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According to the commit log of the patch that added it to the kernel, start_poll_synchronize_rcu_expedited() can be invoked very early, as in long before rcu_init() has been invoked. But before rcu_init(), the rcu_data structure's ->mynode field has not yet been initialized. This means that the start_poll_synchronize_rcu_expedited() function's attempt to set the CPU's leaf rcu_node structure's ->exp_seq_poll_rq field will result in a segmentation fault. This commit therefore causes start_poll_synchronize_rcu_expedited() to set ->exp_seq_poll_rq only after rcu_init() has initialized all CPUs' rcu_data structures' ->mynode fields. It also removes the check from the rcu_init() function so that start_poll_synchronize_rcu_expedited( is unconditionally invoked. Yes, this might result in an unnecessary boot-time grace period, but this is down in the noise. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>