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

From: Chris Snook
Date: Mon Apr 21 2008 - 14:44:19 EST


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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