RPC: multiple fragments per record not supported

[Simon Kirby <sim@hostway.ca>]

Hello!

With 2.6.28.10 and 2.6.29.4 knfsd after a few hours of heavy concurrent
NFSv3 write loads (migration of Maildirs with rsync), we are seeing this
error:

	kernel: RPC: multiple fragments per record not supported

...followed by knfsd immediately ignoring all further requests. 
Restarting knfsd (/etc/init.d/nfs-kernel-server restart) seems to make
it start responding and work as normal again.

"ps -eo pid,stat,args,wchan" during the event shows all nfsd processes
sleeping in "svc_recv":

22714 S<   [nfsd]                      svc_recv

This client with the high write load is an old 2.6.17 kernel, mounting
the server with rw,nolock,hard,intr,timeo=9,retrans=3,rsize=8192,wsize=8192
(jumbo frames are enabled).

Is this any sort of known issue?  I'm trying to reproduce it in a testing
environment.

Cheers,

Simon-