From: Xunlei Pang xlpang@linux.alibaba.com
mainline inclusion from mainline-v5.10-rc1 commit df3cb4ea1fb63ff326488efd671ba3c39034255e category: bugfix bugzilla: 45956 CVE: NA
--------------------------------
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 wetp.zy@linux.alibaba.com Signed-off-by: Xunlei Pang xlpang@linux.alibaba.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Jiang Biao benbjiang@tencent.com Reviewed-by: Vincent Guittot vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/1600930127-76857-1-git-send-email-xlpang@linux.ali... Signed-off-by: Liu Chao liuchao173@huawei.com Reviewed-by: Jian Cheng cj.chengjian@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- 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 2aca6f86eb34..97e956012a60 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6237,7 +6237,8 @@ static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int t return -1;
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 (available_idle_cpu(cpu) || sched_idle_cpu(cpu)) return cpu;