On Mon, 24 Aug 2020 at 20:31, Xunlei Pang <xlp...@linux.alibaba.com> wrote: > > We've met problems that occasionally tasks with full cpumask > (e.g. by putting it into a cpuset or setting to full affinity) > were migrated to our isolated cpus in production environment. > > After some analysis, we found that it is due to the current > select_idle_smt() not considering the sched_domain mask. > > Fix it by checking the valid domain mask in select_idle_smt(). > > Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings()) > Reported-by: Wetp Zhang <wetp...@linux.alibaba.com> > Signed-off-by: Xunlei Pang <xlp...@linux.alibaba.com> > --- > kernel/sched/fair.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 1a68a05..fa942c4 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6075,7 +6075,7 @@ static int select_idle_core(struct task_struct *p, > struct sched_domain *sd, int > /* > * Scan the local SMT mask for idle CPUs. > */ > -static int select_idle_smt(struct task_struct *p, int target) > +static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, > int target) > { > int cpu; > > @@ -6083,7 +6083,8 @@ static int select_idle_smt(struct task_struct *p, int > target) > return -1; > > for_each_cpu(cpu, cpu_smt_mask(target)) { > - if (!cpumask_test_cpu(cpu, p->cpus_ptr)) > + if (!cpumask_test_cpu(cpu, p->cpus_ptr) || > + !cpumask_test_cpu(cpu, sched_domain_span(sd))) Maybe the following change could be better, :) for_each_cpu_and(cpu, cpu_smt_mask(target), sched_domain_span(sd)) keep a similar style with select_idle_core/cpu, and could reduce loops.
Just an option. Reviewed-by: Jiang Biao <benbji...@tencent.com>