Re: [PATCH v3 6/9] cgroup/cpuset: Add a new isolated cpus.partition type

Hello Waiman.

On Tue, Jul 20, 2021 at 10:18:31AM -0400, Waiman Long longman@redhat.com wrote:

@@ -2026,6 +2036,22 @@ static int update_prstate(struct cpuset *cs, int new_prs) [...]

• } else if (old_prs && new_prs) {

If an isolated root partition becomes invalid (new_prs == PRS_ERROR)...

• /*
  

•  * A change in load balance state only, no change in cpumasks.
  

•  */
  

• update_flag(CS_SCHED_LOAD_BALANCE, cs, (new_prs != PRS_ISOLATED));
  

...this seems to erase information about CS_SCHED_LOAD_BALANCE zeroness.

IOW, if there's an isolated partition that becomes invalid and later valid again (a cpu is (re)added), it will be a normal root partition without the requested isolation, which is IMO undesired.

I may have overlooked something in broader context but it seems to me the invalidity should be saved independently of the root/isolated type.

Regards, Michal