2022-05-25 14:08:22

by Miaohe Lin

Subject: [PATCH v3 2/4] mm/migration: remove unneeded lock page and PageMovable check

When non-lru movable page was freed from under us, __ClearPageMovable must
have been done. So we can remove unneeded lock page and PageMovable check
here. Also free_pages_prepare() will clear PG_isolated for us, so we can
further remove ClearPageIsolated as suggested by David.

Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
---
mm/migrate.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index e88ebb88fa6f..337336115e43 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1090,15 +1090,10 @@ static int unmap_and_move(new_page_t get_new_page,
return -ENOSYS;

if (page_count(page) == 1) {
- /* page was freed from under us. So we are done. */
+ /* Page was freed from under us. So we are done. */
ClearPageActive(page);
ClearPageUnevictable(page);
- if (unlikely(__PageMovable(page))) {
- lock_page(page);
- if (!PageMovable(page))
- ClearPageIsolated(page);
- unlock_page(page);
- }
+ /* free_pages_prepare() will clear PG_isolated. */
goto out;
}

--
2.23.0

2022-05-26 02:15:54

by Oscar Salvador

Subject: Re: [PATCH v3 2/4] mm/migration: remove unneeded lock page and PageMovable check

On Wed, May 25, 2022 at 04:18:20PM +0800, Miaohe Lin wrote:
> When non-lru movable page was freed from under us, __ClearPageMovable must
> have been done. So we can remove unneeded lock page and PageMovable check
> here. Also free_pages_prepare() will clear PG_isolated for us, so we can
> further remove ClearPageIsolated as suggested by David.
>
> Signed-off-by: Miaohe Lin <[email protected]>
> Reviewed-by: Christoph Hellwig <[email protected]>

Reviewed-by: Oscar Salvador <[email protected]>

> ---
> mm/migrate.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index e88ebb88fa6f..337336115e43 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1090,15 +1090,10 @@ static int unmap_and_move(new_page_t get_new_page,
> return -ENOSYS;
>
> if (page_count(page) == 1) {
> - /* page was freed from under us. So we are done. */
> + /* Page was freed from under us. So we are done. */
> ClearPageActive(page);
> ClearPageUnevictable(page);
> - if (unlikely(__PageMovable(page))) {
> - lock_page(page);
> - if (!PageMovable(page))
> - ClearPageIsolated(page);
> - unlock_page(page);
> - }
> + /* free_pages_prepare() will clear PG_isolated. */
> goto out;
> }
>
> --
> 2.23.0
>
>

--
Oscar Salvador
SUSE Labs