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,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 6806FC4363D for ; Wed, 21 Oct 2020 00:42:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 200CD22251 for ; Wed, 21 Oct 2020 00:42:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="ElApT+HX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439723AbgJUAmc (ORCPT ); Tue, 20 Oct 2020 20:42:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2439705AbgJUAmb (ORCPT ); Tue, 20 Oct 2020 20:42:31 -0400 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 204D3C0613CE for ; Tue, 20 Oct 2020 17:42:31 -0700 (PDT) Received: by mail-pf1-x441.google.com with SMTP id e10so448284pfj.1 for ; Tue, 20 Oct 2020 17:42:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=B3KB6nIVt2KuhQ4iDNkhmd6uAR4HfgCoAa05p/jW19Q=; b=ElApT+HXih0ss1XvmHd9UcfeW8dj33YfcSwnyCoVAHoLn7yqtPZkW6mPZmQar97WjO JZYZKqDRxRw3XDXuk+oX0LKHLeWKGlej5lVE3oy1ZC/ZrBRm7aKp+o6QyEc5C5oRA1B0 txB2YF0ScgvGrHjTDoY7nNI4pkCV4F01XzAK3v+llzRocaHvFiz2x7UzQqYSmqMyfDg9 3+0ZYuMMzgnJrf2mEvObuMiuvuT5K/UjhFSssQ3AW3bUUgkK3Yz1o1y9ct8Ad2k2IK1a 8fnZF7i9mbDv01pnLSI7yIMkVVM8+YcHvE7pzjHetRQhPv3qK0R0CNdBPC6wkEkgcgKa HdsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=B3KB6nIVt2KuhQ4iDNkhmd6uAR4HfgCoAa05p/jW19Q=; b=PN+9jrOyjwtcImfNi47TTeHpE2KC69x779dvppyO9YKET2RmSkjnkaeOmyPJvPKAyr rvt5xp7Fs2enrvQa9lS72eE0js/w1WaC/CY9Ysh524xpJoc+zcoUmGKT08ufqYQmz27q DmHlVOVZVaT0QVTE5y5pN4MzNgHPrrtJzJAhp6bGRkY3v+S3AqgpY13arRXd1VsUhAYk kFHY40MqSK4iLVNrrM+RKVEE0Hv7Ji7v5RVMjpw5fmu+waIYhxrQGY8A/xb1EuK/EEkH OblcTMsM7ChvzFd7fgPmpGAqbrkIbJ0S0Cblwmf8uwpXWh36/6SSjpANPPllcOWpzEsc h1OQ== X-Gm-Message-State: AOAM531N5D5WV93MBsgBnCMfDkmGMNZsdCt24iWbEhCk0fNbC3voqm7b kLPtoHxd2gNXaLlFsJHyYqHAkw== X-Google-Smtp-Source: ABdhPJxwKSunRCi9dWZskbMa6ou3vB49+WHIvU/DfPo3Z1G+sCI4a11vUWDI20ZrVClak4SpAp4xkw== X-Received: by 2002:a63:1f0f:: with SMTP id f15mr783464pgf.312.1603240950693; Tue, 20 Oct 2020 17:42:30 -0700 (PDT) Received: from leoy-ThinkPad-X240s ([14.192.49.12]) by smtp.gmail.com with ESMTPSA id kb15sm244562pjb.17.2020.10.20.17.42.28 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 20 Oct 2020 17:42:30 -0700 (PDT) Date: Wed, 21 Oct 2020 08:42:23 +0800 From: Leo Yan To: Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] perf lock: Don't free "lock_seq_stat" if read_count isn't zero Message-ID: <20201021004223.GA7226@leoy-ThinkPad-X240s> References: <20201021002619.28072-1-leo.yan@linaro.org> <20201021002619.28072-2-leo.yan@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201021002619.28072-2-leo.yan@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, On Wed, Oct 21, 2020 at 08:26:19AM +0800, Leo Yan wrote: > When execute command "perf lock report", it hits failure and outputs log > as follows: > > perf: builtin-lock.c:623: report_lock_release_event: Assertion `!(seq->read_count < 0)' failed. > Aborted > > This is an imbalance issue. The locking sequence structure > "lock_seq_stat" contains the reader counter and it is used to check if > the locking sequence is balance or not between acquiring and releasing. > > If the tool wrongly frees "lock_seq_stat" when "read_count" isn't zero, > the "read_count" will be reset to zero when allocate a new structure at > the next time; thus it causes the wrong counting for reader and finally > results in imbalance issue. > > To fix this issue, if detects "read_count" is not zero (means still > have read user in the locking sequence), goto the "end" tag to skip > freeing structure "lock_seq_stat". Please ignore this patch set and directly to review patch set v2; I forgot adding "fixes" tag in this patch, so updated in patch set v2. Sorry for spamming. Leo