Bug#440676: nfs-kernel-server: Simultaneous transfer on mirrored nfs mounts causes service freezes

[Moritz Mühlenhoff <muehlenhoff@univention.de>]

Jeffrey B. Green wrote:
> (I've delayed a few weeks in reporting this bug and so unsure whether other
> work on it has already occurred. However I could not find anything
> relevant.)

A very similar behaviour can be reproduced with i386 as well (with the Etch 
versions of  the Linux kernel and nfs-kernel-server):
We have a setup where a block device is replicated with drbd. On this device 
an ext3 partition has been created, which is exported over NFS. Reading from 
the NFS share works fairly well, however concurrent writes to the share lead 
to lockups. The client processes copying data to the share are stalling and 
sometimes the system is locked up requiring a hard reboot.

This is reproducable with both NFS over UDP and NFS over TCP.

I originally assumed this was only triggerable with the block dev on a drbd 
device, but per Jeffrey's mail is seems to be a more widespread problem.

Cheers,
Moritz