Re: [dm-devel] AMD-Vi IO_PAGE_FAULTs and ata3.00: failed command: READ FPDMA QUEUED errors since Linux 4.0

[Andreas Hartmann <andihartmann-KuiJ5kEpwI6ELgA04lAiVw@public.gmane.org>]

On 09/29/2015 at 06:20 PM, Joerg Roedel wrote:
> On Tue, Sep 29, 2015 at 11:58:10AM -0400, Mikulas Patocka wrote:
>> On Tue, 29 Sep 2015, Joerg Roedel wrote:
>> There was a patch (34b48db66e08ca1c1bc07cf305d672ac940268dc) that 
>> increased default block request size. That patch triggers AMD-Vi page 
>> faults. The bug may be in ATA driver, in ATA controller on in AMD-Vi 
>> driver or hardware. I didn't see anything in that thread that proves that 
>> the bug in not in AMD-Vi IOMMU.
>>
>> The bug probably existed even before kernel 3.19, but it was masked by the 
>> fact that I/O request size was artifically capped. Bisecting probably 
>> won't find it, as it may have existed since ever.
> 
> Okay, I see. But as long as the request-size is not bigger than 128MB
> (the biggest chunk the AMD IOMMU driver can map at once), I don't see
> how the IOMMU driver could be at fault.
> 
> Which ATA driver is in use when this happens and are there instructions
> on how to reproduce the issue?
> 
> Alternativly someone who can reproduce it should trace the calls to
> __map_single and __unmap_single in the AMD IOMMU driver to find out
> whether the addresses which the faults happen on are really mapped, or
> at least requested from the AMD IOMMU driver.

How can I trace it?


Thanks,
Andreas