linux-kernel - Re: lockdep issues with overlayfs

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Date:   Tue, 9 Jun 2020 12:53:50 -0400
From:   Waiman Long <longman@...hat.com>
To:     Miklos Szeredi <miklos@...redi.hu>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: Re: lockdep issues with overlayfs

On 6/9/20 11:07 AM, Miklos Szeredi wrote:
> While running xfstests[1] on overlayfs I get the following:
>
> BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
> turning off the locking correctness validator.
> [...]
>
> Then when doing cat /proc/lockdep_chains I get this Oops:
>
> BUG: unable to handle page fault for address: ffffffff83b36da8
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 2262067 P4D 2262067 PUD 2263063 PMD 0

Thanks for the information. There are some corruption in the lock chain 
data some garbage shows up in your lockdep_chains. I will try to 
reproduce the error to in order to figure out where the bug is.

Thanks,
Longman