sched_setscheduler() needs to acquire cpuset_rwsem, but it is currently
called from an invalid (atomic) context by rcu_spawn_gp_kthread().

Fix that by simply moving sched_setscheduler_nocheck() call outside of
the atomic region, as it doesn't actually require to be guarded by
rcu_node lock.

Suggested-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Juri Lelli <juri.le...@redhat.com>
---
 kernel/rcu/tree.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 980ca3ca643f..32ea75acba14 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3123,13 +3123,13 @@ static int __init rcu_spawn_gp_kthread(void)
        t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name);
        if (WARN_ONCE(IS_ERR(t), "%s: Could not start grace-period kthread, OOM 
is now expected behavior\n", __func__))
                return 0;
+       if (kthread_prio)
+               sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
        rnp = rcu_get_root();
        raw_spin_lock_irqsave_rcu_node(rnp, flags);
        rcu_state.gp_kthread = t;
-       if (kthread_prio) {
+       if (kthread_prio)
                sp.sched_priority = kthread_prio;
-               sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
-       }
        raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
        wake_up_process(t);
        rcu_spawn_nocb_kthreads();
-- 
2.17.2

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