linux-kernel - Re: [PATCH v2 00/33] Per-VMA locks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230127145138.8cc44bf00ebf289dffec0975@linux-foundation.org>
Date:   Fri, 27 Jan 2023 14:51:38 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
        vbabka@...e.cz, hannes@...xchg.org, mgorman@...hsingularity.net,
        dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com,
        peterz@...radead.org, ldufour@...ux.ibm.com, paulmck@...nel.org,
        mingo@...hat.com, will@...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, punit.agrawal@...edance.com,
        lstoakes@...il.com, peterjung1337@...il.com, rientjes@...gle.com,
        axelrasmussen@...gle.com, joelaf@...gle.com, minchan@...gle.com,
        rppt@...nel.org, jannh@...gle.com, shakeelb@...gle.com,
        tatashin@...gle.com, edumazet@...gle.com, gthelen@...gle.com,
        gurua@...gle.com, arjunroy@...gle.com, soheil@...gle.com,
        leewalsh@...gle.com, posk@...gle.com, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH v2 00/33] Per-VMA locks

On Fri, 27 Jan 2023 11:40:37 -0800 Suren Baghdasaryan <surenb@...gle.com> wrote:

> Per-vma locks idea that was discussed during SPF [1] discussion at LSF/MM
> last year [2], which concluded with suggestion that “a reader/writer
> semaphore could be put into the VMA itself; that would have the effect of
> using the VMA as a sort of range lock. There would still be contention at
> the VMA level, but it would be an improvement.” This patchset implements
> this suggested approach.

I think I'll await reviewer/tester input for a while.

> The patchset implements per-VMA locking only for anonymous pages which
> are not in swap and avoids userfaultfs as their implementation is more
> complex. Additional support for file-back page faults, swapped and user
> pages can be added incrementally.

This is a significant risk.  How can we be confident that these as yet
unimplemented parts are implementable and that the result will be good?