linux-kernel - Re: [RFC PATCH] mm/madvise: remove redundant mmap_lock operations from process

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Message-Id: <20250114195458.53517-1-sj@kernel.org>
Date: Tue, 14 Jan 2025 11:54:58 -0800
From: SeongJae Park <sj@...nel.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: SeongJae Park <sj@...nel.org>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	David Hildenbrand <david@...hat.com>,
	Liam.Howlett@...cle.com,
	Vlastimil Babka <vbabka@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jens Axboe <axboe@...nel.dk>,
	Pavel Begunkov <asml.silence@...il.com>,
	damon@...ts.linux.dev,
	io-uring@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [RFC PATCH] mm/madvise: remove redundant mmap_lock operations from process_madvise()

On Tue, 14 Jan 2025 18:47:15 +0000 Lorenzo Stoakes <lorenzo.stoakes@...cle.com> wrote:

> On Tue, Jan 14, 2025 at 10:13:40AM -0800, Shakeel Butt wrote:
> > Ccing relevant folks.
> 
> Thanks Shakeel!

Thank you Shakeel, too!

> 
> A side-note, I really wish there was a better way to get cc'd, since I
> fundamentally changed process_madvise() recently and was the main person
> changing this code lately, but on the other hand -
> scripts/get_maintainers.pl gets really really noisy if you try to use this
> kind of stat - so I in no way blame SJ for missing me.

Yes, I always feeling finding not too many, not too less, but only appropriate
recipients for patches is not easy.  Just FYI, I use get_maintainers.pl with
--nogit option[1] and add more recipients based on additional logics[2] that
based on my past experiences and discussions, by default.  And then I run
get_maintainers.pl without --nogit option if I get no response more than I
expected.

I will keep Shakeel-aded recipients for next spins of this patch, anyway.

> 
> Thankfully Shakeel kindly stepped in to make me aware :)
> 
> SJ - I will come back to you later, as it's late here and my brain is fried
> - but I was already thinking of doing something _like_ this, as I noticed
> for the purposes of self-process_madvise() operations (which I unrestricted
> for guard page purposes) - we are hammering locks in a way that we know we
> don't necessarily need to do.
> 
> So this is serendipitous for me! :) But I need to dig into your actual
> implementation to give feedback here.
> 
> Will come back to this in due course :)

No worry, no rush.  Please take your time :)

[1] https://github.com/sjp38/hackermail/blob/master/src/hkml_patch_format.py#L45
[2] https://github.com/sjp38/hackermail/blob/master/src/hkml_patch_format.py#L31


Thanks,
SJ

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