cpuset: initialize top_cpuset's configured masks at mount
We now have to support different behaviors for default hierachy and
legacy hiearchy, top_cpuset's configured masks need to be initialized
accordingly.
Suppose we've offlined cpu1.
On default hierarchy:
# mount -t cgroup -o __DEVEL__sane_behavior xxx /cpuset
# cat /cpuset/cpuset.cpus
0-15
On legacy hierarchy:
# mount -t cgroup xxx /cpuset
# cat /cpuset/cpuset.cpus
0,2-15
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>