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SubjectRe: [PATCH 4/7] migrate_pages(): fix failure counting for THP subpages retrying
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On 6/24/2022 10:53 AM, Huang Ying wrote:
> If THP is failed to be migrated for -ENOSYS and -ENOMEM, the THP will
> be split into thp_split_pages, and after other pages are migrated,
> pages in thp_split_pages will be migrated with no_subpage_counting ==
> true, because its failure have been counted already. If some pages in
> thp_split_pages are retried during migration, we should not count
> their failure if no_subpage_counting == true too. This is done this
> patch to fix the failure counting for THP subpages retrying.

Good catch. Totally agree with you. It seems we can move the condition
into -EAGAIN case like other cases did?

diff --git a/mm/migrate.c b/mm/migrate.c
index 1ece23d80bc4..491c2d07402b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1463,7 +1463,7 @@ int migrate_pages(struct list_head *from,
new_page_t get_new_page,
case -EAGAIN:
if (is_thp)
thp_retry++;
- else
+ else if (!no_subpage_counting)
retry++;
break;

Anyway this patch looks good to me.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> --- > mm/migrate.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 542533e4e3cf..61dab3025a1d 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1477,7 +1477,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> }
> }
> }
> - nr_failed += retry;
> + if (!no_subpage_counting)
> + nr_failed += retry;
> nr_thp_failed += thp_retry;
> /*
> * Try to migrate subpages of fail-to-migrate THPs, no nr_failed

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