Re: agp: two-stage page destruction issue

From: Jan Beulich
Date: Thu Jun 19 2008 - 05:46:20 EST


>>> "Dave Airlie" <airlied@xxxxxxxxx> 19.06.08 01:57 >>>
>On Wed, Jun 18, 2008 at 6:28 PM, Jan Beulich <jbeulich@xxxxxxxxxx> wrote:
>> Dave,
>>
>> besides it apparently being useful only in 2.6.24 (the changes in 2.6.25
>> really mean that it could be converted back to a single-stage mechanism),
>> I'm seeing an issue in Xen Dom0 kernels, which is caused by the calling
>> of gart_to_virt() in the second stage invocations of the destroy function.
>> I think that besides this being a real issue with Xen (where
>> unmap_page_from_agp() is not just a page table attribute change), this
>> also is invalid from a theoretical perspective: One should not assume that
>> gart_to_virt() is still valid after unmapping a page. So minimally (keeping
>> the 2-stage mechanism) a patch like the one below would be needed.
>>
>
>Looks good to me, its the simpler change for 2.6.26 at this point.
>
>Dave.

So if you're considering it even for 2.6.26, will you push it to Linus? That's
how I understand the process would generally work, or should I push it
in this case (in which case it might be good to know whether your above
statement should be translated into an Acked-by or Signed-off-by)?

Thanks, Jan

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