Re: [PATCH v2] mm: thp: Set the accessed flag for old pages onaccess fault.

[Will Deacon]

On Thu, Oct 18, 2012 at 11:05:02PM +0100, Andrew Morton wrote:
> On Wed, 17 Oct 2012 16:54:02 +0100
> Will Deacon <will.deacon@xxxxxxx> wrote:
> 
> > On x86 memory accesses to pages without the ACCESSED flag set result in the
> > ACCESSED flag being set automatically. With the ARM architecture a page access
> > fault is raised instead (and it will continue to be raised until the ACCESSED
> > flag is set for the appropriate PTE/PMD).
> > 
> > For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively
> > setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only
> > be called for a write fault.
> > 
> > This patch ensures that faults on transparent hugepages which do not result
> > in a CoW update the access flags for the faulting pmd.
> 
> Confused.  Where is the arm implementation of update_mmu_cache_pmd()?

Right at the end of this patch, which was posted to the ARM list yesterday:

  http://lists.infradead.org/pipermail/linux-arm-kernel/2012-October/126387.html

Cheers,

Will
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