linux-kernel - Re: [PATCH -next RFC 06/16] cpuset: introduce local_partition

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Message-ID: <63411cc0-5879-4e9c-a7ba-3e8fac362629@huaweicloud.com>
Date: Mon, 20 Oct 2025 16:06:17 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: Waiman Long <llong@...hat.com>, tj@...nel.org, hannes@...xchg.org,
 mkoutny@...e.com
Cc: cgups@...r.kernel.org, linux-kernel@...r.kernel.org,
 lujialin4@...wei.com, chenridong@...wei.com
Subject: Re: [PATCH -next RFC 06/16] cpuset: introduce
 local_partition_enable()



On 2025/10/20 10:44, Waiman Long wrote:
> On 9/28/25 3:12 AM, Chen Ridong wrote:
>> From: Chen Ridong <chenridong@...wei.com>
>>
>> The partition_enable() function introduced in the previous patch can be
>> reused to enable local partitions.
>>
>> First, partition_enable() was enhanced to support local partition enabling
>> by properly handling parent's nr_subparts counter and adding notification
>> operations.
>>
>> Then, the local_partition_enable() function is introduced, which factors
>> out the local partition enablement logic from
>> update_parent_effective_cpumask(). After passing local partition validation
>> checks, it delegates to partition_enable() to complete the partition setup.
>>
>> This refactoring creates a clear separation between local and remote
>> partition operations while maintaining code reuse through the shared
>> partition_enable() infrastructure.
>>
>> Signed-off-by: Chen Ridong <chenridong@...wei.com>
>> ---
>>   kernel/cgroup/cpuset.c | 111 +++++++++++++++++++++++++++--------------
>>   1 file changed, 74 insertions(+), 37 deletions(-)
>>
>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
>> index 0e2f95daf459..154992cdfe9a 100644
>> --- a/kernel/cgroup/cpuset.c
>> +++ b/kernel/cgroup/cpuset.c
>> @@ -1539,6 +1539,7 @@ static void partition_enable(struct cpuset *cs, struct cpuset *parent,
>>                    int new_prs, struct cpumask *new_excpus)
>>   {
>>       bool isolcpus_updated;
>> +    int old_prs;
>>         lockdep_assert_held(&cpuset_mutex);
>>       WARN_ON_ONCE(new_prs <= 0);
>> @@ -1547,15 +1548,21 @@ static void partition_enable(struct cpuset *cs, struct cpuset *parent,
>>       if (cs->partition_root_state == new_prs)
>>           return;
>>   +    old_prs = cs->partition_root_state;
>>       spin_lock_irq(&callback_lock);
>>       /* enable partition should only add exclusive cpus */
>>       isolcpus_updated = partition_xcpus_add(new_prs, parent, new_excpus);
>> -    list_add(&cs->remote_sibling, &remote_children);
>> +    /* enable remote partition */
>> +    if (!parent)
>> +        list_add(&cs->remote_sibling, &remote_children);
>> +    else if (!is_partition_valid(cs))
>> +        parent->nr_subparts += 1;
>>       cpumask_copy(cs->effective_xcpus, new_excpus);
>>       partition_state_update(cs, new_prs, PERR_NONE);
>>       spin_unlock_irq(&callback_lock);
>>       update_unbound_workqueue_cpumask(isolcpus_updated);
>>       cpuset_force_rebuild();
>> +    notify_partition_change(cs, old_prs);
>>   }
> 
> As commented in an earlier patch, the partition_enable() chnage should be moved there.
> 
> Cheers,
> Longman

Thank you, will update.

-- 
Best regards,
Ridong