Comment 4 for bug 1640663

The Ubuntu 14.04 kernel contains a recent enough version of the openvswitch datapath module to not need to use the dkms package any longer - and later HWE kernels also work fine.

So I'd recommend uninstalling -dkms for now:

  https://javacruft.wordpress.com/2014/03/03/which-open-vswitch/