[PATCH] mm: vmscan: reclaim highmem zone if buffer_heads is over limit

[Minchan Kim]

We have been reclaimed highmem zone if buffer_heads is over limit
but [1] changed the behavior so it doesn't reclaim highmem zone
although buffer_heads is over the limit.
This patch restores the logic.

As well, [2] removed classzone_idx so we don't need code related to
it. This patch cleans it up.

[1] commit 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from shrink_zone()")
[2] commit 5acbd3bfc93b ("mm, oom: rework oom detection")

Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 mm/vmscan.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c7696a2e11c7..6e67de2a61ed 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2550,17 +2550,9 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
 		sc->gfp_mask |= __GFP_HIGHMEM;
 
 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
-					requested_highidx, sc->nodemask) {
-		enum zone_type classzone_idx;
-
+					gfp_zone(sc->gfp_mask), sc->nodemask) {
 		if (!populated_zone(zone))
 			continue;
-
-		classzone_idx = requested_highidx;
-		while (!populated_zone(zone->zone_pgdat->node_zones +
-							classzone_idx))
-			classzone_idx--;
-
 		/*
 		 * Take care memory controller reclaiming has small influence
 		 * to global LRU.
-- 
1.9.1