linux-kernel - Re: [RFC PATCH 0/5] add process_madvise() flags to modify behaviour

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Message-ID: <e4d9dd63-5000-4939-b09c-c322d41a9d70@lucifer.local>
Date: Wed, 21 May 2025 17:49:15 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        David Hildenbrand <david@...hat.com>, Vlastimil Babka <vbabka@...e.cz>,
        Jann Horn <jannh@...gle.com>, Arnd Bergmann <arnd@...db.de>,
        Christian Brauner <brauner@...nel.org>, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        SeongJae Park <sj@...nel.org>, Usama Arif <usamaarif642@...il.com>
Subject: Re: [RFC PATCH 0/5] add process_madvise() flags to modify behaviour

On Wed, May 21, 2025 at 09:28:43AM -0700, Shakeel Butt wrote:
> On Wed, May 21, 2025 at 05:21:19AM +0100, Lorenzo Stoakes wrote:
> > On Tue, May 20, 2025 at 03:02:09PM -0700, Shakeel Butt wrote:
> >
> [...]
> >
> > So, something Liam mentioned off-list was the beautifully named
> > 'mmadvise()'. Idea being that we have a system call _explicitly for_
> > mm-wide modifications.
> >
> > With Barry's series doing a prctl() for something similar, and a whole host
> > of mm->flags existing for modifying behaviour, it would seem a natural fit.
> >
> > I could do a respin that does something like this instead.
> >
>
> Please let's first get consensus on this before starting the work.

With respect Shakeel, I'll work on whatever I want, whenever I want.

These are RFC's, that is, Requests for Comment, intended to explore new
ideas and to show how they might look in practice so we can make the right
choice.

I feel like I've said this more than once now...!

>
> Usama, David, Johannes and others, WDYT?
>

But obviously it would be good to get some input from others, more so from
the actual maintainer (David) and reviewers though obviously everybody's
opinion matters.

Overall my view is prctl() is really something we should avoid here unless
we have absolutely no other choice. I've gone into detail as to why already
so won't belabour the point.

Thanks.