Softupdate/kernel panic ffs_fsync

I have seen a few (unresolved) questions similar to this searching
(google|archives). On a 5.2.1-Release-P2 system (actually a couple with
essentially identical configs) I get the following Stack Backtrace
messages:

backtrace(c070cbf8,2,e5b3af60,0,22) at backtrace +0x17
getdirtybuf(f7f99bbc,0,1,e5b3a,f60,1) at getdirtybuf +0x30
flush_deplist(c724e64c,1,f7f99be4,f7f99be8,0) at flush_deplist +0x43
flush_inode_deps(c6c35000,5c108,f7f99c10,c0510fe3,f7f99c40) at
flush_inode_deps + 0xa3
softdep_sync_metadata(f7f99ca8,0,c06da90f,124,0) at
softdep_sync_metadata +0x87
ffs_fsync(f7f99ca8,0,c06d0c8b,beb,0) at ffs_fsync +0x3b9
fsync(c7c224780,f7f99d14,c06e15c0,3ee,1) at fsync +0x151
syscall(80e002f,bfbf002f,bfbf0028,0,80f57e0) at syscall +0x2a0
Xint0x80_syscall() at Xint0x80_syscall() +0x1d
--- syscall (95), eip=0x282a89af, esp=0xbfbfa10c, ebp=0xbfbfba68 ---


The systems in question are mail servers that act as gateways (no local
delivery) running mimedefang (2.39 - 2.42) with spamassassin. The work
directory is not swap/memory mounted but rather on
/var/spool/MIMEDefang. The frequency of these messages increases when
bayes filtering is added (as the bayes tokens db file also resides on
the same filesystem/directory).

I have read that it may be that getdirtybuf() was passed a corrupt
buffer header; has anything further ever been made of this and if not,
where/how do I start to help contributing to finding a solution?


dmesg:
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 5.2.1-RELEASE-p2 #0: Tue Mar 16 21:59:18 EST 2004
    me_at_myserver:/usr/obj/usr/src/sys/CUSTOM
Preloaded elf kernel "/boot/kernel/kernel" at 0xc0826000.
Preloaded elf module "/boot/kernel/acpi.ko" at 0xc08262bc.
ACPI APIC Table: <PTLTD          APIC  >
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Xeon(TM) CPU 2.00GHz (1996.60-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf27  Stepping = 7
 
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Hyperthreading: 2 logical CPUs
real memory  = 1073217536 (1023 MB)
avail memory = 1032687616 (984 MB)
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
 cpu2 (AP): APIC ID:  6
 cpu3 (AP): APIC ID:  7
ioapic0 <Version 2.0> irqs 0-23 on motherboard
ioapic1 <Version 2.0> irqs 24-47 on motherboard
ioapic2 <Version 2.0> irqs 48-71 on motherboard
Pentium Pro MTRR support enabled
npx0: [FAST]
npx0: <math processor> on motherboard
npx0: INT 16 interface
acpi0: <PTLTD    RSDT  > on motherboard
pcibios: BIOS version 2.10
Using $PIR table, 25 entries at 0xc00fde30
acpi0: Power Button (fixed)
Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x1008-0x100b on acpi0
acpi_cpu0: <CPU> on acpi0
acpi_cpu1: <CPU> on acpi0
pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
pci0: <unknown> at device 0.1 (no driver attached)
pcib1: <ACPI PCI-PCI bridge> at device 2.0 on pci0
pcib1: could not get PCI interrupt routing table for \\_SB_.PCI0.HLB_ -
AE_NOT_FOUND
pci1: <ACPI PCI bus> on pcib1
pci1: <base peripheral, interrupt controller> at device 28.0 (no driver
attached)
pcib2: <ACPI PCI-PCI bridge> at device 29.0 on pci1
pci2: <ACPI PCI bus> on pcib2
em0: <Intel(R) PRO/1000 Network Connection, Version - 1.7.19> port
0x3000-0x301f mem 0xfc200000-0xfc21ffff,0xfc220000-0xfc23ffff irq 54 at
device 3.0 on pci2
em0:  Speed:N/A  Duplex:N/A
pci1: <base peripheral, interrupt controller> at device 30.0 (no driver
attached)
pcib3: <ACPI PCI-PCI bridge> at device 31.0 on pci1
pci3: <ACPI PCI bus> on pcib3
ahc0: <Adaptec aic7899 Ultra160 SCSI adapter> port 0x4000-0x40ff mem
0xfc300000-0xfc300fff irq 32 at device 2.0 on pci3
aic7899: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs
ahc1: <Adaptec aic7899 Ultra160 SCSI adapter> port 0x4400-0x44ff mem
0xfc301000-0xfc301fff irq 33 at device 2.1 on pci3
aic7899: Ultra160 Wide Channel B, SCSI Id=7, 32/253 SCBs
uhci0: <Intel 82801CA/CAM (ICH3) USB controller USB-A> port
0x2000-0x201f irq 16 at device 29.0 on pci0
usb0: <Intel 82801CA/CAM (ICH3) USB controller USB-A> on uhci0
usb0: USB revision 1.0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
uhci1: <Intel 82801CA/CAM (ICH3) USB controller USB-B> port
0x2020-0x203f irq 19 at device 29.1 on pci0
usb1: <Intel 82801CA/CAM (ICH3) USB controller USB-B> on uhci1
usb1: USB revision 1.0
uhub1: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub1: 2 ports with 2 removable, self powered
uhci2: <Intel 82801CA/CAM (ICH3) USB controller USB-C> port
0x2040-0x205f irq 18 at device 29.2 on pci0
usb2: <Intel 82801CA/CAM (ICH3) USB controller USB-C> on uhci2
usb2: USB revision 1.0
uhub2: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub2: 2 ports with 2 removable, self powered
pcib4: <ACPI PCI-PCI bridge> at device 30.0 on pci0
pci4: <ACPI PCI bus> on pcib4
pci4: <display, VGA> at device 4.0 (no driver attached)
fxp0: <Intel 82550 Pro/100 Ethernet> port 0x5400-0x543f mem
0xfc420000-0xfc43ffff,0xfc401000-0xfc401fff irq 22 at device 5.0 on pci4
fxp0: Ethernet address 00:30:48:24:ca:e5
miibus0: <MII bus> on fxp0
inphy0: <i82555 10/100 media interface> on miibus0
inphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
isab0: <PCI-ISA bridge> at device 31.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <Intel ICH3 UDMA100 controller> port
0x2060-0x206f,0x374-0x377,0x170-0x177,0x3f4-0x3f7,0x1f0-0x1f7 mem
0xfc000000-0xfc0003ff at device 31.1 on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata0: [MPSAFE]
ata1: at 0x170 irq 15 on atapci0
ata1: [MPSAFE]
pci0: <serial bus, SMBus> at device 31.3 (no driver attached)
acpi_button0: <Power Button> on acpi0
atkbdc0: <Keyboard controller (i8042)> port 0x64,0x60 irq 1 on acpi0
sio0 port 0x3f8-0x3ff irq 4 on acpi0
sio0: type 16550A
sio1 port 0x2f8-0x2ff irq 3 on acpi0
sio1: type 16550A
fdc0: <Enhanced floppy controller (i82077, NE72065 or clone)> port
0x3f7,0x3f0-0x3f5 irq 6 drq 2 on acpi0
fdc0: FIFO enabled, 8 bytes threshold
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
ppc0 port 0x778-0x77f,0x378-0x37f irq 7 drq 3 on acpi0
ppc0: SMC-like chipset (ECP/EPP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/9 bytes threshold
ppbus0: <Parallel port bus> on ppc0
lpt0: <Printer> on ppbus0
lpt0: Interrupt-driven port
ppi0: <Parallel I/O> on ppbus0
pmtimer0 on isa0
orm0: <Option ROMs> at iomem
0xe0000-0xe3fff,0xdc000-0xdffff,0xc8000-0xc8fff,0xc0000-0xc7fff on isa0
sc0: <System console> on isa0
sc0: VGA <16 virtual consoles, flags=0x200>
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on
isa0
Timecounters tick every 10.000 msec
Waiting 5 seconds for SCSI devices to settle
GEOM: create disk da0 dp=0xc6b99c50
da0 at ahc1 bus 0 target 3 lun 0
da0: <IBM IC35L018UWD210-0 S5CS> Fixed Direct Access SCSI-3 device
da0: 160.000MB/s transfers (80.000MHz, offset 63, 16bit), Tagged
Queueing Enabled
da0: 17501MB (35843670 512 byte sectors: 255H 63S/T 2231C)
SMP: AP CPU #3 Launched!
SMP: AP CPU #1 Launched!
SMP: AP CPU #2 Launched!
Mounting root from ufs:/dev/da0s1a


Thanks,

Sven