Re: [PATCH 7/7] migrate_pages(): fix failure counting for retry

[Baolin Wang]

On 6/27/2022 10:25 AM, Huang Ying wrote:
> After 10 retries, we will give up and the remaining pages will be
> counted as failure in nr_failed and nr_thp_failed.  We should count
> the failure in nr_failed_pages too.  This is done in this patch.
>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
> Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Cc: Zi Yan <ziy@xxxxxxxxxx>
> Cc: Yang Shi <shy828301@xxxxxxxxx>
> ---
>   mm/migrate.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 70a0e1f34c03..e42bd409d3aa 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1344,6 +1344,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   	int thp_retry = 1;
>   	int nr_failed = 0;
>   	int nr_failed_pages = 0;
> +	int nr_retry_pages = 0;
>   	int nr_succeeded = 0;
>   	int nr_thp_succeeded = 0;
>   	int nr_thp_failed = 0;
> @@ -1364,6 +1365,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
>   		retry = 0;
>   		thp_retry = 0;
> +		nr_retry_pages = 0;
>   
>   		list_for_each_entry_safe(page, page2, from, lru) {
>   			/*
> @@ -1449,12 +1451,14 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   				nr_thp_failed += thp_retry;
>   				if (!no_subpage_counting)
>   					nr_failed += retry;
> +				nr_failed_pages += nr_retry_pages;

Can you move this a little forward to update 'nr_failed_pages' in one 
place, which seems more readable?
nr_failed_pages += nr_subpages + nr_retry_pages;

Otherwise,
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>

>   				goto out;
>   			case -EAGAIN:
>   				if (is_thp)
>   					thp_retry++;
>   				else
>   					retry++;
> +				nr_retry_pages += nr_subpages;
>   				break;
>   			case MIGRATEPAGE_SUCCESS:
>   				nr_succeeded += nr_subpages;
> @@ -1481,6 +1485,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   	if (!no_subpage_counting)
>   		nr_failed += retry;
>   	nr_thp_failed += thp_retry;
> +	nr_failed_pages += nr_retry_pages;
>   	/*
>   	 * Try to migrate subpages of fail-to-migrate THPs, no nr_failed
>   	 * counting in this round, since all subpages of a THP is counted