Comment 1 for bug 2060310

Using bpftrace I have been able to see which processes trigger the warning:

$ sudo LD_LIBRARY_PATH=. ./bpftrace -e 'tracepoint:syscalls:sys_enter_exec*{ printf("pid: %d, ppid: %d, comm: %s, args: ", pid, curtask->parent->pid, comm); join(args->argv); }'

pid: 3174, ppid: 1, comm: (snapd), args: /snap/snapd/21589/usr/lib/snapd/snapd
pid: 3180, ppid: 3174, comm: snapd, args: systemctl --version
pid: 3181, ppid: 3174, comm: snapd, args: systemd-detect-virt
pid: 3215, ppid: 3176, comm: snapd, args: systemctl is-enabled snapd.apparmor
pid: 3217, ppid: 3176, comm: snapd, args: udevadm info -e

$ sudo journalctl | grep "but reception only permitted for main PID"
Apr 05 16:02:52 qemuname systemd[1]: snapd.service: Got notification message from PID 3180, but reception only permitted for main PID 3174
Apr 05 16:02:52 qemuname systemd[1]: snapd.service: Got notification message from PID 3181, but reception only permitted for main PID 3174
Apr 05 16:02:52 qemuname systemd[1]: snapd.service: Got notification message from PID 3215, but reception only permitted for main PID 3174
Apr 05 16:02:52 qemuname systemd[1]: snapd.service: Got notification message from PID 3217, but reception only permitted for main PID 3174

It is not clear what notification is being sent by these processes yet.