On Tue, Apr 8, 2014 at 10:30 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > 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() ? So the important thing is that as long as it works exactly like PROT_NONE as far as hardware (and that includes paravirtualized setups too!) then I guess we should be ok. But that "pte_numa()" does make me go "Hmm.. but does it?". If virtual environments have to look at the vma in order to look at page tables, that's not possible. They have to be able to work with the page tables on their own, _without_ any special rules that are private to the guest. So I'm not seeing any *use* of pte_numa() in places that would make me worry, though. So maybe it works. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>