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

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Message-ID: <CAMZfGtW0PqU6SLihLABA8rU+FuBqm8NksDW=EkLXy1RZfYeDGA@mail.gmail.com>
Date:   Tue, 15 Sep 2020 23:28:01 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Jonathan Corbet <corbet@....net>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>, mingo@...hat.com,
        bp@...en8.de, x86@...nel.org, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org,
        Peter Zijlstra <peterz@...radead.org>, viro@...iv.linux.org.uk,
        Andrew Morton <akpm@...ux-foundation.org>, paulmck@...nel.org,
        mchehab+huawei@...nel.org, pawan.kumar.gupta@...ux.intel.com,
        Randy Dunlap <rdunlap@...radead.org>, oneukum@...e.com,
        anshuman.khandual@....com, jroedel@...e.de, almasrymina@...gle.com,
        David Rientjes <rientjes@...gle.com>,
        linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        linux-fsdevel@...r.kernel.org
Subject: Re: [External] Re: [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap
 pages of hugetlb page

On Tue, Sep 15, 2020 at 10:32 PM Matthew Wilcox <willy@...radead.org> wrote:
>
> 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.

Can you elaborate on the problem? Thanks so much.

>
> 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.

Welcome, we can work together.


-- 
Yours,
Muchun