[PATCH RFC 3/3] mm, vmscan: correct prepare_kswapd_sleep return value

[Jia He]

When there is no reclaimable pages in the zone, even the zone is
not balanced, we let kswapd go sleeping. That is prepare_kswapd_sleep
will return true in this case.

Signed-off-by: Jia He <hejianet@xxxxxxxxx>
---
 mm/vmscan.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7396a0a..54445e2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3140,7 +3140,8 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx)
 		if (!managed_zone(zone))
 			continue;
 
-		if (!zone_balanced(zone, order, classzone_idx))
+		if (!zone_balanced(zone, order, classzone_idx)
+			&& !zone_reclaimable_pages(zone))
 			return false;
 	}
 
-- 
2.5.5