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.

[[email protected]: cleanup]
Signed-off-by: Minchan Kim <[email protected]>
Reviewed-by: KOSAKI Motohiro <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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);