diff --git a/fs/namespace.c b/fs/namespace.c
index 93c043245c463eb77c4c48316e8ba8ae80f47830..abcdc5f448651fe058b3dfc4bef53135a043a483 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3028,7 +3028,7 @@ void *copy_mount_options(const void __user * data)
 	 * the remainder of the page.
 	 */
 	/* copy_from_user cannot cross TASK_SIZE ! */
-	size = TASK_SIZE - (unsigned long)data;
+	size = TASK_SIZE - (unsigned long)untagged_addr(data);
 	if (size > PAGE_SIZE)
 		size = PAGE_SIZE;