(Sorry if I sent this mail twice, I'm having troubles with my mail
client)
I've experienced locks too, nothing in logs that I could find,
but after swaping back to the main kernel, from linux-ck, everything was
fine. Maybe this is related for you too? The update that caused the
lockups seems to match
http://ck-hack.blogspot.fr/2016/09/bfs-497-linux-47-ck4.html
Alas I still have no explanation for the random lockups some people
are seeing, but I have seen reports of it happening on mainline
kernels as well now, so while I'm always suspicious of my own code,
there is also the chance that BFS exacerbates an issue in mainline.
Something that appears common is onboard Intel graphics with the
Haswell chipset.
https://aur.archlinux.org/cgit/aur.git/log/?h=linux-ck
