Commit 9c62ff00 authored by Huang Ying's avatar Huang Ying Committed by Andrew Morton
Browse files

migrate_pages(): remove unnecessary list_safe_reset_next() 

Before commit b5bade97 ("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: default avatar"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a7504ed1

mm/migrate.c

+5 −8
Original line number Diff line number Diff line
@@ -1369,16 +1369,13 @@ 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;

}
@@ -1482,7 +1479,7 @@ 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;

					}
@@ -1501,7 +1498,7 @@ 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;

					}