From: Shakeel Butt <shakeelb@google.com>
To: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>, Roman Gushchin <guro@fb.com>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Greg Thelen <gthelen@google.com>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH v3] cgroup: memcg: net: do not associate sock with unrelated cgroup
Date: Wed, 26 Feb 2020 12:02:31 -0800 [thread overview]
Message-ID: <CALvZod5TsauERhaCqa1OZp4FaX4nq_UBL84=siESEG=Uk4LYuQ@mail.gmail.com> (raw)
In-Reply-To: <20200226.110749.77396284962321904.davem@davemloft.net>
On Wed, Feb 26, 2020 at 11:07 AM David Miller <davem@davemloft.net> wrote:
>
> From: Shakeel Butt <shakeelb@google.com>
> Date: Thu, 20 Feb 2020 17:46:04 -0800
>
> > We are testing network memory accounting in our setup and noticed
> > inconsistent network memory usage and often unrelated cgroups network
> > usage correlates with testing workload. On further inspection, it
> > seems like mem_cgroup_sk_alloc() and cgroup_sk_alloc() are broken in
> > IRQ context specially for cgroup v1.
> >
> > mem_cgroup_sk_alloc() and cgroup_sk_alloc() can be called in IRQ context
> > and kind of assumes that this can only happen from sk_clone_lock()
> > and the source sock object has already associated cgroup. However in
> > cgroup v1, where network memory accounting is opt-in, the source sock
> > can be unassociated with any cgroup and the new cloned sock can get
> > associated with unrelated interrupted cgroup.
> >
> > Cgroup v2 can also suffer if the source sock object was created by
> > process in the root cgroup or if sk_alloc() is called in IRQ context.
> > The fix is to just do nothing in interrupt.
> >
> > WARNING: Please note that about half of the TCP sockets are allocated
> > from the IRQ context, so, memory used by such sockets will not be
> > accouted by the memcg.
>
> Then if we do this then we have to have some kind of subsequent change
> to attach these sockets to the correct cgroup, right?
Currently we can potentially charge wrong cgroup. With this patch that
will be fixed but potentially half of sockets remain unaccounted. I
have a followup (incomplete) patch [1] to fix that. I will send the
next version soon.
[1] https://lore.kernel.org/linux-mm/20200222010456.40635-1-shakeelb@google.com/
prev parent reply other threads:[~2020-02-26 20:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 1:46 [PATCH v3] cgroup: memcg: net: do not associate sock with unrelated cgroup Shakeel Butt
2020-02-26 19:07 ` David Miller
2020-02-26 20:02 ` Shakeel Butt [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CALvZod5TsauERhaCqa1OZp4FaX4nq_UBL84=siESEG=Uk4LYuQ@mail.gmail.com' \
--to=shakeelb@google.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=gthelen@google.com \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=tj@kernel.org \
--cc=vdavydov.dev@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).