Re: [PATCHv4 19/24] thp, mm: use migration entries to freeze page counts on split

[Aneesh Kumar K.V]

....
....
 +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 ?


-aneesh

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