linux-kernel - Re: [PATCH] irqdomain: remove debugfs_file from struct irq

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Date:   Thu, 18 Feb 2021 09:40:58 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Michael Walle <michael@...le.cc>
Cc:     linux-kernel@...r.kernel.org, maz@...nel.org, tglx@...utronix.de
Subject: Re: [PATCH] irqdomain: remove debugfs_file from struct irq_domain

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@...lle01) (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