def METHOD_NAME(self, device=None, label=None):
    p = ProcMountsParser()
    if label is not None:
        b = BlkidParser(log=self.log)
        for e in b.parts:
            if label == e.label:
                device = e.device
                break
    for m in p.mounts:
        if device is not None and device in m.device:
            try:
                self.check_call(('umount', m.device,),
                                vmode=self.V1)
            except CalledProcessError, what:
                self.log.warn("cannot umount %s: %s",
                              m.device, str(what))
    return 0