Re: [PATCH v4] mtd: spi-nor: fix memory leak when using debugfs_lookup()

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michael Walle <michael@walle.cc>,
	linux-kernel@vger.kernel.org,
	Tudor Ambarus <tudor.ambarus@microchip.com>,
	Pratyush Yadav <pratyush@kernel.org>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	linux-mtd@lists.infradead.org
Subject: Re: [PATCH v4] mtd: spi-nor: fix memory leak when using debugfs_lookup()
Date: Mon, 6 Mar 2023 09:33:36 +0100	[thread overview]
Message-ID: <20230306093336.523832b0@xps-13> (raw)
In-Reply-To: <ZAWNtv0g6vmADGnb@kroah.com>

Hi Greg,

gregkh@linuxfoundation.org wrote on Mon, 6 Mar 2023 07:52:38 +0100:

> On Wed, Feb 08, 2023 at 05:15:41PM +0100, Michael Walle wrote:
> > Am 2023-02-08 17:02, schrieb Greg Kroah-Hartman:  
> > > When calling debugfs_lookup() the result must have dput() called on it,
> > > otherwise the memory will leak over time.  To solve this, remove the
> > > lookup and create the directory on the first device found, and then
> > > remove it when the module is unloaded.
> > > 
> > > Cc: Tudor Ambarus <tudor.ambarus@microchip.com>
> > > Cc: Pratyush Yadav <pratyush@kernel.org>
> > > Cc: Michael Walle <michael@walle.cc>
> > > Cc: Miquel Raynal <miquel.raynal@bootlin.com>
> > > Cc: Richard Weinberger <richard@nod.at>
> > > Cc: Vignesh Raghavendra <vigneshr@ti.com>
> > > Cc: linux-mtd@lists.infradead.org
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>  
> > 
> > Reviewed-by: Michael Walle <michael@walle.cc>
> > 
> > one nit below I didn't notice earlier, no need to send a new
> > patch version just for that.
> > 
> > ..
> >   
> > > +void spi_nor_debugfs_shutdown(void)
> > > +{
> > > +	if (rootdir)
> > > +		debugfs_remove(rootdir);  
> > 
> > debugfs_remove() already has a check for NULL.
> >   
> 
> Ah, good catch, I merged this in when I applied it to my tree, thanks!

Any reasons why you did apply this patch to your tree? It is a spi-nor
fix, I would have expected it to go through mtd.

Thanks,
Miquèl