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Date: Thu, 22 Jul 2021 03:24:46 +0100
From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Joao Martins <joao.m.martins@oracle.com>, linux-mm@kvack.org,
	Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	Jason Gunthorpe <jgg@ziepe.ca>, John Hubbard <jhubbard@nvidia.com>,
	Jane Chu <jane.chu@oracle.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Jonathan Corbet <corbet@lwn.net>, nvdimm@lists.linux.dev,
	linux-doc@vger.kernel.org
Subject: Re: [PATCH v3 00/14] mm, sparse-vmemmap: Introduce compound pagemaps
Message-ID: <YPjW7tu1NU0iRaH9@casper.infradead.org>
References: <20210714193542.21857-1-joao.m.martins@oracle.com>
 <20210714144830.29f9584878b04903079ef7eb@linux-foundation.org>
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In-Reply-To: <20210714144830.29f9584878b04903079ef7eb@linux-foundation.org>

On Wed, Jul 14, 2021 at 02:48:30PM -0700, Andrew Morton wrote:
> On Wed, 14 Jul 2021 20:35:28 +0100 Joao Martins <joao.m.martins@oracle.com> wrote:
> 
> > This series, attempts at minimizing 'struct page' overhead by
> > pursuing a similar approach as Muchun Song series "Free some vmemmap
> > pages of hugetlb page"[0] but applied to devmap/ZONE_DEVICE which is now
> > in mmotm. 
> > 
> > [0] https://lore.kernel.org/linux-mm/20210308102807.59745-1-songmuchun@bytedance.com/
> 
> [0] is now in mainline.
> 
> This patch series looks like it'll clash significantly with the folio
> work and it is pretty thinly reviewed, so I think I'll take a pass for
> now.  Matthew, thoughts?

I had a look through it, and I don't see anything that looks like it'll
clash with the folio patches.  The folio work really touches the page
cache for now, and this seems mostly to touch the devmap paths.

It would be nice to convert the devmap code to folios too, but that
can wait.  The mess with page refcounts needs to be sorted out first.