FTRACE_REF_MAX_SHIFT  318 include/linux/ftrace.h #define FTRACE_FL_MASK		(FTRACE_FL_MASKED_BITS << FTRACE_REF_MAX_SHIFT)
FTRACE_REF_MAX_SHIFT  319 include/linux/ftrace.h #define FTRACE_REF_MAX		((1UL << FTRACE_REF_MAX_SHIFT) - 1)