linux-kernel - Re: [PATCH 4/8] mm/migrate.c: wrap do_move_pages_to_node() and store

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Date:   Mon, 20 Jan 2020 10:49:49 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Wei Yang <richardw.yang@...ux.intel.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, yang.shi@...ux.alibaba.com
Subject: Re: [PATCH 4/8] mm/migrate.c: wrap do_move_pages_to_node() and
 store_status()

On Sun 19-01-20 11:06:32, Wei Yang wrote:
> Usually do_move_pages_to_node() and store_status() is a pair. There are
> three places call this pair of functions with almost the same form.
> 
> This patch just wrap it to make it friendly to audience and also
> consolidate the move and store action into one place. Also mentioned by
> Yang Shi, the handling of do_move_pages_to_node()'s return value is not
> proper. Now we can fix it in one place.

The helper helps here indeed. Thanks this makes the code easier to read.
> 
> Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>

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

> ---
>  mm/migrate.c | 34 +++++++++++++++++++---------------
>  1 file changed, 19 insertions(+), 15 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 4a63fb8fbb6d..dec147d3a4dd 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1583,6 +1583,19 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
>  	return err;
>  }
>  
> +static int move_pages_and_store_status(struct mm_struct *mm, int node,
> +		struct list_head *pagelist, int __user *status,
> +		int start, int nr)
> +{
> +	int err;
> +
> +	err = do_move_pages_to_node(mm, pagelist, node);
> +	if (err)
> +		return err;
> +	err = store_status(status, start, node, nr);
> +	return err;
> +}
> +
>  /*
>   * Migrate an array of page address onto an array of nodes and fill
>   * the corresponding array of status.
> @@ -1629,10 +1642,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  			current_node = node;
>  			start = i;
>  		} else if (node != current_node) {
> -			err = do_move_pages_to_node(mm, &pagelist, current_node);
> -			if (err)
> -				goto out;
> -			err = store_status(status, start, current_node, i - start);
> +			err = move_pages_and_store_status(mm, current_node,
> +					&pagelist, status, start, i - start);
>  			if (err)
>  				goto out;
>  			start = i;
> @@ -1661,10 +1672,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  		if (err)
>  			goto out_flush;
>  
> -		err = do_move_pages_to_node(mm, &pagelist, current_node);
> -		if (err)
> -			goto out;
> -		err = store_status(status, start, current_node, i - start);
> +		err = move_pages_and_store_status(mm, current_node, &pagelist,
> +				status, start, i - start);
>  		if (err)
>  			goto out;
>  		current_node = NUMA_NO_NODE;
> @@ -1674,13 +1683,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  		return err;
>  
>  	/* Make sure we do not overwrite the existing error */
> -	err1 = do_move_pages_to_node(mm, &pagelist, current_node);
> -	if (err1) {
> -		if (err >= 0)
> -			err = err1;
> -		goto out;
> -	}
> -	err1 = store_status(status, start, current_node, i - start);
> +	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
> +				status, start, i - start);
>  	if (err >= 0)
>  		err = err1;
>  out:
> -- 
> 2.17.1
> 

-- 
Michal Hocko
SUSE Labs