Fatal trap 12: page fault while in kernel mode

[Jeremy Gaddis]

One of my machines spontaneously rebooted today, during a run
of `portsdb -Uu` after a cvsup of the ports collection.  It's
also done it a few times before, but I wasn't around and wasn't
able to catch anything that it spit it before it rebooted.  I
was able to reproduce it, and here's what was output before the
reboot:

Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0xc0f95240
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0xc018306c
stack pointer           = 0x10:0xc40aaba4
frame pointer           = 0x10:0xc40aabc4
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 2550 (sh)
interrupt mask          = none
trap number             = 12
panic: page fault

[jeremy at PLUTO:ttyp0:~]$ uname -a
FreeBSD pluto.main.gaddis.org 4.8-STABLE FreeBSD 4.8-STABLE #0: Sun Jun 
1 01:12:47 EST 2003    
root at jupiter.main.gaddis.org:/usr/obj/usr/src/sys/PLUTO  i386

[jeremy at PLUTO:ttyp0:~]$ dmesg
Copyright (c) 1992-2003 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 4.8-STABLE #0: Sun Jun  1 01:12:47 EST 2003
    root at jupiter.main.gaddis.org:/usr/obj/usr/src/sys/PLUTO
Timecounter "i8254"  frequency 1193182 Hz
Timecounter "TSC"  frequency 199310034 Hz
CPU: Pentium/P54C (199.31-MHz 586-class CPU)
  Origin = "GenuineIntel"  Id = 0x52c  Stepping = 12
  Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>
real memory  = 33554432 (32768K bytes)
config> di ppc0
No such device: ppc0
Invalid command or syntax.  Type `?' for help.
config> di bt0
No such device: bt0
Invalid command or syntax.  Type `?' for help.
config> di aic0
No such device: aic0
Invalid command or syntax.  Type `?' for help.
config> di aha0
No such device: aha0
Invalid command or syntax.  Type `?' for help.
config> di adv0
No such device: adv0
Invalid command or syntax.  Type `?' for help.
config> en ed0
No such device: ed0
Invalid command or syntax.  Type `?' for help.
config> po ed0 0x300
No such device: ed0
Invalid command or syntax.  Type `?' for help.
config> ir ed0 10
No such device: ed0
Invalid command or syntax.  Type `?' for help.
config> iom ed0 0xd8000
No such device: ed0
Invalid command or syntax.  Type `?' for help.
config> f ed0 0
No such device: ed0
Invalid command or syntax.  Type `?' for help.
config> q
avail memory = 29859840 (29160K bytes)
Preloaded elf kernel "kernel" at 0xc02ea000.
Preloaded userconfig_script "/boot/kernel.conf" at 0xc02ea09c.
Intel Pentium detected, installing workaround for F00F bug
md0: Malloc disk
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Host to PCI bridge> on motherboard
pci0: <PCI bus> on pcib0
isab0: <Intel 82371SB PCI to ISA bridge> at device 7.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <Intel PIIX3 ATA controller> port 0xf000-0xf00f at device 7.1
on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
pci0: <SiS 6326 SVGA controller> at 19.0
rl0: <Accton MPX 5030/5038 10/100BaseTX> port 0x6100-0x61ff mem
0xe0810000-0xe08100ff irq 11 at device 20.0 on pci0
rl0: Ethernet address: 00:e0:29:96:62:f9
miibus0: <MII bus> on rl0
rlphy0: <RealTek internal media interface> on miibus0
rlphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
orm0: <Option ROM> at iomem 0xc0000-0xc7fff on isa0
fdc0: <NEC 72065B or clone> at port 0x3f0-0x3f5,0x3f7 irq 6 drq 2 on
isa0
fdc0: FIFO enabled, 8 bytes threshold
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
kbd0 at atkbd0
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on
isa0
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
sio1 at port 0x2f8-0x2ff irq 3 on isa0
sio1: type 16550A
ad0: 19541MB <Maxtor 5T020H2> [39704/16/63] at ata0-master WDMA2
acd0: CDROM <BCD-44XH CD-ROM> at ata1-master PIO4
Mounting root from ufs:/dev/ad0s1a
WARNING: / was not properly dismounted
[jeremy at PLUTO:ttyp0:~]$

The box in question is a P200 w/ 32 MB of RAM and 20 GB HDD,
running 4.8-STABLE.

I'd appreciate any comments or suggestions as to what I might
do to track down the source of this problem.

Thanks,
j.

-- 
Jeremy L. Gaddis   <jeremy at gaddis.org>   <http://www.gaddis.org>