From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751280AbeEUMuF (ORCPT ); Mon, 21 May 2018 08:50:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:55431 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbeEUMuD (ORCPT ); Mon, 21 May 2018 08:50:03 -0400 Date: Mon, 21 May 2018 14:50:00 +0200 From: Jan Kara To: syzbot Cc: adilger.kernel@dilger.ca, jack@suse.cz, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tytso@mit.edu Subject: Re: WARNING in ext4_set_page_dirty Message-ID: <20180521125000.hlgdsvlzlr7xw3bx@quack2.suse.cz> References: <089e0825cec8180a2b0568c4ee1d@google.com> <0000000000003a8d73056cb11ca3@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000003a8d73056cb11ca3@google.com> User-Agent: NeoMutt/20170421 (1.8.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun 20-05-18 23:07:02, syzbot wrote: > syzbot has found a reproducer for the following crash on: > > HEAD commit: 771c577c23ba Linux 4.17-rc6 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=108c9f37800000 > kernel config: https://syzkaller.appspot.com/x/.config?x=982e2df1b9e60b02 > dashboard link: https://syzkaller.appspot.com/bug?extid=9a44753ac327c557796a > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1655584f800000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15134357800000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+9a44753ac327c557796a@syzkaller.appspotmail.com > > WARNING: CPU: 0 PID: 4577 at fs/ext4/inode.c:3894 > ext4_set_page_dirty+0x28d/0x330 fs/ext4/inode.c:3894 > Kernel panic - not syncing: panic_on_warn set ... Looking at the reproducer, this is the issue we have been speaking about at LSF/MM - direct IO read dirties pages after writeback has written them out and so we don't expect them to be dirtied. If someone told me I would not believe this is possible to hit by fuzzing ;) Good job from the syzkaller guys! Honza -- Jan Kara SUSE Labs, CR