(In reply to Mathias Tillman from comment #13)
> Created attachment 117871 [details] [review] [review]
> Potential fix
> 
> Andy: Could you test the attached patch, please? It's now working fine for
> me.

It also seems to be working for me :-)

I just did about 20 startx in a row and all is OK.

va_test behaves the same as before = fail as user from within X, but maybe that
is expected?

modesetting still has issues, but they probably are nothing to do with this bug
anyway - I had never used it before this issue arose.