Re: kernel BUG at drivers/iommu/intel-iommu.c:1767 on F16 3.1.1-2.fc16.x86_64

[Albert Strasheim]

Hello

On Thu, Dec 8, 2011 at 7:47 PM, Roland Dreier <roland@xxxxxxxxxxxxxxx> wrote:
>  > [  597.412843] kernel BUG at drivers/iommu/intel-iommu.c:1767!
> So this is
>        BUG_ON(addr_width < BITS_PER_LONG && (iov_pfn + nr_pages - 1)
>>> addr_width);
>
> in __domain_mapping() I believe.  And we have:
>        int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT;
> How much RAM does you system have?

192 GB.

A few gigabyte is reserved for 2 MB huge pages, if that matters.

> I don't know too much about the low-level VT-d details, but is it
> possible the setup code
> is choosing a too small "guest address width" to cover all your memory?
>
> drivers/net/ethernet/mellanox/mlx4/main.c has
>
>        err = pci_set_dma_mask(pdev, DMA_BIT_MASK(64));
>        if (err) {
>                dev_warn(&pdev->dev, "Warning: couldn't set 64-bit PCI
> DMA mask.\n");
>                err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
>                if (err) {
>                        dev_err(&pdev->dev, "Can't set PCI DMA mask,
> aborting.\n");
>                        goto err_release_regions;
>                }
>        }
>        err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64));
>        if (err) {
>                dev_warn(&pdev->dev, "Warning: couldn't set 64-bit "
>                         "consistent PCI DMA mask.\n");
>                err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32));
>                if (err) {
>                        dev_err(&pdev->dev, "Can't set consistent PCI
> DMA mask, "
>                                "aborting.\n");
>                        goto err_release_regions;
>                }
>        }
>
> do you see any warnings in your kernel log about setting the PCI DMA mask?
> (in any case that should only affect bus addresses, not "guest addresses")

I don't see anything like what you mentioned here.

>From the SAS controller:

mpt2sas0: 64 BIT PCI BUS DMA ADDRESSING SUPPORTED, total mem (198141716 kB)

Not seeing anything about PCI DMA errors.

I think the BIOS has VT-d enabled. dmesg says:

PCI-DMA: Intel(R) Virtualization Technology for Directed I/O

I can send you a full dmesg if that would help.

Regards

Albert
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