Re: [RFC PATCH 0/5] Use an alternative to _PAGE_PROTNONE for _PAGE_NUMA v2

From: Peter Zijlstra
Date: Tue Apr 08 2014 - 13:30:53 EST


On Tue, Apr 08, 2014 at 05:46:52PM +0100, Mel Gorman wrote:
> Someone will ask why automatic NUMA balancing hints do not use "real"
> PROT_NONE but as it would need VMA information to do that on all
> architectures it would mean that VMA-fixups would be required when marking
> PTEs for NUMA hinting faults so would be expensive.

Like this:

https://lkml.org/lkml/2012/11/13/431

That used the generic PROT_NONE infrastructure and compared, on fault,
the page protection bits against the vma->vm_page_prot bits?

So the objection to that approach was the vma-> dereference in
pte_numa() ?
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