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 8a18196..39c3388 100644 (file)
--- 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));