linux-kernel - Re: [RFC PATCH RESEND 00/28] per-VMA locks proposal

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Date:   Mon, 5 Sep 2022 14:32:00 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, michel@...pinasse.org,
        jglisse@...gle.com, vbabka@...e.cz, hannes@...xchg.org,
        mgorman@...e.de, dave@...olabs.net, willy@...radead.org,
        liam.howlett@...cle.com, peterz@...radead.org,
        ldufour@...ux.ibm.com, laurent.dufour@...ibm.com,
        paulmck@...nel.org, luto@...nel.org, songliubraving@...com,
        peterx@...hat.com, david@...hat.com, dhowells@...hat.com,
        hughd@...gle.com, bigeasy@...utronix.de, kent.overstreet@...ux.dev,
        rientjes@...gle.com, axelrasmussen@...gle.com, joelaf@...gle.com,
        minchan@...gle.com, kernel-team@...roid.com, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH RESEND 00/28] per-VMA locks proposal

Unless I am missing something, this is not based on the Maple tree
rewrite, right? Does the change in the data structure makes any
difference to the approach? I remember discussions at LSFMM where it has
been pointed out that some issues with the vma tree are considerably
simpler to handle with the maple tree.

On Thu 01-09-22 10:34:48, Suren Baghdasaryan wrote:
[...]
> One notable way the implementation deviates from the proposal is the way
> VMAs are marked as locked. Because during some of mm updates multiple
> VMAs need to be locked until the end of the update (e.g. vma_merge,
> split_vma, etc).

I think it would be really helpful to spell out those issues in a greater
detail. Not everybody is aware of those vma related subtleties.

Thanks for working on this Suren!
-- 
Michal Hocko
SUSE Labs