Re: [PATCH v4 4/6] mm: page_alloc: add alloc_contig_frozen_{range,pages}()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

On 2025/12/18 3:20, Zi Yan wrote:
> On 17 Dec 2025, at 2:17, Kefeng Wang wrote:
> 
>> On 2025/12/17 1:20, Zi Yan wrote:
>>> On 16 Dec 2025, at 6:48, Kefeng Wang wrote:
...
>>>>
>>>> +static void __free_contig_frozen_range(unsigned long pfn, unsigned long nr_pages)
>>>> +{
>>>> +	for (; nr_pages--; pfn++)
>>>> +		free_frozen_pages(pfn_to_page(pfn), 0);
>>>> +}
>>>> +
>>>
>>> Is it possible to use pageblock_order to speed this up?
>>
>> It should be no different since the page order always zero, maybe I
>> didn't get your point.
> 
> Something like but take care of the cases when pfn and nr_pages are
> not aligned to pageblock_nr_pages:
> 
> for (; nr_pages -= pageblock_nr_pages; pfn += pageblock_nr_pages)
> 	free_frozen_pages(pfn_to_page(pfn), pageblock_order);
> 
> It makes fewer calls.

One of the drawbacks I though is that the pages can't be released to PCP
when the pageblock_order != PMD_ORDER, or released to different PCP
list (order-0 vs order-PMD_ORDER).

We maybe optimize it later if it's critical, but I don't want to do it 
in this patchset.

Thanks.