hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7FJB5

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A warn may be triggered during reboot, as follows:

reboot ->kernel_restart ->machine_restart ->smp_send_stop --- ipi handler set_cpu_online(cpu, false)

balance_callback -> __balance_callback ->push_rt_task -> find_lock_lowest_rq --- offline cpu in vec->mask not be cleared -> find_lowest_rq -> cpupri_find -> cpupri_find_fitness -> __cpupri_find [cpumask_and(..., vec->mask)] -> set_task_cpu(next_task, lowest_rq->cpu) --- WARN_ON(!oneline(cpu)

So add !cpu_online(lowest_rq->cpu) check before set_task_cpu(). The fix does not completely fix the problem, since cpu_online_mask may be cleared after check.

Fixes: 4ff9083b8a9a8 ("sched/core: WARN() when migrating to an offline CPU") Signed-off-by: Hui Tang tanghui20@huawei.com --- kernel/sched/rt.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 0f349d8d076d..ca868c04ff24 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1941,6 +1941,9 @@ static int push_rt_task(struct rq *rq) goto retry; }

+ if (unlikely(!cpu_online(lowest_rq->cpu))) + goto out; + deactivate_task(rq, next_task, 0); set_task_cpu(next_task, lowest_rq->cpu); activate_task(lowest_rq, next_task, 0);