Re: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings
From: Christopher Lameter
Date: Tue Oct 29 2019 - 03:08:45 EST
On Mon, 28 Oct 2019, Kirill A. Shutemov wrote:
> Setting a single 4k page non-present in the direct mapping will require
> splitting 2M or 1G page we usually map direct mapping with. And it's one
> way road. We don't have any mechanism to map the memory with huge page
> again after the application has freed the page.
>
> It might be okay if all these pages cluster together, but I don't think we
> have a way to achieve it easily.
Set aside a special physical memory range for this and migrate the
page to that physical memory range when MAP_EXCLUSIVE is specified?
Maybe some processors also have hardware ranges that offer additional
protection for stuff like that?