NFS problems, locking up

I'm still having problems with NFS locking up when moving large amounts of
data over it on 6-CURRENT from 2005.01.11.05.00.00. This problem has
persisted for a long time now, and the only thing that seems to cure it is
running the network stack with giant enabled (debug.mpsafenet=0).

When it happens, the process doing the copying ends up in "nfsaio" state
according to ps. Any accesses to the locked mount by other processes ends up
waiting forever in state "nfs". I have multiple file systems mounted from
the same server, and only the mount where the data is being moved locks up.
The others continue to work as expected.

Server: UP, 6-CURRENT from 2005.01.11.05.00.00, if_vr (POLLING)
Client: SMP (dual AMD MP), 6-CURRENT from 2005.01.11.05.00.00, if_em

The machines are connected with a crossover cable. I've tried both
schedulers (4BSD and ULE) on the client, but it doesn't make any difference
(server is running 4BSD). PREEMPTION is enabled on both server and client.
ADAPTIVE_GIANT is enabled on the client.

/Daniel Eriksson