commit 7e5b528b4ce31208ef5c240c14beec4853d8262c
author Dmitry Vyukov <dvyukov@google.com> Fri Dec 12 16:56:30 2014 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> Sat Dec 13 12:42:49 2014 -0800
tree d42f428802ade412a8c3c6ec5271a9e29c68c806
parent 6a2d5679b4a852a3bf80c570644456ab466ab714

mm/vmalloc.c: fix memory ordering bug

Read memory barriers must follow the read operations.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8a18196..39c3388 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2574,10 +2574,10 @@
 		if (!counters)
 			return;
 
-		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
-		smp_rmb();
 		if (v->flags & VM_UNINITIALIZED)
 			return;
+		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+		smp_rmb();
 
 		memset(counters, 0, nr_node_ids * sizeof(unsigned int));