Messages in this thread | | | Date | Fri, 3 Aug 2012 15:32:35 +0200 | From | Michal Hocko <> | Subject | Re: [patch] hugetlb: correct page offset index for sharing pmd |
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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@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 > @@ -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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