I think I’ve been hitting this issue lately running fedora 40, kernel 6.10.12 and plasma 6.2.0. It happens maybe once every few days. Lockscreen is really sluggish, moving the cursor has noticeable lag, basically takes multiple seconds to interact with… anything. Just like everyone else, rebooting the machine clears the problem.
Weirdly, I can switch to a nongraphical tty session and even typing has noticeable lag.
Journalctl full of messages telling me my machine is too slow:
Oct 16 17:51:37 fedora kwin_wayland[2586]: kwin_libinput: Libinput: event6 - Touchpad: client bug: event processing lagging behind by 241ms, your system is too slow
Oct 16 17:51:35 fedora kwin_wayland[2586]: kwin_libinput: Libinput: client bug: timer event6 hold: scheduled expiry is in the past (-69ms), your system is too slow
This is the only thing I can find that might indicate whatever is setting it off:
Oct 16 17:29:28 fedora kernel: amdgpu 0000:c1:00.0: [drm] ERROR dc_dmub_srv_log_diagnostic_data: DMCUB error - collecting diagnostic data
Oct 16 17:29:27 fedora kernel: amdgpu 0000:c1:00.0: [drm] ERROR dc_dmub_srv_log_diagnostic_data: DMCUB error - collecting diagnostic data
Oct 16 17:29:27 fedora kernel: amdgpu 0000:c1:00.0: [drm] ERROR dc_dmub_srv_log_diagnostic_data: DMCUB error - collecting diagnostic data
Oct 16 17:29:27 fedora kernel: amdgpu 0000:c1:00.0: [drm] ERROR dc_dmub_srv_log_diagnostic_data: DMCUB error - collecting diagnostic data
It looks like plasma 6.2.1 hasn’t been pushed out to fedora repos yet, I guess I can wait and see if that makes the problem stop happening.