Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
  slab, kmemleak: pass the correct pointer to kmemleak_erase()
  slab, kmemleak: stop calling kmemleak_erase() unconditionally
  SLAB: Fix unlikely() annotation in __cache_alloc_node()
  SLAB: Fix lockdep annotations for CPU hotplug
  SLUB: Fix __GFP_ZERO unlikely() annotation
  slub: allow stats to be cleared

3 files changed, 145 insertions, 102 deletions

diff --git a/Documentation/ABI/testing/sysfs-kernel-slab b/Documentation/ABI/testing/sysfs-kernel-slab
index 6dcf75e594f..8b093f8222d 100644
--- a/Documentation/ABI/testing/sysfs-kernel-slab
+++ b/Documentation/ABI/testing/sysfs-kernel-slab
@@ -45,8 +45,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The alloc_fastpath file is read-only and specifies how many
-		objects have been allocated using the fast path.
+		The alloc_fastpath file shows how many objects have been
+		allocated using the fast path.  It can be written to clear the
+		current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/alloc_from_partial
@@ -55,9 +56,10 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The alloc_from_partial file is read-only and specifies how
-		many times a cpu slab has been full and it has been refilled
-		by using a slab from the list of partially used slabs.
+		The alloc_from_partial file shows how many times a cpu slab has
+		been full and it has been refilled by using a slab from the list
+		of partially used slabs.  It can be written to clear the current
+		count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/alloc_refill
@@ -66,9 +68,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The alloc_refill file is read-only and specifies how many
-		times the per-cpu freelist was empty but there were objects
-		available as the result of remote cpu frees.
+		The alloc_refill file shows how many times the per-cpu freelist
+		was empty but there were objects available as the result of
+		remote cpu frees.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/alloc_slab
@@ -77,8 +79,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The alloc_slab file is read-only and specifies how many times
-		a new slab had to be allocated from the page allocator.
+		The alloc_slab file is shows how many times a new slab had to
+		be allocated from the page allocator.  It can be written to
+		clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/alloc_slowpath
@@ -87,9 +90,10 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The alloc_slowpath file is read-only and specifies how many
-		objects have been allocated using the slow path because of a
-		refill or allocation from a partial or new slab.
+		The alloc_slowpath file shows how many objects have been
+		allocated using the slow path because of a refill or
+		allocation from a partial or new slab.  It can be written to
+		clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/cache_dma
@@ -117,10 +121,11 @@ KernelVersion:	2.6.31
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file cpuslab_flush is read-only and specifies how many
-		times a cache's cpu slabs have been flushed as the result of
-		destroying or shrinking a cache, a cpu going offline, or as
-		the result of forcing an allocation from a certain node.
+		The file cpuslab_flush shows how many times a cache's cpu slabs
+		have been flushed as the result of destroying or shrinking a
+		cache, a cpu going offline, or as the result of forcing an
+		allocation from a certain node.  It can be written to clear the
+		current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/ctor
@@ -139,8 +144,8 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file deactivate_empty is read-only and specifies how many
-		times an empty cpu slab was deactivated.
+		The deactivate_empty file shows how many times an empty cpu slab
+		was deactivated.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/deactivate_full
@@ -149,8 +154,8 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file deactivate_full is read-only and specifies how many
-		times a full cpu slab was deactivated.
+		The deactivate_full file shows how many times a full cpu slab
+		was deactivated.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/deactivate_remote_frees
@@ -159,9 +164,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file deactivate_remote_frees is read-only and specifies how
-		many times a cpu slab has been deactivated and contained free
-		objects that were freed remotely.
+		The deactivate_remote_frees file shows how many times a cpu slab
+		has been deactivated and contained free objects that were freed
+		remotely.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/deactivate_to_head
@@ -170,9 +175,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file deactivate_to_head is read-only and specifies how
-		many times a partial cpu slab was deactivated and added to the
-		head of its node's partial list.
+		The deactivate_to_head file shows how many times a partial cpu
+		slab was deactivated and added to the head of its node's partial
+		list.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/deactivate_to_tail
@@ -181,9 +186,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file deactivate_to_tail is read-only and specifies how
-		many times a partial cpu slab was deactivated and added to the
-		tail of its node's partial list.
+		The deactivate_to_tail file shows how many times a partial cpu
+		slab was deactivated and added to the tail of its node's partial
+		list.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/destroy_by_rcu
@@ -201,9 +206,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file free_add_partial is read-only and specifies how many
-		times an object has been freed in a full slab so that it had to
-		added to its node's partial list.
+		The free_add_partial file shows how many times an object has
+		been freed in a full slab so that it had to added to its node's
+		partial list.  It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/free_calls
@@ -222,9 +227,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The free_fastpath file is read-only and specifies how many
-		objects have been freed using the fast path because it was an
-		object from the cpu slab.
+		The free_fastpath file shows how many objects have been freed
+		using the fast path because it was an object from the cpu slab.
+		It can be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/free_frozen
@@ -233,9 +238,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The free_frozen file is read-only and specifies how many
-		objects have been freed to a frozen slab (i.e. a remote cpu
-		slab).
+		The free_frozen file shows how many objects have been freed to
+		a frozen slab (i.e. a remote cpu slab).  It can be written to
+		clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/free_remove_partial
@@ -244,9 +249,10 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file free_remove_partial is read-only and specifies how
-		many times an object has been freed to a now-empty slab so
-		that it had to be removed from its node's partial list.
+		The free_remove_partial file shows how many times an object has
+		been freed to a now-empty slab so that it had to be removed from
+		its node's partial list.  It can be written to clear the current
+		count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/free_slab
@@ -255,8 +261,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The free_slab file is read-only and specifies how many times an
-		empty slab has been freed back to the page allocator.
+		The free_slab file shows how many times an empty slab has been
+		freed back to the page allocator.  It can be written to clear
+		the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/free_slowpath
@@ -265,9 +272,9 @@ KernelVersion:	2.6.25
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The free_slowpath file is read-only and specifies how many
-		objects have been freed using the slow path (i.e. to a full or
-		partial slab).
+		The free_slowpath file shows how many objects have been freed
+		using the slow path (i.e. to a full or partial slab).  It can
+		be written to clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/hwcache_align
@@ -346,10 +353,10 @@ KernelVersion:	2.6.26
 Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
-		The file order_fallback is read-only and specifies how many
-		times an allocation of a new slab has not been possible at the
-		cache's order and instead fallen back to its minimum possible
-		order.
+		The order_fallback file shows how many times an allocation of a
+		new slab has not been possible at the cache's order and instead
+		fallen back to its minimum possible order.  It can be written to
+		clear the current count.
 		Available when CONFIG_SLUB_STATS is enabled.
 
 What:		/sys/kernel/slab/cache/partial
diff --git a/mm/slab.c b/mm/slab.c
index 7dfa481c96b..a6c9166996a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -604,6 +604,26 @@ 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,
+	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
 
 /*
@@ -620,40 +640,52 @@ static struct kmem_cache cache_cache = {
 static struct lock_class_key on_slab_l3_key;
 static struct lock_class_key on_slab_alc_key;
 
-static inline void init_lock_keys(void)
-
+static void init_node_lock_keys(int q)
 {
-	int q;
 	struct cache_sizes *s = malloc_sizes;
 
-	while (s->cs_size != ULONG_MAX) {
-		for_each_node(q) {
-			struct array_cache **alc;
-			int r;
-			struct kmem_list3 *l3 = s->cs_cachep->nodelists[q];
-			if (!l3 || OFF_SLAB(s->cs_cachep))
-				continue;
-			lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
-			alc = l3->alien;
-			/*
-			 * FIXME: This check for BAD_ALIEN_MAGIC
-			 * should go away when common slab code is taught to
-			 * work even without alien caches.
-			 * Currently, non NUMA code returns BAD_ALIEN_MAGIC
-			 * for alloc_alien_cache,
-			 */
-			if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
-				continue;
-			for_each_node(r) {
-				if (alc[r])
-					lockdep_set_class(&alc[r]->lock,
-					     &on_slab_alc_key);
-			}
+	if (g_cpucache_up != FULL)
+		return;
+
+	for (s = malloc_sizes; s->cs_size != ULONG_MAX; s++) {
+		struct array_cache **alc;
+		struct kmem_list3 *l3;
+		int r;
+
+		l3 = s->cs_cachep->nodelists[q];
+		if (!l3 || OFF_SLAB(s->cs_cachep))
+			return;
+		lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
+		alc = l3->alien;
+		/*
+		 * FIXME: This check for BAD_ALIEN_MAGIC
+		 * should go away when common slab code is taught to
+		 * work even without alien caches.
+		 * Currently, non NUMA code returns BAD_ALIEN_MAGIC
+		 * for alloc_alien_cache,
+		 */
+		if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
+			return;
+		for_each_node(r) {
+			if (alc[r])
+				lockdep_set_class(&alc[r]->lock,
+					&on_slab_alc_key);
 		}
-		s++;
 	}
 }
+
+static inline void init_lock_keys(void)
+{
+	int node;
+
+	for_each_node(node)
+		init_node_lock_keys(node);
+}
 #else
+static void init_node_lock_keys(int q)
+{
+}
+
 static inline void init_lock_keys(void)
 {
 }
@@ -665,26 +697,6 @@ static inline void init_lock_keys(void)
 static DEFINE_MUTEX(cache_chain_mutex);
 static struct list_head cache_chain;
 
-/*
- * chicken and egg problem: delay the per-cpu array allocation
- * until the general caches are up.
- */
-static enum {
-	NONE,
-	PARTIAL_AC,
-	PARTIAL_L3,
-	EARLY,
-	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;
-}
-
 static DEFINE_PER_CPU(struct delayed_work, reap_work);
 
 static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -1254,6 +1266,8 @@ static int __cpuinit cpuup_prepare(long cpu)
 		kfree(shared);
 		free_alien_cache(alien);
 	}
+	init_node_lock_keys(node);
+
 	return 0;
 bad:
 	cpuup_canceled(cpu);
@@ -3103,13 +3117,19 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 	} else {
 		STATS_INC_ALLOCMISS(cachep);
 		objp = cache_alloc_refill(cachep, flags);
+		/*
+		 * the 'ac' may be updated by cache_alloc_refill(),
+		 * and kmemleak_erase() requires its correct value.
+		 */
+		ac = cpu_cache_get(cachep);
 	}
 	/*
 	 * To avoid a false negative, if an object that is in one of the
 	 * per-CPU caches is leaked, we need to make sure kmemleak doesn't
 	 * treat the array pointers as a reference to the object.
 	 */
-	kmemleak_erase(&ac->entry[ac->avail]);
+	if (objp)
+		kmemleak_erase(&ac->entry[ac->avail]);
 	return objp;
 }
 
@@ -3306,7 +3326,7 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
 	cache_alloc_debugcheck_before(cachep, flags);
 	local_irq_save(save_flags);
 
-	if (unlikely(nodeid == -1))
+	if (nodeid == -1)
 		nodeid = numa_node_id();
 
 	if (unlikely(!cachep->nodelists[nodeid])) {
diff --git a/mm/slub.c b/mm/slub.c
index 4996fc71955..da0ce55965d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1735,7 +1735,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 	}
 	local_irq_restore(flags);
 
-	if (unlikely((gfpflags & __GFP_ZERO) && object))
+	if (unlikely(gfpflags & __GFP_ZERO) && object)
 		memset(object, 0, objsize);
 
 	kmemcheck_slab_alloc(s, gfpflags, object, c->objsize);
@@ -4371,12 +4371,28 @@ static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
 	return len + sprintf(buf + len, "\n");
 }
 
+static void clear_stat(struct kmem_cache *s, enum stat_item si)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		get_cpu_slab(s, cpu)->stat[si] = 0;
+}
+
 #define STAT_ATTR(si, text) 					\
 static ssize_t text##_show(struct kmem_cache *s, char *buf)	\
 {								\
 	return show_stat(s, buf, si);				\
 }								\
-SLAB_ATTR_RO(text);						\
+static ssize_t text##_store(struct kmem_cache *s,		\
+				const char *buf, size_t length)	\
+{								\
+	if (buf[0] != '0')					\
+		return -EINVAL;					\
+	clear_stat(s, si);					\
+	return length;						\
+}								\
+SLAB_ATTR(text);						\
 
 STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
 STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);