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In case of failure to spawn either rcuog or rcuo[p] kthreads for a given rdp, rcu_nocb_rdp_deoffload() needs to be called with the hotplug lock and the barrier_mutex held. However cpus write lock is already held while calling rcutree_prepare_cpu(). It's not possible to call rcu_nocb_rdp_deoffload() from there with just locking the barrier_mutex or this would result in a locking inversion against rcu_nocb_cpu_deoffload() which holds both locks in the reverse order. Simply solve this with inverting the locking order inside rcu_nocb_cpu_[de]offload(). This will be a pre-requisite to toggle NOCB states toward cpusets anyway. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>