The patch titled
Subject: migrate_pages(): remove unnecessary list_safe_reset_next()
has been added to the -mm mm-unstable branch. Its filename is
migrate_pages-remove-unnecessary-list_safe_reset_next.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/migrate_pages-remove-unnecessary-list_safe_reset_next.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: migrate_pages(): remove unnecessary list_safe_reset_next()
Date: Wed, 17 Aug 2022 16:14:02 +0800
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@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
--- a/mm/migrate.c~migrate_pages-remove-unnecessary-list_safe_reset_next
+++ a/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;
}
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
memory-tiering-hot-page-selection-with-hint-page-fault-latency.patch
memory-tiering-rate-limit-numa-migration-throughput.patch
memory-tiering-adjust-hot-threshold-automatically.patch
migrate-fix-syscall-move_pages-return-value-for-failure.patch
migrate_pages-remove-unnecessary-list_safe_reset_next.patch
migrate_pages-fix-thp-failure-counting-for-enomem.patch
migrate_pages-fix-failure-counting-for-thp-subpages-retrying.patch
migrate_pages-fix-failure-counting-for-thp-on-enosys.patch
migrate_pages-fix-failure-counting-for-thp-splitting.patch
migrate_pages-fix-failure-counting-for-retry.patch
