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=-3.9 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,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 76E4EC4363A for ; Mon, 26 Oct 2020 11:40:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C7CB22265 for ; Mon, 26 Oct 2020 11:40:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NuU1N7sN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1773926AbgJZLkX (ORCPT ); Mon, 26 Oct 2020 07:40:23 -0400 Received: from merlin.infradead.org ([205.233.59.134]:41156 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1773910AbgJZLkV (ORCPT ); Mon, 26 Oct 2020 07:40:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=k3myULEFtog5AWC/ZKa5hJLaQTgjEDatFr9wR9ogfpo=; b=NuU1N7sN8NattmmlDC8V+bEd+l zfhZdRaZvHfaBPsfUKrp9qaC6tt+N3brens4A/LsYDP4Z0om3Kbwc7dxeqMVN2AlPpfMM2rwrlTkS LNf768HPO4jP2dDNcWvlCTAmMmxtdKkWBcppfP1fqQ4eCjlkJazAxZiAyKz8fndNkCCHqvD0yy0lX Xc5waFkHH7ky9Ss13la9z7EQ1ON52GBv1QyqWx5sOCQh3E1ifK9u5/HguoELPwpzQdBLLi/DXGXbj MJrF7j84cYhUyINJcsVB4/niMRlJiA4tuiD+rzvzNIwsPaCfzrISQFJtkKzTb22VmCNYwhqZF2+0G XR72hLow==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kX0rF-0005tu-7c; Mon, 26 Oct 2020 11:40:13 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id BE09F302526; Mon, 26 Oct 2020 12:40:09 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AA5342B411E57; Mon, 26 Oct 2020 12:40:09 +0100 (CET) Date: Mon, 26 Oct 2020 12:40:09 +0100 From: Peter Zijlstra To: Filipe Manana Cc: LKML , Jan Kara , David Sterba Subject: Re: possible lockdep regression introduced by 4d004099a668 ("lockdep: Fix lockdep recursion") Message-ID: <20201026114009.GN2594@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?