linux-kernel - Re: [PATCH 0/3] mm,thp,rmap: rework the use of subpages

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Date:   Fri, 18 Nov 2022 15:42:34 -0500
From:   Johannes Weiner <hannes@...xchg.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>, Peter Xu <peterx@...hat.com>,
        Yang Shi <shy828301@...il.com>,
        John Hubbard <jhubbard@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Sidhartha Kumar <sidhartha.kumar@...cle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Naoya Horiguchi <naoya.horiguchi@...ux.dev>,
        Mina Almasry <almasrymina@...gle.com>,
        James Houghton <jthoughton@...gle.com>,
        Zach O'Keefe <zokeefe@...gle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 0/3] mm,thp,rmap: rework the use of subpages_mapcount

On Fri, Nov 18, 2022 at 12:18:42PM -0800, Linus Torvalds wrote:
> On Fri, Nov 18, 2022 at 1:08 AM Hugh Dickins <hughd@...gle.com> wrote:
> >
> > Linus was underwhelmed by the earlier compound mapcounts series:
> > this series builds on top of it (as in next-20221117) to follow
> > up on his suggestions - except rmap.c still using lock_page_memcg(),
> > since I hesitate to steal the pleasure of deletion from Johannes.
> 
> This looks good to me. Particularly 2/3 made me go "Aww, yes" but the
> overall line removal stats look good too.
> 
> That said, I only looked at the patches, and not the end result
> itself. But not having the bit spin lock is, I think, a huge
> improvement.
> 
> I do wonder if this should be now just merged with your previous
> series - it looks a bit odd how your previous series adds that
> bitlock, only for it to be immediately removed.
> 
> But if you think the logic ends up being easier to follow this way as
> two separate patch series, I guess I don't care.
> 
> And the memcg locking is entirely a separate issue, and I hope
> Johannes will deal with that.

Yeah, I'll redo the removal on top of this series and resend it.

Thanks