>> OK.  The crash point in net/radix.c:rn_match() is at least plausible.
>> I don't know why the stack looks hosed, though.  My initial guess is
>> some kind of memory corruption.  My second is that something has
>> corrupted the radix tree.

I've thought about this, and this happened when the ethernet interface was 
in promiscuous mode (I was running tcpdump so I could report the DDoS 
drones to the network admins).

Something I thought was very strange was that every time I either started 
or stopped tcpdump, the whole system completely stopped communicating for 
sometimes up to 30 seconds. I wonder if either of these things are related 
to the crash...

John