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SubjectRe: [PATCH v2] mm: huge_memory: convert split_huge_pages_all() to use a folio
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On 2022/12/31 5:45, Andrew Morton wrote:
> On Fri, 30 Dec 2022 17:30:20 +0800 Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
>> Straightforwardly convert split_huge_pages_all() to use a folio.
>>
>> ...
>>
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -2932,6 +2932,7 @@ static void split_huge_pages_all(void)
>> {
>> struct zone *zone;
>> struct page *page;
>> + struct folio *folio;
>> unsigned long pfn, max_zone_pfn;
>> unsigned long total = 0, split = 0;
>>
>> @@ -2944,24 +2945,32 @@ static void split_huge_pages_all(void)
>> int nr_pages;
>>
>> page = pfn_to_online_page(pfn);
>> - if (!page || !get_page_unless_zero(page))
>> + if (!page || PageTail(page))
>> + continue;
>> + folio = page_folio(page);
>> + if (!folio_try_get(folio))
>> continue;
>>
>> - if (zone != page_zone(page))
>> + if (unlikely(page_folio(page) != folio))
>> + goto next;
>> +
>> + if (zone != folio_zone(folio))
>> goto next;
>
> I'm still not understanding the above hunk. Why is the
> "page_folio(page) != folio" check added? Should it be commented?

There is a comment in try_get_folio(), is it enough?

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