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Date: Fri, 14 Feb 2014 15:57:23 +0900
From: Joonsoo Kim <iamjoonsoo.kim@....com>
To: Pekka Enberg <penberg@...nel.org>
Cc: Christoph Lameter <cl@...ux.com>,
Andrew Morton <akpm@...ux-foundation.org>,
David Rientjes <rientjes@...gle.com>,
Wanpeng Li <liwanp@...ux.vnet.ibm.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Joonsoo Kim <js1304@...il.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH 9/9] slab: remove a useless lockdep annotation
Now, there is no code to hold two lock simultaneously, since
we don't call slab_destroy() with holding any lock. So, lockdep
annotation is useless now. Remove it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
diff --git a/mm/slab.c b/mm/slab.c
index 9c9d4d4..f723a72 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -437,143 +437,6 @@ static struct kmem_cache kmem_cache_boot = {
.name = "kmem_cache",
};
-#define BAD_ALIEN_MAGIC 0x01020304ul
-
-#ifdef CONFIG_LOCKDEP
-
-/*
- * Slab sometimes uses the kmalloc slabs to store the slab headers
- * for other slabs "off slab".
- * The locking for this is tricky in that it nests within the locks
- * of all other slabs in a few places; to deal with this special
- * locking we put on-slab caches into a separate lock-class.
- *
- * We set lock class for alien array caches which are up during init.
- * The lock annotation will be lost if all cpus of a node goes down and
- * then comes back up during hotplug
- */
-static struct lock_class_key on_slab_l3_key;
-static struct lock_class_key on_slab_alc_key;
-
-static struct lock_class_key debugobj_l3_key;
-static struct lock_class_key debugobj_alc_key;
-
-static void slab_set_lock_classes(struct kmem_cache *cachep,
- struct lock_class_key *l3_key, struct lock_class_key *alc_key,
- int q)
-{
- struct alien_cache **alc;
- struct kmem_cache_node *n;
- int r;
-
- n = cachep->node[q];
- if (!n)
- return;
-
- lockdep_set_class(&n->list_lock, l3_key);
- alc = n->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), alc_key);
- }
-}
-
-static void slab_set_debugobj_lock_classes_node(struct kmem_cache *cachep, int node)
-{
- slab_set_lock_classes(cachep, &debugobj_l3_key, &debugobj_alc_key, node);
-}
-
-static void slab_set_debugobj_lock_classes(struct kmem_cache *cachep)
-{
- int node;
-
- for_each_online_node(node)
- slab_set_debugobj_lock_classes_node(cachep, node);
-}
-
-static void init_node_lock_keys(int q)
-{
- int i;
-
- if (slab_state < UP)
- return;
-
- for (i = 1; i <= KMALLOC_SHIFT_HIGH; i++) {
- struct kmem_cache_node *n;
- struct kmem_cache *cache = kmalloc_caches[i];
-
- if (!cache)
- continue;
-
- n = cache->node[q];
- if (!n || OFF_SLAB(cache))
- continue;
-
- slab_set_lock_classes(cache, &on_slab_l3_key,
- &on_slab_alc_key, q);
- }
-}
-
-static void on_slab_lock_classes_node(struct kmem_cache *cachep, int q)
-{
- if (!cachep->node[q])
- return;
-
- slab_set_lock_classes(cachep, &on_slab_l3_key,
- &on_slab_alc_key, q);
-}
-
-static inline void on_slab_lock_classes(struct kmem_cache *cachep)
-{
- int node;
-
- VM_BUG_ON(OFF_SLAB(cachep));
- for_each_node(node)
- on_slab_lock_classes_node(cachep, node);
-}
-
-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)
-{
-}
-
-static inline void on_slab_lock_classes(struct kmem_cache *cachep)
-{
-}
-
-static inline void on_slab_lock_classes_node(struct kmem_cache *cachep, int node)
-{
-}
-
-static void slab_set_debugobj_lock_classes_node(struct kmem_cache *cachep, int node)
-{
-}
-
-static void slab_set_debugobj_lock_classes(struct kmem_cache *cachep)
-{
-}
-#endif
-
static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -921,7 +784,7 @@ static int transfer_objects(struct array_cache *to,
static inline struct alien_cache **alloc_alien_cache(int node,
int limit, gfp_t gfp)
{
- return (struct alien_cache **)BAD_ALIEN_MAGIC;
+ return NULL;
}
static inline void free_alien_cache(struct alien_cache **ac_ptr)
@@ -1296,13 +1159,7 @@ static int cpuup_prepare(long cpu)
spin_unlock_irq(&n->list_lock);
kfree(shared);
free_alien_cache(alien);
- if (cachep->flags & SLAB_DEBUG_OBJECTS)
- slab_set_debugobj_lock_classes_node(cachep, node);
- else if (!OFF_SLAB(cachep) &&
- !(cachep->flags & SLAB_DESTROY_BY_RCU))
- on_slab_lock_classes_node(cachep, node);
}
- init_node_lock_keys(node);
return 0;
bad:
@@ -1611,9 +1468,6 @@ void __init kmem_cache_init_late(void)
BUG();
mutex_unlock(&slab_mutex);
- /* Annotate slab for lockdep -- annotate the malloc caches */
- init_lock_keys();
-
/* Done! */
slab_state = FULL;
@@ -2386,17 +2240,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
return err;
}
- if (flags & SLAB_DEBUG_OBJECTS) {
- /*
- * Would deadlock through slab_destroy()->call_rcu()->
- * debug_object_activate()->kmem_cache_alloc().
- */
- WARN_ON_ONCE(flags & SLAB_DESTROY_BY_RCU);
-
- slab_set_debugobj_lock_classes(cachep);
- } else if (!OFF_SLAB(cachep) && !(flags & SLAB_DESTROY_BY_RCU))
- on_slab_lock_classes(cachep);
-
return 0;
}
--
1.7.9.5
--
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