Re: kmemleak report on isp1763 and sierra MC8705

[Johan Hovold <jhovold@gmail.com>]

On Wed, Nov 14, 2012 at 12:12:01PM -0500, Richard Retanubun wrote:
> On 10/11/12 09:30 AM, Johan Hovold wrote:
> Hi Johan,
> 
> > There was a reference-count fix for the probe error path that went in to
> > v3.5. Haven't read all the details on how you trigger your leak, but at
> > the face of it, it could be related.
> >
> > Have a look at 0658a3366db7e27fa ("usb: use usb_serial_put in
> > usb_serial_probe errors). If related, you should be seeing "Ignoring
> > blacklisted interface #n" messages when you enable debug (e.g. #define
> > DEBUG) in the sierra driver.
> 
> That was it! Thanks so much for the research.
> I can apply it cleanly to 3.0.22 and see usb_release_dev() being
> called and thus no more kmemleak.
> 
> >
> > Greg, it seems to me that the fix referred to above should be backported
> > to the earlier stable trees either way.
> I would vote "yes" for this also.
> 
> While my setup circumstances may be a corner case, (modem kept
> resetting to re-establish PPP connection) it was leaking 1192 bytes
> per occurrence.

The leak affects every failed probe, for example due to blacklisted
interfaces which is quite common, so commit 0658a3366db7 ("usb: use
usb_serial_put in usb_serial_probe errors) should be backported to the
<= 3.4 stable trees.

Thanks for reporting,
Johan