Panic mounting root (bundirty) on yesterday's -CURRENT

Hi all,

I upgraded my ancient ThinkPad 380D from some 5.2-CURRENT to yesterdays
6.0-CURRENT.  Booting GENERIC I get:

Mounting root from ufs:/dev/ad0s2a
g_vfs_done():ad0s2a[WRITE(offset=65536, length=8192)]error = 1
panic: bundirty: buffer 0xc290a170 still on queue 1

With a custom kernel (no INVARIANTS or WITNESS) I still get the
g_vfs_done() message, but no panic, and the machine seems to run normally.
I see somebody else was asking about the same message here yesterday:
http://lists.freebsd.org/pipermail/freebsd-current/2004-November/043012.html

Any ideas?  Full dmesg and traceback from DDB below.  Unfortunately I
haven't been able to get remote debugging working on this machine (it hangs
at the boot: prompt with -d in /boot.config) so I don't know what further
debugging I can do...

Cheers,

	Scott

----- cut here -----
GDB: no debug ports present
KDB: debugger backends: ddb
KDB: current backend: ddb
Copyright (c) 1992-2004 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
	The Regents of the University of California. All rights reserved.
FreeBSD 6.0-CURRENT #0: Sat Nov 13 16:18:14 GMT 2004
    scott_at_tuatara.fishballoon.org:/local/obj/local/-CURRENT/src/sys/GENERIC
WARNING: WITNESS option enabled, expect reduced performance.
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Pentium/P54C (152.13-MHz 586-class CPU)
  Origin = "GenuineIntel"  Id = 0x52c  Stepping = 12
  Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>
real memory  = 33554432 (32 MB)
avail memory = 23445504 (22 MB)
Intel Pentium detected, installing workaround for F00F bug
npx0: [FAST]
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Host to PCI bridge> pcibus 0 on motherboard
pci0: <PCI bus> on pcib0
pci0: <bridge, PCI-unknown> at device 1.0 (no driver attached)
pci0: <display, VGA> at device 3.0 (no driver attached)
pci0: <bridge, PCI-PCMCIA> at device 19.0 (no driver attached)
cpu0 on motherboard
isa0: <ISA bus> on motherboard
orm0: <ISA Option ROM> at iomem 0xc0000-0xc7fff on isa0
pmtimer0 on isa0
ata0 at port 0x3f6,0x1f0-0x1f7 irq 14 on isa0
ata1 at port 0x376,0x170-0x177 irq 15 on isa0
atkbdc0: <Keyboard controller (i8042)> at port 0x64,0x60 on isa0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
atkbd0: [GIANT-LOCKED]
psm0: <PS/2 Mouse> irq 12 on atkbdc0
psm0: [GIANT-LOCKED]
psm0: model Generic PS/2 mouse, device ID 0
fdc0: <Enhanced floppy controller> at port 0x3f0-0x3f5 irq 6 drq 2 on isa0
fdc0: [FAST]
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
ppc0: <Parallel port> at port 0x3bc-0x3c3 irq 7 on isa0
ppc0: Generic chipset (ECP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/8 bytes threshold
ppbus0: <Parallel port bus> on ppc0
plip0: <PLIP network interface> on ppbus0
lpt0: <Printer> on ppbus0
lpt0: Interrupt-driven port
ppi0: <Parallel I/O> on ppbus0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 16550A, console
sio1: configured irq 3 not in bitmap of probed irqs 0
sio1: port may not be enabled
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
unknown: <PNP0303> can't assign resources (port)
unknown: <PNP0f13> can't assign resources (irq)
unknown: <PNP0700> can't assign resources (port)
unknown: <PNP0600> can't assign resources (port)
unknown: <PNP0401> can't assign resources (port)
unknown: <PNP0501> can't assign resources (port)
Timecounter "TSC" frequency 152132018 Hz quality 800
Timecounters tick every 1.000 msec
ad0: 1376MB <IBM-DMCA-21440/A73A95> [2796/16/63] at ata0-master PIO4
acd0: CDROM <CD-38E/1.0D> at ata0-slave PIO4
Mounting root from ufs:/dev/ad0s2a
g_vfs_done():ad0s2a[WRITE(offset=65536, length=8192)]error = 1
panic: bundirty: buffer 0xc290a170 still on queue 1
cpuid = 0
KDB: enter: panic
[thread 100063]
Stopped at      kdb_enter+0x2c: leave   
db> tr
kdb_enter(c080e5a0,100,c126d480,c290a170,c290a170) at kdb_enter+0x2c
panic(c08158f0,c290a170,1,c290a170,c44a26bc) at panic+0x17f
bundirty(c290a170,0,c08157f8,ed2,c290a170) at bundirty+0xbd
brelse(c290a170,c290a170,c290a170,2090022,0) at brelse+0x7ba
bufwrite(c290a170) at bufwrite+0x3b8
getblk(c1284cf0,80,0,4000,0) at getblk+0x175
breadn(c1284cf0,80,0,4000,0) at breadn+0x2e
bread(c1284cf0,80,0,4000,0,c44a283c) at bread+0x20
ffs_vget(c1270c00,80,2,c44a28c4) at ffs_vget+0x20d
ufs_lookup(c44a2974) at ufs_lookup+0x81e
vfs_cache_lookup(c44a29e4,c080d96f,c44a2bf8,c126d480,0) at vfs_cache_lookup+0x25d
lookup(c44a2be4,c126d480,c08d8840,c44a2a2c,c062adb5) at lookup+0x269
namei(c44a2be4,c062ade4,c126d480,c08dee40,2) at namei+0x215
vn_open_cred(c44a2be4,c44a2ce4,0,c112a180,3) at vn_open_cred+0x145
vn_open(c44a2be4,c44a2ce4,0,3,c08cf980,8,c0817888,3bc) at vn_open+0x1e
kern_open(c126d480,2807ade4,0,1,0) at kern_open+0xd7
open(c126d480,c44a2d14,3,e,286) at open+0x18
syscall(2f,2f,2f,28085000,8048d51) at syscall+0x128
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (5, FreeBSD ELF32, open), eip = 0x2806a14b, esp = 0xbfbfec54, ebp = 0xbfbfed00 ---
db> panic
panic: from debugger
cpuid = 0
Uptime: 4s
Cannot dump. No dump device defined.
Automatic reboot in 15 seconds - press a key on the console to abort

-- 
===========================================================================
Scott Mitchell           | PGP Key ID | "Eagles may soar, but weasels
Cambridge, England       | 0x54B171B9 |  don't get sucked into jet engines"
scott at fishballoon.org | 0xAA775B8B |      -- Anon