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/[email protected]
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;
