'panic: lockmgr: upgrade exclusive lock' when rebooting

Running 6.0 from a few days ago, so you may have already fixed this.

Apr 12 07:37:45 haessal reboot: rebooted by root
Apr 12 07:37:47 haessal syslogd: exiting Waiting (max 60 seconds) for system process `vnlru' to stop...done
Waiting (max 60 seconds) for system process `syncer' to stop...timed out
Waiting (max 60 seconds) for system process `bufdaemon' to stop...done
panic: lockmgr: upgrade exclusive lock
cpuid = 0
KDB: enter: panic
[thread pid 92797 tid 100297 ]
Stopped at      kdb_enter+0x30: leave
db> wh
Tracing pid 92797 tid 100297 td 0xc3b30600
kdb_enter(c0741b61,0,c073fd33,ee2f6ac4,c3b30600) at kdb_enter+0x30
panic(c073fd33,0,c073fc14,b5,c89d3670) at panic+0x13e
debuglockmgr(c89d3670,2004,c89d36b0,c3b30600,c074ad3e) at debuglockmgr+0x336
vop_stdlock(ee2f6bb8,8,c3b30600,ee2f6b58,c054f845) at vop_stdlock+0x4e
VOP_LOCK_APV(c0790c40,ee2f6bb8,ee2f6ba0,c07117a5,ee2f6bb8) at VOP_LOCK_APV+0x9e
ffs_lock(ee2f6bb8,c0762ba4,36,c0762b83,c89d3618) at ffs_lock+0x19
VOP_LOCK_APV(c07906e0,ee2f6bb8,c074b5e7,782,c079f9c0) at VOP_LOCK_APV+0x9e
vput(c89d3618,2,c07a5cc0,454,c3615860) at vput+0x15c
ffs_sync(c3615800,2,c07a5cc0,c07a5cc0,c3615800) at ffs_sync+0x1dd
sync(c07a5cc0,0,c0741b85,10d,c055cb74) at sync+0x100
boot(0,0,c0741b85,a2,ee2f6d40) at boot+0x2a1
reboot(c3b30600,ee2f6d14,3a6,c075ef20,c3b30600) at reboot+0x47
syscall(2f,2f,2f,1c,0) at syscall+0x2c4
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (55, FreeBSD ELF32, reboot), eip = 0x280a779f, esp = 0xbfbfec1c, ebp = 0xbfbfec74 ---
db> show lockedvnods
Locked vnodes
panic: _mtx_lock_sleep: recursed on non-recursive mutex lockbuilder mtxpool _at_ ../../../kern/kern_lock.c:540

cpuid = 0
Uptime: 1d17h30m4s
Dumping 2047 MB

Dump failed. Partition too small.
Automatic reboot in 15 seconds - press a key on the console to abort

(Dammit)

Kris