code: func notifyOnOOM(paths map[string]string) (<-chan struct{}, error) {
  	dir := paths[oomCgroupName]
  	if dir == "" {
  		return nil, fmt.Errorf("There is no path for %q in state", oomCgroupName)
  	}
  	oomControl, err := os.Open(filepath.Join(dir, "memory.oom_control"))
  	if err != nil {
  		return nil, err
  	}
  	fd, _, syserr := syscall.RawSyscall(syscall.SYS_EVENTFD2, 0, syscall.FD_CLOEXEC, 0)
  	if syserr != 0 {
  		oomControl.Close()
  		return nil, syserr
  	}
  
  	eventfd := os.NewFile(fd, "eventfd")
  
  	eventControlPath := filepath.Join(dir, "cgroup.event_control")
  	data := fmt.Sprintf("%d %d", eventfd.Fd(), oomControl.Fd())
  	if err := ioutil.WriteFile(eventControlPath, []byte(data), 0700); err != nil {
  		eventfd.Close()
  		oomControl.Close()
  		return nil, err
  	}
  	ch := make(chan struct{})
  	go func() {
  		defer func() {
  			close(ch)
  			eventfd.Close()
  			oomControl.Close()
  		}()
  		buf := make([]byte, 8)
  		for {
  			if _, err := eventfd.Read(buf); err != nil {
  				return
  			}
  			// When a cgroup is destroyed, an event is sent to eventfd.
  			// So if the control path is gone, return instead of notifying.
  			if _, err := os.Lstat(eventControlPath); os.IsNotExist(err) {
  				return
  			}
  			ch <- struct{}{}
  		}
  	}()
  	return ch, nil
  }
docs: // notifyOnOOM returns channel on which you can expect event about OOM,
  // if process died without OOM this channel will be closed.
  // s is current *libcontainer.State for container.