Messages in this thread | | | Date | Mon, 24 Aug 2020 19:08:20 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH] sched/fair: Fix wrong cpu selecting from isolated domain |
| |
* Xunlei Pang <xlpang@linux.alibaba.com> [2020-08-24 20:30:19]:
> 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.zy@linux.alibaba.com> > Signed-off-by: Xunlei Pang <xlpang@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))) > continue;
Don't think this is right thing to do. What if this task had set a cpumask that doesn't cover all the cpus in this sched_domain_span(sd)
cpu_smt_mask(target) would already limit to the sched_domain_span(sd) so I am not sure how this can help?
-- Thanks and Regards Srikar Dronamraju
| |