On Wed, 14 Sep 2022 10:23:05 -0700 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote:
> On 09/13/22 12:54, Doug Berger wrote:
> > When demoting a hugepage to a smaller order, the number of pages
> > added to the target hstate will be the size of the large page
> > divided by the size of the smaller page.
> >
> > Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support")
> > Signed-off-by: Doug Berger <opendmb@xxxxxxxxx>
> > ---
> > mm/hugetlb.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index e070b8593b37..79949893ac12 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -3472,7 +3472,8 @@ static int demote_free_huge_page(struct hstate *h, struct page *page)
> > * based on pool changes for the demoted page.
> > */
> > h->max_huge_pages--;
> > - target_hstate->max_huge_pages += pages_per_huge_page(h);
> > + target_hstate->max_huge_pages += pages_per_huge_page(h) /
> > + pages_per_huge_page(target_hstate);
> >
> > return rc;
> > }
>
> This has already been fixed here,
>
> https://lore.kernel.org/linux-mm/20220823030209.57434-2-linmiaohe@xxxxxxxxxx/
Neither version tells us the user-visible runtime effects of the change :(
