USB Memory sticks: Failure mode for forgotten umount?

[Hannah Schroeter <hannah_(_at_)_schlund_(_dot_)_de>]

Hello!

Just experimented. If you put in a memory stick, mount
(mount /dev/sd0i /mnt), and it works. Now I pull it out, "forgetting"
to umount it.

It seems I can't umount it ever again, umount hangs (wchan vn_loc)
forever.

And plugging it in again doesn't attach any kind of device any more.

How difficult would it be to have a better failure mode for that?

Yes I know sane persons don't do that, but it's easy to forget things
sometimes...

Kind regards,

Hannah.