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

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Message-ID: <a8aedeb6-2179-4e53-8310-5b81438c2b80@redhat.com>
Date: Thu, 22 May 2025 14:45:30 +0200
From: David Hildenbrand <david@...hat.com>
To: Johannes Weiner <hannes@...xchg.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Shakeel Butt <shakeel.butt@...ux.dev>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "Liam R . Howlett" <Liam.Howlett@...cle.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 21.05.25 19:32, Johannes Weiner wrote:
> On Wed, May 21, 2025 at 05:21:19AM +0100, Lorenzo Stoakes 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.

As stated elsewhere (e.g., THP cabal yesterday): mctrl() or sth like 
that might be better.

... or anything else that doesn't (ab)use the "advise" terminology in an 
interface that will not only consume advises.

>>
>> 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.
> 
> That's an interesting idea.
> 
> So we'd have THP policies and Barry's FADE_ON_DEATH to start; and it
> might also be a good fit for the coredump stuff and ksm if we wanted
> to incorporate them into that (although it would duplicate the
> existing proc/prctl knobs). The other MMF_s are internal AFAICS.
> 
> I think my main concern would be making something very generic and
> versatile without having sufficiently broad/popular usecases for it.
> 
> But no strong feelings either way. Like I said, I don't have a strong
> dislike for prctl(), but this idea would obviously be cleaner if we
> think there is enough of a demand for a new syscall.

Same here. I am not 100% sure process_madvise() is really the right 
thing to extend, but I do enjoy the SET_DEFAULT_EXEC option. I am also 
not a big fan of prctl() ...

-- 
Cheers,

David / dhildenb