diff mbox series

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

Message ID 20220624025309.1033400-3-ying.huang@intel.com (mailing list archive)
State New
Headers show
Series [1/7] migrate: fix syscall move_pages() return value for failure | expand

Commit Message

Huang, Ying June 24, 2022, 2:53 a.m. UTC
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>
Cc: 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(-)

Comments

Baolin Wang June 24, 2022, 9:22 a.m. UTC | #1
On 6/24/2022 10:53 AM, Huang Ying wrote:
> 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>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> ---

Looks good to me.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>


>   mm/migrate.c | 13 +++++--------
>   1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index a271554be7a1..82444e7df9f1 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1300,16 +1300,13 @@ 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;
>   }
> @@ -1413,7 +1410,7 @@ 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;
>   					}
> @@ -1432,7 +1429,7 @@ 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;
>   					}
diff mbox series

Patch

diff --git a/mm/migrate.c b/mm/migrate.c
index a271554be7a1..82444e7df9f1 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1300,16 +1300,13 @@  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;
 }
@@ -1413,7 +1410,7 @@  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;
 					}
@@ -1432,7 +1429,7 @@  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;
 					}