From mboxrd@z Thu Jan  1 00:00:00 1970
From: Martin KaFai Lau <kafai@fb.com>
Subject: Re: kernel warning in tcp_fragment
Date: Wed, 12 Aug 2015 20:45:28 -0700
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Cc: Neal Cardwell <ncardwell@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Netdev <netdev@vger.kernel.org>,
	David Miller <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	James Morris <jmorris@namei.org>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Patrick McHardy <kaber@trash.net>,
	FB Kernel Team <kernel-team@fb.com>
To: Jovi Zhangwei <jovi@cloudflare.com>
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On Mon, Aug 10, 2015 at 02:35:37PM -0400, Neal Cardwell wrote:
> On Mon, Aug 10, 2015 at 2:10 PM, Jovi Zhangwei <jovi@cloudflare.com> wrote:
> >
> > Ping?
> >
> > We saw a lot of this warnings in our production system. It would be
> > great appreciate if someone can give us the fix on this warnings. :)
> 
> What is your net.ipv4.tcp_mtu_probing setting? If 1, have you tried
> setting it to 0? 

Hi Jovi, If setting net.ipv4.tcp_mtu_probing=0 helps, can you give the
patch we posted earlier a try: https://patchwork.ozlabs.org/patch/481609/
It is the same patch that I pointed out earlier. You can click
on the download link.

We are currently using a similar patch while keeping net.ipv4.tcp_mtu_probing=1.

Thanks,
--Martin