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=-3.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 31D67C4346E for ; Sun, 27 Sep 2020 16:10:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E257F20B80 for ; Sun, 27 Sep 2020 16:10:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726360AbgI0QKx (ORCPT ); Sun, 27 Sep 2020 12:10:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbgI0QKx (ORCPT ); Sun, 27 Sep 2020 12:10:53 -0400 Received: from mails.bitsofnetworks.org (mails.bitsofnetworks.org [IPv6:2001:912:1800:ff::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 659EFC0613CE for ; Sun, 27 Sep 2020 09:10:53 -0700 (PDT) Received: from [2001:912:1800::ac1] (helo=fedic) by mails.bitsofnetworks.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1kMZGE-0000aj-Fn; Sun, 27 Sep 2020 18:10:50 +0200 Date: Sun, 27 Sep 2020 18:10:31 +0200 From: Baptiste Jonglez To: David Ahern Cc: Alarig Le Lay , netdev@vger.kernel.org, jack@basilfillan.uk, Vincent Bernat , Oliver Subject: Re: IPv6 regression introduced by commit 3b6761d18bc11f2af2a6fc494e9026d39593f22c Message-ID: <20200927161031.GB471334@fedic> References: <20200305081747.tullbdlj66yf3w2w@mew.swordarmor.fr> <20200927153552.GA471334@fedic> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="KFztAG8eRSV9hGtP" Content-Disposition: inline In-Reply-To: <20200927153552.GA471334@fedic> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --KFztAG8eRSV9hGtP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On 27-09-20, Baptiste Jonglez wrote: > 1) failing IPv6 neighbours, what Alarig reported. We are seeing this > on a full-view BGP router with rather low amount of IPv6 traffic > (around 10-20 Mbps) Ok, I found a quick way to reproduce this issue: # for net in {1..9999}; do ip -6 route add 2001:db8:ffff:${net}::/64 via fe80::4242 dev lo; done and then: # for net in {1..9999}; do ping -c1 2001:db8:ffff:${net}::1; done This quickly gets to a situation where ping fails early with: ping: connect: Network is unreachable At this point, IPv6 connectivity is broken. The kernel is no longer replying to IPv6 neighbor solicitation from other hosts on local networks. When this happens, the "fib_rt_alloc" field from /proc/net/rt6_stats is roughly equal to net.ipv6.route.max_size (a bit more in my tests). Interestingly, the system appears to stay in this broken state indefinitely, even without trying to send new IPv6 traffic. The fib_rt_alloc statistics does not decrease. Hopes this helps, Baptiste --KFztAG8eRSV9hGtP Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEjVflzZuxNlVFbt5QvgHsIqBOLkYFAl9wuXcACgkQvgHsIqBO LkaV1BAAuBHunjV8fLjg88sr2zh83EpLP2OX0VwbGiUOFtoVxAY2ucZY5tzH4y55 O6v2S9YMMpcUXo+dkClzbxCs7VVRaFeZLyltAAbqCgXLV+z//vkBuSd4TLe/vy/T El4YwGa4A0oKGNcXDFXtfsKuxX9AUYiGZt7ffy+2vPtmkDiTgW/qRGHApRLFlaXy 3497E4z5E8bOQeU6QLZD4P0IRmwATvluSGULQ8mtDx933Nz7WfqdM46vuRZjeB/x vBX4O5hqQWY09f3zO4o7gzrWp8MAMyUNpRPxfHblM9F92exBHdoIKcFJ0AEmRrJ+ 8/fLf3Ydob5JVwFiaWFnZqn1lBA+Bdae1zKLTRgjtrslzgzr67ie9P4vf03aFsNj QAAKB4Yvtha+qvDeRMUNjWNXecJDrbxgWl4pQAjJ0z0JPWh+V1n/ZuRZ/PIqDDMU utgwkVU2y+eBj5mrt8UeNGSO31qWyO3S3pQKyXzynelEOFnwGy3BjaJXYkFWr6M8 XpWrUtuZLYF4c3pHvLL0GaKyjp3BOvE7u+io6TdZuAqN5idnlv1vUVx5R5+bC0Cf nygAcco08zKBILSW7YlE/ss7UCsGez6QUXv8grNcs1h8FbDVFzBJ1LtLOwQP0CrW omnHnL5MQLuP5HyNHY8mo4wzN3kc2SAT40PYegyg5d4f6Xuycl8= =63Cg -----END PGP SIGNATURE----- --KFztAG8eRSV9hGtP--