1 files changed, 3 insertions, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index e9ef599498b5..d68421dd64ef 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -372,7 +372,9 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                         /* make sure dst_mm is on swapoff's mmlist. */
                         if (unlikely(list_empty(&dst_mm->mmlist))) {
                                 spin_lock(&mmlist_lock);
-                                list_add(&dst_mm->mmlist, &src_mm->mmlist);
+                                if (list_empty(&dst_mm->mmlist))
+                                        list_add(&dst_mm->mmlist,
+                                                 &src_mm->mmlist);
                                 spin_unlock(&mmlist_lock);
                         }
                 }