Received-SPF: pass (google.com: domain of linux-kernel+bounces-64047-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Tue, 13 Feb 2024 19:01:11 +0100
From: David Sterba <dsterba@suse.cz>
To: syzbot <syzbot+5fd11a1f057a67a03a1b@syzkaller.appspotmail.com>
Cc: anand.jain@oracle.com, brauner@kernel.org, clm@fb.com, dsterba@suse.com,
	johannes.thumshirn@wdc.com, josef@toxicpanda.com,
	linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [btrfs?] WARNING in btrfs_create_pending_block_groups
Message-ID: <20240213180111.GE355@twin.jikos.cz>
Reply-To: dsterba@suse.cz
References: <0000000000000faabc05ee84f596@google.com>
 <000000000000a545940611434746@google.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <000000000000a545940611434746@google.com>
User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12)

On Tue, Feb 13, 2024 at 05:22:02AM -0800, syzbot wrote:
> syzbot suspects this issue was fixed by commit:
> 
> commit a1912f712188291f9d7d434fba155461f1ebef66
> Author: Josef Bacik <josef@toxicpanda.com>
> Date:   Wed Nov 22 17:17:55 2023 +0000
> 
>     btrfs: remove code for inode_cache and recovery mount options

This does not look like a fix, it's an unrelated change, the reported
problem probably depends on timing.

> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=113ba042180000
> start commit:   a4d7d7011219 Merge tag 'spi-fix-v6.4-rc5' of git://git.ker..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=7474de833c217bf4
> dashboard link: https://syzkaller.appspot.com/bug?extid=5fd11a1f057a67a03a1b

The log says that there's an attempt do
"balance: start -f -susage=6,vrange=0..9223372036854775809"

which looks suspicious but should be otherwise harmless, the range is
only considered. What is possible problem is that it's for the system
block group:

nfo (device loop0): balance: start -f -susage=6,vrange=0..9223372036854775809
------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)
WARNING: CPU: 0 PID: 5028 at fs/btrfs/block-group.c:2686 btrfs_create_pending_block_groups+0x10b7/0x1220 fs/btrfs/block-group.c:2686
Modules linked in:
CPU: 0 PID: 5028 Comm: syz-executor115 Not tainted 6.6.0-syzkaller-00207-g14ab6d425e80 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:btrfs_create_pending_block_groups+0x10b7/0x1220 fs/btrfs/block-group.c:2686