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From: Waiman Long <llong@redhat.com>
To: Tejun Heo <tj@kernel.org>, Waiman Long <llong@redhat.com>
Cc: Chen Ridong <chenridong@huaweicloud.com>,
	hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] cgroup/cpuset: remove kernfs active break
Date: Wed, 8 Jan 2025 15:04:39 -0500	[thread overview]
Message-ID: <6fb6d82f-a321-4b29-9fd6-60f7a8758233@redhat.com> (raw)
In-Reply-To: <Z37ZVyx_PI6cHwZ7@slm.duckdns.org>


On 1/8/25 3:00 PM, Tejun Heo wrote:
> Hello,
>
> On Wed, Jan 08, 2025 at 02:50:19PM -0500, Waiman Long wrote:
> ...
>> It is not the strict ordering that I am worrying about. It is all about the
>> possibility of hitting some race conditions.
>>
>> I am thinking of a scenario where a cpuset loses all its CPUs in hotunplug
>> and then restored by adding other CPUs. There is chance that the css will be
>> operated on concurrently by the auto-transfer task and another task moving
>> new task to the css. I am not sure if that will be a problem or not. Anyway,
>> it is very rare that we will be in such a situation.
> Hmm... I might be missing something but cgroup_transfer_tasks() is fully
> synchronized against migrations. I don't see anything dangerous there.
>
> Thanks.

I probably misread some of the code. Then it is not an issue anymore.

Thanks,
Longman


  reply	other threads:[~2025-01-08 20:04 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-06  8:19 Chen Ridong
2025-01-08 16:53 ` Tejun Heo
2025-01-08 19:27   ` Waiman Long
2025-01-08 19:35     ` Tejun Heo
2025-01-08 19:50       ` Waiman Long
2025-01-08 20:00         ` Tejun Heo
2025-01-08 20:04           ` Waiman Long [this message]
2025-01-08 19:20 ` Waiman Long
2025-01-08 19:23 ` Tejun Heo
2025-01-09  1:29   ` Chen Ridong
2025-01-09  1:55     ` Tejun Heo
2025-01-09  2:07       ` Chen Ridong

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