linux-kernel - Re: [PATCH -next] cpuset: treate root invalid trialcs as exclusive

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Message-ID: <a46cd51e-e447-40f5-b2de-3067049ce491@huaweicloud.com>
Date: Mon, 17 Nov 2025 15:30:37 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: Sun Shaojie <sunshaojie@...inos.cn>
Cc: cgroups@...r.kernel.org, hannes@...xchg.org,
 linux-kernel@...r.kernel.org, longman@...hat.com, mkoutny@...e.com,
 tj@...nel.org
Subject: Re: [PATCH -next] cpuset: treate root invalid trialcs as exclusive



On 2025/11/17 14:53, Sun Shaojie wrote:
> On 2025/11/15 14:23, Chen Ridong wrote:
>> On 2025/11/17 12:35, Sun Shaojie wrote:
>>> Hi, Ridong,
>>>
>>> Maybe, this patch does not apply to the following cases:
>>>  Step
>>>  #1> echo "root" > A1/cpuset.cpus.partition
>>>  #1> echo "0-1" > B1/cpuset.cpus
>>>  #2> echo "1-2" > A1/cpuset.cpus.exclusive  -> return error
>>>  It should return success here.
>>>
>>> Please consider the following modification.
>>>
>>
>> If A1 will automatically change to a valid partition, I think it should return error.
> 
> Hi, Ridong,
> 
> A1 will not automatically change to a valid partition.
> 
> Perhaps this example is more intuitive.
> 
> For example:
> 
>  Before apply this patch:
>  #1> echo "0-1" > B1/cpuset.cpus
>  #2> echo "root" > A1/cpuset.cpus.partition -> A1's prstate is "root invalid"
>  #3> echo "1-2" > A1/cpuset.cpus.exclusive
>  Return success, and A1's prstate is "root invalid"
> 

I did not apply your patch to test my patch. here are the results I obtained:

	# cd /sys/fs/cgroup/
	# mkdir A1
	# mkdir B1
	# echo 0-1 > B1/cpuset.cpus
	# echo root > A1/cpuset.cpus.partition
	# cat A1/cpuset.cpus.partition
	root invalid (cpuset.cpus and cpuset.cpus.exclusive are empty)
	# echo 1-2 > A1/cpuset.cpus
	# cat A1/cpuset.cpus.partition
	root

This differs from the results you provided.

Never mind, let's focus on whether the rule should be relaxed in your patch. Once that's resolved, I
can resubmit my patch. Let's set this patch aside for now.

Thanks.

-- 
Best regards,
Ridong