Commit f0188f47 authored by Ravikiran G Thirumalai's avatar Ravikiran G Thirumalai Committed by Linus Torvalds

[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: default avatarRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: default avatarShai Fultheim <shai@scalex86.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8e36709d
......@@ -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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