mm: vmscan: count only dirty pages as congested

shrink_page_list() counts all pages with a mapping, including clean pages, toward nr_congested if they're on a write-congested BDI. shrink_inactive_list() then sets ZONE_CONGESTED if nr_dirty == nr_congested. Fix this apples-to-oranges comparison by only counting pages for nr_congested if they count for nr_dirty. Signed-off-by: Jamie Liu <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Greg Thelen <[email protected]> Cc: Hugh Dickins <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
chewitt · Dec 11, 2014 · 1da58ee · 1da58ee
1 parent ab1f306
commit 1da58ee
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/mm/vmscan.c b/mm/vmscan.c
@@ -874,7 +874,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * end of the LRU a second time.
 		 */
 		mapping = page_mapping(page);
-		if ((mapping && bdi_write_congested(mapping->backing_dev_info)) ||
+		if (((dirty || writeback) && mapping &&
+		     bdi_write_congested(mapping->backing_dev_info)) ||
 		    (writeback && PageReclaim(page)))
 			nr_congested++;