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From:   Shakeel Butt <shakeelb@google.com>
Date:   Sun, 12 Sep 2021 09:05:41 -0700
Message-ID: <CALvZod5vBkoJ5PpXTW7CCMD9UjMkqK2sQuxK_LXn+W8ddDP5Nw@mail.gmail.com>
Subject: Re: [PATCH] ipc: remove memcg accounting for sops objects in do_semtimedop()
To:     Vasily Averin <vvs@virtuozzo.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Michal Hocko <mhocko@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>, kernel@openvz.org,
        Cgroups <cgroups@vger.kernel.org>
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On Sat, Sep 11, 2021 at 12:40 AM Vasily Averin <vvs@virtuozzo.com> wrote:
>
> Linus proposes to revert an accounting for sops objects in
> do_semtimedop() because it's really just a temporary buffer
> for a single semtimedop() system call.
>
> This object can consume up to 2 pages, syscall is sleeping one,
> size and duration can be controlled by user, and this allocation
> can be repeated by many thread at the same time.
>
> However Shakeel Butt pointed that there are much more popular objects
> with the same life time and similar memory consumption, the accounting
> of which was decided to be rejected for performance reasons.
>
> In addition, any usual task consumes much more accounted memory,
> so 2 pages of this temporal buffer can be safely ignored.
>
> Link: https://patchwork.kernel.org/project/linux-fsdevel/patch/20171005222144.123797-1-shakeelb@google.com/
>
> Fixes: 18319498fdd4 ("memcg: enable accounting of ipc resources")
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>

Thanks Vasily.

Acked-by: Shakeel Butt <shakeelb@google.com>