Re: [syzbot] [btrfs?] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low! (4)

[David Sterba]

On Sat, Oct 21, 2023 at 07:40:53PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    78124b0c1d10 Merge branch 'for-next/core' into for-kernelci
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=1557da89680000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f27cd6e68911e026
> dashboard link: https://syzkaller.appspot.com/bug?extid=b2869947e0c9467a41b6
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=137ac45d680000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16e4640b680000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/bd512de820ae/disk-78124b0c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/a47a437b1d4f/vmlinux-78124b0c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/3ae8b966bcd7/Image-78124b0c.gz.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/d5d514495f15/mount_0.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b2869947e0c9467a41b6@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!

#syz invalid

This is a frequent warning, can be worked around by increasing
CONFIG_LOCKDEP_CHAINS_BITS in config (18 could be a good value but may
still not be enough).