From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: Fwd: Re: GRO issue with kernel 3.4.94 (icmp fragmentation needed) Date: Mon, 4 Aug 2014 21:52:54 -0700 Message-ID: <20140805045254.GA31762@kroah.com> References: <1836813.giEndUKvmp@storm> <20140730002255.GA16109@kroah.com> <20140730063703.GA24753@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Thomas Jarosch , netdev@vger.kernel.org To: Florian Westphal Return-path: Received: from out1-smtp.messagingengine.com ([66.111.4.25]:41353 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752121AbaHEEx2 (ORCPT ); Tue, 5 Aug 2014 00:53:28 -0400 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by gateway1.nyi.internal (Postfix) with ESMTP id 2A13C22777 for ; Tue, 5 Aug 2014 00:53:25 -0400 (EDT) Content-Disposition: inline In-Reply-To: <20140730063703.GA24753@breakpoint.cc> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jul 30, 2014 at 08:37:03AM +0200, Florian Westphal wrote: > Greg KH wrote: > > [ CCing David. If I understood him correctly, he recommended to revert > the GRO forwarding changes for oldstable 3.2/3.4.y series. I second > this. But see below for answer to your question ] > > > On Fri, Jul 11, 2014 at 05:12:55PM +0200, Thomas Jarosch wrote: > > > Subject: Re: GRO issue with kernel 3.4.94 (icmp fragmentation needed) > > > Date: Friday, 27. June 2014, 11:05:25 > > > From: Florian Westphal > > > To: jungwon park > > > CC: netdev@vger.kernel.org > > > > > > jungwon park wrote: > > > > When using the linux router is turned on GRO, router send the > > > 'fragmentation > > > > needed' packets to the sender. > > > > > > Indeed 8-( > > > > > > > When I turned off GRO, the router operate normally, and there is no > > > problem. > > > > and with 3.4.91 kernel, the router has no problem. > > > > > > > > I doubt 'ipv4: ip_forward: fix inverted local_df test' patch. > > > > (http://patchwork.ozlabs.org/patch/345509/) > > > > When I revert this patch, the router has no problem. > > > > > > Can you please cherry-pick following patch on top of vanilla 3.4.92? > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=21d1196a35f5686c4323e42a62fdb4b23b0ab4a3 > > > > > > commit 21d1196a35f5686c4323e42a62fdb4b23b0ab4a3 > > > Author: Eric Dumazet > > > ipv4: set transport header earlier > > > > > > I think that should fix this bug, it should apply cleanly on top of > > > 3.4.y tree. > > > > > > [ patch is in 3.11, also backported to 3.10.y tree ] > > > > > > The problem is that, when dealing with GRO packets, we try to determine > > > the size of the individual packets. To do this, we rely on the > > > transport header. > > > > > > Unfortunately the transport header is not set for the forward path in 3.4, > > > so we look at the network header instead. > > > > Why would this patch matter, as commit 45f00f99d6e, which this patch > > fixes, is not in the 3.4-stable tree at all. > > It helps, because I underestimated the changes the network stacki went through > since 3.2 and 3.4 had been released. > > The GRO forwarding change, (fe6cc55f3a9a053482a76f5a6b2257cee51b4663 > upstream) depends on having the transport header available in the > forward path, and not just in the input/local delivery path. > > The Patch from Eric Dumazet that I referenced above made this change. > So, while its unrelated to the GRO forward patch, it is a dependency. > > However, given the numerous problems reported with the GRO changes in > older stable kernels I think the commit > 29a3cd46644ec8098dbe1c12f89643b5c11831a9 in 3.4.y should be reverted. > > [ In 3.2.y its caa5344994778a2b4725b2d75c74430f76925e4a ] > > > Also, network stable patches need to go through the network maintainer, > > not me directly. > > Greg, is above explanation enough for you to revert? Yup, that's good enough, I had to do the revert by hand, a verification would be nice to have. thanks, greg k-h