slub.c 80.3 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
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
/*
 * 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.
 *
 * Slabs with free elements are kept on a partial list.
 * There is no list for full slabs. If an object in a full slab is
 * freed then the slab will show up again on the partial lists.
 * Otherwise there is no need to track full slabs unless we have to
 * track full slabs for debugging purposes.
 *
 * 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.
 *
 * PageActive 		The slab is used as a cpu cache. Allocations
 * 			may be performed from the slab. The slab is not
 * 			on any slab list and cannot be moved onto one.
 *
 * PageError		Slab requires special handling due to debug
 * 			options set. This moves	slab handling out of
 * 			the fast path.
 */

/*
 * 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
 *   enough frequent updates. There are 16 pointers in a cacheline.so at
 *   max 16 cpus could compete. Likely okay.
 *
 * - 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

125
126
127
128
/*
 * 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
129
130
#define MIN_PARTIAL 2

131
132
133
134
135
136
137
/*
 * 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
138
139
140
141
142
143
144
145
146
147
148
149
#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
				SLAB_POISON | SLAB_STORE_USER)
/*
 * 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
150
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
Christoph Lameter's avatar
Christoph Lameter committed
151
152
153
#endif

#ifndef ARCH_SLAB_MINALIGN
154
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
Christoph Lameter's avatar
Christoph Lameter committed
155
156
157
158
159
#endif

/* Internal SLUB flags */
#define __OBJECT_POISON 0x80000000	/* Poison object */

160
161
162
163
164
/* 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
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
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
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
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
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 */
	UP,		/* Everything works */
	SYSFS		/* Sysfs up */
} slab_state = DOWN;

/* A list of all slab caches on the system */
static DECLARE_RWSEM(slub_lock);
LIST_HEAD(slab_caches);

#ifdef CONFIG_SYSFS
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
static int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; }
static void sysfs_slab_remove(struct kmem_cache *s) {}
#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
}

/*
 * 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) {
			printk(KERN_ERR "%10s 0x%p: ", text, addr + i);
			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);
	}
}

/*
 * Slow version of get and set free pointer.
 *
 * This requires touching the cache lines of kmem_cache.
 * The offset can also be obtained from the page. In that
 * case it is in the cacheline that we already need to touch.
 */
static void *get_freepointer(struct kmem_cache *s, void *object)
{
	return *(void **)(object + s->offset);
}

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

/*
 * 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 };

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)
{
	if (s->flags & SLAB_STORE_USER) {
		set_track(s, object, TRACK_FREE, NULL);
		set_track(s, object, TRACK_ALLOC, NULL);
	}
}

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

	printk(KERN_ERR "%s: ", s);
	__print_symbol("%s", (unsigned long)t->addr);
	printk(" jiffies_ago=%lu cpu=%u pid=%d\n", jiffies - t->when, t->cpu, t->pid);
}

static void print_trailer(struct kmem_cache *s, u8 *p)
{
	unsigned int off;	/* Offset of last byte */

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

	printk(KERN_ERR "FreePointer 0x%p -> 0x%p\n",
			p + s->offset,
			get_freepointer(s, p));

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

	if (s->flags & SLAB_STORE_USER) {
		print_track("Last alloc", get_track(s, p, TRACK_ALLOC));
		print_track("Last free ", get_track(s, p, TRACK_FREE));
		off += 2 * sizeof(struct track);
	}

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

static void object_err(struct kmem_cache *s, struct page *page,
			u8 *object, char *reason)
{
	u8 *addr = page_address(page);

	printk(KERN_ERR "*** SLUB %s: %s@0x%p slab 0x%p\n",
			s->name, reason, object, page);
	printk(KERN_ERR "    offset=%tu flags=0x%04lx inuse=%u freelist=0x%p\n",
		object - addr, page->flags, page->inuse, page->freelist);
	if (object > addr + 16)
		print_section("Bytes b4", object - 16, 16);
	print_section("Object", object, min(s->objsize, 128));
	print_trailer(s, object);
	dump_stack();
}

static void slab_err(struct kmem_cache *s, struct page *page, char *reason, ...)
{
	va_list args;
	char buf[100];

	va_start(args, reason);
	vsnprintf(buf, sizeof(buf), reason, args);
	va_end(args);
	printk(KERN_ERR "*** SLUB %s: %s in slab @0x%p\n", s->name, buf,
		page);
	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);
}

static int check_bytes(u8 *start, unsigned int value, unsigned int bytes)
{
	while (bytes) {
		if (*start != (u8)value)
			return 0;
		start++;
		bytes--;
	}
	return 1;
}

408
409
static inline int check_valid_pointer(struct kmem_cache *s,
				struct page *page, const void *object)
Christoph Lameter's avatar
Christoph Lameter committed
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
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
457
{
	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;
}

/*
 * 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.
 * 	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.
 * 	Padding is extended to word size if Redzoning is enabled
 * 	and objsize == inuse.
 * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
 * 	0xcc (RED_ACTIVE) for objects in use.
 *
 * object + s->inuse
 * 	A. Free pointer (if we cannot overwrite object on free)
 * 	B. Tracking data for SLAB_STORE_USER
 * 	C. Padding to reach required alignment boundary
 * 		Padding is done using 0x5a (POISON_INUSE)
 *
 * object + s->size
 *
 * If slabcaches are merged then the objsize and inuse boundaries are to
 * be ignored. And therefore no slab options that rely on these boundaries
 * may be used with merged slabcaches.
 */

static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
						void *from, void *to)
{
458
	printk(KERN_ERR "@@@ SLUB %s: Restoring %s (0x%x) from 0x%p-0x%p\n",
Christoph Lameter's avatar
Christoph Lameter committed
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
		s->name, message, data, from, to - 1);
	memset(from, data, to - from);
}

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;

	if (check_bytes(p + off, POISON_INUSE, s->size - off))
		return 1;

	object_err(s, page, p, "Object padding check fails");

	/*
	 * Restore padding
	 */
	restore_bytes(s, "object padding", POISON_INUSE, p + off, p + s->size);
	return 0;
}

static int slab_pad_check(struct kmem_cache *s, struct page *page)
{
	u8 *p;
	int length, remainder;

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

	p = page_address(page);
	length = s->objects * s->size;
	remainder = (PAGE_SIZE << s->order) - length;
	if (!remainder)
		return 1;

	if (!check_bytes(p + length, POISON_INUSE, remainder)) {
505
		slab_err(s, page, "Padding check failed");
Christoph Lameter's avatar
Christoph Lameter committed
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
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
581
582
583
584
585
586
587
588
589
590
		restore_bytes(s, "slab padding", POISON_INUSE, p + length,
			p + length + remainder);
		return 0;
	}
	return 1;
}

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;

		if (!check_bytes(endobject, red, s->inuse - s->objsize)) {
			object_err(s, page, object,
			active ? "Redzone Active" : "Redzone Inactive");
			restore_bytes(s, "redzone", red,
				endobject, object + s->inuse);
			return 0;
		}
	} else {
		if ((s->flags & SLAB_POISON) && s->objsize < s->inuse &&
			!check_bytes(endobject, POISON_INUSE,
					s->inuse - s->objsize)) {
		object_err(s, page, p, "Alignment padding check fails");
		/*
		 * Fix it so that there will not be another report.
		 *
		 * Hmmm... We may be corrupting an object that now expects
		 * to be longer than allowed.
		 */
		restore_bytes(s, "alignment padding", POISON_INUSE,
			endobject, object + s->inuse);
		}
	}

	if (s->flags & SLAB_POISON) {
		if (!active && (s->flags & __OBJECT_POISON) &&
			(!check_bytes(p, POISON_FREE, s->objsize - 1) ||
				p[s->objsize - 1] != POISON_END)) {

			object_err(s, page, p, "Poison check failed");
			restore_bytes(s, "Poison", POISON_FREE,
						p, p + s->objsize -1);
			restore_bytes(s, "Poison", POISON_END,
					p + s->objsize - 1, p + s->objsize);
			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
		 * another error because the object count maybe
		 * wrong now.
		 */
		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)) {
591
592
		slab_err(s, page, "Not a valid slab page flags=%lx "
			"mapping=0x%p count=%d", page->flags, page->mapping,
Christoph Lameter's avatar
Christoph Lameter committed
593
594
595
596
			page_count(page));
		return 0;
	}
	if (page->offset * sizeof(void *) != s->offset) {
597
598
		slab_err(s, page, "Corrupted offset %lu flags=0x%lx "
			"mapping=0x%p count=%d",
Christoph Lameter's avatar
Christoph Lameter committed
599
600
601
602
603
604
605
			(unsigned long)(page->offset * sizeof(void *)),
			page->flags,
			page->mapping,
			page_count(page));
		return 0;
	}
	if (page->inuse > s->objects) {
606
607
608
		slab_err(s, page, "inuse %u > max %u @0x%p flags=%lx "
			"mapping=0x%p count=%d",
			s->name, page->inuse, s->objects, page->flags,
Christoph Lameter's avatar
Christoph Lameter committed
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
			page->mapping, page_count(page));
		return 0;
	}
	/* Slab_pad_check fixes things up after itself */
	slab_pad_check(s, page);
	return 1;
}

/*
 * Determine if a certain object on a page is on the freelist and
 * therefore free. Must hold the slab lock for cpu slabs to
 * guarantee that the chains are consistent.
 */
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 {
638
639
				slab_err(s, page, "Freepointer 0x%p corrupt",
									fp);
Christoph Lameter's avatar
Christoph Lameter committed
640
641
				page->freelist = NULL;
				page->inuse = s->objects;
642
643
644
				printk(KERN_ERR "@@@ SLUB %s: Freelist "
					"cleared. Slab 0x%p\n",
					s->name, page);
Christoph Lameter's avatar
Christoph Lameter committed
645
646
647
648
649
650
651
652
653
654
				return 0;
			}
			break;
		}
		object = fp;
		fp = get_freepointer(s, object);
		nr++;
	}

	if (page->inuse != s->objects - nr) {
655
656
657
		slab_err(s, page, "Wrong object count. Counter is %d but "
			"counted were %d", s, page, page->inuse,
							s->objects - nr);
Christoph Lameter's avatar
Christoph Lameter committed
658
		page->inuse = s->objects - nr;
659
660
		printk(KERN_ERR "@@@ SLUB %s: Object count adjusted. "
			"Slab @0x%p\n", s->name, page);
Christoph Lameter's avatar
Christoph Lameter committed
661
662
663
664
	}
	return search == NULL;
}

665
666
667
/*
 * Tracking of fully allocated slabs for debugging
 */
Christoph Lameter's avatar
Christoph Lameter committed
668
static void add_full(struct kmem_cache_node *n, struct page *page)
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
{
	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
689
690
691
692
693
694
695
static int alloc_object_checks(struct kmem_cache *s, struct page *page,
							void *object)
{
	if (!check_slab(s, page))
		goto bad;

	if (object && !on_freelist(s, page, object)) {
696
697
		slab_err(s, page, "Object 0x%p already allocated", object);
		goto bad;
Christoph Lameter's avatar
Christoph Lameter committed
698
699
700
701
	}

	if (!check_valid_pointer(s, page, object)) {
		object_err(s, page, object, "Freelist Pointer check fails");
702
		goto bad;
Christoph Lameter's avatar
Christoph Lameter committed
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
	}

	if (!object)
		return 1;

	if (!check_object(s, page, object, 0))
		goto bad;

	return 1;
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
		 * as used avoids touching the remainder.
		 */
		printk(KERN_ERR "@@@ SLUB: %s slab 0x%p. Marking all objects used.\n",
			s->name, page);
		page->inuse = s->objects;
		page->freelist = NULL;
		/* Fix up fields that may be corrupted */
		page->offset = s->offset / sizeof(void *);
	}
	return 0;
}

static int free_object_checks(struct kmem_cache *s, struct page *page,
							void *object)
{
	if (!check_slab(s, page))
		goto fail;

	if (!check_valid_pointer(s, page, object)) {
736
		slab_err(s, page, "Invalid object pointer 0x%p", object);
Christoph Lameter's avatar
Christoph Lameter committed
737
738
739
740
		goto fail;
	}

	if (on_freelist(s, page, object)) {
741
		slab_err(s, page, "Object 0x%p already free", object);
Christoph Lameter's avatar
Christoph Lameter committed
742
743
744
745
746
747
748
749
		goto fail;
	}

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

	if (unlikely(s != page->slab)) {
		if (!PageSlab(page))
750
751
			slab_err(s, page, "Attempt to free object(0x%p) "
				"outside of slab", object);
Christoph Lameter's avatar
Christoph Lameter committed
752
		else
753
		if (!page->slab) {
Christoph Lameter's avatar
Christoph Lameter committed
754
			printk(KERN_ERR
755
				"SLUB <none>: no slab for object 0x%p.\n",
Christoph Lameter's avatar
Christoph Lameter committed
756
						object);
757
758
			dump_stack();
		}
Christoph Lameter's avatar
Christoph Lameter committed
759
		else
760
761
			slab_err(s, page, "object at 0x%p belongs "
				"to slab %s", object, page->slab->name);
Christoph Lameter's avatar
Christoph Lameter committed
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
		goto fail;
	}
	return 1;
fail:
	printk(KERN_ERR "@@@ SLUB: %s slab 0x%p object at 0x%p not freed.\n",
		s->name, page, object);
	return 0;
}

/*
 * 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;

	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)
{
	if (PageError(page)) {
		init_object(s, object, 0);
		init_tracking(s, object);
	}

809
810
	if (unlikely(s->ctor))
		s->ctor(object, s, SLAB_CTOR_CONSTRUCTOR);
Christoph Lameter's avatar
Christoph Lameter committed
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
}

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;

	BUG_ON(flags & ~(GFP_DMA | GFP_LEVEL_MASK));

	if (flags & __GFP_WAIT)
		local_irq_enable();

	page = allocate_slab(s, flags & GFP_LEVEL_MASK, node);
	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))
		page->flags |= 1 << PG_error;

	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;
	for (p = start + s->size; p < end; p += s->size) {
		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;
	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;

	if (unlikely(PageError(page) || s->dtor)) {
		void *start = page_address(page);
		void *end = start + (pages << PAGE_SHIFT);
		void *p;

		slab_pad_check(s, page);
		for (p = start; p <= end - s->size; p += s->size) {
			if (s->dtor)
				s->dtor(p, s, 0);
			check_object(s, page, p, 0);
		}
	}

	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);
	page->flags &= ~(1 << PG_slab | 1 << PG_error);
	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
945
static void add_partial_tail(struct kmem_cache_node *n, struct page *page)
Christoph Lameter's avatar
Christoph Lameter committed
946
{
Christoph Lameter's avatar
Christoph Lameter committed
947
948
949
950
951
	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
952

Christoph Lameter's avatar
Christoph Lameter committed
953
954
static void add_partial(struct kmem_cache_node *n, struct page *page)
{
Christoph Lameter's avatar
Christoph Lameter committed
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
	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);
}

/*
 * Lock page and remove it from the partial list
 *
 * Must hold list_lock
 */
static int lock_and_del_slab(struct kmem_cache_node *n, struct page *page)
{
	if (slab_trylock(page)) {
		list_del(&page->lru);
		n->nr_partial--;
		return 1;
	}
	return 0;
}

/*
 * Try to get a partial slab from a specific node
 */
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
	 * partial slab then get_partials() will return NULL.
	 */
	if (!n || !n->nr_partial)
		return NULL;

	spin_lock(&n->list_lock);
	list_for_each_entry(page, &n->partial, lru)
		if (lock_and_del_slab(n, page))
			goto out;
	page = NULL;
out:
	spin_unlock(&n->list_lock);
	return page;
}

/*
 * Get a page from somewhere. Search in increasing NUMA
 * distances.
 */
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;

	/*
	 * The defrag ratio allows to configure the tradeoffs between
	 * inter node defragmentation and node local allocations.
	 * A lower defrag_ratio increases the tendency to do local
	 * allocations instead of scanning throught the partial
	 * lists on other nodes.
	 *
	 * If defrag_ratio is set to 0 then kmalloc() always
	 * returns node local objects. If its higher then kmalloc()
	 * may return off node objects in order to avoid fragmentation.
	 *
	 * A higher ratio means slabs may be taken from other nodes
	 * thus reducing the number of partial slabs on those nodes.
	 *
	 * If /sys/slab/xx/defrag_ratio is set to 100 (which makes
	 * 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 a bit expensive to do on every slab allocation.
	 */
	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
1054
				n->nr_partial > MIN_PARTIAL) {
Christoph Lameter's avatar
Christoph Lameter committed
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
			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.
 */
static void putback_slab(struct kmem_cache *s, struct page *page)
{
Christoph Lameter's avatar
Christoph Lameter committed
1088
1089
	struct kmem_cache_node *n = get_node(s, page_to_nid(page));

Christoph Lameter's avatar
Christoph Lameter committed
1090
	if (page->inuse) {
Christoph Lameter's avatar
Christoph Lameter committed
1091

Christoph Lameter's avatar
Christoph Lameter committed
1092
		if (page->freelist)
Christoph Lameter's avatar
Christoph Lameter committed
1093
1094
1095
			add_partial(n, page);
		else if (PageError(page) && (s->flags & SLAB_STORE_USER))
			add_full(n, page);
Christoph Lameter's avatar
Christoph Lameter committed
1096
		slab_unlock(page);
Christoph Lameter's avatar
Christoph Lameter committed
1097

Christoph Lameter's avatar
Christoph Lameter committed
1098
	} else {
Christoph Lameter's avatar
Christoph Lameter committed
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
		if (n->nr_partial < MIN_PARTIAL) {
			/*
			 * Adding an empty page to the partial slabs in order
			 * to avoid page allocator overhead. This page needs to
			 * come after all the others that are not fully empty
			 * in order to make sure that we do maximum
			 * defragmentation.
			 */
			add_partial_tail(n, page);
			slab_unlock(page);
		} else {
			slab_unlock(page);
			discard_slab(s, page);
		}
Christoph Lameter's avatar
Christoph Lameter committed
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
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
	}
}

/*
 * Remove the cpu slab
 */
static void deactivate_slab(struct kmem_cache *s, struct page *page, int cpu)
{
	s->cpu_slab[cpu] = NULL;
	ClearPageActive(page);

	putback_slab(s, page);
}

static void flush_slab(struct kmem_cache *s, struct page *page, int cpu)
{
	slab_lock(page);
	deactivate_slab(s, page, cpu);
}

/*
 * Flush cpu slab.
 * Called from IPI handler with interrupts disabled.
 */
static void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
	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
}

/*
 * slab_alloc is optimized to only modify two cachelines on the fast path
 * (aside from the stack):
 *
 * 1. The page struct
 * 2. The first cacheline of the object to be allocated.
 *
 * The only cache lines that are read (apart from code) is the
 * per cpu array in the kmem_cache struct.
 *
 * Fastpath is not possible if we need to get a new slab or have
 * debugging enabled (which means all slabs are marked with PageError)
 */
Christoph Lameter's avatar
Christoph Lameter committed
1179
1180
static void *slab_alloc(struct kmem_cache *s,
				gfp_t gfpflags, int node, void *addr)
Christoph Lameter's avatar
Christoph Lameter committed
1181
1182
1183
1184
1185
1186
1187
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
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
{
	struct page *page;
	void **object;
	unsigned long flags;
	int cpu;

	local_irq_save(flags);
	cpu = smp_processor_id();
	page = s->cpu_slab[cpu];
	if (!page)
		goto new_slab;

	slab_lock(page);
	if (unlikely(node != -1 && page_to_nid(page) != node))
		goto another_slab;
redo:
	object = page->freelist;
	if (unlikely(!object))
		goto another_slab;
	if (unlikely(PageError(page)))
		goto debug;

have_object:
	page->inuse++;
	page->freelist = object[page->offset];
	slab_unlock(page);
	local_irq_restore(flags);
	return object;

another_slab:
	deactivate_slab(s, page, cpu);

new_slab:
	page = get_partial(s, gfpflags, node);
	if (likely(page)) {
have_slab:
		s->cpu_slab[cpu] = page;
		SetPageActive(page);
		goto redo;
	}

	page = new_slab(s, gfpflags, node);
	if (page) {
		cpu = smp_processor_id();
		if (s->cpu_slab[cpu]) {
			/*
			 * Someone else populated the cpu_slab while we enabled
			 * interrupts, or we have got scheduled on another cpu.
			 * The page may not be on the requested node.
			 */
			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);
				goto redo;
			}
			/* Dump the current slab */
			flush_slab(s, s->cpu_slab[cpu], cpu);
		}
		slab_lock(page);
		goto have_slab;
	}
	local_irq_restore(flags);
	return NULL;
debug:
	if (!alloc_object_checks(s, page, object))
		goto another_slab;
	if (s->flags & SLAB_STORE_USER)
Christoph Lameter's avatar
Christoph Lameter committed
1254
		set_track(s, object, TRACK_ALLOC, addr);
1255
1256
1257
1258
1259
1260
1261
	if (s->flags & SLAB_TRACE) {
		printk(KERN_INFO "TRACE %s alloc 0x%p inuse=%d fp=0x%p\n",
			s->name, object, page->inuse,
			page->freelist);
		dump_stack();
	}
	init_object(s, object, 1);
Christoph Lameter's avatar
Christoph Lameter committed
1262
1263
1264
1265
1266
	goto have_object;
}

void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
Christoph Lameter's avatar
Christoph Lameter committed
1267
	return slab_alloc(s, gfpflags, -1, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
1268
1269
1270
1271
1272
1273
}
EXPORT_SYMBOL(kmem_cache_alloc);

#ifdef CONFIG_NUMA
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
Christoph Lameter's avatar
Christoph Lameter committed
1274
	return slab_alloc(s, gfpflags, node, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
#endif

/*
 * The fastpath only writes the cacheline of the page struct and the first
 * cacheline of the object.
 *
 * No special cachelines need to be read
 */
Christoph Lameter's avatar
Christoph Lameter committed
1285
1286
static void slab_free(struct kmem_cache *s, struct page *page,
					void *x, void *addr)
Christoph Lameter's avatar
Christoph Lameter committed
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
{
	void *prior;
	void **object = (void *)x;
	unsigned long flags;

	local_irq_save(flags);
	slab_lock(page);

	if (unlikely(PageError(page)))
		goto debug;
checks_ok:
	prior = object[page->offset] = page->freelist;
	page->freelist = object;
	page->inuse--;

	if (unlikely(PageActive(page)))
		/*
		 * Cpu slabs are never on partial lists and are
		 * never freed.
		 */
		goto out_unlock;

	if (unlikely(!page->inuse))
		goto slab_empty;

	/*
	 * Objects left in the slab. If it
	 * was not on the partial list before
	 * then add it.
	 */
	if (unlikely(!prior))
Christoph Lameter's avatar
Christoph Lameter committed
1318
		add_partial(get_node(s, page_to_nid(page)), page);
Christoph Lameter's avatar
Christoph Lameter committed
1319
1320
1321
1322
1323
1324
1325
1326
1327

out_unlock:
	slab_unlock(page);
	local_irq_restore(flags);
	return;

slab_empty:
	if (prior)
		/*
1328
		 * Slab on the partial list.
Christoph Lameter's avatar
Christoph Lameter committed
1329
1330
1331
1332
1333
1334
1335
1336
1337
		 */
		remove_partial(s, page);

	slab_unlock(page);
	discard_slab(s, page);
	local_irq_restore(flags);
	return;

debug:
Christoph Lameter's avatar
Christoph Lameter committed
1338
1339
	if (!free_object_checks(s, page, x))
		goto out_unlock;
1340
1341
	if (!PageActive(page) && !page->freelist)
		remove_full(s, page);
Christoph Lameter's avatar
Christoph Lameter committed
1342
1343
	if (s->flags & SLAB_STORE_USER)
		set_track(s, x, TRACK_FREE, addr);
1344
1345
1346
1347
1348
1349
1350
1351
	if (s->flags & SLAB_TRACE) {
		printk(KERN_INFO "TRACE %s free 0x%p inuse=%d fp=0x%p\n",
			s->name, object, page->inuse,
			page->freelist);
		print_section("Object", (void *)object, s->objsize);
		dump_stack();
	}
	init_object(s, object, 0);
Christoph Lameter's avatar
Christoph Lameter committed
1352
	goto checks_ok;
Christoph Lameter's avatar
Christoph Lameter committed
1353
1354
1355
1356
}

void kmem_cache_free(struct kmem_cache *s, void *x)
{
Christoph Lameter's avatar
Christoph Lameter committed
1357
	struct page *page;
Christoph Lameter's avatar
Christoph Lameter committed
1358

1359
	page = virt_to_head_page(x);
Christoph Lameter's avatar
Christoph Lameter committed
1360

Christoph Lameter's avatar
Christoph Lameter committed
1361
	slab_free(s, page, x, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
1362
1363
1364
1365
1366
1367
}
EXPORT_SYMBOL(kmem_cache_free);

/* Figure out on which slab object the object resides */
static struct page *get_object_page(const void *x)
{
1368
	struct page *page = virt_to_head_page(x);
Christoph Lameter's avatar
Christoph Lameter committed
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
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
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485

	if (!PageSlab(page))
		return NULL;

	return page;
}

/*
 * kmem_cache_open produces objects aligned at "size" and the first object
 * is placed at offset 0 in the slab (We have no metainformation on the
 * slab, all slabs are in essence "off slab").
 *
 * In order to get the desired alignment one just needs to align the
 * size.
 *
 * Notice that the allocation order determines the sizes of the per cpu
 * caches. Each processor has always one slab available for allocations.
 * Increasing the allocation order reduces the number of times that slabs
 * must be moved on and off the partial lists and therefore may influence
 * locking overhead.
 *
 * The offset is used to relocate the free list link in each object. It is
 * therefore possible to move the free list link behind the object. This
 * is necessary for RCU to work properly and also useful for debugging.
 */

/*
 * Mininum / Maximum order of slab pages. This influences locking overhead
 * and slab fragmentation. A higher order reduces the number of partial slabs
 * and increases the number of allocations possible without having to
 * take the list_lock.
 */
static int slub_min_order;
static int slub_max_order = DEFAULT_MAX_ORDER;

/*
 * Minimum number of objects per slab. This is necessary in order to
 * reduce locking overhead. Similar to the queue size in SLAB.
 */
static int slub_min_objects = DEFAULT_MIN_OBJECTS;

/*
 * Merge control. If this is set then no merging of slab caches will occur.
 */
static int slub_nomerge;

/*
 * Debug settings:
 */
static int slub_debug;

static char *slub_debug_slabs;

/*
 * Calculate the order of allocation given an slab object size.
 *
 * The order of allocation has significant impact on other elements
 * of the system. Generally order 0 allocations should be preferred
 * since they do not cause fragmentation in the page allocator. Larger
 * objects may have problems with order 0 because there may be too much
 * space left unused in a slab. We go to a higher order if more than 1/8th
 * of the slab would be wasted.
 *
 * In order to reach satisfactory performance we must ensure that
 * a minimum number of objects is in one slab. Otherwise we may
 * generate too much activity on the partial lists. This is less a
 * concern for large slabs though. slub_max_order specifies the order
 * where we begin to stop considering the number of objects in a slab.
 *
 * Higher order allocations also allow the placement of more objects
 * in a slab and thereby reduce object handling overhead. If the user
 * has requested a higher mininum order then we start with that one
 * instead of zero.
 */
static int calculate_order(int size)
{
	int order;
	int rem;

	for (order = max(slub_min_order, fls(size - 1) - PAGE_SHIFT);
			order < MAX_ORDER; order++) {
		unsigned long slab_size = PAGE_SIZE << order;

		if (slub_max_order > order &&
				slab_size < slub_min_objects * size)
			continue;

		if (slab_size < size)
			continue;

		rem = slab_size % size;

		if (rem <= (PAGE_SIZE << order) / 8)
			break;

	}
	if (order >= MAX_ORDER)
		return -E2BIG;
	return order;
}

/*
 * Function to figure out which alignment to use from the
 * various ways of specifying it.
 */
static unsigned long calculate_alignment(unsigned long flags,
		unsigned long align, unsigned long size)
{
	/*
	 * If the user wants hardware cache aligned objects then
	 * follow that suggestion if the object is sufficiently
	 * large.
	 *
	 * The hardware cache alignment cannot override the
	 * specified alignment though. If that is greater
	 * then use it.
	 */
1486
	if ((flags & SLAB_HWCACHE_ALIGN) &&
1487
1488
			size > cache_line_size() / 2)
		return max_t(unsigned long, align, cache_line_size());
Christoph Lameter's avatar
Christoph Lameter committed
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501

	if (align < ARCH_SLAB_MINALIGN)
		return ARCH_SLAB_MINALIGN;

	return ALIGN(align, sizeof(void *));
}

static void init_kmem_cache_node(struct kmem_cache_node *n)
{
	n->nr_partial = 0;
	atomic_long_set(&n->nr_slabs, 0);
	spin_lock_init(&n->list_lock);
	INIT_LIST_HEAD(&n->partial);
1502
	INIT_LIST_HEAD(&n->full);
Christoph Lameter's avatar
Christoph Lameter committed
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
}

#ifdef CONFIG_NUMA
/*
 * No kmalloc_node yet so do it by hand. We know that this is the first
 * slab on the node for this slabcache. There are no concurrent accesses
 * possible.
 *
 * Note that this function only works on the kmalloc_node_cache
 * when allocating for the kmalloc_node_cache.
 */
static struct kmem_cache_node * __init early_kmem_cache_node_alloc(gfp_t gfpflags,
								int node)
{
	struct page *page;
	struct kmem_cache_node *n;

	BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));

	page = new_slab(kmalloc_caches, gfpflags | GFP_THISNODE, node);
	/* new_slab() disables interupts */
	local_irq_enable();

	BUG_ON(!page);
	n = page->freelist;
	BUG_ON(!n);
	page->freelist = get_freepointer(kmalloc_caches, n);
	page->inuse++;
	kmalloc_caches->node[node] = n;
	init_object(kmalloc_caches, n, 1);
	init_kmem_cache_node(n);
	atomic_long_inc(&n->nr_slabs);
Christoph Lameter's avatar
Christoph Lameter committed
1535
	add_partial(n, page);
Christoph Lameter's avatar
Christoph Lameter committed
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
	return n;
}

static void free_kmem_cache_nodes(struct kmem_cache *s)
{
	int node;

	for_each_online_node(node) {
		struct kmem_cache_node *n = s->node[node];
		if (n && n != &s->local_node)
			kmem_cache_free(kmalloc_caches, n);
		s->node[node] = NULL;
	}
}

static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
{
	int node;
	int local_node;

	if (slab_state >= UP)
		local_node = page_to_nid(virt_to_page(s));
	else
		local_node = 0;

	for_each_online_node(node) {
		struct kmem_cache_node *n;

		if (local_node == node)
			n = &s->local_node;
		else {
			if (slab_state == DOWN) {
				n = early_kmem_cache_node_alloc(gfpflags,
								node);
				continue;
			}
			n = kmem_cache_alloc_node(kmalloc_caches,
							gfpflags, node);

			if (!n) {
				free_kmem_cache_nodes(s);
				return 0;
			}

		}
		s->node[node] = n;
		init_kmem_cache_node(n);
	}
	return 1;
}
#else
static void free_kmem_cache_nodes(struct kmem_cache *s)
{
}

static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
{
	init_kmem_cache_node(&s->local_node);
	return 1;
}
#endif

/*
 * calculate_sizes() determines the order and the distribution of data within
 * a slab object.
 */
static int calculate_sizes(struct kmem_cache *s)
{
	unsigned long flags = s->flags;
	unsigned long size = s->objsize;
	unsigned long align = s->align;

	/*
	 * Determine if we can poison the object itself. If the user of
	 * the slab may touch the object after free or before allocation
	 * then we should never poison the object itself.
	 */
	if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
			!s->ctor && !s->dtor)
		s->flags |= __OBJECT_POISON;
	else
		s->flags &= ~__OBJECT_POISON;

	/*
	 * Round up object size to the next word boundary. We can only
	 * place the free pointer at word boundaries and this determines
	 * the possible location of the free pointer.
	 */
	size = ALIGN(size, sizeof(void *));

	/*
	 * If we are redzoning then check if there is some space between the
	 * end of the object and the free pointer. If not then add an
	 * additional word, so that we can establish a redzone between
	 * the object and the freepointer to be able to check for overwrites.
	 */
	if ((flags & SLAB_RED_ZONE) && size == s->objsize)
		size += sizeof(void *);

	/*
	 * With that we have determined how much of the slab is in actual
	 * use by the object. This is the potential offset to the free
	 * pointer.
	 */
	s->inuse = size;

	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
		s->ctor || s->dtor)) {
		/*
		 * Relocate free pointer after the object if it is not
		 * permitted to overwrite the first word of the object on
		 * kmem_cache_free.
		 *
		 * This is the case if we do RCU, have a constructor or
		 * destructor or are poisoning the objects.
		 */
		s->offset = size;
		size += sizeof(void *);
	}

	if (flags & SLAB_STORE_USER)
		/*
		 * Need to store information about allocs and frees after
		 * the object.
		 */
		size += 2 * sizeof(struct track);

1663
	if (flags & SLAB_RED_ZONE)
Christoph Lameter's avatar
Christoph Lameter committed
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
		/*
		 * Add some empty padding so that we can catch
		 * overwrites from earlier objects rather than let
		 * tracking information or the free pointer be
		 * corrupted if an user writes before the start
		 * of the object.
		 */
		size += sizeof(void *);
	/*
	 * Determine the alignment based on various parameters that the
1674
1675
	 * user specified and the dynamic determination of cache line size
	 * on bootup.
Christoph Lameter's avatar
Christoph Lameter committed
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
	 */
	align = calculate_alignment(flags, align, s->objsize);

	/*
	 * SLUB stores one object immediately after another beginning from
	 * offset 0. In order to align the objects we have to simply size
	 * each object to conform to the alignment.
	 */
	size = ALIGN(size, align);
	s->size = size;

	s->order = calculate_order(size);
	if (s->order < 0)
		return 0;

	/*
	 * Determine the number of objects per slab
	 */
	s->objects = (PAGE_SIZE << s->order) / size;

	/*
	 * Verify that the number of objects is within permitted limits.
	 * The page->inuse field is only 16 bit wide! So we cannot have
	 * more than 64k objects per slab.
	 */
	if (!s->objects || s->objects > 65535)
		return 0;
	return 1;

}

static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
		const char *name, size_t size,
		size_t align, unsigned long flags,
		void (*ctor)(void *, struct kmem_cache *, unsigned long),
		void (*dtor)(void *, struct kmem_cache *, unsigned long))
{
	memset(s, 0, kmem_size);
	s->name = name;
	s->ctor = ctor;
	s->dtor = dtor;
	s->objsize = size;
	s->flags = flags;
	s->align = align;

	/*
	 * 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.
	 *
	 * Debugging or ctor/dtors may create a need to move the free
	 * pointer. Fail if this happens.
	 */
	if (s->size >= 65535 * sizeof(void *)) {
		BUG_ON(flags & (SLAB_RED_ZONE | SLAB_POISON |
				SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));
		BUG_ON(ctor || dtor);
	}
	else
		/*
		 * Enable debugging if selected on the kernel commandline.
		 */
		if (slub_debug && (!slub_debug_slabs ||
		    strncmp(slub_debug_slabs, name,
		    	strlen(slub_debug_slabs)) == 0))
				s->flags |= slub_debug;

	if (!calculate_sizes(s))
		goto error;

	s->refcount = 1;
#ifdef CONFIG_NUMA
	s->defrag_ratio = 100;
#endif

	if (init_kmem_cache_nodes(s, gfpflags & ~SLUB_DMA))
		return 1;
error:
	if (flags & SLAB_PANIC)
		panic("Cannot create slab %s size=%lu realsize=%u "
			"order=%u offset=%u flags=%lx\n",
			s->name, (unsigned long)size, s->size, s->order,
			s->offset, flags);
	return 0;
}
EXPORT_SYMBOL(kmem_cache_open);

/*
 * Check if a given pointer is valid
 */
int kmem_ptr_validate(struct kmem_cache *s, const void *object)
{
	struct page * page;
	void *addr;

	page = get_object_page(object);

	if (!page || s != page->slab)
		/* No slab or wrong slab */
		return 0;

1781
	if (!check_valid_pointer(s, page, object))
Christoph Lameter's avatar
Christoph Lameter committed
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
		return 0;

	/*
	 * We could also check if the object is on the slabs freelist.
	 * But this would be too expensive and it seems that the main
	 * purpose of kmem_ptr_valid is to check if the object belongs
	 * to a certain slab.
	 */
	return 1;
}
EXPORT_SYMBOL(kmem_ptr_validate);

/*
 * Determine the size of a slab object
 */
unsigned int kmem_cache_size(struct kmem_cache *s)
{
	return s->objsize;
}
EXPORT_SYMBOL(kmem_cache_size);

const char *kmem_cache_name(struct kmem_cache *s)
{
	return s->name;
}
EXPORT_SYMBOL(kmem_cache_name);

/*
 * Attempt to free all slabs on a node
 */
static int free_list(struct kmem_cache *s, struct kmem_cache_node *n,
			struct list_head *list)
{
	int slabs_inuse = 0;
	unsigned long flags;
	struct page *page, *h;

	spin_lock_irqsave(&n->list_lock, flags);
	list_for_each_entry_safe(page, h, list, lru)
		if (!page->inuse) {
			list_del(&page->lru);
			discard_slab(s, page);
		} else
			slabs_inuse++;
	spin_unlock_irqrestore(&n->list_lock, flags);
	return slabs_inuse;
}

/*
 * Release all resources used by slab cache
 */
static int kmem_cache_close(struct kmem_cache *s)
{
	int node;

	flush_all(s);

	/* Attempt to free all objects */
	for_each_online_node(node) {
		struct kmem_cache_node *n = get_node(s, node);

1843
		n->nr_partial -= free_list(s, n, &n->partial);
Christoph Lameter's avatar
Christoph Lameter committed
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
		if (atomic_long_read(&n->nr_slabs))
			return 1;
	}
	free_kmem_cache_nodes(s);
	return 0;
}

/*
 * Close a cache and release the kmem_cache structure
 * (must be used for caches created using kmem_cache_create)
 */
void kmem_cache_destroy(struct kmem_cache *s)
{
	down_write(&slub_lock);
	s->refcount--;
	if (!s->refcount) {
		list_del(&s->list);
		if (kmem_cache_close(s))
			WARN_ON(1);
		sysfs_slab_remove(s);
		kfree(s);
	}
	up_write(&slub_lock);
}
EXPORT_SYMBOL(kmem_cache_destroy);

/********************************************************************
 *		Kmalloc subsystem
 *******************************************************************/

struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1] __cacheline_aligned;
EXPORT_SYMBOL(kmalloc_caches);

#ifdef CONFIG_ZONE_DMA
static struct kmem_cache *kmalloc_caches_dma[KMALLOC_SHIFT_HIGH + 1];
#endif

static int __init setup_slub_min_order(char *str)
{
	get_option (&str, &slub_min_order);

	return 1;
}

__setup("slub_min_order=", setup_slub_min_order);

static int __init setup_slub_max_order(char *str)
{
	get_option (&str, &slub_max_order);

	return 1;
}

__setup("slub_max_order=", setup_slub_max_order);

static int __init setup_slub_min_objects(char *str)
{
	get_option (&str, &slub_min_objects);

	return 1;
}

__setup("slub_min_objects=", setup_slub_min_objects);

static int __init setup_slub_nomerge(char *str)
{
	slub_nomerge = 1;
	return 1;
}

__setup("slub_nomerge", setup_slub_nomerge);

static int __init setup_slub_debug(char *str)
{
	if (!str || *str != '=')
		slub_debug = DEBUG_DEFAULT_FLAGS;
	else {
		str++;
		if (*str == 0 || *str == ',')
			slub_debug = DEBUG_DEFAULT_FLAGS;
		else
		for( ;*str && *str != ','; str++)
			switch (*str) {
			case 'f' : case 'F' :
				slub_debug |= SLAB_DEBUG_FREE;
				break;
			case 'z' : case 'Z' :
				slub_debug |= SLAB_RED_ZONE;
				break;
			case 'p' : case 'P' :
				slub_debug |= SLAB_POISON;
				break;
			case 'u' : case 'U' :
				slub_debug |= SLAB_STORE_USER;
				break;
			case 't' : case 'T' :
				slub_debug |= SLAB_TRACE;
				break;
			default:
				printk(KERN_ERR "slub_debug option '%c' "
					"unknown. skipped\n",*str);
			}
	}

	if (*str == ',')
		slub_debug_slabs = str + 1;
	return 1;
}

__setup("slub_debug", setup_slub_debug);

static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,
		const char *name, int size, gfp_t gfp_flags)
{
	unsigned int flags = 0;

	if (gfp_flags & SLUB_DMA)
		flags = SLAB_CACHE_DMA;

	down_write(&slub_lock);
	if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
			flags, NULL, NULL))
		goto panic;

	list_add(&s->list, &slab_caches);
	up_write(&slub_lock);
	if (sysfs_slab_add(s))
		goto panic;
	return s;

panic:
	panic("Creation of kmalloc slab %s size=%d failed.\n", name, size);
}

static struct kmem_cache *get_slab(size_t size, gfp_t flags)
{
	int index = kmalloc_index(size);

1982
	if (!index)
Christoph Lameter's avatar
Christoph Lameter committed
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
		return NULL;

	/* Allocation too large? */
	BUG_ON(index < 0);

#ifdef CONFIG_ZONE_DMA
	if ((flags & SLUB_DMA)) {
		struct kmem_cache *s;
		struct kmem_cache *x;
		char *text;
		size_t realsize;

		s = kmalloc_caches_dma[index];
		if (s)
			return s;

		/* Dynamically create dma cache */
		x = kmalloc(kmem_size, flags & ~SLUB_DMA);
		if (!x)
			panic("Unable to allocate memory for dma cache\n");

		if (index <= KMALLOC_SHIFT_HIGH)
			realsize = 1 << index;
		else {
			if (index == 1)
				realsize = 96;
			else
				realsize = 192;
		}

		text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
				(unsigned int)realsize);
		s = create_kmalloc_cache(x, text, realsize, flags);
		kmalloc_caches_dma[index] = s;
		return s;
	}
#endif
	return &kmalloc_caches[index];
}

void *__kmalloc(size_t size, gfp_t flags)
{
	struct kmem_cache *s = get_slab(size, flags);

	if (s)
Christoph Lameter's avatar
Christoph Lameter committed
2028
		return slab_alloc(s, flags, -1, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
	return NULL;
}
EXPORT_SYMBOL(__kmalloc);

#ifdef CONFIG_NUMA
void *__kmalloc_node(size_t size, gfp_t flags, int node)
{
	struct kmem_cache *s = get_slab(size, flags);

	if (s)
Christoph Lameter's avatar
Christoph Lameter committed
2039
		return slab_alloc(s, flags, node, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
	return NULL;
}
EXPORT_SYMBOL(__kmalloc_node);
#endif

size_t ksize(const void *object)
{
	struct page *page = get_object_page(object);
	struct kmem_cache *s;

	BUG_ON(!page);
	s = page->slab;
	BUG_ON(!s);

	/*
	 * Debugging requires use of the padding between object
	 * and whatever may come after it.
	 */
	if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
		return s->objsize;

	/*
	 * If we have the need to store the freelist pointer
	 * back there or track user information then we can
	 * only use the space before that information.
	 */
	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
		return s->inuse;

	/*
	 * Else we can use all the padding etc for the allocation
	 */
	return s->size;
}
EXPORT_SYMBOL(ksize);

void kfree(const void *x)
{
	struct kmem_cache *s;
	struct page *page;

	if (!x)
		return;

2084
	page = virt_to_head_page(x);
Christoph Lameter's avatar
Christoph Lameter committed
2085
2086
	s = page->slab;

Christoph Lameter's avatar
Christoph Lameter committed
2087
	slab_free(s, page, (void *)x, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
2088
2089
2090
}
EXPORT_SYMBOL(kfree);

2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
/*
 *  kmem_cache_shrink removes empty slabs from the partial lists
 *  and then sorts the partially allocated slabs by the number
 *  of items in use. The slabs with the most items in use
 *  come first. New allocations will remove these from the
 *  partial list because they are full. The slabs with the
 *  least items are placed last. If it happens that the objects
 *  are freed then the page can be returned to the page allocator.
 */
int kmem_cache_shrink(struct kmem_cache *s)
{
	int node;
	int i;
	struct kmem_cache_node *n;
	struct page *page;
	struct page *t;
	struct list_head *slabs_by_inuse =
		kmalloc(sizeof(struct list_head) * s->objects, GFP_KERNEL);
	unsigned long flags;

	if (!slabs_by_inuse)
		return -ENOMEM;

	flush_all(s);
	for_each_online_node(node) {
		n = get_node(s, node);

		if (!n->nr_partial)
			continue;

		for (i = 0; i < s->objects; i++)
			INIT_LIST_HEAD(slabs_by_inuse + i);

		spin_lock_irqsave(&n->list_lock, flags);

		/*
		 * Build lists indexed by the items in use in
		 * each slab or free slabs if empty.
		 *
		 * Note that concurrent frees may occur while
		 * we hold the list_lock. page->inuse here is
		 * the upper limit.
		 */
		list_for_each_entry_safe(page, t, &n->partial, lru) {
			if (!page->inuse && slab_trylock(page)) {
				/*
				 * Must hold slab lock here because slab_free
				 * may have freed the last object and be
				 * waiting to release the slab.
				 */
				list_del(&page->lru);
				n->nr_partial--;
				slab_unlock(page);
				discard_slab(s, page);
			} else {
				if (n->nr_partial > MAX_PARTIAL)
					list_move(&page->lru,
					slabs_by_inuse + page->inuse);
			}
		}

		if (n->nr_partial <= MAX_PARTIAL)
			goto out;

		/*
		 * Rebuild the partial list with the slabs filled up
		 * most first and the least used slabs at the end.
		 */
		for (i = s->objects - 1; i >= 0; i--)
			list_splice(slabs_by_inuse + i, n->partial.prev);

	out:
		spin_unlock_irqrestore(&n->list_lock, flags);
	}

	kfree(slabs_by_inuse);
	return 0;
}
EXPORT_SYMBOL(kmem_cache_shrink);

Christoph Lameter's avatar
Christoph Lameter committed
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
/**
 * krealloc - reallocate memory. The contents will remain unchanged.
 *
 * @p: object to reallocate memory for.
 * @new_size: how many bytes of memory are required.
 * @flags: the type of memory to allocate.
 *
 * The contents of the object pointed to are preserved up to the
 * lesser of the new and old sizes.  If @p is %NULL, krealloc()
 * behaves exactly like kmalloc().  If @size is 0 and @p is not a
 * %NULL pointer, the object pointed to is freed.
 */
void *krealloc(const void *p, size_t new_size, gfp_t flags)
{
	void *ret;
Christoph Lameter's avatar
Christoph Lameter committed
2186
	size_t ks;
Christoph Lameter's avatar
Christoph Lameter committed
2187
2188
2189
2190
2191
2192
2193
2194
2195

	if (unlikely(!p))
		return kmalloc(new_size, flags);

	if (unlikely(!new_size)) {
		kfree(p);
		return NULL;
	}

Christoph Lameter's avatar
Christoph Lameter committed
2196
2197
	ks = ksize(p);
	if (ks >= new_size)
Christoph Lameter's avatar
Christoph Lameter committed
2198
2199
2200
2201
		return (void *)p;

	ret = kmalloc(new_size, flags);
	if (ret) {
Christoph Lameter's avatar
Christoph Lameter committed
2202
		memcpy(ret, p, min(new_size, ks));
Christoph Lameter's avatar
Christoph Lameter committed
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
		kfree(p);
	}
	return ret;
}
EXPORT_SYMBOL(krealloc);

/********************************************************************
 *			Basic setup of slabs
 *******************************************************************/

void __init kmem_cache_init(void)
{
	int i;

#ifdef CONFIG_NUMA
	/*
	 * Must first have the slab cache available for the allocations of the
	 * struct kmalloc_cache_node's. There is special bootstrap code in
	 * kmem_cache_open for slab_state == DOWN.
	 */
	create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
		sizeof(struct kmem_cache_node), GFP_KERNEL);
#endif

	/* Able to allocate the per node structures */
	slab_state = PARTIAL;

	/* Caches that are not of the two-to-the-power-of size */
	create_kmalloc_cache(&kmalloc_caches[1],
				"kmalloc-96", 96, GFP_KERNEL);
	create_kmalloc_cache(&kmalloc_caches[2],
				"kmalloc-192", 192, GFP_KERNEL);

	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
		create_kmalloc_cache(&kmalloc_caches[i],
			"kmalloc", 1 << i, GFP_KERNEL);

	slab_state = UP;

	/* Provide the correct kmalloc names now that the caches are up */
	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
		kmalloc_caches[i]. name =
			kasprintf(GFP_KERNEL, "kmalloc-%d", 1 << i);

#ifdef CONFIG_SMP
	register_cpu_notifier(&slab_notifier);
#endif

	if (nr_cpu_ids)	/* Remove when nr_cpu_ids is fixed upstream ! */
		kmem_size = offsetof(struct kmem_cache, cpu_slab)
			 + nr_cpu_ids * sizeof(struct page *);

	printk(KERN_INFO "SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d,"
		" Processors=%d, Nodes=%d\n",
2257
		KMALLOC_SHIFT_HIGH, cache_line_size(),
Christoph Lameter's avatar
Christoph Lameter committed
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
		slub_min_order, slub_max_order, slub_min_objects,
		nr_cpu_ids, nr_node_ids);
}

/*
 * Find a mergeable slab cache
 */
static int slab_unmergeable(struct kmem_cache *s)
{
	if (slub_nomerge || (s->flags & SLUB_NEVER_MERGE))
		return 1;

	if (s->ctor || s->dtor)
		return 1;

	return 0;
}

static struct kmem_cache *find_mergeable(size_t size,
		size_t align, unsigned long flags,
		void (*ctor)(void *, struct kmem_cache *, unsigned long),
		void (*dtor)(void *, struct kmem_cache *, unsigned long))
{
	struct list_head *h;

	if (slub_nomerge || (flags & SLUB_NEVER_MERGE))
		return NULL;

	if (ctor || dtor)
		return NULL;

	size = ALIGN(size, sizeof(void *));
	align = calculate_alignment(flags, align, size);
	size = ALIGN(size, align);

	list_for_each(h, &slab_caches) {
		struct kmem_cache *s =
			container_of(h, struct kmem_cache, list);

		if (slab_unmergeable(s))
			continue;

		if (size > s->size)
			continue;

		if (((flags | slub_debug) & SLUB_MERGE_SAME) !=
			(s->flags & SLUB_MERGE_SAME))
				continue;
		/*
		 * Check if alignment is compatible.
		 * Courtesy of Adrian Drzewiecki
		 */
		if ((s->size & ~(align -1)) != s->size)
			continue;

		if (s->size - size >= sizeof(void *))
			continue;

		return s;
	}
	return NULL;
}

struct kmem_cache *kmem_cache_create(const char *name, size_t size,
		size_t align, unsigned long flags,
		void (*ctor)(void *, struct kmem_cache *, unsigned long),
		void (*dtor)(void *, struct kmem_cache *, unsigned long))
{
	struct kmem_cache *s;

	down_write(&slub_lock);
	s = find_mergeable(size, align, flags, dtor, ctor);
	if (s) {
		s->refcount++;
		/*
		 * Adjust the object sizes so that we clear
		 * the complete object on kzalloc.
		 */
		s->objsize = max(s->objsize, (int)size);
		s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
		if (sysfs_slab_alias(s, name))
			goto err;
	} else {
		s = kmalloc(kmem_size, GFP_KERNEL);
		if (s && kmem_cache_open(s, GFP_KERNEL, name,
				size, align, flags, ctor, dtor)) {
			if (sysfs_slab_add(s)) {
				kfree(s);
				goto err;
			}
			list_add(&s->list, &slab_caches);
		} else
			kfree(s);
	}
	up_write(&slub_lock);
	return s;

err:
	up_write(&slub_lock);
	if (flags & SLAB_PANIC)
		panic("Cannot create slabcache %s\n", name);
	else
		s = NULL;
	return s;
}
EXPORT_SYMBOL(kmem_cache_create);

void *kmem_cache_zalloc(struct kmem_cache *s, gfp_t flags)
{
	void *x;

Christoph Lameter's avatar
Christoph Lameter committed
2369
	x = slab_alloc(s, flags, -1, __builtin_return_address(0));
Christoph Lameter's avatar
Christoph Lameter committed
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556