Created attachment 134100 [details]
relevant dmesg output

Sorry for the non-descriptive bug title in advance, I'm not sure which parts of the logs are worth a bug report, but I'm moderately sure that something in here deserves a bug filed.

My machine is a Lenovo P50 with:

    VGA compatible controller: NVIDIA Corporation GM107GLM [Quadro M2000M] (rev a2)

And mesa version 17.1.8

I connected an external monitor to the HDMI port, and I got black screens for a few retries.

On an unrelated (maybe not so unrelated?) note, I get reproducible FAULTs on startup, regardless of any monitor attached or not I believe. I also got some others on today's log, but that may be just related to the problem above. The first two lines below repro even without an external monitor:

    [    2.690083] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 022554 [ IBUS ]
    [    2.691514] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 10ac08 [ IBUS ]
    [   23.396822] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 690000 [ TIMEOUT ]
    [   41.791019] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 690000 [ TIMEOUT ]
    [   41.791902] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 6900c0 [ TIMEOUT ]
    [   51.876682] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 690000 [ TIMEOUT ]
    [   61.915247] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 690000 [ TIMEOUT ]
    [   75.297725] nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 690000 [ TIMEOUT ]

Happy to help providing more information, testing, or even trying to contribute a fix (with some guidance ideally, since I know nothing about the driver's code :P).

Thanks a lot in advance.