From f0188f47482efdbd2e005103bb4f0224a835dfad Mon Sep 17 00:00:00 2001
From: Ravikiran G Thirumalai <kiran@scalex86.org>
Date: Fri, 10 Feb 2006 01:51:13 -0800
Subject: [PATCH] [PATCH] slab: Avoid deadlock at
kmem_cache_create/kmem_cache_destroy
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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
mm/slab.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index d66c2b0d9715..add05d808a4a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1717,6 +1717,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
BUG();
}
+ /*
+ * Prevent CPUs from coming and going.
+ * lock_cpu_hotplug() nests outside cache_chain_mutex
+ */
+ lock_cpu_hotplug();
+
mutex_lock(&cache_chain_mutex);
list_for_each(p, &cache_chain) {
@@ -1918,8 +1924,6 @@ kmem_cache_create (const char *name, size_t size, size_t align,
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 +1982,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
/* 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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