On Sat, 16 Jan 2016, Mike Galbraith wrote:
> On Thu, 2016-01-14 at 17:05 +0100, Mike Galbraith wrote:
>
> > This is virgin -rt1 modulo fixlet applied to v4.4.0, built with the
> > .config from v4.4.0 that built it (modulo RT_FULL) rebuilding itself
> > via make -j8.
> >
> > homer:/root # vmstat 10
> > procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
> > r b swpd free buff cache si so bi bo in cs us sy id wa st
> > 0 1 0 14742988 179832 680792 0 0 634 25 326 1196 2 1 89 8 0
> > 8 0 0 14476084 179848 701632 0 0 814 525 2421 12314 11 1 87 1 0
> > 8 0 0 14483232 179864 712656 0 0 165 1628 2404 12320 11 1 87 1 0
> > 8 0 0 14493336 180008 727836 0 0 141 762 2328 11306 11 1 87 0 0
> > 8 0 0 14456436 180024 738356 0 0 159 1478 2336 11939 11 1 87 0 0
> >
> > Way too idle, taking forever.
>
> It now being the weekend...
>
> sched: Disable default set_cpus_allowed() method during update_migrate_disable().
>
> update_migrate_disable() calls class::set_cpus_allowed(), when that method
> is set_cpus_allowed_common(), writing to ->cpus_allowed defeats the intent
> of migrate_disable(), permanently disabling migration instead.
Ha, you found it as well :)
> Signed-off-by: Mike Galbraith <umgwanakikbuti@xxxxxxxxx>
> ---
> kernel/sched/core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1205,6 +1205,8 @@ static int migration_cpu_stop(void *data
> */
> void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
> {
> + if (__migrate_disabled(p))
> + return;
> cpumask_copy(&p->cpus_allowed, new_mask);
> p->nr_cpus_allowed = cpumask_weight(new_mask);
> }
>
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