cgroup/cpuset: Correctly set isolated_cpus when switching partition state

When update_prstate() is called to switch the partition state from
root to isolated or vice versa, the whole effective_xcpus is passed to
isolated_cpus_update(). However, if there are child partitions present,
some of the effective_xcpus are dedicated to those child partitions
and their partition states will remain the same or get invalidated in
the case of child root partition with isolated parent in the latter
update_cpumasks_hier() call. In the latter case, their exclusive CPUs
will be returned to their parent.

Therefore isolated_cpus may be set incorrectly with child partitions
underneath. Fix that by excluding their exclusive CPUs in computing
the correct cpumask of exclusive CPUs used by that partition alone.

Add new test cases into test_cpuset_prs.sh to test for such cases.

Fixes: 11e5f407b64a ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
Cc: stable@vger.kernel.org # v6.8+
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Ridong Chen <ridong.chen@linux.dev>
Tested-by: Ridong Chen <ridong.chen@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>

0 files changed, 0 insertions, 0 deletions