"Xorg invoked oom-killer" while resizing terminal windows

qubist · July 28, 2022, 2:27pm

Hi,

On my Linux systems I like to have shortcuts for tiling and maximizing my windows. In Qubes OS I did the same. In XFCE Window Manager settings I set them like:

Tile window to the top: Super+Home
Tile window to the bottom: Super+End
Tile window to the left: Super+Left
Maximize window: Super+Up
…

However, I notice this buggy behavior in Qubes OS:

If I open a XFCE terminal (or xterm) of a qube (e.g. sys-net, sys-usb, sys-whonix) and resize it many times quickly (e.g. by pressing repeatedly or holding Super+Up) the window disappears after a few seconds and xterm (or XFCE terminal) cannot be run again unless the qube is rebooted. I notice a similar behavior in ‘personal’ qube too. In it though, the inside of the terminal window becomes unresponsive - I can still resize it, it does not crash, but I cannot do anything inside it (type, click on the menu). In dom0 I don’t experience this problem though.

In Qube Manager I checked the logs of the qubes in which I tested and I see out of memory messages. They are similar to those “Xorg invoked oom-killer” ones shown in:

github.com/QubesOS/qubes-issues

OOMs in dom0 on recent kernels

opened 04:13PM - 05 Sep 17 UTC

closed 02:08PM - 07 Jun 19 UTC

rootkovska

T: bug C: kernel P: critical R: cannot reproduce

#### Qubes OS version (e.g., `R3.2`): In the last weeks I've been experiencin…g frequent Out Of Memory (OOM) killer actions in dom0, likely due to incorrect memory reporting by the dom0 kernel. This results in X in dom0 getting restarted. In order to recover the system, the user must: 1. Log in again (this is easy, since X defaults to the login page after it gets restarted), 2. Open a terminal and manually remove the `/var/run/shm.id` file, 3. Log out and log in again (i.e. restart the X again). (After this all the gui daemons connect back to all the open windows, so no work is lost and One problem is likely some (upstream?) bug in memory reporting, which results on Qubes memory balance (qmemman) incorrectly taking too much memory from dom0, leaving the OOM no other choice than to kill some memory-hungry process (and X is often a good candidate). Another problem (Qubes-related) is the need to manually remove the `shm.id` file and restart the X. This should be done automatically, so that the user could just log in and have all the windows automatically restored (guid connected back).

I also attempted a workaround - I increased the memory of sys-net from the default 400MB to 1600MB but that didn’t fix the issue.

FWIW the system I am testing on has 64 GiB RAM and a 4K desktop.

For comparison:

On a very old laptop with 2 GiB of RAM running openSUSE and XFCE on a 2K screen there is no such issue. I can hold e.g. Super+Up forever and it does not cause problems.

How can this be fixed, please?

brendanhoar · July 28, 2022, 2:30pm

This smells like more grant tables issues.

B

qubist · July 28, 2022, 5:37pm

What does this mean and what can I do?

brendanhoar · July 28, 2022, 6:47pm

Grants are a Xen mechanism for VMs (including dom0<->domU) to share memory or move data between each other.

With 4.1 much of the inter-VM data transfer, including the UI, is more dependent on grants than in the past.

I’ve seen a lot of Issues in the Qubes-issues Repository traced back to bugs in Xen and/or Qubes usage of grants post R4.0 Qubes release.

Some of these issues are still open in the tracker.

4K displays has long been a trigger.

That being said it could also have to do with video ram settings issues which would be a separate issue.

See here: GUI configuration | Qubes OS

B

qubist · July 29, 2022, 12:30pm

Thanks for this info.

I understand these formulas are for 8-bit displays.

Can you tell me how to modify these formulas for the case of using 10 bit display?

For example, suppose a setup consisting of a 4K 10-bit display and a secondary unpluggable 8-bit 2K display.

qubist · August 2, 2022, 5:46pm

@brendanhoar

Looking again at that guide you give I reread “By default, it is as much as needed for the current display and an additional full HD (FHD) display (1920×1080 8 bit/channel RGBA)”. Testing in 1920x1080 mode though I still experience the issue. I don’t know why, I can only speculate that it might be due to the 10-bit video signal between the computer and the monitor.

I hope you or someone else can answer my previous question, considering the clarification.

qubist · August 6, 2022, 4:00pm

So, after searching for the answer (and not finding it anywhere on the web), I tried to figure it out for myself:

The documentation says:

“By default, it is as much as needed for the current display and an additional full HD (FHD) display (1920×1080 8 bit/channel RGBA).”

and gives the formula:

qvm-features dom0 gui-videoram-min $(($WIDTH * $HEIGHT * 4 / 1024))

I know that “A” in RGBA stands for alpha (transparency) but I have no idea how a video signal can be transparent. Anyway, I assumed that “4” in the formula stands for 4 bytes (8 bits for each of the RGBA channels). So, knowing that 10 is 25% more than 8, I simply added the multiplier 1.25 in the formula for a single 4K 10-bit screen:

(3840 * 2160 * 4 * 1.25) / 1024 = 40500

Then:

qvm-features dom0 gui-videoram-min 40500

and rebooted the computer in order to restart all qubes.

Result: the issue remains.

I even tried not to reboot the whole system, supposing that the change might have not persisted (I have no idea how to check) and repeated the command in dom0. Then I simply restarted sys-net (and the qubes which depend on it).

Result: the issue remains.

I hope someone can help.

qubist · August 8, 2022, 5:50pm

As this is really annoying (and looks buggy) I even tried doubling gui-videoram-min and set it to 81000 (2*40500). Unfortunately, the issue remains. This doc doesn’t seem to solve the problem at all.

I wonder what others’ experience with this is and how it can be solved.

qubist · August 15, 2022, 5:14pm

It’s been quite some time with no feedback.
Is it a because it is a difficult undocumented question? Or maybe I should file a bug report?