fix RCU-callback-after-kmem_cache_destroy problem in sl[aou]b
Jesper noted that kmem_cache_destroy() invokes synchronize_rcu() rather than
rcu_barrier() in the SLAB_DESTROY_BY_RCU case, which could result in RCU
callbacks accessing a kmem_cache after it had been destroyed.
Cc: <stable@kernel.org>
Acked-by: Matt Mackall <mpm@selenic.com>
Reported-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/mm/slub.c b/mm/slub.c
index 819f056..a9201d8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2595,6 +2595,8 @@
*/
void kmem_cache_destroy(struct kmem_cache *s)
{
+ if (s->flags & SLAB_DESTROY_BY_RCU)
+ rcu_barrier();
down_write(&slub_lock);
s->refcount--;
if (!s->refcount) {