diff --git a/mm/swap_state.c b/mm/swap_state.c
index 797c383..7a3ece0 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -75,6 +75,7 @@
 	BUG_ON(!PageLocked(page));
 	BUG_ON(PageSwapCache(page));
 	BUG_ON(PagePrivate(page));
+	BUG_ON(!PageSwapBacked(page));
 	error = radix_tree_preload(gfp_mask);
 	if (!error) {
 		page_cache_get(page);
@@ -303,6 +304,7 @@
 		 * May fail (-ENOMEM) if radix-tree node allocation failed.
 		 */
 		set_page_locked(new_page);
+		SetPageSwapBacked(new_page);
 		err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL);
 		if (likely(!err)) {
 			/*
@@ -312,6 +314,7 @@
 			swap_readpage(NULL, new_page);
 			return new_page;
 		}
+		ClearPageSwapBacked(new_page);
 		clear_page_locked(new_page);
 		swap_free(entry);
 	} while (err != -ENOMEM);