* [patch] slab: Avoid deadlock at kmem_cache_create/kmem_cache_destroy
@ 2006-02-09 18:29 Ravikiran G Thirumalai
2006-02-10 7:55 ` Pekka J Enberg
0 siblings, 1 reply; 2+ messages in thread
From: Ravikiran G Thirumalai @ 2006-02-09 18:29 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-kernel, Christoph Lameter, Manfred Spraul, vatsa, penberg,
Shai Fultheim (Shai@scalex86.org)
Prevents deadlock situation between kmem_cache_create()/kmem_cache_destory(),
and kmem_cache_create() /cpu hotplug. The locking order probably got
moved over time.
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c 2006-02-08 13:13:23.000000000 -0800
+++ linux-2.6/mm/slab.c 2006-02-09 01:58:02.000000000 -0800
@@ -1718,6 +1718,13 @@ kmem_cache_create (const char *name, siz
BUG();
}
+ /*
+ * Don't let CPUs to come and go.
+ * Note: preserve lock taking order -- lock_cpu_hotplug first,
+ * cache_chain_mutex then.
+ */
+ lock_cpu_hotplug();
+
mutex_lock(&cache_chain_mutex);
list_for_each(p, &cache_chain) {
@@ -1918,8 +1925,6 @@ kmem_cache_create (const char *name, siz
cachep->dtor = dtor;
cachep->name = name;
- /* Don't let CPUs to come and go */
- lock_cpu_hotplug();
if (g_cpucache_up == FULL) {
enable_cpucache(cachep);
@@ -1978,12 +1983,12 @@ kmem_cache_create (const char *name, siz
/* cache setup completed, link it into the list */
list_add(&cachep->next, &cache_chain);
- unlock_cpu_hotplug();
oops:
if (!cachep && (flags & SLAB_PANIC))
panic("kmem_cache_create(): failed to create slab `%s'\n",
name);
mutex_unlock(&cache_chain_mutex);
+ unlock_cpu_hotplug();
return cachep;
}
EXPORT_SYMBOL(kmem_cache_create);
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2006-02-09 18:29 [patch] slab: Avoid deadlock at kmem_cache_create/kmem_cache_destroy Ravikiran G Thirumalai
2006-02-10 7:55 ` Pekka J Enberg
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