linux-kernel - Re: [PATCH] tproxy: nf_tproxy_assign

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Date:	Wed, 14 Jul 2010 02:56:18 -0400
From:	Bill Fink <billfink@...dspring.com>
To:	Felipe W Damasio <felipewd@...il.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>, Avi Kivity <avi@...hat.com>,
	David Miller <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	linux-kernel@...r.kernel.org, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] tproxy: nf_tproxy_assign_sock() can handle tw sockets

On Wed, 14 Jul 2010, Felipe W Damasio wrote:

> Hi,
> 
> 2010/7/14 Eric Dumazet <eric.dumazet@...il.com>:
> >> I can, but my bosses will kick my ass if I bring down the ISP again :)
> >
> > I have no guarantee at all, even if we find the bug.
> 
> Ok :-)
> 
> >> If you think it's the only way to find the problem I'll tell them that
> >> I need to do it. In this case, please tell me what other config
> >> options/tools I can use to get as much info as possible...since I'll
> >> probably be able to test this only once more on the production
> >> environment for debugging purposes.
> >
> > You really should try to setup a lab to trigger the bug, and not doing
> > experiments on production :)
> 
> Right, I'm trying.
> 
> The thing is: The ISP is a 200Mbps network with 10,000 users. The
> first time it took around 2 minutes to trigger the bug. The second
> time it took around 17 minutes.
> 
> So I *think* it's some TCP flag with some weird content...but I can't
> find out what it is so I can trigger it on the lab.
> 
> So my only guess is to enable every possible debug flag I can think of
> to track the bug down on the production environment. Any hints here
> would be appreciated :)

Is it possible for you to mirror the production traffic to another
port, and then do a tcpdump capture to a series of files, so that
you might possibly be able to correlate the kernel crash to the
actual packets on the wire (and the Invalid Request squid errors)?
Just a suggestion.

						-Bill
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