Re: [PATCH] mm/gup: Add folio to list when folio_isolate_lru() succeed

[Andrew Morton]

On Tue, 31 Jan 2023 14:32:06 +0800 Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx> wrote:

> If we call folio_isolate_lru() successfully, we will get
> return value 0. We need to add this folio to the
> movable_pages_list.
> 
> Fixes: 67e139b02d99 ("mm/gup.c: refactor check_and_migrate_movable_pages()")
> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx>
>
> ...
>
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1914,7 +1914,7 @@ static unsigned long collect_longterm_unpinnable_pages(
>  			drain_allow = false;
>  		}
>  
> -		if (!folio_isolate_lru(folio))
> +		if (folio_isolate_lru(folio))
>  			continue;
>  
>  		list_add_tail(&folio->lru, movable_page_list);

Thanks.  What are the user-visible effects of this bug?