aha/mm/slub.c

/*
 * SLUB: A slab allocator that limits cache line use instead of queuing
 * objects in per cpu and per node lists.
 *
 * The allocator synchronizes using per slab locks and only
 * uses a centralized lock to manage a pool of partial slabs.
 *
 * (C) 2007 SGI, Christoph Lameter
 */

#include <linux/mm.h>
#include <linux/swap.h> /* struct reclaim_state */
#include <linux/module.h>
#include <linux/bit_spinlock.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kmemtrace.h>
#include <linux/kmemcheck.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
#include <linux/ctype.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/memory.h>
#include <linux/math64.h>
#include <linux/fault-inject.h>

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

#ifdef CONFIG_SLUB_DEBUG
#define SLABDEBUG 1
#else
#define SLABDEBUG 0
#endif

/*
 * Issues still to be resolved:
 *
 * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
 *
 * - Variable sizing of the per node arrays
 */

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

/*
 * Mininum number of partial slabs. These will be left on the partial
 * lists even if they are empty. kmem_cache_shrink may reclaim them.
 */
#define MIN_PARTIAL 5

/*
 * Maximum number of desirable partial slabs.
 * The existence of more partial slabs makes kmem_cache_shrink
 * sort the partial list by the number of objects in the.
 */
#define MAX_PARTIAL 10

#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
				SLAB_POISON | SLAB_STORE_USER)

/*
 * Debugging flags that require metadata to be stored in the slab.  These get
 * disabled when slub_debug=O is used and a cache's min order increases with
 * metadata.
 */
#define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)

/*
 * Set of flags that will prevent slab merging
 */
#define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)

#define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
		SLAB_CACHE_DMA | SLAB_NOTRACK)

#ifndef ARCH_KMALLOC_MINALIGN
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
#endif

#ifndef ARCH_SLAB_MINALIGN
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
#endif

#define OO_SHIFT	16
#define OO_MASK		((1 << OO_SHIFT) - 1)
#define MAX_OBJS_PER_PAGE	65535 /* since page.objects is u16 */

/* Internal SLUB flags */
#define __OBJECT_POISON		0x80000000 /* Poison object */
#define __SYSFS_ADD_DEFERRED	0x40000000 /* Not yet visible via sysfs */

static int kmem_size = sizeof(struct kmem_cache);

#ifdef CONFIG_SMP
static struct notifier_block slab_notifier;
#endif

static enum {
	DOWN,		/* No slab functionality available */
	PARTIAL,	/* kmem_cache_open() works but kmalloc does not */
	UP,		/* Everything works but does not show up in sysfs */
	SYSFS		/* Sysfs up */
} slab_state = DOWN;

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

/*
 * Tracking user of a slab.
 */
struct track {
	unsigned long addr;	/* Called from address */
	int cpu;		/* Was running on cpu */
	int pid;		/* Pid context */
	unsigned long when;	/* When did the operation occur */
};

enum track_item { TRACK_ALLOC, TRACK_FREE };

#ifdef CONFIG_SLUB_DEBUG
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
static void sysfs_slab_remove(struct kmem_cache *);

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

#endif

static inline void stat(struct kmem_cache_cpu *c, enum stat_item si)
{
#ifdef CONFIG_SLUB_STATS
	c->stat[si]++;
#endif
}

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

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

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

static inline struct kmem_cache_cpu *get_cpu_slab(struct kmem_cache *s, int cpu)
{
#ifdef CONFIG_SMP
	return s->cpu_slab[cpu];
#else
	return &s->cpu_slab;
#endif
}

/* Verify that a pointer has an address that is valid within a slab page */
static inline int check_valid_pointer(struct kmem_cache *s,
				struct page *page, const void *object)
{
	void *base;

	if (!object)
		return 1;

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

	return 1;
}

/*
 * Slow version of get and set free pointer.
 *
 * This version requires touching the cache lines of kmem_cache which
 * we avoid to do in the fast alloc free paths. There we obtain the offset
 * from the page struct.
 */
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
	return *(void **)(object + s->offset);
}

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

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

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

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

static inline struct kmem_cache_order_objects oo_make(int order,
						unsigned long size)
{
	struct kmem_cache_order_objects x = {
		(order << OO_SHIFT) + (PAGE_SIZE << order) / size
	};

	return x;
}

static inline int oo_order(struct kmem_cache_order_objects x)
{
	return x.x >> OO_SHIFT;
}

static inline int oo_objects(struct kmem_cache_order_objects x)
{
	return x.x & OO_MASK;
}

#ifdef CONFIG_SLUB_DEBUG
/*
 * Debug settings:
 */
#ifdef CONFIG_SLUB_DEBUG_ON
static int slub_debug = DEBUG_DEFAULT_FLAGS;
#else
static int slub_debug;
#endif

static char *slub_debug_slabs;
static int disable_higher_order_debug;

/*
 * Object debugging
 */
static void print_section(char *text, u8 *addr, unsigned int length)
{
	int i, offset;
	int newline = 1;
	char ascii[17];

	ascii[16] = 0;

	for (i = 0; i < length; i++) {
		if (newline) {
			printk(KERN_ERR "%8s 0x%p: ", text, addr + i);
			newline = 0;
		}
		printk(KERN_CONT " %02x", addr[i]);
		offset = i % 16;
		ascii[offset] = isgraph(addr[i]) ? addr[i] : '.';
		if (offset == 15) {
			printk(KERN_CONT " %s\n", ascii);
			newline = 1;
		}
	}
	if (!newline) {
		i %= 16;
		while (i < 16) {
			printk(KERN_CONT "   ");
			ascii[i] = ' ';
			i++;
		}
		printk(KERN_CONT " %s\n", ascii);
	}
}

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

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

	return p + alloc;
}

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

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

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

	set_track(s, object, TRACK_FREE, 0UL);
	set_track(s, object, TRACK_ALLOC, 0UL);
}

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

	printk(KERN_ERR "INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
		s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid);
}

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

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

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

}

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

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

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

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

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

	print_tracking(s, p);

	print_page_info(page);

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

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

	print_section("Object", p, min_t(unsigned long, s->objsize, PAGE_SIZE));

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

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

	if (s->flags & SLAB_STORE_USER)
		off += 2 * sizeof(struct track);

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

	dump_stack();
}

static void object_err(struct kmem_cache *s, struct page *page,
			u8 *object, char *reason)
{
	slab_bug(s, "%s", reason);
	print_trailer(s, page, object);
}

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

	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);
	slab_bug(s, "%s", buf);
	print_page_info(page);
	dump_stack();
}

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

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

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

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

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

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

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

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

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

	restore_bytes(s, what, value, fault, end);
	return 0;
}

/*
 * Object layout:
 *
 * object address
 * 	Bytes of the object to be managed.
 * 	If the freepointer may overlay the object then the free
 * 	pointer is the first word of the object.
 *
 * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
 * 	0xa5 (POISON_END)
 *
 * object + s->objsize
 * 	Padding to reach word boundary. This is also used for Redzoning.
 * 	Padding is extended by another word if Redzoning is enabled and
 * 	objsize == inuse.
 *
 * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
 * 	0xcc (RED_ACTIVE) for objects in use.
 *
 * object + s->inuse
 * 	Meta data starts here.
 *
 * 	A. Free pointer (if we cannot overwrite object on free)
 * 	B. Tracking data for SLAB_STORE_USER
 * 	C. Padding to reach required alignment boundary or at mininum
 * 		one word if debugging is on to be able to detect writes
 * 		before the word boundary.
 *
 *	Padding is done using 0x5a (POISON_INUSE)
 *
 * object + s->size
 * 	Nothing is used beyond s->size.
 *
 * If slabcaches are merged then the objsize and inuse boundaries are mostly
 * ignored. And therefore no slab options that rely on these boundaries
 * may be used with merged slabcaches.
 */

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

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

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

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

	return check_bytes_and_report(s, page, p, "Object padding",
				p + off, POISON_INUSE, s->size - off);
}

/* Check the pad bytes at the end of a slab page */
static int slab_pad_check(struct kmem_cache *s, struct page *page)
{
	u8 *start;
	u8 *fault;
	u8 *end;
	int length;
	int remainder;

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

	start = page_address(page);
	length = (PAGE_SIZE << compound_order(page));
	end = start + length;
	remainder = length % s->size;
	if (!remainder)
		return 1;

	fault = check_bytes(end - remainder, POISON_INUSE, remainder);
	if (!fault)
		return 1;
	while (end > fault && end[-1] == POISON_INUSE)
		end--;

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

	restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
	return 0;
}

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

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

		if (!check_bytes_and_report(s, page, object, "Redzone",
			endobject, red, s->inuse - s->objsize))
			return 0;
	} else {
		if ((s->flags & SLAB_POISON) && s->objsize < s->inuse) {
			check_bytes_and_report(s, page, p, "Alignment padding",
				endobject, POISON_INUSE, s->inuse - s->objsize);
		}
	}

	if (s->flags & SLAB_POISON) {
		if (!active && (s->flags & __OBJECT_POISON) &&
			(!check_bytes_and_report(s, page, p, "Poison", p,
					POISON_FREE, s->objsize - 1) ||
			 !check_bytes_and_report(s, page, p, "Poison",
				p + s->objsize - 1, POISON_END, 1)))
			return 0;
		/*
		 * check_pad_bytes cleans up on its own.
		 */
		check_pad_bytes(s, page, p);
	}

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

	/* Check free pointer validity */
	if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
		object_err(s, page, p, "Freepointer corrupt");
		/*
		 * No choice but to zap it and thus lose the remainder
		 * of the free objects in this slab. May cause
		 * another error because the object count is now wrong.
		 */
		set_freepointer(s, p, NULL);
		return 0;
	}
	return 1;
}

static int check_slab(struct kmem_cache *s, struct page *page)
{
	int maxobj;

	VM_BUG_ON(!irqs_disabled());

	if (!PageSlab(page)) {
		slab_err(s, page, "Not a valid slab page");
		return 0;
	}

	maxobj = (PAGE_SIZE << compound_order(page)) / s->size;
	if (page->objects > maxobj) {
		slab_err(s, page, "objects %u > max %u",
			s->name, page->objects, maxobj);
		return 0;
	}
	if (page->inuse > page->objects) {
		slab_err(s, page, "inuse %u > max %u",
			s->name, page->inuse, page->objects);
		return 0;
	}
	/* Slab_pad_check fixes things up after itself */
	slab_pad_check(s, page);
	return 1;
}

/*
 * Determine if a certain object on a page is on the freelist. Must hold the
 * slab lock to guarantee that the chains are in a consistent state.
 */
static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
{
	int nr = 0;
	void *fp = page->freelist;
	void *object = NULL;
	unsigned long max_objects;

	while (fp && nr <= page->objects) {
		if (fp == search)
			return 1;
		if (!check_valid_pointer(s, page, fp)) {
			if (object) {
				object_err(s, page, object,
					"Freechain corrupt");
				set_freepointer(s, object, NULL);
				break;
			} else {
				slab_err(s, page, "Freepointer corrupt");
				page->freelist = NULL;
				page->inuse = page->objects;
				slab_fix(s, "Freelist cleared");
				return 0;
			}
			break;
		}
		object = fp;
		fp = get_freepointer(s, object);
		nr++;
	}

	max_objects = (PAGE_SIZE << compound_order(page)) / s->size;
	if (max_objects > MAX_OBJS_PER_PAGE)
		max_objects = MAX_OBJS_PER_PAGE;

	if (page->objects != max_objects) {
		slab_err(s, page, "Wrong number of objects. Found %d but "
			"should be %d", page->objects, max_objects);
		page->objects = max_objects;
		slab_fix(s, "Number of objects adjusted.");
	}
	if (page->inuse != page->objects - nr) {
		slab_err(s, page, "Wrong object count. Counter is %d but "
			"counted were %d", page->inuse, page->objects - nr);
		page->inuse = page->objects - nr;
		slab_fix(s, "Object count adjusted.");
	}
	return search == NULL;
}

static void trace(struct kmem_cache *s, struct page *page, void *object,
								int alloc)
{
	if (s->flags & SLAB_TRACE) {
		printk(KERN_INFO "TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
			s->name,
			alloc ? "alloc" : "free",
			object, page->inuse,
			page->freelist);

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

		dump_stack();
	}
}

/*
 * Tracking of fully allocated slabs for debugging purposes.
 */
static void add_full(struct kmem_cache_node *n, struct page *page)
{
	spin_lock(&n->list_lock);
	list_add(&page->lru, &n->full);
	spin_unlock(&n->list_lock);
}

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

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

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

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

/* Tracking of the number of slabs for debugging purposes */
static inline unsigned long slabs_node(struct kmem_cache *s, int node)
{
	struct kmem_cache_node *n = get_node(s, node);

	return atomic_long_read(&n->nr_slabs);
}

static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
{
	return atomic_long_read(&n->nr_slabs);
}

static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
{
	struct kmem_cache_node *n = get_node(s, node);

	/*
	 * May be called early in order to allocate a slab for the
	 * kmem_cache_node structure. Solve the chicken-egg
	 * dilemma by deferring the increment of the count during
	 * bootstrap (see early_kmem_cache_node_alloc).
	 */
	if (!NUMA_BUILD || n) {
		atomic_long_inc(&n->nr_slabs);
		atomic_long_add(objects, &n->total_objects);
	}
}
static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
{
	struct kmem_cache_node *n = get_node(s, node);

	atomic_long_dec(&n->nr_slabs);
	atomic_long_sub(objects, &n->total_objects);
}

/* Object debug checks for alloc/free paths */
static void setup_object_debug(struct kmem_cache *s, struct page *page,
								void *object)
{
	if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
		return;

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

static int alloc_debug_processing(struct kmem_cache *s, struct page *page,
					void *object, unsigned long addr)
{
	if (!check_slab(s, page))
		goto bad;

	if (!on_freelist(s, page, object)) {
		object_err(s, page, object, "Object already allocated");
		goto bad;
	}

	if (!check_valid_pointer(s, page, object)) {
		object_err(s, page, object, "Freelist Pointer check fails");
		goto bad;
	}

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

	/* Success perform special debug activities for allocs */
	if (s->flags & SLAB_STORE_USER)
		set_track(s, object, TRACK_ALLOC, addr);
	trace(s, page, object, 1);
	init_object(s, object, 1);
	return 1;

bad:
	if (PageSlab(page)) {
		/*
		 * If this is a slab page then lets do the best we can
		 * to avoid issues in the future. Marking all objects
		 * as used avoids touching the remaining objects.
		 */
		slab_fix(s, "Marking all objects used");
		page->inuse = page->objects;
		page->freelist = NULL;
	}
	return 0;
}

static int free_debug_processing(struct kmem_cache *s, struct page *page,
					void *object, unsigned long addr)
{
	if (!check_slab(s, page))
		goto fail;

	if (!check_valid_pointer(s, page, object)) {
		slab_err(s, page, "Invalid object pointer 0x%p", object);
		goto fail;
	}

	if (on_freelist(s, page, object)) {
		object_err(s, page, object, "Object already free");
		goto fail;
	}

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

	if (unlikely(s != page->slab)) {
		if (!PageSlab(page)) {
			slab_err(s, page, "Attempt to free object(0x%p) "
				"outside of slab", object);
		} else if (!page->slab) {
			printk(KERN_ERR
				"SLUB <none>: no slab for object 0x%p.\n",
						object);
			dump_stack();
		} else
			object_err(s, page, object,
					"page slab pointer corrupt.");
		goto fail;
	}

	/* Special debug activities for freeing objects */
	if (!PageSlubFrozen(page) && !page->freelist)
		remove_full(s, page);
	if (s->flags & SLAB_STORE_USER)
		set_track(s, object, TRACK_FREE, addr);
	trace(s, page, object, 0);
	init_object(s, object, 0);
	return 1;

fail:
	slab_fix(s, "Object at 0x%p not freed", object);
	return 0;
}

static int __init setup_slub_debug(char *str)
{
	slub_debug = DEBUG_DEFAULT_FLAGS;
	if (*str++ != '=' || !*str)
		/*
		 * No options specified. Switch on full debugging.
		 */
		goto out;

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

	if (tolower(*str) == 'o') {
		/*
		 * Avoid enabling debugging on caches if its minimum order
		 * would increase as a result.
		 */
		disable_higher_order_debug = 1;
		goto out;
	}

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

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

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

__setup("slub_debug", setup_slub_debug);

static unsigned long kmem_cache_flags(unsigned long objsize,
	unsigned long flags, const char *name,
	void (*ctor)(void *))
{
	/*
	 * Enable debugging if selected on the kernel commandline.
	 */
	if (slub_debug && (!slub_debug_slabs ||
		!strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs))))
		flags |= slub_debug;

	return flags;
}
#else
static inline void setup_object_debug(struct kmem_cache *s,
			struct page *page, void *object) {}

static inline int alloc_debug_processing(struct kmem_cache *s,
	struct page *page, void *object, unsigned long addr) { return 0; }

static inline int free_debug_processing(struct kmem_cache *s,
	struct page *page, void *object, unsigned long addr) { return 0; }

static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
			{ return 1; }
static inline int check_object(struct kmem_cache *s, struct page *page,
			void *object, int active) { return 1; }
static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
static inline unsigned long kmem_cache_flags(unsigned long objsize,
	unsigned long flags, const char *name,
	void (*ctor)(void *))
{
	return flags;
}
#define slub_debug 0

#define disable_higher_order_debug 0

static inline unsigned long slabs_node(struct kmem_cache *s, int node)
							{ return 0; }
static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
							{ return 0; }
static inline void inc_slabs_node(struct kmem_cache *s, int node,
							int objects) {}
static inline void dec_slabs_node(struct kmem_cache *s, int node,
							int objects) {}
#endif

/*
 * Slab allocation and freeing
 */
static inline struct page *alloc_slab_page(gfp_t flags, int node,
					struct kmem_cache_order_objects oo)
{
	int order = oo_order(oo);

	flags |= __GFP_NOTRACK;

	if (node == -1)
		return alloc_pages(flags, order);
	else
		return alloc_pages_node(node, flags, order);
}

static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
{
	struct page *page;
	struct kmem_cache_order_objects oo = s->oo;
	gfp_t alloc_gfp;

	flags |= s->allocflags;

	/*
	 * Let the initial higher-order allocation fail under memory pressure
	 * so we fall-back to the minimum order allocation.
	 */
	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;

	page = alloc_slab_page(alloc_gfp, node, oo);
	if (unlikely(!page)) {
		oo = s->min;
		/*
		 * Allocation may have failed due to fragmentation.
		 * Try a lower order alloc if possible
		 */
		page = alloc_slab_page(flags, node, oo);
		if (!page)
			return NULL;

		stat(get_cpu_slab(s, raw_smp_processor_id()), ORDER_FALLBACK);
	}

	if (kmemcheck_enabled
		&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
		int pages = 1 << oo_order(oo);

		kmemcheck_alloc_shadow(page, oo_order(oo), flags, node);

		/*
		 * Objects from caches that have a constructor don't get
		 * cleared when they're allocated, so we need to do it here.
		 */
		if (s->ctor)
			kmemcheck_mark_uninitialized_pages(page, pages);
		else
			kmemcheck_mark_unallocated_pages(page, pages);
	}

	page->objects = oo_objects(oo);
	mod_zone_page_state(page_zone(page),
		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
		1 << oo_order(oo));

	return page;
}

static void setup_object(struct kmem_cache *s, struct page *page,
				void *object)
{
	setup_object_debug(s, page, object);
	if (unlikely(s->ctor))
		s->ctor(object);
}

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

	BUG_ON(flags & GFP_SLAB_BUG_MASK);

	page = allocate_slab(s,
		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
	if (!page)
		goto out;

	inc_slabs_node(s, page_to_nid(page), page->objects);
	page->slab = s;
	page->flags |= 1 << PG_slab;
	if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
			SLAB_STORE_USER | SLAB_TRACE))
		__SetPageSlubDebug(page);

	start = page_address(page);

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

	last = start;
	for_each_object(p, s, start, page->objects) {
		setup_object(s, page, last);
		set_freepointer(s, last, p);
		last = p;
	}
	setup_object(s, page, last);
	set_freepointer(s, last, NULL);

	page->freelist = start;
	page->inuse = 0;
out:
	return page;
}

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

	if (unlikely(SLABDEBUG && PageSlubDebug(page))) {
		void *p;

		slab_pad_check(s, page);
		for_each_object(p, s, page_address(page),
						page->objects)
			check_object(s, page, p, 0);
		__ClearPageSlubDebug(page);
	}

	kmemcheck_free_shadow(page, compound_order(page));

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

	__ClearPageSlab(page);
	reset_page_mapcount(page);
	if (current->reclaim_state)
		current->reclaim_state->reclaimed_slab += pages;
	__free_pages(page, order);
}

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

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

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

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

static void discard_slab(struct kmem_cache *s, struct page *page)
{
	dec_slabs_node(s, page_to_nid(page), page->objects);
	free_slab(s, page);
}

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

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

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

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

/*
 * Management of partially allocated slabs
 */
static void add_partial(struct kmem_cache_node *n,
				struct page *page, int tail)
{
	spin_lock(&n->list_lock);
	n->nr_partial++;
	if (tail)
		list_add_tail(&page->lru, &n->partial);
	else
		list_add(&page->lru, &n->partial);
	spin_unlock(&n->list_lock);
}

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

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

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

/*
 * Try to allocate a partial slab from a specific node.
 */
static struct page *get_partial_node(struct kmem_cache_node *n)
{
	struct page *page;

	/*
	 * Racy check. If we mistakenly see no partial slabs then we
	 * just allocate an empty slab. If we mistakenly try to get a
	 * partial slab and there is none available then get_partials()
	 * will return NULL.
	 */
	if (!n || !n->nr_partial)
		return NULL;

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

/*
 * Get a page from somewhere. Search in increasing NUMA distances.
 */
static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
{
#ifdef CONFIG_NUMA
	struct zonelist *zonelist;
	struct zoneref *z;
	struct zone *zone;
	enum zone_type high_zoneidx = gfp_zone(flags);
	struct page *page;

	/*
	 * The defrag ratio allows a configuration of the tradeoffs between
	 * inter node defragmentation and node local allocations. A lower
	 * defrag_ratio increases the tendency to do local allocations
	 * instead of attempting to obtain partial slabs from other nodes.
	 *
	 * If the defrag_ratio is set to 0 then kmalloc() always
	 * returns node local objects. If the ratio is higher then kmalloc()
	 * may return off node objects because partial slabs are obtained
	 * from other nodes and filled up.
	 *
	 * If /sys/kernel/slab/xx/defrag_ratio is set to 100 (which makes
	 * defrag_ratio = 1000) then every (well almost) allocation will
	 * first attempt to defrag slab caches on other nodes. This means
	 * scanning over all nodes to look for partial slabs which may be
	 * expensive if we do it every time we are trying to find a slab
	 * with available objects.
	 */
	if (!s->remote_node_defrag_ratio ||
			get_cycles() % 1024 > s->remote_node_defrag_ratio)
		return NULL;

	zonelist = node_zonelist(slab_node(current->mempolicy), flags);
	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
		struct kmem_cache_node *n;

		n = get_node(s, zone_to_nid(zone));

		if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
				n->nr_partial > s->min_partial) {
			page = get_partial_node(n);
			if (page)
				return page;
		}
	}
#endif
	return NULL;
}

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

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

	return get_any_partial(s, flags);
}

/*
 * Move a page back to the lists.
 *
 * Must be called with the slab lock held.
 *
 * On exit the slab lock will have been dropped.
 */
static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
{
	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
	struct kmem_cache_cpu *c = get_cpu_slab(s, smp_processor_id());

	__ClearPageSlubFrozen(page);
	if (page->inuse) {

		if (page->freelist) {
			add_partial(n, page, tail);
			stat(c, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
		} else {
			stat(c, DEACTIVATE_FULL);
			if (SLABDEBUG && PageSlubDebug(page) &&
						(s->flags & SLAB_STORE_USER))
				add_full(n, page);
		}
		slab_unlock(page);
	} else {
		stat(c, DEACTIVATE_EMPTY);
		if (n->nr_partial < s->min_partial) {
			/*
			 * Adding an empty slab to the partial slabs in order
			 * to avoid page allocator overhead. This slab needs
			 * to come after the other slabs with objects in
			 * so that the others get filled first. That way the
			 * size of the partial list stays small.
			 *
			 * kmem_cache_shrink can reclaim any empty slabs from
			 * the partial list.
			 */
			add_partial(n, page, 1);
			slab_unlock(page);
		} else {
			slab_unlock(page);
			stat(get_cpu_slab(s, raw_smp_processor_id()), FREE_SLAB);
			discard_slab(s, page);
		}
	}
}

/*
 * Remove the cpu slab
 */
static void deactivate_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
	struct page *page = c->page;
	int tail = 1;

	if (page->freelist)
		stat(c, DEACTIVATE_REMOTE_FREES);
	/*
	 * Merge cpu freelist into slab freelist. Typically we get here
	 * because both freelists are empty. So this is unlikely
	 * to occur.
	 */
	while (unlikely(c->freelist)) {
		void **object;

		tail = 0;	/* Hot objects. Put the slab first */

		/* Retrieve object from cpu_freelist */
		object = c->freelist;
		c->freelist = c->freelist[c->offset];

		/* And put onto the regular freelist */
		object[c->offset] = page->freelist;
		page->freelist = object;
		page->inuse--;
	}
	c->page = NULL;
	unfreeze_slab(s, page, tail);
}

static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
	stat(c, CPUSLAB_FLUSH);
	slab_lock(c->page);
	deactivate_slab(s, c);
}

/*
 * Flush cpu slab.
 *
 * Called from IPI handler with interrupts disabled.
 */
static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
	struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);

	if (likely(c && c->page))
		flush_slab(s, c);
}

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

	__flush_cpu_slab(s, smp_processor_id());
}

static void flush_all(struct kmem_cache *s)
{
	on_each_cpu(flush_cpu_slab, s, 1);
}

/*
 * Check if the objects in a per cpu structure fit numa
 * locality expectations.
 */
static inline int node_match(struct kmem_cache_cpu *c, int node)
{
#ifdef CONFIG_NUMA
	if (node != -1 && c->node != node)
		return 0;
#endif
	return 1;
}

static int count_free(struct page *page)
{
	return page->objects - page->inuse;
}

static unsigned long count_partial(struct kmem_cache_node *n,
					int (*get_count)(struct page *))
{
	unsigned long flags;
	unsigned long x = 0;
	struct page *page;

	spin_lock_irqsave(&n->list_lock, flags);
	list_for_each_entry(page, &n->partial, lru)
		x += get_count(page);
	spin_unlock_irqrestore(&n->list_lock, flags);
	return x;
}

static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
{
#ifdef CONFIG_SLUB_DEBUG
	return atomic_long_read(&n->total_objects);
#else
	return 0;
#endif
}

static noinline void
slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
{
	int node;

	printk(KERN_WARNING
		"SLUB: Unable to allocate memory on node %d (gfp=0x%x)\n",
		nid, gfpflags);
	printk(KERN_WARNING "  cache: %s, object size: %d, buffer size: %d, "
		"default order: %d, min order: %d\n", s->name, s->objsize,
		s->size, oo_order(s->oo), oo_order(s->min));

	if (oo_order(s->min) > get_order(s->objsize))
		printk(KERN_WARNING "  %s debugging increased min order, use "
		       "slub_debug=O to disable.\n", s->name);

	for_each_online_node(node) {
		struct kmem_cache_node *n = get_node(s, node);
		unsigned long nr_slabs;
		unsigned long nr_objs;
		unsigned long nr_free;

		if (!n)
			continue;

		nr_free  = count_partial(n, count_free);
		nr_slabs = node_nr_slabs(n);
		nr_objs  = node_nr_objs(n);

		printk(KERN_WARNING
			"  node %d: slabs: %ld, objs: %ld, free: %ld\n",
			node, nr_slabs, nr_objs, nr_free);
	}
}

/*
 * Slow path. The lockless freelist is empty or we need to perform
 * debugging duties.
 *
 * Interrupts are disabled.
 *
 * Processing is still very fast if new objects have been freed to the
 * regular freelist. In that case we simply take over the regular freelist
 * as the lockless freelist and zap the regular freelist.
 *
 * If that is not working then we fall back to the partial lists. We take the
 * first element of the freelist as the object to allocate now and move the
 * rest of the freelist to the lockless freelist.
 *
 * And if we were unable to get a new slab from the partial slab lists then
 * we need to allocate a new slab. This is the slowest path since it involves
 * a call to the page allocator and the setup of a new slab.
 */
static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
			  unsigned long addr, struct kmem_cache_cpu *c)
{
	void **object;
	struct page *new;

	/* We handle __GFP_ZERO in the caller */
	gfpflags &= ~__GFP_ZERO;

	if (!c->page)
		goto new_slab;

	slab_lock(c->page);
	if (unlikely(!node_match(c, node)))
		goto another_slab;

	stat(c, ALLOC_REFILL);

load_freelist:
	object = c->page->freelist;
	if (unlikely(!object))
		goto another_slab;
	if (unlikely(SLABDEBUG && PageSlubDebug(c->page)))
		goto debug;

	c->freelist = object[c->offset];
	c->page->inuse = c->page->objects;
	c->page->freelist = NULL;
	c->node = page_to_nid(c->page);
unlock_out:
	slab_unlock(c->page);
	stat(c, ALLOC_SLOWPATH);
	return object;

another_slab:
	deactivate_slab(s, c);

new_slab:
	new = get_partial(s, gfpflags, node);
	if (new) {
		c->page = new;
		stat(c, ALLOC_FROM_PARTIAL);
		goto load_freelist;
	}

	if (gfpflags & __GFP_WAIT)
		local_irq_enable();

	new = new_slab(s, gfpflags, node);

	if (gfpflags & __GFP_WAIT)
		local_irq_disable();

	if (new) {
		c = get_cpu_slab(s, smp_processor_id());
		stat(c, ALLOC_SLAB);
		if (c->page)
			flush_slab(s, c);
		slab_lock(new);
		__SetPageSlubFrozen(new);
		c->page = new;
		goto load_freelist;
	}
	if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit())
		slab_out_of_memory(s, gfpflags, node);
	return NULL;
debug:
	if (!alloc_debug_processing(s, c->page, object, addr))
		goto another_slab;

	c->page->inuse++;
	c->page->freelist = object[c->offset];
	c->node = -1;
	goto unlock_out;
}

/*
 * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
 * have the fastpath folded into their functions. So no function call
 * overhead for requests that can be satisfied on the fastpath.
 *
 * The fastpath works by first checking if the lockless freelist can be used.
 * If not then __slab_alloc is called for slow processing.
 *
 * Otherwise we can simply pick the next object from the lockless free list.
 */
static __always_inline void *slab_alloc(struct kmem_cache *s,
		gfp_t gfpflags, int node, unsigned long addr)
{
	void **object;
	struct kmem_cache_cpu *c;
	unsigned long flags;
	unsigned int objsize;

	gfpflags &= gfp_allowed_mask;

	lockdep_trace_alloc(gfpflags);
	might_sleep_if(gfpflags & __GFP_WAIT);

	if (should_failslab(s->objsize, gfpflags))
		return NULL;

	local_irq_save(flags);
	c = get_cpu_slab(s, smp_processor_id());
	objsize = c->objsize;
	if (unlikely(!c->freelist || !node_match(c, node)))

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

	else {
		object = c->freelist;
		c->freelist = object[c->offset];
		stat(c, ALLOC_FASTPATH);
	}
	local_irq_restore(flags);

	if (unlikely(gfpflags & __GFP_ZERO) && object)
		memset(object, 0, objsize);

	kmemcheck_slab_alloc(s, gfpflags, object, c->objsize);
	kmemleak_alloc_recursive(object, objsize, 1, s->flags, gfpflags);

	return object;
}

void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
	void *ret = slab_alloc(s, gfpflags, -1, _RET_IP_);

	trace_kmem_cache_alloc(_RET_IP_, ret, s->objsize, s->size, gfpflags);

	return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc);

#ifdef CONFIG_TRACING
void *kmem_cache_alloc_notrace(struct kmem_cache *s, gfp_t gfpflags)
{
	return slab_alloc(s, gfpflags, -1, _RET_IP_);
}
EXPORT_SYMBOL(kmem_cache_alloc_notrace);
#endif

#ifdef CONFIG_NUMA
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
	void *ret = slab_alloc(s, gfpflags, node, _RET_IP_);

	trace_kmem_cache_alloc_node(_RET_IP_, ret,
				    s->objsize, s->size, gfpflags, node);

	return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
#endif

#ifdef CONFIG_TRACING
void *kmem_cache_alloc_node_notrace(struct kmem_cache *s,
				    gfp_t gfpflags,
				    int node)
{
	return slab_alloc(s, gfpflags, node, _RET_IP_);
}
EXPORT_SYMBOL(kmem_cache_alloc_node_notrace);
#endif

/*
 * Slow patch handling. This may still be called frequently since objects
 * have a longer lifetime than the cpu slabs in most processing loads.
 *
 * So we still attempt to reduce cache line usage. Just take the slab
 * lock and free the item. If there is no additional partial page
 * handling required then we can return immediately.
 */
static void __slab_free(struct kmem_cache *s, struct page *page,
			void *x, unsigned long addr, unsigned int offset)
{
	void *prior;
	void **object = (void *)x;
	struct kmem_cache_cpu *c;

	c = get_cpu_slab(s, raw_smp_processor_id());
	stat(c, FREE_SLOWPATH);
	slab_lock(page);

	if (unlikely(SLABDEBUG && PageSlubDebug(page)))
		goto debug;

checks_ok:
	prior = object[offset] = page->freelist;
	page->freelist = object;
	page->inuse--;

	if (unlikely(PageSlubFrozen(page))) {
		stat(c, FREE_FROZEN);
		goto out_unlock;
	}

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

	/*
	 * Objects left in the slab. If it was not on the partial list before
	 * then add it.
	 */
	if (unlikely(!prior)) {
		add_partial(get_node(s, page_to_nid(page)), page, 1);
		stat(c, FREE_ADD_PARTIAL);
	}

out_unlock:
	slab_unlock(page);
	return;

slab_empty:
	if (prior) {
		/*
		 * Slab still on the partial list.
		 */
		remove_partial(s, page);
		stat(c, FREE_REMOVE_PARTIAL);
	}
	slab_unlock(page);
	stat(c, FREE_SLAB);
	discard_slab(s, page);
	return;

debug:
	if (!free_debug_processing(s, page, x, addr))
		goto out_unlock;
	goto checks_ok;
}

/*
 * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
 * can perform fastpath freeing without additional function calls.
 *
 * The fastpath is only possible if we are freeing to the current cpu slab
 * of this processor. This typically the case if we have just allocated
 * the item before.
 *
 * If fastpath is not possible then fall back to __slab_free where we deal
 * with all sorts of special processing.
 */
static __always_inline void slab_free(struct kmem_cache *s,
			struct page *page, void *x, unsigned long addr)
{
	void **object = (void *)x;
	struct kmem_cache_cpu *c;
	unsigned long flags;

	kmemleak_free_recursive(x, s->flags);
	local_irq_save(flags);
	c = get_cpu_slab(s, smp_processor_id());
	kmemcheck_slab_free(s, object, c->objsize);
	debug_check_no_locks_freed(object, c->objsize);
	if (!(s->flags & SLAB_DEBUG_OBJECTS))
		debug_check_no_obj_freed(object, c->objsize);
	if (likely(page == c->page && c->node >= 0)) {
		object[c->offset] = c->freelist;
		c->freelist = object;
		stat(c, FREE_FASTPATH);
	} else
		__slab_free(s, page, x, addr, c->offset);

	local_irq_restore(flags);
}

void kmem_cache_free(struct kmem_cache *s, void *x)
{
	struct page *page;

	page = virt_to_head_page(x);

	slab_free(s, page, x, _RET_IP_);

	trace_kmem_cache_free(_RET_IP_, x);
}
EXPORT_SYMBOL(kmem_cache_free);

/* Figure out on which slab page the object resides */
static struct page *get_object_page(const void *x)
{
	struct page *page = virt_to_head_page(x);

	if (!PageSlab(page))
		return NULL;

	return page;
}

/*
 * Object placement in a slab is made very easy because we always start at
 * offset 0. If we tune the size of the object to the alignment then we can
 * get the required alignment by putting one properly sized object after
 * another.
 *
 * Notice that the allocation order determines the sizes of the per cpu
 * caches. Each processor has always one slab available for allocations.
 * Increasing the allocation order reduces the number of times that slabs
 * must be moved on and off the partial lists and is therefore a factor in
 * locking overhead.
 */

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

/*
 * Merge control. If this is set then no merging of slab caches will occur.
 * (Could be removed. This was introduced to pacify the merge skeptics.)
 */
static int slub_nomerge;

/*
 * Calculate the order of allocation given an slab object size.
 *
 * The order of allocation has significant impact on performance and other
 * system components. Generally order 0 allocations should be preferred since
 * order 0 does not cause fragmentation in the page allocator. Larger objects
 * be problematic to put into order 0 slabs because there may be too much
 * unused space left. We go to a higher order if more than 1/16th of the slab
 * would be wasted.
 *
 * In order to reach satisfactory performance we must ensure that a minimum
 * number of objects is in one slab. Otherwise we may generate too much
 * activity on the partial lists which requires taking the list_lock. This is
 * less a concern for large slabs though which are rarely used.
 *
 * slub_max_order specifies the order where we begin to stop considering the
 * number of objects in a slab as critical. If we reach slub_max_order then
 * we try to keep the page order as low as possible. So we accept more waste
 * of space in favor of a small page order.
 *
 * Higher order allocations also allow the placement of more objects in a
 * slab and thereby reduce object handling overhead. If the user has
 * requested a higher mininum order then we start with that one instead of
 * the smallest order which will fit the object.
 */
static inline int slab_order(int size, int min_objects,
				int max_order, int fract_leftover)
{
	int order;
	int rem;
	int min_order = slub_min_order;

	if ((PAGE_SIZE << min_order) / size > MAX_OBJS_PER_PAGE)
		return get_order(size * MAX_OBJS_PER_PAGE) - 1;

	for (order = max(min_order,
				fls(min_objects * size - 1) - PAGE_SHIFT);
			order <= max_order; order++) {

		unsigned long slab_size = PAGE_SIZE << order;

		if (slab_size < min_objects * size)
			continue;

		rem = slab_size % size;

		if (rem <= slab_size / fract_leftover)
			break;

	}

	return order;
}

static inline int calculate_order(int size)
{
	int order;
	int min_objects;
	int fraction;
	int max_objects;

	/*
	 * Attempt to find best configuration for a slab. This
	 * works by first attempting to generate a layout with
	 * the best configuration and backing off gradually.
	 *
	 * First we reduce the acceptable waste in a slab. Then
	 * we reduce the minimum objects required in a slab.
	 */
	min_objects = slub_min_objects;
	if (!min_objects)
		min_objects = 4 * (fls(nr_cpu_ids) + 1);
	max_objects = (PAGE_SIZE << slub_max_order)/size;
	min_objects = min(min_objects, max_objects);

	while (min_objects > 1) {
		fraction = 16;
		while (fraction >= 4) {
			order = slab_order(size, min_objects,
						slub_max_order, fraction);
			if (order <= slub_max_order)
				return order;
			fraction /= 2;
		}
		min_objects--;
	}

	/*
	 * We were unable to place multiple objects in a slab. Now
	 * lets see if we can place a single object there.
	 */
	order = slab_order(size, 1, slub_max_order, 1);
	if (order <= slub_max_order)
		return order;

	/*
	 * Doh this slab cannot be placed using slub_max_order.
	 */
	order = slab_order(size, 1, MAX_ORDER, 1);
	if (order < MAX_ORDER)
		return order;
	return -ENOSYS;
}

/*
 * Figure out what the alignment of the objects will be.
 */
static unsigned long calculate_alignment(unsigned long flags,
		unsigned long align, unsigned long size)
{
	/*
	 * If the user wants hardware cache aligned objects then follow that
	 * suggestion if the object is sufficiently large.
	 *
	 * The hardware cache alignment cannot override the specified
	 * alignment though. If that is greater then use it.
	 */
	if (flags & SLAB_HWCACHE_ALIGN) {
		unsigned long ralign = cache_line_size();
		while (size <= ralign / 2)
			ralign /= 2;
		align = max(align, ralign);
	}

	if (align < ARCH_SLAB_MINALIGN)
		align = ARCH_SLAB_MINALIGN;

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

static void init_kmem_cache_cpu(struct kmem_cache *s,
			struct kmem_cache_cpu *c)
{
	c->page = NULL;
	c->freelist = NULL;
	c->node = 0;
	c->offset = s->offset / sizeof(void *);
	c->objsize = s->objsize;
#ifdef CONFIG_SLUB_STATS
	memset(c->stat, 0, NR_SLUB_STAT_ITEMS * sizeof(unsigned));
#endif
}

static void
init_kmem_cache_node(struct kmem_cache_node *n, struct kmem_cache *s)
{
	n->nr_partial = 0;
	spin_lock_init(&n->list_lock);
	INIT_LIST_HEAD(&n->partial);
#ifdef CONFIG_SLUB_DEBUG
	atomic_long_set(&n->nr_slabs, 0);
	atomic_long_set(&n->total_objects, 0);
	INIT_LIST_HEAD(&n->full);
#endif
}

#ifdef CONFIG_SMP
/*
 * Per cpu array for per cpu structures.
 *
 * The per cpu array places all kmem_cache_cpu structures from one processor
 * close together meaning that it becomes possible that multiple per cpu
 * structures are contained in one cacheline. This may be particularly
 * beneficial for the kmalloc caches.
 *
 * A desktop system typically has around 60-80 slabs. With 100 here we are
 * likely able to get per cpu structures for all caches from the array defined
 * here. We must be able to cover all kmalloc caches during bootstrap.
 *
 * If the per cpu array is exhausted then fall back to kmalloc
 * of individual cachelines. No sharing is possible then.
 */
#define NR_KMEM_CACHE_CPU 100

static DEFINE_PER_CPU(struct kmem_cache_cpu [NR_KMEM_CACHE_CPU],
		      kmem_cache_cpu);

static DEFINE_PER_CPU(struct kmem_cache_cpu *, kmem_cache_cpu_free);
static DECLARE_BITMAP(kmem_cach_cpu_free_init_once, CONFIG_NR_CPUS);

static struct kmem_cache_cpu *alloc_kmem_cache_cpu(struct kmem_cache *s,
							int cpu, gfp_t flags)
{
	struct kmem_cache_cpu *c = per_cpu(kmem_cache_cpu_free, cpu);

	if (c)
		per_cpu(kmem_cache_cpu_free, cpu) =
				(void *)c->freelist;
	else {
		/* Table overflow: So allocate ourselves */
		c = kmalloc_node(
			ALIGN(sizeof(struct kmem_cache_cpu), cache_line_size()),
			flags, cpu_to_node(cpu));
		if (!c)
			return NULL;
	}

	init_kmem_cache_cpu(s, c);
	return c;
}

static void free_kmem_cache_cpu(struct kmem_cache_cpu *c, int cpu)
{
	if (c < per_cpu(kmem_cache_cpu, cpu) ||
			c >= per_cpu(kmem_cache_cpu, cpu) + NR_KMEM_CACHE_CPU) {
		kfree(c);
		return;
	}
	c->freelist = (void *)per_cpu(kmem_cache_cpu_free, cpu);
	per_cpu(kmem_cache_cpu_free, cpu) = c;
}

static void free_kmem_cache_cpus(struct kmem_cache *s)
{
	int cpu;

	for_each_online_cpu(cpu) {
		struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);

		if (c) {
			s->cpu_slab[cpu] = NULL;
			free_kmem_cache_cpu(c, cpu);
		}
	}
}

static int alloc_kmem_cache_cpus(struct kmem_cache *s, gfp_t flags)
{
	int cpu;

	for_each_online_cpu(cpu) {
		struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);

		if (c)
			continue;

		c = alloc_kmem_cache_cpu(s, cpu, flags);
		if (!c) {
			free_kmem_cache_cpus(s);
			return 0;
		}
		s->cpu_slab[cpu] = c;
	}
	return 1;
}

/*
 * Initialize the per cpu array.
 */
static void init_alloc_cpu_cpu(int cpu)
{
	int i;

	if (cpumask_test_cpu(cpu, to_cpumask(kmem_cach_cpu_free_init_once)))
		return;

	for (i = NR_KMEM_CACHE_CPU - 1; i >= 0; i--)
		free_kmem_cache_cpu(&per_cpu(kmem_cache_cpu, cpu)[i], cpu);

	cpumask_set_cpu(cpu, to_cpumask(kmem_cach_cpu_free_init_once));
}

static void __init init_alloc_cpu(void)
{
	int cpu;

	for_each_online_cpu(cpu)
		init_alloc_cpu_cpu(cpu);
  }

#else
static inline void free_kmem_cache_cpus(struct kmem_cache *s) {}
static inline void init_alloc_cpu(void) {}

static inline int alloc_kmem_cache_cpus(struct kmem_cache *s, gfp_t flags)
{
	init_kmem_cache_cpu(s, &s->cpu_slab);
	return 1;
}
#endif

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

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

	page = new_slab(kmalloc_caches, gfpflags, node);

	BUG_ON(!page);
	if (page_to_nid(page) != node) {
		printk(KERN_ERR "SLUB: Unable to allocate memory from "
				"node %d\n", node);
		printk(KERN_ERR "SLUB: Allocating a useless per node structure "
				"in order to be able to continue\n");
	}

	n = page->freelist;
	BUG_ON(!n);
	page->freelist = get_freepointer(kmalloc_caches, n);
	page->inuse++;
	kmalloc_caches->node[node] = n;
#ifdef CONFIG_SLUB_DEBUG
	init_object(kmalloc_caches, n, 1);
	init_tracking(kmalloc_caches, n);
#endif
	init_kmem_cache_node(n, kmalloc_caches);
	inc_slabs_node(kmalloc_caches, node, page->objects);

	/*
	 * lockdep requires consistent irq usage for each lock
	 * so even though there cannot be a race this early in
	 * the boot sequence, we still disable irqs.
	 */
	local_irq_save(flags);
	add_partial(n, page, 0);
	local_irq_restore(flags);
}

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

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

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

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

	for_each_node_state(node, N_NORMAL_MEMORY) {
		struct kmem_cache_node *n;

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

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

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

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

static void set_min_partial(struct kmem_cache *s, unsigned long min)
{
	if (min < MIN_PARTIAL)
		min = MIN_PARTIAL;
	else if (min > MAX_PARTIAL)
		min = MAX_PARTIAL;
	s->min_partial = min;
}

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

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

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


	/*
	 * If we are Redzoning then check if there is some space between the
	 * end of the object and the free pointer. If not then add an
	 * additional word to have some bytes to store Redzone information.
	 */
	if ((flags & SLAB_RED_ZONE) && size == s->objsize)
		size += sizeof(void *);
#endif

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

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

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

	if (flags & SLAB_RED_ZONE)
		/*
		 * Add some empty padding so that we can catch
		 * overwrites from earlier objects rather than let
		 * tracking information or the free pointer be
		 * corrupted if a user writes before the start
		 * of the object.
		 */
		size += sizeof(void *);
#endif

	/*
	 * Determine the alignment based on various parameters that the
	 * user specified and the dynamic determination of cache line size
	 * on bootup.
	 */
	align = calculate_alignment(flags, align, s->objsize);
	s->align = align;

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

	if (order < 0)
		return 0;

	s->allocflags = 0;
	if (order)
		s->allocflags |= __GFP_COMP;

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

	if (s->flags & SLAB_RECLAIM_ACCOUNT)
		s->allocflags |= __GFP_RECLAIMABLE;

	/*
	 * Determine the number of objects per slab
	 */
	s->oo = oo_make(order, size);
	s->min = oo_make(get_order(size), size);
	if (oo_objects(s->oo) > oo_objects(s->max))
		s->max = s->oo;

	return !!oo_objects(s->oo);

}

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

	if (!calculate_sizes(s, -1))
		goto error;
	if (disable_higher_order_debug) {
		/*
		 * Disable debugging flags that store metadata if the min slab
		 * order increased.
		 */
		if (get_order(s->size) > get_order(s->objsize)) {
			s->flags &= ~DEBUG_METADATA_FLAGS;
			s->offset = 0;
			if (!calculate_sizes(s, -1))
				goto error;
		}
	}

	/*
	 * The larger the object size is, the more pages we want on the partial
	 * list to avoid pounding the page allocator excessively.
	 */
	set_min_partial(s, ilog2(s->size));
	s->refcount = 1;
#ifdef CONFIG_NUMA
	s->remote_node_defrag_ratio = 1000;
#endif
	if (!init_kmem_cache_nodes(s, gfpflags & ~SLUB_DMA))
		goto error;

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

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

	page = get_object_page(object);

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

	if (!check_valid_pointer(s, page, object))
		return 0;

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

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

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

static void list_slab_objects(struct kmem_cache *s, struct page *page,
							const char *text)
{
#ifdef CONFIG_SLUB_DEBUG
	void *addr = page_address(page);
	void *p;
	DECLARE_BITMAP(map, page->objects);

	bitmap_zero(map, page->objects);
	slab_err(s, page, "%s", text);
	slab_lock(page);
	for_each_free_object(p, s, page->freelist)
		set_bit(slab_index(p, s, addr), map);

	for_each_object(p, s, addr, page->objects) {

		if (!test_bit(slab_index(p, s, addr), map)) {
			printk(KERN_ERR "INFO: Object 0x%p @offset=%tu\n",
							p, p - addr);
			print_tracking(s, p);
		}
	}
	slab_unlock(page);
#endif
}

/*
 * Attempt to free all partial slabs on a node.
 */
static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
{
	unsigned long flags;
	struct page *page, *h;

	spin_lock_irqsave(&n->list_lock, flags);
	list_for_each_entry_safe(page, h, &n->partial, lru) {
		if (!page->inuse) {
			list_del(&page->lru);
			discard_slab(s, page);
			n->nr_partial--;
		} else {
			list_slab_objects(s, page,
				"Objects remaining on kmem_cache_close()");
		}
	}
	spin_unlock_irqrestore(&n->list_lock, flags);
}

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

	flush_all(s);

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

		free_partial(s, n);
		if (n->nr_partial || slabs_node(s, node))
			return 1;
	}
	free_kmem_cache_nodes(s);
	return 0;
}

/*
 * Close a cache and release the kmem_cache structure
 * (must be used for caches created using kmem_cache_create)
 */
void kmem_cache_destroy(struct kmem_cache *s)
{
	down_write(&slub_lock);
	s->refcount--;
	if (!s->refcount) {
		list_del(&s->list);
		up_write(&slub_lock);
		if (kmem_cache_close(s)) {
			printk(KERN_ERR "SLUB %s: %s called for cache that "
				"still has objects.\n", s->name, __func__);
			dump_stack();
		}
		if (s->flags & SLAB_DESTROY_BY_RCU)
			rcu_barrier();
		sysfs_slab_remove(s);
	} else
		up_write(&slub_lock);
}
EXPORT_SYMBOL(kmem_cache_destroy);

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

struct kmem_cache kmalloc_caches[SLUB_PAGE_SHIFT] __cacheline_aligned;
EXPORT_SYMBOL(kmalloc_caches);

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

	return 1;
}

__setup("slub_min_order=", setup_slub_min_order);

static int __init setup_slub_max_order(char *str)
{
	get_option(&str, &slub_max_order);
	slub_max_order = min(slub_max_order, MAX_ORDER - 1);

	return 1;
}

__setup("slub_max_order=", setup_slub_max_order);

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

	return 1;
}

__setup("slub_min_objects=", setup_slub_min_objects);

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

__setup("slub_nomerge", setup_slub_nomerge);

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

	if (gfp_flags & SLUB_DMA)
		flags = SLAB_CACHE_DMA;

	/*
	 * This function is called with IRQs disabled during early-boot on
	 * single CPU so there's no need to take slub_lock here.
	 */
	if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
								flags, NULL))
		goto panic;

	list_add(&s->list, &slab_caches);

	if (sysfs_slab_add(s))
		goto panic;
	return s;

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

#ifdef CONFIG_ZONE_DMA
static struct kmem_cache *kmalloc_caches_dma[SLUB_PAGE_SHIFT];

static void sysfs_add_func(struct work_struct *w)
{
	struct kmem_cache *s;

	down_write(&slub_lock);
	list_for_each_entry(s, &slab_caches, list) {
		if (s->flags & __SYSFS_ADD_DEFERRED) {
			s->flags &= ~__SYSFS_ADD_DEFERRED;
			sysfs_slab_add(s);
		}
	}
	up_write(&slub_lock);
}

static DECLARE_WORK(sysfs_add_work, sysfs_add_func);

static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
{
	struct kmem_cache *s;
	char *text;
	size_t realsize;
	unsigned long slabflags;

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

	/* Dynamically create dma cache */
	if (flags & __GFP_WAIT)
		down_write(&slub_lock);
	else {
		if (!down_write_trylock(&slub_lock))
			goto out;
	}

	if (kmalloc_caches_dma[index])
		goto unlock_out;

	realsize = kmalloc_caches[index].objsize;
	text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
			 (unsigned int)realsize);
	s = kmalloc(kmem_size, flags & ~SLUB_DMA);

	/*
	 * Must defer sysfs creation to a workqueue because we don't know
	 * what context we are called from. Before sysfs comes up, we don't
	 * need to do anything because our sysfs initcall will start by
	 * adding all existing slabs to sysfs.
	 */
	slabflags = SLAB_CACHE_DMA|SLAB_NOTRACK;
	if (slab_state >= SYSFS)
		slabflags |= __SYSFS_ADD_DEFERRED;

	if (!s || !text || !kmem_cache_open(s, flags, text,
			realsize, ARCH_KMALLOC_MINALIGN, slabflags, NULL)) {
		kfree(s);
		kfree(text);
		goto unlock_out;
	}

	list_add(&s->list, &slab_caches);
	kmalloc_caches_dma[index] = s;

	if (slab_state >= SYSFS)
		schedule_work(&sysfs_add_work);

unlock_out:
	up_write(&slub_lock);
out:
	return kmalloc_caches_dma[index];
}
#endif

/*
 * Conversion table for small slabs sizes / 8 to the index in the
 * kmalloc array. This is necessary for slabs < 192 since we have non power
 * of two cache sizes there. The size of larger slabs can be determined using
 * fls.
 */
static s8 size_index[24] = {
	3,	/* 8 */
	4,	/* 16 */
	5,	/* 24 */
	5,	/* 32 */
	6,	/* 40 */
	6,	/* 48 */
	6,	/* 56 */
	6,	/* 64 */
	1,	/* 72 */
	1,	/* 80 */
	1,	/* 88 */
	1,	/* 96 */
	7,	/* 104 */
	7,	/* 112 */
	7,	/* 120 */
	7,	/* 128 */
	2,	/* 136 */
	2,	/* 144 */
	2,	/* 152 */
	2,	/* 160 */
	2,	/* 168 */
	2,	/* 176 */
	2,	/* 184 */
	2	/* 192 */
};

static inline int size_index_elem(size_t bytes)
{
	return (bytes - 1) / 8;
}

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

	if (size <= 192) {
		if (!size)
			return ZERO_SIZE_PTR;

		index = size_index[size_index_elem(size)];
	} else
		index = fls(size - 1);

#ifdef CONFIG_ZONE_DMA
	if (unlikely((flags & SLUB_DMA)))
		return dma_kmalloc_cache(index, flags);

#endif
	return &kmalloc_caches[index];
}

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

	if (unlikely(size > SLUB_MAX_SIZE))
		return kmalloc_large(size, flags);

	s = get_slab(size, flags);

	if (unlikely(ZERO_OR_NULL_PTR(s)))
		return s;

	ret = slab_alloc(s, flags, -1, _RET_IP_);

	trace_kmalloc(_RET_IP_, ret, size, s->size, flags);

	return ret;
}
EXPORT_SYMBOL(__kmalloc);

static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
{
	struct page *page;
	void *ptr = NULL;

	flags |= __GFP_COMP | __GFP_NOTRACK;
	page = alloc_pages_node(node, flags, get_order(size));
	if (page)
		ptr = page_address(page);

	kmemleak_alloc(ptr, size, 1, flags);
	return ptr;
}

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