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SubjectRe: [patch v2] hugetlb: correct page offset index for sharing pmd
On Sat 04-08-12 14:08:31, Hillf Danton wrote:
> The computation of page offset index is incorrect to be used in scanning
> prio tree, as huge page offset is required, and is fixed with well
> defined routine.
>
> Changes from v1
> o s/linear_page_index/linear_hugepage_index/ for clearer code
> o hp_idx variable added for less change
>
>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> ---
>
> --- a/arch/x86/mm/hugetlbpage.c Fri Aug 3 20:34:58 2012
> +++ b/arch/x86/mm/hugetlbpage.c Fri Aug 3 20:40:16 2012
> @@ -62,6 +62,7 @@ static void huge_pmd_share(struct mm_str
> {
> struct vm_area_struct *vma = find_vma(mm, addr);
> struct address_space *mapping = vma->vm_file->f_mapping;
> + pgoff_t hp_idx;
> pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
> vma->vm_pgoff;

So we have two indexes now. That is just plain ugly!

> struct prio_tree_iter iter;
> @@ -72,8 +73,10 @@ static void huge_pmd_share(struct mm_str
> if (!vma_shareable(vma, addr))
> return;
>
> + hp_idx = linear_hugepage_index(vma, addr);
> +
> mutex_lock(&mapping->i_mmap_mutex);
> - vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
> + vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, hp_idx, hp_idx) {
> if (svma == vma)
> continue;
>
> --

--
Michal Hocko
SUSE Labs


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