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authorTejun Heo <tj@kernel.org>2013-04-15 13:41:15 -0700
committerTejun Heo <tj@kernel.org>2013-04-15 13:46:27 -0700
commitf00baae7ad6c5f1503528efa852f0be8e9513f0e (patch)
tree6d07f953aa06f01b67ed5161073778118b90e6b9 /mm
parent05fb22ec5456a472a5eadcaacb3e51eca1f8c79c (diff)
downloadblackbird-op-linux-f00baae7ad6c5f1503528efa852f0be8e9513f0e.tar.gz
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memcg: force use_hierarchy if sane_behavior
Turn on use_hierarchy by default if sane_behavior is specified and don't create .use_hierarchy file. It is debatable whether to remove .use_hierarchy file or make it ro as the former could make transition easier in certain cases; however, the behavior changes which will be gated by sane_behavior are intensive including changing basic meaning of certain control knobs in a few controllers and I don't really think keeping this piece would make things easier in any noticeable way, so let's remove it. v2: Explain that mem_cgroup_bind() doesn't have to worry about children as suggested by Michal Hocko. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9715c0c491b0..df87bdd4d692 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5814,6 +5814,7 @@ static struct cftype mem_cgroup_files[] = {
},
{
.name = "use_hierarchy",
+ .flags = CFTYPE_INSANE,
.write_u64 = mem_cgroup_hierarchy_write,
.read_u64 = mem_cgroup_hierarchy_read,
},
@@ -6784,6 +6785,21 @@ static void mem_cgroup_move_task(struct cgroup *cont,
}
#endif
+/*
+ * Cgroup retains root cgroups across [un]mount cycles making it necessary
+ * to verify sane_behavior flag on each mount attempt.
+ */
+static void mem_cgroup_bind(struct cgroup *root)
+{
+ /*
+ * use_hierarchy is forced with sane_behavior. cgroup core
+ * guarantees that @root doesn't have any children, so turning it
+ * on for the root memcg is enough.
+ */
+ if (cgroup_sane_behavior(root))
+ mem_cgroup_from_cont(root)->use_hierarchy = true;
+}
+
struct cgroup_subsys mem_cgroup_subsys = {
.name = "memory",
.subsys_id = mem_cgroup_subsys_id,
@@ -6794,6 +6810,7 @@ struct cgroup_subsys mem_cgroup_subsys = {
.can_attach = mem_cgroup_can_attach,
.cancel_attach = mem_cgroup_cancel_attach,
.attach = mem_cgroup_move_task,
+ .bind = mem_cgroup_bind,
.base_cftypes = mem_cgroup_files,
.early_init = 0,
.use_id = 1,
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