netdev - Re: [PATCH 4.14 0/4] netfilter: xt_connlimit: backport upstream fixes for race in connection counting

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Message-ID: <CAO9xwp3BDgoDUpq=tW_eXbq6_YzVkuD-zW5teO-AaD5rE=We9Q@mail.gmail.com>
Date:   Wed, 2 Jan 2019 17:52:00 -0200
From:   Mauricio Faria de Oliveira <mfo@...onical.com>
To:     Florian Westphal <fw@...len.de>
Cc:     stable@...r.kernel.org, netdev@...r.kernel.org,
        Alakesh Haloi <alakeshh@...zon.com>,
        Nivedita Singhvi <nivedita.singhvi@...onical.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        "David S. Miller" <davem@...emloft.net>,
        Yi-Hung Wei <yihung.wei@...il.com>
Subject: Re: [PATCH 4.14 0/4] netfilter: xt_connlimit: backport upstream fixes
 for race in connection counting

Florian,

On Wed, Jan 2, 2019 at 3:17 PM Florian Westphal <fw@...len.de> wrote:
>
> Mauricio Faria de Oliveira <mfo@...onical.com> wrote:
<snip>
> > Either way, the suggested mainline fix does actually fix the issue in 4.14
> > for at least one environment. So, it might well be the case that Alakesh's
> > test environment has differences/subtleties that leads to more connections
> > accepted, and more commits are needed for that particular environment type.
>
> nf_conncount has a design flaw that is only closed in nf.git/net.git
> at the time of this writing, so results with earlier kernels (including
> 4.20) might just fail with different bugs.
>
> 4.14 doesn't have those problems, so I think this series (aside from the
> nit in patch 4/4) indeed should fix the issue reported.

Thanks for mentioning that. It offers some relief about the different
results observed.

> > But for now, with one bare-metal environment (24-core server, 4-core client)
> > verified, I thought of submitting the patches for review/comments/testing,
> > then looking for additional fixes for that environment separately.
>
> 4.14 should be good after this afaics.
>
> Thanks a lot for doing this backport and the details testing
> information.

Thank you a lot for your quick and careful review.
I'll build/test/submit a PATCH v2 series (with that fix to patch 4/4) shortly.

cheers,

-- 
Mauricio Faria de Oliveira