do_madvise
extern int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior);
ret = do_madvise(current->mm, ma->addr, ma->len, ma->advice);
applied = do_madvise(mm, start, len, behavior) ? 0 : len;
return do_madvise(current->mm, start, len_in, behavior);