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Date:   Thu, 18 Feb 2021 09:40:58 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Michael Walle <michael@walle.cc>
Cc:     linux-kernel@vger.kernel.org, maz@kernel.org, tglx@linutronix.de
Subject: Re: [PATCH] irqdomain: remove debugfs_file from struct irq_domain
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References: <YCvYV53ZdzQSWY6w@kroah.com>
 <20210217195717.13727-1-michael@walle.cc>
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On Wed, Feb 17, 2021 at 08:57:17PM +0100, Michael Walle wrote:
> Hi Greg,
> 
> > There's no need to keep around a dentry pointer to a simple file that
> > debugfs itself can look up when we need to remove it from the system.
> > So simplify the code by deleting the variable and cleaning up the logic
> > around the debugfs file.
> 
> This will generate the following oops on my board (arm64,
> freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts). In debugfs_lookup()
> debugfs_mount is NULL.
> 
> [    0.000000] Linux version 5.11.0-next-20210217-00014-g41e0e92a2d05 (mwalle@mwalle01) (aarch64-linux-gnu-gcc (Debian 8.3.0-2) 8.3.0, GNU ld (GNU Binutils for Debian) 2.31.1) #69 SMP PREEMPT Wed Feb 17 20:47:10 CET 2021
> [..]
> [    0.000000] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> [    0.000000] Mem abort info:
> [    0.000000]   ESR = 0x96000004

<snip>

Back to this log, do you see:
	"Unable to pin filesystem for file "
anywhere before this crash?

thanks,

greg k-h