Messages in this thread Patch in this message | | | Date | Mon, 28 May 2018 16:49:24 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] sched: Make select_task_rq() require cpu_active() for user tasks |
| |
On Sat, May 26, 2018 at 08:46:47AM -0700, Paul Burton wrote:
> --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1565,7 +1565,8 @@ int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) > * not worry about this generic constraint ] > */ > if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) || > - !cpu_online(cpu))) > + !cpu_online(cpu) || > + (!cpu_active(cpu) && !(p->flags & PF_KTHREAD)))) > cpu = select_fallback_rq(task_cpu(p), p);
That is not quite right.. and I find that the wrong patch:
955dbdf4ce87 ("sched: Allow migrating kthreads into online but inactive CPUs")
got merged over my suggested alternative :-(
http://lkml.kernel.org/r/20170725165821.cejhb7v2s3kecems@hirez.programming.kicks-ass.net
So, lets first fix that, and then your patch becomes something like the below I think.
--- 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;
| |