2 files changed, 11 insertions, 29 deletions

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 2622115276aa..1829c65f8371 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -535,17 +535,15 @@ Note:
 
 5.3 swappiness
 
-Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
+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.
 
-Following cgroups' swappiness can't be changed.
-- root cgroup (uses /proc/sys/vm/swappiness).
-- a cgroup which uses hierarchy and it has other cgroup(s) below it.
-- a cgroup which uses hierarchy and not the root of hierarchy.
-
 5.4 failcnt
 
 A memory cgroup provides memory.failcnt and memory.memsw.failcnt files.
@@ -754,7 +752,6 @@ You can disable the OOM-killer by writing "1" to memory.oom_control file, as:
 
         #echo 1 > memory.oom_control
 
-This operation is only allowed to the top cgroup of a sub-hierarchy.
 If OOM-killer is disabled, tasks under cgroup will hang/sleep
 in memory cgroup's OOM-waitqueue when they request accountable memory.
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7bab1de50f48..20f47d9cd8b2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5444,22 +5444,14 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
                                        struct cftype *cft, u64 val)
 {
         struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-        struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
 
-        if (val > 100 || !parent)
+        if (val > 100)
                 return -EINVAL;
 
-        mutex_lock(&memcg_create_mutex);
-
-        /* If under hierarchy, only empty-root can set this value */
-        if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
-                mutex_unlock(&memcg_create_mutex);
-                return -EINVAL;
-        }
-
-        memcg->swappiness = val;
-
-        mutex_unlock(&memcg_create_mutex);
+        if (css_parent(css))
+                memcg->swappiness = val;
+        else
+                vm_swappiness = val;
 
         return 0;
 }
@@ -5791,22 +5783,15 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
         struct cftype *cft, u64 val)
 {
         struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-        struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
 
         /* cannot set to root cgroup and only 0 and 1 are allowed */
-        if (!parent || !((val == 0) || (val == 1)))
+        if (!css_parent(css) || !((val == 0) || (val == 1)))
                 return -EINVAL;
 
-        mutex_lock(&memcg_create_mutex);
-        /* oom-kill-disable is a flag for subhierarchy. */
-        if ((parent->use_hierarchy) || memcg_has_children(memcg)) {
-                mutex_unlock(&memcg_create_mutex);
-                return -EINVAL;
-        }
         memcg->oom_kill_disable = val;
         if (!val)
                 memcg_oom_recover(memcg);
-        mutex_unlock(&memcg_create_mutex);
+
         return 0;
 }