netdev - Re: TCP connection closed without FIN or RST

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Date:   Fri, 03 Nov 2017 14:33:37 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Vitaly Davidovich <vitalyd@...il.com>
Cc:     netdev <netdev@...r.kernel.org>
Subject: Re: TCP connection closed without FIN or RST

On Fri, 2017-11-03 at 14:28 -0400, Vitaly Davidovich wrote:

> So Eric, while I still have your interest here (although I know it's
> waning :)), any code pointers to where I might look to see if a
> specific small-ish rcv buf size may interact poorly with the rest of
> the stack? Is it possible some buffer was starved in the client stack
> which prevented it from sending any segments to the server? Maybe the
> incoming retrans were actually dropped somewhere in the ingress pkt
> processing and so the stack doesn't know it needs to react to
> something? Pulling at straws here but clearly the recv buf size, and a
> somewhat small one at that, has some play.
> 
> I checked dmesg (just in case something would pop up there) but didn't
> observe any warnings or anything interesting.

I believe you could reproduce the issue with packetdrill.

If you can provide a packetdrill file demonstrating the issue, that
would be awesome ;)