linux-kernel - Re: kmemleak reports firmware loader funnies in iwlwifi

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Message-Id: <1246286036.21450.35.camel@pc1117.cambridge.arm.com>
Date:	Mon, 29 Jun 2009 15:33:56 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Dave Jones <davej@...hat.com>, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: kmemleak reports firmware loader funnies in iwlwifi

On Mon, 2009-06-29 at 12:48 +0300, Pekka Enberg wrote:
> Hi Catalin,
> 
> On Mon, Jun 29, 2009 at 12:39 PM, Catalin
> Marinas<catalin.marinas@....com> wrote:
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index ddeb819..26fb808 100644
> > --- a/drivers/base/firmware_class.c
> > +++ b/drivers/base/firmware_class.c
> > @@ -179,6 +179,13 @@ static ssize_t firmware_loading_store(struct device *dev,
> >                                dev_err(dev, "%s: vmap() failed\n", __func__);
> >                                goto err;
> >                        }
> > +                       /*
> > +                        * This block of memory is later freed using vfree.
> > +                        * Since kmemleak does not track vmap calls, just
> > +                        * inform it about this block but ignore it during
> > +                        * scanning.
> > +                        */
> > +                       kmemleak_alloc(fw_priv->fw->data, 0, -1, GFP_KERNEL);
> >                        /* Pages will be freed by vfree() */
> >                        fw_priv->pages = NULL;
> >                        fw_priv->page_array_size = 0;
> 
> Would it be possible to put this hook in vmap() somehow?

I tried to do this but it has some other implications. If I add the vmap
hook, I would need to add vunmap as well. On ARM, at least, iounmap
calls vunmap (but not vmap) which means that I would need to add ioremap
support as well. That's not a bug issue but this is more like a new
feature than a bug fix.

I propose that for now I disable the kmemleak warning for unknown
pointers and add a patch to linux-next which tracks ioremap and vmap
mappings. Does this sound fine?

Thanks.

-- 
Catalin

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