log.Warnf("failed to read proc %v stats: %v", p.PID, err)
			if best == "" {
				best = ns
			}
			continue
		}
		// Get the oldest one.
		if s.Starttime < oldest {
			oldest = s.Starttime
			best = ns
		}
	}
	if best == "" {
		return "", fmt.Errorf("failed to find network namespace")
	}
	return best, nil