Re: [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page

[Matthew Wilcox]

On Tue, Sep 15, 2020 at 08:59:23PM +0800, Muchun Song wrote:
> This patch series will free some vmemmap pages(struct page structures)
> associated with each hugetlbpage when preallocated to save memory.

It would be lovely to be able to do this.  Unfortunately, it's completely
impossible right now.  Consider, for example, get_user_pages() called
on the fifth page of a hugetlb page.

I've spent a lot of time thinking about this, and there's a lot of work
that needs to happen before we can do this, mostly in device drivers.
Do you want to help?  It's a multi-year project.