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From: Tejun Heo <tj@kernel.org>
To: Guopeng Zhang <guopeng.zhang@linux.dev>,
	Waiman Long <longman@redhat.com>
Cc: "Ridong Chen" <ridong.chen@linux.dev>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Hui Peng" <benquike@gmail.com>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cgroup/cpuset: Properly disable partition when partition state switching fails
Date: Tue, 29 Sep 2026 06:42:49 -1000	[thread overview]
Message-ID: <95e04dc55645c84c033ccca1a1359d84@kernel.org> (raw)
In-Reply-To: <5e658521-1d8f-47bd-87a2-809a79a10186@linux.dev>

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

  parent reply	other threads:[~2026-09-29 16:42 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-28 23:51 Waiman Long
2026-09-29  2:07 ` Tejun Heo
2026-09-29  3:16   ` Waiman Long
2026-09-29  7:40     ` Guopeng Zhang
2026-09-29 15:49       ` Waiman Long
2026-09-29 16:42       ` Tejun Heo [this message]
2026-09-29 18:21         ` Waiman Long

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