mm: forbid lumpy-reclaim in shrink_active_list()

Reset the reclaim mode in shrink_active_list() to RECLAIM_MODE_SINGLE |
RECLAIM_MODE_ASYNC.  (sync/async sign is used only in shrink_page_list
and does not affect shrink_active_list)

Currenly shrink_active_list() sometimes works in lumpy-reclaim mode, if
RECLAIM_MODE_LUMPYRECLAIM is left over from an earlier
shrink_inactive_list().  Meanwhile, in age_active_anon()
sc->reclaim_mode is totally zero.  So the current behavior is too
complex and confusing, and this looks like bug.

In general, shrink_active_list() populates the inactive list for the
next shrink_inactive_list().  Lumpy shring_inactive_list() isolates
pages around the chosen one from both the active and inactive lists.
So, there is no reason for lumpy isolation in shrink_active_list().

See also: https://lkml.org/lkml/2012/3/15/583

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Proposed-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
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 55d86c9506f35b99a7f1362efe48d9f19cfc7be4..49f15ef0a99a3f7f78adcd687f3ed54c421b2a0b 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1690,6 +1690,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
 
        lru_add_drain();
 
+       reset_reclaim_mode(sc);
+
        if (!sc->may_unmap)
                isolate_mode |= ISOLATE_UNMAPPED;
        if (!sc->may_writepage)