MIGHT_RESCHED_RCU_SHIFT
#define MIGHT_RESCHED_PREEMPT_MASK ((1U << MIGHT_RESCHED_RCU_SHIFT) - 1)
(PREEMPT_LOCK_OFFSET + (1U << MIGHT_RESCHED_RCU_SHIFT))
(rcu_preempt_depth() << MIGHT_RESCHED_RCU_SHIFT)
nested += rcu_preempt_depth() << MIGHT_RESCHED_RCU_SHIFT;
rcu_preempt_depth(), offsets >> MIGHT_RESCHED_RCU_SHIFT);