Re: [PATCH v2 5/5] mm: memory_hotplug: unify Huge/LRU/non-LRU movable folio isolation

[David Hildenbrand <david@redhat.com>]

On 17.08.24 10:49, Kefeng Wang wrote:
> Use the isolate_folio_to_list() to unify hugetlb/LRU/non-LRU
> folio isolation, which cleanup code a bit and save a few calls
> to compound_head().
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>   mm/memory_hotplug.c | 45 +++++++++++++++++----------------------------
>   1 file changed, 17 insertions(+), 28 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 02a0d4fbc3fe..cc9c16db2f8c 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1773,14 +1773,14 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
>   static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>   {
>   	unsigned long pfn;
> -	struct page *page;
>   	LIST_HEAD(source);
> +	struct folio *folio;
>   	static DEFINE_RATELIMIT_STATE(migrate_rs, DEFAULT_RATELIMIT_INTERVAL,
>   				      DEFAULT_RATELIMIT_BURST);
>   
>   	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
> -		struct folio *folio;
> -		bool isolated;
> +		struct page *page;
> +		bool huge;

Please use "hugetlb" if you mean hugetlb :)

>   
>   		if (!pfn_valid(pfn))
>   			continue;
> @@ -1812,34 +1812,22 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>   			continue;
>   		}
>   
> -		if (folio_test_hugetlb(folio)) {
> -			isolate_hugetlb(folio, &source);
> -			continue;
> +		huge = folio_test_hugetlb(folio);
> +		if (!huge) {
> +			folio = folio_get_nontail_page(page);
> +			if (!folio)
> +				continue;
>   		}

Hm, remind me why we are changing the hugetlb code to not take a 
reference here? It does look odd.
utback_movable_pages(&source);

-- 
Cheers,

David / dhildenb