OpenSUSE 13.2 Xen PVM Guest has been running fine with
kernel-xen-3.16.7-42.1.x86_64.

When I applied all the latest patches, and the kernel was upgraded to
kernel-xen-3.16.7-53.1.x86_64, I started getting NFS errors in the log:

2017-01-06T08:33:16.958484-05:00 vm1 kernel: [68165.600204] nfs: server nas1
not responding, timed out
2017-01-06T08:38:20.074869-05:00 vm1 kernel: [68468.704173] nfs: server nas1
not responding, timed out
2017-01-06T08:38:20.074882-05:00 vm1 kernel: [68468.704224] nfs: server nas1
not responding, timed out
2017-01-06T08:43:08.335264-05:00 vm1 kernel: [68756.957090] nfs: server nas1
not responding, timed out

All attempts to access the automounted filesystem would hang.  A reboot would
fix it temporarily but the problem would recur.

I booted the host to the old kernel (kernel-xen-3.16.7-42.1.x86_64) and things
are operating normally with no NFS hangs.  All latest patches have been applied
as of Jan 7, 2017.