NMI_BITS           40 include/linux/preempt_mask.h #define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
NMI_BITS           50 include/linux/preempt_mask.h #define PREEMPT_ACTIVE_SHIFT	(NMI_SHIFT + NMI_BITS)