how to recover from "stalled" USB disk?

[Karel J. Bosschaart]

Hi,

Is there a way to recover, without reboot, from a USB flash drive showing

umass0: BBB bulk-in clear stall failed, TIMEOUT
umass0: BBB bulk-out clear stall failed, TIMEOUT
umass0: BBB reset failed, TIMEOUT

? I guess I need to unplug/replug it but I have a process (mdir, from
the mtools collection) attempting to read it. It can't be killed, my
understanding is that it ignores all signals (from top I noticed it
in state cbwait, later g_wait).

A 'camcontrol reset 1' gives: Reset of bus 1 returned error 0x3a

I'm waiting now to see if there is (hopefully) a timeout on the mdir
command but if there is it is taking a very long time :-(. 

Any suggestions welcome,
Karel.