diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 82e15ba..455093f 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1704,7 +1704,7 @@ static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
 		 * mapping being torn down is communicated in siginfo, see
 		 * kill_proc()
 		 */
-		loff_t start = (index << PAGE_SHIFT) & ~(size - 1);
+		loff_t start = ((loff_t)index << PAGE_SHIFT) & ~(size - 1);
 
 		unmap_mapping_range(mapping, start, size, 0);
 	}