The systemd-oomd-defaults rpm installed on Fedora/CentOS images via
mkosi/mkosi.conf.d/centos-fedora/mkosi.conf ships
/usr/lib/systemd/system/system.slice.d/10-oomd-per-slice-defaults.conf:
[Slice]
ManagedOOMMemoryPressure=kill
ManagedOOMMemoryPressureLimit=80%
https://gitlab.com/redhat/centos-stream/rpms/systemd/-/blob/c10s/10-oomd-per-slice-defaults.conf
In a recent flaky CI run on centos-10, the following sequence was
recorded in test/journal/TEST-55-OOMD-1.journal:
[ 77.740597] systemd-oomd[659]: Memory pressure for /system.slice is 85.03% > 80.00% for > 2s with reclaim activity
[ 77.745326] TEST-55-OOMD.sh[1292]: + journalctl --sync
[ 77.749125] systemd-oomd[659]: Considered 19 cgroups for killing, top candidates were:
[ 77.749128] systemd-oomd[659]: Path: /system.slice/systemd-journald.service
[ 77.749134] systemd-oomd[659]: Current Memory Usage: 55.5M
[ 77.749597] systemd-oomd[659]: oomd attempting to kill 407 with KILL
[ 77.749670] systemd-oomd[659]: Marked /system.slice/systemd-journald.service for killing due to memory pressure for /system.slice being 85.03% > 80.00% for > 2s with reclaim activity
[ 77.752252] systemd[1]: systemd-journald.service: systemd-oomd killed 1 process(es) in this unit.
[ 77.752293] systemd[1]: systemd-journald.service: Changed running -> stop-sigterm
[ 329.922401] systemd[1]: systemd-journald.service: Main process exited, code=killed, status=9/KILL
PID 1292 (the test script) never logged anything after the
`journalctl --sync` line at [77.745326], and the unit stayed in
stop-sigterm until [329.922401].
Override /system.slice to ManagedOOMMemoryPressure=auto in the test
setup so the test does not rely on whichever per-slice oomd defaults
the distro happens to ship.
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
System and Service Manager
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