Bug#891056: Reproducible Intel GPU hang on rcs0 with ecode 9:0:0x86dffffd

[Ben Caradoc-Davies]

This bug is also seen in vanilla 4.16.0-rc2 from 3664ce2d930983966d on 
torvalds/master, but with this kernel, the gpu is reset without crashing 
X. After hanging for a few seconds, X recovers.

Kind regards,
--
Ben Caradoc-Davies <b...@transient.nz>
Director
Transient Software Limited <https://transient.nz/>
New Zealand