Re: sata_nv frees DMA memory with different size (possibly a generic libata bug)

[Robert Hancock <hancockrwd@gmail.com>]

FUJITA Tomonori wrote:
> On Wed, 18 Feb 2009 17:05:44 -0500
> Chuck Ebbert <cebbert@redhat.com> wrote:
> 
>> On Wed, 18 Feb 2009 15:25:16 -0500
>> Chuck Ebbert <cebbert@redhat.com> wrote:
>>
>>> On Tue, 17 Feb 2009 20:22:05 +0900
>>> FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote:
>>>
>>>  
>>>>>>>> sata_nv 0000:00:0d.0: DMA-API: device driver frees DMA memory with different
>>>>>>>> size [device address=0x00000000da031000] [map size=4096 bytes] [unmap
>>>>>>> That's rather curious. It seems to be saying that the sg length is 
>>>>>>> different between the map and unmap, but it doesn't look like sata_nv 
>>>>>>> mucks with that anywhere, and neither does libata core..
>>>>>> Could the SCSI code have merged two requests?
>>>>> I wouldn't think so.. and if it did it seems like it would have to have 
>>>>> changed the list after libata got the request somehow..
>>>> Does this box uses GART IOMMU?
>>> I don't think so, but I've asked for the dmesg.
>> Okay, it _is_ using GART IOMMU:
>>
>> DMA-API: preallocated 8192 debug entries
>> DMA-API: debugging enabled by kernel config
>> PCI-DMA: Disabling AGP.
>> PCI-DMA: aperture base @ 20000000 size 65536 KB
>> PCI-DMA: using GART IOMMU.
>> PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture
> 
> Thanks, that makes sense.
> 
> I think that the following patch could fix this:
> 
> http://marc.info/?l=linux-ide&m=123484533504307&w=2

The patch looks reasonable to me. I'm CCing the reporter of the bug. 
Wes, would you be able to test out Fujita's patch linked above?