code: func (m *cgroupManagerImpl) Exists(name CgroupName) bool {
  	// Get map of all cgroup paths on the system for the particular cgroup
  	cgroupPaths := m.buildCgroupPaths(name)
  
  	// the presence of alternative control groups not known to runc confuses
  	// the kubelet existence checks.
  	// ideally, we would have a mechanism in runc to support Exists() logic
  	// scoped to the set control groups it understands.  this is being discussed
  	// in https://github.com/opencontainers/runc/issues/1440
  	// once resolved, we can remove this code.
  	whitelistControllers := sets.NewString("cpu", "cpuacct", "cpuset", "memory", "systemd")
  	if utilfeature.DefaultFeatureGate.Enabled(kubefeatures.SupportPodPidsLimit) || utilfeature.DefaultFeatureGate.Enabled(kubefeatures.SupportNodePidsLimit) {
  		whitelistControllers.Insert("pids")
  	}
  	var missingPaths []string
  	// If even one cgroup path doesn't exist, then the cgroup doesn't exist.
  	for controller, path := range cgroupPaths {
  		// ignore mounts we don't care about
  		if !whitelistControllers.Has(controller) {
  			continue
  		}
  		if !libcontainercgroups.PathExists(path) {
  			missingPaths = append(missingPaths, path)
  		}
  	}
  
  	if len(missingPaths) > 0 {
  		klog.V(4).Infof("The Cgroup %v has some missing paths: %v", name, missingPaths)
  		return false
  	}
  
  	return true
  }
docs: // Exists checks if all subsystem cgroups already exist