A number of tests fail with Assertion Error on Ubuntu 22.04 (which uses cgroups v2 by default), in the HotSpot cgroups code. This occurs in a specific configuration where the host has mixed cgroup configuration similar to:
-------------
cat /proc/self/cgroup
1:freezer:/
0::/user.slice/user-1001.slice/session-85.scope
-------------

(See comments below for setting up such an environment).

Reproducible: always (or almost always)
Tests that fail: a variety of tests in tier1 (details below)
Failure type: Assertion

---------------- sample call stack
Caused by: java.lang.AssertionError
at java.base/jdk.internal.platform.CgroupSubsystemFactory.setCgroupV2Path(CgroupSubsystemFactory.java:226)
at java.base/jdk.internal.platform.CgroupSubsystemFactory.lambda$determineType$1(CgroupSubsystemFactory.java:195)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1921)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596)
at java.base/jdk.internal.platform.CgroupSubsystemFactory.determineType(CgroupSubsystemFactory.java:200)
at java.base/jdk.internal.platform.CgroupSubsystemFactory.create(CgroupSubsystemFactory.java:84)
at java.base/jdk.internal.platform.CgroupMetrics.getInstance(CgroupMetrics.java:177)
at java.base/jdk.internal.platform.SystemMetrics.instance(SystemMetrics.java:29)
at java.base/jdk.internal.platform.Metrics.systemMetrics(Metrics.java:58)
at java.base/jdk.internal.platform.Container.metrics(Container.java:43)
at jdk.management/com.sun.management.internal.OperatingSystemImpl.<init>(OperatingSystemImpl.java:183)
at jdk.management/com.sun.management.internal.PlatformMBeanProviderImpl.getOperatingSystemMXBean(PlatformMBeanProviderImpl.java:280)
...

==========================================
Simple reproducer:

$ cat ManagementFactoryTest.java
public class ManagementFactoryTest {
    public static void main(String args[]) {
        System.out.println(java.lang.management.ManagementFactory.getOperatingSystemMXBean());
    }
}

$ ./jdk/bin/java -esa ManagementFactoryTest.java