On Thu, Feb 12, 2015 at 12:53:42PM -0500, Mark Hounschell wrote:
> This happens immediately after unloading one of our out of kernel GPL drivers.
> The driver has done NOTHING other than load at bootup. I'm running a 3.18.7
> kernel (x86_64) on an AMD platform. I can't see anything obviously wrong in
> our
> driver. It works fine when the iommu is disabled. This particular machine has
> 7 of
> our cards in it. Four in one expansion rack and 3 in another. The 2 PCI
> expansion
> racks use pci-e interface cards installed in the MB.
>
> Feb 12 10:47:15 harley kernel: AMD-Vi: Event logged [IO_PAGE_FAULT
> device=0f:00.0 domain=0x0000 address=0x00000000000ae640 flags=0x0070]
> Feb 12 10:47:15 harley kernel: AMD-Vi: Event logged [IO_PAGE_FAULT
> device=0f:00.0 domain=0x0000 address=0x00000000000ae660 flags=0x0070]
> Feb 12 10:47:15 harley kernel: AMD-Vi: Event logged [IO_PAGE_FAULT
> device=0f:00.0 domain=0x0000 address=0x00000000000ae670 flags=0x0070]
> Feb 12 10:47:27 harley kernel: ------------[ cut here ]------------
> Feb 12 10:47:27 harley kernel: WARNING: CPU: 3 PID: 0 at
> drivers/iommu/amd_iommu.c:2637 dma_ops_domain_unmap.part.13+0x65/0x70()
This warning indicates that some driver is unmapping a dma range that
was not mapped previously (meaning that a pte in the io-page-tables is
zeroed out).
The reason for this (and the IO_PAGE_FAULTs) you see are almost
certainly because some driver does not use the DMA-API correctly.
Joerg
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