def METHOD_NAME(self):
    """
    Validate the mount hierarchy of cpu and cpuset subsystem.
    Raise an error if cpu and cpuset are mounted on the same hierarchy.
    """
    path = "/proc/1/cgroup"
    if not os.path.exists(path):
        self.die("can't check component mount hierarchy: \
                 file '/proc/1/cgroup' doesn't exist")
    for line in open(path):
        line = line.strip()
        compid, compnames, comppath = line.split(":")
        if not compnames or '=' in compnames:
            continue
        complist = compnames.split(',')
        if "cpu" in complist and "cpuset" in complist:
            self.die("can't mount 'cpu' and 'cpuset' on the same hierarchy")