linux-kernel - Re: [PATCH 1/2] sched: Make select_task_rq() require cpu

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Date:   Mon, 28 May 2018 09:10:17 -0700
From:   Paul Burton <paul.burton@...s.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/2] sched: Make select_task_rq() require cpu_active()
 for user tasks

Hi Peter,

On Mon, May 28, 2018 at 05:53:06PM +0200, Peter Zijlstra wrote:
> On Mon, May 28, 2018 at 08:45:16AM -0700, Paul Burton wrote:
> > > --- a/kernel/sched/core.c
> > > +++ b/kernel/sched/core.c
> > > @@ -1562,7 +1562,7 @@ int select_task_rq(struct task_struct *p
> > >  	 *   not worry about this generic constraint ]
> > >  	 */
> > >  	if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
> > > -		     !cpu_online(cpu)))
> > > +		     (is_per_cpu_kthread(p) ? !cpu_online(cpu) : !cpu_active(cpu)))
> > >  		cpu = select_fallback_rq(task_cpu(p), p);
> > >  
> > >  	return cpu;
> > 
> > Yes this looks good to me.
> > 
> > Are you planning to submit your change to introduce
> > is_per_cpu_kthread(), or shall I?
> 
> I've got the lot; I just need to write a better changelog for my old
> (now rebased) patch and make a small note in your patch, but will feed
> them to Ingo when done.

Thanks a bunch!

Paul