I hit the same crash on Ubuntu 26.04 (mutter 50.1-0ubuntu2.5, NVIDIA
595.99.02 open, RTX 3070, no iGPU, Windows mstsc client) and traced it
to a buffer overrun in mutter, not the NVIDIA driver, as Daniel
suspected in comment #9.
The virtual monitor's memfd stream buffer has the size of the virtual
monitor mode, but meta_screen_cast_virtual_stream_src_record_to_buffer()
calls clutter_stage_paint_to_buffer(), which sizes its read-back as
layout x scale. At a fractional scale those differ: mstsc on a 2560x1600
display at 150 % gives a 1707x1067 layout, so mutter reads back
2561x1601 into a 2560x1600 buffer (stride 10240). A diagnostic log line
I added to that function showed this on every frame:
Virtual screen cast: view 1707x1067 @ 1.500 does not match buffer
2560x1600 stride 10240
The backtrace matches yours: the libnvidia-eglcore frames sit under
cogl_framebuffer_read_pixels_into_bitmap() <-
clutter_stage_paint_to_buffer (scale=1.5, stride=10240). Mesa usually
survives the same overrun, which is why forcing Mesa on an iGPU works
around it.
Upstream:
- Issue: https://gitlab.gnome.org/GNOME/mutter/-/work_items/5151
- Fix for 50.x: https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/5251, a
reviewed backport of commit 93a178eaf from main. mutter 51 already contains it.
With !5251 applied to Ubuntu's 50.1 package, Remote Login at
2560x1600/1.5 works for me in both the greeter and the user session,
across reconnects. This looks like the same issue as bug #2156443. Could
the mutter task track the upstream issue, with the nvidia-graphics-
drivers-610 task set to Invalid?
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https://bugs.launchpad.net/bugs/2162030
Title:
gnome-shell crashed with SIGSEGV in libnvidia-eglcore.so.610.43.02
from cogl_framebuffer_read_pixels_into_bitmap()
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