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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, T_DKIMWL_WL_MED,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id DE614C004E4 for ; Wed, 13 Jun 2018 15:56:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 93C352086A for ; Wed, 13 Jun 2018 15:56:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="CmS8s8OX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 93C352086A Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935971AbeFMP4F (ORCPT ); Wed, 13 Jun 2018 11:56:05 -0400 Received: from mail-pl0-f68.google.com ([209.85.160.68]:35669 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935694AbeFMP4D (ORCPT ); Wed, 13 Jun 2018 11:56:03 -0400 Received: by mail-pl0-f68.google.com with SMTP id k1-v6so1794618plt.2 for ; Wed, 13 Jun 2018 08:56:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=ynJ21TXU/tX5WK70IqFau6rKUf9vU66RiXtFD0kQf18=; b=CmS8s8OXtmzlQXKG7gSlWjkrmcjnLmZ5keabrLLy0L2tO6LbDNWqCrHM7h2TTgj/+h Zaoa2H1e21YbbZlhlPSbIkUL/7F6k+O/fYyo+U5UvNyt8CLB5Gq6BitRNcsn7bLpWwkT 6H2LpIPvP1HxIaTwkRFg5HKv/ulIQ9Nmzzg0zk+NA16j1CUQnz/SwooJiqv0o/XIhfK8 VwH06DjIwy74LuzL4lJssiu9rxHSS6J0N9VPg91JzV8qMzVNHgnver2Uki+amsgB6OE3 zjHPLAutSNq2N4VWFlNbSh+lkoXypIyB4INPwNTRj/ZeWaeNZzApkRc6odl429pXlLqA RzWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=ynJ21TXU/tX5WK70IqFau6rKUf9vU66RiXtFD0kQf18=; b=GaRb1Ru+2QYmIUoBfBnov/Spi4w4WQpX+YWyPsoCDFCgjQY0DF62APdsG2kRlKbHHV JVXFU/WOSU7pIiTvEeT+xUkT5/+Nfh6gzA40yAnRCDn9WJMj0iD8qfhPbkurUvCcGmpb lqIjZ59rH61KW6iXb5Gin7pVxMpPKiv1hSBIFnll0w8G9y+qkMfmp9dGd6Ywey5tD+qd 2TSqhgW0eFpSGsBShfvIP0wWKvzQe1FMbyk6NoXiqlUGytesr9mH4dchfGqwqgqxjktZ kM1cQg1x4jVZ1mGQYc+/Znqw64B1NCP2obJ79CiMcQ6Aq+BDNgATuooDoPfMG+RuBpUv Rasw== X-Gm-Message-State: APt69E3NhLndef9LEMIESYVL2Nt1Zc0a9oqi+/+xxpfsRqgiKp9xpTEV FHsk4Q3+ZEbERF10e53ctB/G37K7TlLBPlzD2hM/CA== X-Google-Smtp-Source: ADUXVKKGPEb4iwBLajv9p2PXqQVvInTV/jDKAyIrvj8KUhtxApAbCdxWi7kskCQl1tYPzgK6RtzkNHX37Sapg8tDoQg= X-Received: by 2002:a17:902:ab95:: with SMTP id f21-v6mr5615623plr.264.1528905362728; Wed, 13 Jun 2018 08:56:02 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a17:90a:de2:0:0:0:0 with HTTP; Wed, 13 Jun 2018 08:55:42 -0700 (PDT) In-Reply-To: <20180521125000.hlgdsvlzlr7xw3bx@quack2.suse.cz> References: <089e0825cec8180a2b0568c4ee1d@google.com> <0000000000003a8d73056cb11ca3@google.com> <20180521125000.hlgdsvlzlr7xw3bx@quack2.suse.cz> From: Dmitry Vyukov Date: Wed, 13 Jun 2018 17:55:42 +0200 Message-ID: Subject: Re: WARNING in ext4_set_page_dirty To: Jan Kara Cc: syzbot , Andreas Dilger , linux-ext4@vger.kernel.org, LKML , syzkaller-bugs , "Theodore Ts'o" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 21, 2018 at 2:50 PM, Jan Kara wrote: > 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! Thanks, Jan! Very nice to hear. I believe we are not yet at the limit of what's possible :)