https://bugs.freedesktop.org/show_bug.cgi?id=99089
--- Comment #2 from Witold Baryluk witold.baryluk+freedesktop@gmail.com --- The kernel update might be possibility.
I am now running 4.9.0 custom built, and the system / screen is not freezing, but instead sometimes Xorg crashes, usually when clicking something. I am able to reproduce it reliably on some webpages in chrome, when clicking specifying button (dmesg shows X11 segfault, but entire Xorg exits, and I need to relogin). I was able to also reproduce it in few other programs like VLC, but less reliably.
Probably a different issue.
It is also possibly that my Xorg server is now confused, and uses i915 instead of radeon (ThinkPad W500 has both), but dmesg and xorg.0.log claims I am using radeon, but glxinfo shows there is no hardware opengl acceleration (llvmpipe instead). Weird.
I will try to reproduce it again, maybe on 4.8 kernel again.