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From:   Suren Baghdasaryan <surenb@google.com>
Date:   Thu, 29 Dec 2022 09:21:50 -0800
Message-ID: <CAJuCfpGXvMKsO13S_wyNjEUReW9q_duWEO8HG4fBLWOoibBuug@mail.gmail.com>
Subject: Re: [QUESTION] about the maple tree and current status of mmap_lock scalability
To:     Lorenzo Stoakes <lstoakes@gmail.com>
Cc:     Matthew Wilcox <willy@infradead.org>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org,
        liam.howlett@oracle.com, ldufour@linux.ibm.com,
        michel@lespinasse.org, vbabka@suse.cz, linux-kernel@vger.kernel.org
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On Thu, Dec 29, 2022 at 9:10 AM Lorenzo Stoakes <lstoakes@gmail.com> wrote:
>
> On Thu, Dec 29, 2022 at 04:51:37PM +0000, Matthew Wilcox wrote:
> > The mmap_lock is taken for many, many things.  [snip]
>
> I am currently describing the use of this lock (for 6.0) in the book and it is
> striking just how broadly it's used. I'm diagramming it out for 'core' users,
> i.e. non-driver and non-some other things, but even constraining that leaves a
> HUGE number of users. I've also documented the 'unexpected' uses of the
> page_table_lock, which seems to have been significantly improved over time but
> still a few cases remain!
>
> Am happy to give you (+ anybody else on MAINTAINERS list) an early copy of the
> relevant bit (once I've finished the diagrams anyway) if that'd be helpful!

Yes please, that would be interesting.

>
> Now if you guys could stop obsoleting my work that'd be great ;)