I'm missing something here. Assuming there are pages at 0k, 16k, 32k etc - all of those pages are aligned on 4k boundaries as 4k > 16k. So code written with the assumption that its pages are 4k aligned should have that assumption met when running with 16k pages. It is still early here and I have only had one cup of coffee. Am I misunderstanding something really obvious?
x86 app might mmap 8kb, then munmap the second 4kb and expect that to work. But not possible on 16k pages.