Re: [PATCH] hugetlb: do not use vma_hugecache_offset for vma_prio_tree_foreach

[Michal Hocko <mhocko@suse.cz>]

On Thu 16-08-12 20:45:15, Hillf Danton wrote:
> On Mon, Aug 13, 2012 at 9:55 PM, Michal Hocko <mhocko@suse.cz> wrote:
> > 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 so the standard PAGE_SHIFT based
> > index calculation is used instead.
> >
> > Cc: Hillf Danton <dhillf@gmail.com>
> > Cc: Mel Gorman <mel@csn.ul.ie>
> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > Cc: Andrea Arcangeli <aarcange@redhat.com>
> > Cc: David Rientjes <rientjes@google.com>
> > Signed-off-by: Michal Hocko <mhocko@suse.cz>
> > ---
> 
> Thanks
> 
> Acked-by: Hillf Danton <dhillf@gmail.com>

Thanks Hillf!

> >  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