Kernel 6.8.0-39 is in Ubuntu 24.04 repos and does not contain this bug.
Installing and pointing GRUB to it can be another temporary fix.


I found an interesting thread in the Proxmox forum (
https://forum.proxmox.com/threads/ttm-buffer-eviction-failed.152720 )
that contains the following sentence:

"...the bug was introduced in the upstream linux kernel over 3 years ago
through simplification of the kvm/qemu QXL guest video driver and has
propagated from there. The bug was removed briefly by reverting the
prior change (via the upstream linux kernel, but pulled into the kernel
of many distros, e.g. 6.8.0-38 and -39 in Ubuntu and derivatives) before
being re-introduced because the developer said the reverted,
unsimplified code caused crashes in their testing environments..."

Thus:
- versions 6.8.0-38 and -39 in Ubuntu and derivatives do not contain the bug
- what the developer said when he knowingly reintroduced the bug explains well 
why the fix is ​​so long overdue and why it will not likely materialize anytime 
soon


As explained in my first post here, I have an Ubuntu 24.04 VPS server under 
Openstack with this bug, cannot switch to Virtio, neither can increase the 
VRAM, because my VPS provider does not allow me to do so.

So I tried the following:

0- took a snapshot of my VPS, just in case

1- installed kernel 6.8.0-39, which is compatible with Ubuntu 24.04:

    apt-get install linux-image-6.8.0-39-generic

2- marked this kernel as 'hold':

    apt-mark hold linux-image-6.8.0-39-generic

3- changed GRUB conf file to point by default to this kernel:
    nano /etc/default/grub; edited the GRUB_DEFAULT=... line as follows
    (in my server, it could be different in yours; check the 'menuentry' and 
'submenu' lines in your /boot/grub/grub.cfg to find out):
    commented the current GRUB_DEFAULT line, and added:

    GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux
6.8.0-39-generic"

    saved

4- updated GRUB:

    update-grub

5- rebooted

6- checked:

    uname -r

    expected output: 6.8.0-39-generic

Since then, now for several weeks, I have never received the "Buffer
eviction failed" error, nor have I had malfunctions with the QXL/Spice
console nor any other problems, whereas with other kernels I had to
reboot every couple of days.


Installing a superseded kernel is obviously not a proper solution of our
problem but it could be a useful temporary fix for those who cannot
switch from QXL/Spice to other virtual consoles or go 'headless' or
downgrade to Ubuntu 22.04.

Reverting the temporary fix is straightforward:

1. revert changes in /etc/default/grub
2. update-grub
3. reboot
4. uname -r
(5. apt-mark unhold linux-image-6.8.0-39-generic)

Hope this helps.

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https://bugs.launchpad.net/bugs/2065153

Title:
  [qxl] Ubuntu 24.04 VM guest console freezes after some hours

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