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 A747AC04A94 for ; Thu, 10 Aug 2023 11:36:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235316AbjHJLgH (ORCPT ); Thu, 10 Aug 2023 07:36:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230142AbjHJLgF (ORCPT ); Thu, 10 Aug 2023 07:36:05 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2320510D; Thu, 10 Aug 2023 04:36:02 -0700 (PDT) Received: from [192.168.100.7] (unknown [59.103.218.230]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: usama.anjum) by madras.collabora.co.uk (Postfix) with ESMTPSA id D7E2D6607226; Thu, 10 Aug 2023 12:35:57 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1691667360; bh=Ylo0jog626GBLFmCxHv/u/pMzgKMQjdzVyIlxTz/kfs=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=c3wMH5VM3hNlrkHewhOK7FfM3f2aifd1UqrXE+x/Zw0J8n9B7IpsitR5hz20CS508 2E+qga//VJBn3Guk193xGVbdkJyWwmvu6oisN9g1gINdkZKHoPdGv5bYNzN6vfnhI5 L8CHIntrxq8jfkx1nZ6XDJB5+9+IOld11KJ7sx9agi0mk66zdmjjY/xrxyYahv40XJ 8qvEsKC8J00CR9PTG45O7ydojRUh+/uUD6C6osurpsDaipiq2BhwzKl2gOW2peDzhw pXNUN9gwoKH2mCV7RdHUFmCPnRXErrhHE6yt5cIqONYH931QWBg75OzfRywMq/UcJX auQdHwou1/c3Q== Message-ID: <6b34b825-6757-0053-68b2-97c7befc5720@collabora.com> Date: Thu, 10 Aug 2023 16:35:54 +0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.1 Cc: Muhammad Usama Anjum , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stable Subject: Re: [v6.1] kernel BUG in ext4_writepages Content-Language: en-US To: Baokun Li , syzbot , syzkaller-lts-bugs@googlegroups.com, Jan Kara , Theodore Ts'o , Andreas Dilger References: <00000000000081f8c905f6c24e0d@google.com> <87dcdf62-8a74-1fbf-5f10-f4f3231f774f@collabora.com> From: Muhammad Usama Anjum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/10/23 4:30 PM, Baokun Li wrote: > Hello! > > On 2023/8/10 18:49, Muhammad Usama Anjum wrote: >> Hi, >> >> Syzbot has reporting hitting this bug on 6.1.18 and 5.15.101 LTS kernels >> and provided reproducer as well. >> >>     BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)); >> >> I've copied the same config and reproduced the bug on 6.1.18, 6.1.44 and >> next-20230809. >> >> This part of code hasn't been changed from the time it was introduced >> 4e7ea81db53465 ("ext4: restructure writeback path"). I'm not sure why the >> inlined data is being destroyed before copying it somewhere else. >> >> Please consider this a report. >> >> Regards, >> Muhammad Usama Anjum > > We've already noticed this problem, which is caused by the fact that > > ext4_convert_inline_data() in ext4_page_mkwrite() is not protected by > > an inode_lock, so it can modify the state of the inode while someone > > else is holding the lock. > > Unfortunately we don't have a good solution for this at the moment, > > as adding inode_lock here could easily form an ABBA deadlock with > > mmap_lock. For a more detailed discussion see: > >      https://lkml.org/lkml/2023/5/30/894 Thank you so much for replying, explaining and this reference. > > >> >> On 3/13/23 11:34 AM, syzbot wrote: >>> syzbot has found a reproducer for the following issue on: >>> >>> HEAD commit: 1cc3fcf63192 Linux 6.1.18 >>> git tree: linux-6.1.y >>> console output: https://syzkaller.appspot.com/x/log.txt?x=10d4b342c80000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=157296d36f92ea19 >> ^ Kernel config >> >>> dashboard link: >>> https://syzkaller.appspot.com/bug?extid=a8068dd81edde0186829 >>> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) >>> 2.35.2 >>> userspace arch: arm64 >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13512ec6c80000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15ca0ff4c80000 >> ^ reproducers. C reproducer reproduces the bug easily. >> >>> Downloadable assets: >>> disk image: >>> https://storage.googleapis.com/syzbot-assets/0e4c0d43698b/disk-1cc3fcf6.raw.xz >>> vmlinux: >>> https://storage.googleapis.com/syzbot-assets/a4de39d735de/vmlinux-1cc3fcf6.xz >>> kernel image: >>> https://storage.googleapis.com/syzbot-assets/82bab928f6e3/Image-1cc3fcf6.gz.xz >>> mounted in repro: >>> https://storage.googleapis.com/syzbot-assets/bf2e21b96210/mount_0.gz >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the >>> commit: >>> Reported-by: syzbot+a8068dd81edde0186829@syzkaller.appspotmail.com >>> >>> ------------[ cut here ]------------ >>> kernel BUG at fs/ext4/inode.c:2746! >>> Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP >>> Modules linked in: >>> CPU: 0 PID: 11 Comm: kworker/u4:1 Not tainted 6.1.18-syzkaller #0 >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >>> Google 03/02/2023 >>> Workqueue: writeback wb_workfn (flush-7:0) >>> pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) >>> pc : ext4_writepages+0x35f4/0x35f8 fs/ext4/inode.c:2745 >>> lr : ext4_writepages+0x35f4/0x35f8 fs/ext4/inode.c:2745 >>> sp : ffff800019d16d40 >>> x29: ffff800019d17120 x28: ffff800008e691e4 x27: dfff800000000000 >>> x26: ffff0000de1f3ee0 x25: ffff800019d17590 x24: ffff800019d17020 >>> x23: ffff0000dd616000 x22: ffff800019d16f40 x21: ffff0000de1f4108 >>> x20: 0000008410000000 x19: 0000000000000001 x18: ffff800019d16a20 >>> x17: ffff80001572d000 x16: ffff8000083099b4 x15: 000000000000ba31 >>> x14: 00000000ffffffff x13: dfff800000000000 x12: 0000000000000001 >>> x11: ff80800008e6c7d8 x10: 0000000000000000 x9 : ffff800008e6c7d8 >>> x8 : ffff0000c099b680 x7 : 0000000000000000 x6 : 0000000000000000 >>> x5 : 0000000000000080 x4 : 0000000000000000 x3 : 0000000000000001 >>> x2 : 0000000000000000 x1 : 0000008000000000 x0 : 0000000000000000 >>> Call trace: >>> ext4_writepages+0x35f4/0x35f8 fs/ext4/inode.c:2745 >>> do_writepages+0x2e8/0x56c mm/page-writeback.c:2469 >>> __writeback_single_inode+0x228/0x1ec8 fs/fs-writeback.c:1587 >>> writeback_sb_inodes+0x9c0/0x1844 fs/fs-writeback.c:1878 >>> wb_writeback+0x4f8/0x1580 fs/fs-writeback.c:2052 >>> wb_do_writeback fs/fs-writeback.c:2195 [inline] >>> wb_workfn+0x460/0x11b8 fs/fs-writeback.c:2235 >>> process_one_work+0x868/0x16f4 kernel/workqueue.c:2289 >>> worker_thread+0x8e4/0xfec kernel/workqueue.c:2436 >>> kthread+0x24c/0x2d4 kernel/kthread.c:376 >>> ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 >>> Code: d4210000 97da5cfa d4210000 97da5cf8 (d4210000) >>> ---[ end trace 0000000000000000 ]--- >>> >>> -- BR, Muhammad Usama Anjum