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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7D4FC77B60 for ; Sun, 30 Apr 2023 16:34:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231126AbjD3QeR (ORCPT ); Sun, 30 Apr 2023 12:34:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229478AbjD3QeQ (ORCPT ); Sun, 30 Apr 2023 12:34:16 -0400 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB9A21992 for ; Sun, 30 Apr 2023 09:34:14 -0700 (PDT) Received: from letrec.thunk.org ([76.150.80.181]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 33UGY1ga023705 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 30 Apr 2023 12:34:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1682872444; bh=daAet6FPuur0yMX2pnkPYpb+BJN0RIXr+ldUhubDhHs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=LVqLcgbiGFlC4KF2IW4r0hLrbQOBH4tj8n2LlFEWtF1j1S0dqSnOgw2SS+R8J3ocE iiVqMct6KJwWNT+0joP1OJRTpMAJnvY5BORVbTOBRIjk8b0/rhjGYsBKlHP6MY5FFD gWGvV5aeFr2GCliarkSlbAc1peXSr7wwuU0HvgBA17FOwe+4kdA3D7RDXwIBQB0Urz N2OZViG52TqO7/l8VvD+xiKfsAOYYNd7oLORyPXbB1YGm9vNkUBkvmDY3eakwvSIVi S96sq8NuJYblZCzbIDTw0SP7jsTmNu2kzkKGCARioBaGyjfZX9+JlEWxC+BU1I0lhH m60wF5Yoq0eaw== Received: by letrec.thunk.org (Postfix, from userid 15806) id 9BB698C023E; Sun, 30 Apr 2023 12:34:00 -0400 (EDT) Date: Sun, 30 Apr 2023 12:34:00 -0400 From: "Theodore Ts'o" To: Jan Kara Cc: linux-ext4@vger.kernel.org, Christian Brauner , syzbot+aacb82fca60873422114@syzkaller.appspotmail.com, syzbot+6b7df7d5506b32467149@syzkaller.appspotmail.com Subject: Re: [PATCH] ext4: Fix lockdep warning when enabling MMP Message-ID: References: <20230411121019.21940-1-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230411121019.21940-1-jack@suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue, Apr 11, 2023 at 02:10:19PM +0200, Jan Kara wrote: > When we enable MMP in ext4_multi_mount_protect() during mount or > remount, we end up calling sb_start_write() from write_mmp_block(). This > triggers lockdep warning because freeze protection ranks above s_umount > semaphore we are holding during mount / remount. The problem is harmless > because we are guaranteed the filesystem is not frozen during mount / > remount but still let's fix the warning by not grabbing freeze > protection from ext4_multi_mount_protect(). > > Reported-by: syzbot+aacb82fca60873422114@syzkaller.appspotmail.com I believe this is the wrong Reported-by. The correct one looks like it should be: Reported-by: syzbot+6b7df7d5506b32467149@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=ab7e5b6f400b7778d46f01841422e5718fb81843 It's also helpful to add a Link line to the Syzkaller dashboard to make it easier to find the relevant Syzbot report. I'll put this on my todo list to grab for the next batch of ext4 fixups. - Ted