Re: iwlwifi warn_slowpath with 3.*

[Antonio Quartulli <ordex@autistici.org>]

[-- Attachment #1: Type: text/plain, Size: 2595 bytes --]

On Tue, May 01, 2012 at 08:34:15PM +0200, Antonio Quartulli wrote:
> On Tue, May 01, 2012 at 08:13:46PM +0300, Emmanuel Grumbach wrote:
> > Hi,
> > 
> > I am not sure the patch will help because the race is _very_ unlikely.
> > But I would be glad to know if you can reproduce on latest
> > compat-wireless.
> > How reproducible is that on 3.3.3 ? Is that 100% ?
> 
> it seems so. It happens at least once at boot time.
> I will try wireless-testing and see what happens. Then I will apply your patch.

The problem is there either with wireless-testing and with
wireless-testing+your_patch.

If it can somehow help, I also got several stack trace regarding intel_iova
functions. But then the I got kernel panic and I was not able to copy the
messages.



Thanks

> > 
> > I guess my machine doesn't have IOMMU, but honestly, I am not sure I
> > know how to check.
> > 
> > On Tue, May 1, 2012 at 19:52, Venkataraman, Meenakshi
> > <meenakshi.venkataraman@intel.com> wrote:
> > >
> > > Hi John, Antonio,
> > >
> > > Emmanuel found a race condition in rx buffer allocation/deallocation, and
> > > attached is a patch that fixes it.
> > >
> > > >> > since linux-3.0 (I don't remember if it was the case even before),
> > > >> > I'm getting this output in dmesg:
> > > >> >
> > > >> > [   53.662990] ------------[ cut here ]------------
> > > >> > [   53.663016] WARNING: at drivers/iommu/intel-iommu.c:2911
> > > >> > intel_unmap_page+0x14b/0x180()
> > > >> > [   53.663047] Hardware name: Latitude E5420
> > > >> > [   53.663066] Driver unmaps unmatched page at PFN ffd1a000
> > > >>
> > > >>
> > > >> I see that I always get the same addr passed to the unmap function:
> > > >>
> > > >> [   23.950535] Driver unmaps unmatched page at PFN ffd1a000
> > > >>
> > > >> is it a coincidence?
> > > >> I'm running linux-3.3.3 right now. I can try wireless-testing if it
> > > >> would help.
> > >
> > > [MV] Antonio -- can you try out the patch attached and let us know if you
> > > continue to see the problem?
> > >
> > > >Just for the record, we are seeing a similar problem on RHEL 6.3 (which
> > > > has an
> > > >iwlwifi driver derived from linux-3.2).
> > > >
> > > >       https://bugzilla.redhat.com/show_bug.cgi?id=815998
> > >
> > > [MV] John -- I'll update the redhat bugzilla as well.
> > >
> > > Thanks
> > > Meenakshi
> 
> -- 
> Antonio Quartulli
> 
> ..each of us alone is worth nothing..
> Ernesto "Che" Guevara



-- 
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

[-- Attachment #2: Type: application/pgp-signature, Size: 490 bytes --]