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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 702D6C388F7 for ; Thu, 22 Oct 2020 14:40:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A82C24182 for ; Thu, 22 Oct 2020 14:40:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="AMq0UAvn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2900999AbgJVOkM (ORCPT ); Thu, 22 Oct 2020 10:40:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2900978AbgJVOkL (ORCPT ); Thu, 22 Oct 2020 10:40:11 -0400 Received: from mail-ua1-x941.google.com (mail-ua1-x941.google.com [IPv6:2607:f8b0:4864:20::941]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4824BC0613CE for ; Thu, 22 Oct 2020 07:40:11 -0700 (PDT) Received: by mail-ua1-x941.google.com with SMTP id x26so529195uau.0 for ; Thu, 22 Oct 2020 07:40:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=vt5F6KjNkmlnBeWxGhnHoc3bQg0jZFtZbaw7129oA3s=; b=AMq0UAvnkW9myH4lLhbH+zoRftq1BDpywSbP4m1vMOrJY5t7cbM/YtIkVDUP5xeT0J 1KbN8Gi3+0lJt8qnnh+DMvPen9E1qzHSpLp58y24FLTKL+q86DTqgfZM0SOXoBHsmDpT hdoke0YqHf1CWFAsGvIuYcHYGOf4PIsdV3ISB0CbQCzbxfZRO6xw6dmlIIXvpScLOZdA FHTX+1EMkn3B4clOVJTH8ifvnDkYotwKqJbOA8/evkWVEU/As3rvDJaGcw19xPMUBiPa UnIvKouiJ+bgOR4qztjhYxyt7JZ1LE9CRmI52bt++aNtmanfU1yjfhjQuOOTsWd3z8J8 9JeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vt5F6KjNkmlnBeWxGhnHoc3bQg0jZFtZbaw7129oA3s=; b=GGSMGZp3ePc0If8TX09bMGU2mqDR970FNvdJ6PeQppYOU2cSV/tIXZTUOj4lc6ooiO KSY6AJc93uj6mdFmI9iy1OV03JUtnXzs+6VE0UIN88SMu+ZNbdekJqMqFUaPgj7kanYK 1mkUECOojvNCsAl4UrjD4IEfHo78l2rLhp9ApSACMqp245wAe4STKsPn+Kqp1nBFSu+z u7K4V4Sob7SCNuv3ALRJOxmApra2QhUfkGh+KOQRAVKk92WFRzEhiUP0v38p7R0TZfer OjcV1gEkMBBKTwSncxsbvOOBpgRkLKyKAAZ4zLwHJy51Ep4fTrb6oJceTGhmtoYiCgVw 056Q== X-Gm-Message-State: AOAM532t1WLYuCZWyxZ9jD3vjsBmEJvrjKzZIeFnJXxHQDkUGkxgKRVp 2J/qSqavt+W/tXHJ3nkqpovs6LJFGE4ekQlcWAWGE+mWOeS4fg== X-Google-Smtp-Source: ABdhPJxpQwR1l/zSQXGR1FZ+gBuONWjh6daQsMmfwnlDyM+b1IPMRUdELKqO7YXucWygIf2luKJLzPX4iaqSBD6xaqo= X-Received: by 2002:ab0:5b55:: with SMTP id v21mr1521733uae.65.1603377609017; Thu, 22 Oct 2020 07:40:09 -0700 (PDT) MIME-Version: 1.0 References: <87eelz4abk.fsf@marvin.dmesg.gr> <87blh33zr7.fsf@marvin.dmesg.gr> <878sc63y8j.fsf@marvin.dmesg.gr> <87eelqs9za.fsf@marvin.dmesg.gr> In-Reply-To: <87eelqs9za.fsf@marvin.dmesg.gr> From: Neal Cardwell Date: Thu, 22 Oct 2020 10:39:51 -0400 Message-ID: Subject: Re: TCP sender stuck in persist despite peer advertising non-zero window To: Apollon Oikonomopoulos Cc: Yuchung Cheng , Netdev , Eric Dumazet , Soheil Hassas Yeganeh Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Oct 22, 2020 at 8:47 AM Apollon Oikonomopoulos wrote: > > Apollon Oikonomopoulos writes: > > We are now running the patched kernel on the machines involved. I want > > to give it some time just to be sure, so I'll get back to you by > > Thursday if everything goes well. > > It has been almost a week and we have had zero hangs in 60 rsync runs, > so I guess we can call it fixed. At the same time we didn't notice any > ill side-effects. In the unlikely event it hangs again, I will let you > know. Great. Many thanks for your testing and thorough analysis! I agree that it's a little surprising that this bug would be there for so long (looks like since Linux v2.1.8 in Nov 1996), but I also agree with your analysis about why this might be so. I have posted the proposed patch here: https://patchwork.ozlabs.org/project/netdev/patch/20201022143331.1887495-1-ncardwell.kernel@gmail.com/ best, neal