On Wed, Apr 03, 2024 at 04:26:38PM +0200, Valentin Schneider vschneid@redhat.com wrote:
Also, I gave Michal's patch a try and it looks like it's introducing a
Thank you.
cgroup_threadgroup_rwsem -> cpuset_mutex ordering from cgroup_transfer_tasks_locked() `\ percpu_down_write(&cgroup_threadgroup_rwsem); cgroup_migrate() `\ cgroup_migrate_execute() `\ ss->can_attach() // cpuset_can_attach() `\ mutex_lock(&cpuset_mutex);
which is invalid, see below.
_This_ should be the right order (cpuset_mutex inside cgroup_threadgroup_rwsem), at least in my mental model. Thus I missed that cpuset_mutex must have been taken somewhere higher up in the hotplug code (CPU 0 in the lockdep dump, I can't easily see where from) :-/.
Michal