Plasma 6 External Display Hard Lockup

[alexyao2015]

Describe the bug

I have plasma6 enabled with Wayland on NixOS 24.05.20241007.1bfbbbe.

The below steps causes a full hard display lockup that requires a hard reboot (press and hold power button). I've observed that the processes continue running in the background (e.g. audio from video continues playing) even while the display, mouse, and keyboard (not even caps/num lock work) are completely frozen. Sysrq commands also do not function in this state.

I have reproduced this on two different laptop models (LG Gram 16Z90S and HP ProBook 455 G9) both on NixOS. I have tried Solus linux with plasma 6.1.5 and do not see this issue either. Additionally, I have upgrade to nix unstable and also continue to see this same issue.

Steps To Reproduce

0. Use wayland. This does not occur in x11.
1. Attach external display to laptop. I am using an HDMI cable.
2. Disable all other displays in kde using "Display Configuration"
3. Unplug HDMI cable from laptop.
4. Plug HDMI cable back in.
5. Attempt to drag an existing window or open a new window and drag it. Specifically dragging the window is what causes the hard lockup.

Expected behavior

No hard lockup/freezing

Additional context

Ref: https://bugs.kde.org/show_bug.cgi?id=494619

Nix config

services.xserver.enable = false;
services.displayManager.sddm.enable = true;
services.desktopManager.plasma6.enable = true;
services.displayManager.defaultSession = "plasma";
services.displayManager.sddm.wayland.enable = true;

Notify maintainers

@K900

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
output here

• system: "x86_64-linux"
• host os: Linux 6.10.14, NixOS, 24.05 (Uakari), 24.05.20241014.c0b1da3
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.18.8
• nixpkgs: /nix/store/wdk3xa0vwx7swjdl1samf1bccvyyzfc1-source

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[K900]

That is very strange. Can you try a newer kernel than 6.10? Can you also try the latest nixos-unstable? That should have Plasma 6.2.1 and Qt 6.8.

[alexyao2015]

Already tried and experienced the same thing on unstable. See the referenced kde issue.

I'll give a newer kernel a try, but I doubt that would be the issue given that Solus Linux with the same 6.10 kernel doesn't have this issue.

I will try a completely clean nix os install next with just kde and see if I can reproduce there.

[alexyao2015]

I am unable to reproduce on a clean install with my same config. Since this now looks like something is wrong with the contents of my home directory and not a packaging issue, I will close this.

[alexyao2015]

Discovered the actual cause of the bug here. I was using the kzones plugin. After turning it off, I no longer experienced this behavior.

[alexyao2015]

@K900 Could you give this a try with the kdePackages.kzones installed from nix unstable? I am able to reproduce it on wayland with the extension installed.

[K900]

If this only happens with a specific script, it should probably be reported to that script's upstream.

[alexyao2015]

Hmm okay I've already reported it here gerritdevriese/kzones#109