Common [0/4] Sl[auo]b: Common code rework V6 (limited)

Common [0/4] Sl[auo]b: Common code rework V6 (limited)

[Christoph Lameter]

V5->V6:
- Patches against Pekka's for-next tree.
- Go slow and cut down to just patches that are safe
  (there will likely be some churn already due to the
  mutex unification between slabs)
- More to come next week when I have more time (
  took me almost the whole week to catch up after
  being gone for awhile).

V4->V5
- Rediff against current upstream + Pekka's cleanup branch.

V3->V4:
- Do not use the COMMON macro anymore.
- Fixup various issues
- No general sysfs support yet due to lockdep issues with
  keys in kmalloc'ed memory.

V2->V3:
- Incorporate more feedback from Joonsoo Kim and Glauber Costa
- And a couple more patches to deal with slab duping and move
  more code to slab_common.c

V1->V2:
- Incorporate glommers feedback.
- Add 2 more patches dealing with common code in kmem_cache_destroy

This is a series of patches that extracts common functionality from
slab allocators into a common code base. The intend is to standardize
as much as possible of the allocator behavior while keeping the
distinctive features of each allocator which are mostly due to their
storage format and serialization approaches.

This patchset makes a beginning by extracting common functionality in
kmem_cache_create() and kmem_cache_destroy(). However, there are
numerous other areas where such work could be beneficial:

1. Extract the sysfs support from SLUB and make it common. That way
   all allocators have a common sysfs API and are handleable in the same
   way regardless of the allocator chose.

2. Extract the error reporting and checking from SLUB and make
   it available for all allocators. This means that all allocators
   will gain the resiliency and error handling capabilties.

3. Extract the memory hotplug and cpu hotplug handling. It seems that
   SLAB may be more sophisticated here. Having common code here will
   make it easier to maintain the special code.

4. Extract the aliasing capability of SLUB. This will enable fast
   slab creation without creating too many additional slab caches.
   The arrays of caches of varying sizes in numerous subsystems
   do not cause the creation of numerous slab caches. Storage
   density is increased and the cache footprint is reduced.

Ultimately it is to be hoped that the special code for each allocator
shrinks to a mininum. This will also make it easier to make modification
to allocators.

In the far future one could envision that the current allocators will
just become storage algorithms that can be chosen based on the need of
the subsystem. F.e.

Cpu cache dependend performance		= Bonwick allocator (SLAB)
Minimal cycle count and cache footprint	= SLUB
Maximum storage density			= K&R allocator (SLOB)


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Common [1/4] Extract common code for kmem_cache_create()

[Christoph Lameter]

[-- Attachment #1: common_kmem_cache_checks --]
[-- Type: text/plain, Size: 9758 bytes --]

Kmem_cache_create() does a variety of sanity checks but those
vary depending on the allocator. Use the strictest tests and put them into
a slab_common file. Make the tests conditional on CONFIG_DEBUG_VM.

This patch has the effect of adding sanity checks for SLUB and SLOB
under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/slab.h |    4 ++
 mm/Makefile          |    3 +-
 mm/slab.c            |   24 ++++++-----------
 mm/slab_common.c     |   69 +++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/slob.c            |    8 ++---
 mm/slub.c            |   11 --------
 6 files changed, 88 insertions(+), 31 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-07-06 07:29:01.643292029 -0500
+++ linux-2.6/mm/slab.c	2012-07-06 07:30:09.119290631 -0500
@@ -1558,7 +1558,7 @@ void __init kmem_cache_init(void)
 	 * bug.
 	 */
 
-	sizes[INDEX_AC].cs_cachep = kmem_cache_create(names[INDEX_AC].name,
+	sizes[INDEX_AC].cs_cachep = __kmem_cache_create(names[INDEX_AC].name,
 					sizes[INDEX_AC].cs_size,
 					ARCH_KMALLOC_MINALIGN,
 					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
@@ -1566,7 +1566,7 @@ void __init kmem_cache_init(void)
 
 	if (INDEX_AC != INDEX_L3) {
 		sizes[INDEX_L3].cs_cachep =
-			kmem_cache_create(names[INDEX_L3].name,
+			__kmem_cache_create(names[INDEX_L3].name,
 				sizes[INDEX_L3].cs_size,
 				ARCH_KMALLOC_MINALIGN,
 				ARCH_KMALLOC_FLAGS|SLAB_PANIC,
@@ -1584,14 +1584,14 @@ void __init kmem_cache_init(void)
 		 * allow tighter packing of the smaller caches.
 		 */
 		if (!sizes->cs_cachep) {
-			sizes->cs_cachep = kmem_cache_create(names->name,
+			sizes->cs_cachep = __kmem_cache_create(names->name,
 					sizes->cs_size,
 					ARCH_KMALLOC_MINALIGN,
 					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
 					NULL);
 		}
 #ifdef CONFIG_ZONE_DMA
-		sizes->cs_dmacachep = kmem_cache_create(
+		sizes->cs_dmacachep = __kmem_cache_create(
 					names->name_dma,
 					sizes->cs_size,
 					ARCH_KMALLOC_MINALIGN,
@@ -2220,7 +2220,7 @@ static int __init_refok setup_cpu_cache(
 }
 
 /**
- * kmem_cache_create - Create a cache.
+ * __kmem_cache_create - Create a cache.
  * @name: A string which is used in /proc/slabinfo to identify this cache.
  * @size: The size of objects to be created in this cache.
  * @align: The required alignment for the objects.
@@ -2247,7 +2247,7 @@ static int __init_refok setup_cpu_cache(
  * as davem.
  */
 struct kmem_cache *
-kmem_cache_create (const char *name, size_t size, size_t align,
+__kmem_cache_create (const char *name, size_t size, size_t align,
 	unsigned long flags, void (*ctor)(void *))
 {
 	size_t left_over, slab_size, ralign;
@@ -2388,7 +2388,7 @@ kmem_cache_create (const char *name, siz
 	/* Get cache's description obj. */
 	cachep = kmem_cache_zalloc(&cache_cache, gfp);
 	if (!cachep)
-		goto oops;
+		return NULL;
 
 	cachep->nodelists = (struct kmem_list3 **)&cachep->array[nr_cpu_ids];
 	cachep->object_size = size;
@@ -2445,8 +2445,7 @@ kmem_cache_create (const char *name, siz
 		printk(KERN_ERR
 		       "kmem_cache_create: couldn't create cache %s.\n", name);
 		kmem_cache_free(&cache_cache, cachep);
-		cachep = NULL;
-		goto oops;
+		return NULL;
 	}
 	slab_size = ALIGN(cachep->num * sizeof(kmem_bufctl_t)
 			  + sizeof(struct slab), align);
@@ -2504,8 +2503,7 @@ kmem_cache_create (const char *name, siz
 
 	if (setup_cpu_cache(cachep, gfp)) {
 		__kmem_cache_destroy(cachep);
-		cachep = NULL;
-		goto oops;
+		return NULL;
 	}
 
 	if (flags & SLAB_DEBUG_OBJECTS) {
@@ -2521,16 +2519,12 @@ kmem_cache_create (const char *name, siz
 	/* cache setup completed, link it into the list */
 	list_add(&cachep->list, &cache_chain);
 oops:
-	if (!cachep && (flags & SLAB_PANIC))
-		panic("kmem_cache_create(): failed to create slab `%s'\n",
-		      name);
 	if (slab_is_available()) {
 		mutex_unlock(&cache_chain_mutex);
 		put_online_cpus();
 	}
 	return cachep;
 }
-EXPORT_SYMBOL(kmem_cache_create);
 
 #if DEBUG
 static void check_irq_off(void)
Index: linux-2.6/mm/slab_common.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/mm/slab_common.c	2012-07-06 07:30:09.119290631 -0500
@@ -0,0 +1,69 @@
+/*
+ * Slab allocator functions that are independent of the allocator strategy
+ *
+ * (C) 2012 Christoph Lameter <cl@linux.com>
+ */
+#include <linux/slab.h>
+
+#include <linux/mm.h>
+#include <linux/poison.h>
+#include <linux/interrupt.h>
+#include <linux/memory.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+
+/*
+ * kmem_cache_create - Create a cache.
+ * @name: A string which is used in /proc/slabinfo to identify this cache.
+ * @size: The size of objects to be created in this cache.
+ * @align: The required alignment for the objects.
+ * @flags: SLAB flags
+ * @ctor: A constructor for the objects.
+ *
+ * Returns a ptr to the cache on success, NULL on failure.
+ * Cannot be called within a interrupt, but can be interrupted.
+ * The @ctor is run when new pages are allocated by the cache.
+ *
+ * The flags are
+ *
+ * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
+ * to catch references to uninitialised memory.
+ *
+ * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
+ * for buffer overruns.
+ *
+ * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
+ * cacheline.  This can be beneficial if you're counting cycles as closely
+ * as davem.
+ */
+
+struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
+		unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *s = NULL;
+
+#ifdef CONFIG_DEBUG_VM
+	if (!name || in_interrupt() || size < sizeof(void *) ||
+		size > KMALLOC_MAX_SIZE) {
+		printk(KERN_ERR "kmem_cache_create(%s) integrity check"
+			" failed\n", name);
+		goto out;
+	}
+#endif
+
+	s = __kmem_cache_create(name, size, align, flags, ctor);
+
+#ifdef CONFIG_DEBUG_VM
+out:
+#endif
+	if (!s && (flags & SLAB_PANIC))
+		panic("kmem_cache_create: Failed to create slab '%s'\n", name);
+
+	return s;
+}
+EXPORT_SYMBOL(kmem_cache_create);
+
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-07-06 07:30:05.939290696 -0500
+++ linux-2.6/mm/slub.c	2012-07-06 07:30:09.119290631 -0500
@@ -3919,15 +3919,12 @@ static struct kmem_cache *find_mergeable
 	return NULL;
 }
 
-struct kmem_cache *kmem_cache_create(const char *name, size_t size,
+struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 		size_t align, unsigned long flags, void (*ctor)(void *))
 {
 	struct kmem_cache *s;
 	char *n;
 
-	if (WARN_ON(!name))
-		return NULL;
-
 	down_write(&slub_lock);
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
@@ -3971,14 +3968,8 @@ struct kmem_cache *kmem_cache_create(con
 	kfree(n);
 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);
 
 #ifdef CONFIG_SMP
 /*
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-07-06 07:29:01.635292029 -0500
+++ linux-2.6/mm/slob.c	2012-07-06 07:30:09.119290631 -0500
@@ -506,7 +506,7 @@ size_t ksize(const void *block)
 }
 EXPORT_SYMBOL(ksize);
 
-struct kmem_cache *kmem_cache_create(const char *name, size_t size,
+struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *))
 {
 	struct kmem_cache *c;
@@ -529,13 +529,11 @@ struct kmem_cache *kmem_cache_create(con
 			c->align = ARCH_SLAB_MINALIGN;
 		if (c->align < align)
 			c->align = align;
-	} else if (flags & SLAB_PANIC)
-		panic("Cannot create slab cache %s\n", name);
 
-	kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
+		kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
+	}
 	return c;
 }
-EXPORT_SYMBOL(kmem_cache_create);
 
 void kmem_cache_destroy(struct kmem_cache *c)
 {
Index: linux-2.6/mm/Makefile
===================================================================
--- linux-2.6.orig/mm/Makefile	2012-07-06 07:29:01.663292030 -0500
+++ linux-2.6/mm/Makefile	2012-07-06 07:30:09.119290631 -0500
@@ -16,7 +16,8 @@ obj-y			:= filemap.o mempool.o oom_kill.
 			   readahead.o swap.o truncate.o vmscan.o shmem.o \
 			   prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
 			   page_isolation.o mm_init.o mmu_context.o percpu.o \
-			   compaction.o $(mmu-y)
+			   compaction.o slab_common.o $(mmu-y)
+
 obj-y += init-mm.o
 
 ifdef CONFIG_NO_BOOTMEM
Index: linux-2.6/include/linux/slab.h
===================================================================
--- linux-2.6.orig/include/linux/slab.h	2012-07-06 07:29:01.627292029 -0500
+++ linux-2.6/include/linux/slab.h	2012-07-06 07:30:09.119290631 -0500
@@ -130,6 +130,10 @@ int kmem_cache_shrink(struct kmem_cache
 void kmem_cache_free(struct kmem_cache *, void *);
 unsigned int kmem_cache_size(struct kmem_cache *);
 
+/* Slab internal function */
+struct kmem_cache *__kmem_cache_create(const char *, size_t, size_t,
+			unsigned long,
+			void (*)(void *));
 /*
  * Please use this macro to create slab caches. Simply specify the
  * name of the structure and maybe some flags that are listed above.

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Common [2/4] Common definition for boot state of the slab allocators

[Christoph Lameter]

[-- Attachment #1: slab_internal --]
[-- Type: text/plain, Size: 9295 bytes --]

All allocators have some sort of support for the bootstrap status.

Setup a common definition for the boot states and make all slab
allocators use that definition.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/slab.h |    4 ----
 mm/slab.c            |   45 ++++++++++++++-------------------------------
 mm/slab.h            |   30 ++++++++++++++++++++++++++++++
 mm/slab_common.c     |    9 +++++++++
 mm/slob.c            |   14 +++++---------
 mm/slub.c            |   21 +++++----------------
 6 files changed, 63 insertions(+), 60 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-07-06 08:43:04.495199970 -0500
+++ linux-2.6/mm/slab.c	2012-07-06 08:43:58.847198851 -0500
@@ -87,6 +87,7 @@
  */
 
 #include	<linux/slab.h>
+#include	"slab.h"
 #include	<linux/mm.h>
 #include	<linux/poison.h>
 #include	<linux/swap.h>
@@ -565,27 +566,6 @@ static struct kmem_cache cache_cache = {
 
 #define BAD_ALIEN_MAGIC 0x01020304ul
 
-/*
- * chicken and egg problem: delay the per-cpu array allocation
- * until the general caches are up.
- */
-static enum {
-	NONE,
-	PARTIAL_AC,
-	PARTIAL_L3,
-	EARLY,
-	LATE,
-	FULL
-} g_cpucache_up;
-
-/*
- * used by boot code to determine if it can use slab based allocator
- */
-int slab_is_available(void)
-{
-	return g_cpucache_up >= EARLY;
-}
-
 #ifdef CONFIG_LOCKDEP
 
 /*
@@ -651,7 +631,7 @@ static void init_node_lock_keys(int q)
 {
 	struct cache_sizes *s = malloc_sizes;
 
-	if (g_cpucache_up < LATE)
+	if (slab_state < UP)
 		return;
 
 	for (s = malloc_sizes; s->cs_size != ULONG_MAX; s++) {
@@ -1649,14 +1629,14 @@ void __init kmem_cache_init(void)
 		}
 	}
 
-	g_cpucache_up = EARLY;
+	slab_state = UP;
 }
 
 void __init kmem_cache_init_late(void)
 {
 	struct kmem_cache *cachep;
 
-	g_cpucache_up = LATE;
+	slab_state = UP;
 
 	/* Annotate slab for lockdep -- annotate the malloc caches */
 	init_lock_keys();
@@ -1668,6 +1648,9 @@ void __init kmem_cache_init_late(void)
 			BUG();
 	mutex_unlock(&cache_chain_mutex);
 
+	/* Done! */
+	slab_state = FULL;
+
 	/*
 	 * Register a cpu startup notifier callback that initializes
 	 * cpu_cache_get for all new cpus
@@ -1699,7 +1682,7 @@ static int __init cpucache_init(void)
 		start_cpu_timer(cpu);
 
 	/* Done! */
-	g_cpucache_up = FULL;
+	slab_state = FULL;
 	return 0;
 }
 __initcall(cpucache_init);
@@ -2167,10 +2150,10 @@ static size_t calculate_slab_order(struc
 
 static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
 {
-	if (g_cpucache_up >= LATE)
+	if (slab_state >= FULL)
 		return enable_cpucache(cachep, gfp);
 
-	if (g_cpucache_up == NONE) {
+	if (slab_state == DOWN) {
 		/*
 		 * Note: the first kmem_cache_create must create the cache
 		 * that's used by kmalloc(24), otherwise the creation of
@@ -2185,16 +2168,16 @@ static int __init_refok setup_cpu_cache(
 		 */
 		set_up_list3s(cachep, SIZE_AC);
 		if (INDEX_AC == INDEX_L3)
-			g_cpucache_up = PARTIAL_L3;
+			slab_state = PARTIAL_L3;
 		else
-			g_cpucache_up = PARTIAL_AC;
+			slab_state = PARTIAL_ARRAYCACHE;
 	} else {
 		cachep->array[smp_processor_id()] =
 			kmalloc(sizeof(struct arraycache_init), gfp);
 
-		if (g_cpucache_up == PARTIAL_AC) {
+		if (slab_state == PARTIAL_ARRAYCACHE) {
 			set_up_list3s(cachep, SIZE_L3);
-			g_cpucache_up = PARTIAL_L3;
+			slab_state = PARTIAL_L3;
 		} else {
 			int node;
 			for_each_online_node(node) {
Index: linux-2.6/mm/slab.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/mm/slab.h	2012-07-06 08:43:20.759199635 -0500
@@ -0,0 +1,30 @@
+#ifndef MM_SLAB_H
+#define MM_SLAB_H
+/*
+ * Internal slab definitions
+ */
+
+/*
+ * State of the slab allocator.
+ *
+ * This is used to describe the states of the allocator during bootup.
+ * Allocators use this to gradually bootstrap themselves. Most allocators
+ * have the problem that the structures used for managing slab caches are
+ * allocated from slab caches themselves.
+ */
+enum slab_state {
+	DOWN,			/* No slab functionality yet */
+	PARTIAL,		/* SLUB: kmem_cache_node available */
+	PARTIAL_ARRAYCACHE,	/* SLAB: kmalloc size for arraycache available */
+	PARTIAL_L3,		/* SLAB: kmalloc size for l3 struct available */
+	UP,			/* Slab caches usable but not all extras yet */
+	FULL			/* Everything is working */
+};
+
+extern enum slab_state slab_state;
+
+struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
+	size_t align, unsigned long flags, void (*ctor)(void *));
+
+#endif
+
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-07-06 08:43:04.499199970 -0500
+++ linux-2.6/mm/slob.c	2012-07-06 08:43:20.759199635 -0500
@@ -59,6 +59,8 @@
 
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include "slab.h"
+
 #include <linux/mm.h>
 #include <linux/swap.h> /* struct reclaim_state */
 #include <linux/cache.h>
@@ -531,6 +533,7 @@ struct kmem_cache *__kmem_cache_create(c
 			c->align = align;
 
 		kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
+		c->refcount = 1;
 	}
 	return c;
 }
@@ -616,19 +619,12 @@ int kmem_cache_shrink(struct kmem_cache
 }
 EXPORT_SYMBOL(kmem_cache_shrink);
 
-static unsigned int slob_ready __read_mostly;
-
-int slab_is_available(void)
-{
-	return slob_ready;
-}
-
 void __init kmem_cache_init(void)
 {
-	slob_ready = 1;
+	slab_state = UP;
 }
 
 void __init kmem_cache_init_late(void)
 {
-	/* Nothing to do */
+	slab_state = FULL;
 }
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-07-06 08:43:04.495199970 -0500
+++ linux-2.6/mm/slub.c	2012-07-06 08:43:20.759199635 -0500
@@ -16,6 +16,7 @@
 #include <linux/interrupt.h>
 #include <linux/bitops.h>
 #include <linux/slab.h>
+#include "slab.h"
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/kmemcheck.h>
@@ -182,13 +183,6 @@ static int kmem_size = sizeof(struct kme
 static struct notifier_block slab_notifier;
 #endif
 
-static enum {
-	DOWN,		/* No slab functionality available */
-	PARTIAL,	/* Kmem_cache_node works */
-	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);
@@ -237,11 +231,6 @@ static inline void stat(const struct kme
  * 			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)
 {
 	return s->node[node];
@@ -5273,7 +5262,7 @@ static int sysfs_slab_add(struct kmem_ca
 	const char *name;
 	int unmergeable;
 
-	if (slab_state < SYSFS)
+	if (slab_state < FULL)
 		/* Defer until later */
 		return 0;
 
@@ -5318,7 +5307,7 @@ static int sysfs_slab_add(struct kmem_ca
 
 static void sysfs_slab_remove(struct kmem_cache *s)
 {
-	if (slab_state < SYSFS)
+	if (slab_state < FULL)
 		/*
 		 * Sysfs has not been setup yet so no need to remove the
 		 * cache from sysfs.
@@ -5346,7 +5335,7 @@ static int sysfs_slab_alias(struct kmem_
 {
 	struct saved_alias *al;
 
-	if (slab_state == SYSFS) {
+	if (slab_state == FULL) {
 		/*
 		 * If we have a leftover link then remove it.
 		 */
@@ -5379,7 +5368,7 @@ static int __init slab_sysfs_init(void)
 		return -ENOSYS;
 	}
 
-	slab_state = SYSFS;
+	slab_state = FULL;
 
 	list_for_each_entry(s, &slab_caches, list) {
 		err = sysfs_slab_add(s);
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-07-06 08:43:04.495199970 -0500
+++ linux-2.6/mm/slab_common.c	2012-07-06 08:43:20.759199635 -0500
@@ -16,6 +16,10 @@
 #include <asm/tlbflush.h>
 #include <asm/page.h>
 
+#include "slab.h"
+
+enum slab_state slab_state;
+
 /*
  * kmem_cache_create - Create a cache.
  * @name: A string which is used in /proc/slabinfo to identify this cache.
@@ -67,3 +71,8 @@ out:
 }
 EXPORT_SYMBOL(kmem_cache_create);
 
+int slab_is_available(void)
+{
+	return slab_state >= UP;
+}
+
Index: linux-2.6/include/linux/slab.h
===================================================================
--- linux-2.6.orig/include/linux/slab.h	2012-07-06 08:43:04.499199970 -0500
+++ linux-2.6/include/linux/slab.h	2012-07-06 08:43:20.759199635 -0500
@@ -130,10 +130,6 @@ int kmem_cache_shrink(struct kmem_cache
 void kmem_cache_free(struct kmem_cache *, void *);
 unsigned int kmem_cache_size(struct kmem_cache *);
 
-/* Slab internal function */
-struct kmem_cache *__kmem_cache_create(const char *, size_t, size_t,
-			unsigned long,
-			void (*)(void *));
 /*
  * Please use this macro to create slab caches. Simply specify the
  * name of the structure and maybe some flags that are listed above.

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Common [3/4] Use a common mutex definition

[Christoph Lameter]

[-- Attachment #1: common_mutex --]
[-- Type: text/plain, Size: 19007 bytes --]

Use the mutex definition from SLAB and make it the common way to take a sleeping lock.

This has the effect of using a mutex instead of a rw semaphore for SLUB.

SLOB gains the use of a mutex for kmem_cache_create serialization.
Not needed now but SLOB may acquire some more features later (like slabinfo
/ sysfs support) through the expansion of the common code that will
need this.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |  108 +++++++++++++++++++++++++------------------------------
 mm/slab.h        |    4 ++
 mm/slab_common.c |    2 +
 mm/slub.c        |   54 ++++++++++++---------------
 4 files changed, 82 insertions(+), 86 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-07-06 07:30:16.719290474 -0500
+++ linux-2.6/mm/slab.c	2012-07-06 07:30:20.735290389 -0500
@@ -68,7 +68,7 @@
  * Further notes from the original documentation:
  *
  * 11 April '97.  Started multi-threading - markhe
- *	The global cache-chain is protected by the mutex 'cache_chain_mutex'.
+ *	The global cache-chain is protected by the mutex 'slab_mutex'.
  *	The sem is only needed when accessing/extending the cache-chain, which
  *	can never happen inside an interrupt (kmem_cache_create(),
  *	kmem_cache_shrink() and kmem_cache_reap()).
@@ -671,12 +671,6 @@ static void slab_set_debugobj_lock_class
 }
 #endif
 
-/*
- * Guard access to the cache-chain.
- */
-static DEFINE_MUTEX(cache_chain_mutex);
-static struct list_head cache_chain;
-
 static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
 
 static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -1100,7 +1094,7 @@ static inline int cache_free_alien(struc
  * When hotplugging memory or a cpu, existing nodelists are not replaced if
  * already in use.
  *
- * Must hold cache_chain_mutex.
+ * Must hold slab_mutex.
  */
 static int init_cache_nodelists_node(int node)
 {
@@ -1108,7 +1102,7 @@ static int init_cache_nodelists_node(int
 	struct kmem_list3 *l3;
 	const int memsize = sizeof(struct kmem_list3);
 
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		/*
 		 * Set up the size64 kmemlist for cpu before we can
 		 * begin anything. Make sure some other cpu on this
@@ -1124,7 +1118,7 @@ static int init_cache_nodelists_node(int
 
 			/*
 			 * The l3s don't come and go as CPUs come and
-			 * go.  cache_chain_mutex is sufficient
+			 * go.  slab_mutex is sufficient
 			 * protection here.
 			 */
 			cachep->nodelists[node] = l3;
@@ -1146,7 +1140,7 @@ static void __cpuinit cpuup_canceled(lon
 	int node = cpu_to_mem(cpu);
 	const struct cpumask *mask = cpumask_of_node(node);
 
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		struct array_cache *nc;
 		struct array_cache *shared;
 		struct array_cache **alien;
@@ -1196,7 +1190,7 @@ free_array_cache:
 	 * the respective cache's slabs,  now we can go ahead and
 	 * shrink each nodelist to its limit.
 	 */
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		l3 = cachep->nodelists[node];
 		if (!l3)
 			continue;
@@ -1225,7 +1219,7 @@ static int __cpuinit cpuup_prepare(long
 	 * Now we can go ahead with allocating the shared arrays and
 	 * array caches
 	 */
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		struct array_cache *nc;
 		struct array_cache *shared = NULL;
 		struct array_cache **alien = NULL;
@@ -1293,9 +1287,9 @@ static int __cpuinit cpuup_callback(stru
 	switch (action) {
 	case CPU_UP_PREPARE:
 	case CPU_UP_PREPARE_FROZEN:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		err = cpuup_prepare(cpu);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
@@ -1305,7 +1299,7 @@ static int __cpuinit cpuup_callback(stru
   	case CPU_DOWN_PREPARE:
   	case CPU_DOWN_PREPARE_FROZEN:
 		/*
-		 * Shutdown cache reaper. Note that the cache_chain_mutex is
+		 * Shutdown cache reaper. Note that the slab_mutex is
 		 * held so that if cache_reap() is invoked it cannot do
 		 * anything expensive but will only modify reap_work
 		 * and reschedule the timer.
@@ -1332,9 +1326,9 @@ static int __cpuinit cpuup_callback(stru
 #endif
 	case CPU_UP_CANCELED:
 	case CPU_UP_CANCELED_FROZEN:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		cpuup_canceled(cpu);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	}
 	return notifier_from_errno(err);
@@ -1350,14 +1344,14 @@ static struct notifier_block __cpuinitda
  * Returns -EBUSY if all objects cannot be drained so that the node is not
  * removed.
  *
- * Must hold cache_chain_mutex.
+ * Must hold slab_mutex.
  */
 static int __meminit drain_cache_nodelists_node(int node)
 {
 	struct kmem_cache *cachep;
 	int ret = 0;
 
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		struct kmem_list3 *l3;
 
 		l3 = cachep->nodelists[node];
@@ -1388,14 +1382,14 @@ static int __meminit slab_memory_callbac
 
 	switch (action) {
 	case MEM_GOING_ONLINE:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		ret = init_cache_nodelists_node(nid);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	case MEM_GOING_OFFLINE:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		ret = drain_cache_nodelists_node(nid);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	case MEM_ONLINE:
 	case MEM_OFFLINE:
@@ -1499,8 +1493,8 @@ void __init kmem_cache_init(void)
 	node = numa_mem_id();
 
 	/* 1) create the cache_cache */
-	INIT_LIST_HEAD(&cache_chain);
-	list_add(&cache_cache.list, &cache_chain);
+	INIT_LIST_HEAD(&slab_caches);
+	list_add(&cache_cache.list, &slab_caches);
 	cache_cache.colour_off = cache_line_size();
 	cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
 	cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
@@ -1642,11 +1636,11 @@ void __init kmem_cache_init_late(void)
 	init_lock_keys();
 
 	/* 6) resize the head arrays to their final sizes */
-	mutex_lock(&cache_chain_mutex);
-	list_for_each_entry(cachep, &cache_chain, list)
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(cachep, &slab_caches, list)
 		if (enable_cpucache(cachep, GFP_NOWAIT))
 			BUG();
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 
 	/* Done! */
 	slab_state = FULL;
@@ -2253,10 +2247,10 @@ __kmem_cache_create (const char *name, s
 	 */
 	if (slab_is_available()) {
 		get_online_cpus();
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 	}
 
-	list_for_each_entry(pc, &cache_chain, list) {
+	list_for_each_entry(pc, &slab_caches, list) {
 		char tmp;
 		int res;
 
@@ -2500,10 +2494,10 @@ __kmem_cache_create (const char *name, s
 	}
 
 	/* cache setup completed, link it into the list */
-	list_add(&cachep->list, &cache_chain);
+	list_add(&cachep->list, &slab_caches);
 oops:
 	if (slab_is_available()) {
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		put_online_cpus();
 	}
 	return cachep;
@@ -2622,7 +2616,7 @@ out:
 	return nr_freed;
 }
 
-/* Called with cache_chain_mutex held to protect against cpu hotplug */
+/* Called with slab_mutex held to protect against cpu hotplug */
 static int __cache_shrink(struct kmem_cache *cachep)
 {
 	int ret = 0, i = 0;
@@ -2657,9 +2651,9 @@ int kmem_cache_shrink(struct kmem_cache
 	BUG_ON(!cachep || in_interrupt());
 
 	get_online_cpus();
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	ret = __cache_shrink(cachep);
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	put_online_cpus();
 	return ret;
 }
@@ -2687,15 +2681,15 @@ void kmem_cache_destroy(struct kmem_cach
 
 	/* Find the cache in the chain of caches. */
 	get_online_cpus();
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	/*
 	 * the chain is never empty, cache_cache is never destroyed
 	 */
 	list_del(&cachep->list);
 	if (__cache_shrink(cachep)) {
 		slab_error(cachep, "Can't free all objects");
-		list_add(&cachep->list, &cache_chain);
-		mutex_unlock(&cache_chain_mutex);
+		list_add(&cachep->list, &slab_caches);
+		mutex_unlock(&slab_mutex);
 		put_online_cpus();
 		return;
 	}
@@ -2704,7 +2698,7 @@ void kmem_cache_destroy(struct kmem_cach
 		rcu_barrier();
 
 	__kmem_cache_destroy(cachep);
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	put_online_cpus();
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
@@ -4017,7 +4011,7 @@ static void do_ccupdate_local(void *info
 	new->new[smp_processor_id()] = old;
 }
 
-/* Always called with the cache_chain_mutex held */
+/* Always called with the slab_mutex held */
 static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
 				int batchcount, int shared, gfp_t gfp)
 {
@@ -4061,7 +4055,7 @@ static int do_tune_cpucache(struct kmem_
 	return alloc_kmemlist(cachep, gfp);
 }
 
-/* Called with cache_chain_mutex held always */
+/* Called with slab_mutex held always */
 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
 {
 	int err;
@@ -4163,11 +4157,11 @@ static void cache_reap(struct work_struc
 	int node = numa_mem_id();
 	struct delayed_work *work = to_delayed_work(w);
 
-	if (!mutex_trylock(&cache_chain_mutex))
+	if (!mutex_trylock(&slab_mutex))
 		/* Give up. Setup the next iteration. */
 		goto out;
 
-	list_for_each_entry(searchp, &cache_chain, list) {
+	list_for_each_entry(searchp, &slab_caches, list) {
 		check_irq_on();
 
 		/*
@@ -4205,7 +4199,7 @@ next:
 		cond_resched();
 	}
 	check_irq_on();
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	next_reap_node();
 out:
 	/* Set up the next iteration */
@@ -4241,21 +4235,21 @@ static void *s_start(struct seq_file *m,
 {
 	loff_t n = *pos;
 
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	if (!n)
 		print_slabinfo_header(m);
 
-	return seq_list_start(&cache_chain, *pos);
+	return seq_list_start(&slab_caches, *pos);
 }
 
 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 {
-	return seq_list_next(p, &cache_chain, pos);
+	return seq_list_next(p, &slab_caches, pos);
 }
 
 static void s_stop(struct seq_file *m, void *p)
 {
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 }
 
 static int s_show(struct seq_file *m, void *p)
@@ -4406,9 +4400,9 @@ static ssize_t slabinfo_write(struct fil
 		return -EINVAL;
 
 	/* Find the cache in the chain of caches. */
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	res = -EINVAL;
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		if (!strcmp(cachep->name, kbuf)) {
 			if (limit < 1 || batchcount < 1 ||
 					batchcount > limit || shared < 0) {
@@ -4421,7 +4415,7 @@ static ssize_t slabinfo_write(struct fil
 			break;
 		}
 	}
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	if (res >= 0)
 		res = count;
 	return res;
@@ -4444,8 +4438,8 @@ static const struct file_operations proc
 
 static void *leaks_start(struct seq_file *m, loff_t *pos)
 {
-	mutex_lock(&cache_chain_mutex);
-	return seq_list_start(&cache_chain, *pos);
+	mutex_lock(&slab_mutex);
+	return seq_list_start(&slab_caches, *pos);
 }
 
 static inline int add_caller(unsigned long *n, unsigned long v)
@@ -4544,17 +4538,17 @@ static int leaks_show(struct seq_file *m
 	name = cachep->name;
 	if (n[0] == n[1]) {
 		/* Increase the buffer size */
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		m->private = kzalloc(n[0] * 4 * sizeof(unsigned long), GFP_KERNEL);
 		if (!m->private) {
 			/* Too bad, we are really out */
 			m->private = n;
-			mutex_lock(&cache_chain_mutex);
+			mutex_lock(&slab_mutex);
 			return -ENOMEM;
 		}
 		*(unsigned long *)m->private = n[0] * 2;
 		kfree(n);
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		/* Now make sure this entry will be retried */
 		m->count = m->size;
 		return 0;
Index: linux-2.6/mm/slab.h
===================================================================
--- linux-2.6.orig/mm/slab.h	2012-07-06 07:30:16.719290474 -0500
+++ linux-2.6/mm/slab.h	2012-07-06 07:30:20.735290389 -0500
@@ -23,6 +23,10 @@ enum slab_state {
 
 extern enum slab_state slab_state;
 
+/* The slab cache mutex protects the management structures during changes */
+extern struct mutex slab_mutex;
+extern struct list_head slab_caches;
+
 struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *));
 
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-07-06 07:30:16.719290474 -0500
+++ linux-2.6/mm/slub.c	2012-07-06 07:30:20.735290389 -0500
@@ -36,13 +36,13 @@
 
 /*
  * Lock order:
- *   1. slub_lock (Global Semaphore)
+ *   1. slab_mutex (Global Mutex)
  *   2. node->list_lock
  *   3. slab_lock(page) (Only on some arches and for debugging)
  *
- *   slub_lock
+ *   slab_mutex
  *
- *   The role of the slub_lock is to protect the list of all the slabs
+ *   The role of the slab_mutex is to protect the list of all the slabs
  *   and to synchronize major metadata changes to slab cache structures.
  *
  *   The slab_lock is only used for debugging and on arches that do not
@@ -183,10 +183,6 @@ static int kmem_size = sizeof(struct kme
 static struct notifier_block slab_notifier;
 #endif
 
-/* A list of all slab caches on the system */
-static DECLARE_RWSEM(slub_lock);
-static LIST_HEAD(slab_caches);
-
 /*
  * Tracking user of a slab.
  */
@@ -3176,11 +3172,11 @@ static inline int kmem_cache_close(struc
  */
 void kmem_cache_destroy(struct kmem_cache *s)
 {
-	down_write(&slub_lock);
+	mutex_lock(&slab_mutex);
 	s->refcount--;
 	if (!s->refcount) {
 		list_del(&s->list);
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		if (kmem_cache_close(s)) {
 			printk(KERN_ERR "SLUB %s: %s called for cache that "
 				"still has objects.\n", s->name, __func__);
@@ -3190,7 +3186,7 @@ void kmem_cache_destroy(struct kmem_cach
 			rcu_barrier();
 		sysfs_slab_remove(s);
 	} else
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
 
@@ -3252,7 +3248,7 @@ static struct kmem_cache *__init create_
 
 	/*
 	 * This function is called with IRQs disabled during early-boot on
-	 * single CPU so there's no need to take slub_lock here.
+	 * single CPU so there's no need to take slab_mutex here.
 	 */
 	if (!kmem_cache_open(s, name, size, ARCH_KMALLOC_MINALIGN,
 								flags, NULL))
@@ -3537,10 +3533,10 @@ static int slab_mem_going_offline_callba
 {
 	struct kmem_cache *s;
 
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	list_for_each_entry(s, &slab_caches, list)
 		kmem_cache_shrink(s);
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 
 	return 0;
 }
@@ -3561,7 +3557,7 @@ static void slab_mem_offline_callback(vo
 	if (offline_node < 0)
 		return;
 
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	list_for_each_entry(s, &slab_caches, list) {
 		n = get_node(s, offline_node);
 		if (n) {
@@ -3577,7 +3573,7 @@ static void slab_mem_offline_callback(vo
 			kmem_cache_free(kmem_cache_node, n);
 		}
 	}
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 }
 
 static int slab_mem_going_online_callback(void *arg)
@@ -3600,7 +3596,7 @@ static int slab_mem_going_online_callbac
 	 * allocate a kmem_cache_node structure in order to bring the node
 	 * online.
 	 */
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	list_for_each_entry(s, &slab_caches, list) {
 		/*
 		 * XXX: kmem_cache_alloc_node will fallback to other nodes
@@ -3616,7 +3612,7 @@ static int slab_mem_going_online_callbac
 		s->node[nid] = n;
 	}
 out:
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 	return ret;
 }
 
@@ -3914,7 +3910,7 @@ struct kmem_cache *__kmem_cache_create(c
 	struct kmem_cache *s;
 	char *n;
 
-	down_write(&slub_lock);
+	mutex_lock(&slab_mutex);
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
 		s->refcount++;
@@ -3929,7 +3925,7 @@ struct kmem_cache *__kmem_cache_create(c
 			s->refcount--;
 			goto err;
 		}
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		return s;
 	}
 
@@ -3942,9 +3938,9 @@ struct kmem_cache *__kmem_cache_create(c
 		if (kmem_cache_open(s, n,
 				size, align, flags, ctor)) {
 			list_add(&s->list, &slab_caches);
-			up_write(&slub_lock);
+			mutex_unlock(&slab_mutex);
 			if (sysfs_slab_add(s)) {
-				down_write(&slub_lock);
+				mutex_lock(&slab_mutex);
 				list_del(&s->list);
 				kfree(n);
 				kfree(s);
@@ -3956,7 +3952,7 @@ struct kmem_cache *__kmem_cache_create(c
 	}
 	kfree(n);
 err:
-	up_write(&slub_lock);
+	mutex_unlock(&slab_mutex);
 	return s;
 }
 
@@ -3977,13 +3973,13 @@ static int __cpuinit slab_cpuup_callback
 	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		down_read(&slub_lock);
+		mutex_lock(&slab_mutex);
 		list_for_each_entry(s, &slab_caches, list) {
 			local_irq_save(flags);
 			__flush_cpu_slab(s, cpu);
 			local_irq_restore(flags);
 		}
-		up_read(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		break;
 	default:
 		break;
@@ -5359,11 +5355,11 @@ static int __init slab_sysfs_init(void)
 	struct kmem_cache *s;
 	int err;
 
-	down_write(&slub_lock);
+	mutex_lock(&slab_mutex);
 
 	slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
 	if (!slab_kset) {
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		printk(KERN_ERR "Cannot register slab subsystem.\n");
 		return -ENOSYS;
 	}
@@ -5388,7 +5384,7 @@ static int __init slab_sysfs_init(void)
 		kfree(al);
 	}
 
-	up_write(&slub_lock);
+	mutex_unlock(&slab_mutex);
 	resiliency_test();
 	return 0;
 }
@@ -5414,7 +5410,7 @@ static void *s_start(struct seq_file *m,
 {
 	loff_t n = *pos;
 
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	if (!n)
 		print_slabinfo_header(m);
 
@@ -5428,7 +5424,7 @@ static void *s_next(struct seq_file *m,
 
 static void s_stop(struct seq_file *m, void *p)
 {
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 }
 
 static int s_show(struct seq_file *m, void *p)
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-07-06 07:30:16.719290474 -0500
+++ linux-2.6/mm/slab_common.c	2012-07-06 07:30:20.735290389 -0500
@@ -19,6 +19,8 @@
 #include "slab.h"
 
 enum slab_state slab_state;
+LIST_HEAD(slab_caches);
+DEFINE_MUTEX(slab_mutex);
 
 /*
  * kmem_cache_create - Create a cache.

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Common [4/4] Move kmem_cache_create mutex handling to common code

[Christoph Lameter]

[-- Attachment #1: move_mutex_to_common --]
[-- Type: text/plain, Size: 5489 bytes --]

Move the mutex handling into the common kmem_cache_create()
function.

Then we can also move more checks out of SLAB's kmem_cache_create()
into the common code.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |   52 +---------------------------------------------------
 mm/slab_common.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 mm/slub.c        |   28 +++++++++++++---------------
 3 files changed, 54 insertions(+), 67 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-07-06 08:45:07.727197416 -0500
+++ linux-2.6/mm/slab.c	2012-07-06 09:16:53.211157934 -0500
@@ -2228,55 +2228,10 @@ __kmem_cache_create (const char *name, s
 	unsigned long flags, void (*ctor)(void *))
 {
 	size_t left_over, slab_size, ralign;
-	struct kmem_cache *cachep = NULL, *pc;
+	struct kmem_cache *cachep = NULL;
 	gfp_t gfp;
 
-	/*
-	 * Sanity checks... these are all serious usage bugs.
-	 */
-	if (!name || in_interrupt() || (size < BYTES_PER_WORD) ||
-	    size > KMALLOC_MAX_SIZE) {
-		printk(KERN_ERR "%s: Early error in slab %s\n", __func__,
-				name);
-		BUG();
-	}
-
-	/*
-	 * We use cache_chain_mutex to ensure a consistent view of
-	 * cpu_online_mask as well.  Please see cpuup_callback
-	 */
-	if (slab_is_available()) {
-		get_online_cpus();
-		mutex_lock(&slab_mutex);
-	}
-
-	list_for_each_entry(pc, &slab_caches, list) {
-		char tmp;
-		int res;
-
-		/*
-		 * This happens when the module gets unloaded and doesn't
-		 * destroy its slab cache and no-one else reuses the vmalloc
-		 * area of the module.  Print a warning.
-		 */
-		res = probe_kernel_address(pc->name, tmp);
-		if (res) {
-			printk(KERN_ERR
-			       "SLAB: cache with size %d has lost its name\n",
-			       pc->size);
-			continue;
-		}
-
-		if (!strcmp(pc->name, name)) {
-			printk(KERN_ERR
-			       "kmem_cache_create: duplicate cache %s\n", name);
-			dump_stack();
-			goto oops;
-		}
-	}
-
 #if DEBUG
-	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
 #if FORCED_DEBUG
 	/*
 	 * Enable redzoning and last user accounting, except for caches with
@@ -2495,11 +2450,6 @@ __kmem_cache_create (const char *name, s
 
 	/* cache setup completed, link it into the list */
 	list_add(&cachep->list, &slab_caches);
-oops:
-	if (slab_is_available()) {
-		mutex_unlock(&slab_mutex);
-		put_online_cpus();
-	}
 	return cachep;
 }
 
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-07-06 08:45:07.727197416 -0500
+++ linux-2.6/mm/slab_common.c	2012-07-06 09:16:53.235157935 -0500
@@ -11,7 +11,8 @@
 #include <linux/memory.h>
 #include <linux/compiler.h>
 #include <linux/module.h>
-
+#include <linux/cpu.h>
+#include <linux/uaccess.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/page.h>
@@ -61,8 +62,46 @@ struct kmem_cache *kmem_cache_create(con
 	}
 #endif
 
+	get_online_cpus();
+	mutex_lock(&slab_mutex);
+
+#ifdef CONFIG_DEBUG_VM
+	list_for_each_entry(s, &slab_caches, list) {
+		char tmp;
+		int res;
+
+		/*
+		 * This happens when the module gets unloaded and doesn't
+		 * destroy its slab cache and no-one else reuses the vmalloc
+		 * area of the module.  Print a warning.
+		 */
+		res = probe_kernel_address(s->name, tmp);
+		if (res) {
+			printk(KERN_ERR
+			       "Slab cache with size %d has lost its name\n",
+			       s->object_size);
+			continue;
+		}
+
+		if (!strcmp(s->name, name)) {
+			printk(KERN_ERR "kmem_cache_create(%s): Cache name"
+				" already exists.\n",
+				name);
+			dump_stack();
+			s = NULL;
+			goto oops;
+		}
+	}
+
+	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
+#endif
+
 	s = __kmem_cache_create(name, size, align, flags, ctor);
 
+oops:
+	mutex_unlock(&slab_mutex);
+	put_online_cpus();
+
 #ifdef CONFIG_DEBUG_VM
 out:
 #endif
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-07-06 08:45:07.727197416 -0500
+++ linux-2.6/mm/slub.c	2012-07-06 09:16:53.223157935 -0500
@@ -3910,7 +3910,6 @@ struct kmem_cache *__kmem_cache_create(c
 	struct kmem_cache *s;
 	char *n;
 
-	mutex_lock(&slab_mutex);
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
 		s->refcount++;
@@ -3923,37 +3922,36 @@ struct kmem_cache *__kmem_cache_create(c
 
 		if (sysfs_slab_alias(s, name)) {
 			s->refcount--;
-			goto err;
+			return NULL;
 		}
-		mutex_unlock(&slab_mutex);
 		return s;
 	}
 
 	n = kstrdup(name, GFP_KERNEL);
 	if (!n)
-		goto err;
+		return NULL;
 
 	s = kmalloc(kmem_size, GFP_KERNEL);
 	if (s) {
 		if (kmem_cache_open(s, n,
 				size, align, flags, ctor)) {
+			int r;
+
 			list_add(&s->list, &slab_caches);
 			mutex_unlock(&slab_mutex);
-			if (sysfs_slab_add(s)) {
-				mutex_lock(&slab_mutex);
-				list_del(&s->list);
-				kfree(n);
-				kfree(s);
-				goto err;
-			}
-			return s;
+			r = sysfs_slab_add(s);
+			mutex_lock(&slab_mutex);
+
+			if (!r)
+				return s;
+
+			list_del(&s->list);
+			kmem_cache_close(s);
 		}
 		kfree(s);
 	}
 	kfree(n);
-err:
-	mutex_unlock(&slab_mutex);
-	return s;
+	return NULL;
 }
 
 #ifdef CONFIG_SMP

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Re: Common [0/4] Sl[auo]b: Common code rework V6 (limited)

[Pekka Enberg]

On Fri, Jul 6, 2012 at 11:25 PM, Christoph Lameter <cl@linux.com> wrote:
> This is a series of patches that extracts common functionality from
> slab allocators into a common code base. The intend is to standardize
> as much as possible of the allocator behavior while keeping the
> distinctive features of each allocator which are mostly due to their
> storage format and serialization approaches.

Works fine here. David, Glauber, does the series look OK to move forward with?

                        Pekka

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Re: Common [0/4] Sl[auo]b: Common code rework V6 (limited)

[Glauber Costa]

On 07/06/2012 05:25 PM, Christoph Lameter wrote:
> 
> V5->V6:
> - Patches against Pekka's for-next tree.
> - Go slow and cut down to just patches that are safe
>   (there will likely be some churn already due to the
>   mutex unification between slabs)
> - More to come next week when I have more time (
>   took me almost the whole week to catch up after
>   being gone for awhile).
> 
> V4->V5
> - Rediff against current upstream + Pekka's cleanup branch.
> 
> V3->V4:
> - Do not use the COMMON macro anymore.
> - Fixup various issues
> - No general sysfs support yet due to lockdep issues with
>   keys in kmalloc'ed memory.
> 
> V2->V3:
> - Incorporate more feedback from Joonsoo Kim and Glauber Costa
> - And a couple more patches to deal with slab duping and move
>   more code to slab_common.c
> 
> V1->V2:
> - Incorporate glommers feedback.
> - Add 2 more patches dealing with common code in kmem_cache_destroy
> 

This series has the warning problem on oops label that I've already told
you about. But it seems this is already known by now =)

Sorry, just back from vacations.


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