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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 69BFEC4338F for ; Mon, 9 Aug 2021 00:28:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4147860F42 for ; Mon, 9 Aug 2021 00:28:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232435AbhHIA3R (ORCPT ); Sun, 8 Aug 2021 20:29:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229903AbhHIA3R (ORCPT ); Sun, 8 Aug 2021 20:29:17 -0400 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B96AAC061760 for ; Sun, 8 Aug 2021 17:28:56 -0700 (PDT) Received: by mail-pl1-x62c.google.com with SMTP id j3so14564403plx.4 for ; Sun, 08 Aug 2021 17:28:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=hTQAbzTf9ULU0kxq5RVe3UvFkDJIkSogU54CcY+eeF4=; b=bfjqJjykzDBi01hxfPK2tUKnrh5Wk8kNPx1u7oZNjR/yJDSid8ddjwFPy4kjls6Vio pvPwcbpMikv/y5GU91WO4zpdug4yzbXUar+QXqPWTwuyb4rlGK1W6kGBR1R1m8yl2PrR Vm2sQsiUlxLgjynC927jxSK3K/Gci5R9vAB2VksoKQLEyqepAyBuuZN0o6Wso9yRL0Ut wBkXcmA/XYxVFDcfuQlBI7PHZgQ5iieh7Ooap/OvWpeGwgXmsOfJ2No9grLBz9jWcM6c O8zCP/wty7eb3pHDJtcT/rav2yQLk+eM9g1LCn2eB+c94oyEDWp2AOMeKzw0U79XAwQA 6Vdw== 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=hTQAbzTf9ULU0kxq5RVe3UvFkDJIkSogU54CcY+eeF4=; b=A1jbFNCXk0WbgtBd5A8lt3uLp8ImuGzFkcXkbxf2lMLKEy2Ws6PYwk9ywSUcdXUFRt QFQ2C0fTqMQVN72EACpeSKo6NLE/AegAz9afZI1/8NisjFoXtgnWZdYeJ0wUctNr5eCK xekFclkVaN0MDngjZfDAItRv1uXpTfbqndwghhZHmChLzyc3qL65PX7BluQDAfKvGsLH e88ePDWKZiVC1iU/yguNyH6ckD5uwQWVAT5/GTVrfjgAiV0cWg3dzNyGasj7i6cvKL2b 16LxTomzgn2OHKVfo1iv6KK//YGd25SmCzFGJ1sFTSuD0yotfBA/sWE5+bkV+RcFqLyv l4jQ== X-Gm-Message-State: AOAM531IfT6F/f3zharZ/r62FwYSaI4OhEnF9pmp/Ki8iaZdps+cqrCx F3xDk5ZRlNXnoB5AHBJKVTO2oYaqkib9LmYJZOgql0EWfHk= X-Google-Smtp-Source: ABdhPJyWNZ2gBBQuG7lJ++liv7Q1rZYSoJLFkIGtUOPiQnxMxNTSlFyrbhhgK0svspzcsPOFBGqFukAX0kQ9UvkZpNc= X-Received: by 2002:a65:40c8:: with SMTP id u8mr50716pgp.145.1628468935277; Sun, 08 Aug 2021 17:28:55 -0700 (PDT) MIME-Version: 1.0 References: <162846730406.22632.14734595494457390936@noble.neil.brown.name> In-Reply-To: <162846730406.22632.14734595494457390936@noble.neil.brown.name> From: Mike Javorski Date: Sun, 8 Aug 2021 17:28:44 -0700 Message-ID: Subject: Re: NFS server regression in kernel 5.13 (tested w/ 5.13.9) To: NeilBrown Cc: linux-nfs@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Appreciate the insights Neil. I will make an attempt to trigger/capture the fault if I can. - mike On Sun, Aug 8, 2021 at 5:01 PM NeilBrown wrote: > > On Mon, 09 Aug 2021, Mike Javorski wrote: > > I have been experiencing nfs file access hangs with multiple release > > versions of the 5.13.x linux kernel. In each case, all file transfers > > freeze for 5-10 seconds and then resume. This seems worse when reading > > through many files sequentially. > > A particularly useful debugging tool for NFS freezes is to run > > rpcdebug -m rpc -c all > > while the system appears frozen. As you only have a 5-10 second window > this might be tricky. > Setting or clearing debug flags in the rpc module (whether they are > already set or not) has a side effect if listing all RPC "tasks" which a > waiting for a reply. Seeing that task list can often be useful. > > The task list appears in "dmesg" output. If there are not tasks > waiting, nothing will be written which might lead you to think it didn't > work. > > As Chuck hinted, tcpdump is invaluable for this sort of problem. > tcpdump -s 0 -w /tmp/somefile.pcap port 2049 > > will capture NFS traffic. If this can start before a hang, and finish > after, it may contain useful information. Doing that in a way that > doesn't create an enormous file might be a challenge. It would help if > you found a way trigger the problem. Take note of the circumstances > when it seems to happen the most. If you can only produce a large file, > we can probably still work with it. > tshark -r /tmp/somefile.pcap > will report the capture one line per packet. You can look for the > appropriate timestamp, note the frame numbers, and use "editcap" > to extract a suitable range of packets. > > NeilBrown > > > > > > My server: > > - Archlinux w/ a distribution provided kernel package > > - filesystems exported with "rw,sync,no_subtree_check,insecure" options > > > > Client: > > - Archlinux w/ latest distribution provided kernel (5.13.9-arch1-1 at writing) > > - nfs mounted via /net autofs with "soft,nodev,nosuid" options > > (ver=4.2 is indicated in mount) > > > > I have tried the 5.13.x kernel several times since the first arch > > release (most recently with 5.13.9-arch1-1), all with similar results. > > Each time, I am forced to downgrade the linux package to a 5.12.x > > kernel (5.12.15-arch1 as of writing) to clear up the transfer issues > > and stabilize performance. No other changes are made between tests. I > > have confirmed the freezing behavior using both ext4 and btrfs > > filesystems exported from this server. > > > > At this point I would appreciate some guidance in what to provide in > > order to diagnose and resolve this issue. I don't have a lot of kernel > > debugging experience, so instruction would be helpful. > > > > - mike > > > >