umount hanging and killing uninterruptable process

I tried to unmount floppy with "umount /mnt" and umount hung.  And fd0a
was unusable: "Device busy".

A day later the umount is in "DW+" state.

(I wonder if this is related to shlight/nfs hanging problem from day
before.)

top says it is "synclk". (Where can I find out more about these states?)

A ktrace on the PID simply says:
  5998 umount   EMUL  "netbsd"

Any suggestions on how I can research this further?

How can I kill a process in some uninterruptable state?

Is there a kernel timeout that will kill it sometime (after a SIGKILL)?

And if so, where can I learn about this?

(This is NetBSD/i386 1.6.)

Thanks,

   Jeremy C. Reed

http://www.bsdnewsletter.com/