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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 37445C43382 for ; Thu, 27 Sep 2018 02:18:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D559C2156E for ; Thu, 27 Sep 2018 02:18:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hWpmxmQq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D559C2156E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727258AbeI0IeZ (ORCPT ); Thu, 27 Sep 2018 04:34:25 -0400 Received: from mail-pg1-f175.google.com ([209.85.215.175]:39687 "EHLO mail-pg1-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726953AbeI0IeZ (ORCPT ); Thu, 27 Sep 2018 04:34:25 -0400 Received: by mail-pg1-f175.google.com with SMTP id 85-v6so712205pge.6; Wed, 26 Sep 2018 19:18:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=A90Lp2W6H1+QKdsi/tGZOMLHo6szgWaNW4589vJxLIU=; b=hWpmxmQqMq//uMr1RRZQxPLg13DaJvapc2iL6jBFg+FZsF1MYDtiXiKRA993sE77fz BX9k7v9lAum8LM3OytcNSj9/AvcngWEXW9hNjzm7qtt3oSZ7cjIdtgS2FRfE2MeRU25E TmgiT/B6b/a2YbpeBQl2Mf/zJrLTcQl7TTSwF6b6wotPNSS+Fu3B9AaFcy80UPK2Kvy7 RzmSBx15y0l5lyTaMhNbScWWfdliPGvlvMBZX5hEX2EVF2CCoNKOp/pQQcfqMe/hIu3I 3pIWHdf65rUbMVhCBeqRXIPkMzPawKi+dDRrDw6yglMM2+nYsqHrmQhDKuh8BCfbiFGm bzxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=A90Lp2W6H1+QKdsi/tGZOMLHo6szgWaNW4589vJxLIU=; b=qQlC+rJ5HCz+WmZJNqiKPgq9BwjLY2PPRa5P0ELweP5XhKYB2mqW1aaRO6Ib7hDWhO XlSi72K/8J2YqoR0dzgPhOy6b8vY1ew8vpFsqujatk9OYJKt8NSfYKd1EPFg2rlzDSqx KbRLFPn/8QgBw9ZfefkkvMfCunc0JIykYWaRluqMEK4IbjSvBYxiY+BCYaGHwUMo6FSe UIaDAUWP5LMEH1mJOYRjIqtoeuTZ82u+q3TOewtZndyk87lB5kJAzvEVCHgJLOH7aYn2 dRPLmNTSJ/66oSLrgyx0HWTSPPDfEjHvp2pA0STX11mcFOB8iyw+OoSJa+h8cUdX92ds dnDg== X-Gm-Message-State: ABuFfojOY/k9QOq3BZnbDABFj5zhAE9Tpq35HM21qqkh/kmYjnDm6s+l rJc5Opgcr5OhIQuebgtycdc= X-Google-Smtp-Source: ACcGV606d2p3BewOLi5iJqWKh7rYxkas3Cgn6BPfd2hazvev7WDUEE7+EirUHOD9P4gD/Er0kIPs/w== X-Received: by 2002:a17:902:6909:: with SMTP id j9-v6mr8512247plk.196.1538014710485; Wed, 26 Sep 2018 19:18:30 -0700 (PDT) Received: from [192.168.86.235] (c-67-180-167-114.hsd1.ca.comcast.net. [67.180.167.114]) by smtp.gmail.com with ESMTPSA id 1-v6sm604434pfm.145.2018.09.26.19.18.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Sep 2018 19:18:29 -0700 (PDT) Subject: Re: nfs+tcp boot failures on linuxnext-20180924 from switch tcp_clock_ns to CLOCK_TAI To: Leonard Crestez , "sfr@canb.auug.org.au" , "davem@davemloft.net" , "edumazet@google.com" Cc: "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-next@vger.kernel.org" , Jesus Sanchez-Palencia , Vinicius Costa Gomes References: <30e76d01dd08c2d9127072ad28c5a99afc5daabf.camel@nxp.com> From: Eric Dumazet Message-ID: <2185d09d-90e1-81ef-7c7f-346eeb951bf4@gmail.com> Date: Wed, 26 Sep 2018 19:18:28 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <30e76d01dd08c2d9127072ad28c5a99afc5daabf.camel@nxp.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/26/2018 06:15 PM, Leonard Crestez wrote: > Hello, > > It seems that after commit 72b0094f9182 ("tcp: switch tcp_clock_ns() to > CLOCK_TAI base") some systems that use nfs over tcp fail to boot. The > last line printed in the log is from systemd: > > [ 7.232579] systemd[1]: System time before build time, advancing clock. > > Superficially it looks like very large clock discontinuities now break > TCP. Maybe boottime could avoid such issues? > > I didn't find similar reports anywhere else. The machines I’m seeing > this are all 32bit arm imx (this shouldn’t matter) and it seems their > RTC isn’t properly setup so they boot with realtime set to unix zero, > then a ~50 years jump happens when systemd starts up. This is the > likely trigger for this issue. > Thanks for the report. It is annoying, because SCM_TXTIME and net/sched/sch_etf.c are using CLOCK_TAI, so it means that if we convert TCP (and net/sched/sch_fq.c) back to ktime_get_ns(), we will have to differentiate in skbs the clock base. This has been discussed in the past (When ETF was merged in 4.19) and we chose to use a common clock base.