NFS server problems (lockup) on netbsd-5

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hello,
I tried upgrading a NFS server to today's netbsd-5 branch, without success.
The previous kernel (netbsd-5 from 7 feb 2010) is rock solid.
I tried a kernel from before the recent nfs-related pullups, it shows
the same symptoms.

After a few hours of operation, the network stack is locked up.
The server doesn't reply to ping, but the console is still alive and
I can log in (it doesn't always make it to the shell though).
ps from ddb shows lots of processes waiting on tstile, the lock seems to
be the softnet_lock. One of the nfsd thread is waiting on livelock, I suspect
it's also trying to get the softnet_lock but with a tryenter/kpause.

unfortunably I don't have a core dump (I couldn't get one).

Any idea about what could be going on ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--