Re: atl1 64-bit => 32-bit DMA borkage (reproducible, bisected)

[Chris Snook]

Alexey Dobriyan wrote:
> On Sun, Apr 20, 2008 at 01:37:04PM -0500, Jay Cliburn wrote:
> > On Sun, 20 Apr 2008 16:26:31 +0400
> > Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> >
> > > On Sun, Apr 20, 2008 at 06:06:07AM -0500, Jay Cliburn wrote:
> > > > On Sun, 20 Apr 2008 15:14:53 +0400
> > > > Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> > > >
> > > > > On Sat, Apr 19, 2008 at 09:54:44PM -0500, Jay Cliburn wrote:
> > > > > > On Sat, 19 Apr 2008 18:45:35 +0400
> > > > > > Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> > [...]
> > > > > > > So, it's enough to scp 200 MB git archive and immediately
> > > > > > > start rebooting sequence for horrors described above to
> > > > > > > appear. It's not 100% reproducible but more like 90%.
> > > > > > Do I understand correctly that these failures occur only while
> > > > > > the network interface is going down?
> > > > > Yep. During up or running there were no problems with this card.
> > > > One more question:  Does it happen whether or not you're using atl1
> > > > as a netconsole?
> > > Without netconsole bugs happens too.
> > I can't duplicate this error, but it's probably because my machine
> > doesn't have 4GB of memory.
> >
> > I have one report in Febroary 2008 of another user encountering strange
> > oopses in 2.6.23.12 and 2.6.24 whenever he downed the interface.  I
> > suspect your experience is a repeat of that.
> >
> > Just to be clear, you transfer about 200MB to the NIC (Rx direction),
> > then immediately reboot, right?
>
> Yup!
>
> > Can you duplicate the problem if you
> > simply ifconfig down instead of rebooting after the transfer?  
>
> Aha, ifconfig down is enough. Here is how reproducer looks like now:
>
> 	./sync-linux-linus && ssh core2 "sudo /sbin/ifconfig eth0 down"
>
> where first script is basically scp(1).
>
> Also, booting with 1G or 2G of RAM (mem=1024m) makes issue go away.
>
> printk at dev_close() time shows that NETIF_F_HIGHDMA was not somehow
> enabled.

Does the problem go away with iommu=nomerge?  If so, I suspect we're not 
properly flushing an iowrite somewhere.

-- Chris
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