linux-kernel - Re: [patch V4 05/20] sched/mmcid: Move scheduler code out of global header

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Message-ID: <aR3tir7yIyHOFLk8@yury>
Date: Wed, 19 Nov 2025 11:17:21 -0500
From: Yury Norov <yury.norov@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Gabriele Monaco <gmonaco@...hat.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Michael Jeanson <mjeanson@...icios.com>,
	Jens Axboe <axboe@...nel.dk>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	"Gautham R. Shenoy" <gautham.shenoy@....com>,
	Florian Weimer <fweimer@...hat.com>,
	Tim Chen <tim.c.chen@...el.com>,
	Shrikanth Hegde <sshegde@...ux.ibm.com>
Subject: Re: [patch V4 05/20] sched/mmcid: Move scheduler code out of global
 header

On Sun, Nov 16, 2025 at 09:48:43PM +0100, Thomas Gleixner wrote:
> This is only used in the scheduler core code, so there is no point to have
> it in a global header.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>

Thanks for unloading global headers!

Acked-by: Yury Norov (NVIDIA) <yury.norov@...il.com>

> ---
>  include/linux/mm_types.h |   13 -------------
>  kernel/sched/core.c      |   20 ++++++++++++++++++--
>  2 files changed, 18 insertions(+), 15 deletions(-)
> 
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -1387,27 +1387,14 @@ static inline unsigned int mm_cid_size(v
>  	return 2 * cpumask_size();	/* mm_cpus_allowed(), mm_cidmask(). */
>  }
>  
> -static inline void mm_set_cpus_allowed(struct mm_struct *mm, const struct cpumask *cpumask)
> -{
> -	struct cpumask *mm_allowed = mm_cpus_allowed(mm);
> -
> -	if (!mm)
> -		return;
> -	/* The mm_cpus_allowed is the union of each thread allowed CPUs masks. */
> -	guard(raw_spinlock)(&mm->mm_cid.lock);
> -	cpumask_or(mm_allowed, mm_allowed, cpumask);
> -	WRITE_ONCE(mm->mm_cid.nr_cpus_allowed, cpumask_weight(mm_allowed));
> -}
>  #else /* CONFIG_SCHED_MM_CID */
>  static inline void mm_init_cid(struct mm_struct *mm, struct task_struct *p) { }
>  static inline int mm_alloc_cid(struct mm_struct *mm, struct task_struct *p) { return 0; }
>  static inline void mm_destroy_cid(struct mm_struct *mm) { }
> -
>  static inline unsigned int mm_cid_size(void)
>  {
>  	return 0;
>  }
> -static inline void mm_set_cpus_allowed(struct mm_struct *mm, const struct cpumask *cpumask) { }
>  #endif /* CONFIG_SCHED_MM_CID */
>  
>  struct mmu_gather;
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2669,6 +2669,8 @@ int push_cpu_stop(void *arg)
>  	return 0;
>  }
>  
> +static inline void mm_update_cpus_allowed(struct mm_struct *mm, const cpumask_t *affmask);
> +
>  /*
>   * sched_class::set_cpus_allowed must do the below, but is not required to
>   * actually call this function.
> @@ -2728,7 +2730,7 @@ static void
>  		put_prev_task(rq, p);
>  
>  	p->sched_class->set_cpus_allowed(p, ctx);
> -	mm_set_cpus_allowed(p->mm, ctx->new_mask);
> +	mm_update_cpus_allowed(p->mm, ctx->new_mask);
>  
>  	if (queued)
>  		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
> @@ -10372,6 +10374,18 @@ void call_trace_sched_update_nr_running(
>   * When a task exits, the MM CID held by the task is not longer required as
>   * the task cannot return to user space.
>   */
> +static inline void mm_update_cpus_allowed(struct mm_struct *mm, const struct cpumask *affmsk)
> +{
> +	struct cpumask *mm_allowed = mm_cpus_allowed(mm);
> +
> +	if (!mm)
> +		return;
> +	/* The mm_cpus_allowed is the union of each thread allowed CPUs masks. */
> +	guard(raw_spinlock)(&mm->mm_cid.lock);
> +	cpumask_or(mm_allowed, mm_allowed, affmsk);
> +	WRITE_ONCE(mm->mm_cid.nr_cpus_allowed, cpumask_weight(mm_allowed));
> +}
> +
>  void sched_mm_cid_exit_signals(struct task_struct *t)
>  {
>  	struct mm_struct *mm = t->mm;
> @@ -10411,7 +10425,9 @@ void sched_mm_cid_fork(struct task_struc
>  	WARN_ON_ONCE(!t->mm || t->mm_cid.cid != MM_CID_UNSET);
>  	t->mm_cid.active = 1;
>  }
> -#endif /* CONFIG_SCHED_MM_CID */
> +#else /* CONFIG_SCHED_MM_CID */
> +static inline void mm_update_cpus_allowed(struct mm_struct *mm, const struct cpumask *affmsk) { }
> +#endif /* !CONFIG_SCHED_MM_CID */
>  
>  #ifdef CONFIG_SCHED_CLASS_EXT
>  void sched_deq_and_put_task(struct task_struct *p, int queue_flags,