I can't imagine there isn't a simple strategy to solve this issue of stale nfs handles preventing a machine from shutting down normally, but I'm not sure what that would be. It's pretty annoying to have to force a reboot just because a wifi connection dropped out at some point while watching endless 'waiting for nfsmount' messages.
What are your mount options?
You should experiment with "
Using "soft" is usually advised against, it can result in written data being lost. It's safe to use as read-only.
On latter linux kernels (2.6.25) NFS clients "intr" is deprecated, sigkill should just work. "