There are a couple of related bugs already open. The VM fault seems to have appeared with more recent kernels, I can get those now even without locking. If you leave valley for a couple of minutes after lock you will likely get a hung task trace like those in the bugs below (Though not a GPU reset as that is not enabled on more recent kernels) It would probably be best to mark this bug a DUP of one of these. https://bugs.freedesktop.org/show_bug.cgi?id=91278 https://bugs.freedesktop.org/show_bug.cgi?id=91790