From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9147EC433E0 for ; Mon, 3 Aug 2020 13:32:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F044206DA for ; Mon, 3 Aug 2020 13:32:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PwZ8mh2N" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726813AbgHCNcx (ORCPT ); Mon, 3 Aug 2020 09:32:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726398AbgHCNcw (ORCPT ); Mon, 3 Aug 2020 09:32:52 -0400 Received: from mail-qt1-x832.google.com (mail-qt1-x832.google.com [IPv6:2607:f8b0:4864:20::832]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D828C06174A for ; Mon, 3 Aug 2020 06:32:52 -0700 (PDT) Received: by mail-qt1-x832.google.com with SMTP id w9so28135335qts.6 for ; Mon, 03 Aug 2020 06:32:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=TrzfKFWrqonVAodS9SHcefk8HofmhSvW71qt8kR88FA=; b=PwZ8mh2NvGUVvgYTYkJ1ZgFP7aMOSWf93VXYi07/AFssOSlfZHl3V+387uJVUE4mtN P4RZRSV2EbrpqvbIcLu4ZZWDj8LSUqZEjFwBFU0VwqSiVyKxQwWhYXXov7fy+nDQj/nP /U2bJHcA0fMk3/1E7YOVFoMvaXk5UKaqwZWKK8XZHI6qDdDak8Nbsh3/zMcc3ABVSh8D 2TlBkZYGIBYZjXcMeX6aSx+/NST8gS0QB2Tsi7GNwdl20UnOUvVhY5qkHFRrxR+dNmq4 6R2UoQ+nVIzChO64821fmEEBdjszs+U9w4tLNUQkxZBgljhiJw83lZprlWquW9YfdEmu hPpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TrzfKFWrqonVAodS9SHcefk8HofmhSvW71qt8kR88FA=; b=kLtpPvcCLGDF86iNIRVP1sHL5fxSHhQVFGXBk/ai8DuytgIgweJWVtd+mT3Swk3VBb CxnLapD1cHGi+OmjAuNs3tucLUE/CSQTSP5q97cf8H1FOj19EdnRJBY+DtMqyzYJ3iAV 3Mw5/4QjcpPLDWE4AD3BV63Qytxp/nKvKAuKL8xjvuRRf+87naDhEEXzpsZmKIuavT+2 8NIDubDhhWCM9eh3yN8zNwdjyBXL0E4F95iNBmTBh0MvZKavvzdnyTDTFwK4DX10wJK8 d1ZOlY94J3i4f8l5nUYziAnqcMp2WiAN3pOvPNca9Brj08aYazS8o9v0aUDu56eBkSRo fJsQ== X-Gm-Message-State: AOAM5322VKT5rlB+8ULBmTMJ5fDw1WU2aCE1fS2Ln5uCPNDja8sqMFbX dl85QRFhP6B6IMafdgLWv+tbF8DI X-Google-Smtp-Source: ABdhPJws3pFjuZQnabnelWM/Sx/yQcjddTNKabirVknl60qkP44K0IvsjNNPe1g9XhOVazhj2QODuQ== X-Received: by 2002:ac8:47c8:: with SMTP id d8mr15494022qtr.32.1596461571003; Mon, 03 Aug 2020 06:32:51 -0700 (PDT) Received: from ?IPv6:2601:284:8202:10b0:989f:23de:f9a0:6da? ([2601:284:8202:10b0:989f:23de:f9a0:6da]) by smtp.googlemail.com with ESMTPSA id q7sm4067965qkf.35.2020.08.03.06.32.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Aug 2020 06:32:49 -0700 (PDT) Subject: Re: PMTUD broken inside network namespace with multipath routing To: mastertheknife , netdev@vger.kernel.org References: From: David Ahern Message-ID: Date: Mon, 3 Aug 2020 07:32:48 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 8/3/20 5:14 AM, mastertheknife wrote: > What seems to be happening, is that when multipath routing is used > inside LXC (or any network namespace), the kernel doesn't generate a > routing exception to force the lower MTU. > I believe this is a bug inside the kernel. > Known problem. Original message can take path 1 and ICMP message can path 2. The exception is then created on the wrong path.