snd_uaudio: Fatal trap 12: page fault while in kernel mode

I reproducible get the following panic less than a second after
inserting a Turtle Beach AudioAdvantage stick with the snd_uaudio
module loaded:

fk_at_r500 /usr/crash $kgdb /boot/kernel/kernel.symbols vmcore.0 
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Unread portion of the kernel message buffer:

cpuid = 0; apic id = 00
fault virtual address   = 0x20
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff803f31c1
stack pointer           = 0x28:0xffffff803a393440
frame pointer           = 0x28:0xffffff803a393460
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = resume, IOPL = 0
current process         = 36 (usbus4)
panic: from debugger
cpuid = 0
Uptime: 2m12s
Dumping 1992 MB (5 chunks)
  chunk 0: 1MB (155 pages) ... ok
  chunk 1: 1990MB (509345 pages) 1974 1958 1942 1926 1910 1894 [...]... ok
  chunk 2: 2MB (273 pages) ... ok
  chunk 3: 1MB (184 pages)

Reading symbols from /boot/kernel/zfs.ko...Reading symbols from /boot/kernel/zfs.ko.symbols...done.
done.
[...]
done.
Loaded symbols for /boot/kernel/snd_uaudio.ko
#0  doadump () at pcpu.h:223
223     pcpu.h: No such file or directory.
        in pcpu.h
(kgdb) where
#0  doadump () at pcpu.h:223
#1  0xffffffff803bb25d in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:419
#2  0xffffffff803bb64c in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:575
#3  0xffffffff801eddf7 in db_panic (addr=Variable "addr" is not available.
) at /usr/src/sys/ddb/db_command.c:478
#4  0xffffffff801ee201 in db_command (last_cmdp=0xffffffff8081d240, cmd_table=Variable "cmd_table" is not available.
) at /usr/src/sys/ddb/db_command.c:445
#5  0xffffffff801ee450 in db_command_loop () at /usr/src/sys/ddb/db_command.c:498
#6  0xffffffff801f03a9 in db_trap (type=Variable "type" is not available.
) at /usr/src/sys/ddb/db_main.c:229
#7  0xffffffff803e6935 in kdb_trap (type=12, code=0, tf=0xffffff803a393390) at /usr/src/sys/kern/subr_kdb.c:534
#8  0xffffffff805ac48d in trap_fatal (frame=0xffffff803a393390, eva=Variable "eva" is not available.
) at /usr/src/sys/amd64/amd64/trap.c:847
#9  0xffffffff805ad04e in trap (frame=0xffffff803a393390) at /usr/src/sys/amd64/amd64/trap.c:345
#10 0xffffffff805943f3 in calltrap () at /usr/src/sys/amd64/amd64/exception.S:224
#11 0xffffffff803f31c1 in turnstile_broadcast (ts=0x0, queue=0) at /usr/src/sys/kern/subr_turnstile.c:831
#12 0xffffffff803aee70 in _mtx_unlock_sleep (m=0xffffffff81e37120, opts=Variable "opts" is not available.
) at /usr/src/sys/kern/kern_mutex.c:677
#13 0xffffffff80331d4f in usbd_do_request_flags (udev=0xffffff003fcfe000, mtx=0xffffffff81e37120, req=0xffffff803a393550, data=0xffffff803a393560, flags=0, actlen=0x0, 
    timeout=5000) at /usr/src/sys/dev/usb/usb_request.c:312
#14 0xffffffff824272e2 in uaudio_mixer_get (udev=Variable "udev" is not available.
) at /usr/src/sys/modules/sound/driver/uaudio/../../../../dev/sound/usb/uaudio.c:2961
#15 0xffffffff8242741a in uaudio_mixer_add_ctl (sc=0xffffff003f3c3000, mc=0xffffff803a3938a0) at /usr/src/sys/modules/sound/driver/uaudio/../../../../dev/sound/usb/uaudio.c:1604
#16 0xffffffff82429165 in uaudio_attach (dev=0xffffff003f723400) at /usr/src/sys/modules/sound/driver/uaudio/../../../../dev/sound/usb/uaudio.c:1944
#17 0xffffffff803e1569 in device_attach (dev=0xffffff003f723400) at device_if.h:178
#18 0xffffffff80326941 in usb_probe_and_attach_sub (udev=0xffffff003fcfe000, uaa=0xffffff803a393ae0) at /usr/src/sys/dev/usb/usb_device.c:1146
#19 0xffffffff80326dfd in usb_probe_and_attach (udev=0xffffff003fcfe000, iface_index=Variable "iface_index" is not available.
) at /usr/src/sys/dev/usb/usb_device.c:1305
#20 0xffffffff8032f7ca in uhub_explore (udev=0xffffff000380a000) at /usr/src/sys/dev/usb/usb_hub.c:238
#21 0xffffffff8031be61 in usb_bus_explore (pm=Variable "pm" is not available.
) at /usr/src/sys/dev/usb/controller/usb_controller.c:235
#22 0xffffffff803319f0 in usb_process (arg=Variable "arg" is not available.
) at /usr/src/sys/dev/usb/usb_process.c:161
#23 0xffffffff80398182 in fork_exit (callout=0xffffffff80331930 <usb_process>, arg=0xffffff80002dee88, frame=0xffffff803a393c80) at /usr/src/sys/kern/kern_fork.c:838
#24 0xffffffff805948ce in fork_trampoline () at /usr/src/sys/amd64/amd64/exception.S:561
#25 0x0000000000000000 in ?? ()
#26 0x0000000000000000 in ?? ()
#27 0x0000000000000001 in ?? ()
#28 0x0000000000000000 in ?? ()

This is on:
FreeBSD 8.0-BETA2 #3: Fri Aug 14 15:19:08 CEST 2009 fk_at_r500.local:/usr/obj/usr/src/sys/ZOEY  amd64
but also happens with a slightly older kernel on i386.

Fabian