linux-kernel - Re: [Patch v3 2/4] mm/migrate.c: wrap do_move_pages_to_node() and store

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Date:   Mon, 27 Jan 2020 10:36:42 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Wei Yang <richardw.yang@...ux.intel.com>
Cc:     akpm@...ux-foundation.org, yang.shi@...ux.alibaba.com,
        rientjes@...gle.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Patch v3 2/4] mm/migrate.c: wrap do_move_pages_to_node() and
 store_status()

On Sun 26-01-20 18:26:21, 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.
> 
> Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>

I believe I have already acked this one. Anyway
Acked-by: Michal Hocko <mhocko@...e.com>

> ---
>  mm/migrate.c | 61 ++++++++++++++++++++++++++--------------------------
>  1 file changed, 30 insertions(+), 31 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index ae3db45c6a42..e816c8990296 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1583,6 +1583,29 @@ 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,
> +		unsigned long nr_pages, int start, int i)
> +{
> +	int err;
> +
> +	err = do_move_pages_to_node(mm, pagelist, node);
> +	if (err) {
> +		/*
> +		 * Positive err means the number of failed
> +		 * pages to migrate.  Since we are going to
> +		 * abort and return the number of non-migrated
> +		 * pages, so need incude the rest of the
> +		 * nr_pages that have not attempted as well.
> +		 */
> +		if (err > 0)
> +			err += nr_pages - i - 1;
> +		return err;
> +	}
> +	err = store_status(status, start, node, i - start);
> +	return err;
> +}
> +
>  /*
>   * Migrate an array of page address onto an array of nodes and fill
>   * the corresponding array of status.
> @@ -1626,20 +1649,9 @@ 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) {
> -				/*
> -				 * Positive err means the number of failed
> -				 * pages to migrate.  Since we are going to
> -				 * abort and return the number of non-migrated
> -				 * pages, so need incude the rest of the
> -				 * nr_pages that have not attempted as well.
> -				 */
> -				if (err > 0)
> -					err += nr_pages - i - 1;
> -				goto out;
> -			}
> -			err = store_status(status, start, current_node, i - start);
> +			err = move_pages_and_store_status(mm, current_node,
> +					&pagelist, status, nr_pages,
> +					start, i);
>  			if (err)
>  				goto out;
>  			start = i;
> @@ -1668,13 +1680,8 @@ 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) {
> -			if (err > 0)
> -				err += nr_pages - i - 1;
> -			goto out;
> -		}
> -		err = store_status(status, start, current_node, i - start);
> +		err = move_pages_and_store_status(mm, current_node, &pagelist,
> +				status, nr_pages, start, i);
>  		if (err)
>  			goto out;
>  		current_node = NUMA_NO_NODE;
> @@ -1684,16 +1691,8 @@ 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);
> -	/*
> -	 * Don't have to report non-attempted pages here since:
> -	 *     - If the above loop is done gracefully there is not non-attempted
> -	 *       page.
> -	 *     - If the above loop is aborted to it means more fatal error
> -	 *       happened, should return err.
> -	 */
> -	if (!err1)
> -		err1 = store_status(status, start, current_node, i - start);
> +	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
> +			status, nr_pages, start, i);
>  	if (err >= 0)
>  		err = err1;
>  out:
> -- 
> 2.17.1

-- 
Michal Hocko
SUSE Labs