SPINLOCK_SIZE 23 include/linux/lockref.h IS_ENABLED(CONFIG_SMP) && SPINLOCK_SIZE <= 4) SPINLOCK_SIZE 25 include/linux/mm_types_task.h #define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8) SPINLOCK_SIZE 24 kernel/bounds.c DEFINE(SPINLOCK_SIZE, sizeof(spinlock_t));