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

Since version "systemd-239-82.el8_10.8.x86_64", running a command that calls "sched_setscheduler", like "chrt -r 1 ls", will fail with an EPERM:

chrt: failed to set pid 0's policy: Operation not permitted

Stracing the process:

35656 08:05:06.230437 sched_setscheduler(0, SCHED_RR, [1]) = -1 EPERM (Operation not permitted) <0.000026> 

The issue seems to have been introduced by the patches from RHEL-9322.

From the current version where the issue happens:

[root@localhost ~]# grep cpu /proc/self/cgroup 
5:cpuset:/
3:cpu,cpuacct:/user.slice

Previous version (systemd-239-82.el8_10.5.x86_64):

[root@localhost ~]# grep cpu /proc/self/cgroup
7:cpu,cpuacct:/
6:cpuset:/

What is the impact of this issue to you?

Customer reported the inability to use the chrt command.

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

systemd-239-82.el8_10.8.x86_64 / systemd-239-82.el8_10.13.x86_64

How reproducible is this bug?:

Always

Steps to reproduce

1. Update from "systemd-239-82.el8_10.5.x86_64" to "systemd-239-82.el8_10.8.x86_64" or higher.
2. Run a command that uses sched_setscheduler. In this example "chrt -r 1 ls".