I think your suspicion about the 46.2-1ubuntu0.24.04.13 update (the LP #1971434 / monitor-manager backports) is well founded. Cross-refs: LP #2143073 (same symptoms, and a version bisect there found .12 clean over 20 days while .13/.15 leak), my i915 report LP #2148793, and LP #2156739 where most of the evidence below is accumulating.
Setup: ThinkPad T16 Gen 4, Arrow Lake-U, Ubuntu 24.04, kernel 6.17.0-1028-oem, mutter 46.2-1ubuntu0.24.04.15, GNOME 46 Wayland, clamshell with one external HDMI 4K@60 display. Your "OOM while locked, never during use" pattern matches mine, and I can fill in what happens during the locked period: 1. Locking blanks/DPMS-offs the display ~15s later regardless of idle settings (gsd-power hardcodes this after screensaver activation) — which is why the problem tracks LOCKED time specifically. 2. While the display is in DPMS-off, Mutter (gnome-shell) emits MonitorsChanged in pairs every ~8.5 seconds, continuously, captured with dbus-monitor. gsd-xsettings, gsd-power and xdg-desktop-portal re-query the display config every cycle. 3. Each cycle strands ~2 framebuffer-sized GPU buffers (32 MB each at 4K) inside gnome-shell. On my machine (xe driver) they are visible as exported DMA-BUF fds in /proc/<gnome-shell-pid>/fdinfo (exp_name/size fields): ~12 fds/min, ~0.5 GB/min. In one 45-minute locked period the count grew 12 -> 396 (~12.3 GB) and ended in a global OOM that killed the session. On i915 the same class of leak surfaces as Shmem/ShmemHugePages instead (LP #2148793, LP #2143073) — GPU buffer objects either way, which is why no process RSS ever accounts for the lost memory. 4. The buffers are never freed on wake; only a gnome-shell restart releases them. 5. A live event source during power-save appears necessary to sustain the ~8.5 s loop: e.g. audio streaming over HDMI to the monitor's speakers; in LP #2143073 a monitor with flaky input-autodetect (disconnect/reconnect cycles) plays the same role. If your monitor drops off the bus when it enters power-save (yours reportedly started truly powering off after the .13 update), that itself may generate the repeated connector events. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/2146851 Title: OOM during screen lock after mutter DPMS change To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2146851/+subscriptions -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
