* [PATCH] mm:remove useless code
@ 2020-12-23 7:13 hui yang
2020-12-23 7:32 ` Hao Lee
2020-12-23 7:43 ` Souptick Joarder
0 siblings, 2 replies; 3+ messages in thread
From: hui yang @ 2020-12-23 7:13 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, YangHui
From: YangHui <yanghui.def@gmail.com>
remove useless code
Signed-off-by: YangHui <yanghui.def@gmail.com>
---
mm/vmscan.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 257cba7..af1d176 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1234,8 +1234,8 @@ static unsigned int shrink_page_list(struct list_head *page_list,
* Try to allocate it some swap space here.
* Lazyfree page could be freed directly
*/
- if (PageAnon(page) && PageSwapBacked(page)) {
- if (!PageSwapCache(page)) {
+ if (PageAnon(page) && PageSwapBacked(page) &&
+ !PageSwapCache(page)) {
if (!(sc->gfp_mask & __GFP_IO))
goto keep_locked;
if (PageTransHuge(page)) {
@@ -1270,7 +1270,6 @@ static unsigned int shrink_page_list(struct list_head *page_list,
/* Adding to swap updated mapping */
mapping = page_mapping(page);
- }
} else if (unlikely(PageTransHuge(page))) {
/* Split file THP */
if (split_huge_page_to_list(page, page_list))
--
2.7.4
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm:remove useless code
2020-12-23 7:13 [PATCH] mm:remove useless code hui yang
@ 2020-12-23 7:32 ` Hao Lee
2020-12-23 7:43 ` Souptick Joarder
1 sibling, 0 replies; 3+ messages in thread
From: Hao Lee @ 2020-12-23 7:32 UTC (permalink / raw)
To: hui yang; +Cc: akpm, linux-mm
On Wed, Dec 23, 2020 at 3:13 PM hui yang <yanghui.def@gmail.com> wrote:
>
> From: YangHui <yanghui.def@gmail.com>
>
> remove useless code
>
> Signed-off-by: YangHui <yanghui.def@gmail.com>
> ---
> mm/vmscan.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 257cba7..af1d176 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1234,8 +1234,8 @@ static unsigned int shrink_page_list(struct list_head *page_list,
> * Try to allocate it some swap space here.
> * Lazyfree page could be freed directly
> */
> - if (PageAnon(page) && PageSwapBacked(page)) {
> - if (!PageSwapCache(page)) {
> + if (PageAnon(page) && PageSwapBacked(page) &&
> + !PageSwapCache(page)) {
I think this is incorrect.
Consider this scenario:
PageAnon(page) && PageSwapBacked(page) is true
!PageSwapCache(page) is false
In original logic, this snippet will run into the first if branch which
does nothing actually. However, in your logic, this snippet will run
into else if branch.
Regards,
Hao Lee
> if (!(sc->gfp_mask & __GFP_IO))
> goto keep_locked;
> if (PageTransHuge(page)) {
> @@ -1270,7 +1270,6 @@ static unsigned int shrink_page_list(struct list_head *page_list,
>
> /* Adding to swap updated mapping */
> mapping = page_mapping(page);
> - }
> } else if (unlikely(PageTransHuge(page))) {
> /* Split file THP */
> if (split_huge_page_to_list(page, page_list))
> --
> 2.7.4
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm:remove useless code
2020-12-23 7:13 [PATCH] mm:remove useless code hui yang
2020-12-23 7:32 ` Hao Lee
@ 2020-12-23 7:43 ` Souptick Joarder
1 sibling, 0 replies; 3+ messages in thread
From: Souptick Joarder @ 2020-12-23 7:43 UTC (permalink / raw)
To: hui yang; +Cc: Andrew Morton, Linux-MM
On Wed, Dec 23, 2020 at 12:43 PM hui yang <yanghui.def@gmail.com> wrote:
>
> From: YangHui <yanghui.def@gmail.com>
>
> remove useless code
Change logs need to be more descriptive.
>
> Signed-off-by: YangHui <yanghui.def@gmail.com>
> ---
> mm/vmscan.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 257cba7..af1d176 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1234,8 +1234,8 @@ static unsigned int shrink_page_list(struct list_head *page_list,
> * Try to allocate it some swap space here.
> * Lazyfree page could be freed directly
> */
> - if (PageAnon(page) && PageSwapBacked(page)) {
> - if (!PageSwapCache(page)) {
> + if (PageAnon(page) && PageSwapBacked(page) &&
> + !PageSwapCache(page)) {
This will change the original behaviour of the code.
> if (!(sc->gfp_mask & __GFP_IO))
> goto keep_locked;
> if (PageTransHuge(page)) {
> @@ -1270,7 +1270,6 @@ static unsigned int shrink_page_list(struct list_head *page_list,
>
> /* Adding to swap updated mapping */
> mapping = page_mapping(page);
> - }
> } else if (unlikely(PageTransHuge(page))) {
> /* Split file THP */
> if (split_huge_page_to_list(page, page_list))
> --
> 2.7.4
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-12-23 7:13 [PATCH] mm:remove useless code hui yang
2020-12-23 7:32 ` Hao Lee
2020-12-23 7:43 ` Souptick Joarder
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