From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8D9E3219E8 for ; Wed, 27 May 2026 23:07:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779923238; cv=none; b=e7X53ehFuVdhY9qYHwv9lzniquC3TnSn3AYKkyPQ4i7HzKH+D5RL4R7DvGn2tTAlhmBltNnJDx7Mruwm+afoHPN0nnrNbhqhoZRQ+E5tugyH+imzalCHaI+cQv8s4TdZjCoya12eRhstEbyMCyx8vZk1LTMfDdGuiJTIbyICzps= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779923238; c=relaxed/simple; bh=W6obAhP6PCYR5rhunNCnMBDk3RscY52AknMeg6sxGyA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UVt8lbQDcT/yLaiG8je/M5JU3vwROTTLPXiDuQgcCLhhOZ8UaLYODUSENCswTpvSAK1L7D7YdVIx4khrFo28i1uUufLWQjyiEnnpeBfK/5zeI+UIivswTeN3i6j4YdrQPtRD620PHTqfFXjN9r3LOwnABOs9WrjPiO8sHey84wk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CgjTHk0S; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CgjTHk0S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47D011F000E9; Wed, 27 May 2026 23:07:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779923237; bh=g88PR7qF3idSr7KQdx9j2J5RWimgQFtsq87ECfgIZs8=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=CgjTHk0ScNaGILOAqahyeIfWxgB9waARhGzKkarQseznQOGZTJMqoEonV6ZUGkQVC cSb/C2mKR5IOXVgOBS7+TkyLrQ/wRuJyaUF29AHcY6hoLAwDKHwg5MY7miVdy1M1C9 RcIaHhCSST7zpuhA0LBzH1tqE4Pu2xNdxwhvCeV29I4/Se121dp/JGnS6fvyz0Dro2 CFdaVdfqxImsP4/rmxz4TfYUakK3/FQ2qLnFwr5vvSWPqbQ0qo9r1Fob7geQDlI2ku e1ua3aQFZ0tmbw2sfxdXagYUIcWIoMOd4nLo1zMDzMcoHPI0ClGWySOPKaDv2TXTYB X5xR0Il5fv1ZA== Date: Wed, 27 May 2026 16:07:16 -0700 From: Jakub Kicinski To: Fernando Fernandez Mancera Cc: netdev@vger.kernel.org, Yumei Huang , Ido Schimmel Subject: Re: Problem with IPv6 privacy addresses in 7.0 Message-ID: <20260527160716.147e240f@kernel.org> In-Reply-To: <675083b4-e015-4ff3-836c-798e0a971194@suse.de> References: <20260521135310.GC977@cmadams.net> <20260526175743.1f2c3761@kernel.org> <20260527010641.GA21073@cmadams.net> <20260526183122.348e44e7@kernel.org> <20260527215135.GB16443@cmadams.net> <675083b4-e015-4ff3-836c-798e0a971194@suse.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 27 May 2026 23:59:47 +0200 Fernando Fernandez Mancera wrote: > On 5/27/26 11:51 PM, Chris Adams wrote: > > Once upon a time, Jakub Kicinski said: > >> Sounds plausible, pretty sure we knew this commit was risky to begin > >> with, but we had no direct proof that it'd break real life users. > >> > >> Revert is the right course of action here. Would you be willing/able > >> to send the revert with your problem description and a Fixes tag > >> pointing to the reverted commit? > > > > I did want to add a little more test note: > > > > It's definitely an interaction with NetworkManager. If I stop NM and > > run my VM start/stop test, nothing unexpected happens after. If NM is > > running and I do my VM test, when the next router advertisement is > > received, NM replaces the privacy addresses. > > > > As someone that is experienced in NetworkManager, I can confirm it is > related. NetworkManager is querying the IPv6 address and when the > connection is configured with ipv6.ip6-privacy=2 (prefer-temp-addr), > NetworkManager creates a route to make the system use the temporary > address for outgoing connections by default. > > If the order is messed up, the address picked will likely be too. One > could argue that this is partially fault of NetworkManager and that it > should check the timestamps or preferred times rather than order.. but > well, the rule is "do not break userspace". Right, plus the justification for the change wasn't very strong in the first place. My internal compass is still pointing towards a revert. > I hope this clarifies things.