On Fri, Jun 04, 2021 at 06:37:49PM +0000, Dexuan Cui wrote:

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From: Dexuan Cui
Sent: Friday, June 4, 2021 11:17 AM

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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/?id=
0b78f8bcf4951af30b0ae83ea4fad27d641ab617
so the latest mainline should work now.

Thanks,
Dexuan

Hi Matthew,
With today's latest mainline 16f0596fc1d78a1f3ae4628cff962bb297dc908c,
the Xorg works again in Linux VM on Hyper-V, but when I reboot the VM, I
always see a lot of "BUG: Bad page state in process Xorg " warnings (there
are about 60 such warnings) before the VM reboots.

BTW, I happen to have an older Mar-28 mainline kernel (36a14638f7c0654),
which has the same warnings. 

Any idea which change introduced the warnings? 

Looks like someone forgot to call fb_deferred_io_cleanup()?