Bug#1151665: mutter: gnome-shell segfaults with NVIDIA 550 after upgrade to 51.0-3

[Simon McVittie]

Control: forwarded -1 https://gitlab.gnome.org/GNOME/mutter/-/work_items/5074

On Thu, 22 Oct 2026 at 20:59:30 +0200, Claudio Giordano wrote:
>Upstream mutter 51 removed support for
>legacy NVIDIA drivers (NEWS 51.alpha, MR !5079); whether 550 counts as
>legacy is unclear

I don't think it necessarily does. 
<https://gitlab.gnome.org/GNOME/mutter/-/work_items/4279> mentions that 
EGLStream (the legacy mechanism that was removed) was needed for the 
v470 driver, but no longer necessary for newer drivers.

(The NVIDIA proprietary driver in Debian is known to be out of date, 
<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1081302> etc., but 
that isn't necessarily the issue here.)

Another possible root cause is that if your laptop combines an NVIDIA 
discrete GPU with an Intel or AMD integrated GPU, and there are 
power-management or hybrid-graphics workarounds in use to force GNOME 
Shell to render on the less-power-consuming integrated GPU, this is 
known to result in a similar crash: 
https://gitlab.gnome.org/GNOME/mutter/-/work_items/5074

>but mutter should not segfault when renderer/EGL
>initialization fails

I think this might be the same crash as 
https://gitlab.gnome.org/GNOME/mutter/-/work_items/5074, happening for 
either the same reason or a different reason. If so, it has a potential 
fix proposed upstream, although the code is not quite right yet 
<https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/5355>.

Please could you get a backtrace from the crash? See: 
https://wiki.debian.org/HowToGetABacktrace

>2. adding a versioned Breaks/Conflicts against nvidia-driver (<< 555) so
>   apt cannot install the broken combination

Can you confirm that the version 555 driver (in experimental) does work? 
Adding this Breaks/Replaces would only be useful if it does actually 
exclude the drivers that don't work.

>3. fixing the NULL dereference so an EGL failure degrades gracefully
>   instead of killing gnome-shell

This is <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/5355> 
upstream.

     smcv