Comment 2 for bug 2051352

I was able to reproduce it in the AWS instances for both Focal and Jammy.
In focal, I was able to reproduce the issue up until version 5.4.0-1009-aws, so it's not a regression.
We didn't catch this before because the AppArmor tests only run when the feature is present, which only happened now for mqueue.

To reproduce on earlier kernel versions I ran the following commands
$ sudo apt install dpkg-dev pkg-config libapparmor-dev
$ apt source apparmor
$ cd apparmor-*/tests/regression/apparmor
$ USE_SYSTEM=1 make
$ result=PASS; while [ "$result" == "PASS" ]; do result=""; result=$(sudo ~/apparmor-*/tests/regression/apparmor/posix_mq_rcv -c ~/apparmor-*/tests/regression/apparmor/posix_mq_snd -k /queuename -n mq_notify); done

The last command only returns if we are able to reproduce the issue. It usually reproduces in less than 10 seconds.
Note that the test is running unconfined, so it's unlikely an issue with apparmor.