[PATCH -V2 2/7] migrate_pages(): remove unnecessary list_safe_reset_next()

Huang Ying
2022-07-11T08:50:10Z

Before commit b5bade978e9b ("mm: migrate: fix the return value of
migrate_pages()"), the tail pages of THP will be put in the "from"
list directly. So one of the loop cursors (page2) needs to be reset,
as is done in try_split_thp() via list_safe_reset_next(). But after
the commit, the tail pages of THP will be put in a dedicated
list (thp_split_pages). That is, the "from" list will not be changed
during splitting. So, it's unnecessary to call list_safe_reset_next()
anymore.

This is a code cleanup, no functionality changes are expected.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
---
mm/migrate.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 472335f0aaa3..794312072eb3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1301,16 +1301,13 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
return rc;
}

-static inline int try_split_thp(struct page *page, struct page **page2,
- struct list_head *from)
+static inline int try_split_thp(struct page *page, struct list_head *split_pages)
{
- int rc = 0;
+ int rc;

lock_page(page);
- rc = split_huge_page_to_list(page, from);
+ rc = split_huge_page_to_list(page, split_pages);
unlock_page(page);
- if (!rc)
- list_safe_reset_next(page, *page2, lru);

return rc;
}
@@ -1414,7 +1411,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
/* THP migration is unsupported */
if (is_thp) {
nr_thp_failed++;
- if (!try_split_thp(page, &page2, &thp_split_pages)) {
+ if (!try_split_thp(page, &thp_split_pages)) {
nr_thp_split++;
goto retry;
}
@@ -1433,7 +1430,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
*/
if (is_thp && !nosplit) {
nr_thp_failed++;
- if (!try_split_thp(page, &page2, &thp_split_pages)) {
+ if (!try_split_thp(page, &thp_split_pages)) {
nr_thp_split++;
goto retry;
}
--
2.30.2