Bug#971343: Animated background/wallpaper (changing over time) causes system freeze on Nouveau

[Leandro Cunha]

Em qua., 30 de set. de 2020 às 14:04, Simon McVittie <smcv at debian.org>
escreveu:

> On Wed, 30 Sep 2020 at 12:31:06 -0300, Leandro Cunha wrote:
> > I did this test and there was no crash, but see the attached
> > screenshot to see how the wallpaper.
>
> Hmm, interesting failure mode. I think there was a bug fixed recently
> where the animated background draws one frame at the wrong brightness
> before adjusting correctly to the time of day - this might mean your Shell
> is actually showing half of one frame and half of another or something?
>
>
This made me think that there could be a problem with opengl that may be
occurring in more specific versions of the Kernel. After conducting studies
in other distros and Debian, I realized that the same version of nouveau
was working normally. I have also studied a number of bug reports
associated with other problems that have to do with wallpapers in Gnome.
However, I don't have many details to be able to state this until now, but
I keep studying.

https://www.omgubuntu.co.uk/2015/05/animated-wallpaper-adds-live-backgrounds-to-linux-distros


> > In the bug attached see from 10:29 when I started testing with Kernel
> > 4.19, until 10:44 that appears in the screen capture that shows both
> > wallpapers side by side. Normally the interface stopped responding,
> > but what I do is run su -c "cat /var/log/syslog > log" on tty to
> > check.
>
> To confirm, are you saying that the log entries from Sep 30 10:29 to
> 10:44 are with the 4.19 kernel from Debian 10, but with everything else
> (including Mesa and GNOME) taken from unstable?
>

    Yes.


>
> > What calls attention that the screen is black, but the interface does
> > not freeze with this version of Kernel, being that I ran the tests on
> > Xorg where I had the best performance so far.
>
> This looks interesting:
>
> > Sep 30 10:29:36 debian-pc gnome-shell[1707]: nouveau: kernel rejected
> pushbuf: Não foi possível alocar memória
> > Sep 30 10:29:36 debian-pc kernel: [ 1520.979894] nouveau 0000:01:00.0:
> Xorg[1558]: fail ttm_validate
> > Sep 30 10:29:36 debian-pc kernel: [ 1520.979904] nouveau 0000:01:00.0:
> Xorg[1558]: validating bo list
> > Sep 30 10:29:36 debian-pc kernel: [ 1520.979915] nouveau 0000:01:00.0:
> Xorg[1558]: validate: -12
> > Sep 30 10:29:36 debian-pc gnome-shell[1707]: nouveau: ch7: krec 0 pushes
> 1 bufs 13 relocs 0
>
> This also looks maybe bad:
>
> > Sep 30 10:44:10 debian-pc kernel: [ 2395.486040] nouveau 0000:01:00.0:
> fb: trapped read at 00473a4200 on channel 3 [1fa20000 Xorg[1558]] engine 00
> [PGRAPH] client 0a [TEXTURE] subclient 00 [] reason 00000002
> [PAGE_NOT_PRESENT]
> > Sep 30 10:44:10 debian-pc kernel: [ 2395.493226] nouveau 0000:01:00.0:
> fb: trapped read at 0047913d00 on channel 3 [1fa20000 Xorg[1558]] engine 00
> [PGRAPH] client 0a [TEXTURE] subclient 00 [] reason 00000002
> [PAGE_NOT_PRESENT]
>
> which I think indicates a bug in the nouveau kernel-side driver? But I
> might be wrong.
>
> > Sep 30 10:30:59 debian-pc gnome-shell[1707]: JS ERROR: TypeError:
> this._dialog is null#012_onFocusChanged
> @resource:///org/gnome/shell/ui/closeDialog.js:135:9#012reset
> @resource:///org/gnome/shell/ui/viewSelector.js:452:26#012show
> @resource:///org/gnome/shell/ui/viewSelector.js:275:14#012_animateVisible
> @resource:///org/gnome/shell/ui/overview.js:580:27#012show
> @resource:///org/gnome/shell/ui/overview.js:566:14#012_onShowAppsButtonToggled@
> /usr/share/gnome-shell/extensions/
> dash-to-dock at micxgx.gmail.com/docking.js:1908:31
>
> It's probably best if you disable extensions like dash-to-dock while
> testing this.
>
>     smcv
>

After the release of version 5.9 of Linux, there was a deterioration in
performance, causing frequent crashes with nouveau, which made me stay on
the buster and not use the latest versions of gnome and also of kernel. I
sent a message to a Gnome contributor to help study the bug and I am
waiting for a response from him.
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