linux-kernel - Re: [PATCH v5] mm/oom_kill.c: futex: Close a race between do_exit and the oom

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Message-ID: <20220322025724.j3japdo5qocwgchz@offworld>
Date:   Mon, 21 Mar 2022 19:57:24 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Nico Pache <npache@...hat.com>
Cc:     Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        Joel Savitz <jsavitz@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Rafael Aquini <aquini@...hat.com>,
        Waiman Long <longman@...hat.com>, Baoquan He <bhe@...hat.com>,
        Christoph von Recklinghausen <crecklin@...hat.com>,
        Don Dutile <ddutile@...hat.com>,
        "Herton R . Krzesinski" <herton@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        Andre Almeida <andrealmeid@...labora.com>,
        David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH v5] mm/oom_kill.c: futex: Close a race between do_exit
 and the oom_reaper

On Mon, 21 Mar 2022, Nico Pache wrote:

>We could proceed with the V3 approach; however if we are able to find a complete
>solution that keeps both functionalities (Concurrent OOM Reaping & Robust Futex)
>working, I dont see why we wouldnt go for it.

Because semantically killing the process is, imo, the wrong thing to do. My
performance argument before however is bogus as the overhead of robust futexes
is pretty negligible within the lifetime of a lock. That said, the users still
have good(?) reasons for not wanting the lock holder to crash on them.

Thanks,
Davidlohr