Re: [External] Re: [PATCH v23 6/9] mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page

[Muchun Song <songmuchun@bytedance.com>]

On Mon, May 10, 2021 at 6:45 PM Oscar Salvador <osalvador@suse.de> wrote:
>
> On Mon, May 10, 2021 at 11:00:24AM +0800, Muchun Song wrote:
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1376,6 +1376,39 @@ static void remove_hugetlb_page(struct hstate *h, struct page *page,
> >       h->nr_huge_pages_node[nid]--;
> >  }
> >
> > +static void add_hugetlb_page(struct hstate *h, struct page *page,
> > +                          bool adjust_surplus)
> > +{
> > +     int zeroed;
> > +     int nid = page_to_nid(page);
> > +
> > +     VM_BUG_ON_PAGE(!HPageVmemmapOptimized(page), page);
> > +
> > +     lockdep_assert_held(&hugetlb_lock);
> > +
> > +     INIT_LIST_HEAD(&page->lru);
> > +     h->nr_huge_pages++;
> > +     h->nr_huge_pages_node[nid]++;
> > +
> > +     if (adjust_surplus) {
> > +             h->surplus_huge_pages++;
> > +             h->surplus_huge_pages_node[nid]++;
> > +     }
> > +
> > +     set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
> > +     set_page_private(page, 0);
>
> I think this has already been discused, so sorry about this.
>
> The only reason to need the set_page_private() is because of the dissolving
> function right? add_hugetlb_page() can only get reached via free_huge_page(),
> or dissolve_free_huge_page, and while the former clears the flags, the latter
> it does not.

Not exactly right. free_huge_page() does not clear HPageTemporary
if the page is temporarily allocated when freeing. You are right that
dissolve_free_huge_page() does not clear HPageFreed.

>
> I think this function would benefit from some renaming. add_hugetlb_page() gives
> me no hint of what is this about, although I can figure it out reading the code.

Because I think it is the reverse operation of remove_hugetlb_page,
I named it add_hugetlb_page. Do you have any suggestions for
renaming?

Thanks.

>
> With that: Reviewed-by: Oscar Salvador <osalvador@suse.de>
>
>
>
>
> --
> Oscar Salvador
> SUSE L3