From: Vineeth Pillai viremana@linux.microsoft.com Sent: Friday, June 4, 2021 8:47 AM To: Wei Liu wei.liu@kernel.org; vkuznets vkuznets@redhat.com Cc: Matthew Wilcox willy@infradead.org; dri-devel@lists.freedesktop.org; linux-hyperv@vger.kernel.org; linux-fbdev@vger.kernel.org; linux-kernel@vger.kernel.org; Michael Kelley mikelley@microsoft.com; Dexuan Cui decui@microsoft.com Subject: 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:
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
As Matthew mentioned, this is a known issue: https://lwn.net/ml/linux-kernel/YLZEhv0cpZp8uVE3@casper.infradead.org/
Matthew has reverted ccf953d8f3d6: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... so the latest mainline should work now.
Thanks, Dexuan