From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin LaHaise Subject: Re: 3.6.10 tcp crash - net/ipv4/tcp.c:1667 & tcp.c:1655 Date: Mon, 17 Dec 2012 14:52:13 -0500 Message-ID: <20121217195212.GI22452@kvack.org> References: <20121217174145.GH22452@kvack.org> <1355772853.9380.10.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from kanga.kvack.org ([205.233.56.17]:58525 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752628Ab2LQTwO (ORCPT ); Mon, 17 Dec 2012 14:52:14 -0500 Content-Disposition: inline In-Reply-To: <1355772853.9380.10.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Dec 17, 2012 at 11:34:13AM -0800, Eric Dumazet wrote: > On Mon, 2012-12-17 at 12:41 -0500, Benjamin LaHaise wrote: > > Hi folks, > > > > I just hit the following crash with Fedora's 3.6.10-2.fc17 kernel. I don't > > have time to debug this myself at the moment, but can certainly test patches > > or provide more info as needed. I wasn't doing anything unusual at the time, > > just reading email/web browsing. I believe the network driver in use was > > ipheth for tethering to an iPhone 4S over USB (the other driver being used > > intermittently on this laptop is iwlwifi). Any ideas? > > I see nothing really wrong on ipheth side. > > I would be nice to know which driver is really in use when you have a > panic, as its probably a driver issue. I double checked the logs, and the wifi was disabled at the time (~30 minutes beforehand), so it had to be ipheth. The warnings were the last thing that made it to disk before the machine hung hard, so there may have been a more serious crash after the warning that did not get logged. One thing I have observed with tethering is that the MTU handling is munged by the network in interesting ways. Although the device claims to be ethernet with a 1500 byte MTU, a 'ping -s' works only up to 996 (with no effect trying the various -M options). A number of website are broken by this, as the network doesn't seem to send ICMP frag needed errors to my tethered host (but I haven't traced this behaviour from both ends yet). Things do work for 1500 byte packets to the gateway IP, but that seems to be local to the phone. -ben -- "Thought is the essence of where you are now."