From: Pablo Neira Ayuso <pablo@netfilter•org>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: Jozsef Kadlecsik <kadlec@blackhole•kfki.hu>,
Florian Westphal <fw@strlen•de>,
netfilter-devel@vger•kernel.org, netdev <netdev@vger•kernel.org>,
Eric Dumazet <edumazet@google•com>,
syzbot <syzkaller@googlegroups•com>
Subject: Re: [PATCH nf] netfilter: conntrack: serialize hash resizes and cleanups
Date: Tue, 21 Sep 2021 03:51:41 +0200 [thread overview]
Message-ID: <YUk6rWNxqMi37N7K@salvia> (raw)
In-Reply-To: <20210917221556.1162846-1-eric.dumazet@gmail.com>
On Fri, Sep 17, 2021 at 03:15:56PM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google•com>
>
> Syzbot was able to trigger the following warning [1]
>
> No repro found by syzbot yet but I was able to trigger similar issue
> by having 2 scripts running in parallel, changing conntrack hash sizes,
> and:
>
> for j in `seq 1 1000` ; do unshare -n /bin/true >/dev/null ; done
>
> It would take more than 5 minutes for net_namespace structures
> to be cleaned up.
>
> This is because nf_ct_iterate_cleanup() has to restart everytime
> a resize happened.
>
> By adding a mutex, we can serialize hash resizes and cleanups
> and also make get_next_corpse() faster by skipping over empty
> buckets.
>
> Even without resizes in the picture, this patch considerably
> speeds up network namespace dismantles.
Applied, thanks.
prev parent reply other threads:[~2021-09-21 1:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-17 22:15 [PATCH nf] netfilter: conntrack: serialize hash resizes and cleanups Eric Dumazet
2021-09-19 9:20 ` Florian Westphal
2021-09-21 1:51 ` Pablo Neira Ayuso [this message]
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