linux-kernel - Re: [PATCH v4 2/4] mm/migration: remove unneeded lock page and PageMovable check

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Date:   Tue, 31 May 2022 14:50:53 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Miaohe Lin <linmiaohe@...wei.com>, akpm@...ux-foundation.org,
        naoya.horiguchi@....com
Cc:     peterx@...hat.com, apopple@...dia.com, ying.huang@...el.com,
        osalvador@...e.de, mike.kravetz@...cle.com,
        songmuchun@...edance.com, hch@....de, dhowells@...hat.com,
        cl@...ux.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/4] mm/migration: remove unneeded lock page and
 PageMovable check

On 30.05.22 13:30, Miaohe Lin wrote:
> When non-lru movable page was freed from under us, __ClearPageMovable must
> have been done.  So we can remove unneeded lock page and PageMovable check
> here. Also free_pages_prepare() will clear PG_isolated for us, so we can
> further remove ClearPageIsolated as suggested by David.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> Reviewed-by: Christoph Hellwig <hch@....de>
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> ---
>  mm/migrate.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index e88ebb88fa6f..337336115e43 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1090,15 +1090,10 @@ static int unmap_and_move(new_page_t get_new_page,
>  		return -ENOSYS;
>  
>  	if (page_count(page) == 1) {
> -		/* page was freed from under us. So we are done. */
> +		/* Page was freed from under us. So we are done. */
>  		ClearPageActive(page);
>  		ClearPageUnevictable(page);
> -		if (unlikely(__PageMovable(page))) {
> -			lock_page(page);
> -			if (!PageMovable(page))
> -				ClearPageIsolated(page);
> -			unlock_page(page);
> -		}
> +		/* free_pages_prepare() will clear PG_isolated. */
>  		goto out;
>  	}
>  

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb