Date:   Mon, 6 Mar 2023 12:05:58 +0100
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()
Message-ID: <20230306120558.00f614fb@xps-13>
In-Reply-To: <ZAWuvRHVVV3hTm0e@kroah.com>
References: <20230208160230.2179905-1-gregkh@linuxfoundation.org>
        <f60870dee13900252e0b13fb2f5f05b5@walle.cc>
        <ZAWNtv0g6vmADGnb@kroah.com>
        <20230306093336.523832b0@xps-13>
        <ZAWuvRHVVV3hTm0e@kroah.com>
Organization: Bootlin
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Hi Greg,

gregkh@linuxfoundation.org wrote on Mon, 6 Mar 2023 10:13:33 +0100:

> On Mon, Mar 06, 2023 at 09:33:36AM +0100, Miquel Raynal wrote:
> > Hi Greg,
> >=20
> > gregkh@linuxfoundation.org wrote on Mon, 6 Mar 2023 07:52:38 +0100:
> >  =20
> > > On Wed, Feb 08, 2023 at 05:15:41PM +0100, Michael Walle wrote: =20
> > > > Am 2023-02-08 17:02, schrieb Greg Kroah-Hartman:   =20
> > > > > 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 th=
en
> > > > > remove it when the module is unloaded.
> > > > >=20
> > > > > 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>   =
=20
> > > >=20
> > > > Reviewed-by: Michael Walle <michael@walle.cc>
> > > >=20
> > > > one nit below I didn't notice earlier, no need to send a new
> > > > patch version just for that.
> > > >=20
> > > > ..
> > > >    =20
> > > > > +void spi_nor_debugfs_shutdown(void)
> > > > > +{
> > > > > +	if (rootdir)
> > > > > +		debugfs_remove(rootdir);   =20
> > > >=20
> > > > debugfs_remove() already has a check for NULL.
> > > >    =20
> > >=20
> > > Ah, good catch, I merged this in when I applied it to my tree, thanks=
! =20
> >=20
> > 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. =20
>=20
> It's been sitting around for a month, I assumed it was lost, so I picked
> it up.

Sorry if it took too long, the merge window also happened during that
time, we are collecting patches now that 6.3-rc1 has been released.
Next time don't hesitate to ping first ;-)

> I can revert it if you don't want me to take it for 6.3-final
> through my driver core tree.

I'll let spi-nor maintainers decide what they prefer.

Thanks,
Miqu=C3=A8l