From 7ed9f7e5db58c6e8c2b4b738a75d5dcd8e17aad5 Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Thu, 25 Jun 2009 12:31:37 -0700
Subject: 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>
---
 mm/slub.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'mm/slub.c')

diff --git a/mm/slub.c b/mm/slub.c
index 819f056b39c..a9201d83178 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2595,6 +2595,8 @@ static inline int kmem_cache_close(struct kmem_cache *s)
  */
 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) {
-- 
cgit v1.2.3