With recent kernels if the Kerberos ticket for a nfs4 mount expires any 
user process trying to access the mount hangs until a new ticket is 
obtained.  Simultaneously a (luckily rate-limited, but still seemingly 
endless) stream of "Error: state manager encountered RPCSEC_GSS session 
expired against NFSv4 server" messages is written to the kernel log.

In a common setup with user home directories nfs4 mounted on 
workstations one of the processes that is likely to hang is the 
screen-unlock function which would normally (via pam_krb5 or similar) 
get the new ticket.

In older kernels the EKEYEXPIRED error would be passed to userland, 
which would usualy just give up.

This patch restores the old behavior, which makes nfs4 mounted home 
directories usable for me.