sched/fair: Fix wrong cpu selecting from isolated domain

mainline inclusion
from mainline-v5.10-rc1
commit df3cb4ea
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I52QKB


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: 10e2f1ac ("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.alibaba.com



Conflicts:
	kernel/sched/fair.c

Signed-off-by: Yu jiahua <yujiahua1@huawei.com>
Reviewed-by: zheng zucheng <zhengzucheng@huawei.com>
Reviewed-by: zheng zucheng <zhengzucheng@huawei.com>
Reviewed-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>