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SubjectRe: x86/mm/pageattr: Code without effect?
On Mon, Apr 08, 2013 at 03:10:00PM +0200, Stefan Bader wrote:
> * that we limited the number of possible pages already to
> * the number of pages in the large page.
> */
> if (address == (address & pmask) && cpa->numpages == (psize >>
> PAGE_SHIFT)) {
> /*
> * The address is aligned and the number of pages
> * covers the full page.
> */
> new_pte = pfn_pte(pte_pfn(old_pte), new_prot);
> ^
>
> This one. The first patch changed
>
> - new_pte = pfn_pte(pte_pfn(old_pte), canon_pgprot(new_prot));
> + new_pte = pfn_pte(pte_pfn(old_pte), new_prot);
>
> The fixup patch drops new_prot completely from being initialized and only works
> on req_prot. Probably it would be best to also drop the definition of new_prot.
> I think it then completely unused.

Actually, we do need and initialize new_prot at line 495:

pfn = pte_pfn(old_pte) + ((address & (psize - 1)) >> PAGE_SHIFT);
cpa->pfn = pfn;

new_prot = static_protections(req_prot, address, pfn); <---

and we need it for the subsequent loop where we go over the 512 PTEs to
decide whether to split or not.

So it is needed after all, AFAICT.

--
Regards/Gruss,
Boris.

Sent from a fat crate under my desk. Formatting is fine.
--


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