https://bugs.freedesktop.org/show_bug.cgi?id=104362
--- Comment #18 from nmr nnmmrr88+fd@gmail.com --- Created attachment 143124 --> https://bugs.freedesktop.org/attachment.cgi?id=143124&action=edit dmesg during reboot/recovery
On the basis that it may be shader induced I repro'd a similar hang with dxvk (v0.95-5-gcc38412).
FWIW here's dmesg during subsequent GPU recovery (which fails :( ) and reboot (which hangs.) It appears hung on a DMA, and/or hung doing a modeset, acquiring the modeset lock.