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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 80E56C74A35 for ; Wed, 10 Jul 2019 19:10:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DBCD20651 for ; Wed, 10 Jul 2019 19:10:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728140AbfGJTKD (ORCPT ); Wed, 10 Jul 2019 15:10:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41556 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727612AbfGJTKC (ORCPT ); Wed, 10 Jul 2019 15:10:02 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B98E230BC56E; Wed, 10 Jul 2019 19:10:02 +0000 (UTC) Received: from elisabeth (ovpn-200-17.brq.redhat.com [10.40.200.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 19BB38847E; Wed, 10 Jul 2019 19:09:59 +0000 (UTC) Date: Wed, 10 Jul 2019 21:09:54 +0200 From: Stefano Brivio To: Jan Szewczyk Cc: David Ahern , "davem@davemloft.net" , "netdev@vger.kernel.org" , Wei Wang , Martin KaFai Lau , Eric Dumazet Subject: Re: Question about linux kernel commit: "net/ipv6: move metrics from dst to rt6_info" Message-ID: <20190710210954.530d72a5@elisabeth> In-Reply-To: References: Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Wed, 10 Jul 2019 19:10:02 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Jan, On Wed, 10 Jul 2019 12:59:41 +0000 Jan Szewczyk wrote: > Hi! > I digged up a little further and maybe it's not a problem with MTU > itself. I checked every entry I get from RTM_GETROUTE netlink message > and after triggering "too big packet" by pinging ipv6address I get > exactly the same messages on 4.12 and 4.18, except that the one with > that pinged ipv6address is missing on 4.18 at all. What is weird - > it's visible when running "ip route get to ipv6address". Do you know > why there is a mismatch there? If I understand you correctly, an implementation equivalent to 'ip -6 route list show' (using the NLM_F_DUMP flag) won't show the so-called route exception, while 'ip -6 route get' shows it. If that's the case: that was broken by commit 2b760fcf5cfb ("ipv6: hook up exception table to store dst cache") that landed in 4.15, and fixed by net-next commit 1e47b4837f3b ("ipv6: Dump route exceptions if requested"). For more details, see the log of this commit itself. -- Stefano