linux-kernel - Re: [PATCH -next RFC 13/16] cpuset: use partition_disable for compute_partition_effective

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Message-ID: <21d14cb8-3c8f-45cd-abdd-961271d537da@redhat.com>
Date: Sun, 19 Oct 2025 23:02:04 -0400
From: Waiman Long <llong@...hat.com>
To: Chen Ridong <chenridong@...weicloud.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 13/16] cpuset: use partition_disable for
 compute_partition_effective_cpumask


On 9/28/25 3:13 AM, Chen Ridong wrote:
> From: Chen Ridong <chenridong@...wei.com>
>
> Replace the partition invalidation logic in the
> compute_partition_effective_cpumask() with a call to partition_disable().
>
> This centralizes partition state management and ensures consistent
> handling of partition disable operations throughout the cpuset subsystem.
>
> Signed-off-by: Chen Ridong <chenridong@...wei.com>
> ---
>   kernel/cgroup/cpuset.c | 28 +++++++---------------------
>   1 file changed, 7 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 6625b803ba02..20288dbd6ccf 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -170,15 +170,6 @@ static inline bool cs_is_member(const struct cpuset *cs)
>   	return cs->partition_root_state == PRS_MEMBER;
>   }
>   
> -/*
> - * Callers should hold callback_lock to modify partition_root_state.
> - */
> -static inline void make_partition_invalid(struct cpuset *cs)
> -{
> -	if (cs->partition_root_state > 0)
> -		cs->partition_root_state = -cs->partition_root_state;
> -}
> -
>   /*
>    * Send notification event of whenever partition_root_state changes.
>    */
> @@ -2073,6 +2064,7 @@ static void compute_partition_effective_cpumask(struct cpuset *cs,
>   	struct cgroup_subsys_state *css;
>   	struct cpuset *child;
>   	bool populated = partition_is_populated(cs, NULL);
> +	enum prs_errcode prs_err;
>   
>   	/*
>   	 * Check child partition roots to see if they should be
> @@ -2095,26 +2087,20 @@ static void compute_partition_effective_cpumask(struct cpuset *cs,
>   		 * partition root.
>   		 */
>   		WARN_ON_ONCE(is_remote_partition(child));
> -		child->prs_err = 0;
> +		prs_err = 0;
>   		if (!cpumask_subset(child->effective_xcpus,
>   				    cs->effective_xcpus))
> -			child->prs_err = PERR_INVCPUS;
> +			prs_err = PERR_INVCPUS;
>   		else if (populated &&
>   			 cpumask_subset(new_ecpus, child->effective_xcpus))
> -			child->prs_err = PERR_NOCPUS;
> -
> -		if (child->prs_err) {
> -			int old_prs = child->partition_root_state;
> +			prs_err = PERR_NOCPUS;
>   
> +		if (prs_err) {
>   			/*
>   			 * Invalidate child partition
>   			 */
> -			spin_lock_irq(&callback_lock);
> -			make_partition_invalid(child);
> -			cs->nr_subparts--;
> -			child->nr_subparts = 0;
> -			spin_unlock_irq(&callback_lock);
> -			notify_partition_change(child, old_prs);
> +			partition_disable(child, parent_cs(child),

The parent of child should just be cs. You don't need to use parent_cs() 
to get it.

Cheers,
Longman


> +					  -child->partition_root_state, prs_err);
>   			continue;
>   		}
>   		cpumask_andnot(new_ecpus, new_ecpus,