Full system freeze in specific focus switch situation with Plasma 6

Brief summary of the problem:

When a borderless windowed or fullscreen game with mangohud (have frozen with it hidden as well as visible) gains or loses focus on Plasma 6.0.5+, there is a chance my system will completely freeze.
After the freeze occurs, nothing is written to the journal. TTY cannot be switched. The system also stops responding to SSH.

I went to KDE when I first experienced the issue, but was told to report here. Issue with more details.

Hardware description:

• CPU: R9 5900X
• GPU: PowerColor Red Devil 6700 XT 06:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Navi 22 [Radeon RX 6700/6700 XT/6750 XT / 6800M/6850M XT] [1002:73df] (rev c1)
• System Memory: 32GB DDR4 3600
• Display(s): Asus XG27AQ 2560x1440 144Hz Freesync (Adaptive sync: Automatic), Asus VS239H 1920x1080 60Hz
• Type of Display Connection: Display Port, HDMI>Display Port (active adapter)

System information:

• Distro name and Version: CachyOS
• Kernel version: 6.10.6-3
• Custom kernel: cachyos
• AMD official driver version: N/A

How to reproduce the issue:

Be running KDE Plasma 6.0.5+. I've only experienced the issue while on Wayland as I don't use X11 regularly.
Launch a borderless windowed or fullscreen game with mangohud. So far I've only experienced this with mangohud active, with multiple games on different engines.
Spam the meta key to toggle the application launcher, or spam alt+tab between another window. mangohud will flicker each time the window loses and regains focus.
Eventually, the system may freeze. It seems fairly inconsistent.

As mentioned in the KDE issue, mangohud doesn't flicker when using gamescope. Example: gamescope -f -W 2560 -H 1440 -- gamescope %command%

changed the description

I would suggest turning off vrr and try again for couple of weeks. I had these freezes when doing focus switch and as you describe there was nothing in logs, and I turned off vrr to solve the issue. #3322 #3460 (closed)

I haven't had a chance to game normally with Adaptive sync: Never. But I spent some more time just tabbing back and forth on a borderless fullscreen game. Does look like VRR could be part of it. Still feels like mangohud is part of it for me, but this much might not be enough to say for sure.

No freeze after ~20 minutes tabbing with Adaptive sync: Never and mangohud on.
Froze again within 5 minutes tabbing with Adaptive sync: Automatic and mangohud on.
Still no freeze after ~20 minutes tabbing with Adaptive sync: Automatic and mangohud OFF.

I don't think its related to mangohud. Freezes happens when going to fullscreen in browser or in mpv when vrr is active. I haven't had any freezes in the last 2 month after I disabled vrr.

Tried toggling fullscreen with mpv for 20 minutes with playback on Adaptive sync: Automatic, but wasn't able to get a freeze.

I just don't remember getting these freezes I'm experiencing prior to kwin 6.0.4/.1, which changed some direct scanout stuff.
That had the side effect of introducing the flicker in mangohud when changing focus, which didn't exist up to kwin 6.0.3.1.
kwin 6.0.4 initially had a problem with how it checked for something which caused severe framerate issues in borderless windowed/fullscreen and made mangohud flicker badly without doing anything. And my system would quickly freeze.
Can't remember if I tried without mangohud, but either way borderless windowed/fullscreen was unusable.
kwin 6.0.4.1 fixed that problem, but mangohud flickering when changing focus remained. And I occasionally experienced freezes while tabbing out of borderless windowed/fullscreen games. And I almost always use mangohud.

But then using gamescope seems to work around the issue entirely? Again, no flicker in mangohud and haven't had a freeze when tabbing with games using it since 6.0.4.

But if it is happening with Gnome like with kwin, then I don't know...

Haven't really tried other overlays, but Steam's seems fine.
I guess for now since I've got an MMO I can dual client, I'll try seeing if I freeze tabbing between those windows with Adaptive sync: Automatic and no mangohud.

Well, I just had a freeze with Adaptive sync: Automatic and no mangohud when I tried to alt tab from a borderless windowed game. So I guess that does rule out the mangohud angle.
I still wonder about what that flicker with mangohud might be indicative of. As far as I can remember, my only freezes prior to kwin 6.0.4 were from the hardware encode/decode at the same time issue. Haven't experienced that in quite a while, actually.

And I still haven't been able to force a freeze with fullscreen gamescope while VRR is enabled. According to my monitor's OSD it's still trying to match whatever framerate I limit the game to to. But it looks rough, jumping between around the target to the max refresh. Without gamescope, it's pretty steady on whatever it's limited to.

I haven't had any freezes in a while, and related VRR causing freezing issues have been closed as fixed so I suppose this is resolved.

Seeing the same on Gnome 46 (experimental VRR enabled) and a 7900XTX, kernel 6.9.12 and 6.10.5

added 6000 dGPU Series label

added DC label

mentioned in issue #3460 (closed)

Same experience here, happens when watching fullscreen videos and moving the mouse or changing sound volume.

Disabling adaptive sync seems to fix the issue.

Operating System: EndeavourOS 
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.10.6-zen1-1-zen (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor
Memory: 31,3 GiB of RAM
Graphics Processor: AMD Radeon RX 6700 XT
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: X470 AORUS ULTRA GAMING

closed