From: Dmitry Vyukov <dvyukov@google.com>
Date: Sat, 13 Dec 2014 00:56:30 +0000 (-0800)
Subject: mm/vmalloc.c: fix memory ordering bug
X-Git-Tag: firefly_0821_release~176^2~2692^2~50
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7e5b528b4ce31208ef5c240c14beec4853d8262c;p=firefly-linux-kernel-4.4.55.git

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>
---

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8a18196fcdff..39c338896416 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2574,10 +2574,10 @@ 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));