Public bug reported: # Bug Report Draft
## Suggested Title Wayland desktop flicker/ghost window artifacts with repeated `gbm_surface_lock_front_buffer failed` on Intel i915 dual high-refresh monitors ## Package Primary Apport target: `gnome-shell` Likely related package: `libmutter-18-0` / Mutter native Wayland backend ## Summary On Ubuntu 26.04 LTS GNOME Wayland, desktop windows intermittently flicker or show a misaligned ghost/shadow copy of the active window. The flicker is most visible on the primary Dell AW3420DW display and can be triggered by GNOME Shell UI activity such as clicking the top bar date/time menu, receiving toast notifications, GNOME authentication/polkit modal prompts, or click-holding a window title bar to drag it. The visual artifact does not appear in screenshots. While the issue is occurring, the user journal repeatedly logs: ```text gnome-shell: Failed to query buffer age, got error 3003 gnome-shell: Failed to lock front buffer on /dev/dri/card1: gbm_surface_lock_front_buffer failed ``` ## System - OS: Ubuntu 26.04 LTS (`resolute`) - Session: Wayland (`XDG_SESSION_TYPE=wayland`) - GNOME Shell: `50.1-0ubuntu1` - Mutter packages: `libmutter-18-0 50.1-0ubuntu2.1`, `mutter-common 50.1-0ubuntu2.1` - Kernel: `7.0.0-22-generic` - Mesa: `26.0.3-1ubuntu1` - GPU: Intel Arrow Lake-S integrated graphics, PCI ID `8086:7d67` - Kernel driver: `i915` ## Display Setup - Primary: Dell AW3420DW on `DP-3`, `3440x1440@120` - Secondary: LG ULTRAGEAR on `HDMI-1` - Originally `[email protected]` - Tested at `[email protected]` to match the primary refresh rate - VRR modes are available for the Dell display, but the current tested mode is non-VRR. - GNOME Mutter experimental features are disabled: `org.gnome.mutter experimental-features @as []` ## Reproduction / Triggers The issue is intermittent, but commonly starts or becomes worse after one of: 1. Click the GNOME top bar date/time area. 2. Receive desktop toast notifications. 3. Trigger an Ubuntu/GNOME authentication prompt, such as a polkit password dialog. 4. Click and hold a window title bar as if to drag it. 5. Move or interact with ordinary desktop windows, including terminal windows and other apps. When active, the flicker looks like a translucent or shadow-like copy of the window offset from the real window by roughly an inch. The authentication/polkit overlay is one of the clearest triggers: when the Ubuntu authentication dialog appears and asks for authentication, the screen can flicker heavily. ## Expected Result No flicker or ghost window artifacts during normal GNOME Shell/window interactions. ## Actual Result Windows intermittently flicker or show a misaligned ghost/shadow artifact on the primary monitor. During the artifact, the GNOME Shell journal is flooded with: ```text Failed to query buffer age, got error 3003 Failed to lock front buffer on /dev/dri/card1: gbm_surface_lock_front_buffer failed ``` ## Troubleshooting Already Tried - Disabled Mutter experimental features. - Previous value included `scale-monitor-framebuffer` and `xwayland-native-scaling`. - This significantly reduced the severity at first but did not permanently eliminate the issue. - Turned VRR off. - Helped temporarily, but the flicker returned. - Matched both monitors to roughly 120 Hz. - Dell stayed at `3440x1440@120`. - LG changed from `[email protected]` to `[email protected]`. - Helped temporarily, but the flicker returned. - Disabled the Tiling Shell extension. - The GBM/front-buffer errors continued after disabling it. - Re-enabled Tiling Shell with overlay-heavy features disabled. - Disabled snap assist, active screen edges, blur, and preview animations. - This keeps core tiling enabled while reducing extension-driven compositor overlays. The issue does not currently appear isolated to Tiling Shell. It looks more like Mutter/GNOME Shell's Wayland/native backend or the Intel i915 display path gets into a bad compositor state. GNOME Shell overlay surfaces seem to be especially relevant: top-bar popovers, notifications, and the authentication modal all make the issue easier to reproduce. ## Attachments Prepared - `/home/pgdsadmin/gnome-shell-gbm-front-buffer-flicker.apport` - Preferred upload target; includes `ShellJournal`, package versions, `monitors.xml`, and GNOME settings. - `/home/pgdsadmin/mutter-gbm-front-buffer-flicker.apport` - Additional package metadata bundle for `libmutter-18-0`. - `/tmp/gnome-flicker-user-journal.log` - Extracted user journal lines around the reproduced issue. - `/tmp/mutter-display-state.txt` - Current Mutter display configuration from `org.gnome.Mutter.DisplayConfig.GetCurrentState`. ## Privacy Note The Apport bundle may include monitor serials, local package/config details, extension names, and GNOME settings. It should be reviewed before public upload. ** Affects: gnome-shell (Ubuntu) Importance: Undecided Status: New ** Tags: flicker i915 resolute wayland -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2155412 Title: Wayland desktop flicker with gbm_surface_lock_front_buffer failed on Intel i915 dual high-refresh monitors To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/2155412/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
