 		next_block = parse_slub_debug_flags(next_block, &block_flags, &iter, false);
1609 		if (!iter)
1610 			continue;
1611 		/* Found a block that has a slab list, search it */
1612 		while (*iter) {
1613 			char *end, *glob;
1614 			size_t cmplen;
1615 
1616 			end = strchrnul(iter, ',');
1617 			if (next_block && next_block < end)
1618 				end = next_block - 1;
1619 
1620 			glob = strnchr(iter, end - iter, '*');
1621 			if (glob)
1622 				cmplen = glob - iter;
1623 			else
1624 				cmplen = max_t(size_t, len, (end - iter));
1625 
1626 			if (!strncmp(name, iter, cmplen)) {
1627 				flags |= block_flags;
1628 				return flags;
1629 			}
1630 
1631 			if (!*end || *end == ';')
1632 				break;
1633 			iter = end + 1;
1634 		}
1635 	}
1636 
1637 	return flags | slub_debug_local;
1638 }
1639 #else /* !CONFIG_SLUB_DEBUG */
setup_object_debug(struct kmem_cache * s,void * object)1640 static inline void setup_object_debug(struct kmem_cache *s, void *object) {}
1641 static inline
setup_slab_debug(struct kmem_cache * s,struct slab * slab,void * addr)1642 void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr) {}
1643 
alloc_debug_processing(struct kmem_cache * s,struct slab * slab,void * object,int orig_size)1644 static inline int alloc_debug_processing(struct kmem_cache *s,
1645 	struct slab *slab, void *object, int orig_size) { return 0; }
1646 
free_debug_processing(struct kmem_cache * s,struct slab * slab,void * head,void * tail,int bulk_cnt,unsigned long addr)1647 static inline void free_debug_processing(
1648 	struct kmem_cache *s, struct slab *slab,
1649 	void *head, void *tail, int bulk_cnt,
1650 	unsigned long addr) {}
1651 
slab_pad_check(struct kmem_cache * s,struct slab * slab)1652 static inline void slab_pad_check(struct kmem_cache *s, struct slab *slab) {}
check_object(struct kmem_cache * s,struct slab * slab,void * object,u8 val)1653 static inline int check_object(struct kmem_cache *s, struct slab *slab,
1654 			void *object, u8 val) { return 1; }
set_track(struct kmem_cache * s,void * object,enum track_item alloc,unsigned long addr)1655 static inline void set_track(struct kmem_cache *s, void *object,
1656 			     enum track_item alloc, unsigned long addr) {}
add_full(struct kmem_cache * s,struct kmem_cache_node * n,struct slab * slab)1657 static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
1658 					struct slab *slab) {}
remove_full(struct kmem_cache * s,struct kmem_cache_node * n,struct slab * slab)1659 static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
1660 					struct slab *slab) {}
kmem_cache_flags(unsigned int object_size,slab_flags_t flags,const char * name)1661 slab_flags_t kmem_cache_flags(unsigned int object_size,
1662 	slab_flags_t flags, const char *name)
1663 {
1664 	return flags;
1665 }
1666 #define slub_debug 0
1667 
1668 #define disable_higher_order_debug 0
1669 
slabs_node(struct kmem_cache * s,int node)1670 static inline unsigned long slabs_node(struct kmem_cache *s, int node)
1671 							{ return 0; }
node_nr_slabs(struct kmem_cache_node * n)1672 static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
1673 							{ return 0; }
inc_slabs_node(struct kmem_cache * s,int node,int objects)1674 static inline void inc_slabs_node(struct kmem_cache *s, int node,
1675 							int objects) {}
dec_slabs_node(struct kmem_cache * s,int node,int objects)1676 static inline void dec_slabs_node(struct kmem_cache *s, int node,
1677 							int objects) {}
1678 
freelist_corrupted(struct kmem_cache * s,struct slab * slab,void ** freelist,void * nextfree)1679 static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
1680 			       void **freelist, void *nextfree)
1681 {
1682 	return false;
1683 }
1684 #endif /* CONFIG_SLUB_DEBUG */
1685 
1686 /*
1687  * Hooks for other subsystems that check memory allocations. In a typical
1688  * production configuration these hooks all should produce no code at all.
1689  */
slab_free_hook(struct kmem_cache * s,void * x,bool init)1690 static __always_inline bool slab_free_hook(struct kmem_cache *s,
1691 						void *x, bool init)
1692 {
1693 	kmemleak_free_recursive(x, s->flags);
1694 	kmsan_slab_free(s, x);
1695 
1696 	debug_check_no_locks_freed(x, s->object_size);
1697 
1698 	if (!(s->flags & SLAB_DEBUG_OBJECTS))
1699 		debug_check_no_obj_freed(x, s->object_size);
1700 
1701 	/* Use KCSAN to help debug racy use-after-free. */
1702 	if (!(s->flags & SLAB_TYPESAFE_BY_RCU))
1703 		__kcsan_check_access(x, s->object_size,
1704 				     KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);
1705 
1706 	/*
1707 	 * As memory initialization might be integrated into KASAN,
1708 	 * kasan_slab_free and initialization memset's must be
1709 	 * kept together to avoid discrepancies in behavior.
1710 	 *
1711 	 * The initialization memset's clear the object and the metadata,
1712 	 * but don't touch the SLAB redzone.
1713 	 */
1714 	if (init) {
1715 		int rsize;
1716 
1717 		if (!kasan_has_integrated_init())
1718 			memset(kasan_reset_tag(x), 0, s->object_size);
1719 		rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0;
1720 		memset((char *)kasan_reset_tag(x) + s->inuse, 0,
1721 		       s->size - s->inuse - rsize);
1722 	}
1723 	/* KASAN might put x into memory quarantine, delaying its reuse. */
1724 	return kasan_slab_free(s, x, init);
1725 }
1726 
slab_free_freelist_hook(struct kmem_cache * s,void ** head,void ** tail,int * cnt)1727 static inline bool slab_free_freelist_hook(struct kmem_cache *s,
1728 					   void **head, void **tail,
1729 					   int *cnt)
1730 {
1731 
1732 	void *object;
1733 	void *next = *head;
1734 	void *old_tail = *tail ? *tail : *head;
1735 
1736 	if (is_kfence_address(next)) {
1737 		slab_free_hook(s, next, false);
1738 		return true;
1739 	}
1740 
1741 	/* Head and tail of the reconstructed freelist */
1742 	*head = NULL;
1743 	*tail = NULL;
1744 
1745 	do {
1746 		object = next;
1747 		next = get_freepointer(s, object);
1748 
1749 		/* If object's reuse doesn't have to be delayed */
1750 		if (!slab_free_hook(s, object, slab_want_init_on_free(s))) {
1751 			/* Move object to the new freelist */
1752 			set_freepointer(s, object, *head);
1753 			*head = object;
1754 			if (!*tail)
1755 				*tail = object;
1756 		} else {
1757 			/*
1758 			 * Adjust the reconstructed freelist depth
1759 			 * accordingly if object's reuse is delayed.
1760 			 */
1761 			--(*cnt);
1762 		}
1763 	} while (object != old_tail);
1764 
1765 	if (*head == *tail)
1766 		*tail = NULL;
1767 
1768 	return *head != NULL;
1769 }
1770 
setup_object(struct kmem_cache * s,void * object)1771 static void *setup_object(struct kmem_cache *s, void *object)
1772 {
1773 	setup_object_debug(s, object);
1774 	object = kasan_init_slab_obj(s, object);
1775 	if (unlikely(s->ctor)) {
1776 		kasan_unpoison_object_data(s, object);
1777 		s->ctor(object);
1778 		kasan_poison_object_data(s, object);
1779 	}
1780 	return object;
1781 }
1782 
1783 /*
1784  * Slab allocation and freeing
1785  */
alloc_slab_page(gfp_t flags,int node,struct kmem_cache_order_objects oo)1786 static inline struct slab *alloc_slab_page(gfp_t flags, int node,
1787 		struct kmem_cache_order_objects oo)
1788 {
1789 	struct folio *folio;
1790 	struct slab *slab;
1791 	unsigned int order = oo_order(oo);
1792 
1793 	if (node == NUMA_NO_NODE)
1794 		folio = (struct folio *)alloc_pages(flags, order);
1795 	else
1796 		folio = (struct folio *)__alloc_pages_node(node, flags, order);
1797 
1798 	if (!folio)
1799 		return NULL;
1800 
1801 	slab = folio_slab(folio);
1802 	__folio_set_slab(folio);
1803 	if (page_is_pfmemalloc(folio_page(folio, 0)))
1804 		slab_set_pfmemalloc(slab);
1805 
1806 	return slab;
1807 }
1808 
1809 #ifdef CONFIG_SLAB_FREELIST_RANDOM
1810 /* Pre-initialize the random sequence cache */
init_cache_random_seq(struct kmem_cache * s)1811 static int init_cache_random_seq(struct kmem_cache *s)
1812 {
1813 	unsigned int count = oo_objects(s->oo);
1814 	int err;
1815 
1816 	/* Bailout if already initialised */
1817 	if (s->random_seq)
1818 		return 0;
1819 
1820 	err = cache_random_seq_create(s, count, GFP_KERNEL);
1821 	if (err) {
1822 		pr_err("SLUB: Unable to initialize free list for %s\n",
1823 			s->name);
1824 		return err;
1825 	}
1826 
1827 	/* Transform to an offset on the set of pages */
1828 	if (s->random_seq) {
1829 		unsigned int i;
1830 
1831 		for (i = 0; i < count; i++)
1832 			s->random_seq[i] *= s->size;
1833 	}
1834 	return 0;
1835 }
1836 
1837 /* Initialize each random sequence freelist per cache */
init_freelist_randomization(void)1838 static void __init init_freelist_randomization(void)
1839 {
1840 	struct kmem_cache *s;
1841 
1842 	mutex_lock(&slab_mutex);
1843 
1844 	list_for_each_entry(s, &slab_caches, list)
1845 		init_cache_random_seq(s);
1846 
1847 	mutex_unlock(&slab_mutex);
1848 }
1849 
1850 /* Get the next entry on the pre-computed freelist randomized */
next_freelist_entry(struct kmem_cache * s,struct slab * slab,unsigned long * pos,void * start,unsigned long page_limit,unsigned long freelist_count)1851 static void *next_freelist_entry(struct kmem_cache *s, struct slab *slab,
1852 				unsigned long *pos, void *start,
1853 				unsigned long page_limit,
1854 				unsigned long freelist_count)
1855 {
1856 	unsigned int idx;
1857 
1858 	/*
1859 	 * If the target page allocation failed, the number of objects on the
1860 	 * page might be smaller than the usual size defined by the cache.
1861 	 */
1862 	do {
1863 		idx = s->random_seq[*pos];
1864 		*pos += 1;
1865 		if (*pos >= freelist_count)
1866 			*pos = 0;
1867 	} while (unlikely(idx >= page_limit));
1868 
1869 	return (char *)start + idx;
1870 }
1871 
1872 /* Shuffle the single linked freelist based on a random pre-computed sequence */
shuffle_freelist(struct kmem_cache * s,struct slab * slab)1873 static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab)
1874 {
1875 	void *start;
1876 	void *cur;
1877 	void *next;
1878 	unsigned long idx, pos, page_limit, freelist_count;
1879 
1880 	if (slab->objects < 2 || !s->random_seq)
1881 		return false;
1882 
1883 	freelist_count = oo_objects(s->oo);
1884 	pos = prandom_u32_max(freelist_count);
1885 
1886 	page_limit = slab->objects * s->size;
1887 	start = fixup_red_left(s, slab_address(slab));
1888 
1889 	/* First entry is used as the base of the freelist */
1890 	cur = next_freelist_entry(s, slab, &pos, start, page_limit,
1891 				freelist_count);
1892 	cur = setup_object(s, cur);
1893 	slab->freelist = cur;
1894 
1895 	for (idx = 1; idx < slab->objects; idx++) {
1896 		next = next_freelist_entry(s, slab, &pos, start, page_limit,
1897 			freelist_count);
1898 		next = setup_object(s, next);
1899 		set_freepointer(s, cur, next);
1900 		cur = next;
1901 	}
1902 	set_freepointer(s, cur, NULL);
1903 
1904 	return true;
1905 }
1906 #else
init_cache_random_seq(struct kmem_cache * s)1907 static inline int init_cache_random_seq(struct kmem_cache *s)
1908 {
1909 	return 0;
1910 }
init_freelist_randomization(void)1911 static inline void init_freelist_randomization(void) { }
shuffle_freelist(struct kmem_cache * s,struct slab * slab)1912 static inline bool shuffle_freelist(struct kmem_cache *s, struct slab *slab)
1913 {
1914 	return false;
1915 }
1916 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1917 
allocate_slab(struct kmem_cache * s,gfp_t flags,int node)1918 static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
1919 {
1920 	struct slab *slab;
1921 	struct kmem_cache_order_objects oo = s->oo;
1922 	gfp_t alloc_gfp;
1923 	void *start, *p, *next;
1924 	int idx;
1925 	bool shuffle;
1926 
1927 	flags &= gfp_allowed_mask;
1928 
1929 	flags |= s->allocflags;
1930 
1931 	/*
1932 	 * Let the initial higher-order allocation fail under memory pressure
1933 	 * so we fall-back to the minimum order allocation.
1934 	 */
1935 	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
1936 	if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
1937 		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_RECLAIM;
1938 
1939 	slab = alloc_slab_page(alloc_gfp, node, oo);
1940 	if (unlikely(!slab)) {
1941 		oo = s->min;
1942 		alloc_gfp = flags;
1943 		/*
1944 		 * Allocation may have failed due to fragmentation.
1945 		 * Try a lower order alloc if possible
1946 		 */
1947 		slab = alloc_slab_page(alloc_gfp, node, oo);
1948 		if (unlikely(!slab))
1949 			return NULL;
1950 		stat(s, ORDER_FALLBACK);
1951 	}
1952 
1953 	slab->objects = oo_objects(oo);
1954 	slab->inuse = 0;
1955 	slab->frozen = 0;
1956 
1957 	account_slab(slab, oo_order(oo), s, flags);
1958 
1959 	slab->slab_cache = s;
1960 
1961 	kasan_poison_slab(slab);
1962 
1963 	start = slab_address(slab);
1964 
1965 	setup_slab_debug(s, slab, start);
1966 
1967 	shuffle = shuffle_freelist(s, slab);
1968 
1969 	if (!shuffle) {
1970 		start = fixup_red_left(s, start);
1971 		start = setup_object(s, start);
1972 		slab->freelist = start;
1973 		for (idx = 0, p = start; idx < slab->objects - 1; idx++) {
1974 			next = p + s->size;
1975 			next = setup_object(s, next);
1976 			set_freepointer(s, p, next);
1977 			p = next;
1978 		}
1979 		set_freepointer(s, p, NULL);
1980 	}
1981 
1982 	return slab;
1983 }
1984 
new_slab(struct kmem_cache * s,gfp_t flags,int node)1985 static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node)
1986 {
1987 	if (unlikely(flags & GFP_SLAB_BUG_MASK))
1988 		flags = kmalloc_fix_flags(flags);
1989 
1990 	WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO));
1991 
1992 	return allocate_slab(s,
1993 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
1994 }
1995 
__free_slab(struct kmem_cache * s,struct slab * slab)1996 static void __free_slab(struct kmem_cache *s, struct slab *slab)
1997 {
1998 	struct folio *folio = slab_folio(slab);
1999 	int order = folio_order(folio);
2000 	int pages = 1 << order;
2001 
2002 	if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
2003 		void *p;
2004 
2005 		slab_pad_check(s, slab);
2006 		for_each_object(p, s, slab_address(slab), slab->objects)
2007 			check_object(s, slab, p, SLUB_RED_INACTIVE);
2008 	}
2009 
2010 	__slab_clear_pfmemalloc(slab);
2011 	__folio_clear_slab(folio);
2012 	folio->mapping = NULL;
2013 	if (current->reclaim_state)
2014 		current->reclaim_state->reclaimed_slab += pages;
2015 	unaccount_slab(slab, order, s);
2016 	__free_pages(folio_page(folio, 0), order);
2017 }
2018 
rcu_free_slab(struct rcu_head * h)2019 static void rcu_free_slab(struct rcu_head *h)
2020 {
2021 	struct slab *slab = container_of(h, struct slab, rcu_head);
2022 
2023 	__free_slab(slab->slab_cache, slab);
2024 }
2025 
free_slab(struct kmem_cache * s,struct slab * slab)2026 static void free_slab(struct kmem_cache *s, struct slab *slab)
2027 {
2028 	if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
2029 		call_rcu(&slab->rcu_head, rcu_free_slab);
2030 	} else
2031 		__free_slab(s, slab);
2032 }
2033 
discard_slab(struct kmem_cache * s,struct slab * slab)2034 static void discard_slab(struct kmem_cache *s, struct slab *slab)
2035 {
2036 	dec_slabs_node(s, slab_nid(slab), slab->objects);
2037 	free_slab(s, slab);
2038 }
2039 
2040 /*
2041  * Management of partially allocated slabs.
2042  */
2043 static inline void
__add_partial(struct kmem_cache_node * n,struct slab * slab,int tail)2044 __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
2045 {
2046 	n->nr_partial++;
2047 	if (tail == DEACTIVATE_TO_TAIL)
2048 		list_add_tail(&slab->slab_list, &n->partial);
2049 	else
2050 		list_add(&slab->slab_list, &n->partial);
2051 }
2052 
add_partial(struct kmem_cache_node * n,struct slab * slab,int tail)2053 static inline void add_partial(struct kmem_cache_node *n,
2054 				struct slab *slab, int tail)
2055 {
2056 	lockdep_assert_held(&n->list_lock);
2057 	__add_partial(n, slab, tail);
2058 }
2059 
remove_partial(struct kmem_cache_node * n,struct slab * slab)2060 static inline void remove_partial(struct kmem_cache_node *n,
2061 					struct slab *slab)
2062 {
2063 	lockdep_assert_held(&n->list_lock);
2064 	list_del(&slab->slab_list);
2065 	n->nr_partial--;
2066 }
2067 
2068 /*
2069  * Called only for kmem_cache_debug() caches instead of acquire_slab(), with a
2070  * slab from the n->partial list. Remove only a single object from the slab, do
2071  * the alloc_debug_processing() checks and leave the slab on the list, or move
2072  * it to full list if it was the last free object.
2073  */
alloc_single_from_partial(struct kmem_cache * s,struct kmem_cache_node * n,struct slab * slab,int orig_size)2074 static void *alloc_single_from_partial(struct kmem_cache *s,
2075 		struct kmem_cache_node *n, struct slab *slab, int orig_size)
2076 {
2077 	void *object;
2078 
2079 	lockdep_assert_held(&n->list_lock);
2080 
2081 	object = slab->freelist;
2082 	slab->freelist = get_freepointer(s, object);
2083 	slab->inuse++;
2084 
2085 	if (!alloc_debug_processing(s, slab, object, orig_size)) {
2086 		remove_partial(n, slab);
2087 		return NULL;
2088 	}
2089 
2090 	if (slab->inuse == slab->objects) {
2091 		remove_partial(n, slab);
2092 		add_full(s, n, slab);
2093 	}
2094 
2095 	return object;
2096 }
2097 
2098 /*
2099  * Called only for kmem_cache_debug() caches to allocate from a freshly
2100  * allocated slab. Allocate a single object instead of whole freelist
2101  * and put the slab to the partial (or full) list.
2102  */
alloc_single_from_new_slab(struct kmem_cache * s,struct slab * slab,int orig_size)2103 static void *alloc_single_from_new_slab(struct kmem_cache *s,
2104 					struct slab *slab, int orig_size)
2105 {
2106 	int nid = slab_nid(slab);
2107 	struct kmem_cache_node *n = get_node(s, nid);
2108 	unsigned long flags;
2109 	void *object;
2110 
2111 
2112 	object = slab->freelist;
2113 	slab->freelist = get_freepointer(s, object);
2114 	slab->inuse = 1;
2115 
2116 	if (!alloc_debug_processing(s, slab, object, orig_size))
2117 		/*
2118 		 * It's not really expected that this would fail on a
2119 		 * freshly allocated slab, but a concurrent memory
2120 		 * corruption in theory could cause that.
2121 		 */
2122 		return NULL;
2123 
2124 	spin_lock_irqsave(&n->list_lock, flags);
2125 
2126 	if (slab->inuse == slab->objects)
2127 		add_full(s, n, slab);
2128 	else
2129 		add_partial(n, slab, DEACTIVATE_TO_HEAD);
2130 
2131 	inc_slabs_node(s, nid, slab->objects);
2132 	spin_unlock_irqrestore(&n->list_lock, flags);
2133 
2134 	return object;
2135 }
2136 
2137 /*
2138  * Remove slab from the partial list, freeze it and
2139  * return the pointer to the freelist.
2140  *
2141  * Returns a list of objects or NULL if it fails.
2142  */
acquire_slab(struct kmem_cache * s,struct kmem_cache_node * n,struct slab * slab,int mode)2143 static inline void *acquire_slab(struct kmem_cache *s,
2144 		struct kmem_cache_node *n, struct slab *slab,
2145 		int mode)
2146 {
2147 	void *freelist;
2148 	unsigned long counters;
2149 	struct slab new;
2150 
2151 	lockdep_assert_held(&n->list_lock);
2152 
2153 	/*
2154 	 * Zap the freelist and set the frozen bit.
2155 	 * The old freelist is the list of objects for the
2156 	 * per cpu allocation list.
2157 	 */
2158 	freelist = slab->freelist;
2159 	counters = slab->counters;
2160 	new.counters = counters;
2161 	if (mode) {
2162 		new.inuse = slab->objects;
2163 		new.freelist = NULL;
2164 	} else {
2165 		new.freelist = freelist;
2166 	}
2167 
2168 	VM_BUG_ON(new.frozen);
2169 	new.frozen = 1;
2170 
2171 	if (!__cmpxchg_double_slab(s, slab,
2172 			freelist, counters,
2173 			new.freelist, new.counters,
2174 			"acquire_slab"))
2175 		return NULL;
2176 
2177 	remove_partial(n, slab);
2178 	WARN_ON(!freelist);
2179 	return freelist;
2180 }
2181 
2182 #ifdef CONFIG_SLUB_CPU_PARTIAL
2183 static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain);
2184 #else
put_cpu_partial(struct kmem_cache * s,struct slab * slab,int drain)2185 static inline void put_cpu_partial(struct kmem_cache *s, struct slab *slab,
2186 				   int drain) { }
2187 #endif
2188 static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags);
2189 
2190 /*
2191  * Try to allocate a partial slab from a specific node.
2192  */
get_partial_node(struct kmem_cache * s,struct kmem_cache_node * n,struct partial_context * pc)2193 static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
2194 			      struct partial_context *pc)
2195 {
2196 	struct slab *slab, *slab2;
2197 	void *object = NULL;
2198 	unsigned long flags;
2199 	unsigned int partial_slabs = 0;
2200 
2201 	/*
2202 	 * Racy check. If we mistakenly see no partial slabs then we
2203 	 * just allocate an empty slab. If we mistakenly try to get a
2204 	 * partial slab and there is none available then get_partial()
2205 	 * will return NULL.
2206 	 */
2207 	if (!n || !n->nr_partial)
2208 		return NULL;
2209 
2210 	spin_lock_irqsave(&n->list_lock, flags);
2211 	list_for_each_entry_safe(slab, slab2, &n->partial, slab_list) {
2212 		void *t;
2213 
2214 		if (!pfmemalloc_match(slab, pc->flags))
2215 			continue;
2216 
2217 		if (kmem_cache_debug(s)) {
2218 			object = alloc_single_from_partial(s, n, slab,
2219 							pc->orig_size);
2220 			if (object)
2221 				break;
2222 			continue;
2223 		}
2224 
2225 		t = acquire_slab(s, n, slab, object == NULL);
2226 		if (!t)
2227 			break;
2228 
2229 		if (!object) {
2230 			*pc->slab = slab;
2231 			stat(s, ALLOC_FROM_PARTIAL);
2232 			object = t;
2233 		} else {
2234 			put_cpu_partial(s, slab, 0);
2235 			stat(s, CPU_PARTIAL_NODE);
2236 			partial_slabs++;
2237 		}
2238 #ifdef CONFIG_SLUB_CPU_PARTIAL
2239 		if (!kmem_cache_has_cpu_partial(s)
2240 			|| partial_slabs > s->cpu_partial_slabs / 2)
2241 			break;
2242 #else
2243 		break;
2244 #endif
2245 
2246 	}
2247 	spin_unlock_irqrestore(&n->list_lock, flags);
2248 	return object;
2249 }
2250 
2251 /*
2252  * Get a slab from somewhere. Search in increasing NUMA distances.
2253  */
get_any_partial(struct kmem_cache * s,struct partial_context * pc)2254 static void *get_any_partial(struct kmem_cache *s, struct partial_context *pc)
2255 {
2256 #ifdef CONFIG_NUMA
2257 	struct zonelist *zonelist;
2258 	struct zoneref *z;
2259 	struct zone *zone;
2260 	enum zone_type highest_zoneidx = gfp_zone(pc->flags);
2261 	void *object;
2262 	unsigned int cpuset_mems_cookie;
2263 
2264 	/*
2265 	 * The defrag ratio allows a configuration of the tradeoffs between
2266 	 * inter node defragmentation and node local allocations. A lower
2267 	 * defrag_ratio increases the tendency to do local allocations
2268 	 * instead of attempting to obtain partial slabs from other nodes.
2269 	 *
2270 	 * If the defrag_ratio is set to 0 then kmalloc() always
2271 	 * returns node local objects. If the ratio is higher then kmalloc()
2272 	 * may return off node objects because partial slabs are obtained
2273 	 * from other nodes and filled up.
2274 	 *
2275 	 * If /sys/kernel/slab/xx/remote_node_defrag_ratio is set to 100
2276 	 * (which makes defrag_ratio = 1000) then every (well almost)
2277 	 * allocation will first attempt to defrag slab caches on other nodes.
2278 	 * This means scanning over all nodes to look for partial slabs which
2279 	 * may be expensive if we do it every time we are trying to find a slab
2280 	 * with available objects.
2281 	 */
2282 	if (!s->remote_node_defrag_ratio ||
2283 			get_cycles() % 1024 > s->remote_node_defrag_ratio)
2284 		return NULL;
2285 
2286 	do {
2287 		cpuset_mems_cookie = read_mems_allowed_begin();
2288 		zonelist = node_zonelist(mempolicy_slab_node(), pc->flags);
2289 		for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) {
2290 			struct kmem_cache_node *n;
2291 
2292 			n = get_node(s, zone_to_nid(zone));
2293 
2294 			if (n && cpuset_zone_allowed(zone, pc->flags) &&
2295 					n->nr_partial > s->min_partial) {
2296 				object = get_partial_node(s, n, pc);
2297 				if (object) {
2298 					/*
2299 					 * Don't check read_mems_allowed_retry()
2300 					 * here - if mems_allowed was updated in
2301 					 * parallel, that was a harmless race
2302 					 * between allocation and the cpuset
2303 					 * update
2304 					 */
2305 					return object;
2306 				}
2307 			}
2308 		}
2309 	} while (read_mems_allowed_retry(cpuset_mems_cookie));
2310 #endif	/* CONFIG_NUMA */
2311 	return NULL;
2312 }
2313 
2314 /*
2315  * Get a partial slab, lock it and return it.
2316  */
get_partial(struct kmem_cache * s,int node,struct partial_context * pc)2317 static void *get_partial(struct kmem_cache *s, int node, struct partial_context *pc)
2318 {
2319 	void *object;
2320 	int searchnode = node;
2321 
2322 	if (node == NUMA_NO_NODE)
2323 		searchnode = numa_mem_id();
2324 
2325 	object = get_partial_node(s, get_node(s, searchnode), pc);
2326 	if (object || node != NUMA_NO_NODE)
2327 		return object;
2328 
2329 	return get_any_partial(s, pc);
2330 }
2331 
2332 #ifdef CONFIG_PREEMPTION
2333 /*
2334  * Calculate the next globally unique transaction for disambiguation
2335  * during cmpxchg. The transactions start with the cpu number and are then
2336  * incremented by CONFIG_NR_CPUS.
2337  */
2338 #define TID_STEP  roundup_pow_of_two(CONFIG_NR_CPUS)
2339 #else
2340 /*
2341  * No preemption supported therefore also no need to check for
2342  * different cpus.
2343  */
2344 #define TID_STEP 1
2345 #endif
2346 
next_tid(unsigned long tid)2347 static inline unsigned long next_tid(unsigned long tid)
2348 {
2349 	return tid + TID_STEP;
2350 }
2351 
2352 #ifdef SLUB_DEBUG_CMPXCHG
tid_to_cpu(unsigned long tid)2353 static inline unsigned int tid_to_cpu(unsigned long tid)
2354 {
2355 	return tid % TID_STEP;
2356 }
2357 
tid_to_event(unsigned long tid)2358 static inline unsigned long tid_to_event(unsigned long tid)
2359 {
2360 	return tid / TID_STEP;
2361 }
2362 #endif
2363 
init_tid(int cpu)2364 static inline unsigned int init_tid(int cpu)
2365 {
2366 	return cpu;
2367 }
2368 
note_cmpxchg_failure(const char * n,const struct kmem_cache * s,unsigned long tid)2369 static inline void note_cmpxchg_failure(const char *n,
2370 		const struct kmem_cache *s, unsigned long tid)
2371 {
2372 #ifdef SLUB_DEBUG_CMPXCHG
2373 	unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);
2374 
2375 	pr_info("%s %s: cmpxchg redo ", n, s->name);
2376 
2377 #ifdef CONFIG_PREEMPTION
2378 	if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
2379 		pr_warn("due to cpu change %d -> %d\n",
2380 			tid_to_cpu(tid), tid_to_cpu(actual_tid));
2381 	else
2382 #endif
2383 	if (tid_to_event(tid) != tid_to_event(actual_tid))
2384 		pr_warn("due to cpu running other code. Event %ld->%ld\n",
2385 			tid_to_event(tid), tid_to_event(actual_tid));
2386 	else
2387 		pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
2388 			actual_tid, tid, next_tid(tid));
2389 #endif
2390 	stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
2391 }
2392 
init_kmem_cache_cpus(struct kmem_cache * s)2393 static void init_kmem_cache_cpus(struct kmem_cache *s)
2394 {
2395 	int cpu;
2396 	struct kmem_cache_cpu *c;
2397 
2398 	for_each_possible_cpu(cpu) {
2399 		c = per_cpu_ptr(s->cpu_slab, cpu);
2400 		local_lock_init(&c->lock);
2401 		c->tid = init_tid(cpu);
2402 	}
2403 }
2404 
2405 /*
2406  * Finishes removing the cpu slab. Merges cpu's freelist with slab's freelist,
2407  * unfreezes the slabs and puts it on the proper list.
2408  * Assumes the slab has been already safely taken away from kmem_cache_cpu
2409  * by the caller.
2410  */
deactivate_slab(struct kmem_cache * s,struct slab * slab,void * freelist)2411 static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
2412 			    void *freelist)
2413 {
2414 	enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE, M_FULL_NOLIST };
2415 	struct kmem_cache_node *n = get_node(s, slab_nid(slab));
2416 	int free_delta = 0;
2417 	enum slab_modes mode = M_NONE;
2418 	void *nextfree, *freelist_iter, *freelist_tail;
2419 	int tail = DEACTIVATE_TO_HEAD;
2420 	unsigned long flags = 0;
2421 	struct slab new;
2422 	struct slab old;
2423 
2424 	if (slab->freelist) {
2425 		stat(s, DEACTIVATE_REMOTE_FREES);
2426 		tail = DEACTIVATE_TO_TAIL;
2427 	}
2428 
2429 	/*
2430 	 * Stage one: Count the objects on cpu's freelist as free_delta and
2431 	 * remember the last object in freelist_tail for later splicing.
2432 	 */
2433 	freelist_tail = NULL;
2434 	freelist_iter = freelist;
2435 	while (freelist_iter) {
2436 		nextfree = get_freepointer(s, freelist_iter);
2437 
2438 		/*
2439 		 * If 'nextfree' is invalid, it is possible that the object at
2440 		 * 'freelist_iter' is already corrupted.  So isolate all objects
2441 		 * starting at 'freelist_iter' by skipping them.
2442 		 */
2443 		if (freelist_corrupted(s, slab, &freelist_iter, nextfree))
2444 			break;
2445 
2446 		freelist_tail = freelist_iter;
2447 		free_delta++;
2448 
2449 		freelist_iter = nextfree;
2450 	}
2451 
2452 	/*
2453 	 * Stage two: Unfreeze the slab while splicing the per-cpu
2454 	 * freelist to the head of slab's freelist.
2455 	 *
2456 	 * Ensure that the slab is unfrozen while the list presence
2457 	 * reflects the actual number of objects during unfreeze.
2458 	 *
2459 	 * We first perform cmpxchg holding lock and insert to list
2460 	 * when it succeed. If there is mismatch then the slab is not
2461 	 * unfrozen and number of objects in the slab may have changed.
2462 	 * Then release lock and retry cmpxchg again.
2463 	 */
2464 redo:
2465 
2466 	old.freelist = READ_ONCE(slab->freelist);
2467 	old.counters = READ_ONCE(slab->counters);
2468 	VM_BUG_ON(!old.frozen);
2469 
2470 	/* Determine target state of the slab */
2471 	new.counters = old.counters;
2472 	if (freelist_tail) {
2473 		new.inuse -= free_delta;
2474 		set_freepointer(s, freelist_tail, old.freelist);
2475 		new.freelist = freelist;
2476 	} else
2477 		new.freelist = old.freelist;
2478 
2479 	new.frozen = 0;
2480 
2481 	if (!new.inuse && n->nr_partial >= s->min_partial) {
2482 		mode = M_FREE;
2483 	} else if (new.freelist) {
2484 		mode = M_PARTIAL;
2485 		/*
2486 		 * Taking the spinlock removes the possibility that
2487 		 * acquire_slab() will see a slab that is frozen
2488 		 */
2489 		spin_lock_irqsave(&n->list_lock, flags);
2490 	} else if (kmem_cache_debug_flags(s, SLAB_STORE_USER)) {
2491 		mode = M_FULL;
2492 		/*
2493 		 * This also ensures that the scanning of full
2494 		 * slabs from diagnostic functions will not see
2495 		 * any frozen slabs.
2496 		 */
2497 		spin_lock_irqsave(&n->list_lock, flags);
2498 	} else {
2499 		mode = M_FULL_NOLIST;
2500 	}
2501 
2502 
2503 	if (!cmpxchg_double_slab(s, slab,
2504 				old.freelist, old.counters,
2505 				new.freelist, new.counters,
2506 				"unfreezing slab")) {
2507 		if (mode == M_PARTIAL || mode == M_FULL)
2508 			spin_unlock_irqrestore(&n->list_lock, flags);
2509 		goto redo;
2510 	}
2511 
2512 
2513 	if (mode == M_PARTIAL) {
2514 		add_partial(n, slab, tail);
2515 		spin_unlock_irqrestore(&n->list_lock, flags);
2516 		stat(s, tail);
2517 	} else if (mode == M_FREE) {
2518 		stat(s, DEACTIVATE_EMPTY);
2519 		discard_slab(s, slab);
2520 		stat(s, FREE_SLAB);
2521 	} else if (mode == M_FULL) {
2522 		add_full(s, n, slab);
2523 		spin_unlock_irqrestore(&n->list_lock, flags);
2524 		stat(s, DEACTIVATE_FULL);
2525 	} else if (mode == M_FULL_NOLIST) {
2526 		stat(s, DEACTIVATE_FULL);
2527 	}
2528 }
2529 
2530 #ifdef CONFIG_SLUB_CPU_PARTIAL
__unfreeze_partials(struct kmem_cache * s,struct slab * partial_slab)2531 static void __unfreeze_partials(struct kmem_cache *s, struct slab *partial_slab)
2532 {
2533 	struct kmem_cache_node *n = NULL, *n2 = NULL;
2534 	struct slab *slab, *slab_to_discard = NULL;
2535 	unsigned long flags = 0;
2536 
2537 	while (partial_slab) {
2538 		struct slab new;
2539 		struct slab old;
2540 
2541 		slab = partial_slab;
2542 		partial_slab = slab->next;
2543 
2544 		n2 = get_node(s, slab_nid(slab));
2545 		if (n != n2) {
2546 			if (n)
2547 				spin_unlock_irqrestore(&n->list_lock, flags);
2548 
2549 			n = n2;
2550 			spin_lock_irqsave(&n->list_lock, flags);
2551 		}
2552 
2553 		do {
2554 
2555 			old.freelist = slab->freelist;
2556 			old.counters = slab->counters;
2557 			VM_BUG_ON(!old.frozen);
2558 
2559 			new.counters = old.counters;
2560 			new.freelist = old.freelist;
2561 
2562 			new.frozen = 0;
2563 
2564 		} while (!__cmpxchg_double_slab(s, slab,
2565 				old.freelist, old.counters,
2566 				new.freelist, new.counters,
2567 				"unfreezing slab"));
2568 
2569 		if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
2570 			slab->next = slab_to_discard;
2571 			slab_to_discard = slab;
2572 		} else {
2573 			add_partial(n, slab, DEACTIVATE_TO_TAIL);
2574 			stat(s, FREE_ADD_PARTIAL);
2575 		}
2576 	}
2577 
2578 	if (n)
2579 		spin_unlock_irqrestore(&n->list_lock, flags);
2580 
2581 	while (slab_to_discard) {
2582 		slab = slab_to_discard;
2583 		slab_to_discard = slab_to_discard->next;
2584 
2585 		stat(s, DEACTIVATE_EMPTY);
2586 		discard_slab(s, slab);
2587 		stat(s, FREE_SLAB);
2588 	}
2589 }
2590 
2591 /*
2592  * Unfreeze all the cpu partial slabs.
2593  */
unfreeze_partials(struct kmem_cache * s)2594 static void unfreeze_partials(struct kmem_cache *s)
2595 {
2596 	struct slab *partial_slab;
2597 	unsigned long flags;
2598 
2599 	local_lock_irqsave(&s->cpu_slab->lock, flags);
2600 	partial_slab = this_cpu_read(s->cpu_slab->partial);
2601 	this_cpu_write(s->cpu_slab->partial, NULL);
2602 	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
2603 
2604 	if (partial_slab)
2605 		__unfreeze_partials(s, partial_slab);
2606 }
2607 
unfreeze_partials_cpu(struct kmem_cache * s,struct kmem_cache_cpu * c)2608 static void unfreeze_partials_cpu(struct kmem_cache *s,
2609 				  struct kmem_cache_cpu *c)
2610 {
2611 	struct slab *partial_slab;
2612 
2613 	partial_slab = slub_percpu_partial(c);
2614 	c->partial = NULL;
2615 
2616 	if (partial_slab)
2617 		__unfreeze_partials(s, partial_slab);
2618 }
2619 
2620 /*
2621  * Put a slab that was just frozen (in __slab_free|get_partial_node) into a
2622  * partial slab slot if available.
2623  *
2624  * If we did not find a slot then simply move all the partials to the
2625  * per node partial list.
2626  */
put_cpu_partial(struct kmem_cache * s,struct slab * slab,int drain)2627 static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain)
2628 {
2629 	struct slab *oldslab;
2630 	struct slab *slab_to_unfreeze = NULL;
2631 	unsigned long flags;
2632 	int slabs = 0;
2633 
2634 	local_lock_irqsave(&s->cpu_slab->lock, flags);
2635 
2636 	oldslab = this_cpu_read(s->cpu_slab->partial);
2637 
2638 	if (oldslab) {
2639 		if (drain && oldslab->slabs >= s->cpu_partial_slabs) {
2640 			/*
2641 			 * Partial array is full. Move the existing set to the
2642 			 * per node partial list. Postpone the actual unfreezing
2643 			 * outside of the critical section.
2644 			 */
2645 			slab_to_unfreeze = oldslab;
2646 			oldslab = NULL;
2647 		} else {
2648 			slabs = oldslab->slabs;
2649 		}
2650 	}
2651 
2652 	slabs++;
2653 
2654 	slab->slabs = slabs;
2655 	slab->next = oldslab;
2656 
2657 	this_cpu_write(s->cpu_slab->partial, slab);
2658 
2659 	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
2660 
2661 	if (slab_to_unfreeze) {
2662 		__unfreeze_partials(s, slab_to_unfreeze);
2663 		stat(s, CPU_PARTIAL_DRAIN);
2664 	}
2665 }
2666 
2667 #else	/* CONFIG_SLUB_CPU_PARTIAL */
2668 
unfreeze_partials(struct kmem_cache * s)2669 static inline void unfreeze_partials(struct kmem_cache *s) { }
unfreeze_partials_cpu(struct kmem_cache * s,struct kmem_cache_cpu * c)2670 static inline void unfreeze_partials_cpu(struct kmem_cache *s,
2671 				  struct kmem_cache_cpu *c) { }
2672 
2673 #endif	/* CONFIG_SLUB_CPU_PARTIAL */
2674 
flush_slab(struct kmem_cache * s,struct kmem_cache_cpu * c)2675 static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
2676 {
2677 	unsigned long flags;
2678 	struct slab *slab;
2679 	void *freelist;
2680 
2681 	local_lock_irqsave(&s->cpu_slab->lock, flags);
2682 
2683 	slab = c->slab;
2684 	freelist = c->freelist;
2685 
2686 	c->slab = NULL;
2687 	c->freelist = NULL;
2688 	c->tid = next_tid(c->tid);
2689 
2690 	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
2691 
2692 	if (slab) {
2693 		deactivate_slab(s, slab, freelist);
2694 		stat(s, CPUSLAB_FLUSH);
2695 	}
2696 }
2697 
__flush_cpu_slab(struct kmem_cache * s,int cpu)2698 static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
2699 {
2700 	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
2701 	void *freelist = c->freelist;
2702 	struct slab *slab = c->slab;
2703 
2704 	c->slab = NULL;
2705 	c->freelist = NULL;
2706 	c->tid = next_tid(c->tid);
2707 
2708 	if (slab) {
2709 		deactivate_slab(s, slab, freelist);
2710 		stat(s, CPUSLAB_FLUSH);
2711 	}
2712 
2713 	unfreeze_partials_cpu(s, c);
2714 }
2715 
2716 struct slub_flush_work {
2717 	struct work_struct work;
2718 	struct kmem_cache *s;
2719 	bool skip;
2720 };
2721 
2722 /*
2723  * Flush cpu slab.
2724  *
2725  * Called from CPU work handler with migration disabled.
2726  */
flush_cpu_slab(struct work_struct * w)2727 static void flush_cpu_slab(struct work_struct *w)
2728 {
2729 	struct kmem_cache *s;
2730 	struct kmem_cache_cpu *c;
2731 	struct slub_flush_work *sfw;
2732 
2733 	sfw = container_of(w, struct slub_flush_work, work);
2734 
2735 	s = sfw->s;
2736 	c = this_cpu_ptr(s->cpu_slab);
2737 
2738 	if (c->slab)
2739 		flush_slab(s, c);
2740 
2741 	unfreeze_partials(s);
2742 }
2743 
has_cpu_slab(int cpu,struct kmem_cache * s)2744 static bool has_cpu_slab(int cpu, struct kmem_cache *s)
2745 {
2746 	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
2747 
2748 	return c->slab || slub_percpu_partial(c);
2749 }
2750 
2751 static DEFINE_MUTEX(flush_lock);
2752 static DEFINE_PER_CPU(struct slub_flush_work, slub_flush);
2753 
flush_all_cpus_locked(struct kmem_cache * s)2754 static void flush_all_cpus_locked(struct kmem_cache *s)
2755 {
2756 	struct slub_flush_work *sfw;
2757 	unsigned int cpu;
2758 
2759 	lockdep_assert_cpus_held();
2760 	mutex_lock(&flush_lock);
2761 
2762 	for_each_online_cpu(cpu) {
2763 		sfw = &per_cpu(slub_flush, cpu);
2764 		if (!has_cpu_slab(cpu, s)) {
2765 			sfw->skip = true;
2766 			continue;
2767 		}
2768 		INIT_WORK(&sfw->work, flush_cpu_slab);
2769 		sfw->skip = false;
2770 		sfw->s = s;
2771 		queue_work_on(cpu, flushwq, &sfw->work);
2772 	}
2773 
2774 	for_each_online_cpu(cpu) {
2775 		sfw = &per_cpu(slub_flush, cpu);
2776 		if (sfw->skip)
2777 			continue;
2778 		flush_work(&sfw->work);
2779 	}
2780 
2781 	mutex_unlock(&flush_lock);
2782 }
2783 
flush_all(struct kmem_cache * s)2784 static void flush_all(struct kmem_cache *s)
2785 {
2786 	cpus_read_lock();
2787 	flush_all_cpus_locked(s);
2788 	cpus_read_unlock();
2789 }
2790 
2791 /*
2792  * Use the cpu notifier to insure that the cpu slabs are flushed when
2793  * necessary.
2794  */
slub_cpu_dead(unsigned int cpu)2795 static int slub_cpu_dead(unsigned int cpu)
2796 {
2797 	struct kmem_cache *s;
2798 
2799 	mutex_lock(&slab_mutex);
2800 	list_for_each_entry(s, &slab_caches, list)
2801 		__flush_cpu_slab(s, cpu);
2802 	mutex_unlock(&slab_mutex);
2803 	return 0;
2804 }
2805 
2806 /*
2807  * Check if the objects in a per cpu structure fit numa
2808  * locality expectations.
2809  */
node_match(struct slab * slab,int node)2810 static inline int node_match(struct slab *slab, int node)
2811 {
2812 #ifdef CONFIG_NUMA
2813 	if (node != NUMA_NO_NODE && slab_nid(slab) != node)
2814 		return 0;
2815 #endif
2816 	return 1;
2817 }
2818 
2819 #ifdef CONFIG_SLUB_DEBUG
count_free(struct slab * slab)2820 static int count_free(struct slab *slab)
2821 {
2822 	return slab->objects - slab->inuse;
2823 }
2824 
node_nr_objs(struct kmem_cache_node * n)2825 static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
2826 {
2827 	return atomic_long_read(&n->total_objects);
2828 }
2829 
2830 /* Supports checking bulk free of a constructed freelist */
free_debug_processing(struct kmem_cache * s,struct slab * slab,void * head,void * tail,int bulk_cnt,unsigned long addr)2831 static noinline void free_debug_processing(
2832 	struct kmem_cache *s, struct slab *slab,
2833 	void *head, void *tail, int bulk_cnt,
2834 	unsigned long addr)
2835 {
2836 	struct kmem_cache_node *n = get_node(s, slab_nid(slab));
2837 	struct slab *slab_free = NULL;
2838 	void *object = head;
2839 	int cnt = 0;
2840 	unsigned long flags;
2841 	bool checks_ok = false;
2842 	depot_stack_handle_t handle = 0;
2843 
2844 	if (s->flags & SLAB_STORE_USER)
2845 		handle = set_track_prepare();
2846 
2847 	spin_lock_irqsave(&n->list_lock, flags);
2848 
2849 	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
2850 		if (!check_slab(s, slab))
2851 			goto out;
2852 	}
2853 
2854 	if (slab->inuse < bulk_cnt) {
2855 		slab_err(s, slab, "Slab has %d allocated objects but %d are to be freed\n",
2856 			 slab->inuse, bulk_cnt);
2857 		goto out;
2858 	}
2859 
2860 next_object:
2861 
2862 	if (++cnt > bulk_cnt)
2863 		goto out_cnt;
2864 
2865 	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
2866 		if (!free_consistency_checks(s, slab, object, addr))
2867 			goto out;
2868 	}
2869 
2870 	if (s->flags & SLAB_STORE_USER)
2871 		set_track_update(s, object, TRACK_FREE, addr, handle);
2872 	trace(s, slab, object, 0);
2873 	/* Freepointer not overwritten by init_object(), SLAB_POISON moved it */
2874 	init_object(s, object, SLUB_RED_INACTIVE);
2875 
2876 	/* Reached end of constructed freelist yet? */
2877 	if (object != tail) {
2878 		object = get_freepointer(s, object);
2879 		goto next_object;
2880 	}
2881 	checks_ok = true;
2882 
2883 out_cnt:
2884 	if (cnt != bulk_cnt)
2885 		slab_err(s, slab, "Bulk free expected %d objects but found %d\n",
2886 			 bulk_cnt, cnt);
2887 
2888 out:
2889 	if (checks_ok) {
2890 		void *prior = slab->freelist;
2891 
2892 		/* Perform the actual freeing while we still hold the locks */
2893 		slab->inuse -= cnt;
2894 		set_freepointer(s, tail, prior);
2895 		slab->freelist = head;
2896 
2897 		/*
2898 		 * If the slab is empty, and node's partial list is full,
2899 		 * it should be discarded anyway no matter it's on full or
2900 		 * partial list.
2901 		 */
2902 		if (slab->inuse == 0 && n->nr_partial >= s->min_partial)
2903 			slab_free = slab;
2904 
2905 		if (!prior) {
2906 			/* was on full list */
2907 			remove_full(s, n, slab);
2908 			if (!slab_free) {
2909 				add_partial(n, slab, DEACTIVATE_TO_TAIL);
2910 				stat(s, FREE_ADD_PARTIAL);
2911 			}
2912 		} else if (slab_free) {
2913 			remove_partial(n, slab);
2914 			stat(s, FREE_REMOVE_PARTIAL);
2915 		}
2916 	}
2917 
2918 	if (slab_free) {
2919 		/*
2920 		 * Update the counters while still holding n->list_lock to
2921 		 * prevent spurious validation warnings
2922 		 */
2923 		dec_slabs_node(s, slab_nid(slab_free), slab_free->objects);
2924 	}
2925 
2926 	spin_unlock_irqrestore(&n->list_lock, flags);
2927 
2928 	if (!checks_ok)
2929 		slab_fix(s, "Object at 0x%p not freed", object);
2930 
2931 	if (slab_free) {
2932 		stat(s, FREE_SLAB);
2933 		free_slab(s, slab_free);
2934 	}
2935 }
2936 #endif /* CONFIG_SLUB_DEBUG */
2937 
2938 #if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
count_partial(struct kmem_cache_node * n,int (* get_count)(struct slab *))2939 static unsigned long count_partial(struct kmem_cache_node *n,
2940 					int (*get_count)(struct slab *))
2941 {
2942 	unsigned long flags;
2943 	unsigned long x = 0;
2944 	struct slab *slab;
2945 
2946 	spin_lock_irqsave(&n->list_lock, flags);
2947 	list_for_each_entry(slab, &n->partial, slab_list)
2948 		x += get_count(slab);
2949 	spin_unlock_irqrestore(&n->list_lock, flags);
2950 	return x;
2951 }
2952 #endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */
2953 
2954 static noinline void
slab_out_of_memory(struct kmem_cache * s,gfp_t gfpflags,int nid)2955 slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
2956 {
2957 #ifdef CONFIG_SLUB_DEBUG
2958 	static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
2959 				      DEFAULT_RATELIMIT_BURST);
2960 	int node;
2961 	struct kmem_cache_node *n;
2962 
2963 	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
2964 		return;
2965 
2966 	pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
2967 		nid, gfpflags, &gfpflags);
2968 	pr_warn("  cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n",
2969 		s->name, s->object_size, s->size, oo_order(s->oo),
2970 		oo_order(s->min));
2971 
2972 	if (oo_order(s->min) > get_order(s->object_size))
2973 		pr_warn("  %s debugging increased min order, use slub_debug=O to disable.\n",
2974 			s->name);
2975 
2976 	for_each_kmem_cache_node(s, node, n) {
2977 		unsigned long nr_slabs;
2978 		unsigned long nr_objs;
2979 		unsigned long nr_free;
2980 
2981 		nr_free  = count_partial(n, count_free);
2982 		nr_slabs = node_nr_slabs(n);
2983 		nr_objs  = node_nr_objs(n);
2984 
2985 		pr_warn("  node %d: slabs: %ld, objs: %ld, free: %ld\n",
2986 			node, nr_slabs, nr_objs, nr_free);
2987 	}
2988 #endif
2989 }
2990 
pfmemalloc_match(struct slab * slab,gfp_t gfpflags)2991 static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags)
2992 {
2993 	if (unlikely(slab_test_pfmemalloc(slab)))
2994 		return gfp_pfmemalloc_allowed(gfpflags);
2995 
2996 	return true;
2997 }
2998 
2999 /*
3000  * Check the slab->freelist and either transfer the freelist to the
3001  * per cpu freelist or deactivate the slab.
3002  *
3003  * The slab is still frozen if the return value is not NULL.
3004  *
3005  * If this function returns NULL then the slab has been unfrozen.
3006  */
get_freelist(struct kmem_cache * s,struct slab * slab)3007 static inline void *get_freelist(struct kmem_cache *s, struct slab *slab)
3008 {
3009 	struct slab new;
3010 	unsigned long counters;
3011 	void *freelist;
3012 
3013 	lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
3014 
3015 	do {
3016 		freelist = slab->freelist;
3017 		counters = slab->counters;
3018 
3019 		new.counters = counters;
3020 		VM_BUG_ON(!new.frozen);
3021 
3022 		new.inuse = slab->objects;
3023 		new.frozen = freelist != NULL;
3024 
3025 	} while (!__cmpxchg_double_slab(s, slab,
3026 		freelist, counters,
3027 		NULL, new.counters,
3028 		"get_freelist"));
3029 
3030 	return freelist;
3031 }
3032 
3033 /*
3034  * Slow path. The lockless freelist is empty or we need to perform
3035  * debugging duties.
3036  *
3037  * Processing is still very fast if new objects have been freed to the
3038  * regular freelist. In that case we simply take over the regular freelist
3039  * as the lockless freelist and zap the regular freelist.
3040  *
3041  * If that is not working then we fall back to the partial lists. We take the
3042  * first element of the freelist as the object to allocate now and move the
3043  * rest of the freelist to the lockless freelist.
3044  *
3045  * And if we were unable to get a new slab from the partial slab lists then
3046  * we need to allocate a new slab. This is the slowest path since it involves
3047  * a call to the page allocator and the setup of a new slab.
3048  *
3049  * Version of __slab_alloc to use when we know that preemption is
3050  * already disabled (which is the case for bulk allocation).
3051  */
___slab_alloc(struct kmem_cache * s,gfp_t gfpflags,int node,unsigned long addr,struct kmem_cache_cpu * c,unsigned int orig_size)3052 static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
3053 			  unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
3054 {
3055 	void *freelist;
3056 	struct slab *slab;
3057 	unsigned long flags;
3058 	struct partial_context pc;
3059 
3060 	stat(s, ALLOC_SLOWPATH);
3061 
3062 reread_slab:
3063 
3064 	slab = READ_ONCE(c->slab);
3065 	if (!slab) {
3066 		/*
3067 		 * if the node is not online or has no normal memory, just
3068 		 * ignore the node constraint
3069 		 */
3070 		if (unlikely(node != NUMA_NO_NODE &&
3071 			     !node_isset(node, slab_nodes)))
3072 			node = NUMA_NO_NODE;
3073 		goto new_slab;
3074 	}
3075 redo:
3076 
3077 	if (unlikely(!node_match(slab, node))) {
3078 		/*
3079 		 * same as above but node_match() being false already
3080 		 * implies node != NUMA_NO_NODE
3081 		 */
3082 		if (!node_isset(node, slab_nodes)) {
3083 			node = NUMA_NO_NODE;
3084 		} else {
3085 			stat(s, ALLOC_NODE_MISMATCH);
3086 			goto deactivate_slab;
3087 		}
3088 	}
3089 
3090 	/*
3091 	 * By rights, we should be searching for a slab page that was
3092 	 * PFMEMALLOC but right now, we are losing the pfmemalloc
3093 	 * information when the page leaves the per-cpu allocator
3094 	 */
3095 	if (unlikely(!pfmemalloc_match(slab, gfpflags)))
3096 		goto deactivate_slab;
3097 
3098 	/* must check again c->slab in case we got preempted and it changed */
3099 	local_lock_irqsave(&s->cpu_slab->lock, flags);
3100 	if (unlikely(slab != c->slab)) {
3101 		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3102 		goto reread_slab;
3103 	}
3104 	freelist = c->freelist;
3105 	if (freelist)
3106 		goto load_freelist;
3107 
3108 	freelist = get_freelist(s, slab);
3109 
3110 	if (!freelist) {
3111 		c->slab = NULL;
3112 		c->tid = next_tid(c->tid);
3113 		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3114 		stat(s, DEACTIVATE_BYPASS);
3115 		goto new_slab;
3116 	}
3117 
3118 	stat(s, ALLOC_REFILL);
3119 
3120 load_freelist:
3121 
3122 	lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
3123 
3124 	/*
3125 	 * freelist is pointing to the list of objects to be used.
3126 	 * slab is pointing to the slab from which the objects are obtained.
3127 	 * That slab must be frozen for per cpu allocations to work.
3128 	 */
3129 	VM_BUG_ON(!c->slab->frozen);
3130 	c->freelist = get_freepointer(s, freelist);
3131 	c->tid = next_tid(c->tid);
3132 	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3133 	return freelist;
3134 
3135 deactivate_slab:
3136 
3137 	local_lock_irqsave(&s->cpu_slab->lock, flags);
3138 	if (slab != c->slab) {
3139 		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3140 		goto reread_slab;
3141 	}
3142 	freelist = c->freelist;
3143 	c->slab = NULL;
3144 	c->freelist = NULL;
3145 	c->tid = next_tid(c->tid);
3146 	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3147 	deactivate_slab(s, slab, freelist);
3148 
3149 new_slab:
3150 
3151 	if (slub_percpu_partial(c)) {
3152 		local_lock_irqsave(&s->cpu_slab->lock, flags);
3153 		if (unlikely(c->slab)) {
3154 			local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3155 			goto reread_slab;
3156 		}
3157 		if (unlikely(!slub_percpu_partial(c))) {
3158 			local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3159 			/* we were preempted and partial list got empty */
3160 			goto new_objects;
3161 		}
3162 
3163 		slab = c->slab = slub_percpu_partial(c);
3164 		slub_set_percpu_partial(c, slab);
3165 		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3166 		stat(s, CPU_PARTIAL_ALLOC);
3167 		goto redo;
3168 	}
3169 
3170 new_objects:
3171 
3172 	pc.flags = gfpflags;
3173 	pc.slab = &slab;
3174 	pc.orig_size = orig_size;
3175 	freelist = get_partial(s, node, &pc);
3176 	if (freelist)
3177 		goto check_new_slab;
3178 
3179 	slub_put_cpu_ptr(s->cpu_slab);
3180 	slab = new_slab(s, gfpflags, node);
3181 	c = slub_get_cpu_ptr(s->cpu_slab);
3182 
3183 	if (unlikely(!slab)) {
3184 		slab_out_of_memory(s, gfpflags, node);
3185 		return NULL;
3186 	}
3187 
3188 	stat(s, ALLOC_SLAB);
3189 
3190 	if (kmem_cache_debug(s)) {
3191 		freelist = alloc_single_from_new_slab(s, slab, orig_size);
3192 
3193 		if (unlikely(!freelist))
3194 			goto new_objects;
3195 
3196 		if (s->flags & SLAB_STORE_USER)
3197 			set_track(s, freelist, TRACK_ALLOC, addr);
3198 
3199 		return freelist;
3200 	}
3201 
3202 	/*
3203 	 * No other reference to the slab yet so we can
3204 	 * muck around with it freely without cmpxchg
3205 	 */
3206 	freelist = slab->freelist;
3207 	slab->freelist = NULL;
3208 	slab->inuse = slab->objects;
3209 	slab->frozen = 1;
3210 
3211 	inc_slabs_node(s, slab_nid(slab), slab->objects);
3212 
3213 check_new_slab:
3214 
3215 	if (kmem_cache_debug(s)) {
3216 		/*
3217 		 * For debug caches here we had to go through
3218 		 * alloc_single_from_partial() so just store the tracking info
3219 		 * and return the object
3220 		 */
3221 		if (s->flags & SLAB_STORE_USER)
3222 			set_track(s, freelist, TRACK_ALLOC, addr);
3223 
3224 		return freelist;
3225 	}
3226 
3227 	if (unlikely(!pfmemalloc_match(slab, gfpflags))) {
3228 		/*
3229 		 * For !pfmemalloc_match() case we don't load freelist so that
3230 		 * we don't make further mismatched allocations easier.
3231 		 */
3232 		deactivate_slab(s, slab, get_freepointer(s, freelist));
3233 		return freelist;
3234 	}
3235 
3236 retry_load_slab:
3237 
3238 	local_lock_irqsave(&s->cpu_slab->lock, flags);
3239 	if (unlikely(c->slab)) {
3240 		void *flush_freelist = c->freelist;
3241 		struct slab *flush_slab = c->slab;
3242 
3243 		c->slab = NULL;
3244 		c->freelist = NULL;
3245 		c->tid = next_tid(c->tid);
3246 
3247 		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
3248 
3249 		deactivate_slab(s, flush_slab, flush_freelist);
3250 
3251 		stat(s, CPUSLAB_FLUSH);
3252 
3253 		goto retry_load_slab;
3254 	}
3255 	c->slab = slab;
3256 
3257 	goto load_freelist;
3258 }
3259 
3260 /*
3261  * A wrapper for ___slab_alloc() for contexts where preemption is not yet
3262  * disabled. Compensates for possible cpu changes by refetching the per cpu area
3263  * pointer.
3264  */
__slab_alloc(struct kmem_cache * s,gfp_t gfpflags,int node,unsigned long addr,struct kmem_cache_cpu * c,unsigned int orig_size)3265 static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
3266 			  unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
3267 {
3268 	void *p;
3269 
3270 #ifdef CONFIG_PREEMPT_COUNT
3271 	/*
3272 	 * We may have been preempted and rescheduled on a different
3273 	 * cpu before disabling preemption. Need to reload cpu area
3274 	 * pointer.
3275 	 */
3276 	c = slub_get_cpu_ptr(s->cpu_slab);
3277 #endif
3278 
3279 	p = ___slab_alloc(s, gfpflags, node, addr, c, orig_size);
3280 #ifdef CONFIG_PREEMPT_COUNT
3281 	slub_put_cpu_ptr(s->cpu_slab);
3282 #endif
3283 	return p;
3284 }
3285 
3286 /*
3287  * If the object has been wiped upon free, make sure it's fully initialized by
3288  * zeroing out freelist pointer.
3289  */
maybe_wipe_obj_freeptr(struct kmem_cache * s,void * obj)3290 static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s,
3291 						   void *obj)
3292 {
3293 	if (unlikely(slab_want_init_on_free(s)) && obj)
3294 		memset((void *)((char *)kasan_reset_tag(obj) + s->offset),
3295 			0, sizeof(void *));
3296 }
3297 
3298 /*
3299  * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
3300  * have the fastpath folded into their functions. So no function call
3301  * overhead for requests that can be satisfied on the fastpath.
3302  *
3303  * The fastpath works by first checking if the lockless freelist can be used.
3304  * If not then __slab_alloc is called for slow processing.
3305  *
3306  * Otherwise we can simply pick the next object from the lockless free list.
3307  */
slab_alloc_node(struct kmem_cache * s,struct list_lru * lru,gfp_t gfpflags,int node,unsigned long addr,size_t orig_size)3308 static __always_inline void *slab_alloc_node(struct kmem_cache *s, struct list_lru *lru,
3309 		gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
3310 {
3311 	void *object;
3312 	struct kmem_cache_cpu *c;
3313 	struct slab *slab;
3314 	unsigned long tid;
3315 	struct obj_cgroup *objcg = NULL;
3316 	bool init = false;
3317 
3318 	s = slab_pre_alloc_hook(s, lru, &objcg, 1, gfpflags);
3319 	if (!s)
3320 		return NULL;
3321 
3322 	object = kfence_alloc(s, orig_size, gfpflags);
3323 	if (unlikely(object))
3324 		goto out;
3325 
3326 redo:
3327 	/*
3328 	 * Must read kmem_cache cpu data via this cpu ptr. Preemption is
3329 	 * enabled. We may switch back and forth between cpus while
3330 	 * reading from one cpu area. That does not matter as long
3331 	 * as we end up on the original cpu again when doing the cmpxchg.
3332 	 *
3333 	 * We must guarantee that tid and kmem_cache_cpu are retrieved on the
3334 	 * same cpu. We read first the kmem_cache_cpu pointer and use it to read
3335 	 * the tid. If we are preempted and switched to another cpu between the
3336 	 * two reads, it's OK as the two are still associated with the same cpu
3337 	 * and cmpxchg later will validate the cpu.
3338 	 */
3339 	c = raw_cpu_ptr(s->cpu_slab);
3340 	tid = READ_ONCE(c->tid);
3341 
3342 	/*
3343 	 * Irqless object alloc/free algorithm used here depends on sequence
3344 	 * of fetching cpu_slab's data. tid should be fetched before anything
3345 	 * on c to guarantee that object and slab associated with previous tid
3346 	 * won't be used with current tid. If we fetch tid first, object and
3347 	 * slab could be one associated with next tid and our alloc/free
3348 	 * request will be failed. In this case, we will retry. So, no problem.
3349 	 */
3350 	barrier();
3351 
3352 	/*
3353 	 * The transaction ids are globally unique per cpu and per operation on
3354 	 * a per cpu queue. Thus they can be guarantee that the cmpxchg_double
3355 	 * occurs on the right processor and that there was no operation on the
3356 	 * linked list in between.
3357 	 */
3358 
3359 	object = c->freelist;
3360 	slab = c->slab;
3361 
3362 	if (!USE_LOCKLESS_FAST_PATH() ||
3363 	    unlikely(!object || !slab || !node_match(slab, node))) {
3364 		object = __slab_alloc(s, gfpflags, node, addr, c, orig_size);
3365 	} else {
3366 		void *next_object = get_freepointer_safe(s, object);
3367 
3368 		/*
3369 		 * The cmpxchg will only match if there was no additional
3370 		 * operation and if we are on the right processor.
3371 		 *
3372 		 * The cmpxchg does the following atomically (without lock
3373 		 * semantics!)
3374 		 * 1. Relocate first pointer to the current per cpu area.
3375 		 * 2. Verify that tid and freelist have not been changed
3376 		 * 3. If they were not changed replace tid and freelist
3377 		 *
3378 		 * Since this is without lock semantics the protection is only
3379 		 * against code executing on this cpu *not* from access by
3380 		 * other cpus.
3381 		 */
3382 		if (unlikely(!this_cpu_cmpxchg_double(
3383 				s->cpu_slab->freelist, s->cpu_slab->tid,
3384 				object, tid,
3385 				next_object, next_tid(tid)))) {
3386 
3387 			note_cmpxchg_failure("slab_alloc", s, tid);
3388 			goto redo;
3389 		}
3390 		prefetch_freepointer(s, next_object);
3391 		stat(s, ALLOC_FASTPATH);
3392 	}
3393 
3394 	maybe_wipe_obj_freeptr(s, object);
3395 	init = slab_want_init_on_alloc(gfpflags, s);
3396 
3397 out:
3398 	slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init);
3399 
3400 	return object;
3401 }
3402 
slab_alloc(struct kmem_cache * s,struct list_lru * lru,gfp_t gfpflags,unsigned long addr,size_t orig_size)3403 static __always_inline void *slab_alloc(struct kmem_cache *s, struct list_lru *lru,
3404 		gfp_t gfpflags, unsigned long addr, size_t orig_size)
3405 {
3406 	return slab_alloc_node(s, lru, gfpflags, NUMA_NO_NODE, addr, orig_size);
3407 }
3408 
3409 static __always_inline
__kmem_cache_alloc_lru(struct kmem_cache * s,struct list_lru * lru,gfp_t gfpflags)3410 void *__kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
3411 			     gfp_t gfpflags)
3412 {
3413 	void *ret = slab_alloc(s, lru, gfpflags, _RET_IP_, s->object_size);
3414 
3415 	trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE);
3416 
3417 	return ret;
3418 }
3419 
kmem_cache_alloc(struct kmem_cache * s,gfp_t gfpflags)3420 void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
3421 {
3422 	return __kmem_cache_alloc_lru(s, NULL, gfpflags);
3423 }
3424 EXPORT_SYMBOL(kmem_cache_alloc);
3425 
kmem_cache_alloc_lru(struct kmem_cache * s,struct list_lru * lru,gfp_t gfpflags)3426 void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
3427 			   gfp_t gfpflags)
3428 {
3429 	return __kmem_cache_alloc_lru(s, lru, gfpflags);
3430 }
3431 EXPORT_SYMBOL(kmem_cache_alloc_lru);
3432 
__kmem_cache_alloc_node(struct kmem_cache * s,gfp_t gfpflags,int node,size_t orig_size,unsigned long caller)3433 void *__kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags,
3434 			      int node, size_t orig_size,
3435 			      unsigned long caller)
3436 {
3437 	return slab_alloc_node(s, NULL, gfpflags, node,
3438 			       caller, orig_size);
3439 }
3440 
kmem_cache_alloc_node(struct kmem_cache * s,gfp_t gfpflags,int node)3441 void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
3442 {
3443 	void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, s->object_size);
3444 
3445 	trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, node);
3446 
3447 	return ret;
3448 }
3449 EXPORT_SYMBOL(kmem_cache_alloc_node);
3450 
3451 /*
3452  * Slow path handling. This may still be called frequently since objects
3453  * have a longer lifetime than the cpu slabs in most processing loads.
3454  *
3455  * So we still attempt to reduce cache line usage. Just take the slab
3456  * lock and free the item. If there is no additional partial slab
3457  * handling required then we can return immediately.
3458  */
__slab_free(struct kmem_cache * s,struct slab * slab,void * head,void * tail,int cnt,unsigned long addr)3459 static void __slab_free(struct kmem_cache *s, struct slab *slab,
3460 			void *head, void *tail, int cnt,
3461 			unsigned long addr)
3462 
3463 {
3464 	void *prior;
3465 	int was_frozen;
3466 	struct slab new;
3467 	unsigned long counters;
3468 	struct kmem_cache_node *n = NULL;
3469 	unsigned long flags;
3470 
3471 	stat(s, FREE_SLOWPATH);
3472 
3473 	if (kfence_free(head))
3474 		return;
3475 
3476 	if (kmem_cache_debug(s)) {
3477 		free_debug_processing(s, slab, head, tail, cnt, addr);
3478 		return;
3479 	}
3480 
3481 	do {
3482 		if (unlikely(n)) {
3483 			spin_unlock_irqrestore(&n->list_lock, flags);
3484 			n = NULL;
3485 		}
3486 		prior = slab->freelist;
3487 		counters = slab->counters;
3488 		set_freepointer(s, tail, prior);
3489 		new.counters = counters;
3490 		was_frozen = new.frozen;
3491 		new.inuse -= cnt;
3492 		if ((!new.inuse || !prior) && !was_frozen) {
3493 
3494 			if (kmem_cache_has_cpu_partial(s) && !prior) {
3495 
3496 				/*
3497 				 * Slab was on no list before and will be
3498 				 * partially empty
3499 				 * We can defer the list move and instead
3500 				 * freeze it.
3501 				 */
3502 				new.frozen = 1;
3503 
3504 			} else { /* Needs to be taken off a list */
3505 
3506 				n = get_node(s, slab_nid(slab));
3507 				/*
3508 				 * Speculatively acquire the list_lock.
3509 				 * If the cmpxchg does not succeed then we may
3510 				 * drop the list_lock without any processing.
3511 				 *
3512 				 * Otherwise the list_lock will synchronize with
3513 				 * other processors updating the list of slabs.
3514 				 */
3515 				spin_lock_irqsave(&n->list_lock, flags);
3516 
3517 			}
3518 		}
3519 
3520 	} while (!cmpxchg_double_slab(s, slab,
3521 		prior, counters,
3522 		head, new.counters,
3523 		"__slab_free"));
3524 
3525 	if (likely(!n)) {
3526 
3527 		if (likely(was_frozen)) {
3528 			/*
3529 			 * The list lock was not taken therefore no list
3530 			 * activity can be necessary.
3531 			 */
3532 			stat(s, FREE_FROZEN);
3533 		} else if (new.frozen) {
3534 			/*
3535 			 * If we just froze the slab then put it onto the
3536 			 * per cpu partial list.
3537 			 */
3538 			put_cpu_partial(s, slab, 1);
3539 			stat(s, CPU_PARTIAL_FREE);
3540 		}
3541 
3542 		return;
3543 	}
3544 
3545 	if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
3546 		goto slab_empty;
3547 
3548 	/*
3549 	 * Objects left in the slab. If it was not on the partial list before
3550 	 * then add it.
3551 	 */
3552 	if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
3553 		remove_full(s, n, slab);
3554 		add_partial(n, slab, DEACTIVATE_TO_TAIL);
3555 		stat(s, FREE_ADD_PARTIAL);
3556 	}
3557 	spin_unlock_irqrestore(&n->list_lock, flags);
3558 	return;
3559 
3560 slab_empty:
3561 	if (prior) {
3562 		/*
3563 		 * Slab on the partial list.
3564 		 */
3565 		remove_partial(n, slab);
3566 		stat(s, FREE_REMOVE_PARTIAL);
3567 	} else {
3568 		/* Slab must be on the full list */
3569 		remove_full(s, n, slab);
3570 	}
3571 
3572 	spin_unlock_irqrestore(&n->list_lock, flags);
3573 	stat(s, FREE_SLAB);
3574 	discard_slab(s, slab);
3575 }
3576 
3577 /*
3578  * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
3579  * can perform fastpath freeing without additional function calls.
3580  *
3581  * The fastpath is only possible if we are freeing to the current cpu slab
3582  * of this processor. This typically the case if we have just allocated
3583  * the item before.
3584  *
3585  * If fastpath is not possible then fall back to __slab_free where we deal
3586  * with all sorts of special processing.
3587  *
3588  * Bulk free of a freelist with several objects (all pointing to the
3589  * same slab) possible by specifying head and tail ptr, plus objects
3590  * count (cnt). Bulk free indicated by tail pointer being set.
3591  */
do_slab_free(struct kmem_cache * s,struct slab * slab,void * head,void * tail,int cnt,unsigned long addr)3592 static __always_inline void do_slab_free(struct kmem_cache *s,
3593 				struct slab *slab, void *head, void *tail,
3594 				int cnt, unsigned long addr)
3595 {
3596 	void *tail_obj = tail ? : head;
3597 	struct kmem_cache_cpu *c;
3598 	unsigned long tid;
3599 	void **freelist;
3600 
3601 redo:
3602 	/*
3603 	 * Determine the currently cpus per cpu slab.
3604 	 * The cpu may change afterward. However that does not matter since
3605 	 * data is retrieved via this pointer. If we are on the same cpu
3606 	 * during the cmpxchg then the free will succeed.
3607 	 */
3608 	c = raw_cpu_ptr(s->cpu_slab);
3609 	tid = READ_ONCE(c->tid);
3610 
3611 	/* Same with comment on barrier() in slab_alloc_node() */
3612 	barrier();
3613 
3614 	if (unlikely(slab != c->slab)) {
3615 		__slab_free(s, slab, head, tail_obj, cnt, addr);
3616 		return;
3617 	}
3618 
3619 	if (USE_LOCKLESS_FAST_PATH()) {
3620 		freelist = READ_ONCE(c->freelist);
3621 
3622 		set_freepointer(s, tail_obj, freelist);
3623 
3624 		if (unlikely(!this_cpu_cmpxchg_double(
3625 				s->cpu_slab->freelist, s->cpu_slab->tid,
3626 				freelist, tid,
3627 				head, next_tid(tid)))) {
3628 
3629 			note_cmpxchg_failure("slab_free", s, tid);
3630 			goto redo;
3631 		}
3632 	} else {
3633 		/* Update the free list under the local lock */
3634 		local_lock(&s->cpu_slab->lock);
3635 		c = this_cpu_ptr(s->cpu_slab);
3636 		if (unlikely(slab != c->slab)) {
3637 			local_unlock(&s->cpu_slab->lock);
3638 			goto redo;
3639 		}
3640 		tid = c->tid;
3641 		freelist = c->freelist;
3642 
3643 		set_freepointer(s, tail_obj, freelist);
3644 		c->freelist = head;
3645 		c->tid = next_tid(tid);
3646 
3647 		local_unlock(&s->cpu_slab->lock);
3648 	}
3649 	stat(s, FREE_FASTPATH);
3650 }
3651 
slab_free(struct kmem_cache * s,struct slab * slab,void * head,void * tail,void ** p,int cnt,unsigned long addr)3652 static __always_inline void slab_free(struct kmem_cache *s, struct slab *slab,
3653 				      void *head, void *tail, void **p, int cnt,
3654 				      unsigned long addr)
3655 {
3656 	memcg_slab_free_hook(s, slab, p, cnt);
3657 	/*
3658 	 * With KASAN enabled slab_free_freelist_hook modifies the freelist
3659 	 * to remove objects, whose reuse must be delayed.
3660 	 */
3661 	if (slab_free_freelist_hook(s, &head, &tail, &cnt))
3662 		do_slab_free(s, slab, head, tail, cnt, addr);
3663 }
3664 
3665 #ifdef CONFIG_KASAN_GENERIC
___cache_free(struct kmem_cache * cache,void * x,unsigned long addr)3666 void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr)
3667 {
3668 	do_slab_free(cache, virt_to_slab(x), x, NULL, 1, addr);
3669 }
3670 #endif
3671 
__kmem_cache_free(struct kmem_cache * s,void * x,unsigned long caller)3672 void __kmem_cache_free(struct kmem_cache *s, void *x, unsigned long caller)
3673 {
3674 	slab_free(s, virt_to_slab(x), x, NULL, &x, 1, caller);
3675 }
3676 
kmem_cache_free(struct kmem_cache * s,void * x)3677 void kmem_cache_free(struct kmem_cache *s, void *x)
3678 {
3679 	s = cache_from_obj(s, x);
3680 	if (!s)
3681 		return;
3682 	trace_kmem_cache_free(_RET_IP_, x, s);
3683 	slab_free(s, virt_to_slab(x), x, NULL, &x, 1, _RET_IP_);
3684 }
3685 EXPORT_SYMBOL(kmem_cache_free);
3686 
3687 struct detached_freelist {
3688 	struct slab *slab;
3689 	void *tail;
3690 	void *freelist;
3691 	int cnt;
3692 	struct kmem_cache *s;
3693 };
3694 
3695 /*
3696  * This function progressively scans the array with free objects (with
3697  * a limited look ahead) and extract objects belonging to the same
3698  * slab.  It builds a detached freelist directly within the given
3699  * slab/objects.  This can happen without any need for
3700  * synchronization, because the objects are owned by running process.
3701  * The freelist is build up as a single linked list in the objects.
3702  * The idea is, that this detached freelist can then be bulk
3703  * transferred to the real freelist(s), but only requiring a single
3704  * synchronization primitive.  Look ahead in the array is limited due
3705  * to performance reasons.
3706  */
3707 static inline
build_detached_freelist(struct kmem_cache * s,size_t size,void ** p,struct detached_freelist * df)3708 int build_detached_freelist(struct kmem_cache *s, size_t size,
3709 			    void **p, struct detached_freelist *df)
3710 {
3711 	int lookahead = 3;
3712 	void *object;
3713 	struct folio *folio;
3714 	size_t same;
3715 
3716 	object = p[--size];
3717 	folio = virt_to_folio(object);
3718 	if (!s) {
3719 		/* Handle kalloc'ed objects */
3720 		if (unlikely(!folio_test_slab(folio))) {
3721 			free_large_kmalloc(folio, object);
3722 			df->slab = NULL;
3723 			return size;
3724 		}
3725 		/* Derive kmem_cache from object */
3726 		df->slab = folio_slab(folio);
3727 		df->s = df->slab->slab_cache;
3728 	} else {
3729 		df->slab = folio_slab(folio);
3730 		df->s = cache_from_obj(s, object); /* Support for memcg */
3731 	}
3732 
3733 	/* Start new detached freelist */
3734 	df->tail = object;
3735 	df->freelist = object;
3736 	df->cnt = 1;
3737 
3738 	if (is_kfence_address(object))
3739 		return size;
3740 
3741 	set_freepointer(df->s, object, NULL);
3742 
3743 	same = size;
3744 	while (size) {
3745 		object = p[--size];
3746 		/* df->slab is always set at this point */
3747 		if (df->slab == virt_to_slab(object)) {
3748 			/* Opportunity build freelist */
3749 			set_freepointer(df->s, object, df->freelist);
3750 			df->freelist = object;
3751 			df->cnt++;
3752 			same--;
3753 			if (size != same)
3754 				swap(p[size], p[same]);
3755 			continue;
3756 		}
3757 
3758 		/* Limit look ahead search */
3759 		if (!--lookahead)
3760 			break;
3761 	}
3762 
3763 	return same;
3764 }
3765 
3766 /* Note that interrupts must be enabled when calling this function. */
kmem_cache_free_bulk(struct kmem_cache * s,size_t size,void ** p)3767 void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
3768 {
3769 	if (!size)
3770 		return;
3771 
3772 	do {
3773 		struct detached_freelist df;
3774 
3775 		size = build_detached_freelist(s, size, p, &df);
3776 		if (!df.slab)
3777 			continue;
3778 
3779 		slab_free(df.s, df.slab, df.freelist, df.tail, &p[size], df.cnt,
3780 			  _RET_IP_);
3781 	} while (likely(size));
3782 }
3783 EXPORT_SYMBOL(kmem_cache_free_bulk);
3784 
3785 /* Note that interrupts must be enabled when calling this function. */
kmem_cache_alloc_bulk(struct kmem_cache * s,gfp_t flags,size_t size,void ** p)3786 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
3787 			  void **p)
3788 {
3789 	struct kmem_cache_cpu *c;
3790 	int i;
3791 	struct obj_cgroup *objcg = NULL;
3792 
3793 	/* memcg and kmem_cache debug support */
3794 	s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags);
3795 	if (unlikely(!s))
3796 		return false;
3797 	/*
3798 	 * Drain objects in the per cpu slab, while disabling local
3799 	 * IRQs, which protects against PREEMPT and interrupts
3800 	 * handlers invoking normal fastpath.
3801 	 */
3802 	c = slub_get_cpu_ptr(s->cpu_slab);
3803 	local_lock_irq(&s->cpu_slab->lock);
3804 
3805 	for (i = 0; i < size; i++) {
3806 		void *object = kfence_alloc(s, s->object_size, flags);
3807 
3808 		if (unlikely(object)) {
3809 			p[i] = object;
3810 			continue;
3811 		}
3812 
3813 		object = c->freelist;
3814 		if (unlikely(!object)) {
3815 			/*
3816 			 * We may have removed an object from c->freelist using
3817 			 * the fastpath in the previous iteration; in that case,
3818 			 * c->tid has not been bumped yet.
3819 			 * Since ___slab_alloc() may reenable interrupts while
3820 			 * allocating memory, we should bump c->tid now.
3821 			 */
3822 			c->tid = next_tid(c->tid);
3823 
3824 			local_unlock_irq(&s->cpu_slab->lock);
3825 
3826 			/*
3827 			 * Invoking slow path likely have side-effect
3828 			 * of re-populating per CPU c->freelist
3829 			 */
3830 			p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE,
3831 					    _RET_IP_, c, s->object_size);
3832 			if (unlikely(!p[i]))
3833 				goto error;
3834 
3835 			c = this_cpu_ptr(s->cpu_slab);
3836 			maybe_wipe_obj_freeptr(s, p[i]);
3837 
3838 			local_lock_irq(&s->cpu_slab->lock);
3839 
3840 			continue; /* goto for-loop */
3841 		}
3842 		c->freelist = get_freepointer(s, object);
3843 		p[i] = object;
3844 		maybe_wipe_obj_freeptr(s, p[i]);
3845 	}
3846 	c->tid = next_tid(c->tid);
3847 	local_unlock_irq(&s->cpu_slab->lock);
3848 	slub_put_cpu_ptr(s->cpu_slab);
3849 
3850 	/*
3851 	 * memcg and kmem_cache debug support and memory initialization.
3852 	 * Done outside of the IRQ disabled fastpath loop.
3853 	 */
3854 	slab_post_alloc_hook(s, objcg, flags, size, p,
3855 				slab_want_init_on_alloc(flags, s));
3856 	return i;
3857 error:
3858 	slub_put_cpu_ptr(s->cpu_slab);
3859 	slab_post_alloc_hook(s, objcg, flags, i, p, false);
3860 	kmem_cache_free_bulk(s, i, p);
3861 	return 0;
3862 }
3863 EXPORT_SYMBOL(kmem_cache_alloc_bulk);
3864 
3865 
3866 /*
3867  * Object placement in a slab is made very easy because we always start at
3868  * offset 0. If we tune the size of the object to the alignment then we can
3869  * get the required alignment by putting one properly sized object after
3870  * another.
3871  *
3872  * Notice that the allocation order determines the sizes of the per cpu
3873  * caches. Each processor has always one slab available for allocations.
3874  * Increasing the allocation order reduces the number of times that slabs
3875  * must be moved on and off the partial lists and is therefore a factor in
3876  * locking overhead.
3877  */
3878 
3879 /*
3880  * Minimum / Maximum order of slab pages. This influences locking overhead
3881  * and slab fragmentation. A higher order reduces the number of partial slabs
3882  * and increases the number of allocations possible without having to
3883  * take the list_lock.
3884  */
3885 static unsigned int slub_min_order;
3886 static unsigned int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
3887 static unsigned int slub_min_objects;
3888 
3889 /*
3890  * Calculate the order of allocation given an slab object size.
3891  *
3892  * The order of allocation has significant impact on performance and other
3893  * system components. Generally order 0 allocations should be preferred since
3894  * order 0 does not cause fragmentation in the page allocator. Larger objects
3895  * be problematic to put into order 0 slabs because there may be too much
3896  * unused space left. We go to a higher order if more than 1/16th of the slab
3897  * would be wasted.
3898  *
3899  * In order to reach satisfactory performance we must ensure that a minimum
3900  * number of objects is in one slab. Otherwise we may generate too much
3901  * activity on the partial lists which requires taking the list_lock. This is
3902  * less a concern for large slabs though which are rarely used.
3903  *
3904  * slub_max_order specifies the order where we begin to stop considering the
3905  * number of objects in a slab as critical. If we reach slub_max_order then
3906  * we try to keep the page order as low as possible. So we accept more waste
3907  * of space in favor of a small page order.
3908  *
3909  * Higher order allocations also allow the placement of more objects in a
3910  * slab and thereby reduce object handling overhead. If the user has
3911  * requested a higher minimum order then we start with that one instead of
3912  * the smallest order which will fit the object.
3913  */
calc_slab_order(unsigned int size,unsigned int min_objects,unsigned int max_order,unsigned int fract_leftover)3914 static inline unsigned int calc_slab_order(unsigned int size,
3915 		unsigned int min_objects, unsigned int max_order,
3916 		unsigned int fract_leftover)
3917 {
3918 	unsigned int min_order = slub_min_order;
3919 	unsigned int order;
3920 
3921 	if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE)
3922 		return get_order(size * MAX_OBJS_PER_PAGE) - 1;
3923 
3924 	for (order = max(min_order, (unsigned int)get_order(min_objects * size));
3925 			order <= max_order; order++) {
3926 
3927 		unsigned int slab_size = (unsigned int)PAGE_SIZE << order;
3928 		unsigned int rem;
3929 
3930 		rem = slab_size % size;
3931 
3932 		if (rem <= slab_size / fract_leftover)
3933 			break;
3934 	}
3935 
3936 	return order;
3937 }
3938 
calculate_order(unsigned int size)3939 static inline int calculate_order(unsigned int size)
3940 {
3941 	unsigned int order;
3942 	unsigned int min_objects;
3943 	unsigned int max_objects;
3944 	unsigned int nr_cpus;
3945 
3946 	/*
3947 	 * Attempt to find best configuration for a slab. This
3948 	 * works by first attempting to generate a layout with
3949 	 * the best configuration and backing off gradually.
3950 	 *
3951 	 * First we increase the acceptable waste in a slab. Then
3952 	 * we reduce the minimum objects required in a slab.
3953 	 */
3954 	min_objects = slub_min_objects;
3955 	if (!min_objects) {
3956 		/*
3957 		 * Some architectures will only update present cpus when
3958 		 * onlining them, so don't trust the number if it's just 1. But
3959 		 * we also don't want to use nr_cpu_ids always, as on some other
3960 		 * architectures, there can be many possible cpus, but never
3961 		 * onlined. Here we compromise between trying to avoid too high
3962 		 * order on systems that appear larger than they are, and too
3963 		 * low order on systems that appear smaller than they are.
3964 		 */
3965 		nr_cpus = num_present_cpus();
3966 		if (nr_cpus <= 1)
3967 			nr_cpus = nr_cpu_ids;
3968 		min_objects = 4 * (fls(nr_cpus) + 1);
3969 	}
3970 	max_objects = order_objects(slub_max_order, size);
3971 	min_objects = min(min_objects, max_objects);
3972 
3973 	while (min_objects > 1) {
3974 		unsigned int fraction;
3975 
3976 		fraction = 16;
3977 		while (fraction >= 4) {
3978 			order = calc_slab_order(size, min_objects,
3979 					slub_max_order, fraction);
3980 			if (order <= slub_max_order)
3981 				return order;
3982 			fraction /= 2;
3983 		}
3984 		min_objects--;
3985 	}
3986 
3987 	/*
3988 	 * We were unable to place multiple objects in a slab. Now
3989 	 * lets see if we can place a single object there.
3990 	 */
3991 	order = calc_slab_order(size, 1, slub_max_order, 1);
3992 	if (order <= slub_max_order)
3993 		return order;
3994 
3995 	/*
3996 	 * Doh this slab cannot be placed using slub_max_order.
3997 	 */
3998 	order = calc_slab_order(size, 1, MAX_ORDER, 1);
3999 	if (order < MAX_ORDER)
4000 		return order;
4001 	return -ENOSYS;
4002 }
4003 
4004 static void
init_kmem_cache_node(struct kmem_cache_node * n)4005 init_kmem_cache_node(struct kmem_cache_node *n)
4006 {
4007 	n->nr_partial = 0;
4008 	spin_lock_init(&n->list_lock);
4009 	INIT_LIST_HEAD(&n->partial);
4010 #ifdef CONFIG_SLUB_DEBUG
4011 	atomic_long_set(&n->nr_slabs, 0);
4012 	atomic_long_set(&n->total_objects, 0);
4013 	INIT_LIST_HEAD(&n->full);
4014 #endif
4015 }
4016 
alloc_kmem_cache_cpus(struct kmem_cache * s)4017 static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
4018 {
4019 	BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
4020 			KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
4021 
4022 	/*
4023 	 * Must align to double word boundary for the double cmpxchg
4024 	 * instructions to work; see __pcpu_double_call_return_bool().
4025 	 */
4026 	s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu),
4027 				     2 * sizeof(void *));
4028 
4029 	if (!s->cpu_slab)
4030 		return 0;
4031 
4032 	init_kmem_cache_cpus(s);
4033 
4034 	return 1;
4035 }
4036 
4037 static struct kmem_cache *kmem_cache_node;
4038 
4039 /*
4040  * No kmalloc_node yet so do it by hand. We know that this is the first
4041  * slab on the node for this slabcache. There are no concurrent accesses
4042  * possible.
4043  *
4044  * Note that this function only works on the kmem_cache_node
4045  * when allocating for the kmem_cache_node. This is used for bootstrapping
4046  * memory on a fresh node that has no slab structures yet.
4047  */
early_kmem_cache_node_alloc(int node)4048 static void early_kmem_cache_node_alloc(int node)
4049 {
4050 	struct slab *slab;
4051 	struct kmem_cache_node *n;
4052 
4053 	BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
4054 
4055 	slab = new_slab(kmem_cache_node, GFP_NOWAIT, node);
4056 
4057 	BUG_ON(!slab);
4058 	inc_slabs_node(kmem_cache_node, slab_nid(slab), slab->objects);
4059 	if (slab_nid(slab) != node) {
4060 		pr_err("SLUB: Unable to allocate memory from node %d\n", node);
4061 		pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n");
4062 	}
4063 
4064 	n = slab->freelist;
4065 	BUG_ON(!n);
4066 #ifdef CONFIG_SLUB_DEBUG
4067 	init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
4068 	init_tracking(kmem_cache_node, n);
4069 #endif
4070 	n = kasan_slab_alloc(kmem_cache_node, n, GFP_KERNEL, false);
4071 	slab->freelist = get_freepointer(kmem_cache_node, n);
4072 	slab->inuse = 1;
4073 	kmem_cache_node->node[node] = n;
4074 	init_kmem_cache_node(n);
4075 	inc_slabs_node(kmem_cache_node, node, slab->objects);
4076 
4077 	/*
4078 	 * No locks need to be taken here as it has just been
4079 	 * initialized and there is no concurrent access.
4080 	 */
4081 	__add_partial(n, slab, DEACTIVATE_TO_HEAD);
4082 }
4083 
free_kmem_cache_nodes(struct kmem_cache * s)4084 static void free_kmem_cache_nodes(struct kmem_cache *s)
4085 {
4086 	int node;
4087 	struct kmem_cache_node *n;
4088 
4089 	for_each_kmem_cache_node(s, node, n) {
4090 		s->node[node] = NULL;
4091 		kmem_cache_free(kmem_cache_node, n);
4092 	}
4093 }
4094 
__kmem_cache_release(struct kmem_cache * s)4095 void __kmem_cache_release(struct kmem_cache *s)
4096 {
4097 	cache_random_seq_destroy(s);
4098 	free_percpu(s->cpu_slab);
4099 	free_kmem_cache_nodes(s);
4100 }
4101 
init_kmem_cache_nodes(struct kmem_cache * s)4102 static int init_kmem_cache_nodes(struct kmem_cache *s)
4103 {
4104 	int node;
4105 
4106 	for_each_node_mask(node, slab_nodes) {
4107 		struct kmem_cache_node *n;
4108 
4109 		if (slab_state == DOWN) {
4110 			early_kmem_cache_node_alloc(node);
4111 			continue;
4112 		}
4113 		n = kmem_cache_alloc_node(kmem_cache_node,
4114 						GFP_KERNEL, node);
4115 
4116 		if (!n) {
4117 			free_kmem_cache_nodes(s);
4118 			return 0;
4119 		}
4120 
4121 		init_kmem_cache_node(n);
4122 		s->node[node] = n;
4123 	}
4124 	return 1;
4125 }
4126 
set_cpu_partial(struct kmem_cache * s)4127 static void set_cpu_partial(struct kmem_cache *s)
4128 {
4129 #ifdef CONFIG_SLUB_CPU_PARTIAL
4130 	unsigned int nr_objects;
4131 
4132 	/*
4133 	 * cpu_partial determined the maximum number of objects kept in the
4134 	 * per cpu partial lists of a processor.
4135 	 *
4136 	 * Per cpu partial lists mainly contain slabs that just have one
4137 	 * object freed. If they are used for allocation then they can be
4138 	 * filled up again with minimal effort. The slab will never hit the
4139 	 * per node partial lists and therefore no locking will be required.
4140 	 *
4141 	 * For backwards compatibility reasons, this is determined as number
4142 	 * of objects, even though we now limit maximum number of pages, see
4143 	 * slub_set_cpu_partial()
4144 	 */
4145 	if (!kmem_cache_has_cpu_partial(s))
4146 		nr_objects = 0;
4147 	else if (s->size >= PAGE_SIZE)
4148 		nr_objects = 6;
4149 	else if (s->size >= 1024)
4150 		nr_objects = 24;
4151 	else if (s->size >= 256)
4152 		nr_objects = 52;
4153 	else
4154 		nr_objects = 120;
4155 
4156 	slub_set_cpu_partial(s, nr_objects);
4157 #endif
4158 }
4159 
4160 /*
4161  * calculate_sizes() determines the order and the distribution of data within
4162  * a slab object.
4163  */
calculate_sizes(struct kmem_cache * s)4164 static int calculate_sizes(struct kmem_cache *s)
4165 {
4166 	slab_flags_t flags = s->flags;
4167 	unsigned int size = s->object_size;
4168 	unsigned int order;
4169 
4170 	/*
4171 	 * Round up object size to the next word boundary. We can only
4172 	 * place the free pointer at word boundaries and this determines
4173 	 * the possible location of the free pointer.
4174 	 */
4175 	size = ALIGN(size, sizeof(void *));
4176 
4177 #ifdef CONFIG_SLUB_DEBUG
4178 	/*
4179 	 * Determine if we can poison the object itself. If the user of
4180 	 * the slab may touch the object after free or before allocation
4181 	 * then we should never poison the object itself.
4182 	 */
4183 	if ((flags & SLAB_POISON) && !(flags & SLAB_TYPESAFE_BY_RCU) &&
4184 			!s->ctor)
4185 		s->flags |= __OBJECT_POISON;
4186 	else
4187 		s->flags &= ~__OBJECT_POISON;
4188 
4189 
4190 	/*
4191 	 * If we are Redzoning then check if there is some space between the
4192 	 * end of the object and the free pointer. If not then add an
4193 	 * additional word to have some bytes to store Redzone information.
4194 	 */
4195 	if ((flags & SLAB_RED_ZONE) && size == s->object_size)
4196 		size += sizeof(void *);
4197 #endif
4198 
4199 	/*
4200 	 * With that we have determined the number of bytes in actual use
4201 	 * by the object and redzoning.
4202 	 */
4203 	s->inuse = size;
4204 
4205 	if ((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
4206 	    ((flags & SLAB_RED_ZONE) && s->object_size < sizeof(void *)) ||
4207 	    s->ctor) {
4208 		/*
4209 		 * Relocate free pointer after the object if it is not
4210 		 * permitted to overwrite the first word of the object on
4211 		 * kmem_cache_free.
4212 		 *
4213 		 * This is the case if we do RCU, have a constructor or
4214 		 * destructor, are poisoning the objects, or are
4215 		 * redzoning an object smaller than sizeof(void *).
4216 		 *
4217 		 * The assumption that s->offset >= s->inuse means free
4218 		 * pointer is outside of the object is used in the
4219 		 * freeptr_outside_object() function. If that is no
4220 		 * longer true, the function needs to be modified.
4221 		 */
4222 		s->offset = size;
4223 		size += sizeof(void *);
4224 	} else {
4225 		/*
4226 		 * Store freelist pointer near middle of object to keep
4227 		 * it away from the edges of the object to avoid small
4228 		 * sized over/underflows from neighboring allocations.
4229 		 */
4230 		s->offset = ALIGN_DOWN(s->object_size / 2, sizeof(void *));
4231 	}
4232 
4233 #ifdef CONFIG_SLUB_DEBUG
4234 	if (flags & SLAB_STORE_USER) {
4235 		/*
4236 		 * Need to store information about allocs and frees after
4237 		 * the object.
4238 		 */
4239 		size += 2 * sizeof(struct track);
4240 
4241 		/* Save the original kmalloc request size */
4242 		if (flags & SLAB_KMALLOC)
4243 			size += sizeof(unsigned int);
4244 	}
4245 #endif
4246 
4247 	kasan_cache_create(s, &size, &s->flags);
4248 #ifdef CONFIG_SLUB_DEBUG
4249 	if (flags & SLAB_RED_ZONE) {
4250 		/*
4251 		 * Add some empty padding so that we can catch
4252 		 * overwrites from earlier objects rather than let
4253 		 * tracking information or the free pointer be
4254 		 * corrupted if a user writes before the start
4255 		 * of the object.
4256 		 */
4257 		size += sizeof(void *);
4258 
4259 		s->red_left_pad = sizeof(void *);
4260 		s->red_left_pad = ALIGN(s->red_left_pad, s->align);
4261 		size += s->red_left_pad;
4262 	}
4263 #endif
4264 
4265 	/*
4266 	 * SLUB stores one object immediately after another beginning from
4267 	 * offset 0. In order to align the objects we have to simply size
4268 	 * each object to conform to the alignment.
4269 	 */
4270 	size = ALIGN(size, s->align);
4271 	s->size = size;
4272 	s->reciprocal_size = reciprocal_value(size);
4273 	order = calculate_order(size);
4274 
4275 	if ((int)order < 0)
4276 		return 0;
4277 
4278 	s->allocflags = 0;
4279 	if (order)
4280 		s->allocflags |= __GFP_COMP;
4281 
4282 	if (s->flags & SLAB_CACHE_DMA)
4283 		s->allocflags |= GFP_DMA;
4284 
4285 	if (s->flags & SLAB_CACHE_DMA32)
4286 		s->allocflags |= GFP_DMA32;
4287 
4288 	if (s->flags & SLAB_RECLAIM_ACCOUNT)
4289 		s->allocflags |= __GFP_RECLAIMABLE;
4290 
4291 	/*
4292 	 * Determine the number of objects per slab
4293 	 */
4294 	s->oo = oo_make(order, size);
4295 	s->min = oo_make(get_order(size), size);
4296 
4297 	return !!oo_objects(s->oo);
4298 }
4299 
kmem_cache_open(struct kmem_cache * s,slab_flags_t flags)4300 static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
4301 {
4302 	s->flags = kmem_cache_flags(s->size, flags, s->name);
4303 #ifdef CONFIG_SLAB_FREELIST_HARDENED
4304 	s->random = get_random_long();
4305 #endif
4306 
4307 	if (!calculate_sizes(s))
4308 		goto error;
4309 	if (disable_higher_order_debug) {
4310 		/*
4311 		 * Disable debugging flags that store metadata if the min slab
4312 		 * order increased.
4313 		 */
4314 		if (get_order(s->size) > get_order(s->object_size)) {
4315 			s->flags &= ~DEBUG_METADATA_FLAGS;
4316 			s->offset = 0;
4317 			if (!calculate_sizes(s))
4318 				goto error;
4319 		}
4320 	}
4321 
4322 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
4323     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
4324 	if (system_has_cmpxchg_double() && (s->flags & SLAB_NO_CMPXCHG) == 0)
4325 		/* Enable fast mode */
4326 		s->flags |= __CMPXCHG_DOUBLE;
4327 #endif
4328 
4329 	/*
4330 	 * The larger the object size is, the more slabs we want on the partial
4331 	 * list to avoid pounding the page allocator excessively.
4332 	 */
4333 	s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2);
4334 	s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial);
4335 
4336 	set_cpu_partial(s);
4337 
4338 #ifdef CONFIG_NUMA
4339 	s->remote_node_defrag_ratio = 1000;
4340 #endif
4341 
4342 	/* Initialize the pre-computed randomized freelist if slab is up */
4343 	if (slab_state >= UP) {
4344 		if (init_cache_random_seq(s))
4345 			goto error;
4346 	}
4347 
4348 	if (!init_kmem_cache_nodes(s))
4349 		goto error;
4350 
4351 	if (alloc_kmem_cache_cpus(s))
4352 		return 0;
4353 
4354 error:
4355 	__kmem_cache_release(s);
4356 	return -EINVAL;
4357 }
4358 
list_slab_objects(struct kmem_cache * s,struct slab * slab,const char * text)4359 static void list_slab_objects(struct kmem_cache *s, struct slab *slab,
4360 			      const char *text)
4361 {
4362 #ifdef CONFIG_SLUB_DEBUG
4363 	void *addr = slab_address(slab);
4364 	void *p;
4365 
4366 	slab_err(s, slab, text, s->name);
4367 
4368 	spin_lock(&object_map_lock);
4369 	__fill_map(object_map, s, slab);
4370 
4371 	for_each_object(p, s, addr, slab->objects) {
4372 
4373 		if (!test_bit(__obj_to_index(s, addr, p), object_map)) {
4374 			pr_err("Object 0x%p @offset=%tu\n", p, p - addr);
4375 			print_tracking(s, p);
4376 		}
4377 	}
4378 	spin_unlock(&object_map_lock);
4379 #endif
4380 }
4381 
4382 /*
4383  * Attempt to free all partial slabs on a node.
4384  * This is called from __kmem_cache_shutdown(). We must take list_lock
4385  * because sysfs file might still access partial list after the shutdowning.
4386  */
free_partial(struct kmem_cache * s,struct kmem_cache_node * n)4387 static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
4388 {
4389 	LIST_HEAD(discard);
4390 	struct slab *slab, *h;
4391 
4392 	BUG_ON(irqs_disabled());
4393 	spin_lock_irq(&n->list_lock);
4394 	list_for_each_entry_safe(slab, h, &n->partial, slab_list) {
4395 		if (!slab->inuse) {
4396 			remove_partial(n, slab);
4397 			list_add(&slab->slab_list, &discard);
4398 		} else {
4399 			list_slab_objects(s, slab,
4400 			  "Objects remaining in %s on __kmem_cache_shutdown()");
4401 		}
4402 	}
4403 	spin_unlock_irq(&n->list_lock);
4404 
4405 	list_for_each_entry_safe(slab, h, &discard, slab_list)
4406 		discard_slab(s, slab);
4407 }
4408 
__kmem_cache_empty(struct kmem_cache * s)4409 bool __kmem_cache_empty(struct kmem_cache *s)
4410 {
4411 	int node;
4412 	struct kmem_cache_node *n;
4413 
4414 	for_each_kmem_cache_node(s, node, n)
4415 		if (n->nr_partial || slabs_node(s, node))
4416 			return false;
4417 	return true;
4418 }
4419 
4420 /*
4421  * Release all resources used by a slab cache.
4422  */
__kmem_cache_shutdown(struct kmem_cache * s)4423 int __kmem_cache_shutdown(struct kmem_cache *s)
4424 {
4425 	int node;
4426 	struct kmem_cache_node *n;
4427 
4428 	flush_all_cpus_locked(s);
4429 	/* Attempt to free all objects */
4430 	for_each_kmem_cache_node(s, node, n) {
4431 		free_partial(s, n);
4432 		if (n->nr_partial || slabs_node(s, node))
4433 			return 1;
4434 	}
4435 	return 0;
4436 }
4437 
4438 #ifdef CONFIG_PRINTK
__kmem_obj_info(struct kmem_obj_info * kpp,void * object,struct slab * slab)4439 void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
4440 {
4441 	void *base;
4442 	int __maybe_unused i;
4443 	unsigned int objnr;
4444 	void *objp;
4445 	void *objp0;
4446 	struct kmem_cache *s = slab->slab_cache;
4447 	struct track __maybe_unused *trackp;
4448 
4449 	kpp->kp_ptr = object;
4450 	kpp->kp_slab = slab;
4451 	kpp->kp_slab_cache = s;
4452 	base = slab_address(slab);
4453 	objp0 = kasan_reset_tag(object);
4454 #ifdef CONFIG_SLUB_DEBUG
4455 	objp = restore_red_left(s, objp0);
4456 #else
4457 	objp = objp0;
4458 #endif
4459 	objnr = obj_to_index(s, slab, objp);
4460 	kpp->kp_data_offset = (unsigned long)((char *)objp0 - (char *)objp);
4461 	objp = base + s->size * objnr;
4462 	kpp->kp_objp = objp;
4463 	if (WARN_ON_ONCE(objp < base || objp >= base + slab->objects * s->size
4464 			 || (objp - base) % s->size) ||
4465 	    !(s->flags & SLAB_STORE_USER))
4466 		return;
4467 #ifdef CONFIG_SLUB_DEBUG
4468 	objp = fixup_red_left(s, objp);
4469 	trackp = get_track(s, objp, TRACK_ALLOC);
4470 	kpp->kp_ret = (void *)trackp->addr;
4471 #ifdef CONFIG_STACKDEPOT
4472 	{
4473 		depot_stack_handle_t handle;
4474 		unsigned long *entries;
4475 		unsigned int nr_entries;
4476 
4477 		handle = READ_ONCE(trackp->handle);
4478 		if (handle) {
4479 			nr_entries = stack_depot_fetch(handle, &entries);
4480 			for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
4481 				kpp->kp_stack[i] = (void *)entries[i];
4482 		}
4483 
4484 		trackp = get_track(s, objp, TRACK_FREE);
4485 		handle = READ_ONCE(trackp->handle);
4486 		if (handle) {
4487 			nr_entries = stack_depot_fetch(handle, &entries);
4488 			for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
4489 				kpp->kp_free_stack[i] = (void *)entries[i];
4490 		}
4491 	}
4492 #endif
4493 #endif
4494 }
4495 #endif
4496 
4497 /********************************************************************
4498  *		Kmalloc subsystem
4499  *******************************************************************/
4500 
setup_slub_min_order(char * str)4501 static int __init setup_slub_min_order(char *str)
4502 {
4503 	get_option(&str, (int *)&slub_min_order);
4504 
4505 	return 1;
4506 }
4507 
4508 __setup("slub_min_order=", setup_slub_min_order);
4509 
setup_slub_max_order(char * str)4510 static int __init setup_slub_max_order(char *str)
4511 {
4512 	get_option(&str, (int *)&slub_max_order);
4513 	slub_max_order = min(slub_max_order, (unsigned int)MAX_ORDER - 1);
4514 
4515 	return 1;
4516 }
4517 
4518 __setup("slub_max_order=", setup_slub_max_order);
4519 
setup_slub_min_objects(char * str)4520 static int __init setup_slub_min_objects(char *str)
4521 {
4522 	get_option(&str, (int *)&slub_min_objects);
4523 
4524 	return 1;
4525 }
4526 
4527 __setup("slub_min_objects=", setup_slub_min_objects);
4528 
4529 #ifdef CONFIG_HARDENED_USERCOPY
4530 /*
4531  * Rejects incorrectly sized objects and objects that are to be copied
4532  * to/from userspace but do not fall entirely within the containing slab
4533  * cache's usercopy region.
4534  *
4535  * Returns NULL if check passes, otherwise const char * to name of cache
4536  * to indicate an error.
4537  */
__check_heap_object(const void * ptr,unsigned long n,const struct slab * slab,bool to_user)4538 void __check_heap_object(const void *ptr, unsigned long n,
4539 			 const struct slab *slab, bool to_user)
4540 {
4541 	struct kmem_cache *s;
4542 	unsigned int offset;
4543 	bool is_kfence = is_kfence_address(ptr);
4544 
4545 	ptr = kasan_reset_tag(ptr);
4546 
4547 	/* Find object and usable object size. */
4548 	s = slab->slab_cache;
4549 
4550 	/* Reject impossible pointers. */
4551 	if (ptr < slab_address(slab))
4552 		usercopy_abort("SLUB object not in SLUB page?!", NULL,
4553 			       to_user, 0, n);
4554 
4555 	/* Find offset within object. */
4556 	if (is_kfence)
4557 		offset = ptr - kfence_object_start(ptr);
4558 	else
4559 		offset = (ptr - slab_address(slab)) % s->size;
4560 
4561 	/* Adjust for redzone and reject if within the redzone. */
4562 	if (!is_kfence && kmem_cache_debug_flags(s, SLAB_RED_ZONE)) {
4563 		if (offset < s->red_left_pad)
4564 			usercopy_abort("SLUB object in left red zone",
4565 				       s->name, to_user, offset, n);
4566 		offset -= s->red_left_pad;
4567 	}
4568 
4569 	/* Allow address range falling entirely within usercopy region. */
4570 	if (offset >= s->useroffset &&
4571 	    offset - s->useroffset <= s->usersize &&
4572 	    n <= s->useroffset - offset + s->usersize)
4573 		return;
4574 
4575 	usercopy_abort("SLUB object", s->name, to_user, offset, n);
4576 }
4577 #endif /* CONFIG_HARDENED_USERCOPY */
4578 
4579 #define SHRINK_PROMOTE_MAX 32
4580 
4581 /*
4582  * kmem_cache_shrink discards empty slabs and promotes the slabs filled
4583  * up most to the head of the partial lists. New allocations will then
4584  * fill those up and thus they can be removed from the partial lists.
4585  *
4586  * The slabs with the least items are placed last. This results in them
4587  * being allocated from last increasing the chance that the last objects
4588  * are freed in them.
4589  */
__kmem_cache_do_shrink(struct kmem_cache * s)4590 static int __kmem_cache_do_shrink(struct kmem_cache *s)
4591 {
4592 	int node;
4593 	int i;
4594 	struct kmem_cache_node *n;
4595 	struct slab *slab;
4596 	struct slab *t;
4597 	struct list_head discard;
4598 	struct list_head promote[SHRINK_PROMOTE_MAX];
4599 	unsigned long flags;
4600 	int ret = 0;
4601 
4602 	for_each_kmem_cache_node(s, node, n) {
4603 		INIT_LIST_HEAD(&discard);
4604 		for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
4605 			INIT_LIST_HEAD(promote + i);
4606 
4607 		spin_lock_irqsave(&n->list_lock, flags);
4608 
4609 		/*
4610 		 * Build lists of slabs to discard or promote.
4611 		 *
4612 		 * Note that concurrent frees may occur while we hold the
4613 		 * list_lock. slab->inuse here is the upper limit.
4614 		 */
4615 		list_for_each_entry_safe(slab, t, &n->partial, slab_list) {
4616 			int free = slab->objects - slab->inuse;
4617 
4618 			/* Do not reread slab->inuse */
4619 			barrier();
4620 
4621 			/* We do not keep full slabs on the list */
4622 			BUG_ON(free <= 0);
4623 
4624 			if (free == slab->objects) {
4625 				list_move(&slab->slab_list, &discard);
4626 				n->nr_partial--;
4627 				dec_slabs_node(s, node, slab->objects);
4628 			} else if (free <= SHRINK_PROMOTE_MAX)
4629 				list_move(&slab->slab_list, promote + free - 1);
4630 		}
4631 
4632 		/*
4633 		 * Promote the slabs filled up most to the head of the
4634 		 * partial list.
4635 		 */
4636 		for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
4637 			list_splice(promote + i, &n->partial);
4638 
4639 		spin_unlock_irqrestore(&n->list_lock, flags);
4640 
4641 		/* Release empty slabs */
4642 		list_for_each_entry_safe(slab, t, &discard, slab_list)
4643 			free_slab(s, slab);
4644 
4645 		if (slabs_node(s, node))
4646 			ret = 1;
4647 	}
4648 
4649 	return ret;
4650 }
4651 
__kmem_cache_shrink(struct kmem_cache * s)4652 int __kmem_cache_shrink(struct kmem_cache *s)
4653 {
4654 	flush_all(s);
4655 	return __kmem_cache_do_shrink(s);
4656 }
4657 
slab_mem_going_offline_callback(void * arg)4658 static int slab_mem_going_offline_callback(void *arg)
4659 {
4660 	struct kmem_cache *s;
4661 
4662 	mutex_lock(&slab_mutex);
4663 	list_for_each_entry(s, &slab_caches, list) {
4664 		flush_all_cpus_locked(s);
4665 		__kmem_cache_do_shrink(s);
4666 	}
4667 	mutex_unlock(&slab_mutex);
4668 
4669 	return 0;
4670 }
4671 
slab_mem_offline_callback(void * arg)4672 static void slab_mem_offline_callback(void *arg)
4673 {
4674 	struct memory_notify *marg = arg;
4675 	int offline_node;
4676 
4677 	offline_node = marg->status_change_nid_normal;
4678 
4679 	/*
4680 	 * If the node still has available memory. we need kmem_cache_node
4681 	 * for it yet.
4682 	 */
4683 	if (offline_node < 0)
4684 		return;
4685 
4686 	mutex_lock(&slab_mutex);
4687 	node_clear(offline_node, slab_nodes);
4688 	/*
4689 	 * We no longer free kmem_cache_node structures here, as it would be
4690 	 * racy with all get_node() users, and infeasible to protect them with
4691 	 * slab_mutex.
4692 	 */
4693 	mutex_unlock(&slab_mutex);
4694 }
4695 
slab_mem_going_online_callback(void * arg)4696 static int slab_mem_going_online_callback(void *arg)
4697 {
4698 	struct kmem_cache_node *n;
4699 	struct kmem_cache *s;
4700 	struct memory_notify *marg = arg;
4701 	int nid = marg->status_change_nid_normal;
4702 	int ret = 0;
4703 
4704 	/*
4705 	 * If the node's memory is already available, then kmem_cache_node is
4706 	 * already created. Nothing to do.
4707 	 */
4708 	if (nid < 0)
4709 		return 0;
4710 
4711 	/*
4712 	 * We are bringing a node online. No memory is available yet. We must
4713 	 * allocate a kmem_cache_node structure in order to bring the node
4714 	 * online.
4715 	 */
4716 	mutex_lock(&slab_mutex);
4717 	list_for_each_entry(s, &slab_caches, list) {
4718 		/*
4719 		 * The structure may already exist if the node was previously
4720 		 * onlined and offlined.
4721 		 */
4722 		if (get_node(s, nid))
4723 			continue;
4724 		/*
4725 		 * XXX: kmem_cache_alloc_node will fallback to other nodes
4726 		 *      since memory is not yet available from the node that
4727 		 *      is brought up.
4728 		 */
4729 		n = kmem_cache_alloc(kmem_cache_node, GFP_KERNEL);
4730 		if (!n) {
4731 			ret = -ENOMEM;
4732 			goto out;
4733 		}
4734 		init_kmem_cache_node(n);
4735 		s->node[nid] = n;
4736 	}
4737 	/*
4738 	 * Any cache created after this point will also have kmem_cache_node
4739 	 * initialized for the new node.
4740 	 */
4741 	node_set(nid, slab_nodes);
4742 out:
4743 	mutex_unlock(&slab_mutex);
4744 	return ret;
4745 }
4746 
slab_memory_callback(struct notifier_block * self,unsigned long action,void * arg)4747 static int slab_memory_callback(struct notifier_block *self,
4748 				unsigned long action, void *arg)
4749 {
4750 	int ret = 0;
4751 
4752 	switch (action) {
4753 	case MEM_GOING_ONLINE:
4754 		ret = slab_mem_going_online_callback(arg);
4755 		break;
4756 	case MEM_GOING_OFFLINE:
4757 		ret = slab_mem_going_offline_callback(arg);
4758 		break;
4759 	case MEM_OFFLINE:
4760 	case MEM_CANCEL_ONLINE:
4761 		slab_mem_offline_callback(arg);
4762 		break;
4763 	case MEM_ONLINE:
4764 	case MEM_CANCEL_OFFLINE:
4765 		break;
4766 	}
4767 	if (ret)
4768 		ret = notifier_from_errno(ret);
4769 	else
4770 		ret = NOTIFY_OK;
4771 	return ret;
4772 }
4773 
4774 static struct notifier_block slab_memory_callback_nb = {
4775 	.notifier_call = slab_memory_callback,
4776 	.priority = SLAB_CALLBACK_PRI,
4777 };
4778 
4779 /********************************************************************
4780  *			Basic setup of slabs
4781  *******************************************************************/
4782 
4783 /*
4784  * Used for early kmem_cache structures that were allocated using
4785  * the page allocator. Allocate them properly then fix up the pointers
4786  * that may be pointing to the wrong kmem_cache structure.
4787  */
4788 
bootstrap(struct kmem_cache * static_cache)4789 static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
4790 {
4791 	int node;
4792 	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
4793 	struct kmem_cache_node *n;
4794 
4795 	memcpy(s, static_cache, kmem_cache->object_size);
4796 
4797 	/*
4798 	 * This runs very early, and only the boot processor is supposed to be
4799 	 * up.  Even if it weren't true, IRQs are not up so we couldn't fire
4800 	 * IPIs around.
4801 	 */
4802 	__flush_cpu_slab(s, smp_processor_id());
4803 	for_each_kmem_cache_node(s, node, n) {
4804 		struct slab *p;
4805 
4806 		list_for_each_entry(p, &n->partial, slab_list)
4807 			p->slab_cache = s;
4808 
4809 #ifdef CONFIG_SLUB_DEBUG
4810 		list_for_each_entry(p, &n->full, slab_list)
4811 			p->slab_cache = s;
4812 #endif
4813 	}
4814 	list_add(&s->list, &slab_caches);
4815 	return s;
4816 }
4817 
kmem_cache_init(void)4818 void __init kmem_cache_init(void)
4819 {
4820 	static __initdata struct kmem_cache boot_kmem_cache,
4821 		boot_kmem_cache_node;
4822 	int node;
4823 
4824 	if (debug_guardpage_minorder())
4825 		slub_max_order = 0;
4826 
4827 	/* Print slub debugging pointers without hashing */
4828 	if (__slub_debug_enabled())
4829 		no_hash_pointers_enable(NULL);
4830 
4831 	kmem_cache_node = &boot_kmem_cache_node;
4832 	kmem_cache = &boot_kmem_cache;
4833 
4834 	/*
4835 	 * Initialize the nodemask for which we will allocate per node
4836 	 * structures. Here we don't need taking slab_mutex yet.
4837 	 */
4838 	for_each_node_state(node, N_NORMAL_MEMORY)
4839 		node_set(node, slab_nodes);
4840 
4841 	create_boot_cache(kmem_cache_node, "kmem_cache_node",
4842 		sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0);
4843 
4844 	register_hotmemory_notifier(&slab_memory_callback_nb);
4845 
4846 	/* Able to allocate the per node structures */
4847 	slab_state = PARTIAL;
4848 
4849 	create_boot_cache(kmem_cache, "kmem_cache",
4850 			offsetof(struct kmem_cache, node) +
4851 				nr_node_ids * sizeof(struct kmem_cache_node *),
4852 		       SLAB_HWCACHE_ALIGN, 0, 0);
4853 
4854 	kmem_cache = bootstrap(&boot_kmem_cache);
4855 	kmem_cache_node = bootstrap(&boot_kmem_cache_node);
4856 
4857 	/* Now we can use the kmem_cache to allocate kmalloc slabs */
4858 	setup_kmalloc_cache_index_table();
4859 	create_kmalloc_caches(0);
4860 
4861 	/* Setup random freelists for each cache */
4862 	init_freelist_randomization();
4863 
4864 	cpuhp_setup_state_nocalls(CPUHP_SLUB_DEAD, "slub:dead", NULL,
4865 				  slub_cpu_dead);
4866 
4867 	pr_info("SLUB: HWalign=%d, Order=%u-%u, MinObjects=%u, CPUs=%u, Nodes=%u\n",
4868 		cache_line_size(),
4869 		slub_min_order, slub_max_order, slub_min_objects,
4870 		nr_cpu_ids, nr_node_ids);
4871 }
4872 
kmem_cache_init_late(void)4873 void __init kmem_cache_init_late(void)
4874 {
4875 	flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0);
4876 	WARN_ON(!flushwq);
4877 }
4878 
4879 struct kmem_cache *
__kmem_cache_alias(const char * name,unsigned int size,unsigned int align,slab_flags_t flags,void (* ctor)(void *))4880 __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
4881 		   slab_flags_t flags, void (*ctor)(void *))
4882 {
4883 	struct kmem_cache *s;
4884 
4885 	s = find_mergeable(size, align, flags, name, ctor);
4886 	if (s) {
4887 		if (sysfs_slab_alias(s, name))
4888 			return NULL;
4889 
4890 		s->refcount++;
4891 
4892 		/*
4893 		 * Adjust the object sizes so that we clear
4894 		 * the complete object on kzalloc.
4895 		 */
4896 		s->object_size = max(s->object_size, size);
4897 		s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
4898 	}
4899 
4900 	return s;
4901 }
4902 
__kmem_cache_create(struct kmem_cache * s,slab_flags_t flags)4903 int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
4904 {
4905 	int err;
4906 
4907 	err = kmem_cache_open(s, flags);
4908 	if (err)
4909 		return err;
4910 
4911 	/* Mutex is not taken during early boot */
4912 	if (slab_state <= UP)
4913 		return 0;
4914 
4915 	err = sysfs_slab_add(s);
4916 	if (err) {
4917 		__kmem_cache_release(s);
4918 		return err;
4919 	}
4920 
4921 	if (s->flags & SLAB_STORE_USER)
4922 		debugfs_slab_add(s);
4923 
4924 	return 0;
4925 }
4926 
4927 #ifdef CONFIG_SYSFS
count_inuse(struct slab * slab)4928 static int count_inuse(struct slab *slab)
4929 {
4930 	return slab->inuse;
4931 }
4932 
count_total(struct slab * slab)4933 static int count_total(struct slab *slab)
4934 {
4935 	return slab->objects;
4936 }
4937 #endif
4938 
4939 #ifdef CONFIG_SLUB_DEBUG
validate_slab(struct kmem_cache * s,struct slab * slab,unsigned long * obj_map)4940 static void validate_slab(struct kmem_cache *s, struct slab *slab,
4941 			  unsigned long *obj_map)
4942 {
4943 	void *p;
4944 	void *addr = slab_address(slab);
4945 
4946 	if (!check_slab(s, slab) || !on_freelist(s, slab, NULL))
4947 		return;
4948 
4949 	/* Now we know that a valid freelist exists */
4950 	__fill_map(obj_map, s, slab);
4951 	for_each_object(p, s, addr, slab->objects) {
4952 		u8 val = test_bit(__obj_to_index(s, addr, p), obj_map) ?
4953 			 SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
4954 
4955 		if (!check_object(s, slab, p, val))
4956 			break;
4957 	}
4958 }
4959 
validate_slab_node(struct kmem_cache * s,struct kmem_cache_node * n,unsigned long * obj_map)4960 static int validate_slab_node(struct kmem_cache *s,
4961 		struct kmem_cache_node *n, unsigned long *obj_map)
4962 {
4963 	unsigned long count = 0;
4964 	struct slab *slab;
4965 	unsigned long flags;
4966 
4967 	spin_lock_irqsave(&n->list_lock, flags);
4968 
4969 	list_for_each_entry(slab, &n->partial, slab_list) {
4970 		validate_slab(s, slab, obj_map);
4971 		count++;
4972 	}
4973 	if (count != n->nr_partial) {
4974 		pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
4975 		       s->name, count, n->nr_partial);
4976 		slab_add_kunit_errors();
4977 	}
4978 
4979 	if (!(s->flags & SLAB_STORE_USER))
4980 		goto out;
4981 
4982 	list_for_each_entry(slab, &n->full, slab_list) {
4983 		validate_slab(s, slab, obj_map);
4984 		count++;
4985 	}
4986 	if (count != atomic_long_read(&n->nr_slabs)) {
4987 		pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
4988 		       s->name, count, atomic_long_read(&n->nr_slabs));
4989 		slab_add_kunit_errors();
4990 	}
4991 
4992 out:
4993 	spin_unlock_irqrestore(&n->list_lock, flags);
4994 	return count;
4995 }
4996 
validate_slab_cache(struct kmem_cache * s)4997 long validate_slab_cache(struct kmem_cache *s)
4998 {
4999 	int node;
5000 	unsigned long count = 0;
5001 	struct kmem_cache_node *n;
5002 	unsigned long *obj_map;
5003 
5004 	obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
5005 	if (!obj_map)
5006 		return -ENOMEM;
5007 
5008 	flush_all(s);
5009 	for_each_kmem_cache_node(s, node, n)
5010 		count += validate_slab_node(s, n, obj_map);
5011 
5012 	bitmap_free(obj_map);
5013 
5014 	return count;
5015 }
5016 EXPORT_SYMBOL(validate_slab_cache);
5017 
5018 #ifdef CONFIG_DEBUG_FS
5019 /*
5020  * Generate lists of code addresses where slabcache objects are allocated
5021  * and freed.
5022  */
5023 
5024 struct location {
5025 	depot_stack_handle_t handle;
5026 	unsigned long count;
5027 	unsigned long addr;
5028 	unsigned long waste;
5029 	long long sum_time;
5030 	long min_time;
5031 	long max_time;
5032 	long min_pid;
5033 	long max_pid;
5034 	DECLARE_BITMAP(cpus, NR_CPUS);
5035 	nodemask_t nodes;
5036 };
5037 
5038 struct loc_track {
5039 	unsigned long max;
5040 	unsigned long count;
5041 	struct location *loc;
5042 	loff_t idx;
5043 };
5044 
5045 static struct dentry *slab_debugfs_root;
5046 
free_loc_track(struct loc_track * t)5047 static void free_loc_track(struct loc_track *t)
5048 {
5049 	if (t->max)
5050 		free_pages((unsigned long)t->loc,
5051 			get_order(sizeof(struct location) * t->max));
5052 }
5053 
alloc_loc_track(struct loc_track * t,unsigned long max,gfp_t flags)5054 static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
5055 {
5056 	struct location *l;
5057 	int order;
5058 
5059 	order = get_order(sizeof(struct location) * max);
5060 
5061 	l = (void *)__get_free_pages(flags, order);
5062 	if (!l)
5063 		return 0;
5064 
5065 	if (t->count) {
5066 		memcpy(l, t->loc, sizeof(struct location) * t->count);
5067 		free_loc_track(t);
5068 	}
5069 	t->max = max;
5070 	t->loc = l;
5071 	return 1;
5072 }
5073 
add_location(struct loc_track * t,struct kmem_cache * s,const struct track * track,unsigned int orig_size)5074 static int add_location(struct loc_track *t, struct kmem_cache *s,
5075 				const struct track *track,
5076 				unsigned int orig_size)
5077 {
5078 	long start, end, pos;
5079 	struct location *l;
5080 	unsigned long caddr, chandle, cwaste;
5081 	unsigned long age = jiffies - track->when;
5082 	depot_stack_handle_t handle = 0;
5083 	unsigned int waste = s->object_size - orig_size;
5084 
5085 #ifdef CONFIG_STACKDEPOT
5086 	handle = READ_ONCE(track->handle);
5087 #endif
5088 	start = -1;
5089 	end = t->count;
5090 
5091 	for ( ; ; ) {
5092 		pos = start + (end - start + 1) / 2;
5093 
5094 		/*
5095 		 * There is nothing at "end". If we end up there
5096 		 * we need to add something to before end.
5097 		 */
5098 		if (pos == end)
5099 			break;
5100 
5101 		l = &t->loc[pos];
5102 		caddr = l->addr;
5103 		chandle = l->handle;
5104 		cwaste = l->waste;
5105 		if ((track->addr == caddr) && (handle == chandle) &&
5106 			(waste == cwaste)) {
5107 
5108 			l->count++;
5109 			if (track->when) {
5110 				l->sum_time += age;
5111 				if (age < l->min_time)
5112 					l->min_time = age;
5113 				if (age > l->max_time)
5114 					l->max_time = age;
5115 
5116 				if (track->pid < l->min_pid)
5117 					l->min_pid = track->pid;
5118 				if (track->pid > l->max_pid)
5119 					l->max_pid = track->pid;
5120 
5121 				cpumask_set_cpu(track->cpu,
5122 						to_cpumask(l->cpus));
5123 			}
5124 			node_set(page_to_nid(virt_to_page(track)), l->nodes);
5125 			return 1;
5126 		}
5127 
5128 		if (track->addr < caddr)
5129 			end = pos;
5130 		else if (track->addr == caddr && handle < chandle)
5131 			end = pos;
5132 		else if (track->addr == caddr && handle == chandle &&
5133 				waste < cwaste)
5134 			end = pos;
5135 		else
5136 			start = pos;
5137 	}
5138 
5139 	/*
5140 	 * Not found. Insert new tracking element.
5141 	 */
5142 	if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
5143 		return 0;
5144 
5145 	l = t->loc + pos;
5146 	if (pos < t->count)
5147 		memmove(l + 1, l,
5148 			(t->count - pos) * sizeof(struct location));
5149 	t->count++;
5150 	l->count = 1;
5151 	l->addr = track->addr;
5152 	l->sum_time = age;
5153 	l->min_time = age;
5154 	l->max_time = age;
5155 	l->min_pid = track->pid;
5156 	l->max_pid = track->pid;
5157 	l->handle = handle;
5158 	l->waste = waste;
5159 	cpumask_clear(to_cpumask(l->cpus));
5160 	cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
5161 	nodes_clear(l->nodes);
5162 	node_set(page_to_nid(virt_to_page(track)), l->nodes);
5163 	return 1;
5164 }
5165 
process_slab(struct loc_track * t,struct kmem_cache * s,struct slab * slab,enum track_item alloc,unsigned long * obj_map)5166 static void process_slab(struct loc_track *t, struct kmem_cache *s,
5167 		struct slab *slab, enum track_item alloc,
5168 		unsigned long *obj_map)
5169 {
5170 	void *addr = slab_address(slab);
5171 	bool is_alloc = (alloc == TRACK_ALLOC);
5172 	void *p;
5173 
5174 	__fill_map(obj_map, s, slab);
5175 
5176 	for_each_object(p, s, addr, slab->objects)
5177 		if (!test_bit(__obj_to_index(s, addr, p), obj_map))
5178 			add_location(t, s, get_track(s, p, alloc),
5179 				     is_alloc ? get_orig_size(s, p) :
5180 						s->object_size);
5181 }
5182 #endif  /* CONFIG_DEBUG_FS   */
5183 #endif	/* CONFIG_SLUB_DEBUG */
5184 
5185 #ifdef CONFIG_SYSFS
5186 enum slab_stat_type {
5187 	SL_ALL,			/* All slabs */
5188 	SL_PARTIAL,		/* Only partially allocated slabs */
5189 	SL_CPU,			/* Only slabs used for cpu caches */
5190 	SL_OBJECTS,		/* Determine allocated objects not slabs */
5191 	SL_TOTAL		/* Determine object capacity not slabs */
5192 };
5193 
5194 #define SO_ALL		(1 << SL_ALL)
5195 #define SO_PARTIAL	(1 << SL_PARTIAL)
5196 #define SO_CPU		(1 << SL_CPU)
5197 #define SO_OBJECTS	(1 << SL_OBJECTS)
5198 #define SO_TOTAL	(1 << SL_TOTAL)
5199 
show_slab_objects(struct kmem_cache * s,char * buf,unsigned long flags)5200 static ssize_t show_slab_objects(struct kmem_cache *s,
5201 				 char *buf, unsigned long flags)
5202 {
5203 	unsigned long total = 0;
5204 	int node;
5205 	int x;
5206 	unsigned long *nodes;
5207 	int len = 0;
5208 
5209 	nodes = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL);
5210 	if (!nodes)
5211 		return -ENOMEM;
5212 
5213 	if (flags & SO_CPU) {
5214 		int cpu;
5215 
5216 		for_each_possible_cpu(cpu) {
5217 			struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
5218 							       cpu);
5219 			int node;
5220 			struct slab *slab;
5221 
5222 			slab = READ_ONCE(c->slab);
5223 			if (!slab)
5224 				continue;
5225 
5226 			node = slab_nid(slab);
5227 			if (flags & SO_TOTAL)
5228 				x = slab->objects;
5229 			else if (flags & SO_OBJECTS)
5230 				x = slab->inuse;
5231 			else
5232 				x = 1;
5233 
5234 			total += x;
5235 			nodes[node] += x;
5236 
5237 #ifdef CONFIG_SLUB_CPU_PARTIAL
5238 			slab = slub_percpu_partial_read_once(c);
5239 			if (slab) {
5240 				node = slab_nid(slab);
5241 				if (flags & SO_TOTAL)
5242 					WARN_ON_ONCE(1);
5243 				else if (flags & SO_OBJECTS)
5244 					WARN_ON_ONCE(1);
5245 				else
5246 					x = slab->slabs;
5247 				total += x;
5248 				nodes[node] += x;
5249 			}
5250 #endif
5251 		}
5252 	}
5253 
5254 	/*
5255 	 * It is impossible to take "mem_hotplug_lock" here with "kernfs_mutex"
5256 	 * already held which will conflict with an existing lock order:
5257 	 *
5258 	 * mem_hotplug_lock->slab_mutex->kernfs_mutex
5259 	 *
5260 	 * We don't really need mem_hotplug_lock (to hold off
5261 	 * slab_mem_going_offline_callback) here because slab's memory hot
5262 	 * unplug code doesn't destroy the kmem_cache->node[] data.
5263 	 */
5264 
5265 #ifdef CONFIG_SLUB_DEBUG
5266 	if (flags & SO_ALL) {
5267 		struct kmem_cache_node *n;
5268 
5269 		for_each_kmem_cache_node(s, node, n) {
5270 
5271 			if (flags & SO_TOTAL)
5272 				x = atomic_long_read(&n->total_objects);
5273 			else if (flags & SO_OBJECTS)
5274 				x = atomic_long_read(&n->total_objects) -
5275 					count_partial(n, count_free);
5276 			else
5277 				x = atomic_long_read(&n->nr_slabs);
5278 			total += x;
5279 			nodes[node] += x;
5280 		}
5281 
5282 	} else
5283 #endif
5284 	if (flags & SO_PARTIAL) {
5285 		struct kmem_cache_node *n;
5286 
5287 		for_each_kmem_cache_node(s, node, n) {
5288 			if (flags & SO_TOTAL)
5289 				x = count_partial(n, count_total);
5290 			else if (flags & SO_OBJECTS)
5291 				x = count_partial(n, count_inuse);
5292 			else
5293 				x = n->nr_partial;
5294 			total += x;
5295 			nodes[node] += x;
5296 		}
5297 	}
5298 
5299 	len += sysfs_emit_at(buf, len, "%lu", total);
5300 #ifdef CONFIG_NUMA
5301 	for (node = 0; node < nr_node_ids; node++) {
5302 		if (nodes[node])
5303 			len += sysfs_emit_at(buf, len, " N%d=%lu",
5304 					     node, nodes[node]);
5305 	}
5306 #endif
5307 	len += sysfs_emit_at(buf, len, "\n");
5308 	kfree(nodes);
5309 
5310 	return len;
5311 }
5312 
5313 #define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
5314 #define to_slab(n) container_of(n, struct kmem_cache, kobj)
5315 
5316 struct slab_attribute {
5317 	struct attribute attr;
5318 	ssize_t (*show)(struct kmem_cache *s, char *buf);
5319 	ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
5320 };
5321 
5322 #define SLAB_ATTR_RO(_name) \
5323 	static struct slab_attribute _name##_attr = __ATTR_RO_MODE(_name, 0400)
5324 
5325 #define SLAB_ATTR(_name) \
5326 	static struct slab_attribute _name##_attr = __ATTR_RW_MODE(_name, 0600)
5327 
slab_size_show(struct kmem_cache * s,char * buf)5328 static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
5329 {
5330 	return sysfs_emit(buf, "%u\n", s->size);
5331 }
5332 SLAB_ATTR_RO(slab_size);
5333 
align_show(struct kmem_cache * s,char * buf)5334 static ssize_t align_show(struct kmem_cache *s, char *buf)
5335 {
5336 	return sysfs_emit(buf, "%u\n", s->align);
5337 }
5338 SLAB_ATTR_RO(align);
5339 
object_size_show(struct kmem_cache * s,char * buf)5340 static ssize_t object_size_show(struct kmem_cache *s, char *buf)
5341 {
5342 	return sysfs_emit(buf, "%u\n", s->object_size);
5343 }
5344 SLAB_ATTR_RO(object_size);
5345 
objs_per_slab_show(struct kmem_cache * s,char * buf)5346 static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
5347 {
5348 	return sysfs_emit(buf, "%u\n", oo_objects(s->oo));
5349 }
5350 SLAB_ATTR_RO(objs_per_slab);
5351 
order_show(struct kmem_cache * s,char * buf)5352 static ssize_t order_show(struct kmem_cache *s, char *buf)
5353 {
5354 	return sysfs_emit(buf, "%u\n", oo_order(s->oo));
5355 }
5356 SLAB_ATTR_RO(order);
5357 
min_partial_show(struct kmem_cache * s,char * buf)5358 static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
5359 {
5360 	return sysfs_emit(buf, "%lu\n", s->min_partial);
5361 }
5362 
min_partial_store(struct kmem_cache * s,const char * buf,size_t length)5363 static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
5364 				 size_t length)
5365 {
5366 	unsigned long min;
5367 	int err;
5368 
5369 	err = kstrtoul(buf, 10, &min);
5370 	if (err)
5371 		return err;
5372 
5373 	s->min_partial = min;
5374 	return length;
5375 }
5376 SLAB_ATTR(min_partial);
5377 
cpu_partial_show(struct kmem_cache * s,char * buf)5378 static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
5379 {
5380 	unsigned int nr_partial = 0;
5381 #ifdef CONFIG_SLUB_CPU_PARTIAL
5382 	nr_partial = s->cpu_partial;
5383 #endif
5384 
5385 	return sysfs_emit(buf, "%u\n", nr_partial);
5386 }
5387 
cpu_partial_store(struct kmem_cache * s,const char * buf,size_t length)5388 static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
5389 				 size_t length)
5390 {
5391 	unsigned int objects;
5392 	int err;
5393 
5394 	err = kstrtouint(buf, 10, &objects);
5395 	if (err)
5396 		return err;
5397 	if (objects && !kmem_cache_has_cpu_partial(s))
5398 		return -EINVAL;
5399 
5400 	slub_set_cpu_partial(s, objects);
5401 	flush_all(s);
5402 	return length;
5403 }
5404 SLAB_ATTR(cpu_partial);
5405 
ctor_show(struct kmem_cache * s,char * buf)5406 static ssize_t ctor_show(struct kmem_cache *s, char *buf)
5407 {
5408 	if (!s->ctor)
5409 		return 0;
5410 	return sysfs_emit(buf, "%pS\n", s->ctor);
5411 }
5412 SLAB_ATTR_RO(ctor);
5413 
aliases_show(struct kmem_cache * s,char * buf)5414 static ssize_t aliases_show(struct kmem_cache *s, char *buf)
5415 {
5416 	return sysfs_emit(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1);
5417 }
5418 SLAB_ATTR_RO(aliases);
5419 
partial_show(struct kmem_cache * s,char * buf)5420 static ssize_t partial_show(struct kmem_cache *s, char *buf)
5421 {
5422 	return show_slab_objects(s, buf, SO_PARTIAL);
5423 }
5424 SLAB_ATTR_RO(partial);
5425 
cpu_slabs_show(struct kmem_cache * s,char * buf)5426 static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
5427 {
5428 	return show_slab_objects(s, buf, SO_CPU);
5429 }
5430 SLAB_ATTR_RO(cpu_slabs);
5431 
objects_show(struct kmem_cache * s,char * buf)5432 static ssize_t objects_show(struct kmem_cache *s, char *buf)
5433 {
5434 	return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS);
5435 }
5436 SLAB_ATTR_RO(objects);
5437 
objects_partial_show(struct kmem_cache * s,char * buf)5438 static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
5439 {
5440 	return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS);
5441 }
5442 SLAB_ATTR_RO(objects_partial);
5443 
slabs_cpu_partial_show(struct kmem_cache * s,char * buf)5444 static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
5445 {
5446 	int objects = 0;
5447 	int slabs = 0;
5448 	int cpu __maybe_unused;
5449 	int len = 0;
5450 
5451 #ifdef CONFIG_SLUB_CPU_PARTIAL
5452 	for_each_online_cpu(cpu) {
5453 		struct slab *slab;
5454 
5455 		slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
5456 
5457 		if (slab)
5458 			slabs += slab->slabs;
5459 	}
5460 #endif
5461 
5462 	/* Approximate half-full slabs, see slub_set_cpu_partial() */
5463 	objects = (slabs * oo_objects(s->oo)) / 2;
5464 	len += sysfs_emit_at(buf, len, "%d(%d)", objects, slabs);
5465 
5466 #if defined(CONFIG_SLUB_CPU_PARTIAL) && defined(CONFIG_SMP)
5467 	for_each_online_cpu(cpu) {
5468 		struct slab *slab;
5469 
5470 		slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
5471 		if (slab) {
5472 			slabs = READ_ONCE(slab->slabs);
5473 			objects = (slabs * oo_objects(s->oo)) / 2;
5474 			len += sysfs_emit_at(buf, len, " C%d=%d(%d)",
5475 					     cpu, objects, slabs);
5476 		}
5477 	}
5478 #endif
5479 	len += sysfs_emit_at(buf, len, "\n");
5480 
5481 	return len;
5482 }
5483 SLAB_ATTR_RO(slabs_cpu_partial);
5484 
reclaim_account_show(struct kmem_cache * s,char * buf)5485 static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
5486 {
5487 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
5488 }
5489 SLAB_ATTR_RO(reclaim_account);
5490 
hwcache_align_show(struct kmem_cache * s,char * buf)5491 static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
5492 {
5493 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
5494 }
5495 SLAB_ATTR_RO(hwcache_align);
5496 
5497 #ifdef CONFIG_ZONE_DMA
cache_dma_show(struct kmem_cache * s,char * buf)5498 static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
5499 {
5500 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
5501 }
5502 SLAB_ATTR_RO(cache_dma);
5503 #endif
5504 
usersize_show(struct kmem_cache * s,char * buf)5505 static ssize_t usersize_show(struct kmem_cache *s, char *buf)
5506 {
5507 	return sysfs_emit(buf, "%u\n", s->usersize);
5508 }
5509 SLAB_ATTR_RO(usersize);
5510 
destroy_by_rcu_show(struct kmem_cache * s,char * buf)5511 static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
5512 {
5513 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU));
5514 }
5515 SLAB_ATTR_RO(destroy_by_rcu);
5516 
5517 #ifdef CONFIG_SLUB_DEBUG
slabs_show(struct kmem_cache * s,char * buf)5518 static ssize_t slabs_show(struct kmem_cache *s, char *buf)
5519 {
5520 	return show_slab_objects(s, buf, SO_ALL);
5521 }
5522 SLAB_ATTR_RO(slabs);
5523 
total_objects_show(struct kmem_cache * s,char * buf)5524 static ssize_t total_objects_show(struct kmem_cache *s, char *buf)
5525 {
5526 	return show_slab_objects(s, buf, SO_ALL|SO_TOTAL);
5527 }
5528 SLAB_ATTR_RO(total_objects);
5529 
sanity_checks_show(struct kmem_cache * s,char * buf)5530 static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
5531 {
5532 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS));
5533 }
5534 SLAB_ATTR_RO(sanity_checks);
5535 
trace_show(struct kmem_cache * s,char * buf)5536 static ssize_t trace_show(struct kmem_cache *s, char *buf)
5537 {
5538 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TRACE));
5539 }
5540 SLAB_ATTR_RO(trace);
5541 
red_zone_show(struct kmem_cache * s,char * buf)5542 static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
5543 {
5544 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
5545 }
5546 
5547 SLAB_ATTR_RO(red_zone);
5548 
poison_show(struct kmem_cache * s,char * buf)5549 static ssize_t poison_show(struct kmem_cache *s, char *buf)
5550 {
5551 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_POISON));
5552 }
5553 
5554 SLAB_ATTR_RO(poison);
5555 
store_user_show(struct kmem_cache * s,char * buf)5556 static ssize_t store_user_show(struct kmem_cache *s, char *buf)
5557 {
5558 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
5559 }
5560 
5561 SLAB_ATTR_RO(store_user);
5562 
validate_show(struct kmem_cache * s,char * buf)5563 static ssize_t validate_show(struct kmem_cache *s, char *buf)
5564 {
5565 	return 0;
5566 }
5567 
validate_store(struct kmem_cache * s,const char * buf,size_t length)5568 static ssize_t validate_store(struct kmem_cache *s,
5569 			const char *buf, size_t length)
5570 {
5571 	int ret = -EINVAL;
5572 
5573 	if (buf[0] == '1' && kmem_cache_debug(s)) {
5574 		ret = validate_slab_cache(s);
5575 		if (ret >= 0)
5576 			ret = length;
5577 	}
5578 	return ret;
5579 }
5580 SLAB_ATTR(validate);
5581 
5582 #endif /* CONFIG_SLUB_DEBUG */
5583 
5584 #ifdef CONFIG_FAILSLAB
failslab_show(struct kmem_cache * s,char * buf)5585 static ssize_t failslab_show(struct kmem_cache *s, char *buf)
5586 {
5587 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
5588 }
5589 SLAB_ATTR_RO(failslab);
5590 #endif
5591 
shrink_show(struct kmem_cache * s,char * buf)5592 static ssize_t shrink_show(struct kmem_cache *s, char *buf)
5593 {
5594 	return 0;
5595 }
5596 
shrink_store(struct kmem_cache * s,const char * buf,size_t length)5597 static ssize_t shrink_store(struct kmem_cache *s,
5598 			const char *buf, size_t length)
5599 {
5600 	if (buf[0] == '1')
5601 		kmem_cache_shrink(s);
5602 	else
5603 		return -EINVAL;
5604 	return length;
5605 }
5606 SLAB_ATTR(shrink);
5607 
5608 #ifdef CONFIG_NUMA
remote_node_defrag_ratio_show(struct kmem_cache * s,char * buf)5609 static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
5610 {
5611 	return sysfs_emit(buf, "%u\n", s->remote_node_defrag_ratio / 10);
5612 }
5613 
remote_node_defrag_ratio_store(struct kmem_cache * s,const char * buf,size_t length)5614 static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
5615 				const char *buf, size_t length)
5616 {
5617 	unsigned int ratio;
5618 	int err;
5619 
5620 	err = kstrtouint(buf, 10, &ratio);
5621 	if (err)
5622 		return err;
5623 	if (ratio > 100)
5624 		return -ERANGE;
5625 
5626 	s->remote_node_defrag_ratio = ratio * 10;
5627 
5628 	return length;
5629 }
5630 SLAB_ATTR(remote_node_defrag_ratio);
5631 #endif
5632 
5633 #ifdef CONFIG_SLUB_STATS
show_stat(struct kmem_cache * s,char * buf,enum stat_item si)5634 static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
5635 {
5636 	unsigned long sum  = 0;
5637 	int cpu;
5638 	int len = 0;
5639 	int *data = kmalloc_array(nr_cpu_ids, sizeof(int), GFP_KERNEL);
5640 
5641 	if (!data)
5642 		return -ENOMEM;
5643 
5644 	for_each_online_cpu(cpu) {
5645 		unsigned x = per_cpu_ptr(s->cpu_slab, cpu)->stat[si];
5646 
5647 		data[cpu] = x;
5648 		sum += x;
5649 	}
5650 
5651 	len += sysfs_emit_at(buf, len, "%lu", sum);
5652 
5653 #ifdef CONFIG_SMP
5654 	for_each_online_cpu(cpu) {
5655 		if (data[cpu])
5656 			len += sysfs_emit_at(buf, len, " C%d=%u",
5657 					     cpu, data[cpu]);
5658 	}
5659 #endif
5660 	kfree(data);
5661 	len += sysfs_emit_at(buf, len, "\n");
5662 
5663 	return len;
5664 }
5665 
clear_stat(struct kmem_cache * s,enum stat_item si)5666 static void clear_stat(struct kmem_cache *s, enum stat_item si)
5667 {
5668 	int cpu;
5669 
5670 	for_each_online_cpu(cpu)
5671 		per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0;
5672 }
5673 
5674 #define STAT_ATTR(si, text) 					\
5675 static ssize_t text##_show(struct kmem_cache *s, char *buf)	\
5676 {								\
5677 	return show_stat(s, buf, si);				\
5678 }								\
5679 static ssize_t text##_store(struct kmem_cache *s,		\
5680 				const char *buf, size_t length)	\
5681 {								\
5682 	if (buf[0] != '0')					\
5683 		return -EINVAL;					\
5684 	clear_stat(s, si);					\
5685 	return length;						\
5686 }								\
5687 SLAB_ATTR(text);						\
5688 
5689 STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
5690 STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);
5691 STAT_ATTR(FREE_FASTPATH, free_fastpath);
5692 STAT_ATTR(FREE_SLOWPATH, free_slowpath);
5693 STAT_ATTR(FREE_FROZEN, free_frozen);
5694 STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);
5695 STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
5696 STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
5697 STAT_ATTR(ALLOC_SLAB, alloc_slab);
5698 STAT_ATTR(ALLOC_REFILL, alloc_refill);
5699 STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
5700 STAT_ATTR(FREE_SLAB, free_slab);
5701 STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
5702 STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
5703 STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
5704 STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
5705 STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
5706 STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
5707 STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
5708 STAT_ATTR(ORDER_FALLBACK, order_fallback);
5709 STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
5710 STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
5711 STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
5712 STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
5713 STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
5714 STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
5715 #endif	/* CONFIG_SLUB_STATS */
5716 
5717 #ifdef CONFIG_KFENCE
skip_kfence_show(struct kmem_cache * s,char * buf)5718 static ssize_t skip_kfence_show(struct kmem_cache *s, char *buf)
5719 {
5720 	return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_SKIP_KFENCE));
5721 }
5722 
skip_kfence_store(struct kmem_cache * s,const char * buf,size_t length)5723 static ssize_t skip_kfence_store(struct kmem_cache *s,
5724 			const char *buf, size_t length)
5725 {
5726 	int ret = length;
5727 
5728 	if (buf[0] == '0')
5729 		s->flags &= ~SLAB_SKIP_KFENCE;
5730 	else if (buf[0] == '1')
5731 		s->flags |= SLAB_SKIP_KFENCE;
5732 	else
5733 		ret = -EINVAL;
5734 
5735 	return ret;
5736 }
5737 SLAB_ATTR(skip_kfence);
5738 #endif
5739 
5740 static struct attribute *slab_attrs[] = {
5741 	&slab_size_attr.attr,
5742 	&object_size_attr.attr,
5743 	&objs_per_slab_attr.attr,
5744 	&order_attr.attr,
5745 	&min_partial_attr.attr,
5746 	&cpu_partial_attr.attr,
5747 	&objects_attr.attr,
5748 	&objects_partial_attr.attr,
5749 	&partial_attr.attr,
5750 	&cpu_slabs_attr.attr,
5751 	&ctor_attr.attr,
5752 	&aliases_attr.attr,
5753 	&align_attr.attr,
5754 	&hwcache_align_attr.attr,
5755 	&reclaim_account_attr.attr,
5756 	&destroy_by_rcu_attr.attr,
5757 	&shrink_attr.attr,
5758 	&slabs_cpu_partial_attr.attr,
5759 #ifdef CONFIG_SLUB_DEBUG
5760 	&total_objects_attr.attr,
5761 	&slabs_attr.attr,
5762 	&sanity_checks_attr.attr,
5763 	&trace_attr.attr,
5764 	&red_zone_attr.attr,
5765 	&poison_attr.attr,
5766 	&store_user_attr.attr,
5767 	&validate_attr.attr,
5768 #endif
5769 #ifdef CONFIG_ZONE_DMA
5770 	&cache_dma_attr.attr,
5771 #endif
5772 #ifdef CONFIG_NUMA
5773 	&remote_node_defrag_ratio_attr.attr,
5774 #endif
5775 #ifdef CONFIG_SLUB_STATS
5776 	&alloc_fastpath_attr.attr,
5777 	&alloc_slowpath_attr.attr,
5778 	&free_fastpath_attr.attr,
5779 	&free_slowpath_attr.attr,
5780 	&free_frozen_attr.attr,
5781 	&free_add_partial_attr.attr,
5782 	&free_remove_partial_attr.attr,
5783 	&alloc_from_partial_attr.attr,
5784 	&alloc_slab_attr.attr,
5785 	&alloc_refill_attr.attr,
5786 	&alloc_node_mismatch_attr.attr,
5787 	&free_slab_attr.attr,
5788 	&cpuslab_flush_attr.attr,
5789 	&deactivate_full_attr.attr,
5790 	&deactivate_empty_attr.attr,
5791 	&deactivate_to_head_attr.attr,
5792 	&deactivate_to_tail_attr.attr,
5793 	&deactivate_remote_frees_attr.attr,
5794 	&deactivate_bypass_attr.attr,
5795 	&order_fallback_attr.attr,
5796 	&cmpxchg_double_fail_attr.attr,
5797 	&cmpxchg_double_cpu_fail_attr.attr,
5798 	&cpu_partial_alloc_attr.attr,
5799 	&cpu_partial_free_attr.attr,
5800 	&cpu_partial_node_attr.attr,
5801 	&cpu_partial_drain_attr.attr,
5802 #endif
5803 #ifdef CONFIG_FAILSLAB
5804 	&failslab_attr.attr,
5805 #endif
5806 	&usersize_attr.attr,
5807 #ifdef CONFIG_KFENCE
5808 	&skip_kfence_attr.attr,
5809 #endif
5810 
5811 	NULL
5812 };
5813 
5814 static const struct attribute_group slab_attr_group = {
5815 	.attrs = slab_attrs,
5816 };
5817 
slab_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)5818 static ssize_t slab_attr_show(struct kobject *kobj,
5819 				struct attribute *attr,
5820 				char *buf)
5821 {
5822 	struct slab_attribute *attribute;
5823 	struct kmem_cache *s;
5824 
5825 	attribute = to_slab_attr(attr);
5826 	s = to_slab(kobj);
5827 
5828 	if (!attribute->show)
5829 		return -EIO;
5830 
5831 	return attribute->show(s, buf);
5832 }
5833 
slab_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t len)5834 static ssize_t slab_attr_store(struct kobject *kobj,
5835 				struct attribute *attr,
5836 				const char *buf, size_t len)
5837 {
5838 	struct slab_attribute *attribute;
5839 	struct kmem_cache *s;
5840 
5841 	attribute = to_slab_attr(attr);
5842 	s = to_slab(kobj);
5843 
5844 	if (!attribute->store)
5845 		return -EIO;
5846 
5847 	return attribute->store(s, buf, len);
5848 }
5849 
kmem_cache_release(struct kobject * k)5850 static void kmem_cache_release(struct kobject *k)
5851 {
5852 	slab_kmem_cache_release(to_slab(k));
5853 }
5854 
5855 static const struct sysfs_ops slab_sysfs_ops = {
5856 	.show = slab_attr_show,
5857 	.store = slab_attr_store,
5858 };
5859 
5860 static struct kobj_type slab_ktype = {
5861 	.sysfs_ops = &slab_sysfs_ops,
5862 	.release = kmem_cache_release,
5863 };
5864 
5865 static struct kset *slab_kset;
5866 
cache_kset(struct kmem_cache * s)5867 static inline struct kset *cache_kset(struct kmem_cache *s)
5868 {
5869 	return slab_kset;
5870 }
5871 
5872 #define ID_STR_LENGTH 32
5873 
5874 /* Create a unique string id for a slab cache:
5875  *
5876  * Format	:[flags-]size
5877  */
create_unique_id(struct kmem_cache * s)5878 static char *create_unique_id(struct kmem_cache *s)
5879 {
5880 	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
5881 	char *p = name;
5882 
5883 	if (!name)
5884 		return ERR_PTR(-ENOMEM);
5885 
5886 	*p++ = ':';
5887 	/*
5888 	 * First flags affecting slabcache operations. We will only
5889 	 * get here for aliasable slabs so we do not need to support
5890 	 * too many flags. The flags here must cover all flags that
5891 	 * are matched during merging to guarantee that the id is
5892 	 * unique.
5893 	 */
5894 	if (s->flags & SLAB_CACHE_DMA)
5895 		*p++ = 'd';
5896 	if (s->flags & SLAB_CACHE_DMA32)
5897 		*p++ = 'D';
5898 	if (s->flags & SLAB_RECLAIM_ACCOUNT)
5899 		*p++ = 'a';
5900 	if (s->flags & SLAB_CONSISTENCY_CHECKS)
5901 		*p++ = 'F';
5902 	if (s->flags & SLAB_ACCOUNT)
5903 		*p++ = 'A';
5904 	if (p != name + 1)
5905 		*p++ = '-';
5906 	p += snprintf(p, ID_STR_LENGTH - (p - name), "%07u", s->size);
5907 
5908 	if (WARN_ON(p > name + ID_STR_LENGTH - 1)) {
5909 		kfree(name);
5910 		return ERR_PTR(-EINVAL);
5911 	}
5912 	kmsan_unpoison_memory(name, p - name);
5913 	return name;
5914 }
5915 
sysfs_slab_add(struct kmem_cache * s)5916 static int sysfs_slab_add(struct kmem_cache *s)
5917 {
5918 	int err;
5919 	const char *name;
5920 	struct kset *kset = cache_kset(s);
5921 	int unmergeable = slab_unmergeable(s);
5922 
5923 	if (!kset) {
5924 		kobject_init(&s->kobj, &slab_ktype);
5925 		return 0;
5926 	}
5927 
5928 	if (!unmergeable && disable_higher_order_debug &&
5929 			(slub_debug & DEBUG_METADATA_FLAGS))
5930 		unmergeable = 1;
5931 
5932 	if (unmergeable) {
5933 		/*
5934 		 * Slabcache can never be merged so we can use the name proper.
5935 		 * This is typically the case for debug situations. In that
5936 		 * case we can catch duplicate names easily.
5937 		 */
5938 		sysfs_remove_link(&slab_kset->kobj, s->name);
5939 		name = s->name;
5940 	} else {
5941 		/*
5942 		 * Create a unique name for the slab as a target
5943 		 * for the symlinks.
5944 		 */
5945 		name = create_unique_id(s);
5946 		if (IS_ERR(name))
5947 			return PTR_ERR(name);
5948 	}
5949 
5950 	s->kobj.kset = kset;
5951 	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
5952 	if (err)
5953 		goto out;
5954 
5955 	err = sysfs_create_group(&s->kobj, &slab_attr_group);
5956 	if (err)
5957 		goto out_del_kobj;
5958 
5959 	if (!unmergeable) {
5960 		/* Setup first alias */
5961 		sysfs_slab_alias(s, s->name);
5962 	}
5963 out:
5964 	if (!unmergeable)
5965 		kfree(name);
5966 	return err;
5967 out_del_kobj:
5968 	kobject_del(&s->kobj);
5969 	goto out;
5970 }
5971 
sysfs_slab_unlink(struct kmem_cache * s)5972 void sysfs_slab_unlink(struct kmem_cache *s)
5973 {
5974 	if (slab_state >= FULL)
5975 		kobject_del(&s->kobj);
5976 }
5977 
sysfs_slab_release(struct kmem_cache * s)5978 void sysfs_slab_release(struct kmem_cache *s)
5979 {
5980 	if (slab_state >= FULL)
5981 		kobject_put(&s->kobj);
5982 }
5983 
5984 /*
5985  * Need to buffer aliases during bootup until sysfs becomes
5986  * available lest we lose that information.
5987  */
5988 struct saved_alias {
5989 	struct kmem_cache *s;
5990 	const char *name;
5991 	struct saved_alias *next;
5992 };
5993 
5994 static struct saved_alias *alias_list;
5995 
sysfs_slab_alias(struct kmem_cache * s,const char * name)5996 static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
5997 {
5998 	struct saved_alias *al;
5999 
6000 	if (slab_state == FULL) {
6001 		/*
6002 		 * If we have a leftover link then remove it.
6003 		 */
6004 		sysfs_remove_link(&slab_kset->kobj, name);
6005 		return sysfs_create_link(&slab_kset->kobj, &s->kobj, name);
6006 	}
6007 
6008 	al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
6009 	if (!al)
6010 		return -ENOMEM;
6011 
6012 	al->s = s;
6013 	al->name = name;
6014 	al->next = alias_list;
6015 	alias_list = al;
6016 	kmsan_unpoison_memory(al, sizeof(*al));
6017 	return 0;
6018 }
6019 
slab_sysfs_init(void)6020 static int __init slab_sysfs_init(void)
6021 {
6022 	struct kmem_cache *s;
6023 	int err;
6024 
6025 	mutex_lock(&slab_mutex);
6026 
6027 	slab_kset = kset_create_and_add("slab", NULL, kernel_kobj);
6028 	if (!slab_kset) {
6029 		mutex_unlock(&slab_mutex);
6030 		pr_err("Cannot register slab subsystem.\n");
6031 		return -ENOSYS;
6032 	}
6033 
6034 	slab_state = FULL;
6035 
6036 	list_for_each_entry(s, &slab_caches, list) {
6037 		err = sysfs_slab_add(s);
6038 		if (err)
6039 			pr_err("SLUB: Unable to add boot slab %s to sysfs\n",
6040 			       s->name);
6041 	}
6042 
6043 	while (alias_list) {
6044 		struct saved_alias *al = alias_list;
6045 
6046 		alias_list = alias_list->next;
6047 		err = sysfs_slab_alias(al->s, al->name);
6048 		if (err)
6049 			pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n",
6050 			       al->name);
6051 		kfree(al);
6052 	}
6053 
6054 	mutex_unlock(&slab_mutex);
6055 	return 0;
6056 }
6057 
6058 __initcall(slab_sysfs_init);
6059 #endif /* CONFIG_SYSFS */
6060 
6061 #if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)
slab_debugfs_show(struct seq_file * seq,void * v)6062 static int slab_debugfs_show(struct seq_file *seq, void *v)
6063 {
6064 	struct loc_track *t = seq->private;
6065 	struct location *l;
6066 	unsigned long idx;
6067 
6068 	idx = (unsigned long) t->idx;
6069 	if (idx < t->count) {
6070 		l = &t->loc[idx];
6071 
6072 		seq_printf(seq, "%7ld ", l->count);
6073 
6074 		if (l->addr)
6075 			seq_printf(seq, "%pS", (void *)l->addr);
6076 		else
6077 			seq_puts(seq, "<not-available>");
6078 
6079 		if (l->waste)
6080 			seq_printf(seq, " waste=%lu/%lu",
6081 				l->count * l->waste, l->waste);
6082 
6083 		if (l->sum_time != l->min_time) {
6084 			seq_printf(seq, " age=%ld/%llu/%ld",
6085 				l->min_time, div_u64(l->sum_time, l->count),
6086 				l->max_time);
6087 		} else
6088 			seq_printf(seq, " age=%ld", l->min_time);
6089 
6090 		if (l->min_pid != l->max_pid)
6091 			seq_printf(seq, " pid=%ld-%ld", l->min_pid, l->max_pid);
6092 		else
6093 			seq_printf(seq, " pid=%ld",
6094 				l->min_pid);
6095 
6096 		if (num_online_cpus() > 1 && !cpumask_empty(to_cpumask(l->cpus)))
6097 			seq_printf(seq, " cpus=%*pbl",
6098 				 cpumask_pr_args(to_cpumask(l->cpus)));
6099 
6100 		if (nr_online_nodes > 1 && !nodes_empty(l->nodes))
6101 			seq_printf(seq, " nodes=%*pbl",
6102 				 nodemask_pr_args(&l->nodes));
6103 
6104 #ifdef CONFIG_STACKDEPOT
6105 		{
6106 			depot_stack_handle_t handle;
6107 			unsigned long *entries;
6108 			unsigned int nr_entries, j;
6109 
6110 			handle = READ_ONCE(l->handle);
6111 			if (handle) {
6112 				nr_entries = stack_depot_fetch(handle, &entries);
6113 				seq_puts(seq, "\n");
6114 				for (j = 0; j < nr_entries; j++)
6115 					seq_printf(seq, "        %pS\n", (void *)entries[j]);
6116 			}
6117 		}
6118 #endif
6119 		seq_puts(seq, "\n");
6120 	}
6121 
6122 	if (!idx && !t->count)
6123 		seq_puts(seq, "No data\n");
6124 
6125 	return 0;
6126 }
6127 
slab_debugfs_stop(struct seq_file * seq,void * v)6128 static void slab_debugfs_stop(struct seq_file *seq, void *v)
6129 {
6130 }
6131 
slab_debugfs_next(struct seq_file * seq,void * v,loff_t * ppos)6132 static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos)
6133 {
6134 	struct loc_track *t = seq->private;
6135 
6136 	t->idx = ++(*ppos);
6137 	if (*ppos <= t->count)
6138 		return ppos;
6139 
6140 	return NULL;
6141 }
6142 
cmp_loc_by_count(const void * a,const void * b,const void * data)6143 static int cmp_loc_by_count(const void *a, const void *b, const void *data)
6144 {
6145 	struct location *loc1 = (struct location *)a;
6146 	struct location *loc2 = (struct location *)b;
6147 
6148 	if (loc1->count > loc2->count)
6149 		return -1;
6150 	else
6151 		return 1;
6152 }
6153 
slab_debugfs_start(struct seq_file * seq,loff_t * ppos)6154 static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
6155 {
6156 	struct loc_track *t = seq->private;
6157 
6158 	t->idx = *ppos;
6159 	return ppos;
6160 }
6161 
6162 static const struct seq_operations slab_debugfs_sops = {
6163 	.start  = slab_debugfs_start,
6164 	.next   = slab_debugfs_next,
6165 	.stop   = slab_debugfs_stop,
6166 	.show   = slab_debugfs_show,
6167 };
6168 
slab_debug_trace_open(struct inode * inode,struct file * filep)6169 static int slab_debug_trace_open(struct inode *inode, struct file *filep)
6170 {
6171 
6172 	struct kmem_cache_node *n;
6173 	enum track_item alloc;
6174 	int node;
6175 	struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops,
6176 						sizeof(struct loc_track));
6177 	struct kmem_cache *s = file_inode(filep)->i_private;
6178 	unsigned long *obj_map;
6179 
6180 	if (!t)
6181 		return -ENOMEM;
6182 
6183 	obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
6184 	if (!obj_map) {
6185 		seq_release_private(inode, filep);
6186 		return -ENOMEM;
6187 	}
6188 
6189 	if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0)
6190 		alloc = TRACK_ALLOC;
6191 	else
6192 		alloc = TRACK_FREE;
6193 
6194 	if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) {
6195 		bitmap_free(obj_map);
6196 		seq_release_private(inode, filep);
6197 		return -ENOMEM;
6198 	}
6199 
6200 	for_each_kmem_cache_node(s, node, n) {
6201 		unsigned long flags;
6202 		struct slab *slab;
6203 
6204 		if (!atomic_long_read(&n->nr_slabs))
6205 			continue;
6206 
6207 		spin_lock_irqsave(&n->list_lock, flags);
6208 		list_for_each_entry(slab, &n->partial, slab_list)
6209 			process_slab(t, s, slab, alloc, obj_map);
6210 		list_for_each_entry(slab, &n->full, slab_list)
6211 			process_slab(t, s, slab, alloc, obj_map);
6212 		spin_unlock_irqrestore(&n->list_lock, flags);
6213 	}
6214 
6215 	/* Sort locations by count */
6216 	sort_r(t->loc, t->count, sizeof(struct location),
6217 		cmp_loc_by_count, NULL, NULL);
6218 
6219 	bitmap_free(obj_map);
6220 	return 0;
6221 }
6222 
slab_debug_trace_release(struct inode * inode,struct file * file)6223 static int slab_debug_trace_release(struct inode *inode, struct file *file)
6224 {
6225 	struct seq_file *seq = file->private_data;
6226 	struct loc_track *t = seq->private;
6227 
6228 	free_loc_track(t);
6229 	return seq_release_private(inode, file);
6230 }
6231 
6232 static const struct file_operations slab_debugfs_fops = {
6233 	.open    = slab_debug_trace_open,
6234 	.read    = seq_read,
6235 	.llseek  = seq_lseek,
6236 	.release = slab_debug_trace_release,
6237 };
6238 
debugfs_slab_add(struct kmem_cache * s)6239 static void debugfs_slab_add(struct kmem_cache *s)
6240 {
6241 	struct dentry *slab_cache_dir;
6242 
6243 	if (unlikely(!slab_debugfs_root))
6244 		return;
6245 
6246 	slab_cache_dir = debugfs_create_dir(s->name, slab_debugfs_root);
6247 
6248 	debugfs_create_file("alloc_traces", 0400,
6249 		slab_cache_dir, s, &slab_debugfs_fops);
6250 
6251 	debugfs_create_file("free_traces", 0400,
6252 		slab_cache_dir, s, &slab_debugfs_fops);
6253 }
6254 
debugfs_slab_release(struct kmem_cache * s)6255 void debugfs_slab_release(struct kmem_cache *s)
6256 {
6257 	debugfs_remove_recursive(debugfs_lookup(s->name, slab_debugfs_root));
6258 }
6259 
slab_debugfs_init(void)6260 static int __init slab_debugfs_init(void)
6261 {
6262 	struct kmem_cache *s;
6263 
6264 	slab_debugfs_root = debugfs_create_dir("slab", NULL);
6265 
6266 	list_for_each_entry(s, &slab_caches, list)
6267 		if (s->flags & SLAB_STORE_USER)
6268 			debugfs_slab_add(s);
6269 
6270 	return 0;
6271 
6272 }
6273 __initcall(slab_debugfs_init);
6274 #endif
6275 /*
6276  * The /proc/slabinfo ABI
6277  */
6278 #ifdef CONFIG_SLUB_DEBUG
get_slabinfo(struct kmem_cache * s,struct slabinfo * sinfo)6279 void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
6280 {
6281 	unsigned long nr_slabs = 0;
6282 	unsigned long nr_objs = 0;
6283 	unsigned long nr_free = 0;
6284 	int node;
6285 	struct kmem_cache_node *n;
6286 
6287 	for_each_kmem_cache_node(s, node, n) {
6288 		nr_slabs += node_nr_slabs(n);
6289 		nr_objs += node_nr_objs(n);
6290 		nr_free += count_partial(n, count_free);
6291 	}
6292 
6293 	sinfo->active_objs = nr_objs - nr_free;
6294 	sinfo->num_objs = nr_objs;
6295 	sinfo->active_slabs = nr_slabs;
6296 	sinfo->num_slabs = nr_slabs;
6297 	sinfo->objects_per_slab = oo_objects(s->oo);
6298 	sinfo->cache_order = oo_order(s->oo);
6299 }
6300 
slabinfo_show_stats(struct seq_file * m,struct kmem_cache * s)6301 void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
6302 {
6303 }
6304 
slabinfo_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos)6305 ssize_t slabinfo_write(struct file *file, const char __user *buffer,
6306 		       size_t count, loff_t *ppos)
6307 {
6308 	return -EIO;
6309 }
6310 #endif /* CONFIG_SLUB_DEBUG */
6311