xref: /openbmc/linux/mm/slub.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * SLUB: A slab allocator that limits cache line use instead of queuing
3  * objects in per cpu and per node lists.
4  *
5  * The allocator synchronizes using per slab locks and only
6  * uses a centralized lock to manage a pool of partial slabs.
7  *
8  * (C) 2007 SGI, Christoph Lameter <clameter@sgi.com>
9  */
10 
11 #include <linux/mm.h>
12 #include <linux/module.h>
13 #include <linux/bit_spinlock.h>
14 #include <linux/interrupt.h>
15 #include <linux/bitops.h>
16 #include <linux/slab.h>
17 #include <linux/seq_file.h>
18 #include <linux/cpu.h>
19 #include <linux/cpuset.h>
20 #include <linux/mempolicy.h>
21 #include <linux/ctype.h>
22 #include <linux/kallsyms.h>
23 
24 /*
25  * Lock order:
26  *   1. slab_lock(page)
27  *   2. slab->list_lock
28  *
29  *   The slab_lock protects operations on the object of a particular
30  *   slab and its metadata in the page struct. If the slab lock
31  *   has been taken then no allocations nor frees can be performed
32  *   on the objects in the slab nor can the slab be added or removed
33  *   from the partial or full lists since this would mean modifying
34  *   the page_struct of the slab.
35  *
36  *   The list_lock protects the partial and full list on each node and
37  *   the partial slab counter. If taken then no new slabs may be added or
38  *   removed from the lists nor make the number of partial slabs be modified.
39  *   (Note that the total number of slabs is an atomic value that may be
40  *   modified without taking the list lock).
41  *
42  *   The list_lock is a centralized lock and thus we avoid taking it as
43  *   much as possible. As long as SLUB does not have to handle partial
44  *   slabs, operations can continue without any centralized lock. F.e.
45  *   allocating a long series of objects that fill up slabs does not require
46  *   the list lock.
47  *
48  *   The lock order is sometimes inverted when we are trying to get a slab
49  *   off a list. We take the list_lock and then look for a page on the list
50  *   to use. While we do that objects in the slabs may be freed. We can
51  *   only operate on the slab if we have also taken the slab_lock. So we use
52  *   a slab_trylock() on the slab. If trylock was successful then no frees
53  *   can occur anymore and we can use the slab for allocations etc. If the
54  *   slab_trylock() does not succeed then frees are in progress in the slab and
55  *   we must stay away from it for a while since we may cause a bouncing
56  *   cacheline if we try to acquire the lock. So go onto the next slab.
57  *   If all pages are busy then we may allocate a new slab instead of reusing
58  *   a partial slab. A new slab has noone operating on it and thus there is
59  *   no danger of cacheline contention.
60  *
61  *   Interrupts are disabled during allocation and deallocation in order to
62  *   make the slab allocator safe to use in the context of an irq. In addition
63  *   interrupts are disabled to ensure that the processor does not change
64  *   while handling per_cpu slabs, due to kernel preemption.
65  *
66  * SLUB assigns one slab for allocation to each processor.
67  * Allocations only occur from these slabs called cpu slabs.
68  *
69  * Slabs with free elements are kept on a partial list and during regular
70  * operations no list for full slabs is used. If an object in a full slab is
71  * freed then the slab will show up again on the partial lists.
72  * We track full slabs for debugging purposes though because otherwise we
73  * cannot scan all objects.
74  *
75  * Slabs are freed when they become empty. Teardown and setup is
76  * minimal so we rely on the page allocators per cpu caches for
77  * fast frees and allocs.
78  *
79  * Overloading of page flags that are otherwise used for LRU management.
80  *
81  * PageActive 		The slab is used as a cpu cache. Allocations
82  * 			may be performed from the slab. The slab is not
83  * 			on any slab list and cannot be moved onto one.
84  * 			The cpu slab may be equipped with an additioanl
85  * 			lockless_freelist that allows lockless access to
86  * 			free objects in addition to the regular freelist
87  * 			that requires the slab lock.
88  *
89  * PageError		Slab requires special handling due to debug
90  * 			options set. This moves	slab handling out of
91  * 			the fast path and disables lockless freelists.
92  */
93 
94 static inline int SlabDebug(struct page *page)
95 {
96 #ifdef CONFIG_SLUB_DEBUG
97 	return PageError(page);
98 #else
99 	return 0;
100 #endif
101 }
102 
103 static inline void SetSlabDebug(struct page *page)
104 {
105 #ifdef CONFIG_SLUB_DEBUG
106 	SetPageError(page);
107 #endif
108 }
109 
110 static inline void ClearSlabDebug(struct page *page)
111 {
112 #ifdef CONFIG_SLUB_DEBUG
113 	ClearPageError(page);
114 #endif
115 }
116 
117 /*
118  * Issues still to be resolved:
119  *
120  * - The per cpu array is updated for each new slab and and is a remote
121  *   cacheline for most nodes. This could become a bouncing cacheline given
122  *   enough frequent updates. There are 16 pointers in a cacheline, so at
123  *   max 16 cpus could compete for the cacheline which may be okay.
124  *
125  * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
126  *
127  * - Variable sizing of the per node arrays
128  */
129 
130 /* Enable to test recovery from slab corruption on boot */
131 #undef SLUB_RESILIENCY_TEST
132 
133 #if PAGE_SHIFT <= 12
134 
135 /*
136  * Small page size. Make sure that we do not fragment memory
137  */
138 #define DEFAULT_MAX_ORDER 1
139 #define DEFAULT_MIN_OBJECTS 4
140 
141 #else
142 
143 /*
144  * Large page machines are customarily able to handle larger
145  * page orders.
146  */
147 #define DEFAULT_MAX_ORDER 2
148 #define DEFAULT_MIN_OBJECTS 8
149 
150 #endif
151 
152 /*
153  * Mininum number of partial slabs. These will be left on the partial
154  * lists even if they are empty. kmem_cache_shrink may reclaim them.
155  */
156 #define MIN_PARTIAL 2
157 
158 /*
159  * Maximum number of desirable partial slabs.
160  * The existence of more partial slabs makes kmem_cache_shrink
161  * sort the partial list by the number of objects in the.
162  */
163 #define MAX_PARTIAL 10
164 
165 #define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
166 				SLAB_POISON | SLAB_STORE_USER)
167 
168 /*
169  * Set of flags that will prevent slab merging
170  */
171 #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
172 		SLAB_TRACE | SLAB_DESTROY_BY_RCU)
173 
174 #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
175 		SLAB_CACHE_DMA)
176 
177 #ifndef ARCH_KMALLOC_MINALIGN
178 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
179 #endif
180 
181 #ifndef ARCH_SLAB_MINALIGN
182 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
183 #endif
184 
185 /* Internal SLUB flags */
186 #define __OBJECT_POISON 0x80000000	/* Poison object */
187 
188 /* Not all arches define cache_line_size */
189 #ifndef cache_line_size
190 #define cache_line_size()	L1_CACHE_BYTES
191 #endif
192 
193 static int kmem_size = sizeof(struct kmem_cache);
194 
195 #ifdef CONFIG_SMP
196 static struct notifier_block slab_notifier;
197 #endif
198 
199 static enum {
200 	DOWN,		/* No slab functionality available */
201 	PARTIAL,	/* kmem_cache_open() works but kmalloc does not */
202 	UP,		/* Everything works but does not show up in sysfs */
203 	SYSFS		/* Sysfs up */
204 } slab_state = DOWN;
205 
206 /* A list of all slab caches on the system */
207 static DECLARE_RWSEM(slub_lock);
208 LIST_HEAD(slab_caches);
209 
210 /*
211  * Tracking user of a slab.
212  */
213 struct track {
214 	void *addr;		/* Called from address */
215 	int cpu;		/* Was running on cpu */
216 	int pid;		/* Pid context */
217 	unsigned long when;	/* When did the operation occur */
218 };
219 
220 enum track_item { TRACK_ALLOC, TRACK_FREE };
221 
222 #if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)
223 static int sysfs_slab_add(struct kmem_cache *);
224 static int sysfs_slab_alias(struct kmem_cache *, const char *);
225 static void sysfs_slab_remove(struct kmem_cache *);
226 #else
227 static int sysfs_slab_add(struct kmem_cache *s) { return 0; }
228 static int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; }
229 static void sysfs_slab_remove(struct kmem_cache *s) {}
230 #endif
231 
232 /********************************************************************
233  * 			Core slab cache functions
234  *******************************************************************/
235 
236 int slab_is_available(void)
237 {
238 	return slab_state >= UP;
239 }
240 
241 static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
242 {
243 #ifdef CONFIG_NUMA
244 	return s->node[node];
245 #else
246 	return &s->local_node;
247 #endif
248 }
249 
250 static inline int check_valid_pointer(struct kmem_cache *s,
251 				struct page *page, const void *object)
252 {
253 	void *base;
254 
255 	if (!object)
256 		return 1;
257 
258 	base = page_address(page);
259 	if (object < base || object >= base + s->objects * s->size ||
260 		(object - base) % s->size) {
261 		return 0;
262 	}
263 
264 	return 1;
265 }
266 
267 /*
268  * Slow version of get and set free pointer.
269  *
270  * This version requires touching the cache lines of kmem_cache which
271  * we avoid to do in the fast alloc free paths. There we obtain the offset
272  * from the page struct.
273  */
274 static inline void *get_freepointer(struct kmem_cache *s, void *object)
275 {
276 	return *(void **)(object + s->offset);
277 }
278 
279 static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
280 {
281 	*(void **)(object + s->offset) = fp;
282 }
283 
284 /* Loop over all objects in a slab */
285 #define for_each_object(__p, __s, __addr) \
286 	for (__p = (__addr); __p < (__addr) + (__s)->objects * (__s)->size;\
287 			__p += (__s)->size)
288 
289 /* Scan freelist */
290 #define for_each_free_object(__p, __s, __free) \
291 	for (__p = (__free); __p; __p = get_freepointer((__s), __p))
292 
293 /* Determine object index from a given position */
294 static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
295 {
296 	return (p - addr) / s->size;
297 }
298 
299 #ifdef CONFIG_SLUB_DEBUG
300 /*
301  * Debug settings:
302  */
303 static int slub_debug;
304 
305 static char *slub_debug_slabs;
306 
307 /*
308  * Object debugging
309  */
310 static void print_section(char *text, u8 *addr, unsigned int length)
311 {
312 	int i, offset;
313 	int newline = 1;
314 	char ascii[17];
315 
316 	ascii[16] = 0;
317 
318 	for (i = 0; i < length; i++) {
319 		if (newline) {
320 			printk(KERN_ERR "%10s 0x%p: ", text, addr + i);
321 			newline = 0;
322 		}
323 		printk(" %02x", addr[i]);
324 		offset = i % 16;
325 		ascii[offset] = isgraph(addr[i]) ? addr[i] : '.';
326 		if (offset == 15) {
327 			printk(" %s\n",ascii);
328 			newline = 1;
329 		}
330 	}
331 	if (!newline) {
332 		i %= 16;
333 		while (i < 16) {
334 			printk("   ");
335 			ascii[i] = ' ';
336 			i++;
337 		}
338 		printk(" %s\n", ascii);
339 	}
340 }
341 
342 static struct track *get_track(struct kmem_cache *s, void *object,
343 	enum track_item alloc)
344 {
345 	struct track *p;
346 
347 	if (s->offset)
348 		p = object + s->offset + sizeof(void *);
349 	else
350 		p = object + s->inuse;
351 
352 	return p + alloc;
353 }
354 
355 static void set_track(struct kmem_cache *s, void *object,
356 				enum track_item alloc, void *addr)
357 {
358 	struct track *p;
359 
360 	if (s->offset)
361 		p = object + s->offset + sizeof(void *);
362 	else
363 		p = object + s->inuse;
364 
365 	p += alloc;
366 	if (addr) {
367 		p->addr = addr;
368 		p->cpu = smp_processor_id();
369 		p->pid = current ? current->pid : -1;
370 		p->when = jiffies;
371 	} else
372 		memset(p, 0, sizeof(struct track));
373 }
374 
375 static void init_tracking(struct kmem_cache *s, void *object)
376 {
377 	if (s->flags & SLAB_STORE_USER) {
378 		set_track(s, object, TRACK_FREE, NULL);
379 		set_track(s, object, TRACK_ALLOC, NULL);
380 	}
381 }
382 
383 static void print_track(const char *s, struct track *t)
384 {
385 	if (!t->addr)
386 		return;
387 
388 	printk(KERN_ERR "%s: ", s);
389 	__print_symbol("%s", (unsigned long)t->addr);
390 	printk(" jiffies_ago=%lu cpu=%u pid=%d\n", jiffies - t->when, t->cpu, t->pid);
391 }
392 
393 static void print_trailer(struct kmem_cache *s, u8 *p)
394 {
395 	unsigned int off;	/* Offset of last byte */
396 
397 	if (s->flags & SLAB_RED_ZONE)
398 		print_section("Redzone", p + s->objsize,
399 			s->inuse - s->objsize);
400 
401 	printk(KERN_ERR "FreePointer 0x%p -> 0x%p\n",
402 			p + s->offset,
403 			get_freepointer(s, p));
404 
405 	if (s->offset)
406 		off = s->offset + sizeof(void *);
407 	else
408 		off = s->inuse;
409 
410 	if (s->flags & SLAB_STORE_USER) {
411 		print_track("Last alloc", get_track(s, p, TRACK_ALLOC));
412 		print_track("Last free ", get_track(s, p, TRACK_FREE));
413 		off += 2 * sizeof(struct track);
414 	}
415 
416 	if (off != s->size)
417 		/* Beginning of the filler is the free pointer */
418 		print_section("Filler", p + off, s->size - off);
419 }
420 
421 static void object_err(struct kmem_cache *s, struct page *page,
422 			u8 *object, char *reason)
423 {
424 	u8 *addr = page_address(page);
425 
426 	printk(KERN_ERR "*** SLUB %s: %s@0x%p slab 0x%p\n",
427 			s->name, reason, object, page);
428 	printk(KERN_ERR "    offset=%tu flags=0x%04lx inuse=%u freelist=0x%p\n",
429 		object - addr, page->flags, page->inuse, page->freelist);
430 	if (object > addr + 16)
431 		print_section("Bytes b4", object - 16, 16);
432 	print_section("Object", object, min(s->objsize, 128));
433 	print_trailer(s, object);
434 	dump_stack();
435 }
436 
437 static void slab_err(struct kmem_cache *s, struct page *page, char *reason, ...)
438 {
439 	va_list args;
440 	char buf[100];
441 
442 	va_start(args, reason);
443 	vsnprintf(buf, sizeof(buf), reason, args);
444 	va_end(args);
445 	printk(KERN_ERR "*** SLUB %s: %s in slab @0x%p\n", s->name, buf,
446 		page);
447 	dump_stack();
448 }
449 
450 static void init_object(struct kmem_cache *s, void *object, int active)
451 {
452 	u8 *p = object;
453 
454 	if (s->flags & __OBJECT_POISON) {
455 		memset(p, POISON_FREE, s->objsize - 1);
456 		p[s->objsize -1] = POISON_END;
457 	}
458 
459 	if (s->flags & SLAB_RED_ZONE)
460 		memset(p + s->objsize,
461 			active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE,
462 			s->inuse - s->objsize);
463 }
464 
465 static int check_bytes(u8 *start, unsigned int value, unsigned int bytes)
466 {
467 	while (bytes) {
468 		if (*start != (u8)value)
469 			return 0;
470 		start++;
471 		bytes--;
472 	}
473 	return 1;
474 }
475 
476 /*
477  * Object layout:
478  *
479  * object address
480  * 	Bytes of the object to be managed.
481  * 	If the freepointer may overlay the object then the free
482  * 	pointer is the first word of the object.
483  *
484  * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
485  * 	0xa5 (POISON_END)
486  *
487  * object + s->objsize
488  * 	Padding to reach word boundary. This is also used for Redzoning.
489  * 	Padding is extended by another word if Redzoning is enabled and
490  * 	objsize == inuse.
491  *
492  * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
493  * 	0xcc (RED_ACTIVE) for objects in use.
494  *
495  * object + s->inuse
496  * 	Meta data starts here.
497  *
498  * 	A. Free pointer (if we cannot overwrite object on free)
499  * 	B. Tracking data for SLAB_STORE_USER
500  * 	C. Padding to reach required alignment boundary or at mininum
501  * 		one word if debuggin is on to be able to detect writes
502  * 		before the word boundary.
503  *
504  *	Padding is done using 0x5a (POISON_INUSE)
505  *
506  * object + s->size
507  * 	Nothing is used beyond s->size.
508  *
509  * If slabcaches are merged then the objsize and inuse boundaries are mostly
510  * ignored. And therefore no slab options that rely on these boundaries
511  * may be used with merged slabcaches.
512  */
513 
514 static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
515 						void *from, void *to)
516 {
517 	printk(KERN_ERR "@@@ SLUB %s: Restoring %s (0x%x) from 0x%p-0x%p\n",
518 		s->name, message, data, from, to - 1);
519 	memset(from, data, to - from);
520 }
521 
522 static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
523 {
524 	unsigned long off = s->inuse;	/* The end of info */
525 
526 	if (s->offset)
527 		/* Freepointer is placed after the object. */
528 		off += sizeof(void *);
529 
530 	if (s->flags & SLAB_STORE_USER)
531 		/* We also have user information there */
532 		off += 2 * sizeof(struct track);
533 
534 	if (s->size == off)
535 		return 1;
536 
537 	if (check_bytes(p + off, POISON_INUSE, s->size - off))
538 		return 1;
539 
540 	object_err(s, page, p, "Object padding check fails");
541 
542 	/*
543 	 * Restore padding
544 	 */
545 	restore_bytes(s, "object padding", POISON_INUSE, p + off, p + s->size);
546 	return 0;
547 }
548 
549 static int slab_pad_check(struct kmem_cache *s, struct page *page)
550 {
551 	u8 *p;
552 	int length, remainder;
553 
554 	if (!(s->flags & SLAB_POISON))
555 		return 1;
556 
557 	p = page_address(page);
558 	length = s->objects * s->size;
559 	remainder = (PAGE_SIZE << s->order) - length;
560 	if (!remainder)
561 		return 1;
562 
563 	if (!check_bytes(p + length, POISON_INUSE, remainder)) {
564 		slab_err(s, page, "Padding check failed");
565 		restore_bytes(s, "slab padding", POISON_INUSE, p + length,
566 			p + length + remainder);
567 		return 0;
568 	}
569 	return 1;
570 }
571 
572 static int check_object(struct kmem_cache *s, struct page *page,
573 					void *object, int active)
574 {
575 	u8 *p = object;
576 	u8 *endobject = object + s->objsize;
577 
578 	if (s->flags & SLAB_RED_ZONE) {
579 		unsigned int red =
580 			active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE;
581 
582 		if (!check_bytes(endobject, red, s->inuse - s->objsize)) {
583 			object_err(s, page, object,
584 			active ? "Redzone Active" : "Redzone Inactive");
585 			restore_bytes(s, "redzone", red,
586 				endobject, object + s->inuse);
587 			return 0;
588 		}
589 	} else {
590 		if ((s->flags & SLAB_POISON) && s->objsize < s->inuse &&
591 			!check_bytes(endobject, POISON_INUSE,
592 					s->inuse - s->objsize)) {
593 		object_err(s, page, p, "Alignment padding check fails");
594 		/*
595 		 * Fix it so that there will not be another report.
596 		 *
597 		 * Hmmm... We may be corrupting an object that now expects
598 		 * to be longer than allowed.
599 		 */
600 		restore_bytes(s, "alignment padding", POISON_INUSE,
601 			endobject, object + s->inuse);
602 		}
603 	}
604 
605 	if (s->flags & SLAB_POISON) {
606 		if (!active && (s->flags & __OBJECT_POISON) &&
607 			(!check_bytes(p, POISON_FREE, s->objsize - 1) ||
608 				p[s->objsize - 1] != POISON_END)) {
609 
610 			object_err(s, page, p, "Poison check failed");
611 			restore_bytes(s, "Poison", POISON_FREE,
612 						p, p + s->objsize -1);
613 			restore_bytes(s, "Poison", POISON_END,
614 					p + s->objsize - 1, p + s->objsize);
615 			return 0;
616 		}
617 		/*
618 		 * check_pad_bytes cleans up on its own.
619 		 */
620 		check_pad_bytes(s, page, p);
621 	}
622 
623 	if (!s->offset && active)
624 		/*
625 		 * Object and freepointer overlap. Cannot check
626 		 * freepointer while object is allocated.
627 		 */
628 		return 1;
629 
630 	/* Check free pointer validity */
631 	if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
632 		object_err(s, page, p, "Freepointer corrupt");
633 		/*
634 		 * No choice but to zap it and thus loose the remainder
635 		 * of the free objects in this slab. May cause
636 		 * another error because the object count is now wrong.
637 		 */
638 		set_freepointer(s, p, NULL);
639 		return 0;
640 	}
641 	return 1;
642 }
643 
644 static int check_slab(struct kmem_cache *s, struct page *page)
645 {
646 	VM_BUG_ON(!irqs_disabled());
647 
648 	if (!PageSlab(page)) {
649 		slab_err(s, page, "Not a valid slab page flags=%lx "
650 			"mapping=0x%p count=%d", page->flags, page->mapping,
651 			page_count(page));
652 		return 0;
653 	}
654 	if (page->offset * sizeof(void *) != s->offset) {
655 		slab_err(s, page, "Corrupted offset %lu flags=0x%lx "
656 			"mapping=0x%p count=%d",
657 			(unsigned long)(page->offset * sizeof(void *)),
658 			page->flags,
659 			page->mapping,
660 			page_count(page));
661 		return 0;
662 	}
663 	if (page->inuse > s->objects) {
664 		slab_err(s, page, "inuse %u > max %u @0x%p flags=%lx "
665 			"mapping=0x%p count=%d",
666 			s->name, page->inuse, s->objects, page->flags,
667 			page->mapping, page_count(page));
668 		return 0;
669 	}
670 	/* Slab_pad_check fixes things up after itself */
671 	slab_pad_check(s, page);
672 	return 1;
673 }
674 
675 /*
676  * Determine if a certain object on a page is on the freelist. Must hold the
677  * slab lock to guarantee that the chains are in a consistent state.
678  */
679 static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
680 {
681 	int nr = 0;
682 	void *fp = page->freelist;
683 	void *object = NULL;
684 
685 	while (fp && nr <= s->objects) {
686 		if (fp == search)
687 			return 1;
688 		if (!check_valid_pointer(s, page, fp)) {
689 			if (object) {
690 				object_err(s, page, object,
691 					"Freechain corrupt");
692 				set_freepointer(s, object, NULL);
693 				break;
694 			} else {
695 				slab_err(s, page, "Freepointer 0x%p corrupt",
696 									fp);
697 				page->freelist = NULL;
698 				page->inuse = s->objects;
699 				printk(KERN_ERR "@@@ SLUB %s: Freelist "
700 					"cleared. Slab 0x%p\n",
701 					s->name, page);
702 				return 0;
703 			}
704 			break;
705 		}
706 		object = fp;
707 		fp = get_freepointer(s, object);
708 		nr++;
709 	}
710 
711 	if (page->inuse != s->objects - nr) {
712 		slab_err(s, page, "Wrong object count. Counter is %d but "
713 			"counted were %d", s, page, page->inuse,
714 							s->objects - nr);
715 		page->inuse = s->objects - nr;
716 		printk(KERN_ERR "@@@ SLUB %s: Object count adjusted. "
717 			"Slab @0x%p\n", s->name, page);
718 	}
719 	return search == NULL;
720 }
721 
722 /*
723  * Tracking of fully allocated slabs for debugging purposes.
724  */
725 static void add_full(struct kmem_cache_node *n, struct page *page)
726 {
727 	spin_lock(&n->list_lock);
728 	list_add(&page->lru, &n->full);
729 	spin_unlock(&n->list_lock);
730 }
731 
732 static void remove_full(struct kmem_cache *s, struct page *page)
733 {
734 	struct kmem_cache_node *n;
735 
736 	if (!(s->flags & SLAB_STORE_USER))
737 		return;
738 
739 	n = get_node(s, page_to_nid(page));
740 
741 	spin_lock(&n->list_lock);
742 	list_del(&page->lru);
743 	spin_unlock(&n->list_lock);
744 }
745 
746 static int alloc_object_checks(struct kmem_cache *s, struct page *page,
747 							void *object)
748 {
749 	if (!check_slab(s, page))
750 		goto bad;
751 
752 	if (object && !on_freelist(s, page, object)) {
753 		slab_err(s, page, "Object 0x%p already allocated", object);
754 		goto bad;
755 	}
756 
757 	if (!check_valid_pointer(s, page, object)) {
758 		object_err(s, page, object, "Freelist Pointer check fails");
759 		goto bad;
760 	}
761 
762 	if (!object)
763 		return 1;
764 
765 	if (!check_object(s, page, object, 0))
766 		goto bad;
767 
768 	return 1;
769 bad:
770 	if (PageSlab(page)) {
771 		/*
772 		 * If this is a slab page then lets do the best we can
773 		 * to avoid issues in the future. Marking all objects
774 		 * as used avoids touching the remaining objects.
775 		 */
776 		printk(KERN_ERR "@@@ SLUB: %s slab 0x%p. Marking all objects used.\n",
777 			s->name, page);
778 		page->inuse = s->objects;
779 		page->freelist = NULL;
780 		/* Fix up fields that may be corrupted */
781 		page->offset = s->offset / sizeof(void *);
782 	}
783 	return 0;
784 }
785 
786 static int free_object_checks(struct kmem_cache *s, struct page *page,
787 							void *object)
788 {
789 	if (!check_slab(s, page))
790 		goto fail;
791 
792 	if (!check_valid_pointer(s, page, object)) {
793 		slab_err(s, page, "Invalid object pointer 0x%p", object);
794 		goto fail;
795 	}
796 
797 	if (on_freelist(s, page, object)) {
798 		slab_err(s, page, "Object 0x%p already free", object);
799 		goto fail;
800 	}
801 
802 	if (!check_object(s, page, object, 1))
803 		return 0;
804 
805 	if (unlikely(s != page->slab)) {
806 		if (!PageSlab(page))
807 			slab_err(s, page, "Attempt to free object(0x%p) "
808 				"outside of slab", object);
809 		else
810 		if (!page->slab) {
811 			printk(KERN_ERR
812 				"SLUB <none>: no slab for object 0x%p.\n",
813 						object);
814 			dump_stack();
815 		}
816 		else
817 			slab_err(s, page, "object at 0x%p belongs "
818 				"to slab %s", object, page->slab->name);
819 		goto fail;
820 	}
821 	return 1;
822 fail:
823 	printk(KERN_ERR "@@@ SLUB: %s slab 0x%p object at 0x%p not freed.\n",
824 		s->name, page, object);
825 	return 0;
826 }
827 
828 static void trace(struct kmem_cache *s, struct page *page, void *object, int alloc)
829 {
830 	if (s->flags & SLAB_TRACE) {
831 		printk(KERN_INFO "TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
832 			s->name,
833 			alloc ? "alloc" : "free",
834 			object, page->inuse,
835 			page->freelist);
836 
837 		if (!alloc)
838 			print_section("Object", (void *)object, s->objsize);
839 
840 		dump_stack();
841 	}
842 }
843 
844 static int __init setup_slub_debug(char *str)
845 {
846 	if (!str || *str != '=')
847 		slub_debug = DEBUG_DEFAULT_FLAGS;
848 	else {
849 		str++;
850 		if (*str == 0 || *str == ',')
851 			slub_debug = DEBUG_DEFAULT_FLAGS;
852 		else
853 		for( ;*str && *str != ','; str++)
854 			switch (*str) {
855 			case 'f' : case 'F' :
856 				slub_debug |= SLAB_DEBUG_FREE;
857 				break;
858 			case 'z' : case 'Z' :
859 				slub_debug |= SLAB_RED_ZONE;
860 				break;
861 			case 'p' : case 'P' :
862 				slub_debug |= SLAB_POISON;
863 				break;
864 			case 'u' : case 'U' :
865 				slub_debug |= SLAB_STORE_USER;
866 				break;
867 			case 't' : case 'T' :
868 				slub_debug |= SLAB_TRACE;
869 				break;
870 			default:
871 				printk(KERN_ERR "slub_debug option '%c' "
872 					"unknown. skipped\n",*str);
873 			}
874 	}
875 
876 	if (*str == ',')
877 		slub_debug_slabs = str + 1;
878 	return 1;
879 }
880 
881 __setup("slub_debug", setup_slub_debug);
882 
883 static void kmem_cache_open_debug_check(struct kmem_cache *s)
884 {
885 	/*
886 	 * The page->offset field is only 16 bit wide. This is an offset
887 	 * in units of words from the beginning of an object. If the slab
888 	 * size is bigger then we cannot move the free pointer behind the
889 	 * object anymore.
890 	 *
891 	 * On 32 bit platforms the limit is 256k. On 64bit platforms
892 	 * the limit is 512k.
893 	 *
894 	 * Debugging or ctor/dtors may create a need to move the free
895 	 * pointer. Fail if this happens.
896 	 */
897 	if (s->size >= 65535 * sizeof(void *)) {
898 		BUG_ON(s->flags & (SLAB_RED_ZONE | SLAB_POISON |
899 				SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));
900 		BUG_ON(s->ctor || s->dtor);
901 	}
902 	else
903 		/*
904 		 * Enable debugging if selected on the kernel commandline.
905 		 */
906 		if (slub_debug && (!slub_debug_slabs ||
907 		    strncmp(slub_debug_slabs, s->name,
908 		    	strlen(slub_debug_slabs)) == 0))
909 				s->flags |= slub_debug;
910 }
911 #else
912 
913 static inline int alloc_object_checks(struct kmem_cache *s,
914 		struct page *page, void *object) { return 0; }
915 
916 static inline int free_object_checks(struct kmem_cache *s,
917 		struct page *page, void *object) { return 0; }
918 
919 static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
920 static inline void remove_full(struct kmem_cache *s, struct page *page) {}
921 static inline void trace(struct kmem_cache *s, struct page *page,
922 			void *object, int alloc) {}
923 static inline void init_object(struct kmem_cache *s,
924 			void *object, int active) {}
925 static inline void init_tracking(struct kmem_cache *s, void *object) {}
926 static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
927 			{ return 1; }
928 static inline int check_object(struct kmem_cache *s, struct page *page,
929 			void *object, int active) { return 1; }
930 static inline void set_track(struct kmem_cache *s, void *object,
931 			enum track_item alloc, void *addr) {}
932 static inline void kmem_cache_open_debug_check(struct kmem_cache *s) {}
933 #define slub_debug 0
934 #endif
935 /*
936  * Slab allocation and freeing
937  */
938 static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
939 {
940 	struct page * page;
941 	int pages = 1 << s->order;
942 
943 	if (s->order)
944 		flags |= __GFP_COMP;
945 
946 	if (s->flags & SLAB_CACHE_DMA)
947 		flags |= SLUB_DMA;
948 
949 	if (node == -1)
950 		page = alloc_pages(flags, s->order);
951 	else
952 		page = alloc_pages_node(node, flags, s->order);
953 
954 	if (!page)
955 		return NULL;
956 
957 	mod_zone_page_state(page_zone(page),
958 		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
959 		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
960 		pages);
961 
962 	return page;
963 }
964 
965 static void setup_object(struct kmem_cache *s, struct page *page,
966 				void *object)
967 {
968 	if (SlabDebug(page)) {
969 		init_object(s, object, 0);
970 		init_tracking(s, object);
971 	}
972 
973 	if (unlikely(s->ctor))
974 		s->ctor(object, s, SLAB_CTOR_CONSTRUCTOR);
975 }
976 
977 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
978 {
979 	struct page *page;
980 	struct kmem_cache_node *n;
981 	void *start;
982 	void *end;
983 	void *last;
984 	void *p;
985 
986 	BUG_ON(flags & ~(GFP_DMA | GFP_LEVEL_MASK));
987 
988 	if (flags & __GFP_WAIT)
989 		local_irq_enable();
990 
991 	page = allocate_slab(s, flags & GFP_LEVEL_MASK, node);
992 	if (!page)
993 		goto out;
994 
995 	n = get_node(s, page_to_nid(page));
996 	if (n)
997 		atomic_long_inc(&n->nr_slabs);
998 	page->offset = s->offset / sizeof(void *);
999 	page->slab = s;
1000 	page->flags |= 1 << PG_slab;
1001 	if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
1002 			SLAB_STORE_USER | SLAB_TRACE))
1003 		SetSlabDebug(page);
1004 
1005 	start = page_address(page);
1006 	end = start + s->objects * s->size;
1007 
1008 	if (unlikely(s->flags & SLAB_POISON))
1009 		memset(start, POISON_INUSE, PAGE_SIZE << s->order);
1010 
1011 	last = start;
1012 	for_each_object(p, s, start) {
1013 		setup_object(s, page, last);
1014 		set_freepointer(s, last, p);
1015 		last = p;
1016 	}
1017 	setup_object(s, page, last);
1018 	set_freepointer(s, last, NULL);
1019 
1020 	page->freelist = start;
1021 	page->lockless_freelist = NULL;
1022 	page->inuse = 0;
1023 out:
1024 	if (flags & __GFP_WAIT)
1025 		local_irq_disable();
1026 	return page;
1027 }
1028 
1029 static void __free_slab(struct kmem_cache *s, struct page *page)
1030 {
1031 	int pages = 1 << s->order;
1032 
1033 	if (unlikely(SlabDebug(page) || s->dtor)) {
1034 		void *p;
1035 
1036 		slab_pad_check(s, page);
1037 		for_each_object(p, s, page_address(page)) {
1038 			if (s->dtor)
1039 				s->dtor(p, s, 0);
1040 			check_object(s, page, p, 0);
1041 		}
1042 	}
1043 
1044 	mod_zone_page_state(page_zone(page),
1045 		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
1046 		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
1047 		- pages);
1048 
1049 	page->mapping = NULL;
1050 	__free_pages(page, s->order);
1051 }
1052 
1053 static void rcu_free_slab(struct rcu_head *h)
1054 {
1055 	struct page *page;
1056 
1057 	page = container_of((struct list_head *)h, struct page, lru);
1058 	__free_slab(page->slab, page);
1059 }
1060 
1061 static void free_slab(struct kmem_cache *s, struct page *page)
1062 {
1063 	if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
1064 		/*
1065 		 * RCU free overloads the RCU head over the LRU
1066 		 */
1067 		struct rcu_head *head = (void *)&page->lru;
1068 
1069 		call_rcu(head, rcu_free_slab);
1070 	} else
1071 		__free_slab(s, page);
1072 }
1073 
1074 static void discard_slab(struct kmem_cache *s, struct page *page)
1075 {
1076 	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
1077 
1078 	atomic_long_dec(&n->nr_slabs);
1079 	reset_page_mapcount(page);
1080 	ClearSlabDebug(page);
1081 	__ClearPageSlab(page);
1082 	free_slab(s, page);
1083 }
1084 
1085 /*
1086  * Per slab locking using the pagelock
1087  */
1088 static __always_inline void slab_lock(struct page *page)
1089 {
1090 	bit_spin_lock(PG_locked, &page->flags);
1091 }
1092 
1093 static __always_inline void slab_unlock(struct page *page)
1094 {
1095 	bit_spin_unlock(PG_locked, &page->flags);
1096 }
1097 
1098 static __always_inline int slab_trylock(struct page *page)
1099 {
1100 	int rc = 1;
1101 
1102 	rc = bit_spin_trylock(PG_locked, &page->flags);
1103 	return rc;
1104 }
1105 
1106 /*
1107  * Management of partially allocated slabs
1108  */
1109 static void add_partial_tail(struct kmem_cache_node *n, struct page *page)
1110 {
1111 	spin_lock(&n->list_lock);
1112 	n->nr_partial++;
1113 	list_add_tail(&page->lru, &n->partial);
1114 	spin_unlock(&n->list_lock);
1115 }
1116 
1117 static void add_partial(struct kmem_cache_node *n, struct page *page)
1118 {
1119 	spin_lock(&n->list_lock);
1120 	n->nr_partial++;
1121 	list_add(&page->lru, &n->partial);
1122 	spin_unlock(&n->list_lock);
1123 }
1124 
1125 static void remove_partial(struct kmem_cache *s,
1126 						struct page *page)
1127 {
1128 	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
1129 
1130 	spin_lock(&n->list_lock);
1131 	list_del(&page->lru);
1132 	n->nr_partial--;
1133 	spin_unlock(&n->list_lock);
1134 }
1135 
1136 /*
1137  * Lock slab and remove from the partial list.
1138  *
1139  * Must hold list_lock.
1140  */
1141 static int lock_and_del_slab(struct kmem_cache_node *n, struct page *page)
1142 {
1143 	if (slab_trylock(page)) {
1144 		list_del(&page->lru);
1145 		n->nr_partial--;
1146 		return 1;
1147 	}
1148 	return 0;
1149 }
1150 
1151 /*
1152  * Try to allocate a partial slab from a specific node.
1153  */
1154 static struct page *get_partial_node(struct kmem_cache_node *n)
1155 {
1156 	struct page *page;
1157 
1158 	/*
1159 	 * Racy check. If we mistakenly see no partial slabs then we
1160 	 * just allocate an empty slab. If we mistakenly try to get a
1161 	 * partial slab and there is none available then get_partials()
1162 	 * will return NULL.
1163 	 */
1164 	if (!n || !n->nr_partial)
1165 		return NULL;
1166 
1167 	spin_lock(&n->list_lock);
1168 	list_for_each_entry(page, &n->partial, lru)
1169 		if (lock_and_del_slab(n, page))
1170 			goto out;
1171 	page = NULL;
1172 out:
1173 	spin_unlock(&n->list_lock);
1174 	return page;
1175 }
1176 
1177 /*
1178  * Get a page from somewhere. Search in increasing NUMA distances.
1179  */
1180 static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
1181 {
1182 #ifdef CONFIG_NUMA
1183 	struct zonelist *zonelist;
1184 	struct zone **z;
1185 	struct page *page;
1186 
1187 	/*
1188 	 * The defrag ratio allows a configuration of the tradeoffs between
1189 	 * inter node defragmentation and node local allocations. A lower
1190 	 * defrag_ratio increases the tendency to do local allocations
1191 	 * instead of attempting to obtain partial slabs from other nodes.
1192 	 *
1193 	 * If the defrag_ratio is set to 0 then kmalloc() always
1194 	 * returns node local objects. If the ratio is higher then kmalloc()
1195 	 * may return off node objects because partial slabs are obtained
1196 	 * from other nodes and filled up.
1197 	 *
1198 	 * If /sys/slab/xx/defrag_ratio is set to 100 (which makes
1199 	 * defrag_ratio = 1000) then every (well almost) allocation will
1200 	 * first attempt to defrag slab caches on other nodes. This means
1201 	 * scanning over all nodes to look for partial slabs which may be
1202 	 * expensive if we do it every time we are trying to find a slab
1203 	 * with available objects.
1204 	 */
1205 	if (!s->defrag_ratio || get_cycles() % 1024 > s->defrag_ratio)
1206 		return NULL;
1207 
1208 	zonelist = &NODE_DATA(slab_node(current->mempolicy))
1209 					->node_zonelists[gfp_zone(flags)];
1210 	for (z = zonelist->zones; *z; z++) {
1211 		struct kmem_cache_node *n;
1212 
1213 		n = get_node(s, zone_to_nid(*z));
1214 
1215 		if (n && cpuset_zone_allowed_hardwall(*z, flags) &&
1216 				n->nr_partial > MIN_PARTIAL) {
1217 			page = get_partial_node(n);
1218 			if (page)
1219 				return page;
1220 		}
1221 	}
1222 #endif
1223 	return NULL;
1224 }
1225 
1226 /*
1227  * Get a partial page, lock it and return it.
1228  */
1229 static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
1230 {
1231 	struct page *page;
1232 	int searchnode = (node == -1) ? numa_node_id() : node;
1233 
1234 	page = get_partial_node(get_node(s, searchnode));
1235 	if (page || (flags & __GFP_THISNODE))
1236 		return page;
1237 
1238 	return get_any_partial(s, flags);
1239 }
1240 
1241 /*
1242  * Move a page back to the lists.
1243  *
1244  * Must be called with the slab lock held.
1245  *
1246  * On exit the slab lock will have been dropped.
1247  */
1248 static void putback_slab(struct kmem_cache *s, struct page *page)
1249 {
1250 	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
1251 
1252 	if (page->inuse) {
1253 
1254 		if (page->freelist)
1255 			add_partial(n, page);
1256 		else if (SlabDebug(page) && (s->flags & SLAB_STORE_USER))
1257 			add_full(n, page);
1258 		slab_unlock(page);
1259 
1260 	} else {
1261 		if (n->nr_partial < MIN_PARTIAL) {
1262 			/*
1263 			 * Adding an empty slab to the partial slabs in order
1264 			 * to avoid page allocator overhead. This slab needs
1265 			 * to come after the other slabs with objects in
1266 			 * order to fill them up. That way the size of the
1267 			 * partial list stays small. kmem_cache_shrink can
1268 			 * reclaim empty slabs from the partial list.
1269 			 */
1270 			add_partial_tail(n, page);
1271 			slab_unlock(page);
1272 		} else {
1273 			slab_unlock(page);
1274 			discard_slab(s, page);
1275 		}
1276 	}
1277 }
1278 
1279 /*
1280  * Remove the cpu slab
1281  */
1282 static void deactivate_slab(struct kmem_cache *s, struct page *page, int cpu)
1283 {
1284 	/*
1285 	 * Merge cpu freelist into freelist. Typically we get here
1286 	 * because both freelists are empty. So this is unlikely
1287 	 * to occur.
1288 	 */
1289 	while (unlikely(page->lockless_freelist)) {
1290 		void **object;
1291 
1292 		/* Retrieve object from cpu_freelist */
1293 		object = page->lockless_freelist;
1294 		page->lockless_freelist = page->lockless_freelist[page->offset];
1295 
1296 		/* And put onto the regular freelist */
1297 		object[page->offset] = page->freelist;
1298 		page->freelist = object;
1299 		page->inuse--;
1300 	}
1301 	s->cpu_slab[cpu] = NULL;
1302 	ClearPageActive(page);
1303 
1304 	putback_slab(s, page);
1305 }
1306 
1307 static void flush_slab(struct kmem_cache *s, struct page *page, int cpu)
1308 {
1309 	slab_lock(page);
1310 	deactivate_slab(s, page, cpu);
1311 }
1312 
1313 /*
1314  * Flush cpu slab.
1315  * Called from IPI handler with interrupts disabled.
1316  */
1317 static void __flush_cpu_slab(struct kmem_cache *s, int cpu)
1318 {
1319 	struct page *page = s->cpu_slab[cpu];
1320 
1321 	if (likely(page))
1322 		flush_slab(s, page, cpu);
1323 }
1324 
1325 static void flush_cpu_slab(void *d)
1326 {
1327 	struct kmem_cache *s = d;
1328 	int cpu = smp_processor_id();
1329 
1330 	__flush_cpu_slab(s, cpu);
1331 }
1332 
1333 static void flush_all(struct kmem_cache *s)
1334 {
1335 #ifdef CONFIG_SMP
1336 	on_each_cpu(flush_cpu_slab, s, 1, 1);
1337 #else
1338 	unsigned long flags;
1339 
1340 	local_irq_save(flags);
1341 	flush_cpu_slab(s);
1342 	local_irq_restore(flags);
1343 #endif
1344 }
1345 
1346 /*
1347  * Slow path. The lockless freelist is empty or we need to perform
1348  * debugging duties.
1349  *
1350  * Interrupts are disabled.
1351  *
1352  * Processing is still very fast if new objects have been freed to the
1353  * regular freelist. In that case we simply take over the regular freelist
1354  * as the lockless freelist and zap the regular freelist.
1355  *
1356  * If that is not working then we fall back to the partial lists. We take the
1357  * first element of the freelist as the object to allocate now and move the
1358  * rest of the freelist to the lockless freelist.
1359  *
1360  * And if we were unable to get a new slab from the partial slab lists then
1361  * we need to allocate a new slab. This is slowest path since we may sleep.
1362  */
1363 static void *__slab_alloc(struct kmem_cache *s,
1364 		gfp_t gfpflags, int node, void *addr, struct page *page)
1365 {
1366 	void **object;
1367 	int cpu = smp_processor_id();
1368 
1369 	if (!page)
1370 		goto new_slab;
1371 
1372 	slab_lock(page);
1373 	if (unlikely(node != -1 && page_to_nid(page) != node))
1374 		goto another_slab;
1375 load_freelist:
1376 	object = page->freelist;
1377 	if (unlikely(!object))
1378 		goto another_slab;
1379 	if (unlikely(SlabDebug(page)))
1380 		goto debug;
1381 
1382 	object = page->freelist;
1383 	page->lockless_freelist = object[page->offset];
1384 	page->inuse = s->objects;
1385 	page->freelist = NULL;
1386 	slab_unlock(page);
1387 	return object;
1388 
1389 another_slab:
1390 	deactivate_slab(s, page, cpu);
1391 
1392 new_slab:
1393 	page = get_partial(s, gfpflags, node);
1394 	if (page) {
1395 have_slab:
1396 		s->cpu_slab[cpu] = page;
1397 		SetPageActive(page);
1398 		goto load_freelist;
1399 	}
1400 
1401 	page = new_slab(s, gfpflags, node);
1402 	if (page) {
1403 		cpu = smp_processor_id();
1404 		if (s->cpu_slab[cpu]) {
1405 			/*
1406 			 * Someone else populated the cpu_slab while we
1407 			 * enabled interrupts, or we have gotten scheduled
1408 			 * on another cpu. The page may not be on the
1409 			 * requested node even if __GFP_THISNODE was
1410 			 * specified. So we need to recheck.
1411 			 */
1412 			if (node == -1 ||
1413 				page_to_nid(s->cpu_slab[cpu]) == node) {
1414 				/*
1415 				 * Current cpuslab is acceptable and we
1416 				 * want the current one since its cache hot
1417 				 */
1418 				discard_slab(s, page);
1419 				page = s->cpu_slab[cpu];
1420 				slab_lock(page);
1421 				goto load_freelist;
1422 			}
1423 			/* New slab does not fit our expectations */
1424 			flush_slab(s, s->cpu_slab[cpu], cpu);
1425 		}
1426 		slab_lock(page);
1427 		goto have_slab;
1428 	}
1429 	return NULL;
1430 debug:
1431 	object = page->freelist;
1432 	if (!alloc_object_checks(s, page, object))
1433 		goto another_slab;
1434 	if (s->flags & SLAB_STORE_USER)
1435 		set_track(s, object, TRACK_ALLOC, addr);
1436 	trace(s, page, object, 1);
1437 	init_object(s, object, 1);
1438 
1439 	page->inuse++;
1440 	page->freelist = object[page->offset];
1441 	slab_unlock(page);
1442 	return object;
1443 }
1444 
1445 /*
1446  * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
1447  * have the fastpath folded into their functions. So no function call
1448  * overhead for requests that can be satisfied on the fastpath.
1449  *
1450  * The fastpath works by first checking if the lockless freelist can be used.
1451  * If not then __slab_alloc is called for slow processing.
1452  *
1453  * Otherwise we can simply pick the next object from the lockless free list.
1454  */
1455 static void __always_inline *slab_alloc(struct kmem_cache *s,
1456 				gfp_t gfpflags, int node, void *addr)
1457 {
1458 	struct page *page;
1459 	void **object;
1460 	unsigned long flags;
1461 
1462 	local_irq_save(flags);
1463 	page = s->cpu_slab[smp_processor_id()];
1464 	if (unlikely(!page || !page->lockless_freelist ||
1465 			(node != -1 && page_to_nid(page) != node)))
1466 
1467 		object = __slab_alloc(s, gfpflags, node, addr, page);
1468 
1469 	else {
1470 		object = page->lockless_freelist;
1471 		page->lockless_freelist = object[page->offset];
1472 	}
1473 	local_irq_restore(flags);
1474 	return object;
1475 }
1476 
1477 void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
1478 {
1479 	return slab_alloc(s, gfpflags, -1, __builtin_return_address(0));
1480 }
1481 EXPORT_SYMBOL(kmem_cache_alloc);
1482 
1483 #ifdef CONFIG_NUMA
1484 void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
1485 {
1486 	return slab_alloc(s, gfpflags, node, __builtin_return_address(0));
1487 }
1488 EXPORT_SYMBOL(kmem_cache_alloc_node);
1489 #endif
1490 
1491 /*
1492  * Slow patch handling. This may still be called frequently since objects
1493  * have a longer lifetime than the cpu slabs in most processing loads.
1494  *
1495  * So we still attempt to reduce cache line usage. Just take the slab
1496  * lock and free the item. If there is no additional partial page
1497  * handling required then we can return immediately.
1498  */
1499 static void __slab_free(struct kmem_cache *s, struct page *page,
1500 					void *x, void *addr)
1501 {
1502 	void *prior;
1503 	void **object = (void *)x;
1504 
1505 	slab_lock(page);
1506 
1507 	if (unlikely(SlabDebug(page)))
1508 		goto debug;
1509 checks_ok:
1510 	prior = object[page->offset] = page->freelist;
1511 	page->freelist = object;
1512 	page->inuse--;
1513 
1514 	if (unlikely(PageActive(page)))
1515 		/*
1516 		 * Cpu slabs are never on partial lists and are
1517 		 * never freed.
1518 		 */
1519 		goto out_unlock;
1520 
1521 	if (unlikely(!page->inuse))
1522 		goto slab_empty;
1523 
1524 	/*
1525 	 * Objects left in the slab. If it
1526 	 * was not on the partial list before
1527 	 * then add it.
1528 	 */
1529 	if (unlikely(!prior))
1530 		add_partial(get_node(s, page_to_nid(page)), page);
1531 
1532 out_unlock:
1533 	slab_unlock(page);
1534 	return;
1535 
1536 slab_empty:
1537 	if (prior)
1538 		/*
1539 		 * Slab still on the partial list.
1540 		 */
1541 		remove_partial(s, page);
1542 
1543 	slab_unlock(page);
1544 	discard_slab(s, page);
1545 	return;
1546 
1547 debug:
1548 	if (!free_object_checks(s, page, x))
1549 		goto out_unlock;
1550 	if (!PageActive(page) && !page->freelist)
1551 		remove_full(s, page);
1552 	if (s->flags & SLAB_STORE_USER)
1553 		set_track(s, x, TRACK_FREE, addr);
1554 	trace(s, page, object, 0);
1555 	init_object(s, object, 0);
1556 	goto checks_ok;
1557 }
1558 
1559 /*
1560  * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
1561  * can perform fastpath freeing without additional function calls.
1562  *
1563  * The fastpath is only possible if we are freeing to the current cpu slab
1564  * of this processor. This typically the case if we have just allocated
1565  * the item before.
1566  *
1567  * If fastpath is not possible then fall back to __slab_free where we deal
1568  * with all sorts of special processing.
1569  */
1570 static void __always_inline slab_free(struct kmem_cache *s,
1571 			struct page *page, void *x, void *addr)
1572 {
1573 	void **object = (void *)x;
1574 	unsigned long flags;
1575 
1576 	local_irq_save(flags);
1577 	if (likely(page == s->cpu_slab[smp_processor_id()] &&
1578 						!SlabDebug(page))) {
1579 		object[page->offset] = page->lockless_freelist;
1580 		page->lockless_freelist = object;
1581 	} else
1582 		__slab_free(s, page, x, addr);
1583 
1584 	local_irq_restore(flags);
1585 }
1586 
1587 void kmem_cache_free(struct kmem_cache *s, void *x)
1588 {
1589 	struct page *page;
1590 
1591 	page = virt_to_head_page(x);
1592 
1593 	slab_free(s, page, x, __builtin_return_address(0));
1594 }
1595 EXPORT_SYMBOL(kmem_cache_free);
1596 
1597 /* Figure out on which slab object the object resides */
1598 static struct page *get_object_page(const void *x)
1599 {
1600 	struct page *page = virt_to_head_page(x);
1601 
1602 	if (!PageSlab(page))
1603 		return NULL;
1604 
1605 	return page;
1606 }
1607 
1608 /*
1609  * Object placement in a slab is made very easy because we always start at
1610  * offset 0. If we tune the size of the object to the alignment then we can
1611  * get the required alignment by putting one properly sized object after
1612  * another.
1613  *
1614  * Notice that the allocation order determines the sizes of the per cpu
1615  * caches. Each processor has always one slab available for allocations.
1616  * Increasing the allocation order reduces the number of times that slabs
1617  * must be moved on and off the partial lists and is therefore a factor in
1618  * locking overhead.
1619  */
1620 
1621 /*
1622  * Mininum / Maximum order of slab pages. This influences locking overhead
1623  * and slab fragmentation. A higher order reduces the number of partial slabs
1624  * and increases the number of allocations possible without having to
1625  * take the list_lock.
1626  */
1627 static int slub_min_order;
1628 static int slub_max_order = DEFAULT_MAX_ORDER;
1629 static int slub_min_objects = DEFAULT_MIN_OBJECTS;
1630 
1631 /*
1632  * Merge control. If this is set then no merging of slab caches will occur.
1633  * (Could be removed. This was introduced to pacify the merge skeptics.)
1634  */
1635 static int slub_nomerge;
1636 
1637 /*
1638  * Calculate the order of allocation given an slab object size.
1639  *
1640  * The order of allocation has significant impact on performance and other
1641  * system components. Generally order 0 allocations should be preferred since
1642  * order 0 does not cause fragmentation in the page allocator. Larger objects
1643  * be problematic to put into order 0 slabs because there may be too much
1644  * unused space left. We go to a higher order if more than 1/8th of the slab
1645  * would be wasted.
1646  *
1647  * In order to reach satisfactory performance we must ensure that a minimum
1648  * number of objects is in one slab. Otherwise we may generate too much
1649  * activity on the partial lists which requires taking the list_lock. This is
1650  * less a concern for large slabs though which are rarely used.
1651  *
1652  * slub_max_order specifies the order where we begin to stop considering the
1653  * number of objects in a slab as critical. If we reach slub_max_order then
1654  * we try to keep the page order as low as possible. So we accept more waste
1655  * of space in favor of a small page order.
1656  *
1657  * Higher order allocations also allow the placement of more objects in a
1658  * slab and thereby reduce object handling overhead. If the user has
1659  * requested a higher mininum order then we start with that one instead of
1660  * the smallest order which will fit the object.
1661  */
1662 static inline int slab_order(int size, int min_objects,
1663 				int max_order, int fract_leftover)
1664 {
1665 	int order;
1666 	int rem;
1667 
1668 	for (order = max(slub_min_order,
1669 				fls(min_objects * size - 1) - PAGE_SHIFT);
1670 			order <= max_order; order++) {
1671 
1672 		unsigned long slab_size = PAGE_SIZE << order;
1673 
1674 		if (slab_size < min_objects * size)
1675 			continue;
1676 
1677 		rem = slab_size % size;
1678 
1679 		if (rem <= slab_size / fract_leftover)
1680 			break;
1681 
1682 	}
1683 
1684 	return order;
1685 }
1686 
1687 static inline int calculate_order(int size)
1688 {
1689 	int order;
1690 	int min_objects;
1691 	int fraction;
1692 
1693 	/*
1694 	 * Attempt to find best configuration for a slab. This
1695 	 * works by first attempting to generate a layout with
1696 	 * the best configuration and backing off gradually.
1697 	 *
1698 	 * First we reduce the acceptable waste in a slab. Then
1699 	 * we reduce the minimum objects required in a slab.
1700 	 */
1701 	min_objects = slub_min_objects;
1702 	while (min_objects > 1) {
1703 		fraction = 8;
1704 		while (fraction >= 4) {
1705 			order = slab_order(size, min_objects,
1706 						slub_max_order, fraction);
1707 			if (order <= slub_max_order)
1708 				return order;
1709 			fraction /= 2;
1710 		}
1711 		min_objects /= 2;
1712 	}
1713 
1714 	/*
1715 	 * We were unable to place multiple objects in a slab. Now
1716 	 * lets see if we can place a single object there.
1717 	 */
1718 	order = slab_order(size, 1, slub_max_order, 1);
1719 	if (order <= slub_max_order)
1720 		return order;
1721 
1722 	/*
1723 	 * Doh this slab cannot be placed using slub_max_order.
1724 	 */
1725 	order = slab_order(size, 1, MAX_ORDER, 1);
1726 	if (order <= MAX_ORDER)
1727 		return order;
1728 	return -ENOSYS;
1729 }
1730 
1731 /*
1732  * Figure out what the alignment of the objects will be.
1733  */
1734 static unsigned long calculate_alignment(unsigned long flags,
1735 		unsigned long align, unsigned long size)
1736 {
1737 	/*
1738 	 * If the user wants hardware cache aligned objects then
1739 	 * follow that suggestion if the object is sufficiently
1740 	 * large.
1741 	 *
1742 	 * The hardware cache alignment cannot override the
1743 	 * specified alignment though. If that is greater
1744 	 * then use it.
1745 	 */
1746 	if ((flags & SLAB_HWCACHE_ALIGN) &&
1747 			size > cache_line_size() / 2)
1748 		return max_t(unsigned long, align, cache_line_size());
1749 
1750 	if (align < ARCH_SLAB_MINALIGN)
1751 		return ARCH_SLAB_MINALIGN;
1752 
1753 	return ALIGN(align, sizeof(void *));
1754 }
1755 
1756 static void init_kmem_cache_node(struct kmem_cache_node *n)
1757 {
1758 	n->nr_partial = 0;
1759 	atomic_long_set(&n->nr_slabs, 0);
1760 	spin_lock_init(&n->list_lock);
1761 	INIT_LIST_HEAD(&n->partial);
1762 	INIT_LIST_HEAD(&n->full);
1763 }
1764 
1765 #ifdef CONFIG_NUMA
1766 /*
1767  * No kmalloc_node yet so do it by hand. We know that this is the first
1768  * slab on the node for this slabcache. There are no concurrent accesses
1769  * possible.
1770  *
1771  * Note that this function only works on the kmalloc_node_cache
1772  * when allocating for the kmalloc_node_cache.
1773  */
1774 static struct kmem_cache_node * __init early_kmem_cache_node_alloc(gfp_t gfpflags,
1775 								int node)
1776 {
1777 	struct page *page;
1778 	struct kmem_cache_node *n;
1779 
1780 	BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
1781 
1782 	page = new_slab(kmalloc_caches, gfpflags | GFP_THISNODE, node);
1783 	/* new_slab() disables interupts */
1784 	local_irq_enable();
1785 
1786 	BUG_ON(!page);
1787 	n = page->freelist;
1788 	BUG_ON(!n);
1789 	page->freelist = get_freepointer(kmalloc_caches, n);
1790 	page->inuse++;
1791 	kmalloc_caches->node[node] = n;
1792 	init_object(kmalloc_caches, n, 1);
1793 	init_kmem_cache_node(n);
1794 	atomic_long_inc(&n->nr_slabs);
1795 	add_partial(n, page);
1796 	return n;
1797 }
1798 
1799 static void free_kmem_cache_nodes(struct kmem_cache *s)
1800 {
1801 	int node;
1802 
1803 	for_each_online_node(node) {
1804 		struct kmem_cache_node *n = s->node[node];
1805 		if (n && n != &s->local_node)
1806 			kmem_cache_free(kmalloc_caches, n);
1807 		s->node[node] = NULL;
1808 	}
1809 }
1810 
1811 static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
1812 {
1813 	int node;
1814 	int local_node;
1815 
1816 	if (slab_state >= UP)
1817 		local_node = page_to_nid(virt_to_page(s));
1818 	else
1819 		local_node = 0;
1820 
1821 	for_each_online_node(node) {
1822 		struct kmem_cache_node *n;
1823 
1824 		if (local_node == node)
1825 			n = &s->local_node;
1826 		else {
1827 			if (slab_state == DOWN) {
1828 				n = early_kmem_cache_node_alloc(gfpflags,
1829 								node);
1830 				continue;
1831 			}
1832 			n = kmem_cache_alloc_node(kmalloc_caches,
1833 							gfpflags, node);
1834 
1835 			if (!n) {
1836 				free_kmem_cache_nodes(s);
1837 				return 0;
1838 			}
1839 
1840 		}
1841 		s->node[node] = n;
1842 		init_kmem_cache_node(n);
1843 	}
1844 	return 1;
1845 }
1846 #else
1847 static void free_kmem_cache_nodes(struct kmem_cache *s)
1848 {
1849 }
1850 
1851 static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
1852 {
1853 	init_kmem_cache_node(&s->local_node);
1854 	return 1;
1855 }
1856 #endif
1857 
1858 /*
1859  * calculate_sizes() determines the order and the distribution of data within
1860  * a slab object.
1861  */
1862 static int calculate_sizes(struct kmem_cache *s)
1863 {
1864 	unsigned long flags = s->flags;
1865 	unsigned long size = s->objsize;
1866 	unsigned long align = s->align;
1867 
1868 	/*
1869 	 * Determine if we can poison the object itself. If the user of
1870 	 * the slab may touch the object after free or before allocation
1871 	 * then we should never poison the object itself.
1872 	 */
1873 	if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
1874 			!s->ctor && !s->dtor)
1875 		s->flags |= __OBJECT_POISON;
1876 	else
1877 		s->flags &= ~__OBJECT_POISON;
1878 
1879 	/*
1880 	 * Round up object size to the next word boundary. We can only
1881 	 * place the free pointer at word boundaries and this determines
1882 	 * the possible location of the free pointer.
1883 	 */
1884 	size = ALIGN(size, sizeof(void *));
1885 
1886 #ifdef CONFIG_SLUB_DEBUG
1887 	/*
1888 	 * If we are Redzoning then check if there is some space between the
1889 	 * end of the object and the free pointer. If not then add an
1890 	 * additional word to have some bytes to store Redzone information.
1891 	 */
1892 	if ((flags & SLAB_RED_ZONE) && size == s->objsize)
1893 		size += sizeof(void *);
1894 #endif
1895 
1896 	/*
1897 	 * With that we have determined the number of bytes in actual use
1898 	 * by the object. This is the potential offset to the free pointer.
1899 	 */
1900 	s->inuse = size;
1901 
1902 #ifdef CONFIG_SLUB_DEBUG
1903 	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
1904 		s->ctor || s->dtor)) {
1905 		/*
1906 		 * Relocate free pointer after the object if it is not
1907 		 * permitted to overwrite the first word of the object on
1908 		 * kmem_cache_free.
1909 		 *
1910 		 * This is the case if we do RCU, have a constructor or
1911 		 * destructor or are poisoning the objects.
1912 		 */
1913 		s->offset = size;
1914 		size += sizeof(void *);
1915 	}
1916 
1917 	if (flags & SLAB_STORE_USER)
1918 		/*
1919 		 * Need to store information about allocs and frees after
1920 		 * the object.
1921 		 */
1922 		size += 2 * sizeof(struct track);
1923 
1924 	if (flags & SLAB_RED_ZONE)
1925 		/*
1926 		 * Add some empty padding so that we can catch
1927 		 * overwrites from earlier objects rather than let
1928 		 * tracking information or the free pointer be
1929 		 * corrupted if an user writes before the start
1930 		 * of the object.
1931 		 */
1932 		size += sizeof(void *);
1933 #endif
1934 
1935 	/*
1936 	 * Determine the alignment based on various parameters that the
1937 	 * user specified and the dynamic determination of cache line size
1938 	 * on bootup.
1939 	 */
1940 	align = calculate_alignment(flags, align, s->objsize);
1941 
1942 	/*
1943 	 * SLUB stores one object immediately after another beginning from
1944 	 * offset 0. In order to align the objects we have to simply size
1945 	 * each object to conform to the alignment.
1946 	 */
1947 	size = ALIGN(size, align);
1948 	s->size = size;
1949 
1950 	s->order = calculate_order(size);
1951 	if (s->order < 0)
1952 		return 0;
1953 
1954 	/*
1955 	 * Determine the number of objects per slab
1956 	 */
1957 	s->objects = (PAGE_SIZE << s->order) / size;
1958 
1959 	/*
1960 	 * Verify that the number of objects is within permitted limits.
1961 	 * The page->inuse field is only 16 bit wide! So we cannot have
1962 	 * more than 64k objects per slab.
1963 	 */
1964 	if (!s->objects || s->objects > 65535)
1965 		return 0;
1966 	return 1;
1967 
1968 }
1969 
1970 static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
1971 		const char *name, size_t size,
1972 		size_t align, unsigned long flags,
1973 		void (*ctor)(void *, struct kmem_cache *, unsigned long),
1974 		void (*dtor)(void *, struct kmem_cache *, unsigned long))
1975 {
1976 	memset(s, 0, kmem_size);
1977 	s->name = name;
1978 	s->ctor = ctor;
1979 	s->dtor = dtor;
1980 	s->objsize = size;
1981 	s->flags = flags;
1982 	s->align = align;
1983 	kmem_cache_open_debug_check(s);
1984 
1985 	if (!calculate_sizes(s))
1986 		goto error;
1987 
1988 	s->refcount = 1;
1989 #ifdef CONFIG_NUMA
1990 	s->defrag_ratio = 100;
1991 #endif
1992 
1993 	if (init_kmem_cache_nodes(s, gfpflags & ~SLUB_DMA))
1994 		return 1;
1995 error:
1996 	if (flags & SLAB_PANIC)
1997 		panic("Cannot create slab %s size=%lu realsize=%u "
1998 			"order=%u offset=%u flags=%lx\n",
1999 			s->name, (unsigned long)size, s->size, s->order,
2000 			s->offset, flags);
2001 	return 0;
2002 }
2003 EXPORT_SYMBOL(kmem_cache_open);
2004 
2005 /*
2006  * Check if a given pointer is valid
2007  */
2008 int kmem_ptr_validate(struct kmem_cache *s, const void *object)
2009 {
2010 	struct page * page;
2011 
2012 	page = get_object_page(object);
2013 
2014 	if (!page || s != page->slab)
2015 		/* No slab or wrong slab */
2016 		return 0;
2017 
2018 	if (!check_valid_pointer(s, page, object))
2019 		return 0;
2020 
2021 	/*
2022 	 * We could also check if the object is on the slabs freelist.
2023 	 * But this would be too expensive and it seems that the main
2024 	 * purpose of kmem_ptr_valid is to check if the object belongs
2025 	 * to a certain slab.
2026 	 */
2027 	return 1;
2028 }
2029 EXPORT_SYMBOL(kmem_ptr_validate);
2030 
2031 /*
2032  * Determine the size of a slab object
2033  */
2034 unsigned int kmem_cache_size(struct kmem_cache *s)
2035 {
2036 	return s->objsize;
2037 }
2038 EXPORT_SYMBOL(kmem_cache_size);
2039 
2040 const char *kmem_cache_name(struct kmem_cache *s)
2041 {
2042 	return s->name;
2043 }
2044 EXPORT_SYMBOL(kmem_cache_name);
2045 
2046 /*
2047  * Attempt to free all slabs on a node. Return the number of slabs we
2048  * were unable to free.
2049  */
2050 static int free_list(struct kmem_cache *s, struct kmem_cache_node *n,
2051 			struct list_head *list)
2052 {
2053 	int slabs_inuse = 0;
2054 	unsigned long flags;
2055 	struct page *page, *h;
2056 
2057 	spin_lock_irqsave(&n->list_lock, flags);
2058 	list_for_each_entry_safe(page, h, list, lru)
2059 		if (!page->inuse) {
2060 			list_del(&page->lru);
2061 			discard_slab(s, page);
2062 		} else
2063 			slabs_inuse++;
2064 	spin_unlock_irqrestore(&n->list_lock, flags);
2065 	return slabs_inuse;
2066 }
2067 
2068 /*
2069  * Release all resources used by a slab cache.
2070  */
2071 static int kmem_cache_close(struct kmem_cache *s)
2072 {
2073 	int node;
2074 
2075 	flush_all(s);
2076 
2077 	/* Attempt to free all objects */
2078 	for_each_online_node(node) {
2079 		struct kmem_cache_node *n = get_node(s, node);
2080 
2081 		n->nr_partial -= free_list(s, n, &n->partial);
2082 		if (atomic_long_read(&n->nr_slabs))
2083 			return 1;
2084 	}
2085 	free_kmem_cache_nodes(s);
2086 	return 0;
2087 }
2088 
2089 /*
2090  * Close a cache and release the kmem_cache structure
2091  * (must be used for caches created using kmem_cache_create)
2092  */
2093 void kmem_cache_destroy(struct kmem_cache *s)
2094 {
2095 	down_write(&slub_lock);
2096 	s->refcount--;
2097 	if (!s->refcount) {
2098 		list_del(&s->list);
2099 		if (kmem_cache_close(s))
2100 			WARN_ON(1);
2101 		sysfs_slab_remove(s);
2102 		kfree(s);
2103 	}
2104 	up_write(&slub_lock);
2105 }
2106 EXPORT_SYMBOL(kmem_cache_destroy);
2107 
2108 /********************************************************************
2109  *		Kmalloc subsystem
2110  *******************************************************************/
2111 
2112 struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1] __cacheline_aligned;
2113 EXPORT_SYMBOL(kmalloc_caches);
2114 
2115 #ifdef CONFIG_ZONE_DMA
2116 static struct kmem_cache *kmalloc_caches_dma[KMALLOC_SHIFT_HIGH + 1];
2117 #endif
2118 
2119 static int __init setup_slub_min_order(char *str)
2120 {
2121 	get_option (&str, &slub_min_order);
2122 
2123 	return 1;
2124 }
2125 
2126 __setup("slub_min_order=", setup_slub_min_order);
2127 
2128 static int __init setup_slub_max_order(char *str)
2129 {
2130 	get_option (&str, &slub_max_order);
2131 
2132 	return 1;
2133 }
2134 
2135 __setup("slub_max_order=", setup_slub_max_order);
2136 
2137 static int __init setup_slub_min_objects(char *str)
2138 {
2139 	get_option (&str, &slub_min_objects);
2140 
2141 	return 1;
2142 }
2143 
2144 __setup("slub_min_objects=", setup_slub_min_objects);
2145 
2146 static int __init setup_slub_nomerge(char *str)
2147 {
2148 	slub_nomerge = 1;
2149 	return 1;
2150 }
2151 
2152 __setup("slub_nomerge", setup_slub_nomerge);
2153 
2154 static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,
2155 		const char *name, int size, gfp_t gfp_flags)
2156 {
2157 	unsigned int flags = 0;
2158 
2159 	if (gfp_flags & SLUB_DMA)
2160 		flags = SLAB_CACHE_DMA;
2161 
2162 	down_write(&slub_lock);
2163 	if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
2164 			flags, NULL, NULL))
2165 		goto panic;
2166 
2167 	list_add(&s->list, &slab_caches);
2168 	up_write(&slub_lock);
2169 	if (sysfs_slab_add(s))
2170 		goto panic;
2171 	return s;
2172 
2173 panic:
2174 	panic("Creation of kmalloc slab %s size=%d failed.\n", name, size);
2175 }
2176 
2177 static struct kmem_cache *get_slab(size_t size, gfp_t flags)
2178 {
2179 	int index = kmalloc_index(size);
2180 
2181 	if (!index)
2182 		return NULL;
2183 
2184 	/* Allocation too large? */
2185 	BUG_ON(index < 0);
2186 
2187 #ifdef CONFIG_ZONE_DMA
2188 	if ((flags & SLUB_DMA)) {
2189 		struct kmem_cache *s;
2190 		struct kmem_cache *x;
2191 		char *text;
2192 		size_t realsize;
2193 
2194 		s = kmalloc_caches_dma[index];
2195 		if (s)
2196 			return s;
2197 
2198 		/* Dynamically create dma cache */
2199 		x = kmalloc(kmem_size, flags & ~SLUB_DMA);
2200 		if (!x)
2201 			panic("Unable to allocate memory for dma cache\n");
2202 
2203 		if (index <= KMALLOC_SHIFT_HIGH)
2204 			realsize = 1 << index;
2205 		else {
2206 			if (index == 1)
2207 				realsize = 96;
2208 			else
2209 				realsize = 192;
2210 		}
2211 
2212 		text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
2213 				(unsigned int)realsize);
2214 		s = create_kmalloc_cache(x, text, realsize, flags);
2215 		kmalloc_caches_dma[index] = s;
2216 		return s;
2217 	}
2218 #endif
2219 	return &kmalloc_caches[index];
2220 }
2221 
2222 void *__kmalloc(size_t size, gfp_t flags)
2223 {
2224 	struct kmem_cache *s = get_slab(size, flags);
2225 
2226 	if (s)
2227 		return slab_alloc(s, flags, -1, __builtin_return_address(0));
2228 	return NULL;
2229 }
2230 EXPORT_SYMBOL(__kmalloc);
2231 
2232 #ifdef CONFIG_NUMA
2233 void *__kmalloc_node(size_t size, gfp_t flags, int node)
2234 {
2235 	struct kmem_cache *s = get_slab(size, flags);
2236 
2237 	if (s)
2238 		return slab_alloc(s, flags, node, __builtin_return_address(0));
2239 	return NULL;
2240 }
2241 EXPORT_SYMBOL(__kmalloc_node);
2242 #endif
2243 
2244 size_t ksize(const void *object)
2245 {
2246 	struct page *page = get_object_page(object);
2247 	struct kmem_cache *s;
2248 
2249 	BUG_ON(!page);
2250 	s = page->slab;
2251 	BUG_ON(!s);
2252 
2253 	/*
2254 	 * Debugging requires use of the padding between object
2255 	 * and whatever may come after it.
2256 	 */
2257 	if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
2258 		return s->objsize;
2259 
2260 	/*
2261 	 * If we have the need to store the freelist pointer
2262 	 * back there or track user information then we can
2263 	 * only use the space before that information.
2264 	 */
2265 	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
2266 		return s->inuse;
2267 
2268 	/*
2269 	 * Else we can use all the padding etc for the allocation
2270 	 */
2271 	return s->size;
2272 }
2273 EXPORT_SYMBOL(ksize);
2274 
2275 void kfree(const void *x)
2276 {
2277 	struct kmem_cache *s;
2278 	struct page *page;
2279 
2280 	if (!x)
2281 		return;
2282 
2283 	page = virt_to_head_page(x);
2284 	s = page->slab;
2285 
2286 	slab_free(s, page, (void *)x, __builtin_return_address(0));
2287 }
2288 EXPORT_SYMBOL(kfree);
2289 
2290 /*
2291  * kmem_cache_shrink removes empty slabs from the partial lists and sorts
2292  * the remaining slabs by the number of items in use. The slabs with the
2293  * most items in use come first. New allocations will then fill those up
2294  * and thus they can be removed from the partial lists.
2295  *
2296  * The slabs with the least items are placed last. This results in them
2297  * being allocated from last increasing the chance that the last objects
2298  * are freed in them.
2299  */
2300 int kmem_cache_shrink(struct kmem_cache *s)
2301 {
2302 	int node;
2303 	int i;
2304 	struct kmem_cache_node *n;
2305 	struct page *page;
2306 	struct page *t;
2307 	struct list_head *slabs_by_inuse =
2308 		kmalloc(sizeof(struct list_head) * s->objects, GFP_KERNEL);
2309 	unsigned long flags;
2310 
2311 	if (!slabs_by_inuse)
2312 		return -ENOMEM;
2313 
2314 	flush_all(s);
2315 	for_each_online_node(node) {
2316 		n = get_node(s, node);
2317 
2318 		if (!n->nr_partial)
2319 			continue;
2320 
2321 		for (i = 0; i < s->objects; i++)
2322 			INIT_LIST_HEAD(slabs_by_inuse + i);
2323 
2324 		spin_lock_irqsave(&n->list_lock, flags);
2325 
2326 		/*
2327 		 * Build lists indexed by the items in use in each slab.
2328 		 *
2329 		 * Note that concurrent frees may occur while we hold the
2330 		 * list_lock. page->inuse here is the upper limit.
2331 		 */
2332 		list_for_each_entry_safe(page, t, &n->partial, lru) {
2333 			if (!page->inuse && slab_trylock(page)) {
2334 				/*
2335 				 * Must hold slab lock here because slab_free
2336 				 * may have freed the last object and be
2337 				 * waiting to release the slab.
2338 				 */
2339 				list_del(&page->lru);
2340 				n->nr_partial--;
2341 				slab_unlock(page);
2342 				discard_slab(s, page);
2343 			} else {
2344 				if (n->nr_partial > MAX_PARTIAL)
2345 					list_move(&page->lru,
2346 					slabs_by_inuse + page->inuse);
2347 			}
2348 		}
2349 
2350 		if (n->nr_partial <= MAX_PARTIAL)
2351 			goto out;
2352 
2353 		/*
2354 		 * Rebuild the partial list with the slabs filled up most
2355 		 * first and the least used slabs at the end.
2356 		 */
2357 		for (i = s->objects - 1; i >= 0; i--)
2358 			list_splice(slabs_by_inuse + i, n->partial.prev);
2359 
2360 	out:
2361 		spin_unlock_irqrestore(&n->list_lock, flags);
2362 	}
2363 
2364 	kfree(slabs_by_inuse);
2365 	return 0;
2366 }
2367 EXPORT_SYMBOL(kmem_cache_shrink);
2368 
2369 /**
2370  * krealloc - reallocate memory. The contents will remain unchanged.
2371  * @p: object to reallocate memory for.
2372  * @new_size: how many bytes of memory are required.
2373  * @flags: the type of memory to allocate.
2374  *
2375  * The contents of the object pointed to are preserved up to the
2376  * lesser of the new and old sizes.  If @p is %NULL, krealloc()
2377  * behaves exactly like kmalloc().  If @size is 0 and @p is not a
2378  * %NULL pointer, the object pointed to is freed.
2379  */
2380 void *krealloc(const void *p, size_t new_size, gfp_t flags)
2381 {
2382 	void *ret;
2383 	size_t ks;
2384 
2385 	if (unlikely(!p))
2386 		return kmalloc(new_size, flags);
2387 
2388 	if (unlikely(!new_size)) {
2389 		kfree(p);
2390 		return NULL;
2391 	}
2392 
2393 	ks = ksize(p);
2394 	if (ks >= new_size)
2395 		return (void *)p;
2396 
2397 	ret = kmalloc(new_size, flags);
2398 	if (ret) {
2399 		memcpy(ret, p, min(new_size, ks));
2400 		kfree(p);
2401 	}
2402 	return ret;
2403 }
2404 EXPORT_SYMBOL(krealloc);
2405 
2406 /********************************************************************
2407  *			Basic setup of slabs
2408  *******************************************************************/
2409 
2410 void __init kmem_cache_init(void)
2411 {
2412 	int i;
2413 
2414 #ifdef CONFIG_NUMA
2415 	/*
2416 	 * Must first have the slab cache available for the allocations of the
2417 	 * struct kmem_cache_node's. There is special bootstrap code in
2418 	 * kmem_cache_open for slab_state == DOWN.
2419 	 */
2420 	create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
2421 		sizeof(struct kmem_cache_node), GFP_KERNEL);
2422 #endif
2423 
2424 	/* Able to allocate the per node structures */
2425 	slab_state = PARTIAL;
2426 
2427 	/* Caches that are not of the two-to-the-power-of size */
2428 	create_kmalloc_cache(&kmalloc_caches[1],
2429 				"kmalloc-96", 96, GFP_KERNEL);
2430 	create_kmalloc_cache(&kmalloc_caches[2],
2431 				"kmalloc-192", 192, GFP_KERNEL);
2432 
2433 	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
2434 		create_kmalloc_cache(&kmalloc_caches[i],
2435 			"kmalloc", 1 << i, GFP_KERNEL);
2436 
2437 	slab_state = UP;
2438 
2439 	/* Provide the correct kmalloc names now that the caches are up */
2440 	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
2441 		kmalloc_caches[i]. name =
2442 			kasprintf(GFP_KERNEL, "kmalloc-%d", 1 << i);
2443 
2444 #ifdef CONFIG_SMP
2445 	register_cpu_notifier(&slab_notifier);
2446 #endif
2447 
2448 	kmem_size = offsetof(struct kmem_cache, cpu_slab) +
2449 				nr_cpu_ids * sizeof(struct page *);
2450 
2451 	printk(KERN_INFO "SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d,"
2452 		" Processors=%d, Nodes=%d\n",
2453 		KMALLOC_SHIFT_HIGH, cache_line_size(),
2454 		slub_min_order, slub_max_order, slub_min_objects,
2455 		nr_cpu_ids, nr_node_ids);
2456 }
2457 
2458 /*
2459  * Find a mergeable slab cache
2460  */
2461 static int slab_unmergeable(struct kmem_cache *s)
2462 {
2463 	if (slub_nomerge || (s->flags & SLUB_NEVER_MERGE))
2464 		return 1;
2465 
2466 	if (s->ctor || s->dtor)
2467 		return 1;
2468 
2469 	return 0;
2470 }
2471 
2472 static struct kmem_cache *find_mergeable(size_t size,
2473 		size_t align, unsigned long flags,
2474 		void (*ctor)(void *, struct kmem_cache *, unsigned long),
2475 		void (*dtor)(void *, struct kmem_cache *, unsigned long))
2476 {
2477 	struct list_head *h;
2478 
2479 	if (slub_nomerge || (flags & SLUB_NEVER_MERGE))
2480 		return NULL;
2481 
2482 	if (ctor || dtor)
2483 		return NULL;
2484 
2485 	size = ALIGN(size, sizeof(void *));
2486 	align = calculate_alignment(flags, align, size);
2487 	size = ALIGN(size, align);
2488 
2489 	list_for_each(h, &slab_caches) {
2490 		struct kmem_cache *s =
2491 			container_of(h, struct kmem_cache, list);
2492 
2493 		if (slab_unmergeable(s))
2494 			continue;
2495 
2496 		if (size > s->size)
2497 			continue;
2498 
2499 		if (((flags | slub_debug) & SLUB_MERGE_SAME) !=
2500 			(s->flags & SLUB_MERGE_SAME))
2501 				continue;
2502 		/*
2503 		 * Check if alignment is compatible.
2504 		 * Courtesy of Adrian Drzewiecki
2505 		 */
2506 		if ((s->size & ~(align -1)) != s->size)
2507 			continue;
2508 
2509 		if (s->size - size >= sizeof(void *))
2510 			continue;
2511 
2512 		return s;
2513 	}
2514 	return NULL;
2515 }
2516 
2517 struct kmem_cache *kmem_cache_create(const char *name, size_t size,
2518 		size_t align, unsigned long flags,
2519 		void (*ctor)(void *, struct kmem_cache *, unsigned long),
2520 		void (*dtor)(void *, struct kmem_cache *, unsigned long))
2521 {
2522 	struct kmem_cache *s;
2523 
2524 	down_write(&slub_lock);
2525 	s = find_mergeable(size, align, flags, dtor, ctor);
2526 	if (s) {
2527 		s->refcount++;
2528 		/*
2529 		 * Adjust the object sizes so that we clear
2530 		 * the complete object on kzalloc.
2531 		 */
2532 		s->objsize = max(s->objsize, (int)size);
2533 		s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
2534 		if (sysfs_slab_alias(s, name))
2535 			goto err;
2536 	} else {
2537 		s = kmalloc(kmem_size, GFP_KERNEL);
2538 		if (s && kmem_cache_open(s, GFP_KERNEL, name,
2539 				size, align, flags, ctor, dtor)) {
2540 			if (sysfs_slab_add(s)) {
2541 				kfree(s);
2542 				goto err;
2543 			}
2544 			list_add(&s->list, &slab_caches);
2545 		} else
2546 			kfree(s);
2547 	}
2548 	up_write(&slub_lock);
2549 	return s;
2550 
2551 err:
2552 	up_write(&slub_lock);
2553 	if (flags & SLAB_PANIC)
2554 		panic("Cannot create slabcache %s\n", name);
2555 	else
2556 		s = NULL;
2557 	return s;
2558 }
2559 EXPORT_SYMBOL(kmem_cache_create);
2560 
2561 void *kmem_cache_zalloc(struct kmem_cache *s, gfp_t flags)
2562 {
2563 	void *x;
2564 
2565 	x = slab_alloc(s, flags, -1, __builtin_return_address(0));
2566 	if (x)
2567 		memset(x, 0, s->objsize);
2568 	return x;
2569 }
2570 EXPORT_SYMBOL(kmem_cache_zalloc);
2571 
2572 #ifdef CONFIG_SMP
2573 static void for_all_slabs(void (*func)(struct kmem_cache *, int), int cpu)
2574 {
2575 	struct list_head *h;
2576 
2577 	down_read(&slub_lock);
2578 	list_for_each(h, &slab_caches) {
2579 		struct kmem_cache *s =
2580 			container_of(h, struct kmem_cache, list);
2581 
2582 		func(s, cpu);
2583 	}
2584 	up_read(&slub_lock);
2585 }
2586 
2587 /*
2588  * Use the cpu notifier to insure that the cpu slabs are flushed when
2589  * necessary.
2590  */
2591 static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb,
2592 		unsigned long action, void *hcpu)
2593 {
2594 	long cpu = (long)hcpu;
2595 
2596 	switch (action) {
2597 	case CPU_UP_CANCELED:
2598 	case CPU_UP_CANCELED_FROZEN:
2599 	case CPU_DEAD:
2600 	case CPU_DEAD_FROZEN:
2601 		for_all_slabs(__flush_cpu_slab, cpu);
2602 		break;
2603 	default:
2604 		break;
2605 	}
2606 	return NOTIFY_OK;
2607 }
2608 
2609 static struct notifier_block __cpuinitdata slab_notifier =
2610 	{ &slab_cpuup_callback, NULL, 0 };
2611 
2612 #endif
2613 
2614 void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, void *caller)
2615 {
2616 	struct kmem_cache *s = get_slab(size, gfpflags);
2617 
2618 	if (!s)
2619 		return NULL;
2620 
2621 	return slab_alloc(s, gfpflags, -1, caller);
2622 }
2623 
2624 void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
2625 					int node, void *caller)
2626 {
2627 	struct kmem_cache *s = get_slab(size, gfpflags);
2628 
2629 	if (!s)
2630 		return NULL;
2631 
2632 	return slab_alloc(s, gfpflags, node, caller);
2633 }
2634 
2635 #if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)
2636 static int validate_slab(struct kmem_cache *s, struct page *page)
2637 {
2638 	void *p;
2639 	void *addr = page_address(page);
2640 	DECLARE_BITMAP(map, s->objects);
2641 
2642 	if (!check_slab(s, page) ||
2643 			!on_freelist(s, page, NULL))
2644 		return 0;
2645 
2646 	/* Now we know that a valid freelist exists */
2647 	bitmap_zero(map, s->objects);
2648 
2649 	for_each_free_object(p, s, page->freelist) {
2650 		set_bit(slab_index(p, s, addr), map);
2651 		if (!check_object(s, page, p, 0))
2652 			return 0;
2653 	}
2654 
2655 	for_each_object(p, s, addr)
2656 		if (!test_bit(slab_index(p, s, addr), map))
2657 			if (!check_object(s, page, p, 1))
2658 				return 0;
2659 	return 1;
2660 }
2661 
2662 static void validate_slab_slab(struct kmem_cache *s, struct page *page)
2663 {
2664 	if (slab_trylock(page)) {
2665 		validate_slab(s, page);
2666 		slab_unlock(page);
2667 	} else
2668 		printk(KERN_INFO "SLUB %s: Skipped busy slab 0x%p\n",
2669 			s->name, page);
2670 
2671 	if (s->flags & DEBUG_DEFAULT_FLAGS) {
2672 		if (!SlabDebug(page))
2673 			printk(KERN_ERR "SLUB %s: SlabDebug not set "
2674 				"on slab 0x%p\n", s->name, page);
2675 	} else {
2676 		if (SlabDebug(page))
2677 			printk(KERN_ERR "SLUB %s: SlabDebug set on "
2678 				"slab 0x%p\n", s->name, page);
2679 	}
2680 }
2681 
2682 static int validate_slab_node(struct kmem_cache *s, struct kmem_cache_node *n)
2683 {
2684 	unsigned long count = 0;
2685 	struct page *page;
2686 	unsigned long flags;
2687 
2688 	spin_lock_irqsave(&n->list_lock, flags);
2689 
2690 	list_for_each_entry(page, &n->partial, lru) {
2691 		validate_slab_slab(s, page);
2692 		count++;
2693 	}
2694 	if (count != n->nr_partial)
2695 		printk(KERN_ERR "SLUB %s: %ld partial slabs counted but "
2696 			"counter=%ld\n", s->name, count, n->nr_partial);
2697 
2698 	if (!(s->flags & SLAB_STORE_USER))
2699 		goto out;
2700 
2701 	list_for_each_entry(page, &n->full, lru) {
2702 		validate_slab_slab(s, page);
2703 		count++;
2704 	}
2705 	if (count != atomic_long_read(&n->nr_slabs))
2706 		printk(KERN_ERR "SLUB: %s %ld slabs counted but "
2707 			"counter=%ld\n", s->name, count,
2708 			atomic_long_read(&n->nr_slabs));
2709 
2710 out:
2711 	spin_unlock_irqrestore(&n->list_lock, flags);
2712 	return count;
2713 }
2714 
2715 static unsigned long validate_slab_cache(struct kmem_cache *s)
2716 {
2717 	int node;
2718 	unsigned long count = 0;
2719 
2720 	flush_all(s);
2721 	for_each_online_node(node) {
2722 		struct kmem_cache_node *n = get_node(s, node);
2723 
2724 		count += validate_slab_node(s, n);
2725 	}
2726 	return count;
2727 }
2728 
2729 #ifdef SLUB_RESILIENCY_TEST
2730 static void resiliency_test(void)
2731 {
2732 	u8 *p;
2733 
2734 	printk(KERN_ERR "SLUB resiliency testing\n");
2735 	printk(KERN_ERR "-----------------------\n");
2736 	printk(KERN_ERR "A. Corruption after allocation\n");
2737 
2738 	p = kzalloc(16, GFP_KERNEL);
2739 	p[16] = 0x12;
2740 	printk(KERN_ERR "\n1. kmalloc-16: Clobber Redzone/next pointer"
2741 			" 0x12->0x%p\n\n", p + 16);
2742 
2743 	validate_slab_cache(kmalloc_caches + 4);
2744 
2745 	/* Hmmm... The next two are dangerous */
2746 	p = kzalloc(32, GFP_KERNEL);
2747 	p[32 + sizeof(void *)] = 0x34;
2748 	printk(KERN_ERR "\n2. kmalloc-32: Clobber next pointer/next slab"
2749 		 	" 0x34 -> -0x%p\n", p);
2750 	printk(KERN_ERR "If allocated object is overwritten then not detectable\n\n");
2751 
2752 	validate_slab_cache(kmalloc_caches + 5);
2753 	p = kzalloc(64, GFP_KERNEL);
2754 	p += 64 + (get_cycles() & 0xff) * sizeof(void *);
2755 	*p = 0x56;
2756 	printk(KERN_ERR "\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
2757 									p);
2758 	printk(KERN_ERR "If allocated object is overwritten then not detectable\n\n");
2759 	validate_slab_cache(kmalloc_caches + 6);
2760 
2761 	printk(KERN_ERR "\nB. Corruption after free\n");
2762 	p = kzalloc(128, GFP_KERNEL);
2763 	kfree(p);
2764 	*p = 0x78;
2765 	printk(KERN_ERR "1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
2766 	validate_slab_cache(kmalloc_caches + 7);
2767 
2768 	p = kzalloc(256, GFP_KERNEL);
2769 	kfree(p);
2770 	p[50] = 0x9a;
2771 	printk(KERN_ERR "\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
2772 	validate_slab_cache(kmalloc_caches + 8);
2773 
2774 	p = kzalloc(512, GFP_KERNEL);
2775 	kfree(p);
2776 	p[512] = 0xab;
2777 	printk(KERN_ERR "\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
2778 	validate_slab_cache(kmalloc_caches + 9);
2779 }
2780 #else
2781 static void resiliency_test(void) {};
2782 #endif
2783 
2784 /*
2785  * Generate lists of code addresses where slabcache objects are allocated
2786  * and freed.
2787  */
2788 
2789 struct location {
2790 	unsigned long count;
2791 	void *addr;
2792 	long long sum_time;
2793 	long min_time;
2794 	long max_time;
2795 	long min_pid;
2796 	long max_pid;
2797 	cpumask_t cpus;
2798 	nodemask_t nodes;
2799 };
2800 
2801 struct loc_track {
2802 	unsigned long max;
2803 	unsigned long count;
2804 	struct location *loc;
2805 };
2806 
2807 static void free_loc_track(struct loc_track *t)
2808 {
2809 	if (t->max)
2810 		free_pages((unsigned long)t->loc,
2811 			get_order(sizeof(struct location) * t->max));
2812 }
2813 
2814 static int alloc_loc_track(struct loc_track *t, unsigned long max)
2815 {
2816 	struct location *l;
2817 	int order;
2818 
2819 	if (!max)
2820 		max = PAGE_SIZE / sizeof(struct location);
2821 
2822 	order = get_order(sizeof(struct location) * max);
2823 
2824 	l = (void *)__get_free_pages(GFP_KERNEL, order);
2825 
2826 	if (!l)
2827 		return 0;
2828 
2829 	if (t->count) {
2830 		memcpy(l, t->loc, sizeof(struct location) * t->count);
2831 		free_loc_track(t);
2832 	}
2833 	t->max = max;
2834 	t->loc = l;
2835 	return 1;
2836 }
2837 
2838 static int add_location(struct loc_track *t, struct kmem_cache *s,
2839 				const struct track *track)
2840 {
2841 	long start, end, pos;
2842 	struct location *l;
2843 	void *caddr;
2844 	unsigned long age = jiffies - track->when;
2845 
2846 	start = -1;
2847 	end = t->count;
2848 
2849 	for ( ; ; ) {
2850 		pos = start + (end - start + 1) / 2;
2851 
2852 		/*
2853 		 * There is nothing at "end". If we end up there
2854 		 * we need to add something to before end.
2855 		 */
2856 		if (pos == end)
2857 			break;
2858 
2859 		caddr = t->loc[pos].addr;
2860 		if (track->addr == caddr) {
2861 
2862 			l = &t->loc[pos];
2863 			l->count++;
2864 			if (track->when) {
2865 				l->sum_time += age;
2866 				if (age < l->min_time)
2867 					l->min_time = age;
2868 				if (age > l->max_time)
2869 					l->max_time = age;
2870 
2871 				if (track->pid < l->min_pid)
2872 					l->min_pid = track->pid;
2873 				if (track->pid > l->max_pid)
2874 					l->max_pid = track->pid;
2875 
2876 				cpu_set(track->cpu, l->cpus);
2877 			}
2878 			node_set(page_to_nid(virt_to_page(track)), l->nodes);
2879 			return 1;
2880 		}
2881 
2882 		if (track->addr < caddr)
2883 			end = pos;
2884 		else
2885 			start = pos;
2886 	}
2887 
2888 	/*
2889 	 * Not found. Insert new tracking element.
2890 	 */
2891 	if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max))
2892 		return 0;
2893 
2894 	l = t->loc + pos;
2895 	if (pos < t->count)
2896 		memmove(l + 1, l,
2897 			(t->count - pos) * sizeof(struct location));
2898 	t->count++;
2899 	l->count = 1;
2900 	l->addr = track->addr;
2901 	l->sum_time = age;
2902 	l->min_time = age;
2903 	l->max_time = age;
2904 	l->min_pid = track->pid;
2905 	l->max_pid = track->pid;
2906 	cpus_clear(l->cpus);
2907 	cpu_set(track->cpu, l->cpus);
2908 	nodes_clear(l->nodes);
2909 	node_set(page_to_nid(virt_to_page(track)), l->nodes);
2910 	return 1;
2911 }
2912 
2913 static void process_slab(struct loc_track *t, struct kmem_cache *s,
2914 		struct page *page, enum track_item alloc)
2915 {
2916 	void *addr = page_address(page);
2917 	DECLARE_BITMAP(map, s->objects);
2918 	void *p;
2919 
2920 	bitmap_zero(map, s->objects);
2921 	for_each_free_object(p, s, page->freelist)
2922 		set_bit(slab_index(p, s, addr), map);
2923 
2924 	for_each_object(p, s, addr)
2925 		if (!test_bit(slab_index(p, s, addr), map))
2926 			add_location(t, s, get_track(s, p, alloc));
2927 }
2928 
2929 static int list_locations(struct kmem_cache *s, char *buf,
2930 					enum track_item alloc)
2931 {
2932 	int n = 0;
2933 	unsigned long i;
2934 	struct loc_track t;
2935 	int node;
2936 
2937 	t.count = 0;
2938 	t.max = 0;
2939 
2940 	/* Push back cpu slabs */
2941 	flush_all(s);
2942 
2943 	for_each_online_node(node) {
2944 		struct kmem_cache_node *n = get_node(s, node);
2945 		unsigned long flags;
2946 		struct page *page;
2947 
2948 		if (!atomic_read(&n->nr_slabs))
2949 			continue;
2950 
2951 		spin_lock_irqsave(&n->list_lock, flags);
2952 		list_for_each_entry(page, &n->partial, lru)
2953 			process_slab(&t, s, page, alloc);
2954 		list_for_each_entry(page, &n->full, lru)
2955 			process_slab(&t, s, page, alloc);
2956 		spin_unlock_irqrestore(&n->list_lock, flags);
2957 	}
2958 
2959 	for (i = 0; i < t.count; i++) {
2960 		struct location *l = &t.loc[i];
2961 
2962 		if (n > PAGE_SIZE - 100)
2963 			break;
2964 		n += sprintf(buf + n, "%7ld ", l->count);
2965 
2966 		if (l->addr)
2967 			n += sprint_symbol(buf + n, (unsigned long)l->addr);
2968 		else
2969 			n += sprintf(buf + n, "<not-available>");
2970 
2971 		if (l->sum_time != l->min_time) {
2972 			unsigned long remainder;
2973 
2974 			n += sprintf(buf + n, " age=%ld/%ld/%ld",
2975 			l->min_time,
2976 			div_long_long_rem(l->sum_time, l->count, &remainder),
2977 			l->max_time);
2978 		} else
2979 			n += sprintf(buf + n, " age=%ld",
2980 				l->min_time);
2981 
2982 		if (l->min_pid != l->max_pid)
2983 			n += sprintf(buf + n, " pid=%ld-%ld",
2984 				l->min_pid, l->max_pid);
2985 		else
2986 			n += sprintf(buf + n, " pid=%ld",
2987 				l->min_pid);
2988 
2989 		if (num_online_cpus() > 1 && !cpus_empty(l->cpus)) {
2990 			n += sprintf(buf + n, " cpus=");
2991 			n += cpulist_scnprintf(buf + n, PAGE_SIZE - n - 50,
2992 					l->cpus);
2993 		}
2994 
2995 		if (num_online_nodes() > 1 && !nodes_empty(l->nodes)) {
2996 			n += sprintf(buf + n, " nodes=");
2997 			n += nodelist_scnprintf(buf + n, PAGE_SIZE - n - 50,
2998 					l->nodes);
2999 		}
3000 
3001 		n += sprintf(buf + n, "\n");
3002 	}
3003 
3004 	free_loc_track(&t);
3005 	if (!t.count)
3006 		n += sprintf(buf, "No data\n");
3007 	return n;
3008 }
3009 
3010 static unsigned long count_partial(struct kmem_cache_node *n)
3011 {
3012 	unsigned long flags;
3013 	unsigned long x = 0;
3014 	struct page *page;
3015 
3016 	spin_lock_irqsave(&n->list_lock, flags);
3017 	list_for_each_entry(page, &n->partial, lru)
3018 		x += page->inuse;
3019 	spin_unlock_irqrestore(&n->list_lock, flags);
3020 	return x;
3021 }
3022 
3023 enum slab_stat_type {
3024 	SL_FULL,
3025 	SL_PARTIAL,
3026 	SL_CPU,
3027 	SL_OBJECTS
3028 };
3029 
3030 #define SO_FULL		(1 << SL_FULL)
3031 #define SO_PARTIAL	(1 << SL_PARTIAL)
3032 #define SO_CPU		(1 << SL_CPU)
3033 #define SO_OBJECTS	(1 << SL_OBJECTS)
3034 
3035 static unsigned long slab_objects(struct kmem_cache *s,
3036 			char *buf, unsigned long flags)
3037 {
3038 	unsigned long total = 0;
3039 	int cpu;
3040 	int node;
3041 	int x;
3042 	unsigned long *nodes;
3043 	unsigned long *per_cpu;
3044 
3045 	nodes = kzalloc(2 * sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
3046 	per_cpu = nodes + nr_node_ids;
3047 
3048 	for_each_possible_cpu(cpu) {
3049 		struct page *page = s->cpu_slab[cpu];
3050 		int node;
3051 
3052 		if (page) {
3053 			node = page_to_nid(page);
3054 			if (flags & SO_CPU) {
3055 				int x = 0;
3056 
3057 				if (flags & SO_OBJECTS)
3058 					x = page->inuse;
3059 				else
3060 					x = 1;
3061 				total += x;
3062 				nodes[node] += x;
3063 			}
3064 			per_cpu[node]++;
3065 		}
3066 	}
3067 
3068 	for_each_online_node(node) {
3069 		struct kmem_cache_node *n = get_node(s, node);
3070 
3071 		if (flags & SO_PARTIAL) {
3072 			if (flags & SO_OBJECTS)
3073 				x = count_partial(n);
3074 			else
3075 				x = n->nr_partial;
3076 			total += x;
3077 			nodes[node] += x;
3078 		}
3079 
3080 		if (flags & SO_FULL) {
3081 			int full_slabs = atomic_read(&n->nr_slabs)
3082 					- per_cpu[node]
3083 					- n->nr_partial;
3084 
3085 			if (flags & SO_OBJECTS)
3086 				x = full_slabs * s->objects;
3087 			else
3088 				x = full_slabs;
3089 			total += x;
3090 			nodes[node] += x;
3091 		}
3092 	}
3093 
3094 	x = sprintf(buf, "%lu", total);
3095 #ifdef CONFIG_NUMA
3096 	for_each_online_node(node)
3097 		if (nodes[node])
3098 			x += sprintf(buf + x, " N%d=%lu",
3099 					node, nodes[node]);
3100 #endif
3101 	kfree(nodes);
3102 	return x + sprintf(buf + x, "\n");
3103 }
3104 
3105 static int any_slab_objects(struct kmem_cache *s)
3106 {
3107 	int node;
3108 	int cpu;
3109 
3110 	for_each_possible_cpu(cpu)
3111 		if (s->cpu_slab[cpu])
3112 			return 1;
3113 
3114 	for_each_node(node) {
3115 		struct kmem_cache_node *n = get_node(s, node);
3116 
3117 		if (n->nr_partial || atomic_read(&n->nr_slabs))
3118 			return 1;
3119 	}
3120 	return 0;
3121 }
3122 
3123 #define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
3124 #define to_slab(n) container_of(n, struct kmem_cache, kobj);
3125 
3126 struct slab_attribute {
3127 	struct attribute attr;
3128 	ssize_t (*show)(struct kmem_cache *s, char *buf);
3129 	ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
3130 };
3131 
3132 #define SLAB_ATTR_RO(_name) \
3133 	static struct slab_attribute _name##_attr = __ATTR_RO(_name)
3134 
3135 #define SLAB_ATTR(_name) \
3136 	static struct slab_attribute _name##_attr =  \
3137 	__ATTR(_name, 0644, _name##_show, _name##_store)
3138 
3139 static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
3140 {
3141 	return sprintf(buf, "%d\n", s->size);
3142 }
3143 SLAB_ATTR_RO(slab_size);
3144 
3145 static ssize_t align_show(struct kmem_cache *s, char *buf)
3146 {
3147 	return sprintf(buf, "%d\n", s->align);
3148 }
3149 SLAB_ATTR_RO(align);
3150 
3151 static ssize_t object_size_show(struct kmem_cache *s, char *buf)
3152 {
3153 	return sprintf(buf, "%d\n", s->objsize);
3154 }
3155 SLAB_ATTR_RO(object_size);
3156 
3157 static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
3158 {
3159 	return sprintf(buf, "%d\n", s->objects);
3160 }
3161 SLAB_ATTR_RO(objs_per_slab);
3162 
3163 static ssize_t order_show(struct kmem_cache *s, char *buf)
3164 {
3165 	return sprintf(buf, "%d\n", s->order);
3166 }
3167 SLAB_ATTR_RO(order);
3168 
3169 static ssize_t ctor_show(struct kmem_cache *s, char *buf)
3170 {
3171 	if (s->ctor) {
3172 		int n = sprint_symbol(buf, (unsigned long)s->ctor);
3173 
3174 		return n + sprintf(buf + n, "\n");
3175 	}
3176 	return 0;
3177 }
3178 SLAB_ATTR_RO(ctor);
3179 
3180 static ssize_t dtor_show(struct kmem_cache *s, char *buf)
3181 {
3182 	if (s->dtor) {
3183 		int n = sprint_symbol(buf, (unsigned long)s->dtor);
3184 
3185 		return n + sprintf(buf + n, "\n");
3186 	}
3187 	return 0;
3188 }
3189 SLAB_ATTR_RO(dtor);
3190 
3191 static ssize_t aliases_show(struct kmem_cache *s, char *buf)
3192 {
3193 	return sprintf(buf, "%d\n", s->refcount - 1);
3194 }
3195 SLAB_ATTR_RO(aliases);
3196 
3197 static ssize_t slabs_show(struct kmem_cache *s, char *buf)
3198 {
3199 	return slab_objects(s, buf, SO_FULL|SO_PARTIAL|SO_CPU);
3200 }
3201 SLAB_ATTR_RO(slabs);
3202 
3203 static ssize_t partial_show(struct kmem_cache *s, char *buf)
3204 {
3205 	return slab_objects(s, buf, SO_PARTIAL);
3206 }
3207 SLAB_ATTR_RO(partial);
3208 
3209 static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
3210 {
3211 	return slab_objects(s, buf, SO_CPU);
3212 }
3213 SLAB_ATTR_RO(cpu_slabs);
3214 
3215 static ssize_t objects_show(struct kmem_cache *s, char *buf)
3216 {
3217 	return slab_objects(s, buf, SO_FULL|SO_PARTIAL|SO_CPU|SO_OBJECTS);
3218 }
3219 SLAB_ATTR_RO(objects);
3220 
3221 static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
3222 {
3223 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DEBUG_FREE));
3224 }
3225 
3226 static ssize_t sanity_checks_store(struct kmem_cache *s,
3227 				const char *buf, size_t length)
3228 {
3229 	s->flags &= ~SLAB_DEBUG_FREE;
3230 	if (buf[0] == '1')
3231 		s->flags |= SLAB_DEBUG_FREE;
3232 	return length;
3233 }
3234 SLAB_ATTR(sanity_checks);
3235 
3236 static ssize_t trace_show(struct kmem_cache *s, char *buf)
3237 {
3238 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
3239 }
3240 
3241 static ssize_t trace_store(struct kmem_cache *s, const char *buf,
3242 							size_t length)
3243 {
3244 	s->flags &= ~SLAB_TRACE;
3245 	if (buf[0] == '1')
3246 		s->flags |= SLAB_TRACE;
3247 	return length;
3248 }
3249 SLAB_ATTR(trace);
3250 
3251 static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
3252 {
3253 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
3254 }
3255 
3256 static ssize_t reclaim_account_store(struct kmem_cache *s,
3257 				const char *buf, size_t length)
3258 {
3259 	s->flags &= ~SLAB_RECLAIM_ACCOUNT;
3260 	if (buf[0] == '1')
3261 		s->flags |= SLAB_RECLAIM_ACCOUNT;
3262 	return length;
3263 }
3264 SLAB_ATTR(reclaim_account);
3265 
3266 static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
3267 {
3268 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
3269 }
3270 SLAB_ATTR_RO(hwcache_align);
3271 
3272 #ifdef CONFIG_ZONE_DMA
3273 static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
3274 {
3275 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
3276 }
3277 SLAB_ATTR_RO(cache_dma);
3278 #endif
3279 
3280 static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
3281 {
3282 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
3283 }
3284 SLAB_ATTR_RO(destroy_by_rcu);
3285 
3286 static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
3287 {
3288 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
3289 }
3290 
3291 static ssize_t red_zone_store(struct kmem_cache *s,
3292 				const char *buf, size_t length)
3293 {
3294 	if (any_slab_objects(s))
3295 		return -EBUSY;
3296 
3297 	s->flags &= ~SLAB_RED_ZONE;
3298 	if (buf[0] == '1')
3299 		s->flags |= SLAB_RED_ZONE;
3300 	calculate_sizes(s);
3301 	return length;
3302 }
3303 SLAB_ATTR(red_zone);
3304 
3305 static ssize_t poison_show(struct kmem_cache *s, char *buf)
3306 {
3307 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
3308 }
3309 
3310 static ssize_t poison_store(struct kmem_cache *s,
3311 				const char *buf, size_t length)
3312 {
3313 	if (any_slab_objects(s))
3314 		return -EBUSY;
3315 
3316 	s->flags &= ~SLAB_POISON;
3317 	if (buf[0] == '1')
3318 		s->flags |= SLAB_POISON;
3319 	calculate_sizes(s);
3320 	return length;
3321 }
3322 SLAB_ATTR(poison);
3323 
3324 static ssize_t store_user_show(struct kmem_cache *s, char *buf)
3325 {
3326 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
3327 }
3328 
3329 static ssize_t store_user_store(struct kmem_cache *s,
3330 				const char *buf, size_t length)
3331 {
3332 	if (any_slab_objects(s))
3333 		return -EBUSY;
3334 
3335 	s->flags &= ~SLAB_STORE_USER;
3336 	if (buf[0] == '1')
3337 		s->flags |= SLAB_STORE_USER;
3338 	calculate_sizes(s);
3339 	return length;
3340 }
3341 SLAB_ATTR(store_user);
3342 
3343 static ssize_t validate_show(struct kmem_cache *s, char *buf)
3344 {
3345 	return 0;
3346 }
3347 
3348 static ssize_t validate_store(struct kmem_cache *s,
3349 			const char *buf, size_t length)
3350 {
3351 	if (buf[0] == '1')
3352 		validate_slab_cache(s);
3353 	else
3354 		return -EINVAL;
3355 	return length;
3356 }
3357 SLAB_ATTR(validate);
3358 
3359 static ssize_t shrink_show(struct kmem_cache *s, char *buf)
3360 {
3361 	return 0;
3362 }
3363 
3364 static ssize_t shrink_store(struct kmem_cache *s,
3365 			const char *buf, size_t length)
3366 {
3367 	if (buf[0] == '1') {
3368 		int rc = kmem_cache_shrink(s);
3369 
3370 		if (rc)
3371 			return rc;
3372 	} else
3373 		return -EINVAL;
3374 	return length;
3375 }
3376 SLAB_ATTR(shrink);
3377 
3378 static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
3379 {
3380 	if (!(s->flags & SLAB_STORE_USER))
3381 		return -ENOSYS;
3382 	return list_locations(s, buf, TRACK_ALLOC);
3383 }
3384 SLAB_ATTR_RO(alloc_calls);
3385 
3386 static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
3387 {
3388 	if (!(s->flags & SLAB_STORE_USER))
3389 		return -ENOSYS;
3390 	return list_locations(s, buf, TRACK_FREE);
3391 }
3392 SLAB_ATTR_RO(free_calls);
3393 
3394 #ifdef CONFIG_NUMA
3395 static ssize_t defrag_ratio_show(struct kmem_cache *s, char *buf)
3396 {
3397 	return sprintf(buf, "%d\n", s->defrag_ratio / 10);
3398 }
3399 
3400 static ssize_t defrag_ratio_store(struct kmem_cache *s,
3401 				const char *buf, size_t length)
3402 {
3403 	int n = simple_strtoul(buf, NULL, 10);
3404 
3405 	if (n < 100)
3406 		s->defrag_ratio = n * 10;
3407 	return length;
3408 }
3409 SLAB_ATTR(defrag_ratio);
3410 #endif
3411 
3412 static struct attribute * slab_attrs[] = {
3413 	&slab_size_attr.attr,
3414 	&object_size_attr.attr,
3415 	&objs_per_slab_attr.attr,
3416 	&order_attr.attr,
3417 	&objects_attr.attr,
3418 	&slabs_attr.attr,
3419 	&partial_attr.attr,
3420 	&cpu_slabs_attr.attr,
3421 	&ctor_attr.attr,
3422 	&dtor_attr.attr,
3423 	&aliases_attr.attr,
3424 	&align_attr.attr,
3425 	&sanity_checks_attr.attr,
3426 	&trace_attr.attr,
3427 	&hwcache_align_attr.attr,
3428 	&reclaim_account_attr.attr,
3429 	&destroy_by_rcu_attr.attr,
3430 	&red_zone_attr.attr,
3431 	&poison_attr.attr,
3432 	&store_user_attr.attr,
3433 	&validate_attr.attr,
3434 	&shrink_attr.attr,
3435 	&alloc_calls_attr.attr,
3436 	&free_calls_attr.attr,
3437 #ifdef CONFIG_ZONE_DMA
3438 	&cache_dma_attr.attr,
3439 #endif
3440 #ifdef CONFIG_NUMA
3441 	&defrag_ratio_attr.attr,
3442 #endif
3443 	NULL
3444 };
3445 
3446 static struct attribute_group slab_attr_group = {
3447 	.attrs = slab_attrs,
3448 };
3449 
3450 static ssize_t slab_attr_show(struct kobject *kobj,
3451 				struct attribute *attr,
3452 				char *buf)
3453 {
3454 	struct slab_attribute *attribute;
3455 	struct kmem_cache *s;
3456 	int err;
3457 
3458 	attribute = to_slab_attr(attr);
3459 	s = to_slab(kobj);
3460 
3461 	if (!attribute->show)
3462 		return -EIO;
3463 
3464 	err = attribute->show(s, buf);
3465 
3466 	return err;
3467 }
3468 
3469 static ssize_t slab_attr_store(struct kobject *kobj,
3470 				struct attribute *attr,
3471 				const char *buf, size_t len)
3472 {
3473 	struct slab_attribute *attribute;
3474 	struct kmem_cache *s;
3475 	int err;
3476 
3477 	attribute = to_slab_attr(attr);
3478 	s = to_slab(kobj);
3479 
3480 	if (!attribute->store)
3481 		return -EIO;
3482 
3483 	err = attribute->store(s, buf, len);
3484 
3485 	return err;
3486 }
3487 
3488 static struct sysfs_ops slab_sysfs_ops = {
3489 	.show = slab_attr_show,
3490 	.store = slab_attr_store,
3491 };
3492 
3493 static struct kobj_type slab_ktype = {
3494 	.sysfs_ops = &slab_sysfs_ops,
3495 };
3496 
3497 static int uevent_filter(struct kset *kset, struct kobject *kobj)
3498 {
3499 	struct kobj_type *ktype = get_ktype(kobj);
3500 
3501 	if (ktype == &slab_ktype)
3502 		return 1;
3503 	return 0;
3504 }
3505 
3506 static struct kset_uevent_ops slab_uevent_ops = {
3507 	.filter = uevent_filter,
3508 };
3509 
3510 decl_subsys(slab, &slab_ktype, &slab_uevent_ops);
3511 
3512 #define ID_STR_LENGTH 64
3513 
3514 /* Create a unique string id for a slab cache:
3515  * format
3516  * :[flags-]size:[memory address of kmemcache]
3517  */
3518 static char *create_unique_id(struct kmem_cache *s)
3519 {
3520 	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
3521 	char *p = name;
3522 
3523 	BUG_ON(!name);
3524 
3525 	*p++ = ':';
3526 	/*
3527 	 * First flags affecting slabcache operations. We will only
3528 	 * get here for aliasable slabs so we do not need to support
3529 	 * too many flags. The flags here must cover all flags that
3530 	 * are matched during merging to guarantee that the id is
3531 	 * unique.
3532 	 */
3533 	if (s->flags & SLAB_CACHE_DMA)
3534 		*p++ = 'd';
3535 	if (s->flags & SLAB_RECLAIM_ACCOUNT)
3536 		*p++ = 'a';
3537 	if (s->flags & SLAB_DEBUG_FREE)
3538 		*p++ = 'F';
3539 	if (p != name + 1)
3540 		*p++ = '-';
3541 	p += sprintf(p, "%07d", s->size);
3542 	BUG_ON(p > name + ID_STR_LENGTH - 1);
3543 	return name;
3544 }
3545 
3546 static int sysfs_slab_add(struct kmem_cache *s)
3547 {
3548 	int err;
3549 	const char *name;
3550 	int unmergeable;
3551 
3552 	if (slab_state < SYSFS)
3553 		/* Defer until later */
3554 		return 0;
3555 
3556 	unmergeable = slab_unmergeable(s);
3557 	if (unmergeable) {
3558 		/*
3559 		 * Slabcache can never be merged so we can use the name proper.
3560 		 * This is typically the case for debug situations. In that
3561 		 * case we can catch duplicate names easily.
3562 		 */
3563 		sysfs_remove_link(&slab_subsys.kobj, s->name);
3564 		name = s->name;
3565 	} else {
3566 		/*
3567 		 * Create a unique name for the slab as a target
3568 		 * for the symlinks.
3569 		 */
3570 		name = create_unique_id(s);
3571 	}
3572 
3573 	kobj_set_kset_s(s, slab_subsys);
3574 	kobject_set_name(&s->kobj, name);
3575 	kobject_init(&s->kobj);
3576 	err = kobject_add(&s->kobj);
3577 	if (err)
3578 		return err;
3579 
3580 	err = sysfs_create_group(&s->kobj, &slab_attr_group);
3581 	if (err)
3582 		return err;
3583 	kobject_uevent(&s->kobj, KOBJ_ADD);
3584 	if (!unmergeable) {
3585 		/* Setup first alias */
3586 		sysfs_slab_alias(s, s->name);
3587 		kfree(name);
3588 	}
3589 	return 0;
3590 }
3591 
3592 static void sysfs_slab_remove(struct kmem_cache *s)
3593 {
3594 	kobject_uevent(&s->kobj, KOBJ_REMOVE);
3595 	kobject_del(&s->kobj);
3596 }
3597 
3598 /*
3599  * Need to buffer aliases during bootup until sysfs becomes
3600  * available lest we loose that information.
3601  */
3602 struct saved_alias {
3603 	struct kmem_cache *s;
3604 	const char *name;
3605 	struct saved_alias *next;
3606 };
3607 
3608 struct saved_alias *alias_list;
3609 
3610 static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
3611 {
3612 	struct saved_alias *al;
3613 
3614 	if (slab_state == SYSFS) {
3615 		/*
3616 		 * If we have a leftover link then remove it.
3617 		 */
3618 		sysfs_remove_link(&slab_subsys.kobj, name);
3619 		return sysfs_create_link(&slab_subsys.kobj,
3620 						&s->kobj, name);
3621 	}
3622 
3623 	al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
3624 	if (!al)
3625 		return -ENOMEM;
3626 
3627 	al->s = s;
3628 	al->name = name;
3629 	al->next = alias_list;
3630 	alias_list = al;
3631 	return 0;
3632 }
3633 
3634 static int __init slab_sysfs_init(void)
3635 {
3636 	struct list_head *h;
3637 	int err;
3638 
3639 	err = subsystem_register(&slab_subsys);
3640 	if (err) {
3641 		printk(KERN_ERR "Cannot register slab subsystem.\n");
3642 		return -ENOSYS;
3643 	}
3644 
3645 	slab_state = SYSFS;
3646 
3647 	list_for_each(h, &slab_caches) {
3648 		struct kmem_cache *s =
3649 			container_of(h, struct kmem_cache, list);
3650 
3651 		err = sysfs_slab_add(s);
3652 		BUG_ON(err);
3653 	}
3654 
3655 	while (alias_list) {
3656 		struct saved_alias *al = alias_list;
3657 
3658 		alias_list = alias_list->next;
3659 		err = sysfs_slab_alias(al->s, al->name);
3660 		BUG_ON(err);
3661 		kfree(al);
3662 	}
3663 
3664 	resiliency_test();
3665 	return 0;
3666 }
3667 
3668 __initcall(slab_sysfs_init);
3669 #endif
3670