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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 A4AACC433E2 for ; Tue, 15 Sep 2020 19:39:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53CF520770 for ; Tue, 15 Sep 2020 19:39:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tessares-net.20150623.gappssmtp.com header.i=@tessares-net.20150623.gappssmtp.com header.b="egkRtBub" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727935AbgIOTjj (ORCPT ); Tue, 15 Sep 2020 15:39:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728019AbgIOTin (ORCPT ); Tue, 15 Sep 2020 15:38:43 -0400 Received: from mail-ej1-x643.google.com (mail-ej1-x643.google.com [IPv6:2a00:1450:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B090C061352 for ; Tue, 15 Sep 2020 12:38:42 -0700 (PDT) Received: by mail-ej1-x643.google.com with SMTP id z23so6683280ejr.13 for ; Tue, 15 Sep 2020 12:38:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tessares-net.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=s8T/xfdPgHNj8zUD8Dev4ytzaOaIL61Me0jC59/f6ng=; b=egkRtBub72A0udarXLyx7kPiMFbZwxsdamaVoFNk6fnra45xH6+b1qu08DA4H5P14q xetyyxN5sf5gqn/2H/HatglN6yEKyZ42U6+lhqC/pnGz5T70MrjHENkX2vz7X41W3+JW alpjHNCximjdVxjju4pceLFUdI5o+mVhSE8ZH78vFtpdOQH4MPkuH6h1xDLvqb4zKOrv bXDk2fgNXtneCIfn7EbycNR+/brHucmInUL/jFy/EpsPw6Q/niRK2ggnlDZZiT84cgrt Oyg38QnQ7HMZ1Klg3HsGoWjySJ0wjMjVd7+Su+bnbpgFbS85diBrzIWBW3LcqMeyUDsb aceA== 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=s8T/xfdPgHNj8zUD8Dev4ytzaOaIL61Me0jC59/f6ng=; b=NDcYwd1g4uzeSOMytNThnUG/89ZcXRcy40Cu0UONbOL26DTvTfwYTb0btFvsQCSotk MeVAf+cblJmWJLaGsxBeSiBhKXkjin/U7uSoDxHSR+IzRFvHwgAdz5p9QQ8JQsj6nP/q CBOo7NGH5ZCjLA+1C7+PPAOR3+EQRbg+2Uq84nVR2yqu68fufD/TrI3r3BqZ29akv0kn yPGRRJu9g7awldHZUqB3nsa4YJ5W28Bh71fI3pI516+wVLXH/IhlXn+gt6NgJdoC9Nww S5g5E2m/mht6OJW6sbraeT/6DGDjSbcrs4PGAEI0tUa/bvYnakwKx9dwn/50/j/Zo3pS DKJQ== X-Gm-Message-State: AOAM532o1dQoalV1PetAWo4fycVB8Lo3vMVaKjyor1oOnHweELTDTmvi azmiXVYaq45gpf+MXZ5GfZqIGJ0p9GKU5Q8J X-Google-Smtp-Source: ABdhPJwf98cQYg59nWOxTJOT2LYyBb716h5ZTzsJtSJJboypj0hXqlJsypquvfCfPTpmlCY7mUhmDQ== X-Received: by 2002:a17:906:2752:: with SMTP id a18mr8819405ejd.350.1600198720550; Tue, 15 Sep 2020 12:38:40 -0700 (PDT) Received: from tsr-lap-08.nix.tessares.net ([2a02:578:85b0:e00:ec32:668e:7a20:c1cd]) by smtp.gmail.com with ESMTPSA id z18sm11038113ejw.94.2020.09.15.12.38.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Sep 2020 12:38:39 -0700 (PDT) Subject: Re: Kernel Benchmarking To: Linus Torvalds Cc: Michael Larabel , Matthew Wilcox , Amir Goldstein , Ted Ts'o , Andreas Dilger , Ext4 Developers List , Jan Kara , linux-fsdevel References: <0cbc959e-1b8d-8d7e-1dc6-672cf5b3899a@MichaelLarabel.com> <0daf6ae6-422c-dd46-f85a-e83f6e1d1113@MichaelLarabel.com> <20200912143704.GB6583@casper.infradead.org> <658ae026-32d9-0a25-5a59-9c510d6898d5@MichaelLarabel.com> <9550725a-2d3f-fa35-1410-cae912e128b9@tessares.net> <9a92bf16-02c5-ba38-33c7-f350588ac874@tessares.net> From: Matthieu Baerts Message-ID: Date: Tue, 15 Sep 2020 21:38:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 15/09/2020 21:24, Linus Torvalds wrote: > On Tue, Sep 15, 2020 at 12:01 PM Matthieu Baerts > wrote: > >> I forgot one important thing, I was on top of David Miller's net-next >> branch by reflex. I can redo the traces on top of linux-next if needed. > > Not likely an issue. > > I'll go stare at the page lock code again to see if I've missed > anything. I still suspect it's a latent ABBA deadlock that is just > much *much* easier to trigger with the synchronous lock handoff, but I > don't see where it is. > > I guess this is all fairly theoretical since we apparently need to do > that hybrid "limited fairness" patch anyway, and it fixes your issue, > but I hate not understanding the problem. I understand :) Thank you again for looking at this issue! Cheers, Matt -- Tessares | Belgium | Hybrid Access Solutions www.tessares.net