[Bug 2075104] Re: user session is randomly terminated by systemd-oom when the system is left alone for a while

[Jurgen Schellaert]

systemctl cat -- user@$(id -u).service:

# /usr/lib/systemd/system/user at .service
#  SPDX-License-Identifier: LGPL-2.1-or-later
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=User Manager for UID %i
Documentation=man:user at .service(5)
After=user-runtime-dir@%i.service dbus.service systemd-oomd.service
Requires=user-runtime-dir@%i.service
IgnoreOnIsolate=yes

[Service]
User=%i
PAMName=systemd-user
Type=notify-reload
ExecStart=/usr/lib/systemd/systemd --user
Slice=user-%i.slice
KillMode=mixed
Delegate=pids memory cpu
DelegateSubgroup=init.scope
TasksMax=infinity
TimeoutStopSec=120s
KeyringMode=inherit
OOMScoreAdjust=100
MemoryPressureWatch=skip

# /usr/lib/systemd/system/user at .service.d/10-login-barrier.conf
#  SPDX-License-Identifier: LGPL-2.1-or-later
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
# Make sure user instances are started after logins are allowed. However this
# is not desirable for user at 0.service since root should be able to log in
# earlier during the boot process especially if something goes wrong.
After=systemd-user-sessions.service

# /usr/lib/systemd/system/user at .service.d/10-oomd-user-service-defaults.conf
[Service]
ManagedOOMMemoryPressure=kill
ManagedOOMMemoryPressureLimit=50%

# /usr/lib/systemd/system/user at .service.d/timeout.conf
# Avoid long hangs during shutdown if user services fail/hang due to X.org
# going away too early
[Service]
TimeoutStopSec=5

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https://bugs.launchpad.net/bugs/2075104

Title:
  user session is randomly terminated by systemd-oom when the system is
  left alone for a while

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  I was surprised last week to find that my computer had logged me out
  when I had left it alone for some 15 minutes.  I did not bother to
  research at the time and did not see any reason as the problem did not
  manifest again .

  Then today, it happens again. The circumstances are similar: I leave
  the system long enough for the screen to power off and come back to
  find myself kicked out of my session. Yes, kicked out, not simply
  locked out. I need  to log in again and find that all running apps and
  open files have all been  closed.

  My journal would appear to show that gnome-shell got stopped as a
  consequence of systemd-oomd killing several applications (see the
  included journalctl snippet - mind that the output is in reverse order
  (journalctl -r)).

  Should not  oomd terminate single applications instead of complete
  user sessions?

  And I do have some doubts about the statistics listed in the journal.
  One of the killed  apps is reported as consuming over 22GB or RAM (out
  of 32). I have been using that app for many years and cannot remember
  having see it use more than a few GB.

  ProblemType: Bug
  DistroRelease: Ubuntu 24.04
  Package: systemd-oomd 255.4-1ubuntu8.2
  ProcVersionSignature: Ubuntu 6.8.0-39.39-generic 6.8.8
  Uname: Linux 6.8.0-39-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.28.1-0ubuntu3
  Architecture: amd64
  CasperMD5CheckResult: pass
  CurrentDesktop: ubuntu:GNOME
  Date: Tue Jul 30 04:00:27 2024
  InstallationDate: Installed on 2022-03-27 (855 days ago)
  InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Alpha amd64 (20220326)
  SourcePackage: systemd
  UpgradeStatus: No upgrade log present (probably fresh install)

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