From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1757221AbcAJO5o (ORCPT <rfc822;w@1wt.eu>);
	Sun, 10 Jan 2016 09:57:44 -0500
Received: from vulcan.natalenko.name ([104.207.131.136]:15050 "EHLO
	vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1755824AbcAJO5n convert rfc822-to-8bit (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sun, 10 Jan 2016 09:57:43 -0500
DMARC-Filter: OpenDMARC Filter v1.3.1 vulcan.natalenko.name B183C78B63
Authentication-Results: vulcan.natalenko.name; dmarc=none header.from=natalenko.name
From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>, netdev <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Patrick McHardy <kaber@trash.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        James Morris <jmorris@namei.org>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        "David S. Miller" <davem@davemloft.net>
Subject: Re: [REGRESSION] tcp/ipv4: kernel panic because of (possible) division by zero
Date: Sun, 10 Jan 2016 16:57:40 +0200
Message-ID: <4496498.SgxPQx9et6@spock>
User-Agent: KMail/5.1 (Linux/4.3.0-pf3; KDE/5.17.0; x86_64; ; )
In-Reply-To: <CADVnQykvDhCrCuFR0MCiEvD7DUbf+ZVBOysa1iWSE6-FydzqYQ@mail.gmail.com>
References: <26396443.iDTTxgChSj@spock> <CADVnQy=S62KoQL7thY73Kb=1Qd60drvOHJhE8UwH9qzPFOadEg@mail.gmail.com> <CADVnQykvDhCrCuFR0MCiEvD7DUbf+ZVBOysa1iWSE6-FydzqYQ@mail.gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8BIT
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Yes, this is my next step. Then I'll try to move from YeAH.

On неділя, 10 січня 2016 р. 09:54:16 EET Neal Cardwell wrote:
> On Sun, Jan 10, 2016 at 9:48 AM, Neal Cardwell <ncardwell@google.com> wrote:
> > On Sun, Jan 10, 2016 at 5:23 AM, Oleksandr Natalenko
> > 
> > <oleksandr@natalenko.name> wrote:
> >> With the patch queued for upstream and ECN enabled I get WARN_ON_ONCE()
> >> triggered. Here is the stacktrace:
> >> 
> >> https://gist.github.com/89203e77bfcb051f269a
> >> 
> >> It seems that tp->prior_cwnd is zero.
> > 
> > Hmm. Interesting. Can you please confirm that you are using the cubic
> > congestion control module?
> 
> Would you be able to do an experiment where you reboot, and then
> disable ECN upon startup, and then see if the warning still shows up
> without ECN?
> 
> thanks,
> neal