How to replace a kernel built-in function

[Xiangfei Jia <xjianz@xxxxxxxxx>]

I want to replace a kernel built-in function, so the function can
perform some special tasks when the kernel calls the function. I want
to know how to write a module to over-write the built-in kernel
functions. For example, I wan to replace the swapping funtion
"rw_swap_page()". How can I do this? (I know how to replace a default
system call, but not this built-in function.)

Thanks!

Fei