mount hang attempting to mount a umass device

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

My mount and shell (ksh in an xterm) hang when doing a mount of a 
USB-based flash disk device. For example:

umass0 at uhub4 port 5 configuration 1 interface 0
umass0: vendor 0x10d6 USB 2.0(HS) Flash Disk, rev 2.00/1.00, addr 2
umass0: using ATAPI over Bulk-Only
atapibus1 at umass0: 2 targets
cd1 at atapibus1 drive 0: <GPX, , 1.00> cdrom removable

This is a GPX Digital Audio Player ML648B.

new-host$ sudo mount /dev/cd1d /mnt
Password:
mount: cannot open `/dev/cd1d': Operation not supported by device
new-host$ sudo mount /dev/cd1a /mnt 

^C
^Z

mount is running, but no file system is mounted.

root  3764  0.0  0.1   1080    568 ttyp7  D+   Sat09AM   0:00.00 mount 
/dev/cd1a /mnt 
reed 20589  0.0  0.1   2824   1092 ttyp7  Is   Thu03PM   0:00.02 ksh 
reed  1759  0.0  0.3   5508   3508 ?      S    Thu03PM   0:05.96 
/usr/X11R6/bin/xterm

As you can see the mount has been hanging for a couple days. Even after 
unplugging the USB device, and multiple SIGKILL attempts, no change.

My kernel is:

NetBSD new-host 5.0.0_PATCH NetBSD 5.0.0_PATCH (GENERIC) #0: Wed Jul 15 
12:42:22 UTC 2009  
builds%b8.netbsd.org@localhost:/home/builds/ab/netbsd-5-0/i386/200907150000Z-obj/home/builds/ab/netbsd-5-0/src/sys/arch/i386/compile/GENERIC
 
i386

This happens with a different physical device too.

Any ideas on how to kill this?