Message-ID: <20251201164338.GA430226@cmpxchg.org>
Date: Mon, 1 Dec 2025 11:43:38 -0500
From: Johannes Weiner <hannes@...xchg.org>
To: Chris Li <chrisl@...nel.org>
Cc: Nhat Pham <nphamcs@...il.com>, Rik van Riel <riel@...riel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kairui Song <kasong@...cent.com>,
	Kemeng Shi <shikemeng@...weicloud.com>, Baoquan He <bhe@...hat.com>,
	Barry Song <baohua@...nel.org>, Yosry Ahmed <yosry.ahmed@...ux.dev>,
	Chengming Zhou <chengming.zhou@...ux.dev>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, pratmal@...gle.com,
	sweettea@...gle.com, gthelen@...gle.com, weixugc@...gle.com
Subject: Re: [PATCH RFC] mm: ghost swapfile support for zswap

On Sun, Nov 30, 2025 at 12:38:38AM +0400, Chris Li wrote:
> On Sat, Nov 29, 2025 at 12:46 AM Nhat Pham <nphamcs@...il.com> wrote:
> >
> > On Thu, Nov 27, 2025 at 11:10 AM Chris Li <chrisl@...nel.org> wrote:
> > >
> > > On Thu, Nov 27, 2025 at 6:28 AM Rik van Riel <riel@...riel.com> wrote:
> > > >
> > > > Sorry, I am talking about upstream.
> > >
> > > So far I have not had a pleasant upstream experience when submitting
> > > this particular patch to upstream.
> > >
> > > > I really appreciate anybody participating in Linux
> > > > kernel development. Linux is good because different
> > > > people bring different perspectives to the table.
> > >
> > > Of course everybody is welcome. However, NACK without technical
> > > justification is very bad for upstream development. I can't imagine
> > > what a new hacker would think after going through what I have gone
> > > through for this patch. He/she will likely quit contributing upstream.
> > > This is not the kind of welcome we want.
> > >
> > > Nhat needs to be able to technically justify his NACK as a maintainer.
> > > Sorry there is no other way to sugar coat it.
> >
> > I am NOT the only zswap maintainer who expresses concerns. Other
> > people also have their misgivings, so I have let them speak and not
> > put words in their mouths.
> 
> You did not mention the fact that both two NACK from zswap maintainers
> are from the same company. I assume you have some kind of team sync.
> There is a term for that, called "person acting in concert".

For the benefit of anybody following this from the sidelines, the
third zswap maintainer also expressed concerns about Chris's proposal
upthread. He works for the same company as Chris.

The reality is that Chris is failing to convince others of his design
direction, and is now obviously resorting to manipulation and hominem
attacks.

During the course of this thread, Chris has asked for "a little faith"
that his idea will work for all stated requirements, without deeming
it necessary to explain how.

When probed on technical details, he stated that he doesn't like to
plan that far ahead, and prefers having somebody else iron out the
implementation details. He also referred to high-level slides from his
LSFMM '24 session - which was received thusly[1]:

  Matthew Wilcox agreed, warning Li that he was setting himself up for "a world of pain".

  Jan Kara said that existing filesystem designs are not suited to this task

  Hildenbrand said that this plan was introducing too much complexity

His first response to criticism was to invoke his <4 week status of
swap maintainer.

Meanwhile, the design direction that Chris is construing as a single
company conspiracy is anything but. The collaborative origins of these
patches are well documented. Chris was CC'd on those RFCs. He notably
did not engage in them. He is now lying about the narrative and
choosing to attack these patches in bad faith and out of context.

This pattern of behavior gives me low confidence that Chris is able to
collaborate and compromise on a design that works for all users.

And while Chris has been quite vocal and opinionated in mailing list
discussions, his actual code contributions to the kernel do not
instill confidence that he can solve this problem by himself, either.

[1] https://lwn.net/Articles/974587/

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