---

yaml
---
r: 272125
b: refs/heads/master
c: a18bba0
h: refs/heads/master
i:
  272123: 0c27f3f
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ee72886d8ed5d9de3fa0ed3b99a7ca7702576a96
+refs/heads/master: a18bba061c789f5815c3efc3c80e6ac269911964

trunk/mm/vmscan.c

@@ -495,15 +495,6 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
 			return PAGE_ACTIVATE;
 		}
 
-		/*
-		 * Wait on writeback if requested to. This happens when
-		 * direct reclaiming a large contiguous area and the
-		 * first attempt to free a range of pages fails.
-		 */
-		if (PageWriteback(page) &&
-		    (sc->reclaim_mode & RECLAIM_MODE_SYNC))
-			wait_on_page_writeback(page);
-
 		if (!PageWriteback(page)) {
 			/* synchronous write or broken a_ops? */
 			ClearPageReclaim(page);
@@ -804,12 +795,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 
 		if (PageWriteback(page)) {
 			/*
-			 * Synchronous reclaim is performed in two passes,
-			 * first an asynchronous pass over the list to
-			 * start parallel writeback, and a second synchronous
-			 * pass to wait for the IO to complete.  Wait here
-			 * for any page for which writeback has already
-			 * started.
+			 * Synchronous reclaim cannot queue pages for
+			 * writeback due to the possibility of stack overflow
+			 * but if it encounters a page under writeback, wait
+			 * for the IO to complete.
 			 */
 			if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) &&
 			    may_enter_fs)
@@ -1414,7 +1403,7 @@ static noinline_for_stack void update_isolated_counts(struct zone *zone,
 }
 
 /*
- * Returns true if the caller should wait to clean dirty/writeback pages.
+ * Returns true if a direct reclaim should wait on pages under writeback.
  *
  * If we are direct reclaiming for contiguous pages and we do not reclaim
  * everything in the list, try again and wait for writeback IO to complete.