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>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8ed1b775bdc9cafe9aaf2ab74e4acf842ffe1a9d..97b0ed16749ff39cfddf76f8b3aa941761de8b48 100644 (file)
--- 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