drm causes kernel panic

Built world/kernel with today sources.  Upon starting Xorg 
as a normal user, I was greeted with

Script started on Tue Sep  2 18:12:22 2008
Unread portion of the kernel message buffer:
panic: lock (sleep mutex) drmdev not locked _at_ /usr/src/sys/dev/drm/drm_pci.c:77
cpuid = 0
Uptime: 24s
Physical memory: 8118 MB
Dumping 346 MB: 331 315 299 283 267 251 235 219 203 187 171 155 139 123 107 91 75 59 43 27 11

#0  doadump () at pcpu.h:195
195	pcpu.h: No such file or directory.
	in pcpu.h
(kgdb) bt
#0  doadump () at pcpu.h:195
#1  0xffffffff802ee4da in boot (howto=260)
    at /usr/src/sys/kern/kern_shutdown.c:418
#2  0xffffffff802ee947 in panic (fmt=Variable "fmt" is not available.
)
    at /usr/src/sys/kern/kern_shutdown.c:572
#3  0xffffffff803301ca in witness_unlock (lock=0xffffffff806f3d60, flags=8, 
    file=0xffffffff8055dc88 "/usr/src/sys/dev/drm/drm_pci.c", line=77)
    at /usr/src/sys/kern/subr_witness.c:1460
#4  0xffffffff802e20c6 in _mtx_unlock_flags (m=0xffffff00017b41a8, opts=0, 
    file=0xffffffff8055dc88 "/usr/src/sys/dev/drm/drm_pci.c", line=77)
    at /usr/src/sys/kern/kern_mutex.c:199
#5  0xffffffff8021a945 in drm_pci_alloc (dev=Variable "dev" is not available.
)
    at /usr/src/sys/dev/drm/drm_pci.c:77
#6  0xffffffff80214654 in drm_addmap (dev=0xffffff00017b4000, offset=0, 
    size=16384, type=_DRM_CONSISTENT, flags=Variable "flags" is not available.
)
    at /usr/src/sys/dev/drm/drm_bufs.c:247
#7  0xffffffff80214b8b in drm_addmap_ioctl (dev=0xffffff00017b4000, 
    data=0xffffff000576c480, file_priv=Variable "file_priv" is not available.
)
    at /usr/src/sys/dev/drm/drm_bufs.c:291
#8  0xffffffff8021786e in drm_ioctl (kdev=Variable "kdev" is not available.
)
    at /usr/src/sys/dev/drm/drm_drv.c:952
#9  0xffffffff802bb4e5 in giant_ioctl (dev=0xffffff000188e400, 
    cmd=3223872533, data=0xffffff000576c480 "", fflag=67, 
    td=0xffffff0005a25a20) at /usr/src/sys/kern/kern_conf.c:407
---Type <return> to continue, or q <return> to quit---
#10 0xffffffff80288eea in devfs_ioctl_f (fp=0xffffff0005665c30, 
    com=3223872533, data=0xffffff000576c480, cred=Variable "cred" is not available.
)
    at /usr/src/sys/fs/devfs/devfs_vnops.c:585
#11 0xffffffff80332942 in kern_ioctl (td=0xffffff0005a25a20, fd=Variable "fd" is not available.
)
    at file.h:262
#12 0xffffffff80332ba0 in ioctl (td=0xffffff0005a25a20, 
    uap=0xffffffff2231fbf0) at /usr/src/sys/kern/sys_generic.c:677
#13 0xffffffff804f4f9f in syscall (frame=0xffffffff2231fc80)
    at /usr/src/sys/amd64/amd64/trap.c:897
#14 0xffffffff804d8b6b in Xfast_syscall ()
    at /usr/src/sys/amd64/amd64/exception.S:338
#15 0x000000020185340c in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb) quit
exit

Script done on Tue Sep  2 18:13:12 2008
-- 
Steve