Screen completely freezes after some amount of starting GUI
applications and interacting with their windows. A reliable way to
trigger this bug is to run applications with big amount of UI elements.
For example, start Thunderbird and LibreOffice (in this order) at the
same time. It will probaly freeze after an attempt to start
LibreOffice. If not, open a dozen of new documents in LibreOffice, try
to rearrange windows on screen, change virtual desktops several times,
open a web browser... Eventually after all this fuzzing the screen will
freeze.
How it looks like: there are frames of windows on screen with
unrendered internal part. The instead of internal part of these windows
there are often parts of image, which was on screen before freeze. No
reaction on any keyboard interaction, even on trying to change to
virtual terminal with Ctrl-Alt-F1. At the same time, mouse pointer in
most cases still can be moved on screen, but there is no reaction on
pressing mouse buttons.
After some time (5-15 minutes) the computer may unfreeze, but will
freeze again shortly after few attempts to interacts with it.
At the same time, computer remains accessible over SSH and can be
cleanly shut down with ACPI Power-Off button.
Examining syslog showed huge amount of warnings and stack traces from
kernel related to erroneous memory deallocations. See attachment.
Additional details:
- Freezes occure regardless of whether Debian is run as Xen host, or
without Xen.
- Freezes started after upgrading from Buster to Bullseye.
- Blacklisting nouveau in /etc/modprobe.d/ remove freezes. (But for
this workaround I also need to turn on integrated GPU in BIOS and
connect screen to DVI port on motherboard to make X working again.)