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Date:   Wed, 2 Nov 2022 23:53:52 +0100
From:   David Sterba <dsterba@suse.cz>
To:     syzbot <syzbot+9c37714c07194d816417@syzkaller.appspotmail.com>
Cc:     clm@fb.com, dsterba@suse.com, josef@toxicpanda.com,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in btrfs_commit_transaction
Message-ID: <20221102225352.GJ5824@twin.jikos.cz>
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On Wed, Nov 02, 2022 at 10:46:53AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    b229b6ca5abb Merge tag 'perf-tools-fixes-for-v6.1-2022-10-..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12db9c7e880000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
> dashboard link: https://syzkaller.appspot.com/bug?extid=9c37714c07194d816417
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17401632880000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13176716880000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ba5b49fa77de/disk-b229b6ca.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7c061f2ae4dc/vmlinux-b229b6ca.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/bc45c1300e9b/bzImage-b229b6ca.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/62077524a72d/mount_0.gz
> 
> Bisection is inconclusive: the issue happens on the oldest tested release.
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14e432a6880000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=16e432a6880000
> console output: https://syzkaller.appspot.com/x/log.txt?x=12e432a6880000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9c37714c07194d816417@syzkaller.appspotmail.com
> 
> BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1)
> BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2)
> BTRFS info (device loop0): checking UUID tree
> BTRFS warning (device loop0): Skipping commit of aborted transaction.
> ------------[ cut here ]------------
> BTRFS: Transaction aborted (error -12)

-12 is ENOMEM, so another point for adding it to the list of exceptions
and not reporting the stacktrace. We have other warnings or assertions
to catch bad cleanup after errors.