System hangs due to NFS share

[Sylvain <sylvaintersideral@gmail.com>]

Hi,

I have an NFS share mounted on my Debian testing computer with default
mount options. It works fine but as soon as my computer loses network
access or the NAS is disconnected or shut down, the system becomes
unstable:

- In KDE, everything is frozen (because of the file manager I think)
- If I try to cd to the mountpoint, it makes the console hang forever
- I can't umount the mountpoint, as the umount command hangs. Also the
-f flag doesn't change anything
- I can't even shutdown my computer anymore and I'm forced to use the
magic keys to be able to reboot it

I tried different network managers (wicd, network-manager), different
ways to connect (wifi, wired), and different mount options (using a
hard nfs mount, specifying the retry option) but that didn't help. I
really don't know what to try next and this is really driving me mad.

Thanks,
Sylvain