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Date:   Mon, 20 Jan 2020 10:52:16 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Wei Yang <richardw.yang@linux.intel.com>
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, yang.shi@linux.alibaba.com
Subject: Re: [PATCH 5/8] mm/migrate.c: check pagelist in
 move_pages_and_store_status()
Message-ID: <20200120095216.GP18451@dhcp22.suse.cz>
References: <20200119030636.11899-1-richardw.yang@linux.intel.com>
 <20200119030636.11899-6-richardw.yang@linux.intel.com>
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On Sun 19-01-20 11:06:33, Wei Yang wrote:
> When pagelist is empty, it is not necessary to do the move and store.
> Also it consolidate the empty list check in one place.

OK looks good to me.
 
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/migrate.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index dec147d3a4dd..46a5697b7fc6 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm,
>  {
>  	int err;
>  
> -	if (list_empty(pagelist))
> -		return 0;
> -
>  	err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
>  			MIGRATE_SYNC, MR_SYSCALL);
>  	if (err)
> @@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node,
>  {
>  	int err;
>  
> +	if (list_empty(pagelist))
> +		return 0;
> +
>  	err = do_move_pages_to_node(mm, pagelist, node);
>  	if (err)
>  		return err;
> @@ -1679,9 +1679,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  		current_node = NUMA_NO_NODE;
>  	}
>  out_flush:
> -	if (list_empty(&pagelist))
> -		return err;
> -
>  	/* Make sure we do not overwrite the existing error */
>  	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
>  				status, start, i - start);
> -- 
> 2.17.1
> 

-- 
Michal Hocko
SUSE Labs