Public bug reported: Description: - When using GNOME with fractional scaling enabled via the scale-monitor-framebuffer experimental feature, mutter repeatedly logs the following assertion failure:
gnome-shell[2095]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed - This occurs reliably when launching slow-starting applications (Firefox, Shortwave, others). It is always preceded by: gnome-shell[2095]: Can't update stage views actor unnamed [ClutterActor] is on because it needs an allocation. - Usually gnome-shell survives the assertion, but on at least one occasion it caused a complete session crash, killing all applications and logging out the user. Hardware: iMac 17,1 (Late 2015) AMD Radeon HD 7800 Series (radeonsi, pitcairn) Three displays: internal 5K display at 150% scaling, two external monitors at 100% Software: Linux Mint 22.2 (Ubuntu 24.04 noble base) gnome-shell 46.0-0ubuntu6~24.04.13 libmutter-14-0 46.2-1ubuntu0.24.04.14 mutter-common 46.2-1ubuntu0.24.04.14 gnome-shell-extension-desktop-icons-ng 46+really47.0.9-1ubuntu5 (installed as per LP: #1976204) Experimental features enabled: ['scale-monitor-framebuffer'] Reproducer: Enable fractional scaling (scale-monitor-framebuffer) with a mixed scaling setup (one display at 150%, others at 100%) Launch a slow-starting application such as Firefox or Shortwave Observe assertion in journal: journalctl -f | grep stack_position Journal sequence at time of assertion: Mar 31 10:07:23 gnome-shell[2095]: Can't update stage views actor unnamed [ClutterActor] is on because it needs an allocation. Mar 31 10:07:23 gnome-shell[2095]: Can't update stage views actor unnamed [ClutterActor] is on because it needs an allocation. Mar 31 10:07:23 gnome-shell[2095]: Can't update stage views actor unnamed [ClutterActor] is on because it needs an allocation. Mar 31 10:07:25 systemd[1883]: Started app-gnome-firefox-8650.scope - Application launched by gnome-shell. Mar 31 10:07:26 gnome-shell[2095]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed Journal sequence at time of full session crash: Mar 30 18:55:48 gnome-shell[1978]: Can't update stage views actor unnamed [ClutterActor] is on because it needs an allocation. Mar 30 18:55:49 dbus-daemon[1801]: Activating service name='de.haeckerfelix.Shortwave' Mar 30 18:55:50 gnome-shell[1978]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed Mar 30 18:56:51 systemd[1773]: [email protected]: Main process exited, code=killed, status=9/KILL Notes: - The assertion fires multiple times per session but usually does not crash - On the occasion of the crash, gnome-shell continued for approximately 61 seconds after the assertion before dying - workaround MUTTER_DEBUG_KMS_THREAD_TYPE=user does not prevent the assertion - Installing gnome-shell-extension-desktop-icons-ng (fix for LP: #1976204) did not prevent the assertion but may have improved crash survival - No GNOME Shell extensions were installed prior to installing DING as a workaround attempt - The bug does not reproduce under GNOME on Xorg (gnome-xorg session) - Related upstream issue area: window stack position not initialized before compositor attempts to place window during slow application startup under fractional scaling - Perhaps related to #1976204 ** Affects: mutter (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2146944 Title: meta_window_set_stack_position_no_sync assertion failure and session crash under fractional scaling (scale-monitor-framebuffer) when launching applications To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2146944/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
