Re: 2.6.22-rc5: pdflush oops under heavy disk load

[Jay Cliburn]

On Sun, 24 Jun 2007 21:31:36 +0100
"Jay L. T. Cornwall" <jay@xxxxxxxxxxx> wrote:

> Jay Cliburn wrote:
> 
> >> The common factor here seems to be the buffer_head circular list
> >> leading to invalid pointers in bh->b_this_page.
> >>
> >> I'm beginning to suspect the Attansic L1 Gigabit Etherner driver
> >> (marked as EXPERIMENTAL in 2.6.22-rc5). I can't reproduce these
> >> panics on disk-to-disk copies or SCP across the localhost
> >> interface. However, SCP from a server onto either of two different
> >> HDDs hits these oopses fairly quickly.
> 
> > How much RAM is installed in your machine?  If it's 4GB or more,
> > does your problem go away if you boot with mem=3000M?
> 
> Intriguing. Yes, this machine has 4GB of RAM. If I boot with mem=3000M
> the problem does indeed go away - I can't induce an oops even after
> transferring tens of GB across the interface.
> 
> I'm not sure I follow why that would be the case, except that it
> relates to pci_map_page behaviour. But I guess you have an inkling?
> 

For reasons not yet clear to me, it appears the L1 driver has a bug or
the device itself has trouble with DMA in high memory.  This patch,
drafted by Luca Tettamanti, is being explored as a workaround.  I'd be
interested to know if it fixes your problem.

[Aside: For future reference, atl1-devel@xxxxxxxxxxxxxxxxxxxxx is a
mailing list devoted to L1 driver development.]

Jay



diff --git a/drivers/net/atl1/atl1_main.c b/drivers/net/atl1/atl1_main.c
index 6862c11..a600601 100644
--- a/drivers/net/atl1/atl1_main.c
+++ b/drivers/net/atl1/atl1_main.c
@@ -2104,15 +2104,12 @@ static int __devinit atl1_probe(struct pci_dev *pdev,
 	if (err)
 		return err;
 
-	err = pci_set_dma_mask(pdev, DMA_64BIT_MASK);
+	err = pci_set_dma_mask(pdev, DMA_32BIT_MASK);
 	if (err) {
-		err = pci_set_dma_mask(pdev, DMA_32BIT_MASK);
-		if (err) {
-			dev_err(&pdev->dev, "no usable DMA configuration\n");
-			goto err_dma;
-		}
-		pci_using_64 = false;
+		dev_err(&pdev->dev, "no usable DMA configuration\n");
+		goto err_dma;
 	}
+	pci_using_64 = false;
 	/* Mark all PCI regions associated with PCI device
 	 * pdev as being reserved by owner atl1_driver_name
 	 */

-
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