Add a new kernel API to attach a task to current task's cgroup
in all the active hierarchies.
Signed-off-by: NSridhar Samudrala <sri@us.ibm.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NPaul Menage <menage@google.com>
Acked-by: NLi Zefan <lizf@cn.fujitsu.com>