memcg: disable hierarchy support if bound to the legacy cgroup hierarchy
memcg: disable hierarchy support if bound to the legacy cgroup hierarchy

If the memory cgroup controller is initially mounted in the scope of the
default cgroup hierarchy and then remounted to a legacy hierarchy, it will
still have hierarchy support enabled, which is incorrect.  We should
disable hierarchy support if bound to the legacy cgroup hierarchy.

Signed-off-by: Vladimir Davydov <0d62248ee021b6e01c0ee596a62a5b145b996974@parallels.com>
Signed-off-by: Johannes Weiner <331be22c6b63ca3e0a03d408c2d906b1b02cd5f2@cmpxchg.org>
Acked-by: Michal Hocko <829500b200af6c2a0eca4dfd5c388e6b8fbe8dc6@suse.cz>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs