We've received reports from users of a cifs mount regression in our 4.4-based kernel, e.g. [1]. It is fixed by reverting the follwing commit from 4.8 which was applied to 4.4 stable:
a6b5058 fs/cifs: make share unaccessible at root level mountable Testing against 4.8-rc7 shows that the problem is present there as well. Thanks, Seth [1] http://bugs.launchpad.net/bugs/1626112
