revert "memcg, vmscan: do not fall into reclaim-all pass too quickly"

Revert commit e975de998b96 ("memcg, vmscan: do not fall into reclaim-all
pass too quickly")

I merged this prematurely - Michal and Johannes still disagree about the
overall design direction and the future remains unclear.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 17 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8ed1b775bdc9..97b0ed16749f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2176,11 +2176,10 @@ static inline bool should_continue_reclaim(struct zone *zone,
         }
 }
 
-static int
+static void
 __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
 {
         unsigned long nr_reclaimed, nr_scanned;
-        int groups_scanned = 0;
 
         do {
                 struct mem_cgroup *root = sc->target_mem_cgroup;
@@ -2198,7 +2197,6 @@ __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
                 while ((memcg = mem_cgroup_iter_cond(root, memcg, &reclaim, filter))) {
                         struct lruvec *lruvec;
 
-                        groups_scanned++;
                         lruvec = mem_cgroup_zone_lruvec(zone, memcg);
 
                         shrink_lruvec(lruvec, sc);
@@ -2226,8 +2224,6 @@ __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
 
         } while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed,
                                          sc->nr_scanned - nr_scanned, sc));
-
-        return groups_scanned;
 }
 
 
@@ -2235,19 +2231,8 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc)
 {
         bool do_soft_reclaim = mem_cgroup_should_soft_reclaim(sc);
         unsigned long nr_scanned = sc->nr_scanned;
-        int scanned_groups;
 
-        scanned_groups = __shrink_zone(zone, sc, do_soft_reclaim);
-        /*
-         * memcg iterator might race with other reclaimer or start from
-         * a incomplete tree walk so the tree walk in __shrink_zone
-         * might have missed groups that are above the soft limit. Try
-         * another loop to catch up with others. Do it just once to
-         * prevent from reclaim latencies when other reclaimers always
-         * preempt this one.
-         */
-        if (do_soft_reclaim && !scanned_groups)
-                __shrink_zone(zone, sc, do_soft_reclaim);
+        __shrink_zone(zone, sc, do_soft_reclaim);
 
         /*
          * No group is over the soft limit or those that are do not have