Re: [PATCH 3/6] hugetlb: add free page reporting support

From: Liang Li
Date: Wed Jan 06 2021 - 22:39:16 EST

On Thu, Jan 7, 2021 at 12:08 AM Michal Hocko <mhocko@xxxxxxxx> wrote:
> On Tue 05-01-21 22:49:21, Liang Li wrote:
> > hugetlb manages its page in hstate's free page list, not in buddy
> > system, this patch try to make it works for hugetlbfs. It canbe
> > used for memory overcommit in virtualization and hugetlb pre zero
> > out.
> David has layed down some more fundamental questions in the reply to the
> cover letter (btw. can you fix your scripts to send patches and make all
> the patches to be in reply to the cover letter please?). But I would

Do you mean attach the patches in the email for the cover letter ?

> like to point out that this changelog would need to change a lot as
> well. It doesn't explain really what, why and how. E.g. what would any
> guest gain by being able to report free huge pages? What would guarantee
> that the pool is replenished when there is a demand? Can this make the
> fault fail or it just takes more time to be satisfied? Why did you
> decide that the reporting infrastructure should be abused to do the
> zeroying? I do remember Alexander pushing back against that and so you
> should better have a very strong arguments to proceed that way.
> I am pretty sure there are more questions to come when more details are
> uncovered.
> --
> Michal Hocko
> SUSE Labs

I will try to add more detail about the aspect you referred to. Thanks!