---

yaml
---
r: 335795
b: refs/heads/master
c: 215c02b
h: refs/heads/master
i:
  335793: a142deb
  335791: 84589b2
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 498c2280212327858e521e9d21345d4cc2637f54
+refs/heads/master: 215c02bc33bbd5ff4d7379a909462d11f0103218

trunk/mm/shmem.c

@@ -1145,8 +1145,20 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 		if (!error) {
 			error = shmem_add_to_page_cache(page, mapping, index,
 						gfp, swp_to_radix_entry(swap));
-			/* We already confirmed swap, and make no allocation */
-			VM_BUG_ON(error);
+			/*
+			 * We already confirmed swap under page lock, and make
+			 * no memory allocation here, so usually no possibility
+			 * of error; but free_swap_and_cache() only trylocks a
+			 * page, so it is just possible that the entry has been
+			 * truncated or holepunched since swap was confirmed.
+			 * shmem_undo_range() will have done some of the
+			 * unaccounting, now delete_from_swap_cache() will do
+			 * the rest (including mem_cgroup_uncharge_swapcache).
+			 * Reset swap.val? No, leave it so "failed" goes back to
+			 * "repeat": reading a hole and writing should succeed.
+			 */
+			if (error)
+				delete_from_swap_cache(page);
 		}
 		if (error)
 			goto failed;