Bug 492838 - Pressing CTRL+ALT+F12 crashes the system
Summary: Pressing CTRL+ALT+F12 crashes the system
Status: RESOLVED NOT A BUG
Alias: None
Product: kwin
Classification: Plasma
Component: compositing (show other bugs)
Version: 6.1.4
Platform: Fedora RPMs Linux
: NOR crash
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2024-09-08 19:38 UTC by gggeri91
Modified: 2024-09-19 18:07 UTC (History)
1 user (show)

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Latest Commit:
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Sentry Crash Report:


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Description gggeri91 2024-09-08 19:38:44 UTC
SUMMARY
Pressing CTRL+ALT+F12 freezes the system, the mouse wouldn't move anymore. After some time the system reboots itself.
I just wanted to turn off the compositor to see whether it reduces mouse lag or not in games running with Lutris. Same games doesn't show any lag in Windows, so I just wanted to troubleshoot what causes the mouse lag and turning off the compositor would be the very first thing to try, but I immediately crashed the system.
Please let me know if you need more info along with the commands I should execute to extract the logs/configs you need.

STEPS TO REPRODUCE
1. Start the system and login
2. You're on the desktop
3. just press CTRL+ALT+F12

OBSERVED RESULT
The screen freezes, system is unusable and has to be rebooted. The mouse wouldn't move. All is frozen.

EXPECTED RESULT
Compositor turns off/on (toggle).


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 40 KDE
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0 
Qt Version: 6.7.2

ADDITIONAL INFORMATION
Operating System: Fedora Linux 40
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.10.7-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 62.7 GiB of RAM
Graphics Processor: AMD Radeon RX 6700 XT
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7D52
System Version: 1.0
Comment 1 reports_go_brrr 2024-09-10 18:41:43 UTC
Only tested on Arch, for me Ctrl+Alt+F12 switches to tty12 and Ctrl+Alt+F1 returns to Plasma session. Nothing crashes.

Operating System: Arch Linux 
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.10.7-arch1-1 (64-bit)
Graphics Platform: Wayland
Comment 2 gggeri91 2024-09-11 19:37:23 UTC
(In reply to reports_go_brrr from comment #1)
> Only tested on Arch, for me Ctrl+Alt+F12 switches to tty12 and Ctrl+Alt+F1
> returns to Plasma session. Nothing crashes.
> 
> Operating System: Arch Linux 
> KDE Plasma Version: 6.1.4
> KDE Frameworks Version: 6.5.0
> Qt Version: 6.7.2
> Kernel Version: 6.10.7-arch1-1 (64-bit)
> Graphics Platform: Wayland


Your reply gave me the idea to try something different and indeed the system did not crash, but something else is going on.

I press CTRL+ALT+F12
Result: 
  - I can't move the mouse anymore. 
  - The keyboard still works, but Plasma is not reacting to any key presses (like WIN key to open launcher). 
  - My usb mouse and usb headset disconnects right after this key combination is pressed

a) Pressing CTRL+ALT+DELETE reboots the system.
  - Pressing this key combination shows the Fedora loading screen and the system gracefully shuts down and restarts.

b) Pressing CTRL+ALT+F2 makes everything work again.
Result:
  - My usb mouse and usb headset reconnects right after this key combination is pressed
  - Suddenly everything works again, I can move the mouse and my system is back to normal

The headset and the mouse behavior is the same regardless of what USB port they are plugged in. 

So you are right, it is not a crash. What else should I try to narrow this down to help the diagnosis?
Comment 3 gggeri91 2024-09-11 19:46:28 UTC
Okay, seems like CTRL+ALT+F12 is switching over to TTY, but it is invisible. So I still see the framebuffer from KDE Plasma, and I do not see the TTY.
For example CTRL+ALT+F3 opens up a TTY as it should, I see the terminal on screen in character mode. Same goes for CTRL+ALT+F4.
I can switch back to the graphical user interface by pressing CTRL+ALT+F2.

I guess this ticket can be closed. Seems like there is no keyboard shortcut anymore to toggle the compositor, correct me if I'm wrong.
Comment 4 reports_go_brrr 2024-09-19 18:05:22 UTC
About CTRL+ALT+DELETE
Actually I've got recently with this "Logout" thing. This led my system totally freezed, even TTY display switching didn't help, nor Display ports switching helped. I saw blank screen on second output, totally black, without any ability to change TTY as on first output. Even pressing shutdown button didn't helped although it was responsible for turning off PC. 
I think "Logout" thing is a culprit.

Got this thing on:
Operating System: Arch Linux
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.10.7-arch1-1 (64-bit)
Graphics Platform: Wayland
Comment 5 reports_go_brrr 2024-09-19 18:07:21 UTC
First output wasn't active so my monitor went Idle then. Some "black magic" is going on there 😂