Comment 2 for bug 1803353

Extra information: sudo kill -9 <pid-of-xorg-process> via ssh connection did restore the display in working order without restarting the system so I'm pretty sure this is caused by some kind of hang caused by xorg process. Plain kill without -9 did not do anything, though.

Perhaps this is caused by some race conditition while xorg is keeping some locks which cause keyboard not to work (e.g. Alt+Ctrl+F1) and the display does not update.

After saying that, the system seems to be in some weird state where pretty much all my old X client processess are still running (e.g. Chrome, Opera, Thunderbird) even though the original xorg process does not exists anymore. Thunderbird seems to be eating 100% of a single core.