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-rw-r--r--mm/slab.c40
1 files changed, 21 insertions, 19 deletions
diff --git a/mm/slab.c b/mm/slab.c
index ff60a94..3318252 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -730,7 +730,10 @@ static inline void init_lock_keys(void)
}
#endif
-/* Guard access to the cache-chain. */
+/*
+ * 1. Guard access to the cache-chain.
+ * 2. Protect sanity of cpu_online_map against cpu hotplug events
+ */
static DEFINE_MUTEX(cache_chain_mutex);
static struct list_head cache_chain;
@@ -1230,12 +1233,18 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
kfree(shared);
free_alien_cache(alien);
}
- mutex_unlock(&cache_chain_mutex);
break;
case CPU_ONLINE:
+ mutex_unlock(&cache_chain_mutex);
start_cpu_timer(cpu);
break;
#ifdef CONFIG_HOTPLUG_CPU
+ case CPU_DOWN_PREPARE:
+ mutex_lock(&cache_chain_mutex);
+ break;
+ case CPU_DOWN_FAILED:
+ mutex_unlock(&cache_chain_mutex);
+ break;
case CPU_DEAD:
/*
* Even if all the cpus of a node are down, we don't free the
@@ -1246,8 +1255,8 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
* gets destroyed at kmem_cache_destroy().
*/
/* fall thru */
+#endif
case CPU_UP_CANCELED:
- mutex_lock(&cache_chain_mutex);
list_for_each_entry(cachep, &cache_chain, next) {
struct array_cache *nc;
struct array_cache *shared;
@@ -1308,11 +1317,9 @@ free_array_cache:
}
mutex_unlock(&cache_chain_mutex);
break;
-#endif
}
return NOTIFY_OK;
bad:
- mutex_unlock(&cache_chain_mutex);
return NOTIFY_BAD;
}
@@ -2098,11 +2105,9 @@ kmem_cache_create (const char *name, size_t size, size_t align,
}
/*
- * Prevent CPUs from coming and going.
- * lock_cpu_hotplug() nests outside cache_chain_mutex
+ * We use cache_chain_mutex to ensure a consistent view of
+ * cpu_online_map as well. Please see cpuup_callback
*/
- lock_cpu_hotplug();
-
mutex_lock(&cache_chain_mutex);
list_for_each_entry(pc, &cache_chain, next) {
@@ -2325,7 +2330,6 @@ oops:
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);
@@ -2443,6 +2447,7 @@ out:
return nr_freed;
}
+/* Called with cache_chain_mutex held to protect against cpu hotplug */
static int __cache_shrink(struct kmem_cache *cachep)
{
int ret = 0, i = 0;
@@ -2473,9 +2478,13 @@ static int __cache_shrink(struct kmem_cache *cachep)
*/
int kmem_cache_shrink(struct kmem_cache *cachep)
{
+ int ret;
BUG_ON(!cachep || in_interrupt());
- return __cache_shrink(cachep);
+ mutex_lock(&cache_chain_mutex);
+ ret = __cache_shrink(cachep);
+ mutex_unlock(&cache_chain_mutex);
+ return ret;
}
EXPORT_SYMBOL(kmem_cache_shrink);
@@ -2499,23 +2508,16 @@ void kmem_cache_destroy(struct kmem_cache *cachep)
{
BUG_ON(!cachep || in_interrupt());
- /* Don't let CPUs to come and go */
- lock_cpu_hotplug();
-
/* Find the cache in the chain of caches. */
mutex_lock(&cache_chain_mutex);
/*
* the chain is never empty, cache_cache is never destroyed
*/
list_del(&cachep->next);
- mutex_unlock(&cache_chain_mutex);
-
if (__cache_shrink(cachep)) {
slab_error(cachep, "Can't free all objects");
- mutex_lock(&cache_chain_mutex);
list_add(&cachep->next, &cache_chain);
mutex_unlock(&cache_chain_mutex);
- unlock_cpu_hotplug();
return;
}
@@ -2523,7 +2525,7 @@ void kmem_cache_destroy(struct kmem_cache *cachep)
synchronize_rcu();
__kmem_cache_destroy(cachep);
- unlock_cpu_hotplug();
+ mutex_unlock(&cache_chain_mutex);
}
EXPORT_SYMBOL(kmem_cache_destroy);