Re: [PATCH v3 5/5] mm: memory_hotplug: unify Huge/LRU/non-LRU movable folio isolation

[Miaohe Lin <linmiaohe@huawei.com>]

On 2024/8/27 19:47, 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 1335fb6ef7fa..5f09866d17cf 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1772,15 +1772,15 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
>  
>  static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>  {
> +	struct folio *folio;
>  	unsigned long pfn;
> -	struct page *page;
>  	LIST_HEAD(source);
>  	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 hugetlb;
>  
>  		if (!pfn_valid(pfn))
>  			continue;
> @@ -1811,34 +1811,22 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
>  			continue;
>  		}
>  
> -		if (folio_test_hugetlb(folio)) {
> -			isolate_hugetlb(folio, &source);
> -			continue;
> +		hugetlb = folio_test_hugetlb(folio);
> +		if (!hugetlb) {
> +			folio = folio_get_nontail_page(page);
> +			if (!folio)
> +				continue;
>  		}
>  
> -		if (!get_page_unless_zero(page))
> -			continue;
> -		/*
> -		 * We can skip free pages. And we can deal with pages on
> -		 * LRU and non-lru movable pages.
> -		 */
> -		if (PageLRU(page))
> -			isolated = isolate_lru_page(page);
> -		else
> -			isolated = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
> -		if (isolated) {
> -			list_add_tail(&page->lru, &source);

This has a side effect that list_add_tail is replaced with list_add now. But it seems this
won't cause any problem.

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Thanks.
.