Messages in this thread | | | Date | Wed, 1 Apr 2015 16:19:07 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCHv4 19/24] thp, mm: use migration entries to freeze page counts on split |
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On Mon, Mar 30, 2015 at 09:15:47PM +0530, Aneesh Kumar K.V wrote: > "Kirill A. Shutemov" <kirill@shutemov.name> writes: > > > On Mon, Mar 30, 2015 at 08:38:08PM +0530, Aneesh Kumar K.V wrote: > >> .... > >> .... > >> +static void freeze_page(struct anon_vma *anon_vma, struct page *page) > >> > +{ > >> > + struct anon_vma_chain *avc; > >> > + struct vm_area_struct *vma; > >> > + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); > >> > >> So this get called only with head page, We also do > >> BUG_ON(PageTail(page)) in the caller. But > >> > >> > >> > + unsigned long addr, haddr; > >> > + unsigned long mmun_start, mmun_end; > >> > + pgd_t *pgd; > >> > + pud_t *pud; > >> > + pmd_t *pmd; > >> > + pte_t *start_pte, *pte; > >> > + spinlock_t *ptl; > >> ...... > >> > >> > >> > + > >> > +static void unfreeze_page(struct anon_vma *anon_vma, struct page *page) > >> > +{ > >> > + struct anon_vma_chain *avc; > >> > + pgoff_t pgoff = page_to_pgoff(page); > >> > >> Why ? Can this get called for tail pages ? > > > > It cannot. pgoff is offset of head page (and therefore whole compound > > page) within rmapping. > > > > This we can use > > pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); > > similar to what we do in freeze_page(). The difference between > freeze/unfreeze confused me.
Fair enough. Will fix.
-- Kirill A. Shutemov
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