slab.c 112 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
/*
 * linux/mm/slab.c
 * Written by Mark Hemment, 1996/97.
 * (markhe@nextd.demon.co.uk)
 *
 * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
 *
 * Major cleanup, different bufctl logic, per-cpu arrays
 *	(c) 2000 Manfred Spraul
 *
 * Cleanup, make the head arrays unconditional, preparation for NUMA
 * 	(c) 2002 Manfred Spraul
 *
 * An implementation of the Slab Allocator as described in outline in;
 *	UNIX Internals: The New Frontiers by Uresh Vahalia
 *	Pub: Prentice Hall	ISBN 0-13-101908-2
 * or with a little more detail in;
 *	The Slab Allocator: An Object-Caching Kernel Memory Allocator
 *	Jeff Bonwick (Sun Microsystems).
 *	Presented at: USENIX Summer 1994 Technical Conference
 *
 * The memory is organized in caches, one cache for each object type.
 * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
 * Each cache consists out of many slabs (they are small (usually one
 * page long) and always contiguous), and each slab contains multiple
 * initialized objects.
 *
 * This means, that your constructor is used only for newly allocated
Simon Arlott's avatar
Simon Arlott committed
29
 * slabs and you must pass objects with the same initializations to
Linus Torvalds's avatar
Linus Torvalds committed
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
 * kmem_cache_free.
 *
 * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
 * normal). If you need a special memory type, then must create a new
 * cache for that memory type.
 *
 * In order to reduce fragmentation, the slabs are sorted in 3 groups:
 *   full slabs with 0 free objects
 *   partial slabs
 *   empty slabs with no allocated objects
 *
 * If partial slabs exist, then new allocations come from these slabs,
 * otherwise from empty slabs or new slabs are allocated.
 *
 * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
 * during kmem_cache_destroy(). The caller must prevent concurrent allocs.
 *
 * Each cache has a short per-cpu head array, most allocs
 * and frees go into that array, and if that array overflows, then 1/2
 * of the entries in the array are given back into the global cache.
 * The head array is strictly LIFO and should improve the cache hit rates.
 * On SMP, it additionally reduces the spinlock operations.
 *
Andrew Morton's avatar
Andrew Morton committed
53
 * The c_cpuarray may not be read with enabled local interrupts -
Linus Torvalds's avatar
Linus Torvalds committed
54
55
56
57
 * it's changed with a smp_call_function().
 *
 * SMP synchronization:
 *  constructors and destructors are called without any locking.
58
 *  Several members in struct kmem_cache and struct slab never change, they
Linus Torvalds's avatar
Linus Torvalds committed
59
60
61
62
63
64
65
66
67
68
69
70
 *	are accessed without any locking.
 *  The per-cpu arrays are never accessed from the wrong cpu, no locking,
 *  	and local interrupts are disabled so slab code is preempt-safe.
 *  The non-constant members are protected with a per-cache irq spinlock.
 *
 * Many thanks to Mark Hemment, who wrote another per-cpu slab patch
 * in 2000 - many ideas in the current implementation are derived from
 * his patch.
 *
 * Further notes from the original documentation:
 *
 * 11 April '97.  Started multi-threading - markhe
71
 *	The global cache-chain is protected by the mutex 'slab_mutex'.
Linus Torvalds's avatar
Linus Torvalds committed
72
73
74
75
76
77
 *	The sem is only needed when accessing/extending the cache-chain, which
 *	can never happen inside an interrupt (kmem_cache_create(),
 *	kmem_cache_shrink() and kmem_cache_reap()).
 *
 *	At present, each engine can be growing a cache.  This should be blocked.
 *
78
79
80
81
82
83
84
85
86
 * 15 March 2005. NUMA slab allocator.
 *	Shai Fultheim <shai@scalex86.org>.
 *	Shobhit Dayal <shobhit@calsoftinc.com>
 *	Alok N Kataria <alokk@calsoftinc.com>
 *	Christoph Lameter <christoph@lameter.com>
 *
 *	Modified the slab allocator to be node aware on NUMA systems.
 *	Each node has its own list of partial, free and full slabs.
 *	All object allocations for a node occur from node specific slab lists.
Linus Torvalds's avatar
Linus Torvalds committed
87
88
89
90
 */

#include	<linux/slab.h>
#include	<linux/mm.h>
91
#include	<linux/poison.h>
Linus Torvalds's avatar
Linus Torvalds committed
92
93
94
95
96
#include	<linux/swap.h>
#include	<linux/cache.h>
#include	<linux/interrupt.h>
#include	<linux/init.h>
#include	<linux/compiler.h>
97
#include	<linux/cpuset.h>
98
#include	<linux/proc_fs.h>
Linus Torvalds's avatar
Linus Torvalds committed
99
100
101
102
103
104
105
#include	<linux/seq_file.h>
#include	<linux/notifier.h>
#include	<linux/kallsyms.h>
#include	<linux/cpu.h>
#include	<linux/sysctl.h>
#include	<linux/module.h>
#include	<linux/rcupdate.h>
106
#include	<linux/string.h>
107
#include	<linux/uaccess.h>
108
#include	<linux/nodemask.h>
109
#include	<linux/kmemleak.h>
110
#include	<linux/mempolicy.h>
Ingo Molnar's avatar
Ingo Molnar committed
111
#include	<linux/mutex.h>
112
#include	<linux/fault-inject.h>
Ingo Molnar's avatar
Ingo Molnar committed
113
#include	<linux/rtmutex.h>
114
#include	<linux/reciprocal_div.h>
115
#include	<linux/debugobjects.h>
Pekka Enberg's avatar
Pekka Enberg committed
116
#include	<linux/kmemcheck.h>
117
#include	<linux/memory.h>
118
#include	<linux/prefetch.h>
Linus Torvalds's avatar
Linus Torvalds committed
119

120
121
#include	<net/sock.h>

Linus Torvalds's avatar
Linus Torvalds committed
122
123
124
125
#include	<asm/cacheflush.h>
#include	<asm/tlbflush.h>
#include	<asm/page.h>

126
127
#include <trace/events/kmem.h>

128
129
#include	"internal.h"

130
131
#include	"slab.h"

Linus Torvalds's avatar
Linus Torvalds committed
132
/*
133
 * DEBUG	- 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
Linus Torvalds's avatar
Linus Torvalds committed
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
 *		  0 for faster, smaller code (especially in the critical paths).
 *
 * STATS	- 1 to collect stats for /proc/slabinfo.
 *		  0 for faster, smaller code (especially in the critical paths).
 *
 * FORCED_DEBUG	- 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
 */

#ifdef CONFIG_DEBUG_SLAB
#define	DEBUG		1
#define	STATS		1
#define	FORCED_DEBUG	1
#else
#define	DEBUG		0
#define	STATS		0
#define	FORCED_DEBUG	0
#endif

/* Shouldn't this be in a header file somewhere? */
#define	BYTES_PER_WORD		sizeof(void *)
David Woodhouse's avatar
David Woodhouse committed
154
#define	REDZONE_ALIGN		max(BYTES_PER_WORD, __alignof__(unsigned long long))
Linus Torvalds's avatar
Linus Torvalds committed
155
156
157
158
159

#ifndef ARCH_KMALLOC_FLAGS
#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
#endif

160
161
162
163
164
165
166
167
168
#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
				<= SLAB_OBJ_MIN_SIZE) ? 1 : 0)

#if FREELIST_BYTE_INDEX
typedef unsigned char freelist_idx_t;
#else
typedef unsigned short freelist_idx_t;
#endif

169
#define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
170

171
172
173
174
175
176
/*
 * true if a page was allocated from pfmemalloc reserves for network-based
 * swap
 */
static bool pfmemalloc_active __read_mostly;

Linus Torvalds's avatar
Linus Torvalds committed
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
/*
 * struct array_cache
 *
 * Purpose:
 * - LIFO ordering, to hand out cache-warm objects from _alloc
 * - reduce the number of linked list operations
 * - reduce spinlock operations
 *
 * The limit is stored in the per-cpu structure to reduce the data cache
 * footprint.
 *
 */
struct array_cache {
	unsigned int avail;
	unsigned int limit;
	unsigned int batchcount;
	unsigned int touched;
194
	spinlock_t lock;
195
	void *entry[];	/*
Andrew Morton's avatar
Andrew Morton committed
196
197
198
			 * Must have this definition in here for the proper
			 * alignment of array_cache. Also simplifies accessing
			 * the entries.
199
200
201
202
			 *
			 * Entries should not be directly dereferenced as
			 * entries belonging to slabs marked pfmemalloc will
			 * have the lower bits set SLAB_OBJ_PFMEMALLOC
Andrew Morton's avatar
Andrew Morton committed
203
			 */
Linus Torvalds's avatar
Linus Torvalds committed
204
205
};

206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
#define SLAB_OBJ_PFMEMALLOC	1
static inline bool is_obj_pfmemalloc(void *objp)
{
	return (unsigned long)objp & SLAB_OBJ_PFMEMALLOC;
}

static inline void set_obj_pfmemalloc(void **objp)
{
	*objp = (void *)((unsigned long)*objp | SLAB_OBJ_PFMEMALLOC);
	return;
}

static inline void clear_obj_pfmemalloc(void **objp)
{
	*objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
}

Andrew Morton's avatar
Andrew Morton committed
223
224
225
/*
 * bootstrap: The caches do not work without cpuarrays anymore, but the
 * cpuarrays are allocated from the generic caches...
Linus Torvalds's avatar
Linus Torvalds committed
226
227
228
229
 */
#define BOOT_CPUCACHE_ENTRIES	1
struct arraycache_init {
	struct array_cache cache;
230
	void *entries[BOOT_CPUCACHE_ENTRIES];
Linus Torvalds's avatar
Linus Torvalds committed
231
232
};

233
234
235
/*
 * Need this for bootstrapping a per node allocator.
 */
236
#define NUM_INIT_LISTS (3 * MAX_NUMNODES)
237
static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
238
#define	CACHE_CACHE 0
239
#define	SIZE_AC MAX_NUMNODES
240
#define	SIZE_NODE (2 * MAX_NUMNODES)
241

242
static int drain_freelist(struct kmem_cache *cache,
243
			struct kmem_cache_node *n, int tofree);
244
static void free_block(struct kmem_cache *cachep, void **objpp, int len,
245
246
			int node, struct list_head *list);
static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
247
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
248
static void cache_reap(struct work_struct *unused);
249

250
251
static int slab_early_init = 1;

252
#define INDEX_AC kmalloc_index(sizeof(struct arraycache_init))
253
#define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
Linus Torvalds's avatar
Linus Torvalds committed
254

255
static void kmem_cache_node_init(struct kmem_cache_node *parent)
256
257
258
259
260
261
{
	INIT_LIST_HEAD(&parent->slabs_full);
	INIT_LIST_HEAD(&parent->slabs_partial);
	INIT_LIST_HEAD(&parent->slabs_free);
	parent->shared = NULL;
	parent->alien = NULL;
262
	parent->colour_next = 0;
263
264
265
266
267
	spin_lock_init(&parent->list_lock);
	parent->free_objects = 0;
	parent->free_touched = 0;
}

Andrew Morton's avatar
Andrew Morton committed
268
269
270
#define MAKE_LIST(cachep, listp, slab, nodeid)				\
	do {								\
		INIT_LIST_HEAD(listp);					\
271
		list_splice(&get_node(cachep, nodeid)->slab, listp);	\
272
273
	} while (0)

Andrew Morton's avatar
Andrew Morton committed
274
275
#define	MAKE_ALL_LISTS(cachep, ptr, nodeid)				\
	do {								\
276
277
278
279
	MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid);	\
	MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
	MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid);	\
	} while (0)
Linus Torvalds's avatar
Linus Torvalds committed
280
281
282
283
284

#define CFLGS_OFF_SLAB		(0x80000000UL)
#define	OFF_SLAB(x)	((x)->flags & CFLGS_OFF_SLAB)

#define BATCHREFILL_LIMIT	16
Andrew Morton's avatar
Andrew Morton committed
285
286
287
/*
 * Optimization question: fewer reaps means less probability for unnessary
 * cpucache drain/refill cycles.
Linus Torvalds's avatar
Linus Torvalds committed
288
 *
Adrian Bunk's avatar
Adrian Bunk committed
289
 * OTOH the cpuarrays can contain lots of objects,
Linus Torvalds's avatar
Linus Torvalds committed
290
291
 * which could lock up otherwise freeable slabs.
 */
292
293
#define REAPTIMEOUT_AC		(2*HZ)
#define REAPTIMEOUT_NODE	(4*HZ)
Linus Torvalds's avatar
Linus Torvalds committed
294
295
296
297
298
299

#if STATS
#define	STATS_INC_ACTIVE(x)	((x)->num_active++)
#define	STATS_DEC_ACTIVE(x)	((x)->num_active--)
#define	STATS_INC_ALLOCED(x)	((x)->num_allocations++)
#define	STATS_INC_GROWN(x)	((x)->grown++)
300
#define	STATS_ADD_REAPED(x,y)	((x)->reaped += (y))
Andrew Morton's avatar
Andrew Morton committed
301
302
303
304
305
#define	STATS_SET_HIGH(x)						\
	do {								\
		if ((x)->num_active > (x)->high_mark)			\
			(x)->high_mark = (x)->num_active;		\
	} while (0)
Linus Torvalds's avatar
Linus Torvalds committed
306
307
#define	STATS_INC_ERR(x)	((x)->errors++)
#define	STATS_INC_NODEALLOCS(x)	((x)->node_allocs++)
308
#define	STATS_INC_NODEFREES(x)	((x)->node_frees++)
309
#define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
Andrew Morton's avatar
Andrew Morton committed
310
311
312
313
314
#define	STATS_SET_FREEABLE(x, i)					\
	do {								\
		if ((x)->max_freeable < i)				\
			(x)->max_freeable = i;				\
	} while (0)
Linus Torvalds's avatar
Linus Torvalds committed
315
316
317
318
319
320
321
322
323
#define STATS_INC_ALLOCHIT(x)	atomic_inc(&(x)->allochit)
#define STATS_INC_ALLOCMISS(x)	atomic_inc(&(x)->allocmiss)
#define STATS_INC_FREEHIT(x)	atomic_inc(&(x)->freehit)
#define STATS_INC_FREEMISS(x)	atomic_inc(&(x)->freemiss)
#else
#define	STATS_INC_ACTIVE(x)	do { } while (0)
#define	STATS_DEC_ACTIVE(x)	do { } while (0)
#define	STATS_INC_ALLOCED(x)	do { } while (0)
#define	STATS_INC_GROWN(x)	do { } while (0)
324
#define	STATS_ADD_REAPED(x,y)	do { (void)(y); } while (0)
Linus Torvalds's avatar
Linus Torvalds committed
325
326
327
#define	STATS_SET_HIGH(x)	do { } while (0)
#define	STATS_INC_ERR(x)	do { } while (0)
#define	STATS_INC_NODEALLOCS(x)	do { } while (0)
328
#define	STATS_INC_NODEFREES(x)	do { } while (0)
329
#define STATS_INC_ACOVERFLOW(x)   do { } while (0)
Andrew Morton's avatar
Andrew Morton committed
330
#define	STATS_SET_FREEABLE(x, i) do { } while (0)
Linus Torvalds's avatar
Linus Torvalds committed
331
332
333
334
335
336
337
338
#define STATS_INC_ALLOCHIT(x)	do { } while (0)
#define STATS_INC_ALLOCMISS(x)	do { } while (0)
#define STATS_INC_FREEHIT(x)	do { } while (0)
#define STATS_INC_FREEMISS(x)	do { } while (0)
#endif

#if DEBUG

Andrew Morton's avatar
Andrew Morton committed
339
340
/*
 * memory layout of objects:
Linus Torvalds's avatar
Linus Torvalds committed
341
 * 0		: objp
342
 * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
Linus Torvalds's avatar
Linus Torvalds committed
343
344
 * 		the end of an object is aligned with the end of the real
 * 		allocation. Catches writes behind the end of the allocation.
345
 * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
Linus Torvalds's avatar
Linus Torvalds committed
346
 * 		redzone word.
347
 * cachep->obj_offset: The real object.
348
349
 * cachep->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
 * cachep->size - 1* BYTES_PER_WORD: last caller address
Andrew Morton's avatar
Andrew Morton committed
350
 *					[BYTES_PER_WORD long]
Linus Torvalds's avatar
Linus Torvalds committed
351
 */
352
static int obj_offset(struct kmem_cache *cachep)
Linus Torvalds's avatar
Linus Torvalds committed
353
{
354
	return cachep->obj_offset;
Linus Torvalds's avatar
Linus Torvalds committed
355
356
}

357
static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
Linus Torvalds's avatar
Linus Torvalds committed
358
359
{
	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
360
361
	return (unsigned long long*) (objp + obj_offset(cachep) -
				      sizeof(unsigned long long));
Linus Torvalds's avatar
Linus Torvalds committed
362
363
}

364
static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
Linus Torvalds's avatar
Linus Torvalds committed
365
366
367
{
	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
	if (cachep->flags & SLAB_STORE_USER)
368
		return (unsigned long long *)(objp + cachep->size -
369
					      sizeof(unsigned long long) -
David Woodhouse's avatar
David Woodhouse committed
370
					      REDZONE_ALIGN);
371
	return (unsigned long long *) (objp + cachep->size -
372
				       sizeof(unsigned long long));
Linus Torvalds's avatar
Linus Torvalds committed
373
374
}

375
static void **dbg_userword(struct kmem_cache *cachep, void *objp)
Linus Torvalds's avatar
Linus Torvalds committed
376
377
{
	BUG_ON(!(cachep->flags & SLAB_STORE_USER));
378
	return (void **)(objp + cachep->size - BYTES_PER_WORD);
Linus Torvalds's avatar
Linus Torvalds committed
379
380
381
382
}

#else

383
#define obj_offset(x)			0
384
385
#define dbg_redzone1(cachep, objp)	({BUG(); (unsigned long long *)NULL;})
#define dbg_redzone2(cachep, objp)	({BUG(); (unsigned long long *)NULL;})
Linus Torvalds's avatar
Linus Torvalds committed
386
387
388
389
#define dbg_userword(cachep, objp)	({BUG(); (void **)NULL;})

#endif

390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
#define OBJECT_FREE (0)
#define OBJECT_ACTIVE (1)

#ifdef CONFIG_DEBUG_SLAB_LEAK

static void set_obj_status(struct page *page, int idx, int val)
{
	int freelist_size;
	char *status;
	struct kmem_cache *cachep = page->slab_cache;

	freelist_size = cachep->num * sizeof(freelist_idx_t);
	status = (char *)page->freelist + freelist_size;
	status[idx] = val;
}

static inline unsigned int get_obj_status(struct page *page, int idx)
{
	int freelist_size;
	char *status;
	struct kmem_cache *cachep = page->slab_cache;

	freelist_size = cachep->num * sizeof(freelist_idx_t);
	status = (char *)page->freelist + freelist_size;

	return status[idx];
}

#else
static inline void set_obj_status(struct page *page, int idx, int val) {}

#endif

Linus Torvalds's avatar
Linus Torvalds committed
423
/*
424
425
 * Do not go above this order unless 0 objects fit into the slab or
 * overridden on the command line.
Linus Torvalds's avatar
Linus Torvalds committed
426
 */
427
428
429
#define	SLAB_MAX_ORDER_HI	1
#define	SLAB_MAX_ORDER_LO	0
static int slab_max_order = SLAB_MAX_ORDER_LO;
430
static bool slab_max_order_set __initdata;
Linus Torvalds's avatar
Linus Torvalds committed
431

432
433
static inline struct kmem_cache *virt_to_cache(const void *obj)
{
434
	struct page *page = virt_to_head_page(obj);
435
	return page->slab_cache;
436
437
}

438
static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
439
440
				 unsigned int idx)
{
441
	return page->s_mem + cache->size * idx;
442
443
}

444
/*
445
446
447
 * We want to avoid an expensive divide : (offset / cache->size)
 *   Using the fact that size is a constant for a particular cache,
 *   we can replace (offset / cache->size) by
448
449
450
 *   reciprocal_divide(offset, cache->reciprocal_buffer_size)
 */
static inline unsigned int obj_to_index(const struct kmem_cache *cache,
451
					const struct page *page, void *obj)
452
{
453
	u32 offset = (obj - page->s_mem);
454
	return reciprocal_divide(offset, cache->reciprocal_buffer_size);
455
456
}

Linus Torvalds's avatar
Linus Torvalds committed
457
static struct arraycache_init initarray_generic =
458
    { {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
Linus Torvalds's avatar
Linus Torvalds committed
459
460

/* internal cache of cache description objs */
461
static struct kmem_cache kmem_cache_boot = {
462
463
464
	.batchcount = 1,
	.limit = BOOT_CPUCACHE_ENTRIES,
	.shared = 1,
465
	.size = sizeof(struct kmem_cache),
466
	.name = "kmem_cache",
Linus Torvalds's avatar
Linus Torvalds committed
467
468
};

469
470
#define BAD_ALIEN_MAGIC 0x01020304ul

471
472
473
474
475
476
477
478
#ifdef CONFIG_LOCKDEP

/*
 * Slab sometimes uses the kmalloc slabs to store the slab headers
 * for other slabs "off slab".
 * The locking for this is tricky in that it nests within the locks
 * of all other slabs in a few places; to deal with this special
 * locking we put on-slab caches into a separate lock-class.
479
480
481
482
 *
 * We set lock class for alien array caches which are up during init.
 * The lock annotation will be lost if all cpus of a node goes down and
 * then comes back up during hotplug
483
 */
484
485
486
static struct lock_class_key on_slab_l3_key;
static struct lock_class_key on_slab_alc_key;

487
488
489
490
491
static struct lock_class_key debugobj_l3_key;
static struct lock_class_key debugobj_alc_key;

static void slab_set_lock_classes(struct kmem_cache *cachep,
		struct lock_class_key *l3_key, struct lock_class_key *alc_key,
492
		struct kmem_cache_node *n)
493
494
495
496
{
	struct array_cache **alc;
	int r;

497
498
	lockdep_set_class(&n->list_lock, l3_key);
	alc = n->alien;
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
	/*
	 * FIXME: This check for BAD_ALIEN_MAGIC
	 * should go away when common slab code is taught to
	 * work even without alien caches.
	 * Currently, non NUMA code returns BAD_ALIEN_MAGIC
	 * for alloc_alien_cache,
	 */
	if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
		return;
	for_each_node(r) {
		if (alc[r])
			lockdep_set_class(&alc[r]->lock, alc_key);
	}
}

514
515
static void slab_set_debugobj_lock_classes_node(struct kmem_cache *cachep,
	struct kmem_cache_node *n)
516
{
517
	slab_set_lock_classes(cachep, &debugobj_l3_key, &debugobj_alc_key, n);
518
519
520
521
522
}

static void slab_set_debugobj_lock_classes(struct kmem_cache *cachep)
{
	int node;
523
	struct kmem_cache_node *n;
524

525
526
	for_each_kmem_cache_node(cachep, node, n)
		slab_set_debugobj_lock_classes_node(cachep, n);
527
528
}

529
static void init_node_lock_keys(int q)
530
{
531
	int i;
532

533
	if (slab_state < UP)
534
535
		return;

Christoph Lameter's avatar
Christoph Lameter committed
536
	for (i = 1; i <= KMALLOC_SHIFT_HIGH; i++) {
537
		struct kmem_cache_node *n;
538
539
540
541
		struct kmem_cache *cache = kmalloc_caches[i];

		if (!cache)
			continue;
542

543
		n = get_node(cache, q);
544
		if (!n || OFF_SLAB(cache))
545
			continue;
546

547
		slab_set_lock_classes(cache, &on_slab_l3_key,
548
				&on_slab_alc_key, n);
549
550
	}
}
551

552
553
static void on_slab_lock_classes_node(struct kmem_cache *cachep,
	struct kmem_cache_node *n)
554
555
{
	slab_set_lock_classes(cachep, &on_slab_l3_key,
556
			&on_slab_alc_key, n);
557
558
559
560
561
}

static inline void on_slab_lock_classes(struct kmem_cache *cachep)
{
	int node;
562
	struct kmem_cache_node *n;
563
564

	VM_BUG_ON(OFF_SLAB(cachep));
565
566
	for_each_kmem_cache_node(cachep, node, n)
		on_slab_lock_classes_node(cachep, n);
567
568
}

569
static inline void __init init_lock_keys(void)
570
571
572
573
574
575
{
	int node;

	for_each_node(node)
		init_node_lock_keys(node);
}
576
#else
577
static void __init init_node_lock_keys(int q)
578
579
580
{
}

581
static inline void init_lock_keys(void)
582
583
{
}
584

585
586
587
588
static inline void on_slab_lock_classes(struct kmem_cache *cachep)
{
}

589
590
static inline void on_slab_lock_classes_node(struct kmem_cache *cachep,
	struct kmem_cache_node *n)
591
592
593
{
}

594
595
static void slab_set_debugobj_lock_classes_node(struct kmem_cache *cachep,
	struct kmem_cache_node *n)
596
597
598
599
600
601
{
}

static void slab_set_debugobj_lock_classes(struct kmem_cache *cachep)
{
}
602
603
#endif

604
static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
Linus Torvalds's avatar
Linus Torvalds committed
605

606
static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
Linus Torvalds's avatar
Linus Torvalds committed
607
608
609
610
{
	return cachep->array[smp_processor_id()];
}

611
612
613
614
615
616
617
618
619
620
621
622
623
624
static size_t calculate_freelist_size(int nr_objs, size_t align)
{
	size_t freelist_size;

	freelist_size = nr_objs * sizeof(freelist_idx_t);
	if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK))
		freelist_size += nr_objs * sizeof(char);

	if (align)
		freelist_size = ALIGN(freelist_size, align);

	return freelist_size;
}

625
626
static int calculate_nr_objs(size_t slab_size, size_t buffer_size,
				size_t idx_size, size_t align)
Linus Torvalds's avatar
Linus Torvalds committed
627
{
628
	int nr_objs;
629
	size_t remained_size;
630
	size_t freelist_size;
631
	int extra_space = 0;
632

633
634
	if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK))
		extra_space = sizeof(char);
635
636
637
638
639
640
641
642
	/*
	 * Ignore padding for the initial guess. The padding
	 * is at most @align-1 bytes, and @buffer_size is at
	 * least @align. In the worst case, this result will
	 * be one greater than the number of objects that fit
	 * into the memory allocation when taking the padding
	 * into account.
	 */
643
	nr_objs = slab_size / (buffer_size + idx_size + extra_space);
644
645
646
647
648

	/*
	 * This calculated number will be either the right
	 * amount, or one greater than what we want.
	 */
649
650
651
	remained_size = slab_size - nr_objs * buffer_size;
	freelist_size = calculate_freelist_size(nr_objs, align);
	if (remained_size < freelist_size)
652
653
654
		nr_objs--;

	return nr_objs;
655
}
Linus Torvalds's avatar
Linus Torvalds committed
656

Andrew Morton's avatar
Andrew Morton committed
657
658
659
/*
 * Calculate the number of objects and left-over bytes for a given buffer size.
 */
660
661
662
663
664
665
666
static void cache_estimate(unsigned long gfporder, size_t buffer_size,
			   size_t align, int flags, size_t *left_over,
			   unsigned int *num)
{
	int nr_objs;
	size_t mgmt_size;
	size_t slab_size = PAGE_SIZE << gfporder;
Linus Torvalds's avatar
Linus Torvalds committed
667

668
669
670
671
672
	/*
	 * The slab management structure can be either off the slab or
	 * on it. For the latter case, the memory allocated for a
	 * slab is used for:
	 *
Joonsoo Kim's avatar
Joonsoo Kim committed
673
	 * - One unsigned int for each object
674
675
676
677
678
679
680
681
682
683
684
685
686
	 * - Padding to respect alignment of @align
	 * - @buffer_size bytes for each object
	 *
	 * If the slab management structure is off the slab, then the
	 * alignment will already be calculated into the size. Because
	 * the slabs are all pages aligned, the objects will be at the
	 * correct alignment when allocated.
	 */
	if (flags & CFLGS_OFF_SLAB) {
		mgmt_size = 0;
		nr_objs = slab_size / buffer_size;

	} else {
687
		nr_objs = calculate_nr_objs(slab_size, buffer_size,
688
					sizeof(freelist_idx_t), align);
689
		mgmt_size = calculate_freelist_size(nr_objs, align);
690
691
692
	}
	*num = nr_objs;
	*left_over = slab_size - nr_objs*buffer_size - mgmt_size;
Linus Torvalds's avatar
Linus Torvalds committed
693
694
}

695
#if DEBUG
696
#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
Linus Torvalds's avatar
Linus Torvalds committed
697

Andrew Morton's avatar
Andrew Morton committed
698
699
static void __slab_error(const char *function, struct kmem_cache *cachep,
			char *msg)
Linus Torvalds's avatar
Linus Torvalds committed
700
701
{
	printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
702
	       function, cachep->name, msg);
Linus Torvalds's avatar
Linus Torvalds committed
703
	dump_stack();
704
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
Linus Torvalds's avatar
Linus Torvalds committed
705
}
706
#endif
Linus Torvalds's avatar
Linus Torvalds committed
707

708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
/*
 * By default on NUMA we use alien caches to stage the freeing of
 * objects allocated from other nodes. This causes massive memory
 * inefficiencies when using fake NUMA setup to split memory into a
 * large number of small nodes, so it can be disabled on the command
 * line
  */

static int use_alien_caches __read_mostly = 1;
static int __init noaliencache_setup(char *s)
{
	use_alien_caches = 0;
	return 1;
}
__setup("noaliencache", noaliencache_setup);

724
725
726
727
728
729
730
731
732
733
734
static int __init slab_max_order_setup(char *str)
{
	get_option(&str, &slab_max_order);
	slab_max_order = slab_max_order < 0 ? 0 :
				min(slab_max_order, MAX_ORDER - 1);
	slab_max_order_set = true;

	return 1;
}
__setup("slab_max_order=", slab_max_order_setup);

735
736
737
738
739
740
741
#ifdef CONFIG_NUMA
/*
 * Special reaping functions for NUMA systems called from cache_reap().
 * These take care of doing round robin flushing of alien caches (containing
 * objects freed on different nodes from which they were allocated) and the
 * flushing of remote pcps by calling drain_node_pages.
 */
742
static DEFINE_PER_CPU(unsigned long, slab_reap_node);
743
744
745
746
747

static void init_reap_node(int cpu)
{
	int node;

748
	node = next_node(cpu_to_mem(cpu), node_online_map);
749
	if (node == MAX_NUMNODES)
750
		node = first_node(node_online_map);
751

752
	per_cpu(slab_reap_node, cpu) = node;
753
754
755
756
}

static void next_reap_node(void)
{
757
	int node = __this_cpu_read(slab_reap_node);
758
759
760
761

	node = next_node(node, node_online_map);
	if (unlikely(node >= MAX_NUMNODES))
		node = first_node(node_online_map);
762
	__this_cpu_write(slab_reap_node, node);
763
764
765
766
767
768
769
}

#else
#define init_reap_node(cpu) do { } while (0)
#define next_reap_node(void) do { } while (0)
#endif

Linus Torvalds's avatar
Linus Torvalds committed
770
771
772
773
774
775
776
/*
 * Initiate the reap timer running on the target CPU.  We run at around 1 to 2Hz
 * via the workqueue/eventd.
 * Add the CPU number into the expiration time to minimize the possibility of
 * the CPUs getting into lockstep and contending for the global cache chain
 * lock.
 */
777
static void start_cpu_timer(int cpu)
Linus Torvalds's avatar
Linus Torvalds committed
778
{
779
	struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
Linus Torvalds's avatar
Linus Torvalds committed
780
781
782
783
784
785

	/*
	 * When this gets called from do_initcalls via cpucache_init(),
	 * init_workqueues() has already run, so keventd will be setup
	 * at that time.
	 */
786
	if (keventd_up() && reap_work->work.func == NULL) {
787
		init_reap_node(cpu);
788
		INIT_DEFERRABLE_WORK(reap_work, cache_reap);
789
790
		schedule_delayed_work_on(cpu, reap_work,
					__round_jiffies_relative(HZ, cpu));
Linus Torvalds's avatar
Linus Torvalds committed
791
792
793
	}
}

794
static void init_arraycache(struct array_cache *ac, int limit, int batch)
Linus Torvalds's avatar
Linus Torvalds committed
795
{
796
797
	/*
	 * The array_cache structures contain pointers to free object.
Lucas De Marchi's avatar
Lucas De Marchi committed
798
	 * However, when such objects are allocated or transferred to another
799
800
801
802
	 * cache the pointers are not cleared and they could be counted as
	 * valid references during a kmemleak scan. Therefore, kmemleak must
	 * not scan such objects.
	 */
803
804
805
806
807
808
809
	kmemleak_no_scan(ac);
	if (ac) {
		ac->avail = 0;
		ac->limit = limit;
		ac->batchcount = batch;
		ac->touched = 0;
		spin_lock_init(&ac->lock);
Linus Torvalds's avatar
Linus Torvalds committed
810
	}
811
812
813
814
815
816
817
818
819
820
821
}

static struct array_cache *alloc_arraycache(int node, int entries,
					    int batchcount, gfp_t gfp)
{
	int memsize = sizeof(void *) * entries + sizeof(struct array_cache);
	struct array_cache *ac = NULL;

	ac = kmalloc_node(memsize, gfp, node);
	init_arraycache(ac, entries, batchcount);
	return ac;
Linus Torvalds's avatar
Linus Torvalds committed
822
823
}

824
static inline bool is_slab_pfmemalloc(struct page *page)
825
826
827
828
829
830
831
832
{
	return PageSlabPfmemalloc(page);
}

/* Clears pfmemalloc_active if no slabs have pfmalloc set */
static void recheck_pfmemalloc_active(struct kmem_cache *cachep,
						struct array_cache *ac)
{
833
	struct kmem_cache_node *n = get_node(cachep, numa_mem_id());
834
	struct page *page;
835
836
837
838
839
	unsigned long flags;

	if (!pfmemalloc_active)
		return;

840
	spin_lock_irqsave(&n->list_lock, flags);
841
842
	list_for_each_entry(page, &n->slabs_full, lru)
		if (is_slab_pfmemalloc(page))
843
844
			goto out;

845
846
	list_for_each_entry(page, &n->slabs_partial, lru)
		if (is_slab_pfmemalloc(page))
847
848
			goto out;

849
850
	list_for_each_entry(page, &n->slabs_free, lru)
		if (is_slab_pfmemalloc(page))
851
852
853
854
			goto out;

	pfmemalloc_active = false;
out:
855
	spin_unlock_irqrestore(&n->list_lock, flags);
856
857
}

858
static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
859
860
861
862
863
864
865
						gfp_t flags, bool force_refill)
{
	int i;
	void *objp = ac->entry[--ac->avail];

	/* Ensure the caller is allowed to use objects from PFMEMALLOC slab */
	if (unlikely(is_obj_pfmemalloc(objp))) {
866
		struct kmem_cache_node *n;
867
868
869
870
871
872
873

		if (gfp_pfmemalloc_allowed(flags)) {
			clear_obj_pfmemalloc(&objp);
			return objp;
		}

		/* The caller cannot use PFMEMALLOC objects, find another one */
874
		for (i = 0; i < ac->avail; i++) {
875
876
877
878
879
880
881
882
883
884
885
886
887
			/* If a !PFMEMALLOC object is found, swap them */
			if (!is_obj_pfmemalloc(ac->entry[i])) {
				objp = ac->entry[i];
				ac->entry[i] = ac->entry[ac->avail];
				ac->entry[ac->avail] = objp;
				return objp;
			}
		}

		/*
		 * If there are empty slabs on the slabs_free list and we are
		 * being forced to refill the cache, mark this one !pfmemalloc.
		 */
888
		n = get_node(cachep, numa_mem_id());
889
		if (!list_empty(&n->slabs_free) && force_refill) {
890
			struct page *page = virt_to_head_page(objp);
891
			ClearPageSlabPfmemalloc(page);
892
893
894
895
896
897
898
899
900
901
902
903
904
			clear_obj_pfmemalloc(&objp);
			recheck_pfmemalloc_active(cachep, ac);
			return objp;
		}

		/* No !PFMEMALLOC objects available */
		ac->avail++;
		objp = NULL;
	}

	return objp;
}

905
906
907
908
909
910
911
912
913
914
915
916
917
918
static inline void *ac_get_obj(struct kmem_cache *cachep,
			struct array_cache *ac, gfp_t flags, bool force_refill)
{
	void *objp;

	if (unlikely(sk_memalloc_socks()))
		objp = __ac_get_obj(cachep, ac, flags, force_refill);
	else
		objp = ac->entry[--ac->avail];

	return objp;
}

static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
919
920
921
922
								void *objp)
{
	if (unlikely(pfmemalloc_active)) {
		/* Some pfmemalloc slabs exist, check if this is one */
923
		struct page *page = virt_to_head_page(objp);
924
925
926
927
		if (PageSlabPfmemalloc(page))
			set_obj_pfmemalloc(&objp);
	}

928
929
930
931
932
933
934
935
936
	return objp;
}

static inline void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
								void *objp)
{
	if (unlikely(sk_memalloc_socks()))
		objp = __ac_put_obj(cachep, ac, objp);

937
938
939
	ac->entry[ac->avail++] = objp;
}

940
941
942
943
944
945
946
947
948
949
/*
 * Transfer objects in one arraycache to another.
 * Locking must be handled by the caller.
 *
 * Return the number of entries transferred.
 */
static int transfer_objects(struct array_cache *to,
		struct array_cache *from, unsigned int max)
{
	/* Figure out how many entries to transfer */
950
	int nr = min3(from->avail, max, to->limit - to->avail);
951
952
953
954
955
956
957
958
959
960
961
962

	if (!nr)
		return 0;

	memcpy(to->entry + to->avail, from->entry + from->avail -nr,
			sizeof(void *) *nr);

	from->avail -= nr;
	to->avail += nr;
	return nr;
}

963
964
965
#ifndef CONFIG_NUMA

#define drain_alien_cache(cachep, alien) do { } while (0)
966
#define reap_alien(cachep, n) do { } while (0)
967

968
static inline struct array_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
{
	return (struct array_cache **)BAD_ALIEN_MAGIC;
}

static inline void free_alien_cache(struct array_cache **ac_ptr)
{
}

static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
	return 0;
}

static inline void *alternate_node_alloc(struct kmem_cache *cachep,
		gfp_t flags)
{
	return NULL;
}

988
static inline void *____cache_alloc_node(struct kmem_cache *cachep,
989
990
991
992
993
994
995
		 gfp_t flags, int nodeid)
{
	return NULL;
}

#else	/* CONFIG_NUMA */

996
static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
997
static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
998

999
static struct array_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
1000
1001
{
	struct array_cache **ac_ptr;
1002
	int memsize = sizeof(void *) * nr_node_ids;
1003
1004
1005
1006
	int i;

	if (limit > 1)
		limit = 12;
1007
	ac_ptr = kzalloc_node(memsize, gfp, node);
1008
1009
	if (ac_ptr) {
		for_each_node(i) {
1010
			if (i == node || !node_online(i))
1011
				continue;
1012
			ac_ptr[i] = alloc_arraycache(node, limit, 0xbaadf00d, gfp);
1013
			if (!ac_ptr[i]) {
1014
				for (i--; i >= 0; i--)
1015
1016
1017
1018
1019
1020
1021
1022
1023
					kfree(ac_ptr[i]);
				kfree(ac_ptr);
				return NULL;
			}
		}
	}
	return ac_ptr;
}

Pekka Enberg's avatar
Pekka Enberg committed
1024
static void free_alien_cache(struct array_cache **ac_ptr)
1025
1026
1027
1028
1029
1030
{
	int i;

	if (!ac_ptr)
		return;
	for_each_node(i)
1031
	    kfree(ac_ptr[i]);
1032
1033
1034
	kfree(ac_ptr);
}

1035
static void __drain_alien_cache(struct kmem_cache *cachep,
Pekka Enberg's avatar
Pekka Enberg committed
1036
				struct array_cache *ac, int node)
1037
{
1038
	struct kmem_cache_node *n = get_node(cachep, node);
1039
	LIST_HEAD(list);
1040
1041

	if (ac->avail) {
1042
		spin_lock(&n->list_lock);
1043
1044
1045
1046
1047
		/*
		 * Stuff objects into the remote nodes shared array first.
		 * That way we could avoid the overhead of putting the objects
		 * into the free lists and getting them back later.
		 */
1048
1049
		if (n->shared)
			transfer_objects(n->shared, ac, ac->limit);
1050

1051
		free_block(cachep, ac->entry, ac->avail, node, &list);
1052
		ac->avail = 0;
1053
		spin_unlock(&n->list_lock);
1054
		slabs_destroy(cachep, &list);
1055
1056
1057
	}
}

1058
1059
1060
/*
 * Called from cache_reap() to regularly drain alien caches round robin.
 */
1061
static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
1062
{
1063
	int node = __this_cpu_read(slab_reap_node);
1064

1065
1066
	if (n->alien) {
		struct array_cache *ac = n->alien[node];
1067
1068

		if (ac && ac->avail && spin_trylock_irq(&ac->lock)) {
1069
1070
1071
1072
1073
1074
			__drain_alien_cache(cachep, ac, node);
			spin_unlock_irq(&ac->lock);
		}
	}
}

Andrew Morton's avatar
Andrew Morton committed
1075
1076
static void drain_alien_cache(struct kmem_cache *cachep,
				struct array_cache **alien)
1077
{
1078
	int i = 0;
1079
1080
1081
1082
	struct array_cache *ac;
	unsigned long flags;

	for_each_online_node(i) {
1083
		ac = alien[i];
1084
1085
1086
1087
1088
1089
1090
		if (ac) {
			spin_lock_irqsave(&ac->lock, flags);
			__drain_alien_cache(cachep, ac, i);
			spin_unlock_irqrestore(&ac->lock, flags);
		}
	}
}
1091

1092
static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
1093
{
1094
	int nodeid = page_to_nid(virt_to_page(objp));
1095
	struct kmem_cache_node *n;
1096
	struct array_cache *alien = NULL;
1097
	int node;
1098
	LIST_HEAD(list);
1099

1100
	node = numa_mem_id();
1101
1102
1103
1104
1105

	/*
	 * Make sure we are not freeing a object from another node to the array
	 * cache on this cpu.
	 */
1106
	if (likely(nodeid == node))
1107
1108
		return 0;

1109
	n = get_node(cachep, node);
1110
	STATS_INC_NODEFREES(cachep);
1111
1112
	if (n->alien && n->alien[nodeid]) {
		alien = n->alien[nodeid];
1113
		spin_lock(&alien->lock);
1114
1115
1116
1117
		if (unlikely(alien->avail == alien->limit)) {
			STATS_INC_ACOVERFLOW(cachep);
			__drain_alien_cache(cachep, alien, nodeid);
		}
1118
		ac_put_obj(cachep, alien, objp);
1119
1120
		spin_unlock(&alien->lock);
	} else {
1121
1122
		n = get_node(cachep, nodeid);
		spin_lock(&n->list_lock);
1123
		free_block(cachep, &objp, 1, nodeid, &list);
1124
		spin_unlock(&n->list_lock);
1125
		slabs_destroy(cachep, &list);
1126
1127
1128
	}
	return 1;
}
1129
1130
#endif

1131
/*
1132
 * Allocates and initializes node for a node on each slab cache, used for
1133
 * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
1134
 * will be allocated off-node since memory is not yet online for the new node.
1135
 * When hotplugging memory or a cpu, existing node are not replaced if
1136
1137
 * already in use.
 *
1138
 * Must hold slab_mutex.
1139
 */
1140
static int init_cache_node_node(int node)
1141
1142
{
	struct kmem_cache *cachep;
1143
	struct kmem_cache_node *n;
1144
	const int memsize = sizeof(struct kmem_cache_node);
1145

1146
	list_for_each_entry(cachep, &slab_caches, list) {
1147
		/*