Re: [bug report] Commit ccf953d8f3d6 ("fb_defio: Remove custom address_space_operations") breaks Hyper-V FB driver

On 6/4/2021 9:00 AM, Wei Liu wrote:

On Fri, Jun 04, 2021 at 02:25:01PM +0200, Vitaly Kuznetsov wrote:

quoted

Hi,

Commit ccf953d8f3d6 ("fb_defio: Remove custom address_space_operations")
seems to be breaking Hyper-V framebuffer
(drivers/video/fbdev/hyperv_fb.c) driver for me: Hyper-V guest boots
well and plymouth even works but when I try starting Gnome, virtual
screen just goes black. Reverting the above mentioned commit on top of
5.13-rc4 saves the day. The behavior is 100% reproducible. I'm using
Gen2 guest runing on Hyper-V 2019. It was also reported that Gen1 guests
are equally broken.

Is this something known?

I've heard a similar report from Vineeth but we didn't get to the bottom
of this.

I have just tried reverting the commit mentioned above and it solves the 
GUI freeze
I was also seeing. Previously, login screen was just freezing, but VM 
was accessible
through ssh. With the above commit reverted, I can login to Gnome.

Looks like I am also experiencing the same bug mentioned here.

Thanks,
Vineeth