On Fri, Nov 25, 2016 at 05:57:20PM +0530, Anshuman Khandual wrote:
> On 11/08/2016 05:01 AM, Naoya Horiguchi wrote:
...
> > @@ -497,30 +541,15 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned
> > long addr,
> > struct page *page;
> > struct queue_pages *qp = walk->private;
> > unsigned long flags = qp->flags;
> > - int nid, ret;
> > + int ret;
> > pte_t *pte;
> > spinlock_t *ptl;
> >
> > - if (pmd_trans_huge(*pmd)) {
> > - ptl = pmd_lock(walk->mm, pmd);
> > - if (pmd_trans_huge(*pmd)) {
> > - page = pmd_page(*pmd);
> > - if (is_huge_zero_page(page)) {
> > - spin_unlock(ptl);
> > - __split_huge_pmd(vma, pmd, addr, false, NULL);
> > - } else {
> > - get_page(page);
> > - spin_unlock(ptl);
> > - lock_page(page);
> > - ret = split_huge_page(page);
> > - unlock_page(page);
> > - put_page(page);
> > - if (ret)
> > - return 0;
> > - }
> > - } else {
> > - spin_unlock(ptl);
> > - }
> > + ptl = pmd_trans_huge_lock(pmd, vma);
> > + if (ptl) {
> > + ret = queue_pages_pmd(pmd, ptl, addr, end, walk);
> > + if (ret)
> > + return 0;
> > }
>
> I wonder if we should introduce pte_entry function along with pmd_entry
> function as we are first looking for trans huge PMDs either for direct
> addition into the migration list or splitting it before looking for PTEs.
Most of pagewalk users don't define pte_entry because of performance reason
(to avoid the overhead of PTRS_PER_PMD function calls).
But that could be a nice cleanup if we have a workaround.
Thanks,
Naoya Horiguchi
