---

yaml
---
r: 209676
b: refs/heads/master
c: d5ed3a4
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f2e41e910320197d55b52e28d99a07130f2ae738
+refs/heads/master: d5ed3a4af77b851b6271ad3d9abc4c57fa3ce0f5

trunk/lib/radix-tree.c

@@ -625,6 +625,8 @@ EXPORT_SYMBOL(radix_tree_tag_get);
  *
  * The function returns number of leaves where the tag was set and sets
  * *first_indexp to the first unscanned index.
+ * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
+ * be prepared to handle that.
  */
 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
 		unsigned long *first_indexp, unsigned long last_index,
@@ -675,7 +677,8 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
 next:
 		/* Go to next item at level determined by 'shift' */
 		index = ((index >> shift) + 1) << shift;
-		if (index > last_index)
+		/* Overflow can happen when last_index is ~0UL... */
+		if (index > last_index || !index)
 			break;
 		if (tagged >= nr_to_tag)
 			break;

trunk/mm/page-writeback.c

@@ -836,7 +836,8 @@ void tag_pages_for_writeback(struct address_space *mapping,
 		spin_unlock_irq(&mapping->tree_lock);
 		WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH);
 		cond_resched();
-	} while (tagged >= WRITEBACK_TAG_BATCH);
+		/* We check 'start' to handle wrapping when end == ~0UL */
+	} while (tagged >= WRITEBACK_TAG_BATCH && start);
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);