mm: vmscan: immediately reclaim end-of-LRU dirty pages when writeback completes

When direct reclaim encounters a dirty page, it gets recycled around the
LRU for another cycle.  This patch marks the page PageReclaim similar to
deactivate_page() so that the page gets reclaimed almost immediately after
the page gets cleaned.  This is to avoid reclaiming clean pages that are
younger than a dirty page encountered at the end of the LRU that might
have been something like a use-once page.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 1 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7b0573f33a27..a297603d35bc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -866,7 +866,15 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                          */
                         if (page_is_file_cache(page) &&
                                         (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
-                                inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP);
+                                /*
+                                 * Immediately reclaim when written back.
+                                 * Similar in principal to deactivate_page()
+                                 * except we already have the page isolated
+                                 * and know it's dirty
+                                 */
+                                inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE);
+                                SetPageReclaim(page);
+
                                 goto keep_locked;
                         }