On Thu, May 20, 2021 at 12:24 PM Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, 20 May 2021 10:59:49 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote:
>
> > Since commit d6995da31122 ("hugetlb: use page.private for hugetlb specific
> > page flags") converts page.private for hugetlb specific page flags. We
> > should use hugetlb_page_subpool() to get the subpool pointer instead of
> > page_private(). The commit forgot to update it in the page migration
> > routine. So fix it.
> >
> > ...
> >
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -1290,7 +1290,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
> > * page_mapping() set, hugetlbfs specific move page routine will not
> > * be called and we could leak usage counts for subpools.
> > */
> > - if (page_private(hpage) && !page_mapping(hpage)) {
> > + if (hugetlb_page_subpool(hpage) && !page_mapping(hpage)) {
> > rc = -EBUSY;
> > goto out_unlock;
> > }
>
> So it uses the wrong page*, so this isn't just a cosmetic fix. One
> cannot tell from this changelog.
>
> Please describe the runtime effects of this bug. Please always include
> this information when fixing bugs. And when adding them.
OK. I should update the commit log in the next version.
Thanks.
