semi-frequent 5.0_BETA crashes on SGI O2

Folks:
	For several weeks now, my O2, running 4.99.72 and now 5.0_BETA
	has locked up hard at various points, frequently it seems during
	nightly/weekly script processing.  Most of the time it simply
	locks hard and needs to be rebooted with a paperclip, but I did
	get a DIAGNOSTIC panic the other day (after adding LOCKDEBUG,
	DEBUG and DIAGNOSTIC to the kernel).  Of course, it looks like
	it locked up last night as well :(

	The panic seen last night was the following; the kernel was built
	from 5.0 branch sources of ~ Dec 15th.

panic: kernel diagnostic assertion "c->c_magic == CALLOUT_MAGIC" failed: file "/
extra/netbsd-src/netbsd-5/sys/kern/kern_timeout.c", line 424
Stopped in pid 0.2 (system) at  netbsd:cpu_Debugger+0x4:        jr      ra
                bdslot: nop
db> tr
cpu_Debugger+4 (8dffe000,bf390000,0,0) ra 8032a0e4 sz 0
panic+1e4 (8dffe000,805259f0,805558dc,805558a8) ra 804c6e18 sz 48
__kernassert+48 (8dffe000,805259f0,805558dc,805558a8) ra 80311fa0 sz 32
callout_stop+108 (8dffe000,805259f0,805558dc,805558a8) ra 8012bd98 sz 32
ahc_done+c4 (8dffe000,805259f0,805558dc,805558a8) ra 801217e0 sz 72
ahc_run_qoutfifo+104 (8dffe000,a,805558dc,805558a8) ra 80411df0 sz 48
ahc_intr+ac (8dffe000,a,805558dc,805558a8) ra 804033cc sz 48
mace_intr+64 (8dffe000,a,805558dc,805558a8) ra 80400828 sz 48
crime_intr+148 (8dffe000,a,805558dc,805558a8) ra 803f9a4c sz 56
cpu_intr+124 (8dffe000,a,805558dc,805558a8) ra 803d6f30 sz 48
mips3_KernIntr+90 (0,80549ccc,1cd,80549d04) ra 803dee2c sz 128
cpu_idle+28 (0,80549ccc,1cd,80549d04) ra 802e9b18 sz 24
idle_loop+248 (0,80549ccc,1cd,80549d04) ra 803d75b0 sz 56
mips3_lwp_trampoline+20 (0,80549ccc,1cd,80549d04) ra 0 sz 24
User-level: pid 0.2

	Anyone seen this / have an clues?  I didn't have a lot of time
	to dig into it at the time, but I do have a coredump I can dig
	into.

Thanks,
--rafal

-- 
  Time is an illusion; lunchtime, doubly so.     |/\/\|           Rafal Boni
                   -- Ford Prefect               |\/\/|      [email protected]