The NFS client is prone to loose locks on filesystems when the locking
process is killed with a signal. This has been discussed on the nfs
mailing list in these threads:

  http://sourceforge.net/mailarchive/forum.php?thread_id=3213117&forum_id=4930

  http://marc.theaimsgroup.com/?l=linux-nfs&m=107074045907620&w=2

Marcelo, if the above links are not sufficient, please email back for
more details.

The enclosed patch is from Trond, and it fixes the problem.

Phil.