On Fri 03-08-12 20:56:45, Hillf Danton wrote:
> The computation of page offset index is open coded, and incorrect, to
> be used in scanning prio tree, as huge page offset is required, and is
> fixed with the well defined routine.
I guess that nobody reported this because if someone really wants to
share he will use aligned address for mmap/shmat and so the index is 0.
Anyway it is worth fixing. Thanks for pointing out!
>
> Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
> ---
>
> --- 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
> @@ -72,12 +72,15 @@ static void huge_pmd_share(struct mm_str
> if (!vma_shareable(vma, addr))
> return;
>
> + idx = linear_page_index(vma, addr);
> +
You can use linear_hugepage_index directly and remove the idx
initialization as well.
> mutex_lock(&mapping->i_mmap_mutex);
> vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
> if (svma == vma)
> continue;
>
> - saddr = page_table_shareable(svma, vma, addr, idx);
> + saddr = page_table_shareable(svma, vma, addr,
> + idx * (PMD_SIZE/PAGE_SIZE));
Why not just fixing page_table_shareable as well rather than playing
tricks like this?
> if (saddr) {
> spte = huge_pte_offset(svma->vm_mm, saddr);
> if (spte) {
> --
--
Michal Hocko
SUSE Labs
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