Panics/reboots with Varnish

[Eirik Øverby]

Hi all,

I'm running a server (fbsd-amd64, 6.2-STABLE) with a bunch of jails  
(~10). A couple of these are seeing pretty heavy HTTP traffic, so I  
threw in a varnishd in each of the two main offenders, each using the  
httpd in the same jail as back-end. Then I use pf on the host to NAT  
incoming requests to <jail>:http to <jail>:varnishdport .

Now this does indeed lessen the load on the server quite  
dramatically, and also leads to positive reports from users whenever  
this is switched on. I can globally enable/disable this with pfctl -e/ 
pfctl -d, or by modifying+reloading pf config files. In other words -  
when it works, it works great.

Problem: Whenever this is in effect, the box rarely stays up for >48  
hours. Without this in effect, it can stay up for >30 days. I've been  
playing with this since the day varnish 1.0 was released, and from  
what I can tell this is consistent behavior.

I don't have any coredumps - it appears as if the server is just  
booting. I do have a core dump from another situation (where I used a  
mismatched raid controller driver, causing a known panic), so I know  
the whole dump stuff works as it should. I have also swapped memory  
with no change in behavior.

Does anyone have any idea what can be causing this? Which edge cases  
might be touched by varnish that I'm not seeing elsewhere? I can see  
the box is swapping a bit from time to time, but nothing dramatic,  
and that is as it should be, just the kernel doing its job.

Thanks,
/Eirik