Messages in this thread | | | Date | Fri, 15 May 2015 14:01:40 +0200 | From | Vlastimil Babka <> | Subject | Re: [PATCHv5 05/28] mm: adjust FOLL_SPLIT for new refcounting |
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On 05/15/2015 01:36 PM, Kirill A. Shutemov wrote: > On Fri, May 15, 2015 at 01:05:27PM +0200, Vlastimil Babka wrote: >> On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote: >>> We need to prepare kernel to allow transhuge pages to be mapped with >>> ptes too. We need to handle FOLL_SPLIT in follow_page_pte(). >>> >>> Also we use split_huge_page() directly instead of split_huge_page_pmd(). >>> split_huge_page_pmd() will gone. >> >> You still call split_huge_page_pmd() for the is_huge_zero_page(page) case. > > For huge zero page we split PMD into table of zero pages and don't touch > compound page under it. That's what split_huge_page_pmd() (renamed into > split_huge_pmd()) will do by the end of patchset.
Ah, I see.
>> Also, of the code around split_huge_page() you basically took from >> split_huge_page_pmd() and open-coded into follow_page_mask(), you didn't >> include the mmu notifier calls. Why are they needed in split_huge_page_pmd() >> but not here? > > We do need mmu notifier in split_huge_page_pmd() for huge zero page. When
Oh, I guess that's obvious then... to someone, anyway. Thanks.
In that case the patch seems fine.
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> we need to split compound page we go into split_huge_page() which takes > care about mmut notifiers. >
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