What were you trying to do that didn't work?

Our customer has installed /etc/systemd/system/user@.service.d/delegate.conf as a drop-in with the intended purpose to override the SystemD template file namely /usr/lib/systemd/system/user@.service.
Post reboot, we can see that the Delegate= property has been modified accordingly.
However /sys/fs/cgroup/cgroup.subtree_control is not updated until a subsequent reload of the SystemD manager configuration (i.e. systemctl daemon-reload).

What is the impact of this issue to you?

Production impacting. However, the customer has a workaround by way of a custom SystemD service to enable each required cgroup controller.

Please provide the package NVR for which the bug is seen:

systemd-239-82.el8_10.5.x86_64

How reproducible is this bug?:

Always.

Steps to reproduce

Create this systemd drop-in:

❯ cat /etc/systemd/system/user@.service.d/delegate.conf
[Service]
Delegate=cpu cpuset memory pids
CPUAccounting=yes
MemoryAccounting=yes
TasksAccounting=yes

The purpose of the above is to override the SystemD template unit file /usr/lib/systemd/system/user@.service.
Reboot.

Post reboot each property is applied yet the specified cgroup controllers are not enabled until the SystemD manager configuration is reloaded. See below.

❯ systemctl show user@$(id -u).service -p Delegate -p DelegateControllers -p CPUAccounting
Delegate=yes
DelegateControllers=cpu cpuset memory pids
CPUAccounting=yes

❯ cat /sys/fs/cgroup/cgroup.subtree_control
memory pids

❯ sudo systemctl daemon-reload

❯ cat /sys/fs/cgroup/cgroup.subtree_control
cpuset cpu memory pids

Expected results

❯ cat /sys/fs/cgroup/cgroup.subtree_control
cpuset cpu memory pids

without running systemctl daemon-reload command.

Actual results

❯ cat /sys/fs/cgroup/cgroup.subtree_control
memory pids