And it happened again today... I have no idea what triggered it this
time, I went outside, and when I came back, it had crashed and
rebooted. Nothing was scheduled to run at the time, and I wasn't doing
anything with it... the instruction pointer is at exactly the same
place as in my original report. Looks like the same crash to me :)

The machine is now running:
NetBSD sloth.metonymy.com 1.3_ALPHA NetBSD 1.3_ALPHA (SLOTH) #140: Sun Nov  2 04:36:24 CST 1997     khym@dahan.metonymy.com:/usr/src.local/sys/arch/i386/compile/SLOTH i386

vm_fault(0xf068a600, 0, 1, 0) -> 5
fatal page fault in supervisor mode
trap type 6 code f0250000 eip f01a011b cs f1a50008 eflags 10246 cr2 0 cpl e00044c2
panic: trap
syncing disks... 3 3 1 done

dumping to dev 1, offset 32641
dump 8 7 6 5 4 3 2 1 succeeded


rebooting...

(gdb) list *0xf01a011b
0xf01a011b is in pmap_changebit (../../../../arch/i386/i386/pmap.c:1646).
1641                                    if (va >= pager_sva && va < pager_eva)
1642                                            continue;
1643                            }
1644    
1645                            pte = pmap_pte(pv->pv_pmap, va);
1646                            *pte = (*pte & maskbits) | setbits;
1647                    }
1648                    pmap_update();
1649            }
1650            splx(s);

Name: Dave Huang     |   Mammal, mammal / their names are called /
INet: khym@bga.com   |   they raise a paw / the bat, the cat /
FurryMUCK: Dahan     |   dolphin and dog / koala bear and hog -- TMBG
Dahan: Hani G Y+C 22 Y++ L+++ W- C++ T++ A+ E+ S++ V++ F- Q+++ P+ B+ PA+ PL++