diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2e8c2b0..0d986c1 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -911,15 +911,24 @@
 		for (i = 0; i < nr_pages; i++) {
 			struct page *page = pvec.pages[i];
 
+			/*
+			 * At this point, the page may be truncated or
+			 * invalidated (changing page->mapping to NULL), or
+			 * even swizzled back from swapper_space to tmpfs file
+			 * mapping. However, page->index will not change
+			 * because we have a reference on the page.
+			 */
+			if (page->index > end) {
+				/*
+				 * can't be range_cyclic (1st pass) because
+				 * end == -1 in that case.
+				 */
+				done = 1;
+				break;
+			}
+
 			done_index = page->index + 1;
 
-			/*
-			 * At this point we hold neither mapping->tree_lock nor
-			 * lock on the page itself: the page may be truncated or
-			 * invalidated (changing page->mapping to NULL), or even
-			 * swizzled back from swapper_space to tmpfs file
-			 * mapping
-			 */
 			lock_page(page);
 
 			/*
@@ -936,15 +945,6 @@
 				continue;
 			}
 
-			if (page->index > end) {
-				/*
-				 * can't be range_cyclic (1st pass) because
-				 * end == -1 in that case.
-				 */
-				done = 1;
-				goto continue_unlock;
-			}
-
 			if (!PageDirty(page)) {
 				/* someone wrote it for us */
 				goto continue_unlock;