Re: [PATCH 4/8] mm/migrate.c: wrap do_move_pages_to_node() and store_status()

Michal Hocko
2020-01-20T09:49:54Z

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@linux.intel.com>

Acked-by: Michal Hocko <mhocko@suse.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