There was at least one NFS client in the NFS connectathon event which would fail in the locking test. This was diagnosed to be because gluster's NLM does not implement the TEST_MSG procedure.
To be clear, it is the lack of the full set of *_MSG procedures. The failure is visible upfront in the TEST_MSG procedure.
The *_MSG procedures are for the asynchronous requests and responses. The procedures are documented here: - http://pubs.opengroup.org/onlinepubs/009629799/chap10.htm#tagcjh_11_03
because of the large number of bugs filed against mainline version\ is ambiguous and about to be removed as a choice. If you believe this is still a bug, please change the status back to NEW and choose the appropriate, applicable version for it.