When I ran wildfly testsuite on JDK 17 within a podman container, I got NPE for all tests, please refer to NPE.stacktrace.java below on the stack trace, all work fine if I run it on base metal.
It relates to JDK issue: https://bugs.openjdk.java.net/browse/JDK-8272124, but this demostrates another case when the cgroup path does not start with the mount root.
In this case /proc/self/cgroup
has the following line:
9:memory:/user.slice/user-1000.slice/session-3.scope