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Date:   Tue, 27 Jul 2021 09:21:00 +0200
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Vasily Averin <vvs@virtuozzo.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>, cgroups@vger.kernel.org,
        Michal Hocko <mhocko@kernel.org>,
        Shakeel Butt <shakeelb@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Roman Gushchin <guro@fb.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 01/10] memcg: enable accounting for mnt_cache entries
Message-ID: <20210727072100.4a3o6tcw7v5ot2lr@wittgenstein>
References: <6f21a0e0-bd36-b6be-1ffa-0dc86c06c470@virtuozzo.com>
 <cover.1627362057.git.vvs@virtuozzo.com>
 <045db11f-4a45-7c9b-2664-5b32c2b44943@virtuozzo.com>
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On Tue, Jul 27, 2021 at 08:33:12AM +0300, Vasily Averin wrote:
> The kernel allocates ~400 bytes of 'strcut mount' for any new mount.
> Creating a new mount namespace clones most of the parent mounts,
> and this can be repeated many times. Additionally, each mount allocates
> up to PATH_MAX=4096 bytes for mnt->mnt_devname.
> 
> It makes sense to account for these allocations to restrict the host's
> memory consumption from inside the memcg-limited container.
> 
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---

Looks good. Thank you!
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

I wonder how much this increases reported memory consumption when you
boot full system containers that run systemd and a bunch of systemd
services that each use a separate mount namespace.