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[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>
This commit is contained in:
Ravikiran G Thirumalai 2006-02-10 01:51:13 -08:00 committed by Linus Torvalds
parent 8e36709d8c
commit f0188f4748
1 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
mm/slab.c
View File

@ -1717,6 +1717,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
BUG(); BUG();
} }
/*
* Prevent CPUs from coming and going.
* lock_cpu_hotplug() nests outside cache_chain_mutex
*/
lock_cpu_hotplug();
mutex_lock(&cache_chain_mutex); mutex_lock(&cache_chain_mutex);
list_for_each(p, &cache_chain) { 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->dtor = dtor;
cachep->name = name; cachep->name = name;
/* Don't let CPUs to come and go */
lock_cpu_hotplug();
if (g_cpucache_up == FULL) { if (g_cpucache_up == FULL) {
enable_cpucache(cachep); 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 */ /* cache setup completed, link it into the list */
list_add(&cachep->next, &cache_chain); list_add(&cachep->next, &cache_chain);
unlock_cpu_hotplug();
oops: oops:
if (!cachep && (flags & SLAB_PANIC)) if (!cachep && (flags & SLAB_PANIC))
panic("kmem_cache_create(): failed to create slab `%s'\n", panic("kmem_cache_create(): failed to create slab `%s'\n",
name); name);
mutex_unlock(&cache_chain_mutex); mutex_unlock(&cache_chain_mutex);
unlock_cpu_hotplug();
return cachep; return cachep;
} }
EXPORT_SYMBOL(kmem_cache_create); EXPORT_SYMBOL(kmem_cache_create);