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,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 DF502C83018 for ; Mon, 30 Nov 2020 18:18:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86C9F206F9 for ; Mon, 30 Nov 2020 18:18:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="LXkCbQiH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388079AbgK3SRx (ORCPT ); Mon, 30 Nov 2020 13:17:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388072AbgK3SRw (ORCPT ); Mon, 30 Nov 2020 13:17:52 -0500 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4AD5C061A04 for ; Mon, 30 Nov 2020 10:16:50 -0800 (PST) Received: by mail-pf1-x42b.google.com with SMTP id w187so10950156pfd.5 for ; Mon, 30 Nov 2020 10:16:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.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=zNPV/E/GVDzH5U+Ow7xgO0eNGeZXdhdQWf1tOSwgd2w=; b=LXkCbQiHy9b9FLU75B9bwVbtlkgp70lmRg7LgcZjq1q3HONk2XsBEHtwpj6x0UbVSd tOQt3L5Ms24SfzhJUD2Hh4Hq8ZVbM9tanve70zbm+CZX89/m/wIX2yVJiA9+BucUpm3C 9RqSEvRyygmwChyFeIbDQGSN7ns3wCXqSMeXzr0gR+VrIdMp25r2rvN2Pbi+L+JW+0ia 2T5/3SerPn+Ol9W1YrVzOF/kYhFsALcob+aZki6V2Td6e9//wdMdwnOr9vlhPVlqprNq 1TYugjyeSyrA7YMKffm8wWkrnBUPF4HyAAQJKJPP6qTMzOvWBvXDn9OBBz7U/zwGswxs XQwA== 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=zNPV/E/GVDzH5U+Ow7xgO0eNGeZXdhdQWf1tOSwgd2w=; b=UlS6lu3hC9nt8KRq6vtYYtlr6gpt9WrVGiyaZntHSozlEV6Bsripved+7duaXUYIjQ r2asXFGEVhaQqHReLzagSsPNwA13ZsgQISkvfV+mIQzTi/2wsbm5b3KziT5iF3etW5P5 1MDbHm9GgBldKa2r96vq6Lxgr5ANb1c5imeHMPjrza2KIVsUXL+u8uvNJdJBNlsifXE3 xfDjXOF3DBjCr9uSoQnpRyTpR6/OqUmnMY7lJff7uCZy8OrQJfnhlRG5A3OnqAQUKDwg r+xLuRdPKfS4VYWP7zThzuvkqzaiNBXIKG20z+okp4SEIvE8eGmJSbuRLKbHPsHdb4a4 T4Zw== X-Gm-Message-State: AOAM5335Zq1xJ6uc/BvQUC72Dg1NgVRs2+a0r5mvSqdcIWk/oS4yGxkC iBnK8+HJCywWnvnY24umLPnP+fkiVLb9Pg== X-Google-Smtp-Source: ABdhPJymUTrvQI6L+Ma2LDfsq54/WMjLfYOrzgM5E18qNr+D1vYk+BsvKUiYgu+E0KDWsE3N5Yun0Q== X-Received: by 2002:aa7:91c7:0:b029:197:e389:fb26 with SMTP id z7-20020aa791c70000b0290197e389fb26mr20235917pfa.20.1606760210294; Mon, 30 Nov 2020 10:16:50 -0800 (PST) Received: from [192.168.1.134] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id a23sm81119pju.31.2020.11.30.10.16.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Nov 2020 10:16:49 -0800 (PST) Subject: Re: Lockdep warning on io_file_data_ref_zero() with 5.10-rc5 To: Pavel Begunkov , Nadav Amit Cc: linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, LKML , Alexander Viro References: From: Jens Axboe Message-ID: <13baf2c4-a403-41fc-87ca-6f5cb7999692@kernel.dk> Date: Mon, 30 Nov 2020 11:16:48 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 11/28/20 5:13 PM, Pavel Begunkov wrote: > On 28/11/2020 23:59, Nadav Amit wrote: >> Hello Pavel, >> >> I got the following lockdep splat while rebasing my work on 5.10-rc5 on the >> kernel (based on 5.10-rc5+). >> >> I did not actually confirm that the problem is triggered without my changes, >> as my iouring workload requires some kernel changes (not iouring changes), >> yet IMHO it seems pretty clear that this is a result of your commit >> e297822b20e7f ("io_uring: order refnode recycling”), that acquires a lock in >> io_file_data_ref_zero() inside a softirq context. > > Yeah, that's true. It was already reported by syzkaller and fixed by Jens, but > queued for 5.11. Thanks for letting know anyway! > > https://lore.kernel.org/io-uring/948d2d3b-5f36-034d-28e6-7490343a5b59@kernel.dk/T/#t > > > Jens, I think it's for the best to add it for 5.10, at least so that lockdep > doesn't complain. Yeah maybe, though it's "just" a lockdep issue, it can't trigger any deadlocks. I'd rather just keep it in 5.11 and ensure it goes to stable. This isn't new in this series. -- Jens Axboe