slab.c 109 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
	void *entry[];	/*
Andrew Morton's avatar
Andrew Morton committed
195
196
197
			 * Must have this definition in here for the proper
			 * alignment of array_cache. Also simplifies accessing
			 * the entries.
198
199
200
201
			 *
			 * 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
202
			 */
Linus Torvalds's avatar
Linus Torvalds committed
203
204
};

Joonsoo Kim's avatar
Joonsoo Kim committed
205
206
207
208
209
struct alien_cache {
	spinlock_t lock;
	struct array_cache ac;
};

210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
#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);
}

227
228
229
/*
 * Need this for bootstrapping a per node allocator.
 */
230
#define NUM_INIT_LISTS (2 * MAX_NUMNODES)
231
static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
232
#define	CACHE_CACHE 0
233
#define	SIZE_NODE (MAX_NUMNODES)
234

235
static int drain_freelist(struct kmem_cache *cache,
236
			struct kmem_cache_node *n, int tofree);
237
static void free_block(struct kmem_cache *cachep, void **objpp, int len,
238
239
			int node, struct list_head *list);
static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
240
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
241
static void cache_reap(struct work_struct *unused);
242

243
244
static int slab_early_init = 1;

245
#define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
Linus Torvalds's avatar
Linus Torvalds committed
246

247
static void kmem_cache_node_init(struct kmem_cache_node *parent)
248
249
250
251
252
253
{
	INIT_LIST_HEAD(&parent->slabs_full);
	INIT_LIST_HEAD(&parent->slabs_partial);
	INIT_LIST_HEAD(&parent->slabs_free);
	parent->shared = NULL;
	parent->alien = NULL;
254
	parent->colour_next = 0;
255
256
257
258
259
	spin_lock_init(&parent->list_lock);
	parent->free_objects = 0;
	parent->free_touched = 0;
}

Andrew Morton's avatar
Andrew Morton committed
260
261
262
#define MAKE_LIST(cachep, listp, slab, nodeid)				\
	do {								\
		INIT_LIST_HEAD(listp);					\
263
		list_splice(&get_node(cachep, nodeid)->slab, listp);	\
264
265
	} while (0)

Andrew Morton's avatar
Andrew Morton committed
266
267
#define	MAKE_ALL_LISTS(cachep, ptr, nodeid)				\
	do {								\
268
269
270
271
	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
272

273
#define CFLGS_OBJFREELIST_SLAB	(0x40000000UL)
Linus Torvalds's avatar
Linus Torvalds committed
274
#define CFLGS_OFF_SLAB		(0x80000000UL)
275
#define	OBJFREELIST_SLAB(x)	((x)->flags & CFLGS_OBJFREELIST_SLAB)
Linus Torvalds's avatar
Linus Torvalds committed
276
277
278
#define	OFF_SLAB(x)	((x)->flags & CFLGS_OFF_SLAB)

#define BATCHREFILL_LIMIT	16
Andrew Morton's avatar
Andrew Morton committed
279
280
281
/*
 * Optimization question: fewer reaps means less probability for unnessary
 * cpucache drain/refill cycles.
Linus Torvalds's avatar
Linus Torvalds committed
282
 *
Adrian Bunk's avatar
Adrian Bunk committed
283
 * OTOH the cpuarrays can contain lots of objects,
Linus Torvalds's avatar
Linus Torvalds committed
284
285
 * which could lock up otherwise freeable slabs.
 */
286
287
#define REAPTIMEOUT_AC		(2*HZ)
#define REAPTIMEOUT_NODE	(4*HZ)
Linus Torvalds's avatar
Linus Torvalds committed
288
289
290
291
292
293

#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++)
294
#define	STATS_ADD_REAPED(x,y)	((x)->reaped += (y))
Andrew Morton's avatar
Andrew Morton committed
295
296
297
298
299
#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
300
301
#define	STATS_INC_ERR(x)	((x)->errors++)
#define	STATS_INC_NODEALLOCS(x)	((x)->node_allocs++)
302
#define	STATS_INC_NODEFREES(x)	((x)->node_frees++)
303
#define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
Andrew Morton's avatar
Andrew Morton committed
304
305
306
307
308
#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
309
310
311
312
313
314
315
316
317
#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)
318
#define	STATS_ADD_REAPED(x,y)	do { (void)(y); } while (0)
Linus Torvalds's avatar
Linus Torvalds committed
319
320
321
#define	STATS_SET_HIGH(x)	do { } while (0)
#define	STATS_INC_ERR(x)	do { } while (0)
#define	STATS_INC_NODEALLOCS(x)	do { } while (0)
322
#define	STATS_INC_NODEFREES(x)	do { } while (0)
323
#define STATS_INC_ACOVERFLOW(x)   do { } while (0)
Andrew Morton's avatar
Andrew Morton committed
324
#define	STATS_SET_FREEABLE(x, i) do { } while (0)
Linus Torvalds's avatar
Linus Torvalds committed
325
326
327
328
329
330
331
332
#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
333
334
/*
 * memory layout of objects:
Linus Torvalds's avatar
Linus Torvalds committed
335
 * 0		: objp
336
 * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
Linus Torvalds's avatar
Linus Torvalds committed
337
338
 * 		the end of an object is aligned with the end of the real
 * 		allocation. Catches writes behind the end of the allocation.
339
 * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
Linus Torvalds's avatar
Linus Torvalds committed
340
 * 		redzone word.
341
 * cachep->obj_offset: The real object.
342
343
 * 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
344
 *					[BYTES_PER_WORD long]
Linus Torvalds's avatar
Linus Torvalds committed
345
 */
346
static int obj_offset(struct kmem_cache *cachep)
Linus Torvalds's avatar
Linus Torvalds committed
347
{
348
	return cachep->obj_offset;
Linus Torvalds's avatar
Linus Torvalds committed
349
350
}

351
static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
Linus Torvalds's avatar
Linus Torvalds committed
352
353
{
	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
354
355
	return (unsigned long long*) (objp + obj_offset(cachep) -
				      sizeof(unsigned long long));
Linus Torvalds's avatar
Linus Torvalds committed
356
357
}

358
static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
Linus Torvalds's avatar
Linus Torvalds committed
359
360
361
{
	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
	if (cachep->flags & SLAB_STORE_USER)
362
		return (unsigned long long *)(objp + cachep->size -
363
					      sizeof(unsigned long long) -
David Woodhouse's avatar
David Woodhouse committed
364
					      REDZONE_ALIGN);
365
	return (unsigned long long *) (objp + cachep->size -
366
				       sizeof(unsigned long long));
Linus Torvalds's avatar
Linus Torvalds committed
367
368
}

369
static void **dbg_userword(struct kmem_cache *cachep, void *objp)
Linus Torvalds's avatar
Linus Torvalds committed
370
371
{
	BUG_ON(!(cachep->flags & SLAB_STORE_USER));
372
	return (void **)(objp + cachep->size - BYTES_PER_WORD);
Linus Torvalds's avatar
Linus Torvalds committed
373
374
375
376
}

#else

377
#define obj_offset(x)			0
378
379
#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
380
381
382
383
#define dbg_userword(cachep, objp)	({BUG(); (void **)NULL;})

#endif

384
385
#ifdef CONFIG_DEBUG_SLAB_LEAK

386
static inline bool is_store_user_clean(struct kmem_cache *cachep)
387
{
388
389
	return atomic_read(&cachep->store_user_clean) == 1;
}
390

391
392
393
394
static inline void set_store_user_clean(struct kmem_cache *cachep)
{
	atomic_set(&cachep->store_user_clean, 1);
}
395

396
397
398
399
static inline void set_store_user_dirty(struct kmem_cache *cachep)
{
	if (is_store_user_clean(cachep))
		atomic_set(&cachep->store_user_clean, 0);
400
401
402
}

#else
403
static inline void set_store_user_dirty(struct kmem_cache *cachep) {}
404
405
406

#endif

Linus Torvalds's avatar
Linus Torvalds committed
407
/*
408
409
 * 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
410
 */
411
412
413
#define	SLAB_MAX_ORDER_HI	1
#define	SLAB_MAX_ORDER_LO	0
static int slab_max_order = SLAB_MAX_ORDER_LO;
414
static bool slab_max_order_set __initdata;
Linus Torvalds's avatar
Linus Torvalds committed
415

416
417
static inline struct kmem_cache *virt_to_cache(const void *obj)
{
418
	struct page *page = virt_to_head_page(obj);
419
	return page->slab_cache;
420
421
}

422
static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
423
424
				 unsigned int idx)
{
425
	return page->s_mem + cache->size * idx;
426
427
}

428
/*
429
430
431
 * 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
432
433
434
 *   reciprocal_divide(offset, cache->reciprocal_buffer_size)
 */
static inline unsigned int obj_to_index(const struct kmem_cache *cache,
435
					const struct page *page, void *obj)
436
{
437
	u32 offset = (obj - page->s_mem);
438
	return reciprocal_divide(offset, cache->reciprocal_buffer_size);
439
440
}

441
#define BOOT_CPUCACHE_ENTRIES	1
Linus Torvalds's avatar
Linus Torvalds committed
442
/* internal cache of cache description objs */
443
static struct kmem_cache kmem_cache_boot = {
444
445
446
	.batchcount = 1,
	.limit = BOOT_CPUCACHE_ENTRIES,
	.shared = 1,
447
	.size = sizeof(struct kmem_cache),
448
	.name = "kmem_cache",
Linus Torvalds's avatar
Linus Torvalds committed
449
450
};

451
452
#define BAD_ALIEN_MAGIC 0x01020304ul

453
static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
Linus Torvalds's avatar
Linus Torvalds committed
454

455
static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
Linus Torvalds's avatar
Linus Torvalds committed
456
{
457
	return this_cpu_ptr(cachep->cpu_cache);
Linus Torvalds's avatar
Linus Torvalds committed
458
459
}

Andrew Morton's avatar
Andrew Morton committed
460
461
462
/*
 * Calculate the number of objects and left-over bytes for a given buffer size.
 */
463
464
static unsigned int cache_estimate(unsigned long gfporder, size_t buffer_size,
		unsigned long flags, size_t *left_over)
465
{
466
	unsigned int num;
467
	size_t slab_size = PAGE_SIZE << gfporder;
Linus Torvalds's avatar
Linus Torvalds committed
468

469
470
471
472
473
474
	/*
	 * 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:
	 *
	 * - @buffer_size bytes for each object
475
476
477
478
479
	 * - One freelist_idx_t for each object
	 *
	 * We don't need to consider alignment of freelist because
	 * freelist will be at the end of slab page. The objects will be
	 * at the correct alignment.
480
481
482
483
484
485
	 *
	 * 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.
	 */
486
	if (flags & (CFLGS_OBJFREELIST_SLAB | CFLGS_OFF_SLAB)) {
487
		num = slab_size / buffer_size;
488
		*left_over = slab_size % buffer_size;
489
	} else {
490
		num = slab_size / (buffer_size + sizeof(freelist_idx_t));
491
492
		*left_over = slab_size %
			(buffer_size + sizeof(freelist_idx_t));
493
	}
494
495

	return num;
Linus Torvalds's avatar
Linus Torvalds committed
496
497
}

498
#if DEBUG
499
#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
Linus Torvalds's avatar
Linus Torvalds committed
500

Andrew Morton's avatar
Andrew Morton committed
501
502
static void __slab_error(const char *function, struct kmem_cache *cachep,
			char *msg)
Linus Torvalds's avatar
Linus Torvalds committed
503
504
{
	printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
505
	       function, cachep->name, msg);
Linus Torvalds's avatar
Linus Torvalds committed
506
	dump_stack();
507
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
Linus Torvalds's avatar
Linus Torvalds committed
508
}
509
#endif
Linus Torvalds's avatar
Linus Torvalds committed
510

511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
/*
 * 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);

527
528
529
530
531
532
533
534
535
536
537
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);

538
539
540
541
542
543
544
#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.
 */
545
static DEFINE_PER_CPU(unsigned long, slab_reap_node);
546
547
548
549
550

static void init_reap_node(int cpu)
{
	int node;

551
	node = next_node(cpu_to_mem(cpu), node_online_map);
552
	if (node == MAX_NUMNODES)
553
		node = first_node(node_online_map);
554

555
	per_cpu(slab_reap_node, cpu) = node;
556
557
558
559
}

static void next_reap_node(void)
{
560
	int node = __this_cpu_read(slab_reap_node);
561
562
563
564

	node = next_node(node, node_online_map);
	if (unlikely(node >= MAX_NUMNODES))
		node = first_node(node_online_map);
565
	__this_cpu_write(slab_reap_node, node);
566
567
568
569
570
571
572
}

#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
573
574
575
576
577
578
579
/*
 * 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.
 */
580
static void start_cpu_timer(int cpu)
Linus Torvalds's avatar
Linus Torvalds committed
581
{
582
	struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
Linus Torvalds's avatar
Linus Torvalds committed
583
584
585
586
587
588

	/*
	 * When this gets called from do_initcalls via cpucache_init(),
	 * init_workqueues() has already run, so keventd will be setup
	 * at that time.
	 */
589
	if (keventd_up() && reap_work->work.func == NULL) {
590
		init_reap_node(cpu);
591
		INIT_DEFERRABLE_WORK(reap_work, cache_reap);
592
593
		schedule_delayed_work_on(cpu, reap_work,
					__round_jiffies_relative(HZ, cpu));
Linus Torvalds's avatar
Linus Torvalds committed
594
595
596
	}
}

597
static void init_arraycache(struct array_cache *ac, int limit, int batch)
Linus Torvalds's avatar
Linus Torvalds committed
598
{
599
600
	/*
	 * The array_cache structures contain pointers to free object.
Lucas De Marchi's avatar
Lucas De Marchi committed
601
	 * However, when such objects are allocated or transferred to another
602
603
604
605
	 * 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.
	 */
606
607
608
609
610
611
	kmemleak_no_scan(ac);
	if (ac) {
		ac->avail = 0;
		ac->limit = limit;
		ac->batchcount = batch;
		ac->touched = 0;
Linus Torvalds's avatar
Linus Torvalds committed
612
	}
613
614
615
616
617
}

static struct array_cache *alloc_arraycache(int node, int entries,
					    int batchcount, gfp_t gfp)
{
618
	size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache);
619
620
621
622
623
	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
624
625
}

626
static inline bool is_slab_pfmemalloc(struct page *page)
627
628
629
630
631
632
633
634
{
	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)
{
635
	struct kmem_cache_node *n = get_node(cachep, numa_mem_id());
636
	struct page *page;
637
638
639
640
641
	unsigned long flags;

	if (!pfmemalloc_active)
		return;

642
	spin_lock_irqsave(&n->list_lock, flags);
643
644
	list_for_each_entry(page, &n->slabs_full, lru)
		if (is_slab_pfmemalloc(page))
645
646
			goto out;

647
648
	list_for_each_entry(page, &n->slabs_partial, lru)
		if (is_slab_pfmemalloc(page))
649
650
			goto out;

651
652
	list_for_each_entry(page, &n->slabs_free, lru)
		if (is_slab_pfmemalloc(page))
653
654
655
656
			goto out;

	pfmemalloc_active = false;
out:
657
	spin_unlock_irqrestore(&n->list_lock, flags);
658
659
}

660
static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
661
662
663
664
665
666
667
						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))) {
668
		struct kmem_cache_node *n;
669
670
671
672
673
674
675

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

		/* The caller cannot use PFMEMALLOC objects, find another one */
676
		for (i = 0; i < ac->avail; i++) {
677
678
679
680
681
682
683
684
685
686
687
688
689
			/* 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.
		 */
690
		n = get_node(cachep, numa_mem_id());
691
		if (!list_empty(&n->slabs_free) && force_refill) {
692
			struct page *page = virt_to_head_page(objp);
693
			ClearPageSlabPfmemalloc(page);
694
695
696
697
698
699
700
701
702
703
704
705
706
			clear_obj_pfmemalloc(&objp);
			recheck_pfmemalloc_active(cachep, ac);
			return objp;
		}

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

	return objp;
}

707
708
709
710
711
712
713
714
715
716
717
718
719
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;
}

Joonsoo Kim's avatar
Joonsoo Kim committed
720
721
static noinline void *__ac_put_obj(struct kmem_cache *cachep,
			struct array_cache *ac, void *objp)
722
723
724
{
	if (unlikely(pfmemalloc_active)) {
		/* Some pfmemalloc slabs exist, check if this is one */
725
		struct page *page = virt_to_head_page(objp);
726
727
728
729
		if (PageSlabPfmemalloc(page))
			set_obj_pfmemalloc(&objp);
	}

730
731
732
733
734
735
736
737
738
	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);

739
740
741
	ac->entry[ac->avail++] = objp;
}

742
743
744
745
746
747
748
749
750
751
/*
 * 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 */
752
	int nr = min3(from->avail, max, to->limit - to->avail);
753
754
755
756
757
758
759
760
761
762
763
764

	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;
}

765
766
767
#ifndef CONFIG_NUMA

#define drain_alien_cache(cachep, alien) do { } while (0)
768
#define reap_alien(cachep, n) do { } while (0)
769

Joonsoo Kim's avatar
Joonsoo Kim committed
770
771
static inline struct alien_cache **alloc_alien_cache(int node,
						int limit, gfp_t gfp)
772
{
773
	return (struct alien_cache **)BAD_ALIEN_MAGIC;
774
775
}

Joonsoo Kim's avatar
Joonsoo Kim committed
776
static inline void free_alien_cache(struct alien_cache **ac_ptr)
777
778
779
780
781
782
783
784
785
786
787
788
789
790
{
}

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;
}

791
static inline void *____cache_alloc_node(struct kmem_cache *cachep,
792
793
794
795
796
		 gfp_t flags, int nodeid)
{
	return NULL;
}

David Rientjes's avatar
David Rientjes committed
797
798
799
800
801
static inline gfp_t gfp_exact_node(gfp_t flags)
{
	return flags;
}

802
803
#else	/* CONFIG_NUMA */

804
static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
805
static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
806

Joonsoo Kim's avatar
Joonsoo Kim committed
807
808
809
static struct alien_cache *__alloc_alien_cache(int node, int entries,
						int batch, gfp_t gfp)
{
810
	size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
Joonsoo Kim's avatar
Joonsoo Kim committed
811
812
813
814
	struct alien_cache *alc = NULL;

	alc = kmalloc_node(memsize, gfp, node);
	init_arraycache(&alc->ac, entries, batch);
815
	spin_lock_init(&alc->lock);
Joonsoo Kim's avatar
Joonsoo Kim committed
816
817
818
819
	return alc;
}

static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
820
{
Joonsoo Kim's avatar
Joonsoo Kim committed
821
	struct alien_cache **alc_ptr;
822
	size_t memsize = sizeof(void *) * nr_node_ids;
823
824
825
826
	int i;

	if (limit > 1)
		limit = 12;
Joonsoo Kim's avatar
Joonsoo Kim committed
827
828
829
830
831
832
833
834
835
836
837
838
839
	alc_ptr = kzalloc_node(memsize, gfp, node);
	if (!alc_ptr)
		return NULL;

	for_each_node(i) {
		if (i == node || !node_online(i))
			continue;
		alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
		if (!alc_ptr[i]) {
			for (i--; i >= 0; i--)
				kfree(alc_ptr[i]);
			kfree(alc_ptr);
			return NULL;
840
841
		}
	}
Joonsoo Kim's avatar
Joonsoo Kim committed
842
	return alc_ptr;
843
844
}

Joonsoo Kim's avatar
Joonsoo Kim committed
845
static void free_alien_cache(struct alien_cache **alc_ptr)
846
847
848
{
	int i;

Joonsoo Kim's avatar
Joonsoo Kim committed
849
	if (!alc_ptr)
850
851
		return;
	for_each_node(i)
Joonsoo Kim's avatar
Joonsoo Kim committed
852
853
	    kfree(alc_ptr[i]);
	kfree(alc_ptr);
854
855
}

856
static void __drain_alien_cache(struct kmem_cache *cachep,
857
858
				struct array_cache *ac, int node,
				struct list_head *list)
859
{
860
	struct kmem_cache_node *n = get_node(cachep, node);
861
862

	if (ac->avail) {
863
		spin_lock(&n->list_lock);
864
865
866
867
868
		/*
		 * 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.
		 */
869
870
		if (n->shared)
			transfer_objects(n->shared, ac, ac->limit);
871

872
		free_block(cachep, ac->entry, ac->avail, node, list);
873
		ac->avail = 0;
874
		spin_unlock(&n->list_lock);
875
876
877
	}
}

878
879
880
/*
 * Called from cache_reap() to regularly drain alien caches round robin.
 */
881
static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
882
{
883
	int node = __this_cpu_read(slab_reap_node);
884

885
	if (n->alien) {
Joonsoo Kim's avatar
Joonsoo Kim committed
886
887
888
889
890
		struct alien_cache *alc = n->alien[node];
		struct array_cache *ac;

		if (alc) {
			ac = &alc->ac;
891
			if (ac->avail && spin_trylock_irq(&alc->lock)) {
892
893
894
				LIST_HEAD(list);

				__drain_alien_cache(cachep, ac, node, &list);
895
				spin_unlock_irq(&alc->lock);
896
				slabs_destroy(cachep, &list);
Joonsoo Kim's avatar
Joonsoo Kim committed
897
			}
898
899
900
901
		}
	}
}

Andrew Morton's avatar
Andrew Morton committed
902
static void drain_alien_cache(struct kmem_cache *cachep,
Joonsoo Kim's avatar
Joonsoo Kim committed
903
				struct alien_cache **alien)
904
{
905
	int i = 0;
Joonsoo Kim's avatar
Joonsoo Kim committed
906
	struct alien_cache *alc;
907
908
909
910
	struct array_cache *ac;
	unsigned long flags;

	for_each_online_node(i) {
Joonsoo Kim's avatar
Joonsoo Kim committed
911
912
		alc = alien[i];
		if (alc) {
913
914
			LIST_HEAD(list);

Joonsoo Kim's avatar
Joonsoo Kim committed
915
			ac = &alc->ac;
916
			spin_lock_irqsave(&alc->lock, flags);
917
			__drain_alien_cache(cachep, ac, i, &list);
918
			spin_unlock_irqrestore(&alc->lock, flags);
919
			slabs_destroy(cachep, &list);
920
921
922
		}
	}
}
923

924
925
static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
				int node, int page_node)
926
{
927
	struct kmem_cache_node *n;
Joonsoo Kim's avatar
Joonsoo Kim committed
928
929
	struct alien_cache *alien = NULL;
	struct array_cache *ac;
930
	LIST_HEAD(list);
931

932
	n = get_node(cachep, node);
933
	STATS_INC_NODEFREES(cachep);
934
935
	if (n->alien && n->alien[page_node]) {
		alien = n->alien[page_node];
Joonsoo Kim's avatar
Joonsoo Kim committed
936
		ac = &alien->ac;
937
		spin_lock(&alien->lock);
Joonsoo Kim's avatar
Joonsoo Kim committed
938
		if (unlikely(ac->avail == ac->limit)) {
939
			STATS_INC_ACOVERFLOW(cachep);
940
			__drain_alien_cache(cachep, ac, page_node, &list);
941
		}
Joonsoo Kim's avatar
Joonsoo Kim committed
942
		ac_put_obj(cachep, ac, objp);
943
		spin_unlock(&alien->lock);
944
		slabs_destroy(cachep, &list);
945
	} else {
946
		n = get_node(cachep, page_node);
947
		spin_lock(&n->list_lock);
948
		free_block(cachep, &objp, 1, page_node, &list);
949
		spin_unlock(&n->list_lock);
950
		slabs_destroy(cachep, &list);
951
952
953
	}
	return 1;
}
954
955
956
957
958
959
960
961
962
963
964
965
966
967

static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
	int page_node = page_to_nid(virt_to_page(objp));
	int node = numa_mem_id();
	/*
	 * Make sure we are not freeing a object from another node to the array
	 * cache on this cpu.
	 */
	if (likely(node == page_node))
		return 0;

	return __cache_free_alien(cachep, objp, node, page_node);
}
David Rientjes's avatar
David Rientjes committed
968
969

/*
970
971
 * Construct gfp mask to allocate from a specific node but do not direct reclaim
 * or warn about failures. kswapd may still wake to reclaim in the background.
David Rientjes's avatar
David Rientjes committed
972
973
974
 */
static inline gfp_t gfp_exact_node(gfp_t flags)
{
975
	return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM;
David Rientjes's avatar
David Rientjes committed
976
}
977
978
#endif

979
/*
980
 * Allocates and initializes node for a node on each slab cache, used for
981
 * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
982
 * will be allocated off-node since memory is not yet online for the new node.
983
 * When hotplugging memory or a cpu, existing node are not replaced if
984
985
 * already in use.
 *
986
 * Must hold slab_mutex.
987
 */
988
static int init_cache_node_node(int node)
989
990
{
	struct kmem_cache *cachep;
991
	struct kmem_cache_node *n;
992
	const size_t memsize = sizeof(struct kmem_cache_node);
993

994
	list_for_each_entry(cachep, &slab_caches, list) {
995
		/*
996
		 * Set up the kmem_cache_node for cpu before we can
997
998
999
		 * begin anything. Make sure some other cpu on this
		 * node has not already allocated this
		 */
1000
1001
		n = get_node(cachep, node);
		if (!n) {
1002
1003
			n = kmalloc_node(memsize, GFP_KERNEL, node);
			if (!n)
1004
				return -ENOMEM;
1005
			kmem_cache_node_init(n);
1006
1007
			n->next_reap = jiffies + REAPTIMEOUT_NODE +
			    ((unsigned long)cachep) % REAPTIMEOUT_NODE;
1008
1009

			/*
1010
1011
			 * The kmem_cache_nodes don't come and go as CPUs
			 * come and go.  slab_mutex is sufficient
1012
1013
			 * protection here.
			 */
1014
			cachep->node[node] = n;
1015
1016
		}

1017
1018
		spin_lock_irq(&n->list_lock);
		n->free_limit =
1019
1020
			(1 + nr_cpus_node(node)) *
			cachep->batchcount + cachep->num;
1021
		spin_unlock_irq(&n->list_lock);
1022
1023
1024
1025
	}
	return 0;
}

1026
1027
1028
1029
1030
1031
static inline int slabs_tofree(struct kmem_cache *cachep,
						struct kmem_cache_node *n)
{
	return (n->free_objects + cachep->num - 1) / cachep->num;
}

1032
static void cpuup_canceled(long cpu)
1033
1034
{
	struct kmem_cache *cachep;
1035
	struct kmem_cache_node *n = NULL;
1036
	int node = cpu_to_mem(cpu);
1037
	const struct cpumask *mask = cpumask_of_node(node);
1038

1039
	list_for_each_entry(cachep, &slab_caches, list) {
1040
1041
		struct array_cache *nc;
		struct array_cache *shared;
Joonsoo Kim's avatar
Joonsoo Kim committed
1042
		struct alien_cache **alien;
1043
		LIST_HEAD(list);
1044

1045
		n = get_node(cachep, node);
1046
		if (!n)
1047
			continue;
1048

1049
		spin_lock_irq(&n->list_lock);
1050

1051
1052
		/* Free limit for this kmem_cache_node */
		n->free_limit -= cachep->batchcount;
1053
1054
1055
1056

		/* cpu is dead; no one can alloc from it. */
		nc = per_cpu_ptr(cachep->cpu_cache, cpu);
		if (nc) {
1057
			free_block(cachep, nc->entry, nc->avail, node, &list);
1058
1059
			nc->avail = 0;
		}
1060

1061
		if (!cpumask_empty(mask)) {
1062
			spin_unlock_irq(&n->list_lock);
1063
			goto free_slab;
1064
1065
		}