linux-kernel - Re: [bug report] Commit ccf953d8f3d6 ("fb_defio: Remove custom address_space

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Message-ID: <20210604130014.tkeozyn4wxdsr6o2@liuwe-devbox-debian-v2>
Date:   Fri, 4 Jun 2021 13:00:14 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        dri-devel@...ts.freedesktop.org, linux-hyperv@...r.kernel.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michael Kelley <mikelley@...rosoft.com>, wei.liu@...nel.org,
        Dexuan Cui <decui@...rosoft.com>, viremana@...ux.microsoft.com
Subject: Re: [bug report] Commit ccf953d8f3d6 ("fb_defio: Remove custom
 address_space_operations") breaks Hyper-V FB driver

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

Wei.

> -- 
> Vitaly
>