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    SubjectRe: [PATCH 04/10] hugetlb: hugepage migration core
    On Wed, Sep 22, 2010 at 01:59:07PM +0900, Naoya Horiguchi wrote:
    > On Mon, Sep 20, 2010 at 12:10:55PM +0100, Mel Gorman wrote:
    > > On Wed, Sep 08, 2010 at 10:19:35AM +0900, Naoya Horiguchi wrote:
    > ...
    > > > @@ -95,26 +96,34 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
    > > > pte_t *ptep, pte;
    > > > spinlock_t *ptl;
    > > >
    > > > - pgd = pgd_offset(mm, addr);
    > > > - if (!pgd_present(*pgd))
    > > > - goto out;
    > > > + if (unlikely(PageHuge(new))) {
    > > > + ptep = huge_pte_offset(mm, addr);
    > > > + if (!ptep)
    > > > + goto out;
    > > > + ptl = &mm->page_table_lock;
    > > > + } else {
    > > > + pgd = pgd_offset(mm, addr);
    > > > + if (!pgd_present(*pgd))
    > > > + goto out;
    > > >
    > > > - pud = pud_offset(pgd, addr);
    > > > - if (!pud_present(*pud))
    > > > - goto out;
    > > > + pud = pud_offset(pgd, addr);
    > > > + if (!pud_present(*pud))
    > > > + goto out;
    > > >
    > >
    > > Why are the changes to teh rest of the walkers necessary? Instead, why
    > > did you not identify which PTL lock you needed and then goto the point
    > > where spin_lock(ptl) is called? Similar to what page_check_address()
    > > does for example.
    >
    > This is because Andi-san commented to avoid using goto sentense.
    > But honestly I'm not sure which is a clear way.
    >

    Ok, personally I would prefer to have matched page_check_address() so we use
    similar code patterns when the intention is the same but as functionally it
    seems fine, I'm not going to fight over it either.

    Thanks.

    --
    Mel Gorman
    Part-time Phd Student Linux Technology Center
    University of Limerick IBM Dublin Software Lab


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