SLUB core

This is a new slab allocator which was motivated by the complexity of the
existing code in mm/slab.c. It attempts to address a variety of concerns
with the existing implementation.

A. Management of object queues

   A particular concern was the complex management of the numerous object
   queues in SLAB. SLUB has no such queues. Instead we dedicate a slab for
   each allocating CPU and use objects from a slab directly instead of
   queueing them up.

B. Storage overhead of object queues

   SLAB Object queues exist per node, per CPU. The alien cache queue even
   has a queue array that contain a queue for each processor on each
   node. For very large systems the number of queues and the number of
   objects that may be caught in those queues grows exponentially. On our
   systems with 1k nodes / processors we have several gigabytes just tied up
   for storing references to objects for those queues  This does not include
   the objects that could be on those queues. One fears that the whole
   memory of the machine could one day be consumed by those queues.

C. SLAB meta data overhead

   SLAB has overhead at the beginning of each slab. This means that data
   cannot be naturally aligned at the beginning of a slab block. SLUB keeps
   all meta data in the corresponding page_struct. Objects can be naturally
   aligned in the slab. F.e. a 128 byte object will be aligned at 128 byte
   boundaries and can fit tightly into a 4k page with no bytes left over.
   SLAB cannot do this.

D. SLAB has a complex cache reaper

   SLUB does not need a cache reaper for UP systems. On SMP systems
   the per CPU slab may be pushed back into partial list but that
   operation is simple and does not require an iteration over a list
   of objects. SLAB expires per CPU, shared and alien object queues
   during cache reaping which may cause strange hold offs.

E. SLAB has complex NUMA policy layer support

   SLUB pushes NUMA policy handling into the page allocator. This means that
   allocation is coarser (SLUB does interleave on a page level) but that
   situation was also present before 2.6.13. SLABs application of
   policies to individual slab objects allocated in SLAB is
   certainly a performance concern due to the frequent references to
   memory policies which may lead a sequence of objects to come from
   one node after another. SLUB will get a slab full of objects
   from one node and then will switch to the next.

F. Reduction of the size of partial slab lists

   SLAB has per node partial lists. This means that over time a large
   number of partial slabs may accumulate on those lists. These can
   only be reused if allocator occur on specific nodes. SLUB has a global
   pool of partial slabs and will consume slabs from that pool to
   decrease fragmentation.

G. Tunables

   SLAB has sophisticated tuning abilities for each slab cache. One can
   manipulate the queue sizes in detail. However, filling the queues still
   requires the uses of the spin lock to check out slabs. SLUB has a global
   parameter (min_slab_order) for tuning. Increasing the minimum slab
   order can decrease the locking overhead. The bigger the slab order the
   less motions of pages between per CPU and partial lists occur and the
   better SLUB will be scaling.

G. Slab merging

   We often have slab caches with similar parameters. SLUB detects those
   on boot up and merges them into the corresponding general caches. This
   leads to more effective memory use. About 50% of all caches can
   be eliminated through slab merging. This will also decrease
   slab fragmentation because partial allocated slabs can be filled
   up again. Slab merging can be switched off by specifying
   slub_nomerge on boot up.

   Note that merging can expose heretofore unknown bugs in the kernel
   because corrupted objects may now be placed differently and corrupt
   differing neighboring objects. Enable sanity checks to find those.

H. Diagnostics

   The current slab diagnostics are difficult to use and require a
   recompilation of the kernel. SLUB contains debugging code that
   is always available (but is kept out of the hot code paths).
   SLUB diagnostics can be enabled via the "slab_debug" option.
   Parameters can be specified to select a single or a group of
   slab caches for diagnostics. This means that the system is running
   with the usual performance and it is much more likely that
   race conditions can be reproduced.

I. Resiliency

   If basic sanity checks are on then SLUB is capable of detecting
   common error conditions and recover as best as possible to allow the
   system to continue.

J. Tracing

   Tracing can be enabled via the slab_debug=T,<slabcache> option
   during boot. SLUB will then protocol all actions on that slabcache
   and dump the object contents on free.

K. On demand DMA cache creation.

   Generally DMA caches are not needed. If a kmalloc is used with
   __GFP_DMA then just create this single slabcache that is needed.
   For systems that have no ZONE_DMA requirement the support is
   completely eliminated.

L. Performance increase

   Some benchmarks have shown speed improvements on kernbench in the
   range of 5-10%. The locking overhead of slub is based on the
   underlying base allocation size. If we can reliably allocate
   larger order pages then it is possible to increase slub
   performance much further. The anti-fragmentation patches may
   enable further performance increases.

Tested on:
i386 UP + SMP, x86_64 UP + SMP + NUMA emulation, IA64 NUMA + Simulator

SLUB Boot options

slub_nomerge		Disable merging of slabs
slub_min_order=x	Require a minimum order for slab caches. This
			increases the managed chunk size and therefore
			reduces meta data and locking overhead.
slub_min_objects=x	Mininum objects per slab. Default is 8.
slub_max_order=x	Avoid generating slabs larger than order specified.
slub_debug		Enable all diagnostics for all caches
slub_debug=<options>	Enable selective options for all caches
slub_debug=<o>,<cache>	Enable selective options for a certain set of
			caches

Available Debug options
F		Double Free checking, sanity and resiliency
R		Red zoning
P		Object / padding poisoning
U		Track last free / alloc
T		Trace all allocs / frees (only use for individual slabs).

To use SLUB: Apply this patch and then select SLUB as the default slab
allocator.

[hugh@veritas.com: fix an oops-causing locking error]
[akpm@linux-foundation.org: various stupid cleanups and small fixes]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3145 insertions, 0 deletions

diff --git a/mm/Makefile b/mm/Makefile
index f3c077e..1887148 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o
 obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
 obj-$(CONFIG_SLOB) += slob.o
 obj-$(CONFIG_SLAB) += slab.o
+obj-$(CONFIG_SLUB) += slub.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
 obj-$(CONFIG_MIGRATION) += migrate.o
diff --git a/mm/slub.c b/mm/slub.c
new file mode 100644
index 0000000..0cd56bd
--- /dev/null
+++ b/mm/slub.c
@@ -0,0 +1,3144 @@
+/*
+ * SLUB: A slab allocator that limits cache line use instead of queuing
+ * objects in per cpu and per node lists.
+ *
+ * The allocator synchronizes using per slab locks and only
+ * uses a centralized lock to manage a pool of partial slabs.
+ *
+ * (C) 2007 SGI, Christoph Lameter <clameter@sgi.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/bit_spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/mempolicy.h>
+#include <linux/ctype.h>
+#include <linux/kallsyms.h>
+
+/*
+ * Lock order:
+ *   1. slab_lock(page)
+ *   2. slab->list_lock
+ *
+ *   The slab_lock protects operations on the object of a particular
+ *   slab and its metadata in the page struct. If the slab lock
+ *   has been taken then no allocations nor frees can be performed
+ *   on the objects in the slab nor can the slab be added or removed
+ *   from the partial or full lists since this would mean modifying
+ *   the page_struct of the slab.
+ *
+ *   The list_lock protects the partial and full list on each node and
+ *   the partial slab counter. If taken then no new slabs may be added or
+ *   removed from the lists nor make the number of partial slabs be modified.
+ *   (Note that the total number of slabs is an atomic value that may be
+ *   modified without taking the list lock).
+ *
+ *   The list_lock is a centralized lock and thus we avoid taking it as
+ *   much as possible. As long as SLUB does not have to handle partial
+ *   slabs, operations can continue without any centralized lock. F.e.
+ *   allocating a long series of objects that fill up slabs does not require
+ *   the list lock.
+ *
+ *   The lock order is sometimes inverted when we are trying to get a slab
+ *   off a list. We take the list_lock and then look for a page on the list
+ *   to use. While we do that objects in the slabs may be freed. We can
+ *   only operate on the slab if we have also taken the slab_lock. So we use
+ *   a slab_trylock() on the slab. If trylock was successful then no frees
+ *   can occur anymore and we can use the slab for allocations etc. If the
+ *   slab_trylock() does not succeed then frees are in progress in the slab and
+ *   we must stay away from it for a while since we may cause a bouncing
+ *   cacheline if we try to acquire the lock. So go onto the next slab.
+ *   If all pages are busy then we may allocate a new slab instead of reusing
+ *   a partial slab. A new slab has noone operating on it and thus there is
+ *   no danger of cacheline contention.
+ *
+ *   Interrupts are disabled during allocation and deallocation in order to
+ *   make the slab allocator safe to use in the context of an irq. In addition
+ *   interrupts are disabled to ensure that the processor does not change
+ *   while handling per_cpu slabs, due to kernel preemption.
+ *
+ * SLUB assigns one slab for allocation to each processor.
+ * Allocations only occur from these slabs called cpu slabs.
+ *
+ * Slabs with free elements are kept on a partial list.
+ * There is no list for full slabs. If an object in a full slab is
+ * freed then the slab will show up again on the partial lists.
+ * Otherwise there is no need to track full slabs unless we have to
+ * track full slabs for debugging purposes.
+ *
+ * Slabs are freed when they become empty. Teardown and setup is
+ * minimal so we rely on the page allocators per cpu caches for
+ * fast frees and allocs.
+ *
+ * Overloading of page flags that are otherwise used for LRU management.
+ *
+ * PageActive 		The slab is used as a cpu cache. Allocations
+ * 			may be performed from the slab. The slab is not
+ * 			on any slab list and cannot be moved onto one.
+ *
+ * PageError		Slab requires special handling due to debug
+ * 			options set. This moves	slab handling out of
+ * 			the fast path.
+ */
+
+/*
+ * Issues still to be resolved:
+ *
+ * - The per cpu array is updated for each new slab and and is a remote
+ *   cacheline for most nodes. This could become a bouncing cacheline given
+ *   enough frequent updates. There are 16 pointers in a cacheline.so at
+ *   max 16 cpus could compete. Likely okay.
+ *
+ * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
+ *
+ * - Support DEBUG_SLAB_LEAK. Trouble is we do not know where the full
+ *   slabs are in SLUB.
+ *
+ * - SLAB_DEBUG_INITIAL is not supported but I have never seen a use of
+ *   it.
+ *
+ * - Variable sizing of the per node arrays
+ */
+
+/* Enable to test recovery from slab corruption on boot */
+#undef SLUB_RESILIENCY_TEST
+
+#if PAGE_SHIFT <= 12
+
+/*
+ * Small page size. Make sure that we do not fragment memory
+ */
+#define DEFAULT_MAX_ORDER 1
+#define DEFAULT_MIN_OBJECTS 4
+
+#else
+
+/*
+ * Large page machines are customarily able to handle larger
+ * page orders.
+ */
+#define DEFAULT_MAX_ORDER 2
+#define DEFAULT_MIN_OBJECTS 8
+
+#endif
+
+/*
+ * Flags from the regular SLAB that SLUB does not support:
+ */
+#define SLUB_UNIMPLEMENTED (SLAB_DEBUG_INITIAL)
+
+#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
+				SLAB_POISON | SLAB_STORE_USER)
+/*
+ * Set of flags that will prevent slab merging
+ */
+#define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
+		SLAB_TRACE | SLAB_DESTROY_BY_RCU)
+
+#define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
+		SLAB_CACHE_DMA)
+
+#ifndef ARCH_KMALLOC_MINALIGN
+#define ARCH_KMALLOC_MINALIGN sizeof(void *)
+#endif
+
+#ifndef ARCH_SLAB_MINALIGN
+#define ARCH_SLAB_MINALIGN sizeof(void *)
+#endif
+
+/* Internal SLUB flags */
+#define __OBJECT_POISON 0x80000000	/* Poison object */
+
+static int kmem_size = sizeof(struct kmem_cache);
+
+#ifdef CONFIG_SMP
+static struct notifier_block slab_notifier;
+#endif
+
+static enum {
+	DOWN,		/* No slab functionality available */
+	PARTIAL,	/* kmem_cache_open() works but kmalloc does not */
+	UP,		/* Everything works */
+	SYSFS		/* Sysfs up */
+} slab_state = DOWN;
+
+/* A list of all slab caches on the system */
+static DECLARE_RWSEM(slub_lock);
+LIST_HEAD(slab_caches);
+
+#ifdef CONFIG_SYSFS
+static int sysfs_slab_add(struct kmem_cache *);
+static int sysfs_slab_alias(struct kmem_cache *, const char *);
+static void sysfs_slab_remove(struct kmem_cache *);
+#else
+static int sysfs_slab_add(struct kmem_cache *s) { return 0; }
+static int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; }
+static void sysfs_slab_remove(struct kmem_cache *s) {}
+#endif
+
+/********************************************************************
+ * 			Core slab cache functions
+ *******************************************************************/
+
+int slab_is_available(void)
+{
+	return slab_state >= UP;
+}
+
+static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
+{
+#ifdef CONFIG_NUMA
+	return s->node[node];
+#else
+	return &s->local_node;
+#endif
+}
+
+/*
+ * Object debugging
+ */
+static void print_section(char *text, u8 *addr, unsigned int length)
+{
+	int i, offset;
+	int newline = 1;
+	char ascii[17];
+
+	ascii[16] = 0;
+
+	for (i = 0; i < length; i++) {
+		if (newline) {
+			printk(KERN_ERR "%10s 0x%p: ", text, addr + i);
+			newline = 0;
+		}
+		printk(" %02x", addr[i]);
+		offset = i % 16;
+		ascii[offset] = isgraph(addr[i]) ? addr[i] : '.';
+		if (offset == 15) {
+			printk(" %s\n",ascii);
+			newline = 1;
+		}
+	}
+	if (!newline) {
+		i %= 16;
+		while (i < 16) {
+			printk("   ");
+			ascii[i] = ' ';
+			i++;
+		}
+		printk(" %s\n", ascii);
+	}
+}
+
+/*
+ * Slow version of get and set free pointer.
+ *
+ * This requires touching the cache lines of kmem_cache.
+ * The offset can also be obtained from the page. In that
+ * case it is in the cacheline that we already need to touch.
+ */
+static void *get_freepointer(struct kmem_cache *s, void *object)
+{
+	return *(void **)(object + s->offset);
+}
+
+static void set_freepointer(struct kmem_cache *s, void *object, void *fp)
+{
+	*(void **)(object + s->offset) = fp;
+}
+
+/*
+ * Tracking user of a slab.
+ */
+struct track {
+	void *addr;		/* Called from address */
+	int cpu;		/* Was running on cpu */
+	int pid;		/* Pid context */
+	unsigned long when;	/* When did the operation occur */
+};
+
+enum track_item { TRACK_ALLOC, TRACK_FREE };
+
+static struct track *get_track(struct kmem_cache *s, void *object,
+	enum track_item alloc)
+{
+	struct track *p;
+
+	if (s->offset)
+		p = object + s->offset + sizeof(void *);
+	else
+		p = object + s->inuse;
+
+	return p + alloc;
+}
+
+static void set_track(struct kmem_cache *s, void *object,
+				enum track_item alloc, void *addr)
+{
+	struct track *p;
+
+	if (s->offset)
+		p = object + s->offset + sizeof(void *);
+	else
+		p = object + s->inuse;
+
+	p += alloc;
+	if (addr) {
+		p->addr = addr;
+		p->cpu = smp_processor_id();
+		p->pid = current ? current->pid : -1;
+		p->when = jiffies;
+	} else
+		memset(p, 0, sizeof(struct track));
+}
+
+#define set_tracking(__s, __o, __a) set_track(__s, __o, __a, \
+			__builtin_return_address(0))
+
+static void init_tracking(struct kmem_cache *s, void *object)
+{
+	if (s->flags & SLAB_STORE_USER) {
+		set_track(s, object, TRACK_FREE, NULL);
+		set_track(s, object, TRACK_ALLOC, NULL);
+	}
+}
+
+static void print_track(const char *s, struct track *t)
+{
+	if (!t->addr)
+		return;
+
+	printk(KERN_ERR "%s: ", s);
+	__print_symbol("%s", (unsigned long)t->addr);
+	printk(" jiffies_ago=%lu cpu=%u pid=%d\n", jiffies - t->when, t->cpu, t->pid);
+}
+
+static void print_trailer(struct kmem_cache *s, u8 *p)
+{
+	unsigned int off;	/* Offset of last byte */
+
+	if (s->flags & SLAB_RED_ZONE)
+		print_section("Redzone", p + s->objsize,
+			s->inuse - s->objsize);
+
+	printk(KERN_ERR "FreePointer 0x%p -> 0x%p\n",
+			p + s->offset,
+			get_freepointer(s, p));
+
+	if (s->offset)
+		off = s->offset + sizeof(void *);
+	else
+		off = s->inuse;
+
+	if (s->flags & SLAB_STORE_USER) {
+		print_track("Last alloc", get_track(s, p, TRACK_ALLOC));
+		print_track("Last free ", get_track(s, p, TRACK_FREE));
+		off += 2 * sizeof(struct track);
+	}
+
+	if (off != s->size)
+		/* Beginning of the filler is the free pointer */
+		print_section("Filler", p + off, s->size - off);
+}
+
+static void object_err(struct kmem_cache *s, struct page *page,
+			u8 *object, char *reason)
+{
+	u8 *addr = page_address(page);
+
+	printk(KERN_ERR "*** SLUB %s: %s@0x%p slab 0x%p\n",
+			s->name, reason, object, page);
+	printk(KERN_ERR "    offset=%tu flags=0x%04lx inuse=%u freelist=0x%p\n",
+		object - addr, page->flags, page->inuse, page->freelist);
+	if (object > addr + 16)
+		print_section("Bytes b4", object - 16, 16);
+	print_section("Object", object, min(s->objsize, 128));
+	print_trailer(s, object);
+	dump_stack();
+}
+
+static void slab_err(struct kmem_cache *s, struct page *page, char *reason, ...)
+{
+	va_list args;
+	char buf[100];
+
+	va_start(args, reason);
+	vsnprintf(buf, sizeof(buf), reason, args);
+	va_end(args);
+	printk(KERN_ERR "*** SLUB %s: %s in slab @0x%p\n", s->name, buf,
+		page);
+	dump_stack();
+}
+
+static void init_object(struct kmem_cache *s, void *object, int active)
+{
+	u8 *p = object;
+
+	if (s->flags & __OBJECT_POISON) {
+		memset(p, POISON_FREE, s->objsize - 1);
+		p[s->objsize -1] = POISON_END;
+	}
+
+	if (s->flags & SLAB_RED_ZONE)
+		memset(p + s->objsize,
+			active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE,
+			s->inuse - s->objsize);
+}
+
+static int check_bytes(u8 *start, unsigned int value, unsigned int bytes)
+{
+	while (bytes) {
+		if (*start != (u8)value)
+			return 0;
+		start++;
+		bytes--;
+	}
+	return 1;
+}
+
+
+static int check_valid_pointer(struct kmem_cache *s, struct page *page,
+					 void *object)
+{
+	void *base;
+
+	if (!object)
+		return 1;
+
+	base = page_address(page);
+	if (object < base || object >= base + s->objects * s->size ||
+		(object - base) % s->size) {
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * Object layout:
+ *
+ * object address
+ * 	Bytes of the object to be managed.
+ * 	If the freepointer may overlay the object then the free
+ * 	pointer is the first word of the object.
+ * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
+ * 	0xa5 (POISON_END)
+ *
+ * object + s->objsize
+ * 	Padding to reach word boundary. This is also used for Redzoning.
+ * 	Padding is extended to word size if Redzoning is enabled
+ * 	and objsize == inuse.
+ * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
+ * 	0xcc (RED_ACTIVE) for objects in use.
+ *
+ * object + s->inuse
+ * 	A. Free pointer (if we cannot overwrite object on free)
+ * 	B. Tracking data for SLAB_STORE_USER
+ * 	C. Padding to reach required alignment boundary
+ * 		Padding is done using 0x5a (POISON_INUSE)
+ *
+ * object + s->size
+ *
+ * If slabcaches are merged then the objsize and inuse boundaries are to
+ * be ignored. And therefore no slab options that rely on these boundaries
+ * may be used with merged slabcaches.
+ */
+
+static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
+						void *from, void *to)
+{
+	printk(KERN_ERR "@@@ SLUB: %s Restoring %s (0x%x) from 0x%p-0x%p\n",
+		s->name, message, data, from, to - 1);
+	memset(from, data, to - from);
+}
+
+static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
+{
+	unsigned long off = s->inuse;	/* The end of info */
+
+	if (s->offset)
+		/* Freepointer is placed after the object. */
+		off += sizeof(void *);
+
+	if (s->flags & SLAB_STORE_USER)
+		/* We also have user information there */
+		off += 2 * sizeof(struct track);
+
+	if (s->size == off)
+		return 1;
+
+	if (check_bytes(p + off, POISON_INUSE, s->size - off))
+		return 1;
+
+	object_err(s, page, p, "Object padding check fails");
+
+	/*
+	 * Restore padding
+	 */
+	restore_bytes(s, "object padding", POISON_INUSE, p + off, p + s->size);
+	return 0;
+}
+
+static int slab_pad_check(struct kmem_cache *s, struct page *page)
+{
+	u8 *p;
+	int length, remainder;
+
+	if (!(s->flags & SLAB_POISON))
+		return 1;
+
+	p = page_address(page);
+	length = s->objects * s->size;
+	remainder = (PAGE_SIZE << s->order) - length;
+	if (!remainder)
+		return 1;
+
+	if (!check_bytes(p + length, POISON_INUSE, remainder)) {
+		printk(KERN_ERR "SLUB: %s slab 0x%p: Padding fails check\n",
+			s->name, p);
+		dump_stack();
+		restore_bytes(s, "slab padding", POISON_INUSE, p + length,
+			p + length + remainder);
+		return 0;
+	}
+	return 1;
+}
+
+static int check_object(struct kmem_cache *s, struct page *page,
+					void *object, int active)
+{
+	u8 *p = object;
+	u8 *endobject = object + s->objsize;
+
+	if (s->flags & SLAB_RED_ZONE) {
+		unsigned int red =
+			active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE;
+
+		if (!check_bytes(endobject, red, s->inuse - s->objsize)) {
+			object_err(s, page, object,
+			active ? "Redzone Active" : "Redzone Inactive");
+			restore_bytes(s, "redzone", red,
+				endobject, object + s->inuse);
+			return 0;
+		}
+	} else {
+		if ((s->flags & SLAB_POISON) && s->objsize < s->inuse &&
+			!check_bytes(endobject, POISON_INUSE,
+					s->inuse - s->objsize)) {
+		object_err(s, page, p, "Alignment padding check fails");
+		/*
+		 * Fix it so that there will not be another report.
+		 *
+		 * Hmmm... We may be corrupting an object that now expects
+		 * to be longer than allowed.
+		 */
+		restore_bytes(s, "alignment padding", POISON_INUSE,
+			endobject, object + s->inuse);
+		}
+	}
+
+	if (s->flags & SLAB_POISON) {
+		if (!active && (s->flags & __OBJECT_POISON) &&
+			(!check_bytes(p, POISON_FREE, s->objsize - 1) ||
+				p[s->objsize - 1] != POISON_END)) {
+
+			object_err(s, page, p, "Poison check failed");
+			restore_bytes(s, "Poison", POISON_FREE,
+						p, p + s->objsize -1);
+			restore_bytes(s, "Poison", POISON_END,
+					p + s->objsize - 1, p + s->objsize);
+			return 0;
+		}
+		/*
+		 * check_pad_bytes cleans up on its own.
+		 */
+		check_pad_bytes(s, page, p);
+	}
+
+	if (!s->offset && active)
+		/*
+		 * Object and freepointer overlap. Cannot check
+		 * freepointer while object is allocated.
+		 */
+		return 1;
+
+	/* Check free pointer validity */
+	if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+		object_err(s, page, p, "Freepointer corrupt");
+		/*
+		 * No choice but to zap it and thus loose the remainder
+		 * of the free objects in this slab. May cause
+		 * another error because the object count maybe
+		 * wrong now.
+		 */
+		set_freepointer(s, p, NULL);
+		return 0;
+	}
+	return 1;
+}
+
+static int check_slab(struct kmem_cache *s, struct page *page)
+{
+	VM_BUG_ON(!irqs_disabled());
+
+	if (!PageSlab(page)) {
+		printk(KERN_ERR "SLUB: %s Not a valid slab page @0x%p "
+			"flags=%lx mapping=0x%p count=%d \n",
+			s->name, page, page->flags, page->mapping,
+			page_count(page));
+		return 0;
+	}
+	if (page->offset * sizeof(void *) != s->offset) {
+		printk(KERN_ERR "SLUB: %s Corrupted offset %lu in slab @0x%p"
+			" flags=0x%lx mapping=0x%p count=%d\n",
+			s->name,
+			(unsigned long)(page->offset * sizeof(void *)),
+			page,
+			page->flags,
+			page->mapping,
+			page_count(page));
+		dump_stack();
+		return 0;
+	}
+	if (page->inuse > s->objects) {
+		printk(KERN_ERR "SLUB: %s Inuse %u > max %u in slab "
+			"page @0x%p flags=%lx mapping=0x%p count=%d\n",
+			s->name, page->inuse, s->objects, page, page->flags,
+			page->mapping, page_count(page));
+		dump_stack();
+		return 0;
+	}
+	/* Slab_pad_check fixes things up after itself */
+	slab_pad_check(s, page);
+	return 1;
+}
+
+/*
+ * Determine if a certain object on a page is on the freelist and
+ * therefore free. Must hold the slab lock for cpu slabs to
+ * guarantee that the chains are consistent.
+ */
+static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
+{
+	int nr = 0;
+	void *fp = page->freelist;
+	void *object = NULL;
+
+	while (fp && nr <= s->objects) {
+		if (fp == search)
+			return 1;
+		if (!check_valid_pointer(s, page, fp)) {
+			if (object) {
+				object_err(s, page, object,
+					"Freechain corrupt");
+				set_freepointer(s, object, NULL);
+				break;
+			} else {
+				printk(KERN_ERR "SLUB: %s slab 0x%p "
+					"freepointer 0x%p corrupted.\n",
+					s->name, page, fp);
+				dump_stack();
+				page->freelist = NULL;
+				page->inuse = s->objects;
+				return 0;
+			}
+			break;
+		}
+		object = fp;
+		fp = get_freepointer(s, object);
+		nr++;
+	}
+
+	if (page->inuse != s->objects - nr) {
+		printk(KERN_ERR "slab %s: page 0x%p wrong object count."
+			" counter is %d but counted were %d\n",
+			s->name, page, page->inuse,
+			s->objects - nr);
+		page->inuse = s->objects - nr;
+	}
+	return search == NULL;
+}
+
+static int alloc_object_checks(struct kmem_cache *s, struct page *page,
+							void *object)
+{
+	if (!check_slab(s, page))
+		goto bad;
+
+	if (object && !on_freelist(s, page, object)) {
+		printk(KERN_ERR "SLUB: %s Object 0x%p@0x%p "
+			"already allocated.\n",
+			s->name, object, page);
+		goto dump;
+	}
+
+	if (!check_valid_pointer(s, page, object)) {
+		object_err(s, page, object, "Freelist Pointer check fails");
+		goto dump;
+	}
+
+	if (!object)
+		return 1;
+
+	if (!check_object(s, page, object, 0))
+		goto bad;
+	init_object(s, object, 1);
+
+	if (s->flags & SLAB_TRACE) {
+		printk(KERN_INFO "TRACE %s alloc 0x%p inuse=%d fp=0x%p\n",
+			s->name, object, page->inuse,
+			page->freelist);
+		dump_stack();
+	}
+	return 1;
+dump:
+	dump_stack();
+bad:
+	if (PageSlab(page)) {
+		/*
+		 * If this is a slab page then lets do the best we can
+		 * to avoid issues in the future. Marking all objects
+		 * as used avoids touching the remainder.
+		 */
+		printk(KERN_ERR "@@@ SLUB: %s slab 0x%p. Marking all objects used.\n",
+			s->name, page);
+		page->inuse = s->objects;
+		page->freelist = NULL;
+		/* Fix up fields that may be corrupted */
+		page->offset = s->offset / sizeof(void *);
+	}
+	return 0;
+}
+
+static int free_object_checks(struct kmem_cache *s, struct page *page,
+							void *object)
+{
+	if (!check_slab(s, page))
+		goto fail;
+
+	if (!check_valid_pointer(s, page, object)) {
+		printk(KERN_ERR "SLUB: %s slab 0x%p invalid "
+			"object pointer 0x%p\n",
+			s->name, page, object);
+		goto fail;
+	}
+
+	if (on_freelist(s, page, object)) {
+		printk(KERN_ERR "SLUB: %s slab 0x%p object "
+			"0x%p already free.\n", s->name, page, object);
+		goto fail;
+	}
+
+	if (!check_object(s, page, object, 1))
+		return 0;
+
+	if (unlikely(s != page->slab)) {
+		if (!PageSlab(page))
+			printk(KERN_ERR "slab_free %s size %d: attempt to"
+				"free object(0x%p) outside of slab.\n",
+				s->name, s->size, object);
+		else
+		if (!page->slab)
+			printk(KERN_ERR
+				"slab_free : no slab(NULL) for object 0x%p.\n",
+						object);
+		else
+		printk(KERN_ERR "slab_free %s(%d): object at 0x%p"
+				" belongs to slab %s(%d)\n",
+				s->name, s->size, object,
+				page->slab->name, page->slab->size);
+		goto fail;
+	}
+	if (s->flags & SLAB_TRACE) {
+		printk(KERN_INFO "TRACE %s free 0x%p inuse=%d fp=0x%p\n",
+			s->name, object, page->inuse,
+			page->freelist);
+		print_section("Object", object, s->objsize);
+		dump_stack();
+	}
+	init_object(s, object, 0);
+	return 1;
+fail:
+	dump_stack();
+	printk(KERN_ERR "@@@ SLUB: %s slab 0x%p object at 0x%p not freed.\n",
+		s->name, page, object);
+	return 0;
+}
+
+/*
+ * Slab allocation and freeing
+ */
+static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
+{
+	struct page * page;
+	int pages = 1 << s->order;
+
+	if (s->order)
+		flags |= __GFP_COMP;
+
+	if (s->flags & SLAB_CACHE_DMA)
+		flags |= SLUB_DMA;
+
+	if (node == -1)
+		page = alloc_pages(flags, s->order);
+	else
+		page = alloc_pages_node(node, flags, s->order);
+
+	if (!page)
+		return NULL;
+
+	mod_zone_page_state(page_zone(page),
+		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
+		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
+		pages);
+
+	return page;
+}
+
+static void setup_object(struct kmem_cache *s, struct page *page,
+				void *object)
+{
+	if (PageError(page)) {
+		init_object(s, object, 0);
+		init_tracking(s, object);
+	}
+
+	if (unlikely(s->ctor)) {
+		int mode = SLAB_CTOR_CONSTRUCTOR;
+
+		if (!(s->flags & __GFP_WAIT))
+			mode |= SLAB_CTOR_ATOMIC;
+
+		s->ctor(object, s, mode);
+	}
+}
+
+static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
+{
+	struct page *page;
+	struct kmem_cache_node *n;
+	void *start;
+	void *end;
+	void *last;
+	void *p;
+
+	if (flags & __GFP_NO_GROW)
+		return NULL;
+
+	BUG_ON(flags & ~(GFP_DMA | GFP_LEVEL_MASK));
+
+	if (flags & __GFP_WAIT)
+		local_irq_enable();
+
+	page = allocate_slab(s, flags & GFP_LEVEL_MASK, node);
+	if (!page)
+		goto out;
+
+	n = get_node(s, page_to_nid(page));
+	if (n)
+		atomic_long_inc(&n->nr_slabs);
+	page->offset = s->offset / sizeof(void *);
+	page->slab = s;
+	page->flags |= 1 << PG_slab;
+	if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
+			SLAB_STORE_USER | SLAB_TRACE))
+		page->flags |= 1 << PG_error;
+
+	start = page_address(page);
+	end = start + s->objects * s->size;
+
+	if (unlikely(s->flags & SLAB_POISON))
+		memset(start, POISON_INUSE, PAGE_SIZE << s->order);
+
+	last = start;
+	for (p = start + s->size; p < end; p += s->size) {
+		setup_object(s, page, last);
+		set_freepointer(s, last, p);
+		last = p;
+	}
+	setup_object(s, page, last);
+	set_freepointer(s, last, NULL);
+
+	page->freelist = start;
+	page->inuse = 0;
+out:
+	if (flags & __GFP_WAIT)
+		local_irq_disable();
+	return page;
+}
+
+static void __free_slab(struct kmem_cache *s, struct page *page)
+{
+	int pages = 1 << s->order;
+
+	if (unlikely(PageError(page) || s->dtor)) {
+		void *start = page_address(page);
+		void *end = start + (pages << PAGE_SHIFT);
+		void *p;
+
+		slab_pad_check(s, page);
+		for (p = start; p <= end - s->size; p += s->size) {
+			if (s->dtor)
+				s->dtor(p, s, 0);
+			check_object(s, page, p, 0);
+		}
+	}
+
+	mod_zone_page_state(page_zone(page),
+		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
+		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
+		- pages);
+
+	page->mapping = NULL;
+	__free_pages(page, s->order);
+}
+
+static void rcu_free_slab(struct rcu_head *h)
+{
+	struct page *page;
+
+	page = container_of((struct list_head *)h, struct page, lru);
+	__free_slab(page->slab, page);
+}
+
+static void free_slab(struct kmem_cache *s, struct page *page)
+{
+	if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
+		/*
+		 * RCU free overloads the RCU head over the LRU
+		 */
+		struct rcu_head *head = (void *)&page->lru;
+
+		call_rcu(head, rcu_free_slab);
+	} else
+		__free_slab(s, page);
+}
+
+static void discard_slab(struct kmem_cache *s, struct page *page)
+{
+	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+	atomic_long_dec(&n->nr_slabs);
+	reset_page_mapcount(page);
+	page->flags &= ~(1 << PG_slab | 1 << PG_error);
+	free_slab(s, page);
+}
+
+/*
+ * Per slab locking using the pagelock
+ */
+static __always_inline void slab_lock(struct page *page)
+{
+	bit_spin_lock(PG_locked, &page->flags);
+}
+
+static __always_inline void slab_unlock(struct page *page)
+{
+	bit_spin_unlock(PG_locked, &page->flags);
+}
+
+static __always_inline int slab_trylock(struct page *page)
+{
+	int rc = 1;
+
+	rc = bit_spin_trylock(PG_locked, &page->flags);
+	return rc;
+}
+
+/*
+ * Management of partially allocated slabs
+ */
+static void add_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);
+	n->nr_partial++;
+	list_add(&page->lru, &n->partial);
+	spin_unlock(&n->list_lock);
+}
+
+static void remove_partial(struct kmem_cache *s,
+						struct page *page)
+{
+	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+	spin_lock(&n->list_lock);
+	list_del(&page->lru);
+	n->nr_partial--;
+	spin_unlock(&n->list_lock);
+}
+
+/*
+ * Lock page and remove it from the partial list
+ *
+ * Must hold list_lock
+ */
+static int lock_and_del_slab(struct kmem_cache_node *n, struct page *page)
+{
+	if (slab_trylock(page)) {
+		list_del(&page->lru);
+		n->nr_partial--;
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Try to get a partial slab from a specific node
+ */
+static struct page *get_partial_node(struct kmem_cache_node *n)
+{
+	struct page *page;
+
+	/*
+	 * Racy check. If we mistakenly see no partial slabs then we
+	 * just allocate an empty slab. If we mistakenly try to get a
+	 * partial slab then get_partials() will return NULL.
+	 */
+	if (!n || !n->nr_partial)
+		return NULL;
+
+	spin_lock(&n->list_lock);
+	list_for_each_entry(page, &n->partial, lru)
+		if (lock_and_del_slab(n, page))
+			goto out;
+	page = NULL;
+out:
+	spin_unlock(&n->list_lock);
+	return page;
+}
+
+/*
+ * Get a page from somewhere. Search in increasing NUMA
+ * distances.
+ */
+static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
+{
+#ifdef CONFIG_NUMA
+	struct zonelist *zonelist;
+	struct zone **z;
+	struct page *page;
+
+	/*
+	 * The defrag ratio allows to configure the tradeoffs between
+	 * inter node defragmentation and node local allocations.
+	 * A lower defrag_ratio increases the tendency to do local
+	 * allocations instead of scanning throught the partial
+	 * lists on other nodes.
+	 *
+	 * If defrag_ratio is set to 0 then kmalloc() always
+	 * returns node local objects. If its higher then kmalloc()
+	 * may return off node objects in order to avoid fragmentation.
+	 *
+	 * A higher ratio means slabs may be taken from other nodes
+	 * thus reducing the number of partial slabs on those nodes.
+	 *
+	 * If /sys/slab/xx/defrag_ratio is set to 100 (which makes
+	 * defrag_ratio = 1000) then every (well almost) allocation
+	 * will first attempt to defrag slab caches on other nodes. This
+	 * means scanning over all nodes to look for partial slabs which
+	 * may be a bit expensive to do on every slab allocation.
+	 */
+	if (!s->defrag_ratio || get_cycles() % 1024 > s->defrag_ratio)
+		return NULL;
+
+	zonelist = &NODE_DATA(slab_node(current->mempolicy))
+					->node_zonelists[gfp_zone(flags)];
+	for (z = zonelist->zones; *z; z++) {
+		struct kmem_cache_node *n;
+
+		n = get_node(s, zone_to_nid(*z));
+
+		if (n && cpuset_zone_allowed_hardwall(*z, flags) &&
+				n->nr_partial > 2) {
+			page = get_partial_node(n);
+			if (page)
+				return page;
+		}
+	}
+#endif
+	return NULL;
+}
+
+/*
+ * Get a partial page, lock it and return it.
+ */
+static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
+{
+	struct page *page;
+	int searchnode = (node == -1) ? numa_node_id() : node;
+
+	page = get_partial_node(get_node(s, searchnode));
+	if (page || (flags & __GFP_THISNODE))
+		return page;
+
+	return get_any_partial(s, flags);
+}
+
+/*
+ * Move a page back to the lists.
+ *
+ * Must be called with the slab lock held.
+ *
+ * On exit the slab lock will have been dropped.
+ */
+static void putback_slab(struct kmem_cache *s, struct page *page)
+{
+	if (page->inuse) {
+		if (page->freelist)
+			add_partial(s, page);
+		slab_unlock(page);
+	} else {
+		slab_unlock(page);
+		discard_slab(s, page);
+	}
+}
+
+/*
+ * Remove the cpu slab
+ */
+static void deactivate_slab(struct kmem_cache *s, struct page *page, int cpu)
+{
+	s->cpu_slab[cpu] = NULL;
+	ClearPageActive(page);
+
+	putback_slab(s, page);
+}
+
+static void flush_slab(struct kmem_cache *s, struct page *page, int cpu)
+{
+	slab_lock(page);
+	deactivate_slab(s, page, cpu);
+}
+
+/*
+ * Flush cpu slab.
+ * Called from IPI handler with interrupts disabled.
+ */
+static void __flush_cpu_slab(struct kmem_cache *s, int cpu)
+{
+	struct page *page = s->cpu_slab[cpu];
+
+	if (likely(page))
+		flush_slab(s, page, cpu);
+}
+
+static void flush_cpu_slab(void *d)
+{
+	struct kmem_cache *s = d;
+	int cpu = smp_processor_id();
+
+	__flush_cpu_slab(s, cpu);
+}
+
+static void flush_all(struct kmem_cache *s)
+{
+#ifdef CONFIG_SMP
+	on_each_cpu(flush_cpu_slab, s, 1, 1);
+#else
+	unsigned long flags;
+
+	local_irq_save(flags);
+	flush_cpu_slab(s);
+	local_irq_restore(flags);
+#endif
+}
+
+/*
+ * slab_alloc is optimized to only modify two cachelines on the fast path
+ * (aside from the stack):
+ *
+ * 1. The page struct
+ * 2. The first cacheline of the object to be allocated.
+ *
+ * The only cache lines that are read (apart from code) is the
+ * per cpu array in the kmem_cache struct.
+ *
+ * Fastpath is not possible if we need to get a new slab or have
+ * debugging enabled (which means all slabs are marked with PageError)
+ */
+static __always_inline void *slab_alloc(struct kmem_cache *s,
+					gfp_t gfpflags, int node)
+{
+	struct page *page;
+	void **object;
+	unsigned long flags;
+	int cpu;
+
+	local_irq_save(flags);
+	cpu = smp_processor_id();
+	page = s->cpu_slab[cpu];
+	if (!page)
+		goto new_slab;
+
+	slab_lock(page);
+	if (unlikely(node != -1 && page_to_nid(page) != node))
+		goto another_slab;
+redo:
+	object = page->freelist;
+	if (unlikely(!object))
+		goto another_slab;
+	if (unlikely(PageError(page)))
+		goto debug;
+
+have_object:
+	page->inuse++;
+	page->freelist = object[page->offset];
+	slab_unlock(page);
+	local_irq_restore(flags);
+	return object;
+
+another_slab:
+	deactivate_slab(s, page, cpu);
+
+new_slab:
+	page = get_partial(s, gfpflags, node);
+	if (likely(page)) {
+have_slab:
+		s->cpu_slab[cpu] = page;
+		SetPageActive(page);
+		goto redo;
+	}
+
+	page = new_slab(s, gfpflags, node);
+	if (page) {
+		cpu = smp_processor_id();
+		if (s->cpu_slab[cpu]) {
+			/*
+			 * Someone else populated the cpu_slab while we enabled
+			 * interrupts, or we have got scheduled on another cpu.
+			 * The page may not be on the requested node.
+			 */
+			if (node == -1 ||
+				page_to_nid(s->cpu_slab[cpu]) == node) {
+				/*
+				 * Current cpuslab is acceptable and we
+				 * want the current one since its cache hot
+				 */
+				discard_slab(s, page);
+				page = s->cpu_slab[cpu];
+				slab_lock(page);
+				goto redo;
+			}
+			/* Dump the current slab */
+			flush_slab(s, s->cpu_slab[cpu], cpu);
+		}
+		slab_lock(page);
+		goto have_slab;
+	}
+	local_irq_restore(flags);
+	return NULL;
+debug:
+	if (!alloc_object_checks(s, page, object))
+		goto another_slab;
+	if (s->flags & SLAB_STORE_USER)
+		set_tracking(s, object, TRACK_ALLOC);
+	goto have_object;
+}
+
+void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
+{
+	return slab_alloc(s, gfpflags, -1);
+}
+EXPORT_SYMBOL(kmem_cache_alloc);
+
+#ifdef CONFIG_NUMA
+void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
+{
+	return slab_alloc(s, gfpflags, node);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_node);
+#endif
+
+/*
+ * The fastpath only writes the cacheline of the page struct and the first
+ * cacheline of the object.
+ *
+ * No special cachelines need to be read
+ */
+static void slab_free(struct kmem_cache *s, struct page *page, void *x)
+{
+	void *prior;
+	void **object = (void *)x;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	slab_lock(page);
+
+	if (unlikely(PageError(page)))
+		goto debug;
+checks_ok:
+	prior = object[page->offset] = page->freelist;
+	page->freelist = object;
+	page->inuse--;
+
+	if (unlikely(PageActive(page)))
+		/*
+		 * Cpu slabs are never on partial lists and are
+		 * never freed.
+		 */
+		goto out_unlock;
+
+	if (unlikely(!page->inuse))
+		goto slab_empty;
+
+	/*
+	 * Objects left in the slab. If it
+	 * was not on the partial list before
+	 * then add it.
+	 */
+	if (unlikely(!prior))
+		add_partial(s, page);
+
+out_unlock:
+	slab_unlock(page);
+	local_irq_restore(flags);
+	return;
+
+slab_empty:
+	if (prior)
+		/*
+		 * Partially used slab that is on the partial list.
+		 */
+		remove_partial(s, page);
+
+	slab_unlock(page);
+	discard_slab(s, page);
+	local_irq_restore(flags);
+	return;
+
+debug:
+	if (free_object_checks(s, page, x))
+		goto checks_ok;
+	goto out_unlock;
+}
+
+void kmem_cache_free(struct kmem_cache *s, void *x)
+{
+	struct page * page;
+
+	page = virt_to_page(x);
+
+	if (unlikely(PageCompound(page)))
+		page = page->first_page;
+
+
+	if (unlikely(PageError(page) && (s->flags & SLAB_STORE_USER)))
+		set_tracking(s, x, TRACK_FREE);
+	slab_free(s, page, x);
+}
+EXPORT_SYMBOL(kmem_cache_free);
+
+/* Figure out on which slab object the object resides */
+static struct page *get_object_page(const void *x)
+{
+	struct page *page = virt_to_page(x);
+
+	if (unlikely(PageCompound(page)))
+		page = page->first_page;
+
+	if (!PageSlab(page))
+		return NULL;
+
+	return page;
+}
+
+/*
+ * kmem_cache_open produces objects aligned at "size" and the first object
+ * is placed at offset 0 in the slab (We have no metainformation on the
+ * slab, all slabs are in essence "off slab").
+ *
+ * In order to get the desired alignment one just needs to align the
+ * size.
+ *
+ * Notice that the allocation order determines the sizes of the per cpu
+ * caches. Each processor has always one slab available for allocations.
+ * Increasing the allocation order reduces the number of times that slabs
+ * must be moved on and off the partial lists and therefore may influence
+ * locking overhead.
+ *
+ * The offset is used to relocate the free list link in each object. It is
+ * therefore possible to move the free list link behind the object. This
+ * is necessary for RCU to work properly and also useful for debugging.
+ */
+
+/*
+ * Mininum / Maximum order of slab pages. This influences locking overhead
+ * and slab fragmentation. A higher order reduces the number of partial slabs
+ * and increases the number of allocations possible without having to
+ * take the list_lock.
+ */
+static int slub_min_order;
+static int slub_max_order = DEFAULT_MAX_ORDER;
+
+/*
+ * Minimum number of objects per slab. This is necessary in order to
+ * reduce locking overhead. Similar to the queue size in SLAB.
+ */
+static int slub_min_objects = DEFAULT_MIN_OBJECTS;
+
+/*
+ * Merge control. If this is set then no merging of slab caches will occur.
+ */
+static int slub_nomerge;
+
+/*
+ * Debug settings:
+ */
+static int slub_debug;
+
+static char *slub_debug_slabs;
+
+/*
+ * Calculate the order of allocation given an slab object size.
+ *
+ * The order of allocation has significant impact on other elements
+ * of the system. Generally order 0 allocations should be preferred
+ * since they do not cause fragmentation in the page allocator. Larger
+ * objects may have problems with order 0 because there may be too much
+ * space left unused in a slab. We go to a higher order if more than 1/8th
+ * of the slab would be wasted.
+ *
+ * In order to reach satisfactory performance we must ensure that
+ * a minimum number of objects is in one slab. Otherwise we may
+ * generate too much activity on the partial lists. This is less a
+ * concern for large slabs though. slub_max_order specifies the order
+ * where we begin to stop considering the number of objects in a slab.
+ *
+ * Higher order allocations also allow the placement of more objects
+ * in a slab and thereby reduce object handling overhead. If the user
+ * has requested a higher mininum order then we start with that one
+ * instead of zero.
+ */
+static int calculate_order(int size)
+{
+	int order;
+	int rem;
+
+	for (order = max(slub_min_order, fls(size - 1) - PAGE_SHIFT);
+			order < MAX_ORDER; order++) {
+		unsigned long slab_size = PAGE_SIZE << order;
+
+		if (slub_max_order > order &&
+				slab_size < slub_min_objects * size)
+			continue;
+
+		if (slab_size < size)
+			continue;
+
+		rem = slab_size % size;
+
+		if (rem <= (PAGE_SIZE << order) / 8)
+			break;
+
+	}
+	if (order >= MAX_ORDER)
+		return -E2BIG;
+	return order;
+}
+
+/*
+ * Function to figure out which alignment to use from the
+ * various ways of specifying it.
+ */
+static unsigned long calculate_alignment(unsigned long flags,
+		unsigned long align, unsigned long size)
+{
+	/*
+	 * If the user wants hardware cache aligned objects then
+	 * follow that suggestion if the object is sufficiently
+	 * large.
+	 *
+	 * The hardware cache alignment cannot override the
+	 * specified alignment though. If that is greater
+	 * then use it.
+	 */
+	if ((flags & (SLAB_MUST_HWCACHE_ALIGN | SLAB_HWCACHE_ALIGN)) &&
+			size > L1_CACHE_BYTES / 2)
+		return max_t(unsigned long, align, L1_CACHE_BYTES);
+
+	if (align < ARCH_SLAB_MINALIGN)
+		return ARCH_SLAB_MINALIGN;
+
+	return ALIGN(align, sizeof(void *));
+}
+
+static void init_kmem_cache_node(struct kmem_cache_node *n)
+{
+	n->nr_partial = 0;
+	atomic_long_set(&n->nr_slabs, 0);
+	spin_lock_init(&n->list_lock);
+	INIT_LIST_HEAD(&n->partial);
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * No kmalloc_node yet so do it by hand. We know that this is the first
+ * slab on the node for this slabcache. There are no concurrent accesses
+ * possible.
+ *
+ * Note that this function only works on the kmalloc_node_cache
+ * when allocating for the kmalloc_node_cache.
+ */
+static struct kmem_cache_node * __init early_kmem_cache_node_alloc(gfp_t gfpflags,
+								int node)
+{
+	struct page *page;
+	struct kmem_cache_node *n;
+
+	BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
+
+	page = new_slab(kmalloc_caches, gfpflags | GFP_THISNODE, node);
+	/* new_slab() disables interupts */
+	local_irq_enable();
+
+	BUG_ON(!page);
+	n = page->freelist;
+	BUG_ON(!n);
+	page->freelist = get_freepointer(kmalloc_caches, n);
+	page->inuse++;
+	kmalloc_caches->node[node] = n;
+	init_object(kmalloc_caches, n, 1);
+	init_kmem_cache_node(n);
+	atomic_long_inc(&n->nr_slabs);
+	add_partial(kmalloc_caches, page);
+	return n;
+}
+
+static void free_kmem_cache_nodes(struct kmem_cache *s)
+{
+	int node;
+
+	for_each_online_node(node) {
+		struct kmem_cache_node *n = s->node[node];
+		if (n && n != &s->local_node)
+			kmem_cache_free(kmalloc_caches, n);
+		s->node[node] = NULL;
+	}
+}
+
+static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
+{
+	int node;
+	int local_node;
+
+	if (slab_state >= UP)
+		local_node = page_to_nid(virt_to_page(s));
+	else
+		local_node = 0;
+
+	for_each_online_node(node) {
+		struct kmem_cache_node *n;
+
+		if (local_node == node)
+			n = &s->local_node;
+		else {
+			if (slab_state == DOWN) {
+				n = early_kmem_cache_node_alloc(gfpflags,
+								node);
+				continue;
+			}
+			n = kmem_cache_alloc_node(kmalloc_caches,
+							gfpflags, node);
+
+			if (!n) {
+				free_kmem_cache_nodes(s);
+				return 0;
+			}
+
+		}
+		s->node[node] = n;
+		init_kmem_cache_node(n);
+	}
+	return 1;
+}
+#else
+static void free_kmem_cache_nodes(struct kmem_cache *s)
+{
+}
+
+static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
+{
+	init_kmem_cache_node(&s->local_node);
+	return 1;
+}
+#endif
+
+/*
+ * calculate_sizes() determines the order and the distribution of data within
+ * a slab object.
+ */
+static int calculate_sizes(struct kmem_cache *s)
+{
+	unsigned long flags = s->flags;
+	unsigned long size = s->objsize;
+	unsigned long align = s->align;
+
+	/*
+	 * Determine if we can poison the object itself. If the user of
+	 * the slab may touch the object after free or before allocation
+	 * then we should never poison the object itself.
+	 */
+	if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
+			!s->ctor && !s->dtor)
+		s->flags |= __OBJECT_POISON;
+	else
+		s->flags &= ~__OBJECT_POISON;
+
+	/*
+	 * Round up object size to the next word boundary. We can only
+	 * place the free pointer at word boundaries and this determines
+	 * the possible location of the free pointer.
+	 */
+	size = ALIGN(size, sizeof(void *));
+
+	/*
+	 * If we are redzoning then check if there is some space between the
+	 * end of the object and the free pointer. If not then add an
+	 * additional word, so that we can establish a redzone between
+	 * the object and the freepointer to be able to check for overwrites.
+	 */
+	if ((flags & SLAB_RED_ZONE) && size == s->objsize)
+		size += sizeof(void *);
+
+	/*
+	 * With that we have determined how much of the slab is in actual
+	 * use by the object. This is the potential offset to the free
+	 * pointer.
+	 */
+	s->inuse = size;
+
+	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
+		s->ctor || s->dtor)) {
+		/*
+		 * Relocate free pointer after the object if it is not
+		 * permitted to overwrite the first word of the object on
+		 * kmem_cache_free.
+		 *
+		 * This is the case if we do RCU, have a constructor or
+		 * destructor or are poisoning the objects.
+		 */
+		s->offset = size;
+		size += sizeof(void *);
+	}
+
+	if (flags & SLAB_STORE_USER)
+		/*
+		 * Need to store information about allocs and frees after
+		 * the object.
+		 */
+		size += 2 * sizeof(struct track);
+
+	if (flags & DEBUG_DEFAULT_FLAGS)
+		/*
+		 * Add some empty padding so that we can catch
+		 * overwrites from earlier objects rather than let
+		 * tracking information or the free pointer be
+		 * corrupted if an user writes before the start
+		 * of the object.
+		 */
+		size += sizeof(void *);
+	/*
+	 * Determine the alignment based on various parameters that the
+	 * user specified (this is unecessarily complex due to the attempt
+	 * to be compatible with SLAB. Should be cleaned up some day).
+	 */
+	align = calculate_alignment(flags, align, s->objsize);
+
+	/*
+	 * SLUB stores one object immediately after another beginning from
+	 * offset 0. In order to align the objects we have to simply size
+	 * each object to conform to the alignment.
+	 */
+	size = ALIGN(size, align);
+	s->size = size;
+
+	s->order = calculate_order(size);
+	if (s->order < 0)
+		return 0;
+
+	/*
+	 * Determine the number of objects per slab
+	 */
+	s->objects = (PAGE_SIZE << s->order) / size;
+
+	/*
+	 * Verify that the number of objects is within permitted limits.
+	 * The page->inuse field is only 16 bit wide! So we cannot have
+	 * more than 64k objects per slab.
+	 */
+	if (!s->objects || s->objects > 65535)
+		return 0;
+	return 1;
+
+}
+
+static int __init finish_bootstrap(void)
+{
+	struct list_head *h;
+	int err;
+
+	slab_state = SYSFS;
+
+	list_for_each(h, &slab_caches) {
+		struct kmem_cache *s =
+			container_of(h, struct kmem_cache, list);
+
+		err = sysfs_slab_add(s);
+		BUG_ON(err);
+	}
+	return 0;
+}
+
+static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
+		const char *name, size_t size,
+		size_t align, unsigned long flags,
+		void (*ctor)(void *, struct kmem_cache *, unsigned long),
+		void (*dtor)(void *, struct kmem_cache *, unsigned long))
+{
+	memset(s, 0, kmem_size);
+	s->name = name;
+	s->ctor = ctor;
+	s->dtor = dtor;
+	s->objsize = size;
+	s->flags = flags;
+	s->align = align;
+
+	BUG_ON(flags & SLUB_UNIMPLEMENTED);
+
+	/*
+	 * The page->offset field is only 16 bit wide. This is an offset
+	 * in units of words from the beginning of an object. If the slab
+	 * size is bigger then we cannot move the free pointer behind the
+	 * object anymore.
+	 *
+	 * On 32 bit platforms the limit is 256k. On 64bit platforms
+	 * the limit is 512k.
+	 *
+	 * Debugging or ctor/dtors may create a need to move the free
+	 * pointer. Fail if this happens.
+	 */
+	if (s->size >= 65535 * sizeof(void *)) {
+		BUG_ON(flags & (SLAB_RED_ZONE | SLAB_POISON |
+				SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));
+		BUG_ON(ctor || dtor);
+	}
+	else
+		/*
+		 * Enable debugging if selected on the kernel commandline.
+		 */
+		if (slub_debug && (!slub_debug_slabs ||
+		    strncmp(slub_debug_slabs, name,
+		    	strlen(slub_debug_slabs)) == 0))
+				s->flags |= slub_debug;
+
+	if (!calculate_sizes(s))
+		goto error;
+
+	s->refcount = 1;
+#ifdef CONFIG_NUMA
+	s->defrag_ratio = 100;
+#endif
+
+	if (init_kmem_cache_nodes(s, gfpflags & ~SLUB_DMA))
+		return 1;
+error:
+	if (flags & SLAB_PANIC)
+		panic("Cannot create slab %s size=%lu realsize=%u "
+			"order=%u offset=%u flags=%lx\n",
+			s->name, (unsigned long)size, s->size, s->order,
+			s->offset, flags);
+	return 0;
+}
+EXPORT_SYMBOL(kmem_cache_open);
+
+/*
+ * Check if a given pointer is valid
+ */
+int kmem_ptr_validate(struct kmem_cache *s, const void *object)
+{
+	struct page * page;
+	void *addr;
+
+	page = get_object_page(object);
+
+	if (!page || s != page->slab)
+		/* No slab or wrong slab */
+		return 0;
+
+	addr = page_address(page);
+	if (object < addr || object >= addr + s->objects * s->size)
+		/* Out of bounds */
+		return 0;
+
+	if ((object - addr) % s->size)
+		/* Improperly aligned */
+		return 0;
+
+	/*
+	 * We could also check if the object is on the slabs freelist.
+	 * But this would be too expensive and it seems that the main
+	 * purpose of kmem_ptr_valid is to check if the object belongs
+	 * to a certain slab.
+	 */
+	return 1;
+}
+EXPORT_SYMBOL(kmem_ptr_validate);
+
+/*
+ * Determine the size of a slab object
+ */
+unsigned int kmem_cache_size(struct kmem_cache *s)
+{
+	return s->objsize;
+}
+EXPORT_SYMBOL(kmem_cache_size);
+
+const char *kmem_cache_name(struct kmem_cache *s)
+{
+	return s->name;
+}
+EXPORT_SYMBOL(kmem_cache_name);
+
+/*
+ * Attempt to free all slabs on a node
+ */
+static int free_list(struct kmem_cache *s, struct kmem_cache_node *n,
+			struct list_head *list)
+{
+	int slabs_inuse = 0;
+	unsigned long flags;
+	struct page *page, *h;
+
+	spin_lock_irqsave(&n->list_lock, flags);
+	list_for_each_entry_safe(page, h, list, lru)
+		if (!page->inuse) {
+			list_del(&page->lru);
+			discard_slab(s, page);
+		} else
+			slabs_inuse++;
+	spin_unlock_irqrestore(&n->list_lock, flags);
+	return slabs_inuse;
+}
+
+/*
+ * Release all resources used by slab cache
+ */
+static int kmem_cache_close(struct kmem_cache *s)
+{
+	int node;
+
+	flush_all(s);
+
+	/* Attempt to free all objects */
+	for_each_online_node(node) {
+		struct kmem_cache_node *n = get_node(s, node);
+
+		free_list(s, n, &n->partial);
+		if (atomic_long_read(&n->nr_slabs))
+			return 1;
+	}
+	free_kmem_cache_nodes(s);
+	return 0;
+}
+
+/*
+ * Close a cache and release the kmem_cache structure
+ * (must be used for caches created using kmem_cache_create)
+ */
+void kmem_cache_destroy(struct kmem_cache *s)
+{
+	down_write(&slub_lock);
+	s->refcount--;
+	if (!s->refcount) {
+		list_del(&s->list);
+		if (kmem_cache_close(s))
+			WARN_ON(1);
+		sysfs_slab_remove(s);
+		kfree(s);
+	}
+	up_write(&slub_lock);
+}
+EXPORT_SYMBOL(kmem_cache_destroy);
+
+/********************************************************************
+ *		Kmalloc subsystem
+ *******************************************************************/
+
+struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1] __cacheline_aligned;
+EXPORT_SYMBOL(kmalloc_caches);
+
+#ifdef CONFIG_ZONE_DMA
+static struct kmem_cache *kmalloc_caches_dma[KMALLOC_SHIFT_HIGH + 1];
+#endif
+
+static int __init setup_slub_min_order(char *str)
+{
+	get_option (&str, &slub_min_order);
+
+	return 1;
+}
+
+__setup("slub_min_order=", setup_slub_min_order);
+
+static int __init setup_slub_max_order(char *str)
+{
+	get_option (&str, &slub_max_order);
+
+	return 1;
+}
+
+__setup("slub_max_order=", setup_slub_max_order);
+
+static int __init setup_slub_min_objects(char *str)
+{
+	get_option (&str, &slub_min_objects);
+
+	return 1;
+}
+
+__setup("slub_min_objects=", setup_slub_min_objects);
+
+static int __init setup_slub_nomerge(char *str)
+{
+	slub_nomerge = 1;
+	return 1;
+}
+
+__setup("slub_nomerge", setup_slub_nomerge);
+
+static int __init setup_slub_debug(char *str)
+{
+	if (!str || *str != '=')
+		slub_debug = DEBUG_DEFAULT_FLAGS;
+	else {
+		str++;
+		if (*str == 0 || *str == ',')
+			slub_debug = DEBUG_DEFAULT_FLAGS;
+		else
+		for( ;*str && *str != ','; str++)
+			switch (*str) {
+			case 'f' : case 'F' :
+				slub_debug |= SLAB_DEBUG_FREE;
+				break;
+			case 'z' : case 'Z' :
+				slub_debug |= SLAB_RED_ZONE;
+				break;
+			case 'p' : case 'P' :
+				slub_debug |= SLAB_POISON;
+				break;
+			case 'u' : case 'U' :
+				slub_debug |= SLAB_STORE_USER;
+				break;
+			case 't' : case 'T' :
+				slub_debug |= SLAB_TRACE;
+				break;
+			default:
+				printk(KERN_ERR "slub_debug option '%c' "
+					"unknown. skipped\n",*str);
+			}
+	}
+
+	if (*str == ',')
+		slub_debug_slabs = str + 1;
+	return 1;
+}
+
+__setup("slub_debug", setup_slub_debug);
+
+static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,
+		const char *name, int size, gfp_t gfp_flags)
+{
+	unsigned int flags = 0;
+
+	if (gfp_flags & SLUB_DMA)
+		flags = SLAB_CACHE_DMA;
+
+	down_write(&slub_lock);
+	if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
+			flags, NULL, NULL))
+		goto panic;
+
+	list_add(&s->list, &slab_caches);
+	up_write(&slub_lock);
+	if (sysfs_slab_add(s))
+		goto panic;
+	return s;
+
+panic:
+	panic("Creation of kmalloc slab %s size=%d failed.\n", name, size);
+}
+
+static struct kmem_cache *get_slab(size_t size, gfp_t flags)
+{
+	int index = kmalloc_index(size);
+
+	if (!size)
+		return NULL;
+
+	/* Allocation too large? */
+	BUG_ON(index < 0);
+
+#ifdef CONFIG_ZONE_DMA
+	if ((flags & SLUB_DMA)) {
+		struct kmem_cache *s;
+		struct kmem_cache *x;
+		char *text;
+		size_t realsize;
+
+		s = kmalloc_caches_dma[index];
+		if (s)
+			return s;
+
+		/* Dynamically create dma cache */
+		x = kmalloc(kmem_size, flags & ~SLUB_DMA);
+		if (!x)
+			panic("Unable to allocate memory for dma cache\n");
+
+		if (index <= KMALLOC_SHIFT_HIGH)
+			realsize = 1 << index;
+		else {
+			if (index == 1)
+				realsize = 96;
+			else
+				realsize = 192;
+		}
+
+		text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
+				(unsigned int)realsize);
+		s = create_kmalloc_cache(x, text, realsize, flags);
+		kmalloc_caches_dma[index] = s;
+		return s;
+	}
+#endif
+	return &kmalloc_caches[index];
+}
+
+void *__kmalloc(size_t size, gfp_t flags)
+{
+	struct kmem_cache *s = get_slab(size, flags);
+
+	if (s)
+		return kmem_cache_alloc(s, flags);
+	return NULL;
+}
+EXPORT_SYMBOL(__kmalloc);
+
+#ifdef CONFIG_NUMA
+void *__kmalloc_node(size_t size, gfp_t flags, int node)
+{
+	struct kmem_cache *s = get_slab(size, flags);
+
+	if (s)
+		return kmem_cache_alloc_node(s, flags, node);
+	return NULL;
+}
+EXPORT_SYMBOL(__kmalloc_node);
+#endif
+
+size_t ksize(const void *object)
+{
+	struct page *page = get_object_page(object);
+	struct kmem_cache *s;
+
+	BUG_ON(!page);
+	s = page->slab;
+	BUG_ON(!s);
+
+	/*
+	 * Debugging requires use of the padding between object
+	 * and whatever may come after it.
+	 */
+	if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
+		return s->objsize;
+
+	/*
+	 * If we have the need to store the freelist pointer
+	 * back there or track user information then we can
+	 * only use the space before that information.
+	 */
+	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
+		return s->inuse;
+
+	/*
+	 * Else we can use all the padding etc for the allocation
+	 */
+	return s->size;
+}
+EXPORT_SYMBOL(ksize);
+
+void kfree(const void *x)
+{
+	struct kmem_cache *s;
+	struct page *page;
+
+	if (!x)
+		return;
+
+	page = virt_to_page(x);
+
+	if (unlikely(PageCompound(page)))
+		page = page->first_page;
+
+	s = page->slab;
+
+	if (unlikely(PageError(page) && (s->flags & SLAB_STORE_USER)))
+		set_tracking(s, (void *)x, TRACK_FREE);
+	slab_free(s, page, (void *)x);
+}
+EXPORT_SYMBOL(kfree);
+
+/**
+ * krealloc - reallocate memory. The contents will remain unchanged.
+ *
+ * @p: object to reallocate memory for.
+ * @new_size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate.
+ *
+ * The contents of the object pointed to are preserved up to the
+ * lesser of the new and old sizes.  If @p is %NULL, krealloc()
+ * behaves exactly like kmalloc().  If @size is 0 and @p is not a
+ * %NULL pointer, the object pointed to is freed.
+ */
+void *krealloc(const void *p, size_t new_size, gfp_t flags)
+{
+	struct kmem_cache *new_cache;
+	void *ret;
+	struct page *page;
+
+	if (unlikely(!p))
+		return kmalloc(new_size, flags);
+
+	if (unlikely(!new_size)) {
+		kfree(p);
+		return NULL;
+	}
+
+	page = virt_to_page(p);
+
+	if (unlikely(PageCompound(page)))
+		page = page->first_page;
+
+	new_cache = get_slab(new_size, flags);
+
+	/*
+ 	 * If new size fits in the current cache, bail out.
+ 	 */
+	if (likely(page->slab == new_cache))
+		return (void *)p;
+
+	ret = kmalloc(new_size, flags);
+	if (ret) {
+		memcpy(ret, p, min(new_size, ksize(p)));
+		kfree(p);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(krealloc);
+
+/********************************************************************
+ *			Basic setup of slabs
+ *******************************************************************/
+
+void __init kmem_cache_init(void)
+{
+	int i;
+
+#ifdef CONFIG_NUMA
+	/*
+	 * Must first have the slab cache available for the allocations of the
+	 * struct kmalloc_cache_node's. There is special bootstrap code in
+	 * kmem_cache_open for slab_state == DOWN.
+	 */
+	create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
+		sizeof(struct kmem_cache_node), GFP_KERNEL);
+#endif
+
+	/* Able to allocate the per node structures */
+	slab_state = PARTIAL;
+
+	/* Caches that are not of the two-to-the-power-of size */
+	create_kmalloc_cache(&kmalloc_caches[1],
+				"kmalloc-96", 96, GFP_KERNEL);
+	create_kmalloc_cache(&kmalloc_caches[2],
+				"kmalloc-192", 192, GFP_KERNEL);
+
+	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
+		create_kmalloc_cache(&kmalloc_caches[i],
+			"kmalloc", 1 << i, GFP_KERNEL);
+
+	slab_state = UP;
+
+	/* Provide the correct kmalloc names now that the caches are up */
+	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
+		kmalloc_caches[i]. name =
+			kasprintf(GFP_KERNEL, "kmalloc-%d", 1 << i);
+
+#ifdef CONFIG_SMP
+	register_cpu_notifier(&slab_notifier);
+#endif
+
+	if (nr_cpu_ids)	/* Remove when nr_cpu_ids is fixed upstream ! */
+		kmem_size = offsetof(struct kmem_cache, cpu_slab)
+			 + nr_cpu_ids * sizeof(struct page *);
+
+	printk(KERN_INFO "SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d,"
+		" Processors=%d, Nodes=%d\n",
+		KMALLOC_SHIFT_HIGH, L1_CACHE_BYTES,
+		slub_min_order, slub_max_order, slub_min_objects,
+		nr_cpu_ids, nr_node_ids);
+}
+
+/*
+ * Find a mergeable slab cache
+ */
+static int slab_unmergeable(struct kmem_cache *s)
+{
+	if (slub_nomerge || (s->flags & SLUB_NEVER_MERGE))
+		return 1;
+
+	if (s->ctor || s->dtor)
+		return 1;
+
+	return 0;
+}
+
+static struct kmem_cache *find_mergeable(size_t size,
+		size_t align, unsigned long flags,
+		void (*ctor)(void *, struct kmem_cache *, unsigned long),
+		void (*dtor)(void *, struct kmem_cache *, unsigned long))
+{
+	struct list_head *h;
+
+	if (slub_nomerge || (flags & SLUB_NEVER_MERGE))
+		return NULL;
+
+	if (ctor || dtor)
+		return NULL;
+
+	size = ALIGN(size, sizeof(void *));
+	align = calculate_alignment(flags, align, size);
+	size = ALIGN(size, align);
+
+	list_for_each(h, &slab_caches) {
+		struct kmem_cache *s =
+			container_of(h, struct kmem_cache, list);
+
+		if (slab_unmergeable(s))
+			continue;
+
+		if (size > s->size)
+			continue;
+
+		if (((flags | slub_debug) & SLUB_MERGE_SAME) !=
+			(s->flags & SLUB_MERGE_SAME))
+				continue;
+		/*
+		 * Check if alignment is compatible.
+		 * Courtesy of Adrian Drzewiecki
+		 */
+		if ((s->size & ~(align -1)) != s->size)
+			continue;
+
+		if (s->size - size >= sizeof(void *))
+			continue;
+
+		return s;
+	}
+	return NULL;
+}
+
+struct kmem_cache *kmem_cache_create(const char *name, size_t size,
+		size_t align, unsigned long flags,
+		void (*ctor)(void *, struct kmem_cache *, unsigned long),
+		void (*dtor)(void *, struct kmem_cache *, unsigned long))
+{
+	struct kmem_cache *s;
+
+	down_write(&slub_lock);
+	s = find_mergeable(size, align, flags, dtor, ctor);
+	if (s) {
+		s->refcount++;
+		/*
+		 * Adjust the object sizes so that we clear
+		 * the complete object on kzalloc.
+		 */
+		s->objsize = max(s->objsize, (int)size);
+		s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
+		if (sysfs_slab_alias(s, name))
+			goto err;
+	} else {
+		s = kmalloc(kmem_size, GFP_KERNEL);
+		if (s && kmem_cache_open(s, GFP_KERNEL, name,
+				size, align, flags, ctor, dtor)) {
+			if (sysfs_slab_add(s)) {
+				kfree(s);
+				goto err;
+			}
+			list_add(&s->list, &slab_caches);
+		} else
+			kfree(s);
+	}
+	up_write(&slub_lock);
+	return s;
+
+err:
+	up_write(&slub_lock);
+	if (flags & SLAB_PANIC)
+		panic("Cannot create slabcache %s\n", name);
+	else
+		s = NULL;
+	return s;
+}
+EXPORT_SYMBOL(kmem_cache_create);
+
+void *kmem_cache_zalloc(struct kmem_cache *s, gfp_t flags)
+{
+	void *x;
+
+	x = kmem_cache_alloc(s, flags);
+	if (x)
+		memset(x, 0, s->objsize);
+	return x;
+}
+EXPORT_SYMBOL(kmem_cache_zalloc);
+
+#ifdef CONFIG_SMP
+static void for_all_slabs(void (*func)(struct kmem_cache *, int), int cpu)
+{
+	struct list_head *h;
+
+	down_read(&slub_lock);
+	list_for_each(h, &slab_caches) {
+		struct kmem_cache *s =
+			container_of(h, struct kmem_cache, list);
+
+		func(s, cpu);
+	}
+	up_read(&slub_lock);
+}
+
+/*
+ * Use the cpu notifier to insure that the slab are flushed
+ * when necessary.
+ */
+static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb,
+		unsigned long action, void *hcpu)
+{
+	long cpu = (long)hcpu;
+
+	switch (action) {
+	case CPU_UP_CANCELED:
+	case CPU_DEAD:
+		for_all_slabs(__flush_cpu_slab, cpu);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata slab_notifier =
+	{ &slab_cpuup_callback, NULL, 0 };
+
+#endif
+
+/***************************************************************
+ *	Compatiblility definitions
+ **************************************************************/
+
+int kmem_cache_shrink(struct kmem_cache *s)
+{
+	flush_all(s);
+	return 0;
+}
+EXPORT_SYMBOL(kmem_cache_shrink);
+
+#ifdef CONFIG_NUMA
+
+/*****************************************************************
+ * Generic reaper used to support the page allocator
+ * (the cpu slabs are reaped by a per slab workqueue).
+ *
+ * Maybe move this to the page allocator?
+ ****************************************************************/
+
+static DEFINE_PER_CPU(unsigned long, reap_node);
+
+static void init_reap_node(int cpu)
+{
+	int node;
+
+	node = next_node(cpu_to_node(cpu), node_online_map);
+	if (node == MAX_NUMNODES)
+		node = first_node(node_online_map);
+
+	__get_cpu_var(reap_node) = node;
+}
+
+static void next_reap_node(void)
+{
+	int node = __get_cpu_var(reap_node);
+
+	/*
+	 * Also drain per cpu pages on remote zones
+	 */
+	if (node != numa_node_id())
+		drain_node_pages(node);
+
+	node = next_node(node, node_online_map);
+	if (unlikely(node >= MAX_NUMNODES))
+		node = first_node(node_online_map);
+	__get_cpu_var(reap_node) = node;
+}
+#else
+#define init_reap_node(cpu) do { } while (0)
+#define next_reap_node(void) do { } while (0)
+#endif
+
+#define REAPTIMEOUT_CPUC	(2*HZ)
+
+#ifdef CONFIG_SMP
+static DEFINE_PER_CPU(struct delayed_work, reap_work);
+
+static void cache_reap(struct work_struct *unused)
+{
+	next_reap_node();
+	refresh_cpu_vm_stats(smp_processor_id());
+	schedule_delayed_work(&__get_cpu_var(reap_work),
+				      REAPTIMEOUT_CPUC);
+}
+
+static void __devinit start_cpu_timer(int cpu)
+{
+	struct delayed_work *reap_work = &per_cpu(reap_work, cpu);
+
+	/*
+	 * When this gets called from do_initcalls via cpucache_init(),
+	 * init_workqueues() has already run, so keventd will be setup
+	 * at that time.
+	 */
+	if (keventd_up() && reap_work->work.func == NULL) {
+		init_reap_node(cpu);
+		INIT_DELAYED_WORK(reap_work, cache_reap);
+		schedule_delayed_work_on(cpu, reap_work, HZ + 3 * cpu);
+	}
+}
+
+static int __init cpucache_init(void)
+{
+	int cpu;
+
+	/*
+	 * Register the timers that drain pcp pages and update vm statistics
+	 */
+	for_each_online_cpu(cpu)
+		start_cpu_timer(cpu);
+	return 0;
+}
+__initcall(cpucache_init);
+#endif
+
+#ifdef SLUB_RESILIENCY_TEST
+static unsigned long validate_slab_cache(struct kmem_cache *s);
+
+static void resiliency_test(void)
+{
+	u8 *p;
+
+	printk(KERN_ERR "SLUB resiliency testing\n");
+	printk(KERN_ERR "-----------------------\n");
+	printk(KERN_ERR "A. Corruption after allocation\n");
+
+	p = kzalloc(16, GFP_KERNEL);
+	p[16] = 0x12;
+	printk(KERN_ERR "\n1. kmalloc-16: Clobber Redzone/next pointer"
+			" 0x12->0x%p\n\n", p + 16);
+
+	validate_slab_cache(kmalloc_caches + 4);
+
+	/* Hmmm... The next two are dangerous */
+	p = kzalloc(32, GFP_KERNEL);
+	p[32 + sizeof(void *)] = 0x34;
+	printk(KERN_ERR "\n2. kmalloc-32: Clobber next pointer/next slab"
+		 	" 0x34 -> -0x%p\n", p);
+	printk(KERN_ERR "If allocated object is overwritten then not detectable\n\n");
+
+	validate_slab_cache(kmalloc_caches + 5);
+	p = kzalloc(64, GFP_KERNEL);
+	p += 64 + (get_cycles() & 0xff) * sizeof(void *);
+	*p = 0x56;
+	printk(KERN_ERR "\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
+									p);
+	printk(KERN_ERR "If allocated object is overwritten then not detectable\n\n");
+	validate_slab_cache(kmalloc_caches + 6);
+
+	printk(KERN_ERR "\nB. Corruption after free\n");
+	p = kzalloc(128, GFP_KERNEL);
+	kfree(p);
+	*p = 0x78;
+	printk(KERN_ERR "1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
+	validate_slab_cache(kmalloc_caches + 7);
+
+	p = kzalloc(256, GFP_KERNEL);
+	kfree(p);
+	p[50] = 0x9a;
+	printk(KERN_ERR "\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
+	validate_slab_cache(kmalloc_caches + 8);
+
+	p = kzalloc(512, GFP_KERNEL);
+	kfree(p);
+	p[512] = 0xab;
+	printk(KERN_ERR "\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
+	validate_slab_cache(kmalloc_caches + 9);
+}
+#else
+static void resiliency_test(void) {};
+#endif
+
+/*
+ * These are not as efficient as kmalloc for the non debug case.
+ * We do not have the page struct available so we have to touch one
+ * cacheline in struct kmem_cache to check slab flags.
+ */
+void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, void *caller)
+{
+	struct kmem_cache *s = get_slab(size, gfpflags);
+	void *object;
+
+	if (!s)
+		return NULL;
+
+	object = kmem_cache_alloc(s, gfpflags);
+
+	if (object && (s->flags & SLAB_STORE_USER))
+		set_track(s, object, TRACK_ALLOC, caller);
+
+	return object;
+}
+
+void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
+					int node, void *caller)
+{
+	struct kmem_cache *s = get_slab(size, gfpflags);
+	void *object;
+
+	if (!s)
+		return NULL;
+
+	object = kmem_cache_alloc_node(s, gfpflags, node);
+
+	if (object && (s->flags & SLAB_STORE_USER))
+		set_track(s, object, TRACK_ALLOC, caller);
+
+	return object;
+}
+
+#ifdef CONFIG_SYSFS
+
+static unsigned long count_partial(struct kmem_cache_node *n)
+{
+	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 += page->inuse;
+	spin_unlock_irqrestore(&n->list_lock, flags);
+	return x;
+}
+
+enum slab_stat_type {
+	SL_FULL,
+	SL_PARTIAL,
+	SL_CPU,
+	SL_OBJECTS
+};
+
+#define SO_FULL		(1 << SL_FULL)
+#define SO_PARTIAL	(1 << SL_PARTIAL)
+#define SO_CPU		(1 << SL_CPU)
+#define SO_OBJECTS	(1 << SL_OBJECTS)
+
+static unsigned long slab_objects(struct kmem_cache *s,
+			char *buf, unsigned long flags)
+{
+	unsigned long total = 0;
+	int cpu;
+	int node;
+	int x;
+	unsigned long *nodes;
+	unsigned long *per_cpu;
+
+	nodes = kzalloc(2 * sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
+	per_cpu = nodes + nr_node_ids;
+
+	for_each_possible_cpu(cpu) {
+		struct page *page = s->cpu_slab[cpu];
+		int node;
+
+		if (page) {
+			node = page_to_nid(page);
+			if (flags & SO_CPU) {
+				int x = 0;
+
+				if (flags & SO_OBJECTS)
+					x = page->inuse;
+				else
+					x = 1;
+				total += x;
+				nodes[node] += x;
+			}
+			per_cpu[node]++;
+		}
+	}
+
+	for_each_online_node(node) {
+		struct kmem_cache_node *n = get_node(s, node);
+
+		if (flags & SO_PARTIAL) {
+			if (flags & SO_OBJECTS)
+				x = count_partial(n);
+			else
+				x = n->nr_partial;
+			total += x;
+			nodes[node] += x;
+		}
+
+		if (flags & SO_FULL) {
+			int full_slabs = atomic_read(&n->nr_slabs)
+					- per_cpu[node]
+					- n->nr_partial;
+
+			if (flags & SO_OBJECTS)
+				x = full_slabs * s->objects;
+			else
+				x = full_slabs;
+			total += x;
+			nodes[node] += x;
+		}
+	}
+
+	x = sprintf(buf, "%lu", total);
+#ifdef CONFIG_NUMA
+	for_each_online_node(node)
+		if (nodes[node])
+			x += sprintf(buf + x, " N%d=%lu",
+					node, nodes[node]);
+#endif
+	kfree(nodes);
+	return x + sprintf(buf + x, "\n");
+}
+
+static int any_slab_objects(struct kmem_cache *s)
+{
+	int node;
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		if (s->cpu_slab[cpu])
+			return 1;
+
+	for_each_node(node) {
+		struct kmem_cache_node *n = get_node(s, node);
+
+		if (n->nr_partial || atomic_read(&n->nr_slabs))
+			return 1;
+	}
+	return 0;
+}
+
+#define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
+#define to_slab(n) container_of(n, struct kmem_cache, kobj);
+
+struct slab_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct kmem_cache *s, char *buf);
+	ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
+};
+
+#define SLAB_ATTR_RO(_name) \
+	static struct slab_attribute _name##_attr = __ATTR_RO(_name)
+
+#define SLAB_ATTR(_name) \
+	static struct slab_attribute _name##_attr =  \
+	__ATTR(_name, 0644, _name##_show, _name##_store)
+
+
+static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->size);
+}
+SLAB_ATTR_RO(slab_size);
+
+static ssize_t align_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->align);
+}
+SLAB_ATTR_RO(align);
+
+static ssize_t object_size_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->objsize);
+}
+SLAB_ATTR_RO(object_size);
+
+static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->objects);
+}
+SLAB_ATTR_RO(objs_per_slab);
+
+static ssize_t order_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->order);
+}
+SLAB_ATTR_RO(order);
+
+static ssize_t ctor_show(struct kmem_cache *s, char *buf)
+{
+	if (s->ctor) {
+		int n = sprint_symbol(buf, (unsigned long)s->ctor);
+
+		return n + sprintf(buf + n, "\n");
+	}
+	return 0;
+}
+SLAB_ATTR_RO(ctor);
+
+static ssize_t dtor_show(struct kmem_cache *s, char *buf)
+{
+	if (s->dtor) {
+		int n = sprint_symbol(buf, (unsigned long)s->dtor);
+
+		return n + sprintf(buf + n, "\n");
+	}
+	return 0;
+}
+SLAB_ATTR_RO(dtor);
+
+static ssize_t aliases_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->refcount - 1);
+}
+SLAB_ATTR_RO(aliases);
+
+static ssize_t slabs_show(struct kmem_cache *s, char *buf)
+{
+	return slab_objects(s, buf, SO_FULL|SO_PARTIAL|SO_CPU);
+}
+SLAB_ATTR_RO(slabs);
+
+static ssize_t partial_show(struct kmem_cache *s, char *buf)
+{
+	return slab_objects(s, buf, SO_PARTIAL);
+}
+SLAB_ATTR_RO(partial);
+
+static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
+{
+	return slab_objects(s, buf, SO_CPU);
+}
+SLAB_ATTR_RO(cpu_slabs);
+
+static ssize_t objects_show(struct kmem_cache *s, char *buf)
+{
+	return slab_objects(s, buf, SO_FULL|SO_PARTIAL|SO_CPU|SO_OBJECTS);
+}
+SLAB_ATTR_RO(objects);
+
+static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DEBUG_FREE));
+}
+
+static ssize_t sanity_checks_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	s->flags &= ~SLAB_DEBUG_FREE;
+	if (buf[0] == '1')
+		s->flags |= SLAB_DEBUG_FREE;
+	return length;
+}
+SLAB_ATTR(sanity_checks);
+
+static ssize_t trace_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
+}
+
+static ssize_t trace_store(struct kmem_cache *s, const char *buf,
+							size_t length)
+{
+	s->flags &= ~SLAB_TRACE;
+	if (buf[0] == '1')
+		s->flags |= SLAB_TRACE;
+	return length;
+}
+SLAB_ATTR(trace);
+
+static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
+}
+
+static ssize_t reclaim_account_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	s->flags &= ~SLAB_RECLAIM_ACCOUNT;
+	if (buf[0] == '1')
+		s->flags |= SLAB_RECLAIM_ACCOUNT;
+	return length;
+}
+SLAB_ATTR(reclaim_account);
+
+static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags &
+		(SLAB_HWCACHE_ALIGN|SLAB_MUST_HWCACHE_ALIGN)));
+}
+SLAB_ATTR_RO(hwcache_align);
+
+#ifdef CONFIG_ZONE_DMA
+static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
+}
+SLAB_ATTR_RO(cache_dma);
+#endif
+
+static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
+}
+SLAB_ATTR_RO(destroy_by_rcu);
+
+static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
+}
+
+static ssize_t red_zone_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	if (any_slab_objects(s))
+		return -EBUSY;
+
+	s->flags &= ~SLAB_RED_ZONE;
+	if (buf[0] == '1')
+		s->flags |= SLAB_RED_ZONE;
+	calculate_sizes(s);
+	return length;
+}
+SLAB_ATTR(red_zone);
+
+static ssize_t poison_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
+}
+
+static ssize_t poison_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	if (any_slab_objects(s))
+		return -EBUSY;
+
+	s->flags &= ~SLAB_POISON;
+	if (buf[0] == '1')
+		s->flags |= SLAB_POISON;
+	calculate_sizes(s);
+	return length;
+}
+SLAB_ATTR(poison);
+
+static ssize_t store_user_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
+}
+
+static ssize_t store_user_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	if (any_slab_objects(s))
+		return -EBUSY;
+
+	s->flags &= ~SLAB_STORE_USER;
+	if (buf[0] == '1')
+		s->flags |= SLAB_STORE_USER;
+	calculate_sizes(s);
+	return length;
+}
+SLAB_ATTR(store_user);
+
+#ifdef CONFIG_NUMA
+static ssize_t defrag_ratio_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", s->defrag_ratio / 10);
+}
+
+static ssize_t defrag_ratio_store(struct kmem_cache *s,
+				const char *buf, size_t length)
+{
+	int n = simple_strtoul(buf, NULL, 10);
+
+	if (n < 100)
+		s->defrag_ratio = n * 10;
+	return length;
+}
+SLAB_ATTR(defrag_ratio);
+#endif
+
+static struct attribute * slab_attrs[] = {
+	&slab_size_attr.attr,
+	&object_size_attr.attr,
+	&objs_per_slab_attr.attr,
+	&order_attr.attr,
+	&objects_attr.attr,
+	&slabs_attr.attr,
+	&partial_attr.attr,
+	&cpu_slabs_attr.attr,
+	&ctor_attr.attr,
+	&dtor_attr.attr,
+	&aliases_attr.attr,
+	&align_attr.attr,
+	&sanity_checks_attr.attr,
+	&trace_attr.attr,
+	&hwcache_align_attr.attr,
+	&reclaim_account_attr.attr,
+	&destroy_by_rcu_attr.attr,
+	&red_zone_attr.attr,
+	&poison_attr.attr,
+	&store_user_attr.attr,
+#ifdef CONFIG_ZONE_DMA
+	&cache_dma_attr.attr,
+#endif
+#ifdef CONFIG_NUMA
+	&defrag_ratio_attr.attr,
+#endif
+	NULL
+};
+
+static struct attribute_group slab_attr_group = {
+	.attrs = slab_attrs,
+};
+
+static ssize_t slab_attr_show(struct kobject *kobj,
+				struct attribute *attr,
+				char *buf)
+{
+	struct slab_attribute *attribute;
+	struct kmem_cache *s;
+	int err;
+
+	attribute = to_slab_attr(attr);
+	s = to_slab(kobj);
+
+	if (!attribute->show)
+		return -EIO;
+
+	err = attribute->show(s, buf);
+
+	return err;
+}
+
+static ssize_t slab_attr_store(struct kobject *kobj,
+				struct attribute *attr,
+				const char *buf, size_t len)
+{
+	struct slab_attribute *attribute;
+	struct kmem_cache *s;
+	int err;
+
+	attribute = to_slab_attr(attr);
+	s = to_slab(kobj);
+
+	if (!attribute->store)
+		return -EIO;
+
+	err = attribute->store(s, buf, len);
+
+	return err;
+}
+
+static struct sysfs_ops slab_sysfs_ops = {
+	.show = slab_attr_show,
+	.store = slab_attr_store,
+};
+
+static struct kobj_type slab_ktype = {
+	.sysfs_ops = &slab_sysfs_ops,
+};
+
+static int uevent_filter(struct kset *kset, struct kobject *kobj)
+{
+	struct kobj_type *ktype = get_ktype(kobj);
+
+	if (ktype == &slab_ktype)
+		return 1;
+	return 0;
+}
+
+static struct kset_uevent_ops slab_uevent_ops = {
+	.filter = uevent_filter,
+};
+
+decl_subsys(slab, &slab_ktype, &slab_uevent_ops);
+
+#define ID_STR_LENGTH 64
+
+/* Create a unique string id for a slab cache:
+ * format
+ * :[flags-]size:[memory address of kmemcache]
+ */
+static char *create_unique_id(struct kmem_cache *s)
+{
+	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
+	char *p = name;
+
+	BUG_ON(!name);
+
+	*p++ = ':';
+	/*
+	 * First flags affecting slabcache operations. We will only
+	 * get here for aliasable slabs so we do not need to support
+	 * too many flags. The flags here must cover all flags that
+	 * are matched during merging to guarantee that the id is
+	 * unique.
+	 */
+	if (s->flags & SLAB_CACHE_DMA)
+		*p++ = 'd';
+	if (s->flags & SLAB_RECLAIM_ACCOUNT)
+		*p++ = 'a';
+	if (s->flags & SLAB_DEBUG_FREE)
+		*p++ = 'F';
+	if (p != name + 1)
+		*p++ = '-';
+	p += sprintf(p, "%07d", s->size);
+	BUG_ON(p > name + ID_STR_LENGTH - 1);
+	return name;
+}
+
+static int sysfs_slab_add(struct kmem_cache *s)
+{
+	int err;
+	const char *name;
+	int unmergeable;
+
+	if (slab_state < SYSFS)
+		/* Defer until later */
+		return 0;
+
+	unmergeable = slab_unmergeable(s);
+	if (unmergeable) {
+		/*
+		 * Slabcache can never be merged so we can use the name proper.
+		 * This is typically the case for debug situations. In that
+		 * case we can catch duplicate names easily.
+		 */
+		sysfs_remove_link(&slab_subsys.kset.kobj, s->name);
+		name = s->name;
+	} else {
+		/*
+		 * Create a unique name for the slab as a target
+		 * for the symlinks.
+		 */
+		name = create_unique_id(s);
+	}
+
+	kobj_set_kset_s(s, slab_subsys);
+	kobject_set_name(&s->kobj, name);
+	kobject_init(&s->kobj);
+	err = kobject_add(&s->kobj);
+	if (err)
+		return err;
+
+	err = sysfs_create_group(&s->kobj, &slab_attr_group);
+	if (err)
+		return err;
+	kobject_uevent(&s->kobj, KOBJ_ADD);
+	if (!unmergeable) {
+		/* Setup first alias */
+		sysfs_slab_alias(s, s->name);
+		kfree(name);
+	}
+	return 0;
+}
+
+static void sysfs_slab_remove(struct kmem_cache *s)
+{
+	kobject_uevent(&s->kobj, KOBJ_REMOVE);
+	kobject_del(&s->kobj);
+}
+
+/*
+ * Need to buffer aliases during bootup until sysfs becomes
+ * available lest we loose that information.
+ */
+struct saved_alias {
+	struct kmem_cache *s;
+	const char *name;
+	struct saved_alias *next;
+};
+
+struct saved_alias *alias_list;
+
+static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
+{
+	struct saved_alias *al;
+
+	if (slab_state == SYSFS) {
+		/*
+		 * If we have a leftover link then remove it.
+		 */
+		sysfs_remove_link(&slab_subsys.kset.kobj, name);
+		return sysfs_create_link(&slab_subsys.kset.kobj,
+						&s->kobj, name);
+	}
+
+	al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
+	if (!al)
+		return -ENOMEM;
+
+	al->s = s;
+	al->name = name;
+	al->next = alias_list;
+	alias_list = al;
+	return 0;
+}
+
+static int __init slab_sysfs_init(void)
+{
+	int err;
+
+	err = subsystem_register(&slab_subsys);
+	if (err) {
+		printk(KERN_ERR "Cannot register slab subsystem.\n");
+		return -ENOSYS;
+	}
+
+	finish_bootstrap();
+
+	while (alias_list) {
+		struct saved_alias *al = alias_list;
+
+		alias_list = alias_list->next;
+		err = sysfs_slab_alias(al->s, al->name);
+		BUG_ON(err);
+		kfree(al);
+	}
+
+	resiliency_test();
+	return 0;
+}
+
+__initcall(slab_sysfs_init);
+#else
+__initcall(finish_bootstrap);
+#endif