[PATCH -V2 4/7] migrate_pages(): fix failure counting for THP subpages retrying

From: Huang Ying
Date: Mon Jul 11 2022 - 04:50:46 EST

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.

Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
mm/migrate.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 38e2c789a9c3..4bceba143db0 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