mutex lock panic on halt/shutdown unmounting GPT/RAID filesystem

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

I'm building (built, rather, now testing) a machine to be my new file
server.  I'm using a NetBSD-5.1_STABLE/i386 kernel made from GENERIC
plus "options RF_RAID5_RS=1" to get RAID-5 w/rotated sparing.  The raid
is built across 8 1TB Hitachi SATA drives using a 4-port siisata
(sii3124-based) PCIe card and the onboard ahcisata ports of an intel
D945GCL board.  The system disk is on the parallel ATA bus.

The machine has 4GB of RAM, although only a little over 3.5GB is
actually visible, naturally.  As such, I only defined a token 2GB
of swap space.

I have the RAID in a single filesystem defined using GPT and wedges.
All file systems are mounted with the "log" option.

Prior to having the RAID intialized, newfs'ed and mounted, nothing
appeared amiss.

Once the big filesystem was online, the system will panic when shutting
down (e.g.: shutdown -r now) with "mutex lock error: locking against
myself".  Unfortunately it all goes by too fast to read.  It saves the
crashdump, but I think the subsequent savecore has problems--the memory
image is there, but the kernel image is only 10 bytes in size.  It
displays "(null) bad address".

This appears to happen AFTER the big filesystem is successfully unmounted
but BEFORE the system disk's filesystems have been unmounted.  Console
and dmesg indicates that the OS partitions get the log-replay treatment
when starting up again.  The RAID and its filesystem are intact.

I've determined that if I manually unmount the GPT/RAID filesystem
before shutting down it doesn't panic.

Any clues?

Need more data?

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