munmap return value

Hi all,

My manpage for munmap(2) says:
On success, munmap returns 0, on failure -1, and errno is set (probably to EINVAL).

In reality munmap always returns 0, except for when the address is not page-aligned (-EINVAL) or if allocation of kernel structures fails (-ENOMEM).

Shouldn't munmap return -EINVAL also if there is nothing mapped at the specified address?

Regards,
Udo.