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/slab.c b/mm/slab.c
index e74a16e..5241b65 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2547,7 +2547,7 @@
}
if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
- synchronize_rcu();
+ rcu_barrier();
__kmem_cache_destroy(cachep);
mutex_unlock(&cache_chain_mutex);