Re: [PATCH] cgroup/cpuset: Properly disable partition when partition state switching fails

[Tejun Heo]

Hello,

On Tue, Sep 29, 2026 at 03:40:27PM +0800, Guopeng Zhang wrote:
> However, after the parent is created, the ownership of full housekeeping
> CPUs can still change, so passing the check at creation time doesn't seem
> to guarantee that returning CPUs later is still safe.

I think any CPU under an isolated partition should count as isolated when
testing whether the system has a housekeeping CPU left, whether child
partitions carved some out or not. Those CPUs go back to the isolated
parent whenever the child partition is disabled or invalidated, so they
can't be counted on for housekeeping. In your example, making C isolated
would then fail.

Thanks.

--
tejun