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=-7.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 A8927C4363A for ; Mon, 26 Oct 2020 11:56:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A3A122265 for ; Mon, 26 Oct 2020 11:56:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="MjxjTVAi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1774563AbgJZL4K (ORCPT ); Mon, 26 Oct 2020 07:56:10 -0400 Received: from mx2.suse.de ([195.135.220.15]:37382 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1768348AbgJZL4G (ORCPT ); Mon, 26 Oct 2020 07:56:06 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1603713364; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JrUGiQKa+nOgpLR5+3rPTLPO7SRFbfxNLKSQsjR/B3s=; b=MjxjTVAiOfYhK3XVQIdkQb8lFquMPAQpngX7TK0Z9Hi2JU3hJqKttoLw4PMbqU3YMWLwfK 7K/S4qzkc6UjhuKNJ83dnujc6fHvHo9dROnoAvhE3HHn5RJ7kjdSypyQjpuCDpHqDJKcKO VcW7P2n41IrrM9LVJymJALYDnzdVrMU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 59E6DAC8B; Mon, 26 Oct 2020 11:56:04 +0000 (UTC) Subject: Re: possible lockdep regression introduced by 4d004099a668 ("lockdep: Fix lockdep recursion") To: Peter Zijlstra Cc: LKML , Jan Kara , David Sterba References: <20201026114009.GN2594@hirez.programming.kicks-ass.net> From: Filipe Manana Message-ID: <0c0d815c-bd5a-ff2d-1417-28a41173f2b4@suse.com> Date: Mon, 26 Oct 2020 11:56:03 +0000 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: <20201026114009.GN2594@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/10/20 11:40, Peter Zijlstra wrote: > On Mon, Oct 26, 2020 at 11:26:49AM +0000, Filipe Manana wrote: >> Hello, >> >> I've recently started to hit a warning followed by tasks hanging after >> attempts to freeze a filesystem. A git bisection pointed to the >> following commit: >> >> commit 4d004099a668c41522242aa146a38cc4eb59cb1e >> Author: Peter Zijlstra >> Date: Fri Oct 2 11:04:21 2020 +0200 >> >> lockdep: Fix lockdep recursion >> >> This happens very reliably when running all xfstests with lockdep >> enabled, and the tested filesystem is btrfs (haven't tried other >> filesystems, but it shouldn't matter). The warning and task hangs always >> happen at either test generic/068 or test generic/390, and (oddly) >> always have to run all tests for it to trigger, running those tests >> individually on an infinite loop doesn't seem to trigger it (at least >> for a couple hours). >> >> The warning triggered is at fs/super.c:__sb_start_write() which always >> results later in several tasks hanging on a percpu rw_sem: >> >> https://pastebin.com/qnLvf94E >> >> What happens is percpu_rwsem_is_held() is apparently returning a false >> positive, > > That smells like the same issue reported here: > > https://lkml.kernel.org/r/20201022111700.GZ2651@hirez.programming.kicks-ass.net > > Make sure you have commit: > > f8e48a3dca06 ("lockdep: Fix preemption WARN for spurious IRQ-enable") > > (in Linus' tree by now) and do you have CONFIG_DEBUG_PREEMPT enabled? Yes, CONFIG_DEBUG_PREEMPT is enabled. I'll try with that commit and let you know, however it's gonna take a few hours to build a kernel and run all fstests (on that test box it takes over 3 hours) to confirm that fixes the issue. Thanks for the quick reply! > > > >