Question

I use vm_insert_page to insert a page to a userspace VMA, now I want to remove that page from that VMA. But I don’t want the whole VMA got unmapped, just that exact page range only. Which kernel function should I call?

Answer 1

You don’t need any special kernel code in order to accomplish this. All you need is for user-space to call munmap() system call on the page that you want to unmap. Another option is to call do_munmap() directly from kernel. Look at the implementation of munmap() system call.