[Regression] Rapid LayerSurface updates can crash libwayland in 1.21.0 release
Following the upgrade to wayland v1.21.0, several users of the Hyprland wlroots compositor have reported regular crashes that seem to be related to rapidly updating layersurfaces, for example quickly toggling an eww bar on/off or receiving a sudden influx of dunst notifications. A coredump of Hyprland seems to point to a libwayland crash.
Downgrading the wayland package on Arch Linux to v1.20.0-2 resolves the issue, which suggests that this may be a regression in the most recent wayland release. Crashes are confirmed both with the main extra/wayland package, as well as the wayland-git AUR package. I have been able to reliably trigger the crash in Hyprland via the following bash command, which causes dunst notifications to rapidly open and close, and crashes libwayland within a second under Hyprland:
while pgrep Hyprland; do notify-send hi && dunstctl close-all; done
I will admit that I have been unable to recreate this crash under other compositors like sway, river, or wayfire.
Vaxerski (the lead developer for Hyprland) has not been able to recreate the crashes on his system, so I am taking the lead on this to the best of my ability. Vaxerski will be following this thread as well to assist with technical details, as I am not a developer, but since I am one of the more involved users affected by the crashes I will be best equipped to troubleshoot and provide crash logs.