3 files changed, 16 insertions, 19 deletions

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 4937e6fff9b4..b3429aec444c 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -540,14 +540,13 @@ Note:
 
 5.3 swappiness
 
-Similar to /proc/sys/vm/swappiness, but only affecting reclaim that is
-triggered by this cgroup's hard limit.  The tunable in the root cgroup
-corresponds to the global swappiness setting.
-
-Please note that unlike the global swappiness, memcg knob set to 0
-really prevents from any swapping even if there is a swap storage
-available. This might lead to memcg OOM killer if there are no file
-pages to reclaim.
+Overrides /proc/sys/vm/swappiness for the particular group. The tunable
+in the root cgroup corresponds to the global swappiness setting.
+
+Please note that unlike during the global reclaim, limit reclaim
+enforces that 0 swappiness really prevents from any swapping even if
+there is a swap storage available. This might lead to memcg OOM killer
+if there are no file pages to reclaim.
 
 5.4 failcnt
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a500cb0594c4..9bf8a84bcaae 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1550,7 +1550,7 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
 int mem_cgroup_swappiness(struct mem_cgroup *memcg)
 {
         /* root ? */
-        if (!css_parent(&memcg->css))
+        if (mem_cgroup_disabled() || !css_parent(&memcg->css))
                 return vm_swappiness;
 
         return memcg->swappiness;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 05d41c0d7f6c..f44476a41544 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -83,6 +83,9 @@ struct scan_control {
         /* Scan (total_size >> priority) pages at once */
         int priority;
 
+        /* anon vs. file LRUs scanning "ratio" */
+        int swappiness;
+
         /*
          * The memory cgroup that hit its limit and as a result is the
          * primary target of this reclaim invocation.
@@ -1845,13 +1848,6 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
         return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
 }
 
-static int vmscan_swappiness(struct scan_control *sc)
-{
-        if (global_reclaim(sc))
-                return vm_swappiness;
-        return mem_cgroup_swappiness(sc->target_mem_cgroup);
-}
-
 enum scan_balance {
         SCAN_EQUAL,
         SCAN_FRACT,
@@ -1912,7 +1908,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
          * using the memory controller's swap limit feature would be
          * too expensive.
          */
-        if (!global_reclaim(sc) && !vmscan_swappiness(sc)) {
+        if (!global_reclaim(sc) && !sc->swappiness) {
                 scan_balance = SCAN_FILE;
                 goto out;
         }
@@ -1922,7 +1918,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
          * system is close to OOM, scan both anon and file equally
          * (unless the swappiness setting disagrees with swapping).
          */
-        if (!sc->priority && vmscan_swappiness(sc)) {
+        if (!sc->priority && sc->swappiness) {
                 scan_balance = SCAN_EQUAL;
                 goto out;
         }
@@ -1965,7 +1961,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
          * With swappiness at 100, anonymous and file have the same priority.
          * This scanning priority is essentially the inverse of IO cost.
          */
-        anon_prio = vmscan_swappiness(sc);
+        anon_prio = sc->swappiness;
         file_prio = 200 - anon_prio;
 
         /*
@@ -2265,6 +2261,7 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc)
 
                         lruvec = mem_cgroup_zone_lruvec(zone, memcg);
 
+                        sc->swappiness = mem_cgroup_swappiness(memcg);
                         shrink_lruvec(lruvec, sc);
 
                         /*
@@ -2731,6 +2728,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
                 .may_swap = !noswap,
                 .order = 0,
                 .priority = 0,
+                .swappiness = mem_cgroup_swappiness(memcg),
                 .target_mem_cgroup = memcg,
         };
         struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);