linux-kernel - Re: [PATCH v5 0/6] add mTHP support for anonymous shmem

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Message-ID: <Zob8xI-LWe9H_iJs@casper.infradead.org>
Date: Thu, 4 Jul 2024 20:49:24 +0100
From: Matthew Wilcox <willy@...radead.org>
To: David Hildenbrand <david@...hat.com>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>, akpm@...ux-foundation.org,
	hughd@...gle.com, wangkefeng.wang@...wei.com, ying.huang@...el.com,
	21cnbao@...il.com, ryan.roberts@....com, shy828301@...il.com,
	ziy@...dia.com, ioworker0@...il.com, da.gomez@...sung.com,
	p.raghav@...sung.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/6] add mTHP support for anonymous shmem

On Thu, Jul 04, 2024 at 09:19:10PM +0200, David Hildenbrand wrote:
> On 04.07.24 21:03, David Hildenbrand wrote:
> > > shmem has two uses:
> > > 
> > >    - MAP_ANONYMOUS | MAP_SHARED (this patch set)
> > >    - tmpfs
> > > 
> > > For the second use case we don't want controls *at all*, we want the
> > > same heiristics used for all other filesystems to apply to tmpfs.
> > 
> > As discussed in the MM meeting, Hugh had a different opinion on that.
> 
> FWIW, I just recalled that I wrote a quick summary:
> 
> https://lkml.kernel.org/r/f1783ff0-65bd-4b2b-8952-52b6822a0835@redhat.com
> 
> I believe the meetings are recorded as well, but never looked at recordings.

That's not what I understood Hugh to mean.  To me, it seemed that Hugh
was expressing an opinion on using shmem as shmem, not as using it as
tmpfs.

If I misunderstood Hugh, well, I still disagree.  We should not have
separate controls for this.  tmpfs is just not that special.