SRU template for the noble backport (debdiff attached to comment #9). Verified locally as described there; I will verify again once a package is in noble-proposed.
[ Impact ] On noble, gnome-shell (user session and GDM greeter) leaks scanout buffers while the displays are in power save whenever a monitor reports hotplug events. mutter detaches the onscreens on every view rebuild, but only frees detached onscreens after a modeset, which never happens while in power save. Some monitors and KVM switches pulse hotplug every few seconds while blanked, so memory (shmem / dma-buf) grows by several framebuffers per pulse until the session or greeter is OOM-killed, the global OOM killer takes other processes, or the panel fails to come back. [ Test Plan ] 1. Use the native backend (Wayland session or the GDM greeter) with a monitor that toggles hotplug while in DPMS off (reproducible by unplugging/replugging the cable, or with a KVM/monitor that pulses HPD in standby). 2. Let the screen blank by waiting for the idle timeout (org.gnome.desktop.session idle-delay; 300 s by default, also on the GDM greeter). 3. While blanked, trigger several hotplug events. 4. Watch the session's shmem, e.g. `grep shmem /sys/fs/cgroup/user.slice/user-$UID.slice/memory.stat`. Expected with the fix: shmem stays flat across hotplugs while blanked, and the displays come back normally on wake. Without the fix: shmem grows by several scanout-sized buffers per hotplug. [ Where problems could occur ] The change affects when detached onscreens are released in the native renderer, and power-save handling in the monitor manager. A mistake could show up as a crash or a use-after-free during hotplug while in power save (the reason upstream needed c145106d on top of af0c9808, so all three commits must be taken together), or as a black screen or missing output when leaving power save after a hotplug. Nothing changes for the X11 backend or outside power save. [ Other Info ] Upstream: https://gitlab.gnome.org/GNOME/mutter/-/issues/4101, MR !5285 (main), !5325 (gnome-50), commits af0c9808, 83c465ff, c145106d, released in mutter 50.5. The noble backport drops the new upstream test case (native-kms-device power-save gamma test) and its META_EXPORT_TEST markers, since 46.x lacks the test helpers. The exported ABI is unchanged. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2167374 Title: gnome-shell leaks scanout dma-bufs while locked (fixed in mutter 50.5) To manage notifications about this bug go to: https://bugs.launchpad.net/mutter/+bug/2167374/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
