migrate_pages(): remove unnecessary list_safe_reset_next()

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.

Link: https://lkml.kernel.org/r/20220817081408.513338-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 1758fd215c0a77353d49f342be2026108663bb8d..19a9b26af7e2c71d0a1f568b2eb3d8bb0423d817 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1369,16 +1369,13 @@ out:
        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;
 }
@@ -1482,7 +1479,7 @@ retry:
                                /* 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;
                                        }
@@ -1501,7 +1498,7 @@ retry:
                                 */
                                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;
                                        }