return fmt.Errorf(msg, path, crossMounts)
	}
	return nil
}

// readProcMounts reads the given mountFilePath (normally /proc/mounts) and produces a hash
// of the contents.  If the out argument is not nil, this fills it with MountPoint structs.
func readProcMounts(mountFilePath string) (mountInfos, error) {
	file, err := os.Open(mountFilePath)
	if err != nil {
		return nil, err
	}