Re: [syzbot] [btrfs?] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low! (3)

[David Sterba]

On Tue, Oct 17, 2023 at 08:53:45AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c295ba49917a 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=135804fe680000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f27cd6e68911e026
> dashboard link: https://syzkaller.appspot.com/bug?extid=6aa88a2d31fbec170f8b
> 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=17d48d09680000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13498275680000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/045554f2bee6/disk-c295ba49.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/ba2705f8a872/vmlinux-c295ba49.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/e36242e95b79/Image-c295ba49.gz.xz
> mounted in repro #1: https://storage.googleapis.com/syzbot-assets/39a4eecc45c3/mount_0.gz
> mounted in repro #2: https://storage.googleapis.com/syzbot-assets/3a9106a526c9/mount_1.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+6aa88a2d31fbec170f8b@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).