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From:   Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Date:   Thu, 4 Aug 2022 00:28:31 +0500
Message-ID: <CABXGCsMNF_SKns-av1kAWtR5Yd7u6sjwsFT9er8tSebfuLG8VQ@mail.gmail.com>
Subject: Re: BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
To:     dsterba@suse.cz, Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>,
        Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
Cc:     Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        dvyukov@google.com
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On Tue, Jul 26, 2022 at 9:47 PM David Sterba <dsterba@suse.cz> wrote:
>
> On Tue, Jul 26, 2022 at 05:32:54PM +0500, Mikhail Gavrilov wrote:
> > Hi guys.
> > Always with intensive writing on a btrfs volume, the message "BUG:
> > MAX_LOCKDEP_CHAIN_HLOCKS too low!" appears in the kernel logs.
>
> Increase the config value of LOCKDEP_CHAINS_BITS, default is 16, 18
> tends to work.

I confirm that after bumping LOCKDEP_CHAINS_BITS to 18 several days of
continuous writing on the BTRFS partition with different files with a
total size of 10Tb I didn't see this kernel bug message again.
Tetsuo, I saw your commit 5dc33592e95534dc8455ce3e9baaaf3dae0fff82 [1]
set for LOCKDEP_CHAINS_BITS default value 16.
Why not increase LOCKDEP_CHAINS_BITS to 18 by default?
Thanks.


[1] https://github.com/torvalds/linux/blame/master/lib/Kconfig.debug#L1387

-- 
Best Regards,
Mike Gavrilov.