[PATCH] Fix memory ordering bug in mm/vmalloc.c.

[PATCH] Fix memory ordering bug in mm/vmalloc.c.

[Dmitry Vyukov]

Read memory barriers must follow the read operations.

Cc: edumazet@google.com
Cc: js1304@gmail.com
Cc: iamjoonsoo.kim@lge.com
Cc: akpm@linux-foundation.org
Cc: linux-mm@kvack.org

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
---
 mm/vmalloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 90520af..e052a34 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2575,10 +2575,10 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)
 		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));
 
-- 
2.2.0.rc0.207.ga3a616c

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Re: [PATCH] Fix memory ordering bug in mm/vmalloc.c.

[Joonsoo Kim]

On Mon, Dec 01, 2014 at 11:11:26AM +0300, Dmitry Vyukov wrote:
> Read memory barriers must follow the read operations.

Hello, Dmitry.

You are right.
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Thanks.

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