Messages in this thread |  | | Date | Mon, 8 Feb 2021 17:02:59 -0500 | From | Peter Xu <> | Subject | Re: [PATCH 0/2] KVM: do not assume PTE is writable after follow_pfn |
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On Mon, Feb 08, 2021 at 02:51:33PM -0400, Jason Gunthorpe wrote: > On Fri, Feb 05, 2021 at 01:14:11PM -0500, Peter Xu wrote: > > > But I do have a question on why dax as the only user needs to pass in the > > notifier to follow_pte() for initialization. > > Not sure either, why does DAX opencode something very much like > page_mkclean() with dax_entry_mkclean()? > > Also it looks like DAX uses the wrong notifier, it calls > MMU_NOTIFY_CLEAR but page_mkclean_one() uses > MMU_NOTIFY_PROTECTION_PAGE for the same PTE modification sequence?? > > page_mkclean() has some technique to make the notifier have the right > size without becoming entangled in the PTL locks..
Right. I guess it's because dax doesn't have "struct page*" on the back, so it can't directly use page_mkclean(). However the whole logic does look very similar, so maybe they can be merged in some way.
Thanks,
-- Peter Xu
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