Re: [RFC PATCH 1/5] mm: intorduce __GFP_UNMAPPED and unmapped_alloc()

["Edgecombe, Rick P" <rick.p.edgecombe@intel.com>]

On Wed, 2023-03-08 at 11:41 +0200, Mike Rapoport wrote:
> +
> +static inline void __free_one_page(struct page *page, unsigned int
> order,
> +                                  bool cache_refill)
> +{
> +       unsigned long pfn = page_to_pfn(page);
> +       unsigned long buddy_pfn;
> +       unsigned long combined_pfn;
> +       struct page *buddy;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&free_area->lock, flags);
> +
> +       if (cache_refill) {
> +               set_pageblock_unmapped(page);
> +               free_area[order].nr_cached++;
> +       }
> +
> +       while (order < MAX_ORDER - 1) {
> +               buddy = find_unmapped_buddy_page_pfn(page, pfn,
> order,
> +                                                    &buddy_pfn);
> +               if (!buddy)
> +                       break;
> +
> +               del_page_from_free_list(buddy, order);
> +               combined_pfn = buddy_pfn & pfn;
> +               page = page + (combined_pfn - pfn);
> +               pfn = combined_pfn;
> +               order++;
> +       }
> +
> +       set_unmapped_order(page, order);
> +       add_to_free_list(page, order);
> +       spin_unlock_irqrestore(&free_area->lock, flags);
> +}
> +

The page has to be zeroed before it goes back on the list, right? I
didn't see it.