linux-kernel - Re: [RFC PATCH v2 0/4] mm/madvise: remove redundant mmap_lock operations from process

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Message-ID: <62651652-0f51-420e-a203-80711424eb20@lucifer.local>
Date: Fri, 31 Jan 2025 17:53:17 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>, SeongJae Park <sj@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Shakeel Butt <shakeel.butt@...ux.dev>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [RFC PATCH v2 0/4] mm/madvise: remove redundant mmap_lock
 operations from process_madvise()

On Fri, Jan 31, 2025 at 04:55:05PM +0000, Lorenzo Stoakes wrote:
> On Fri, Jan 31, 2025 at 11:04:51AM -0500, Liam R. Howlett wrote:
> > * SeongJae Park <sj@...nel.org> [250116 20:31]:
> > > process_madvise() calls do_madvise() for each address range.  Then, each
> > > do_madvise() invocation holds and releases same mmap_lock.  Optimize the
> > > redundant lock operations by splitting do_madvise() internal logics
> > > including the mmap_lock operations, and calling the small logics
> > > directly from process_madvise() in a sequence that removes the redundant
> > > locking.
> > >
> > > Changes from RFC v1 (20250111004618.1566-1-sj@...nel.org)
> > > - Split out do_madvise() and use those from vector_madvise(), instead of
> > >   adding a flag to do_madvise() (Liam R. Howlett)
> >
> > I was waiting for a non-RFC to re-examine the series.  It looks like a
> > good clean up.
> >
> > Do you think you'll send out a non-RFC version soon?
>
> This is definitely a great cleanup, there's a problem with patch 3/3, but
> SJ - feel free to un-RFC with the fix I suggested - and then happy to give
> R-b and T-b tags!

Liam's pedantry brought me here ;)

Obviously by 3/3 I mean 4/4 here.

Maybe not obviously. But anyway.

>
> Thanks for doing this!
>
> Cheers, Lorenzo
>
> >
> > >
> > > SeongJae Park (4):
> > >   mm/madvise: split out mmap locking operations for madvise()
> > >   mm/madvise: split out madvise input validity check
> > >   mm/madvise: split out madvise() behavior execution
> > >   mm/madvise: remove redundant mmap_lock operations from
> > >     process_madvise()
> > >
> > >  mm/madvise.c | 150 +++++++++++++++++++++++++++++++++++----------------
> > >  1 file changed, 103 insertions(+), 47 deletions(-)
> > >
> > >
> > > base-commit: b43ba6938d01ad4487028592109d4116a28b7afa
> > > --
> > > 2.39.5