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Date:   Wed, 25 May 2022 10:33:58 +0200
From:   Oscar Salvador <osalvador@suse.de>
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     akpm@linux-foundation.org, mike.kravetz@oracle.com,
        naoya.horiguchi@nec.com, peterx@redhat.com, apopple@nvidia.com,
        ying.huang@intel.com, david@redhat.com, songmuchun@bytedance.com,
        hch@lst.de, dhowells@redhat.com, cl@linux.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/4] mm/migration: remove unneeded lock page and
 PageMovable check
Message-ID: <Yo3p9qhDWmcoJXV6@localhost.localdomain>
References: <20220525081822.53547-1-linmiaohe@huawei.com>
 <20220525081822.53547-3-linmiaohe@huawei.com>
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On Wed, May 25, 2022 at 04:18:20PM +0800, 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@huawei.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Oscar Salvador <osalvador@suse.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;
>  	}
>  
> -- 
> 2.23.0
> 
> 

-- 
Oscar Salvador
SUSE Labs