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    SubjectRe: [patch] hugetlb: correct page offset index for sharing pmd
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    On Fri, Aug 10, 2012 at 9:16 PM, Michal Hocko <mhocko@suse.cz> wrote:
    > Subject: [PATCH] hugetlb: do not use vma_hugecache_offset for
    > vma_prio_tree_foreach
    >
    > 0c176d5 (mm: hugetlb: fix pgoff computation when unmapping page
    > from vma) fixed pgoff calculation but it has replaced it by
    > vma_hugecache_offset which is not approapriate for offsets used for
    > vma_prio_tree_foreach because that one expects index in page units
    > rather than in huge_page_shift.
    > Using vma_hugecache_offset is not incorrect because the pgoff will fit
    > into the same vmas but it is confusing.
    >

    Well, how is the patch tested?

    > Cc: Hillf Danton <dhillf@gmail.com>
    > Cc: Mel Gorman <mel@csn.ul.ie>
    > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    > Cc: David Rientjes <rientjes@google.com>
    > Signed-off-by: Michal Hocko <mhocko@suse.cz>
    > ---
    > mm/hugetlb.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)
    >
    > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
    > index c39e4be..a74ea31 100644
    > --- a/mm/hugetlb.c
    > +++ b/mm/hugetlb.c
    > @@ -2462,7 +2462,8 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
    > * from page cache lookup which is in HPAGE_SIZE units.
    > */
    > address = address & huge_page_mask(h);
    > - pgoff = vma_hugecache_offset(h, vma, address);
    > + pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
    > + vma->vm_pgoff;
    > mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
    >
    > /*
    > --
    > 1.7.10.4
    >
    >
    > --
    > Michal Hocko
    > SUSE Labs


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