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-rw-r--r--Documentation/cgroups/memory.txt11
-rw-r--r--mm/memcontrol.c29
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;
}