vmscan: don't attempt to reclaim anon page in lumpy reclaim when no swap space is...

The VM already avoids attempting to reclaim anon pages in various places,
But it doesn't avoid it for lumpy reclaim.

It shuffles lru list unnecessary so that it is pointless.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 208071c48bf2fbedba600039a6d19a91c5ce3659..ece2ecb081025dd5f1ebf74ed24c0ce70bd5a4bf 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -935,6 +935,16 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
                        /* Check that we have not crossed a zone boundary. */
                        if (unlikely(page_zone_id(cursor_page) != zone_id))
                                continue;
+
+                       /*
+                        * If we don't have enough swap space, reclaiming of
+                        * anon page which don't already have a swap slot is
+                        * pointless.
+                        */
+                       if (nr_swap_pages <= 0 && PageAnon(cursor_page) &&
+                                       !PageSwapCache(cursor_page))
+                               continue;
+
                        if (__isolate_lru_page(cursor_page, mode, file) == 0) {
                                list_move(&cursor_page->lru, dst);
                                mem_cgroup_del_lru(cursor_page);