kernel panic during reboot

Hi,

After updating CURRENT yesterday (Sat June 23rd) i am now seeing a
kernel panic during reboot ... i have a crashdump and can provide the
following backtrace ... if additional information is needed i can
probably provide it .. just tell me how to obtain it (not too familiar
with kgdb myself):

Waiting (max 60 seconds) for system process `bufdaemon' to stop...done
Waiting (max 60 seconds) for system process `syncer' to stop...
Syncing disks, vnodes remaining...7 5 3 2 1 0 1 0 0 0 done
All buffers synced.
panic: vput: negative ref cnt
cpuid = 0
KDB: enter: panic
panic: from debugger
cpuid = 0
Uptime: 23m42s
Physical memory: 2027 MB
Dumping 128 MB: 113 97 81 65 49 33 17 1

#0  doadump () at pcpu.h:195
195             __asm __volatile("movl %%fs:0,%0" : "=r" (td));
(kgdb) backtrace
#0  doadump () at pcpu.h:195
#1  0xc075b197 in boot (howto=260)
at /usr/src/sys/kern/kern_shutdown.c:409
#2  0xc075b48e in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:563
#3  0xc0495617 in db_panic (addr=Could not find the frame base for
"db_panic".
) at /usr/src/sys/ddb/db_command.c:433
#4  0xc0495d75 in db_command_loop ()
at /usr/src/sys/ddb/db_command.c:401
#5  0xc04977b5 in db_trap (type=3, code=0)
at /usr/src/sys/ddb/db_main.c:222
#6  0xc0782ac5 in kdb_trap (type=3, code=0, tf=0xe45cfafc)
at /usr/src/sys/kern/subr_kdb.c:502
#7  0xc0a1a4bb in trap (frame=0xe45cfafc)
at /usr/src/sys/i386/i386/trap.c:620
#8  0xc09ffc2b in calltrap () at /usr/src/sys/i386/i386/exception.s:139
#9  0xc0782c42 in kdb_enter (msg=0xc0aa8388 "panic") at cpufunc.h:60
#10 0xc075b474 in panic (fmt=0xc0aae946 "vput: negative ref cnt")
at /usr/src/sys/kern/kern_shutdown.c:547
#11 0xc07d7783 in vput (vp=0xc5b3e990)
at /usr/src/sys/kern/vfs_subr.c:2176
#12 0xc07d0676 in dounmount (mp=0xc5d08d0c, flags=524288, td=0xc5931660)
at /usr/src/sys/kern/vfs_mount.c:1244
#13 0xc07d6653 in vfs_unmountall () at /usr/src/sys/kern/vfs_subr.c:2871
#14 0xc075af11 in boot (howto=0)
at /usr/src/sys/kern/kern_shutdown.c:391
#15 0xc075b347 in reboot (td=0xc5931660, uap=0xe45cfcfc)
at /usr/src/sys/kern/kern_shutdown.c:169
#16 0xc0a19cb5 in syscall (frame=0xe45cfd38)
at /usr/src/sys/i386/i386/trap.c:1006
#17 0xc09ffc90 in Xint0x80_syscall ()
at /usr/src/sys/i386/i386/exception.s:196
#18 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)

-- 
Pascal Hofstee <caelian_at_gmail.com>