Interestingly, I'm seeing this bug years later in a qemu-kvm instance with i440fx chipset, qxl graphics, SeaBIOS bios, running the latest Bunsenlabs flavor on top of Debian 11. Bunsenlabs is based on Openbox and uses lightdm and light-locker.
It seems to happen frequently when starting a session, but also can happen later on in the session, possibly due to invocation to lock the screen (which seems to happen irregularly/infrequently, possibly because I'm using a VM and not at the console). The example log entry below was associated with a crash of the desktop environment, although the VM was busy at the time and I haven't ruled out that the crash was related to something else. Example log entry: Feb 17 19:46:34 vibrio kernel: [352462.995091] traps: light-locker[1223914] trap int3 ip:7f2e61ea6ca7 sp:7ffe1f16b0f0 error:0 in libglib-2.0.so.0.6600.8[7f2e61e6a000+88000] Example from a session start: Feb 13 00:23:09 vibrio kernel: [ 50.322781] traps: light-locker[1523] trap int3 ip:7ff84c824ca7 sp:7fff2a3fa7e0 error:0 in libglib-2.0.so.0.6600.8[7ff84c7e8000+88000] Note the hex numbers related to libglib-2.0.so.0 are different.
