linux-kernel - Re: [BUG] btrfs: MAX_LOCKDEP_CHAIN

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Date:   Tue, 27 Jun 2023 18:27:02 +0200
From:   Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>
To:     dsterba@...e.cz
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>
Subject: Re: [BUG] btrfs: MAX_LOCKDEP_CHAIN_HLOCKS too low!

Hi, Qu, David,

On 6/27/23 16:27, David Sterba wrote:
> On Tue, Jun 27, 2023 at 08:19:37AM +0800, Qu Wenruo wrote:
>>
>> On 2023/6/27 07:40, Mirsad Goran Todorovac wrote:
>>> Hi,
>>>
>>> There is a bug apparently in btrfs file system.
>>>
>>> The platform is an assembled box with Ryzen 9 processor and ASRock X670E PG
>>> Lightning motherboard.
>>>
>>> I do not have a reproducer, just kernel log:
>>>
>>> Jun 26 20:41:58 defiant kernel: [ 2273.786736] BUG:
>>> MAX_LOCKDEP_CHAIN_HLOCKS too low!
>>
>> This is really what it said.
>>
>> The setting is too low for certain workload.
>>
>> In fact Fedora is already increasing this value.
>> If you want lockdep, I guess that's the only way to go.
> 
> https://btrfs.readthedocs.io/en/latest/dev/Development-notes.html#bug-max-lockdep-chain-hlocks-too-low
> 
> As the reports will probably keep coming until lockdep changes I'll move
> the answer to a more user-visible page.

Thank you for your prompt response. It wasn't obvious from the kernel
message though which .config setting needs adjustment.

I am yet unable to tell whether the lockdep setting being too low and
turning off the locking correctness validator caused the kernel crash, but
I will know more after restarting the kselftest with the new lockdep
setting ...

Best regards,
Mirsad Todorovac