MAX_LOCKDEP_KEYS_BITS  212 include/linux/lockdep.h #define MAX_LOCKDEP_KEYS		((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
MAX_LOCKDEP_KEYS_BITS  237 include/linux/lockdep.h 	unsigned int			class_idx:MAX_LOCKDEP_KEYS_BITS;