On 11/10/2010 09:16 PM, Andi Kleen wrote:
On Wed, Nov 10, 2010 at 07:47:11PM +0200, Avi Kivity wrote:
> On 11/10/2010 07:44 PM, Andi Kleen wrote:
> >> Doing it in userspace in easier, since we can replace the vma for
> >> that section (and avoid mixed 4k/2M pages in hugetlbfs).
> >
> >You can't do that today, there's no way currently to access the non corrupted
> >portion of the 2MB page. Once it's poisoned it's all gone.
>
> I see. Thanks.
BTW my understanding is that KVM will only use hugepages with
transparent huge pages anyways, correct?
There will always be those who want full control over every last bit;
they will use hugetlbfs and numactl for manual allocation of resources
for guests.
General usage will be with transparent huge pages, though.
So it may be reasonable to simply fix this as part of the transparent
hugepages work, but ignore it before that.
Transparent hugepages work only for anonymous memory.
However, hugetlbfs is not the only option for backing -mempath memory;
if poisoning works for tmpfs/shm or other file backed memory, we can use
that to get named access to memory.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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