linux-kernel - Re: [PATCH 21/33] cpuset: Remove cpuset_cpu_is

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Message-ID: <eb7920d4-bca6-4692-9b8f-7feb715a6ec2@redhat.com>
Date: Fri, 26 Dec 2025 15:48:08 -0500
From: Waiman Long <llong@...hat.com>
To: Frederic Weisbecker <frederic@...nel.org>,
 LKML <linux-kernel@...r.kernel.org>
Cc: Michal Koutný <mkoutny@...e.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>,
 Catalin Marinas <catalin.marinas@....com>,
 Chen Ridong <chenridong@...wei.com>, Danilo Krummrich <dakr@...nel.org>,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Gabriele Monaco <gmonaco@...hat.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Ingo Molnar <mingo@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
 Jens Axboe <axboe@...nel.dk>, Johannes Weiner <hannes@...xchg.org>,
 Lai Jiangshan <jiangshanlai@...il.com>,
 Marco Crivellari <marco.crivellari@...e.com>, Michal Hocko
 <mhocko@...e.com>, Muchun Song <muchun.song@...ux.dev>,
 Paolo Abeni <pabeni@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 Phil Auld <pauld@...hat.com>, "Rafael J . Wysocki" <rafael@...nel.org>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 Shakeel Butt <shakeel.butt@...ux.dev>, Simon Horman <horms@...nel.org>,
 Tejun Heo <tj@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Vlastimil Babka <vbabka@...e.cz>, Will Deacon <will@...nel.org>,
 cgroups@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-block@...r.kernel.org, linux-mm@...ck.org, linux-pci@...r.kernel.org,
 netdev@...r.kernel.org
Subject: Re: [PATCH 21/33] cpuset: Remove cpuset_cpu_is_isolated()

On 12/24/25 8:45 AM, Frederic Weisbecker wrote:
> The set of cpuset isolated CPUs is now included in HK_TYPE_DOMAIN
> housekeeping cpumask. There is no usecase left interested in just
> checking what is isolated by cpuset and not by the isolcpus= kernel
> boot parameter.
>
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> ---
>   include/linux/cpuset.h          |  6 ------
>   include/linux/sched/isolation.h |  4 +---
>   kernel/cgroup/cpuset.c          | 12 ------------
>   3 files changed, 1 insertion(+), 21 deletions(-)
>
> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
> index 1c49ffd2ca9b..a4aa2f1767d0 100644
> --- a/include/linux/cpuset.h
> +++ b/include/linux/cpuset.h
> @@ -79,7 +79,6 @@ extern void cpuset_unlock(void);
>   extern void cpuset_cpus_allowed_locked(struct task_struct *p, struct cpumask *mask);
>   extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
>   extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
> -extern bool cpuset_cpu_is_isolated(int cpu);
>   extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
>   #define cpuset_current_mems_allowed (current->mems_allowed)
>   void cpuset_init_current_mems_allowed(void);
> @@ -215,11 +214,6 @@ static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
>   	return false;
>   }
>   
> -static inline bool cpuset_cpu_is_isolated(int cpu)
> -{
> -	return false;
> -}
> -
>   static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
>   {
>   	return node_possible_map;
> diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
> index 6842a1ba4d13..19905adbb705 100644
> --- a/include/linux/sched/isolation.h
> +++ b/include/linux/sched/isolation.h
> @@ -2,7 +2,6 @@
>   #define _LINUX_SCHED_ISOLATION_H
>   
>   #include <linux/cpumask.h>
> -#include <linux/cpuset.h>
>   #include <linux/init.h>
>   #include <linux/tick.h>
>   
> @@ -84,8 +83,7 @@ static inline bool housekeeping_cpu(int cpu, enum hk_type type)
>   static inline bool cpu_is_isolated(int cpu)
>   {
>   	return !housekeeping_test_cpu(cpu, HK_TYPE_DOMAIN) ||
> -	       !housekeeping_test_cpu(cpu, HK_TYPE_TICK) ||
> -	       cpuset_cpu_is_isolated(cpu);
> +	       !housekeeping_test_cpu(cpu, HK_TYPE_TICK);
>   }
>   
>   #endif /* _LINUX_SCHED_ISOLATION_H */
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 25ac6c98113c..cd6119c02beb 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -29,7 +29,6 @@
>   #include <linux/mempolicy.h>
>   #include <linux/mm.h>
>   #include <linux/memory.h>
> -#include <linux/export.h>
>   #include <linux/rcupdate.h>
>   #include <linux/sched.h>
>   #include <linux/sched/deadline.h>
> @@ -1490,17 +1489,6 @@ static void update_isolation_cpumasks(void)
>   	isolated_cpus_updating = false;
>   }
>   
> -/**
> - * cpuset_cpu_is_isolated - Check if the given CPU is isolated
> - * @cpu: the CPU number to be checked
> - * Return: true if CPU is used in an isolated partition, false otherwise
> - */
> -bool cpuset_cpu_is_isolated(int cpu)
> -{
> -	return cpumask_test_cpu(cpu, isolated_cpus);
> -}
> -EXPORT_SYMBOL_GPL(cpuset_cpu_is_isolated);
> -
>   /**
>    * rm_siblings_excl_cpus - Remove exclusive CPUs that are used by sibling cpusets
>    * @parent: Parent cpuset containing all siblings
Reviewed-by: Waiman Long <longman@...hat.com>