From a498bc27ac8e6092b3ba403ac917133cab67cf0e Mon Sep 17 00:00:00 2001 From: Xunlei Pang Date: Thu, 24 Sep 2020 14:48:47 +0800 Subject: [PATCH] sched/fair: Fix wrong cpu selecting from isolated domain ANBZ: #1468 commit df3cb4ea1fb63ff326488efd671ba3c39034255e upstream 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. Steps to reproduce on my 31-CPU hyperthreads machine: 1. with boot parameter: "isolcpus=domain,2-31" (thread lists: 0,16 and 1,17) 2. cgcreate -g cpu:test; cgexec -g cpu:test "test_threads" 3. some threads will be migrated to the isolated cpu16~17. 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 Signed-off-by: Xunlei Pang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Jiang Biao Reviewed-by: Vincent Guittot Link: https://lkml.kernel.org/r/1600930127-76857-1-git-send-email-xlpang@linux.alibaba.com Signed-off-by: Qinyun Tan Reviewed-by: Xunlei Pang --- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 380df348cd57..f94c24dd315f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7469,7 +7469,8 @@ static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int t is_expellee = is_expellee_task(p); for_each_cpu(cpu, cpu_smt_mask(target)) { - if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) + if (!cpumask_test_cpu(cpu, &p->cpus_allowed) || + !cpumask_test_cpu(cpu, sched_domain_span(sd))) continue; if (id_idle_cpu(p, cpu, is_expellee, NULL)) return cpu; -- Gitee