linux-kernel - Re: [PATCH 0/2 v2] remove PF_MEMALLOC

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Message-ID: <ZtiSWUxMQSBzN9cr@tiehlicka>
Date: Wed, 4 Sep 2024 19:01:13 +0200
From: Michal Hocko <mhocko@...e.com>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Christoph Hellwig <hch@....de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Yafang Shao <laoar.shao@...il.com>, jack@...e.cz,
	Vlastimil Babka <vbabka@...e.cz>,
	Dave Chinner <dchinner@...hat.com>,
	Christian Brauner <brauner@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>, linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org, linux-bcachefs@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2 v2] remove PF_MEMALLOC_NORECLAIM

On Wed 04-09-24 12:27:04, Kent Overstreet wrote:
> On Tue, Sep 03, 2024 at 07:13:42AM GMT, Christoph Hellwig wrote:
> > On Mon, Sep 02, 2024 at 02:52:52PM -0700, Andrew Morton wrote:
> > > It would be helpful to summarize your concerns.
> > 
> > And that'd better be a really good argument for a change that was
> > pushed directly to Linus bypassing the maintainer after multiple
> > reviewers pointed out it was broken.  This series simply undoes the
> > damage done by that, while also keeping the code dependend on it
> > working.
> 
> Well, to be blunt, I thought the "we don't want the allocator to even
> know if we're in a non-sleepable context" argument was too crazy to have
> real support, and moving towards PF_MEMALLOC flags is something we've
> been talking about quite a bit going back years.
> 
> Little did I know the minefield I was walking into...

There is a lot of historical baggage and several people tried to explain
that things are quite complex and you cannot simply apply design choices
same way as if you were developing something from scratch. 

> But the disccussion seems to finally be cooling off and going in a more
> productive direction.

Reality check: https://lore.kernel.org/all/8734mitahm.fsf@trenco.lwn.net/T/#u
-- 
Michal Hocko
SUSE Labs