panic: unmount: dangling vnode

[Rumko]

I had a ntfs read-only mount and copied a few files off of it. After that I
tried unmounting it, which resulted in the panic mentioned in the subject. The
core is available at leaf:~rumko/crash/vnode/*.6 and the kernel was from about
31st Jan.

Unread portion of the kernel message buffer:
panic: unmount: dangling vnode
mp_lock = 00000000; cpuid = 0
Trace beginning at frame 0xf32f1c24
panic(f32f1c48,f32f1c58,d9e6bdd8,0,f32f1c6c) at panic+0x14d
panic(c0440231,0,d9e6bdf8,1,10001001) at panic+0x14d
dounmount(d9e6bdd8,0,0,0,0) at dounmount+0x2da
sys_unmount(f32f1cf0,6,206d1,0,c0496228) at sys_unmount+0x13c
syscall2(f32f1d40) at syscall2+0x3ac
Xint0x80_syscall() at Xint0x80_syscall+0x36
boot() called on cpu#0
Uptime: 7d18h39m25s
Physical memory: 3065 MB
Dumping 344 MB: 329 313 297 281 265 249 233 217 201 185 169 153 137 121 105 89
73 57 41 25 9

Reading symbols from /boot/modules/if_nfe.ko...done.
Loaded symbols for /boot/modules/if_nfe.ko
Reading symbols from /boot/modules/powernow.ko...done.
Loaded symbols for /boot/modules/powernow.ko
Reading symbols from /boot/modules/linprocfs.ko...done.
Loaded symbols for /boot/modules/linprocfs.ko
Reading symbols from /boot/modules/if_bridge.ko...done.
Loaded symbols for /boot/modules/if_bridge.ko
Reading symbols from /boot/modules/linux.ko...done.
Loaded symbols for /boot/modules/linux.ko
Reading symbols from /boot/modules/ntfs.ko...done.
Loaded symbols for /boot/modules/ntfs.ko
_get_mycpu (di=0xc04d9de0) at ./machine/thread.h:83
83          __asm ("movl %%fs:globaldata,%0" : "=r"
(gd) : "m"(__mycpu__dummy));
(kgdb) bt
#0  _get_mycpu (di=0xc04d9de0) at ./machine/thread.h:83
#1  md_dumpsys (di=0xc04d9de0)
at /usr/src/sys/platform/pc32/i386/dump_machdep.c:264
#2  0xc01e45c2 in dumpsys () at /usr/src/sys/kern/kern_shutdown.c:838
#3  0xc01e4b94 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:387
#4  0xc01e50f2 in panic (fmt=0xc0440231 "unmount: dangling vnode")
at /usr/src/sys/kern/kern_shutdown.c:744
#5  0xc02449f4 in dounmount (mp=0xd9e6bdd8, flags=0)
at /usr/src/sys/kern/vfs_syscalls.c:783
#6  0xc0244ca0 in sys_unmount (uap=0xf32f1cf0)
at /usr/src/sys/kern/vfs_syscalls.c:618
#7  0xc0403b90 in syscall2 (frame=0xf32f1d40)
at /usr/src/sys/platform/pc32/i386/trap.c:1366
#8  0xc03ef4b6 in Xint0x80_syscall ()
at /usr/src/sys/platform/pc32/i386/exception.s:876
#9  0x0000001f in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
-- 
Regards,
Rumko