1 files changed, 10 insertions, 0 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index fbcac3bdcf19..777af57fd8c8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -544,6 +544,16 @@ redo:
                  */
                 lru = LRU_UNEVICTABLE;
                 add_page_to_unevictable_list(page);
+                /*
+                 * When racing with an mlock clearing (page is
+                 * unlocked), make sure that if the other thread does
+                 * not observe our setting of PG_lru and fails
+                 * isolation, we see PG_mlocked cleared below and move
+                 * the page back to the evictable list.
+                 *
+                 * The other side is TestClearPageMlocked().
+                 */
+                smp_mb();
         }
 
         /*