slub.c 90.1 KB
Newer Older
Christoph Lameter's avatar
Christoph Lameter 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
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
/*
 * SLUB: A slab allocator that limits cache line use instead of queuing
 * objects in per cpu and per node lists.
 *
 * The allocator synchronizes using per slab locks and only
 * uses a centralized lock to manage a pool of partial slabs.
 *
 * (C) 2007 SGI, Christoph Lameter <clameter@sgi.com>
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <linux/bit_spinlock.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
#include <linux/ctype.h>
#include <linux/kallsyms.h>

/*
 * Lock order:
 *   1. slab_lock(page)
 *   2. slab->list_lock
 *
 *   The slab_lock protects operations on the object of a particular
 *   slab and its metadata in the page struct. If the slab lock
 *   has been taken then no allocations nor frees can be performed
 *   on the objects in the slab nor can the slab be added or removed
 *   from the partial or full lists since this would mean modifying
 *   the page_struct of the slab.
 *
 *   The list_lock protects the partial and full list on each node and
 *   the partial slab counter. If taken then no new slabs may be added or
 *   removed from the lists nor make the number of partial slabs be modified.
 *   (Note that the total number of slabs is an atomic value that may be
 *   modified without taking the list lock).
 *
 *   The list_lock is a centralized lock and thus we avoid taking it as
 *   much as possible. As long as SLUB does not have to handle partial
 *   slabs, operations can continue without any centralized lock. F.e.
 *   allocating a long series of objects that fill up slabs does not require
 *   the list lock.
 *
 *   The lock order is sometimes inverted when we are trying to get a slab
 *   off a list. We take the list_lock and then look for a page on the list
 *   to use. While we do that objects in the slabs may be freed. We can
 *   only operate on the slab if we have also taken the slab_lock. So we use
 *   a slab_trylock() on the slab. If trylock was successful then no frees
 *   can occur anymore and we can use the slab for allocations etc. If the
 *   slab_trylock() does not succeed then frees are in progress in the slab and
 *   we must stay away from it for a while since we may cause a bouncing
 *   cacheline if we try to acquire the lock. So go onto the next slab.
 *   If all pages are busy then we may allocate a new slab instead of reusing
 *   a partial slab. A new slab has noone operating on it and thus there is
 *   no danger of cacheline contention.
 *
 *   Interrupts are disabled during allocation and deallocation in order to
 *   make the slab allocator safe to use in the context of an irq. In addition
 *   interrupts are disabled to ensure that the processor does not change
 *   while handling per_cpu slabs, due to kernel preemption.
 *
 * SLUB assigns one slab for allocation to each processor.
 * Allocations only occur from these slabs called cpu slabs.
 *
Christoph Lameter's avatar
Christoph Lameter committed
69
70
 * Slabs with free elements are kept on a partial list and during regular
 * operations no list for full slabs is used. If an object in a full slab is
Christoph Lameter's avatar
Christoph Lameter committed
71
 * freed then the slab will show up again on the partial lists.
Christoph Lameter's avatar
Christoph Lameter committed
72
73
 * We track full slabs for debugging purposes though because otherwise we
 * cannot scan all objects.
Christoph Lameter's avatar
Christoph Lameter committed
74
75
76
77
78
79
80
 *
 * Slabs are freed when they become empty. Teardown and setup is
 * minimal so we rely on the page allocators per cpu caches for
 * fast frees and allocs.
 *
 * Overloading of page flags that are otherwise used for LRU management.
 *
81
82
83
84
85
86
87
88
89
90
91
92
 * PageActive 		The slab is frozen and exempt from list processing.
 * 			This means that the slab is dedicated to a purpose
 * 			such as satisfying allocations for a specific
 * 			processor. Objects may be freed in the slab while
 * 			it is frozen but slab_free will then skip the usual
 * 			list operations. It is up to the processor holding
 * 			the slab to integrate the slab into the slab lists
 * 			when the slab is no longer needed.
 *
 * 			One use of this flag is to mark slabs that are
 * 			used for allocations. Then such a slab becomes a cpu
 * 			slab. The cpu slab may be equipped with an additional
93
94
95
 * 			lockless_freelist that allows lockless access to
 * 			free objects in addition to the regular freelist
 * 			that requires the slab lock.
Christoph Lameter's avatar
Christoph Lameter committed
96
97
98
 *
 * PageError		Slab requires special handling due to debug
 * 			options set. This moves	slab handling out of
99
 * 			the fast path and disables lockless freelists.
Christoph Lameter's avatar
Christoph Lameter committed
100
101
 */

102
103
104
105
106
107
108
109
#define FROZEN (1 << PG_active)

#ifdef CONFIG_SLUB_DEBUG
#define SLABDEBUG (1 << PG_error)
#else
#define SLABDEBUG 0
#endif

110
111
static inline int SlabFrozen(struct page *page)
{
112
	return page->flags & FROZEN;
113
114
115
116
}

static inline void SetSlabFrozen(struct page *page)
{
117
	page->flags |= FROZEN;
118
119
120
121
}

static inline void ClearSlabFrozen(struct page *page)
{
122
	page->flags &= ~FROZEN;
123
124
}

125
126
static inline int SlabDebug(struct page *page)
{
127
	return page->flags & SLABDEBUG;
128
129
130
131
}

static inline void SetSlabDebug(struct page *page)
{
132
	page->flags |= SLABDEBUG;
133
134
135
136
}

static inline void ClearSlabDebug(struct page *page)
{
137
	page->flags &= ~SLABDEBUG;
138
139
}

Christoph Lameter's avatar
Christoph Lameter committed
140
141
142
143
144
/*
 * Issues still to be resolved:
 *
 * - The per cpu array is updated for each new slab and and is a remote
 *   cacheline for most nodes. This could become a bouncing cacheline given
Christoph Lameter's avatar
Christoph Lameter committed
145
146
 *   enough frequent updates. There are 16 pointers in a cacheline, so at
 *   max 16 cpus could compete for the cacheline which may be okay.
Christoph Lameter's avatar
Christoph Lameter committed
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
 *
 * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
 *
 * - Variable sizing of the per node arrays
 */

/* Enable to test recovery from slab corruption on boot */
#undef SLUB_RESILIENCY_TEST

#if PAGE_SHIFT <= 12

/*
 * Small page size. Make sure that we do not fragment memory
 */
#define DEFAULT_MAX_ORDER 1
#define DEFAULT_MIN_OBJECTS 4

#else

/*
 * Large page machines are customarily able to handle larger
 * page orders.
 */
#define DEFAULT_MAX_ORDER 2
#define DEFAULT_MIN_OBJECTS 8

#endif

175
176
177
178
/*
 * Mininum number of partial slabs. These will be left on the partial
 * lists even if they are empty. kmem_cache_shrink may reclaim them.
 */
Christoph Lameter's avatar
Christoph Lameter committed
179
180
#define MIN_PARTIAL 2

181
182
183
184
185
186
187
/*
 * Maximum number of desirable partial slabs.
 * The existence of more partial slabs makes kmem_cache_shrink
 * sort the partial list by the number of objects in the.
 */
#define MAX_PARTIAL 10

Christoph Lameter's avatar
Christoph Lameter committed
188
189
#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
				SLAB_POISON | SLAB_STORE_USER)
Christoph Lameter's avatar
Christoph Lameter committed
190

Christoph Lameter's avatar
Christoph Lameter committed
191
192
193
194
195
196
197
198
199
200
/*
 * Set of flags that will prevent slab merging
 */
#define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
		SLAB_TRACE | SLAB_DESTROY_BY_RCU)

#define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
		SLAB_CACHE_DMA)

#ifndef ARCH_KMALLOC_MINALIGN
201
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
Christoph Lameter's avatar
Christoph Lameter committed
202
203
204
#endif

#ifndef ARCH_SLAB_MINALIGN
205
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
Christoph Lameter's avatar
Christoph Lameter committed
206
207
#endif

208
209
210
211
212
/*
 * The page->inuse field is 16 bit thus we have this limitation
 */
#define MAX_OBJECTS_PER_SLAB 65535

Christoph Lameter's avatar
Christoph Lameter committed
213
/* Internal SLUB flags */
214
215
#define __OBJECT_POISON		0x80000000 /* Poison object */
#define __SYSFS_ADD_DEFERRED	0x40000000 /* Not yet visible via sysfs */
Christoph Lameter's avatar
Christoph Lameter committed
216

217
218
219
220
221
/* Not all arches define cache_line_size */
#ifndef cache_line_size
#define cache_line_size()	L1_CACHE_BYTES
#endif

Christoph Lameter's avatar
Christoph Lameter committed
222
223
224
225
226
227
228
229
230
static int kmem_size = sizeof(struct kmem_cache);

#ifdef CONFIG_SMP
static struct notifier_block slab_notifier;
#endif

static enum {
	DOWN,		/* No slab functionality available */
	PARTIAL,	/* kmem_cache_open() works but kmalloc does not */
Christoph Lameter's avatar
Christoph Lameter committed
231
	UP,		/* Everything works but does not show up in sysfs */
Christoph Lameter's avatar
Christoph Lameter committed
232
233
234
235
236
	SYSFS		/* Sysfs up */
} slab_state = DOWN;

/* A list of all slab caches on the system */
static DECLARE_RWSEM(slub_lock);
Adrian Bunk's avatar
Adrian Bunk committed
237
static LIST_HEAD(slab_caches);
Christoph Lameter's avatar
Christoph Lameter committed
238

239
240
241
242
243
244
245
246
247
248
249
250
/*
 * Tracking user of a slab.
 */
struct track {
	void *addr;		/* Called from address */
	int cpu;		/* Was running on cpu */
	int pid;		/* Pid context */
	unsigned long when;	/* When did the operation occur */
};

enum track_item { TRACK_ALLOC, TRACK_FREE };

251
#if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)
Christoph Lameter's avatar
Christoph Lameter committed
252
253
254
255
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
static void sysfs_slab_remove(struct kmem_cache *);
#else
256
257
258
259
static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
							{ return 0; }
static inline void sysfs_slab_remove(struct kmem_cache *s) {}
Christoph Lameter's avatar
Christoph Lameter committed
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
#endif

/********************************************************************
 * 			Core slab cache functions
 *******************************************************************/

int slab_is_available(void)
{
	return slab_state >= UP;
}

static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
{
#ifdef CONFIG_NUMA
	return s->node[node];
#else
	return &s->local_node;
#endif
}

280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
static inline int check_valid_pointer(struct kmem_cache *s,
				struct page *page, const void *object)
{
	void *base;

	if (!object)
		return 1;

	base = page_address(page);
	if (object < base || object >= base + s->objects * s->size ||
		(object - base) % s->size) {
		return 0;
	}

	return 1;
}

297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
/*
 * Slow version of get and set free pointer.
 *
 * This version requires touching the cache lines of kmem_cache which
 * we avoid to do in the fast alloc free paths. There we obtain the offset
 * from the page struct.
 */
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
	return *(void **)(object + s->offset);
}

static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
	*(void **)(object + s->offset) = fp;
}

/* Loop over all objects in a slab */
#define for_each_object(__p, __s, __addr) \
	for (__p = (__addr); __p < (__addr) + (__s)->objects * (__s)->size;\
			__p += (__s)->size)

/* Scan freelist */
#define for_each_free_object(__p, __s, __free) \
	for (__p = (__free); __p; __p = get_freepointer((__s), __p))

/* Determine object index from a given position */
static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
{
	return (p - addr) / s->size;
}

329
330
331
332
#ifdef CONFIG_SLUB_DEBUG
/*
 * Debug settings:
 */
333
334
335
#ifdef CONFIG_SLUB_DEBUG_ON
static int slub_debug = DEBUG_DEFAULT_FLAGS;
#else
336
static int slub_debug;
337
#endif
338
339
340

static char *slub_debug_slabs;

Christoph Lameter's avatar
Christoph Lameter committed
341
342
343
344
345
346
347
348
349
350
351
352
353
/*
 * Object debugging
 */
static void print_section(char *text, u8 *addr, unsigned int length)
{
	int i, offset;
	int newline = 1;
	char ascii[17];

	ascii[16] = 0;

	for (i = 0; i < length; i++) {
		if (newline) {
354
			printk(KERN_ERR "%8s 0x%p: ", text, addr + i);
Christoph Lameter's avatar
Christoph Lameter committed
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
			newline = 0;
		}
		printk(" %02x", addr[i]);
		offset = i % 16;
		ascii[offset] = isgraph(addr[i]) ? addr[i] : '.';
		if (offset == 15) {
			printk(" %s\n",ascii);
			newline = 1;
		}
	}
	if (!newline) {
		i %= 16;
		while (i < 16) {
			printk("   ");
			ascii[i] = ' ';
			i++;
		}
		printk(" %s\n", ascii);
	}
}

static struct track *get_track(struct kmem_cache *s, void *object,
	enum track_item alloc)
{
	struct track *p;

	if (s->offset)
		p = object + s->offset + sizeof(void *);
	else
		p = object + s->inuse;

	return p + alloc;
}

static void set_track(struct kmem_cache *s, void *object,
				enum track_item alloc, void *addr)
{
	struct track *p;

	if (s->offset)
		p = object + s->offset + sizeof(void *);
	else
		p = object + s->inuse;

	p += alloc;
	if (addr) {
		p->addr = addr;
		p->cpu = smp_processor_id();
		p->pid = current ? current->pid : -1;
		p->when = jiffies;
	} else
		memset(p, 0, sizeof(struct track));
}

static void init_tracking(struct kmem_cache *s, void *object)
{
411
412
413
414
415
	if (!(s->flags & SLAB_STORE_USER))
		return;

	set_track(s, object, TRACK_FREE, NULL);
	set_track(s, object, TRACK_ALLOC, NULL);
Christoph Lameter's avatar
Christoph Lameter committed
416
417
418
419
420
421
422
}

static void print_track(const char *s, struct track *t)
{
	if (!t->addr)
		return;

423
	printk(KERN_ERR "INFO: %s in ", s);
Christoph Lameter's avatar
Christoph Lameter committed
424
	__print_symbol("%s", (unsigned long)t->addr);
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
	printk(" age=%lu cpu=%u pid=%d\n", jiffies - t->when, t->cpu, t->pid);
}

static void print_tracking(struct kmem_cache *s, void *object)
{
	if (!(s->flags & SLAB_STORE_USER))
		return;

	print_track("Allocated", get_track(s, object, TRACK_ALLOC));
	print_track("Freed", get_track(s, object, TRACK_FREE));
}

static void print_page_info(struct page *page)
{
	printk(KERN_ERR "INFO: Slab 0x%p used=%u fp=0x%p flags=0x%04lx\n",
		page, page->inuse, page->freelist, page->flags);

}

static void slab_bug(struct kmem_cache *s, char *fmt, ...)
{
	va_list args;
	char buf[100];

	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);
	printk(KERN_ERR "========================================"
			"=====================================\n");
	printk(KERN_ERR "BUG %s: %s\n", s->name, buf);
	printk(KERN_ERR "----------------------------------------"
			"-------------------------------------\n\n");
Christoph Lameter's avatar
Christoph Lameter committed
457
458
}

459
460
461
462
463
464
465
466
467
468
469
470
static void slab_fix(struct kmem_cache *s, char *fmt, ...)
{
	va_list args;
	char buf[100];

	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);
	printk(KERN_ERR "FIX %s: %s\n", s->name, buf);
}

static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
Christoph Lameter's avatar
Christoph Lameter committed
471
472
{
	unsigned int off;	/* Offset of last byte */
473
474
475
476
477
478
479
480
481
482
483
484
485
	u8 *addr = page_address(page);

	print_tracking(s, p);

	print_page_info(page);

	printk(KERN_ERR "INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
			p, p - addr, get_freepointer(s, p));

	if (p > addr + 16)
		print_section("Bytes b4", p - 16, 16);

	print_section("Object", p, min(s->objsize, 128));
Christoph Lameter's avatar
Christoph Lameter committed
486
487
488
489
490
491
492
493
494
495

	if (s->flags & SLAB_RED_ZONE)
		print_section("Redzone", p + s->objsize,
			s->inuse - s->objsize);

	if (s->offset)
		off = s->offset + sizeof(void *);
	else
		off = s->inuse;

496
	if (s->flags & SLAB_STORE_USER)
Christoph Lameter's avatar
Christoph Lameter committed
497
498
499
500
		off += 2 * sizeof(struct track);

	if (off != s->size)
		/* Beginning of the filler is the free pointer */
501
502
503
		print_section("Padding", p + off, s->size - off);

	dump_stack();
Christoph Lameter's avatar
Christoph Lameter committed
504
505
506
507
508
}

static void object_err(struct kmem_cache *s, struct page *page,
			u8 *object, char *reason)
{
509
510
	slab_bug(s, reason);
	print_trailer(s, page, object);
Christoph Lameter's avatar
Christoph Lameter committed
511
512
}

513
static void slab_err(struct kmem_cache *s, struct page *page, char *fmt, ...)
Christoph Lameter's avatar
Christoph Lameter committed
514
515
516
517
{
	va_list args;
	char buf[100];

518
519
	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
Christoph Lameter's avatar
Christoph Lameter committed
520
	va_end(args);
521
522
	slab_bug(s, fmt);
	print_page_info(page);
Christoph Lameter's avatar
Christoph Lameter committed
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
	dump_stack();
}

static void init_object(struct kmem_cache *s, void *object, int active)
{
	u8 *p = object;

	if (s->flags & __OBJECT_POISON) {
		memset(p, POISON_FREE, s->objsize - 1);
		p[s->objsize -1] = POISON_END;
	}

	if (s->flags & SLAB_RED_ZONE)
		memset(p + s->objsize,
			active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE,
			s->inuse - s->objsize);
}

541
static u8 *check_bytes(u8 *start, unsigned int value, unsigned int bytes)
Christoph Lameter's avatar
Christoph Lameter committed
542
543
544
{
	while (bytes) {
		if (*start != (u8)value)
545
			return start;
Christoph Lameter's avatar
Christoph Lameter committed
546
547
548
		start++;
		bytes--;
	}
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
	return NULL;
}

static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
						void *from, void *to)
{
	slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
	memset(from, data, to - from);
}

static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
			u8 *object, char *what,
			u8* start, unsigned int value, unsigned int bytes)
{
	u8 *fault;
	u8 *end;

	fault = check_bytes(start, value, bytes);
	if (!fault)
		return 1;

	end = start + bytes;
	while (end > fault && end[-1] == value)
		end--;

	slab_bug(s, "%s overwritten", what);
	printk(KERN_ERR "INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n",
					fault, end - 1, fault[0], value);
	print_trailer(s, page, object);

	restore_bytes(s, what, value, fault, end);
	return 0;
Christoph Lameter's avatar
Christoph Lameter committed
581
582
583
584
585
586
587
588
589
}

/*
 * Object layout:
 *
 * object address
 * 	Bytes of the object to be managed.
 * 	If the freepointer may overlay the object then the free
 * 	pointer is the first word of the object.
Christoph Lameter's avatar
Christoph Lameter committed
590
 *
Christoph Lameter's avatar
Christoph Lameter committed
591
592
593
594
595
 * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
 * 	0xa5 (POISON_END)
 *
 * object + s->objsize
 * 	Padding to reach word boundary. This is also used for Redzoning.
Christoph Lameter's avatar
Christoph Lameter committed
596
597
598
 * 	Padding is extended by another word if Redzoning is enabled and
 * 	objsize == inuse.
 *
Christoph Lameter's avatar
Christoph Lameter committed
599
600
601
602
 * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
 * 	0xcc (RED_ACTIVE) for objects in use.
 *
 * object + s->inuse
Christoph Lameter's avatar
Christoph Lameter committed
603
604
 * 	Meta data starts here.
 *
Christoph Lameter's avatar
Christoph Lameter committed
605
606
 * 	A. Free pointer (if we cannot overwrite object on free)
 * 	B. Tracking data for SLAB_STORE_USER
Christoph Lameter's avatar
Christoph Lameter committed
607
608
609
610
611
 * 	C. Padding to reach required alignment boundary or at mininum
 * 		one word if debuggin is on to be able to detect writes
 * 		before the word boundary.
 *
 *	Padding is done using 0x5a (POISON_INUSE)
Christoph Lameter's avatar
Christoph Lameter committed
612
613
 *
 * object + s->size
Christoph Lameter's avatar
Christoph Lameter committed
614
 * 	Nothing is used beyond s->size.
Christoph Lameter's avatar
Christoph Lameter committed
615
 *
Christoph Lameter's avatar
Christoph Lameter committed
616
617
 * If slabcaches are merged then the objsize and inuse boundaries are mostly
 * ignored. And therefore no slab options that rely on these boundaries
Christoph Lameter's avatar
Christoph Lameter committed
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
 * may be used with merged slabcaches.
 */

static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
{
	unsigned long off = s->inuse;	/* The end of info */

	if (s->offset)
		/* Freepointer is placed after the object. */
		off += sizeof(void *);

	if (s->flags & SLAB_STORE_USER)
		/* We also have user information there */
		off += 2 * sizeof(struct track);

	if (s->size == off)
		return 1;

636
637
	return check_bytes_and_report(s, page, p, "Object padding",
				p + off, POISON_INUSE, s->size - off);
Christoph Lameter's avatar
Christoph Lameter committed
638
639
640
641
}

static int slab_pad_check(struct kmem_cache *s, struct page *page)
{
642
643
644
645
646
	u8 *start;
	u8 *fault;
	u8 *end;
	int length;
	int remainder;
Christoph Lameter's avatar
Christoph Lameter committed
647
648
649
650

	if (!(s->flags & SLAB_POISON))
		return 1;

651
652
	start = page_address(page);
	end = start + (PAGE_SIZE << s->order);
Christoph Lameter's avatar
Christoph Lameter committed
653
	length = s->objects * s->size;
654
	remainder = end - (start + length);
Christoph Lameter's avatar
Christoph Lameter committed
655
656
657
	if (!remainder)
		return 1;

658
659
660
661
662
663
664
665
666
667
668
	fault = check_bytes(start + length, POISON_INUSE, remainder);
	if (!fault)
		return 1;
	while (end > fault && end[-1] == POISON_INUSE)
		end--;

	slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
	print_section("Padding", start, length);

	restore_bytes(s, "slab padding", POISON_INUSE, start, end);
	return 0;
Christoph Lameter's avatar
Christoph Lameter committed
669
670
671
672
673
674
675
676
677
678
679
680
}

static int check_object(struct kmem_cache *s, struct page *page,
					void *object, int active)
{
	u8 *p = object;
	u8 *endobject = object + s->objsize;

	if (s->flags & SLAB_RED_ZONE) {
		unsigned int red =
			active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE;

681
682
		if (!check_bytes_and_report(s, page, object, "Redzone",
			endobject, red, s->inuse - s->objsize))
Christoph Lameter's avatar
Christoph Lameter committed
683
684
			return 0;
	} else {
685
686
687
		if ((s->flags & SLAB_POISON) && s->objsize < s->inuse)
			check_bytes_and_report(s, page, p, "Alignment padding", endobject,
				POISON_INUSE, s->inuse - s->objsize);
Christoph Lameter's avatar
Christoph Lameter committed
688
689
690
691
	}

	if (s->flags & SLAB_POISON) {
		if (!active && (s->flags & __OBJECT_POISON) &&
692
693
694
695
			(!check_bytes_and_report(s, page, p, "Poison", p,
					POISON_FREE, s->objsize - 1) ||
			 !check_bytes_and_report(s, page, p, "Poison",
			 	p + s->objsize -1, POISON_END, 1)))
Christoph Lameter's avatar
Christoph Lameter committed
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
			return 0;
		/*
		 * check_pad_bytes cleans up on its own.
		 */
		check_pad_bytes(s, page, p);
	}

	if (!s->offset && active)
		/*
		 * Object and freepointer overlap. Cannot check
		 * freepointer while object is allocated.
		 */
		return 1;

	/* Check free pointer validity */
	if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
		object_err(s, page, p, "Freepointer corrupt");
		/*
		 * No choice but to zap it and thus loose the remainder
		 * of the free objects in this slab. May cause
Christoph Lameter's avatar
Christoph Lameter committed
716
		 * another error because the object count is now wrong.
Christoph Lameter's avatar
Christoph Lameter committed
717
718
719
720
721
722
723
724
725
726
727
728
		 */
		set_freepointer(s, p, NULL);
		return 0;
	}
	return 1;
}

static int check_slab(struct kmem_cache *s, struct page *page)
{
	VM_BUG_ON(!irqs_disabled());

	if (!PageSlab(page)) {
729
		slab_err(s, page, "Not a valid slab page");
Christoph Lameter's avatar
Christoph Lameter committed
730
731
732
		return 0;
	}
	if (page->offset * sizeof(void *) != s->offset) {
733
734
		slab_err(s, page, "Corrupted offset %lu",
			(unsigned long)(page->offset * sizeof(void *)));
Christoph Lameter's avatar
Christoph Lameter committed
735
736
737
		return 0;
	}
	if (page->inuse > s->objects) {
738
739
		slab_err(s, page, "inuse %u > max %u",
			s->name, page->inuse, s->objects);
Christoph Lameter's avatar
Christoph Lameter committed
740
741
742
743
744
745
746
747
		return 0;
	}
	/* Slab_pad_check fixes things up after itself */
	slab_pad_check(s, page);
	return 1;
}

/*
Christoph Lameter's avatar
Christoph Lameter committed
748
749
 * Determine if a certain object on a page is on the freelist. Must hold the
 * slab lock to guarantee that the chains are in a consistent state.
Christoph Lameter's avatar
Christoph Lameter committed
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
 */
static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
{
	int nr = 0;
	void *fp = page->freelist;
	void *object = NULL;

	while (fp && nr <= s->objects) {
		if (fp == search)
			return 1;
		if (!check_valid_pointer(s, page, fp)) {
			if (object) {
				object_err(s, page, object,
					"Freechain corrupt");
				set_freepointer(s, object, NULL);
				break;
			} else {
767
				slab_err(s, page, "Freepointer corrupt");
Christoph Lameter's avatar
Christoph Lameter committed
768
769
				page->freelist = NULL;
				page->inuse = s->objects;
770
				slab_fix(s, "Freelist cleared");
Christoph Lameter's avatar
Christoph Lameter committed
771
772
773
774
775
776
777
778
779
780
				return 0;
			}
			break;
		}
		object = fp;
		fp = get_freepointer(s, object);
		nr++;
	}

	if (page->inuse != s->objects - nr) {
781
		slab_err(s, page, "Wrong object count. Counter is %d but "
782
			"counted were %d", page->inuse, s->objects - nr);
Christoph Lameter's avatar
Christoph Lameter committed
783
		page->inuse = s->objects - nr;
784
		slab_fix(s, "Object count adjusted.");
Christoph Lameter's avatar
Christoph Lameter committed
785
786
787
788
	}
	return search == NULL;
}

Christoph Lameter's avatar
Christoph Lameter committed
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
static void trace(struct kmem_cache *s, struct page *page, void *object, int alloc)
{
	if (s->flags & SLAB_TRACE) {
		printk(KERN_INFO "TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
			s->name,
			alloc ? "alloc" : "free",
			object, page->inuse,
			page->freelist);

		if (!alloc)
			print_section("Object", (void *)object, s->objsize);

		dump_stack();
	}
}

805
/*
Christoph Lameter's avatar
Christoph Lameter committed
806
 * Tracking of fully allocated slabs for debugging purposes.
807
 */
Christoph Lameter's avatar
Christoph Lameter committed
808
static void add_full(struct kmem_cache_node *n, struct page *page)
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
{
	spin_lock(&n->list_lock);
	list_add(&page->lru, &n->full);
	spin_unlock(&n->list_lock);
}

static void remove_full(struct kmem_cache *s, struct page *page)
{
	struct kmem_cache_node *n;

	if (!(s->flags & SLAB_STORE_USER))
		return;

	n = get_node(s, page_to_nid(page));

	spin_lock(&n->list_lock);
	list_del(&page->lru);
	spin_unlock(&n->list_lock);
}

Christoph Lameter's avatar
Christoph Lameter committed
829
830
831
832
833
834
835
836
837
838
839
840
static void setup_object_debug(struct kmem_cache *s, struct page *page,
								void *object)
{
	if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
		return;

	init_object(s, object, 0);
	init_tracking(s, object);
}

static int alloc_debug_processing(struct kmem_cache *s, struct page *page,
						void *object, void *addr)
Christoph Lameter's avatar
Christoph Lameter committed
841
842
843
844
845
{
	if (!check_slab(s, page))
		goto bad;

	if (object && !on_freelist(s, page, object)) {
846
		object_err(s, page, object, "Object already allocated");
847
		goto bad;
Christoph Lameter's avatar
Christoph Lameter committed
848
849
850
851
	}

	if (!check_valid_pointer(s, page, object)) {
		object_err(s, page, object, "Freelist Pointer check fails");
852
		goto bad;
Christoph Lameter's avatar
Christoph Lameter committed
853
854
	}

Christoph Lameter's avatar
Christoph Lameter committed
855
	if (object && !check_object(s, page, object, 0))
Christoph Lameter's avatar
Christoph Lameter committed
856
857
		goto bad;

Christoph Lameter's avatar
Christoph Lameter committed
858
859
860
861
862
	/* Success perform special debug activities for allocs */
	if (s->flags & SLAB_STORE_USER)
		set_track(s, object, TRACK_ALLOC, addr);
	trace(s, page, object, 1);
	init_object(s, object, 1);
Christoph Lameter's avatar
Christoph Lameter committed
863
	return 1;
Christoph Lameter's avatar
Christoph Lameter committed
864

Christoph Lameter's avatar
Christoph Lameter committed
865
866
867
868
869
bad:
	if (PageSlab(page)) {
		/*
		 * If this is a slab page then lets do the best we can
		 * to avoid issues in the future. Marking all objects
Christoph Lameter's avatar
Christoph Lameter committed
870
		 * as used avoids touching the remaining objects.
Christoph Lameter's avatar
Christoph Lameter committed
871
		 */
872
		slab_fix(s, "Marking all objects used");
Christoph Lameter's avatar
Christoph Lameter committed
873
874
875
876
877
878
879
880
		page->inuse = s->objects;
		page->freelist = NULL;
		/* Fix up fields that may be corrupted */
		page->offset = s->offset / sizeof(void *);
	}
	return 0;
}

Christoph Lameter's avatar
Christoph Lameter committed
881
882
static int free_debug_processing(struct kmem_cache *s, struct page *page,
						void *object, void *addr)
Christoph Lameter's avatar
Christoph Lameter committed
883
884
885
886
887
{
	if (!check_slab(s, page))
		goto fail;

	if (!check_valid_pointer(s, page, object)) {
888
		slab_err(s, page, "Invalid object pointer 0x%p", object);
Christoph Lameter's avatar
Christoph Lameter committed
889
890
891
892
		goto fail;
	}

	if (on_freelist(s, page, object)) {
893
		object_err(s, page, object, "Object already free");
Christoph Lameter's avatar
Christoph Lameter committed
894
895
896
897
898
899
900
901
		goto fail;
	}

	if (!check_object(s, page, object, 1))
		return 0;

	if (unlikely(s != page->slab)) {
		if (!PageSlab(page))
902
903
			slab_err(s, page, "Attempt to free object(0x%p) "
				"outside of slab", object);
Christoph Lameter's avatar
Christoph Lameter committed
904
		else
905
		if (!page->slab) {
Christoph Lameter's avatar
Christoph Lameter committed
906
			printk(KERN_ERR
907
				"SLUB <none>: no slab for object 0x%p.\n",
Christoph Lameter's avatar
Christoph Lameter committed
908
						object);
909
910
			dump_stack();
		}
Christoph Lameter's avatar
Christoph Lameter committed
911
		else
912
913
			object_err(s, page, object,
					"page slab pointer corrupt.");
Christoph Lameter's avatar
Christoph Lameter committed
914
915
		goto fail;
	}
Christoph Lameter's avatar
Christoph Lameter committed
916
917
918
919
920
921
922
923

	/* Special debug activities for freeing objects */
	if (!SlabFrozen(page) && !page->freelist)
		remove_full(s, page);
	if (s->flags & SLAB_STORE_USER)
		set_track(s, object, TRACK_FREE, addr);
	trace(s, page, object, 0);
	init_object(s, object, 0);
Christoph Lameter's avatar
Christoph Lameter committed
924
	return 1;
Christoph Lameter's avatar
Christoph Lameter committed
925

Christoph Lameter's avatar
Christoph Lameter committed
926
fail:
927
	slab_fix(s, "Object at 0x%p not freed", object);
Christoph Lameter's avatar
Christoph Lameter committed
928
929
930
	return 0;
}

931
932
static int __init setup_slub_debug(char *str)
{
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
	slub_debug = DEBUG_DEFAULT_FLAGS;
	if (*str++ != '=' || !*str)
		/*
		 * No options specified. Switch on full debugging.
		 */
		goto out;

	if (*str == ',')
		/*
		 * No options but restriction on slabs. This means full
		 * debugging for slabs matching a pattern.
		 */
		goto check_slabs;

	slub_debug = 0;
	if (*str == '-')
		/*
		 * Switch off all debugging measures.
		 */
		goto out;

	/*
	 * Determine which debug features should be switched on
	 */
	for ( ;*str && *str != ','; str++) {
		switch (tolower(*str)) {
		case 'f':
			slub_debug |= SLAB_DEBUG_FREE;
			break;
		case 'z':
			slub_debug |= SLAB_RED_ZONE;
			break;
		case 'p':
			slub_debug |= SLAB_POISON;
			break;
		case 'u':
			slub_debug |= SLAB_STORE_USER;
			break;
		case 't':
			slub_debug |= SLAB_TRACE;
			break;
		default:
			printk(KERN_ERR "slub_debug option '%c' "
				"unknown. skipped\n",*str);
		}
978
979
	}

980
check_slabs:
981
982
	if (*str == ',')
		slub_debug_slabs = str + 1;
983
out:
984
985
986
987
988
	return 1;
}

__setup("slub_debug", setup_slub_debug);

989
990
991
static unsigned long kmem_cache_flags(unsigned long objsize,
	unsigned long flags, const char *name,
	void (*ctor)(void *, struct kmem_cache *, unsigned long))
992
993
994
995
996
997
998
999
1000
1001
{
	/*
	 * The page->offset field is only 16 bit wide. This is an offset
	 * in units of words from the beginning of an object. If the slab
	 * size is bigger then we cannot move the free pointer behind the
	 * object anymore.
	 *
	 * On 32 bit platforms the limit is 256k. On 64bit platforms
	 * the limit is 512k.
	 *
1002
	 * Debugging or ctor may create a need to move the free
1003
1004
	 * pointer. Fail if this happens.
	 */
1005
1006
	if (objsize >= 65535 * sizeof(void *)) {
		BUG_ON(flags & (SLAB_RED_ZONE | SLAB_POISON |
1007
				SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));
1008
1009
		BUG_ON(ctor);
	} else {
1010
1011
1012
1013
		/*
		 * Enable debugging if selected on the kernel commandline.
		 */
		if (slub_debug && (!slub_debug_slabs ||
1014
		    strncmp(slub_debug_slabs, name,
1015
		    	strlen(slub_debug_slabs)) == 0))
1016
1017
1018
1019
				flags |= slub_debug;
	}

	return flags;
1020
1021
}
#else
Christoph Lameter's avatar
Christoph Lameter committed
1022
1023
static inline void setup_object_debug(struct kmem_cache *s,
			struct page *page, void *object) {}
1024

Christoph Lameter's avatar
Christoph Lameter committed
1025
1026
static inline int alloc_debug_processing(struct kmem_cache *s,
	struct page *page, void *object, void *addr) { return 0; }
1027

Christoph Lameter's avatar
Christoph Lameter committed
1028
1029
static inline int free_debug_processing(struct kmem_cache *s,
	struct page *page, void *object, void *addr) { return 0; }
1030
1031
1032
1033
1034

static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
			{ return 1; }
static inline int check_object(struct kmem_cache *s, struct page *page,
			void *object, int active) { return 1; }
Christoph Lameter's avatar
Christoph Lameter committed
1035
static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
1036
1037
1038
1039
1040
1041
static inline unsigned long kmem_cache_flags(unsigned long objsize,
	unsigned long flags, const char *name,
	void (*ctor)(void *, struct kmem_cache *, unsigned long))
{
	return flags;
}
1042
1043
#define slub_debug 0
#endif
Christoph Lameter's avatar
Christoph Lameter committed
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
/*
 * Slab allocation and freeing
 */
static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
{
	struct page * page;
	int pages = 1 << s->order;

	if (s->order)
		flags |= __GFP_COMP;

	if (s->flags & SLAB_CACHE_DMA)
		flags |= SLUB_DMA;

1058
1059
1060
	if (s->flags & SLAB_RECLAIM_ACCOUNT)
		flags |= __GFP_RECLAIMABLE;

Christoph Lameter's avatar
Christoph Lameter committed
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
	if (node == -1)
		page = alloc_pages(flags, s->order);
	else
		page = alloc_pages_node(node, flags, s->order);

	if (!page)
		return NULL;

	mod_zone_page_state(page_zone(page),
		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
		pages);

	return page;
}

static void setup_object(struct kmem_cache *s, struct page *page,
				void *object)
{
Christoph Lameter's avatar
Christoph Lameter committed
1080
	setup_object_debug(s, page, object);
1081
	if (unlikely(s->ctor))
1082
		s->ctor(object, s, 0);
Christoph Lameter's avatar
Christoph Lameter committed
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
}

static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
	struct page *page;
	struct kmem_cache_node *n;
	void *start;
	void *end;
	void *last;
	void *p;

Christoph Lameter's avatar
Christoph Lameter committed
1094
	BUG_ON(flags & GFP_SLAB_BUG_MASK);
Christoph Lameter's avatar
Christoph Lameter committed
1095
1096
1097
1098

	if (flags & __GFP_WAIT)
		local_irq_enable();

Christoph Lameter's avatar
Christoph Lameter committed
1099
1100
	page = allocate_slab(s,
		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
Christoph Lameter's avatar
Christoph Lameter committed
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
	if (!page)
		goto out;

	n = get_node(s, page_to_nid(page));
	if (n)
		atomic_long_inc(&n->nr_slabs);
	page->offset = s->offset / sizeof(void *);
	page->slab = s;
	page->flags |= 1 << PG_slab;
	if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
			SLAB_STORE_USER | SLAB_TRACE))
1112
		SetSlabDebug(page);
Christoph Lameter's avatar
Christoph Lameter committed
1113
1114
1115
1116
1117
1118
1119
1120

	start = page_address(page);
	end = start + s->objects * s->size;

	if (unlikely(s->flags & SLAB_POISON))
		memset(start, POISON_INUSE, PAGE_SIZE << s->order);

	last = start;
1121
	for_each_object(p, s, start) {
Christoph Lameter's avatar
Christoph Lameter committed
1122
1123
1124
1125
1126
1127
1128
1129
		setup_object(s, page, last);
		set_freepointer(s, last, p);
		last = p;
	}
	setup_object(s, page, last);
	set_freepointer(s, last, NULL);

	page->freelist = start;
1130
	page->lockless_freelist = NULL;
Christoph Lameter's avatar
Christoph Lameter committed
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
	page->inuse = 0;
out:
	if (flags & __GFP_WAIT)
		local_irq_disable();
	return page;
}

static void __free_slab(struct kmem_cache *s, struct page *page)
{
	int pages = 1 << s->order;

1142
	if (unlikely(SlabDebug(page))) {
Christoph Lameter's avatar
Christoph Lameter committed
1143
1144
1145
		void *p;

		slab_pad_check(s, page);
1146
		for_each_object(p, s, page_address(page))
Christoph Lameter's avatar
Christoph Lameter committed
1147
			check_object(s, page, p, 0);
1148
		ClearSlabDebug(page);
Christoph Lameter's avatar
Christoph Lameter committed
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
	}

	mod_zone_page_state(page_zone(page),
		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
		- pages);

	page->mapping = NULL;
	__free_pages(page, s->order);
}

static void rcu_free_slab(struct rcu_head *h)
{
	struct page *page;

	page = container_of((struct list_head *)h, struct page, lru);
	__free_slab(page->slab, page);
}

static void free_slab(struct kmem_cache *s, struct page *page)
{
	if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
		/*
		 * RCU free overloads the RCU head over the LRU
		 */
		struct rcu_head *head = (void *)&page->lru;

		call_rcu(head, rcu_free_slab);
	} else
		__free_slab(s, page);
}

static void discard_slab(struct kmem_cache *s, struct page *page)
{
	struct kmem_cache_node *n = get_node(s, page_to_nid(page));

	atomic_long_dec(&n->nr_slabs);
	reset_page_mapcount(page);
1187
	__ClearPageSlab(page);
Christoph Lameter's avatar
Christoph Lameter committed
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
	free_slab(s, page);
}

/*
 * Per slab locking using the pagelock
 */
static __always_inline void slab_lock(struct page *page)
{
	bit_spin_lock(PG_locked, &page->flags);
}

static __always_inline void slab_unlock(struct page *page)
{
	bit_spin_unlock(PG_locked, &page->flags);
}

static __always_inline int slab_trylock(struct page *page)
{
	int rc = 1;

	rc = bit_spin_trylock(PG_locked, &page->flags);
	return rc;
}

/*
 * Management of partially allocated slabs
 */
Christoph Lameter's avatar
Christoph Lameter committed
1215
static void add_partial_tail(struct kmem_cache_node *n, struct page *page)
Christoph Lameter's avatar
Christoph Lameter committed
1216
{
Christoph Lameter's avatar
Christoph Lameter committed
1217
1218
1219
1220
1221
	spin_lock(&n->list_lock);
	n->nr_partial++;
	list_add_tail(&page->lru, &n->partial);
	spin_unlock(&n->list_lock);
}
Christoph Lameter's avatar
Christoph Lameter committed
1222

Christoph Lameter's avatar
Christoph Lameter committed
1223
1224
static void add_partial(struct kmem_cache_node *n, struct page *page)
{
Christoph Lameter's avatar
Christoph Lameter committed
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
	spin_lock(&n->list_lock);
	n->nr_partial++;
	list_add(&page->lru, &n->partial);
	spin_unlock(&n->list_lock);
}

static void remove_partial(struct kmem_cache *s,
						struct page *page)
{
	struct kmem_cache_node *n = get_node(s, page_to_nid(page));

	spin_lock(&n->list_lock);
	list_del(&page->lru);
	n->nr_partial--;
	spin_unlock(&n->list_lock);
}

/*
Christoph Lameter's avatar
Christoph Lameter committed
1243
 * Lock slab and remove from the partial list.
Christoph Lameter's avatar
Christoph Lameter committed
1244
 *
Christoph Lameter's avatar
Christoph Lameter committed
1245
 * Must hold list_lock.
Christoph Lameter's avatar
Christoph Lameter committed
1246
 */
1247
static inline int lock_and_freeze_slab(struct kmem_cache_node *n, struct page *page)
Christoph Lameter's avatar
Christoph Lameter committed
1248
1249
1250
1251
{
	if (slab_trylock(page)) {
		list_del(&page->lru);
		n->nr_partial--;
1252
		SetSlabFrozen(page);
Christoph Lameter's avatar
Christoph Lameter committed
1253
1254
1255
1256
1257
1258
		return 1;
	}
	return 0;
}

/*
Christoph Lameter's avatar
Christoph Lameter committed
1259
 * Try to allocate a partial slab from a specific node.
Christoph Lameter's avatar
Christoph Lameter committed
1260
1261
1262
1263
1264
1265
1266
1267
 */
static struct page *get_partial_node(struct kmem_cache_node *n)
{
	struct page *page;

	/*
	 * Racy check. If we mistakenly see no partial slabs then we
	 * just allocate an empty slab. If we mistakenly try to get a
Christoph Lameter's avatar
Christoph Lameter committed
1268
1269
	 * partial slab and there is none available then get_partials()
	 * will return NULL.
Christoph Lameter's avatar
Christoph Lameter committed
1270
1271
1272
1273
1274
1275
	 */
	if (!n || !n->nr_partial)
		return NULL;

	spin_lock(&n->list_lock);
	list_for_each_entry(page, &n->partial, lru)
1276
		if (lock_and_freeze_slab(n, page))
Christoph Lameter's avatar
Christoph Lameter committed
1277
1278
1279
1280
1281
1282
1283
1284
			goto out;
	page = NULL;
out:
	spin_unlock(&n->list_lock);
	return page;
}

/*
Christoph Lameter's avatar
Christoph Lameter committed
1285
 * Get a page from somewhere. Search in increasing NUMA distances.
Christoph Lameter's avatar
Christoph Lameter committed
1286
1287
1288
1289
1290
1291
1292
1293
1294
 */
static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
{
#ifdef CONFIG_NUMA
	struct zonelist *zonelist;
	struct zone **z;
	struct page *page;

	/*
Christoph Lameter's avatar
Christoph Lameter committed
1295
1296
1297
1298
	 * The defrag ratio allows a configuration of the tradeoffs between
	 * inter node defragmentation and node local allocations. A lower
	 * defrag_ratio increases the tendency to do local allocations
	 * instead of attempting to obtain partial slabs from other nodes.
Christoph Lameter's avatar
Christoph Lameter committed
1299
	 *
Christoph Lameter's avatar
Christoph Lameter committed
1300
1301
1302
1303
	 * If the defrag_ratio is set to 0 then kmalloc() always
	 * returns node local objects. If the ratio is higher then kmalloc()
	 * may return off node objects because partial slabs are obtained
	 * from other nodes and filled up.
Christoph Lameter's avatar
Christoph Lameter committed
1304
1305
	 *
	 * If /sys/slab/xx/defrag_ratio is set to 100 (which makes
Christoph Lameter's avatar
Christoph Lameter committed
1306
1307
1308
1309
1310
	 * defrag_ratio = 1000) then every (well almost) allocation will
	 * first attempt to defrag slab caches on other nodes. This means
	 * scanning over all nodes to look for partial slabs which may be
	 * expensive if we do it every time we are trying to find a slab
	 * with available objects.
Christoph Lameter's avatar
Christoph Lameter committed
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
	 */
	if (!s->defrag_ratio || get_cycles() % 1024 > s->defrag_ratio)
		return NULL;

	zonelist = &NODE_DATA(slab_node(current->mempolicy))
					->node_zonelists[gfp_zone(flags)];
	for (z = zonelist->zones; *z; z++) {
		struct kmem_cache_node *n;

		n = get_node(s, zone_to_nid(*z));

		if (n && cpuset_zone_allowed_hardwall(*z, flags) &&
Christoph Lameter's avatar
Christoph Lameter committed
1323
				n->nr_partial > MIN_PARTIAL) {
Christoph Lameter's avatar
Christoph Lameter committed
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
			page = get_partial_node(n);
			if (page)
				return page;
		}
	}
#endif
	return NULL;
}

/*
 * Get a partial page, lock it and return it.
 */
static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
{
	struct page *page;
	int searchnode = (node == -1) ? numa_node_id() : node;

	page = get_partial_node(get_node(s, searchnode));
	if (page || (flags & __GFP_THISNODE))
		return page;

	return get_any_partial(s, flags);
}

/*
 * Move a page back to the lists.
 *
 * Must be called with the slab lock held.
 *
 * On exit the slab lock will have been dropped.
 */
1355
static void unfreeze_slab(struct kmem_cache *s, struct page *page)
Christoph Lameter's avatar
Christoph Lameter committed
1356
{
Christoph Lameter's avatar
Christoph Lameter committed
1357
1358
	struct kmem_cache_node *n = get_node(s, page_to_nid(page));

1359
	ClearSlabFrozen(page);
Christoph Lameter's avatar
Christoph Lameter committed
1360
	if (page->inuse) {
Christoph Lameter's avatar
Christoph Lameter committed
1361

Christoph Lameter's avatar
Christoph Lameter committed
1362
		if (page->freelist)
Christoph Lameter's avatar
Christoph Lameter committed
1363
			add_partial(n, page);
1364
		else if (SlabDebug(page) && (s->flags & SLAB_STORE_USER))
Christoph Lameter's avatar
Christoph Lameter committed
1365
			add_full(n, page);
Christoph Lameter's avatar
Christoph Lameter committed
1366
		slab_unlock(page);
Christoph Lameter's avatar
Christoph Lameter committed
1367

Christoph Lameter's avatar
Christoph Lameter committed
1368
	} else {
Christoph Lameter's avatar
Christoph Lameter committed
1369
1370
		if (n->nr_partial < MIN_PARTIAL) {
			/*
Christoph Lameter's avatar
Christoph Lameter committed
1371
1372
1373
1374
1375
1376
			 * Adding an empty slab to the partial slabs in order
			 * to avoid page allocator overhead. This slab needs
			 * to come after the other slabs with objects in
			 * order to fill them up. That way the size of the
			 * partial list stays small. kmem_cache_shrink can
			 * reclaim empty slabs from the partial list.
Christoph Lameter's avatar
Christoph Lameter committed
1377
1378
1379
1380
1381
1382
1383
			 */
			add_partial_tail(n, page);
			slab_unlock(page);
		} else {
			slab_unlock(page);
			discard_slab(s, page);
		}
Christoph Lameter's avatar
Christoph Lameter committed
1384
1385
1386
1387
1388
1389
1390
1391
	}
}

/*
 * Remove the cpu slab
 */
static void deactivate_slab(struct kmem_cache *s, struct page *page, int cpu)
{
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
	/*
	 * Merge cpu freelist into freelist. Typically we get here
	 * because both freelists are empty. So this is unlikely
	 * to occur.
	 */
	while (unlikely(page->lockless_freelist)) {
		void **object;

		/* Retrieve object from cpu_freelist */
		object = page->lockless_freelist;
		page->lockless_freelist = page->lockless_freelist[page->offset];

		/* And put onto the regular freelist */
		object[page->offset] = page->freelist;
		page->freelist = object;
		page->inuse--;
	}
Christoph Lameter's avatar
Christoph Lameter committed
1409
	s->cpu_slab[cpu] = NULL;
1410
	unfreeze_slab(s, page);
Christoph Lameter's avatar
Christoph Lameter committed
1411
1412
}

1413
static inline void flush_slab(struct kmem_cache *s, struct page *page, int cpu)
Christoph Lameter's avatar
Christoph Lameter committed
1414
1415
1416
1417
1418
1419
1420
1421
1422
{
	slab_lock(page);
	deactivate_slab(s, page, cpu);
}

/*
 * Flush cpu slab.
 * Called from IPI handler with interrupts disabled.
 */
1423
static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
Christoph Lameter's avatar
Christoph Lameter committed
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
{
	struct page *page = s->cpu_slab[cpu];

	if (likely(page))
		flush_slab(s, page, cpu);
}

static void flush_cpu_slab(void *d)
{
	struct kmem_cache *s = d;
	int cpu = smp_processor_id();

	__flush_cpu_slab(s, cpu);
}

static void flush_all(struct kmem_cache *s)
{
#ifdef CONFIG_SMP
	on_each_cpu(flush_cpu_slab, s, 1, 1);
#else
	unsigned long flags;

	local_irq_save(flags);
	flush_cpu_slab(s);
	local_irq_restore(flags);
#endif
}

/*
1453
1454
1455
1456
 * Slow path. The lockless freelist is empty or we need to perform
 * debugging duties.
 *
 * Interrupts are disabled.
Christoph Lameter's avatar
Christoph Lameter committed
1457
 *
1458
1459
1460
 * Processing is still very fast if new objects have been freed to the
 * regular freelist. In that case we simply take over the regular freelist
 * as the lockless freelist and zap the regular freelist.
Christoph Lameter's avatar
Christoph Lameter committed
1461
 *
1462
1463
1464
 * If that is not working then we fall back to the partial lists. We take the
 * first element of the freelist as the object to allocate now and move the
 * rest of the freelist to the lockless freelist.
Christoph Lameter's avatar
Christoph Lameter committed
1465
 *
1466
1467
 * And if we were unable to get a new slab from the partial slab lists then
 * we need to allocate a new slab. This is slowest path since we may sleep.
Christoph Lameter's avatar
Christoph Lameter committed
1468
 */
1469
1470
static void *__slab_alloc(struct kmem_cache *s,
		gfp_t gfpflags, int node, void *addr, struct page *page)
Christoph Lameter's avatar
Christoph Lameter committed
1471
1472
{
	void **object;
1473
	int cpu = smp_processor_id();
Christoph Lameter's avatar
Christoph Lameter committed
1474
1475
1476
1477
1478
1479
1480

	if (!page)
		goto new_slab;

	slab_lock(page);
	if (unlikely(node != -1 && page_to_nid(page) != node))
		goto another_slab;
1481
load_freelist:
Christoph Lameter's avatar
Christoph Lameter committed
1482
1483
1484
	object = page->freelist;
	if (unlikely(!object))
		goto another_slab;
1485
	if (unlikely(SlabDebug(page)))
Christoph Lameter's avatar
Christoph Lameter committed
1486
1487
		goto debug;

1488
1489
1490
1491
	object = page->freelist;
	page->lockless_freelist = object[page->offset];
	page->inuse = s->objects;
	page->freelist = NULL;
Christoph Lameter's avatar
Christoph Lameter committed
1492
1493
1494
1495
1496
1497
1498
1499
	slab_unlock(page);
	return object;

another_slab:
	deactivate_slab(s, page, cpu);

new_slab:
	page = get_partial(s, gfpflags, node);
1500
	if (page) {
Christoph Lameter's avatar
Christoph Lameter committed
1501
		s->cpu_slab[cpu] = page;
1502
		goto load_freelist;
Christoph Lameter's avatar
Christoph Lameter committed
1503
1504
1505
1506
1507
1508
1509
	}

	page = new_slab(s, gfpflags, node);
	if (page) {
		cpu = smp_processor_id();
		if (s->cpu_slab[cpu]) {
			/*
Christoph Lameter's avatar
Christoph Lameter committed
1510
1511
1512
1513
1514
			 * Someone else populated the cpu_slab while we
			 * enabled interrupts, or we have gotten scheduled
			 * on another cpu. The page may not be on the
			 * requested node even if __GFP_THISNODE was
			 * specified. So we need to recheck.
Christoph Lameter's avatar
Christoph Lameter committed
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
			 */
			if (node == -1 ||
				page_to_nid(s->cpu_slab[cpu]) == node) {
				/*
				 * Current cpuslab is acceptable and we
				 * want the current one since its cache hot
				 */
				discard_slab(s, page);
				page = s->cpu_slab[cpu];
				slab_lock(page);
1525
				goto load_freelist;
Christoph Lameter's avatar
Christoph Lameter committed
1526
			}
Christoph Lameter's avatar
Christoph Lameter committed
1527
			/* New slab does not fit our expectations */
Christoph Lameter's avatar
Christoph Lameter committed
1528
1529
1530
			flush_slab(s, s->cpu_slab[cpu], cpu);
		}
		slab_lock(page);
1531
1532
1533
		SetSlabFrozen(page);
		s->cpu_slab[cpu] = page;
		goto load_freelist;
Christoph Lameter's avatar
Christoph Lameter committed
1534
1535
1536
	}
	return NULL;
debug:
1537
	object = page->freelist;
Christoph Lameter's avatar
Christoph Lameter committed
1538
	if (!alloc_debug_processing(s, page, object, addr))
Christoph Lameter's avatar
Christoph Lameter committed
1539
		goto another_slab;
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557

	page->inuse++;
	page->freelist = object[page->offset];
	slab_unlock(page);
	return object;
}

/*
 * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
 * have the fastpath folded into their functions. So no function call
 * overhead for requests that can be satisfied on the fastpath.
 *
 * The fastpath works by first checking if the lockless freelist can be used.
 * If not then __slab_alloc is called for slow processing.
 *
 * Otherwise we can simply pick the next object from the lockless free list.
 */
static void __always_inline *slab_alloc(struct kmem_cache *s,
1558
		gfp_t gfpflags, int node, void *addr)
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
{
	struct page *page;
	void **object;
	unsigned long flags;

	local_irq_save(flags);
	page = s->cpu_slab[smp_processor_id()];
	if (unlikely(!page || !page->lockless_freelist ||
			(node != -1 && page_to_nid(page) != node)))

		object = __slab_alloc(s, gfpflags, node, addr, page);

	else {
		object = page->lockless_freelist;
		page->lockless_freelist = object[page->offset];
	}
	local_irq_restore(flags);
1576
1577

	if (unlikely((gfpflags & __GFP_ZERO) && object))
1578
		memset(object, 0, s->objsize);
1579

1580
	return object;
Christoph Lameter's avatar
Christoph Lameter committed
1581
1582
1583
1584
}

void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
1585
	return slab_alloc(s, gfpflags, -1, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
1586
1587
1588
1589
1590
1591
}
EXPORT_SYMBOL(kmem_cache_alloc);

#ifdef CONFIG_NUMA
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
1592
	return slab_alloc(s, gfpflags, node, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
1593
1594
1595
1596
1597
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
#endif

/*
1598
1599
 * Slow patch handling. This may still be called frequently since objects
 * have a longer lifetime than the cpu slabs in most processing loads.
Christoph Lameter's avatar
Christoph Lameter committed
1600
 *
Christoph Lameter's avatar