[PATCH] mm/compaction: remove local variable is_lru

[PATCH] mm/compaction: remove local variable is_lru

[Ganesh Mahendran]

local varialbe is_lru was used for tracking non-lru pages(such as
balloon pages).

But commit
112ea7b668d3 ("mm: migrate: support non-lru movable page migration")
introduced a common framework for non-lru page migration and moved
the compound pages check before non-lru movable pages check.

So there is no need to use local variable is_lru.

Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
---
 mm/compaction.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index fbb7b38..780be7f 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -724,7 +724,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 	/* Time to isolate some pages for migration */
 	for (; low_pfn < end_pfn; low_pfn++) {
-		bool is_lru;
 
 		if (skip_on_failure && low_pfn >= next_skip_pfn) {
 			/*
@@ -807,8 +806,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 		 * It's possible to migrate LRU and non-lru movable pages.
 		 * Skip any other type of page
 		 */
-		is_lru = PageLRU(page);
-		if (!is_lru) {
+		if (!PageLRU(page)) {
 			/*
 			 * __PageMovable can return false positive so we need
 			 * to verify it under page_lock.
-- 
1.9.1

Re: [PATCH] mm/compaction: remove local variable is_lru

[Hillf Danton]

> 
> local varialbe is_lru was used for tracking non-lru pages(such as
> balloon pages).
> 
> But commit
> 112ea7b668d3 ("mm: migrate: support non-lru movable page migration")
> introduced a common framework for non-lru page migration and moved
> the compound pages check before non-lru movable pages check.
> 
> So there is no need to use local variable is_lru.
> 
> Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
> ---

Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

>  mm/compaction.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index fbb7b38..780be7f 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -724,7 +724,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> 
>  	/* Time to isolate some pages for migration */
>  	for (; low_pfn < end_pfn; low_pfn++) {
> -		bool is_lru;
> 
>  		if (skip_on_failure && low_pfn >= next_skip_pfn) {
>  			/*
> @@ -807,8 +806,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>  		 * It's possible to migrate LRU and non-lru movable pages.
>  		 * Skip any other type of page
>  		 */
> -		is_lru = PageLRU(page);
> -		if (!is_lru) {
> +		if (!PageLRU(page)) {
>  			/*
>  			 * __PageMovable can return false positive so we need
>  			 * to verify it under page_lock.
> --
> 1.9.1

Re: [PATCH] mm/compaction: remove local variable is_lru

[Michal Hocko]

On Fri 17-06-16 17:32:51, Ganesh Mahendran wrote:
> local varialbe is_lru was used for tracking non-lru pages(such as
> balloon pages).
> 
> But commit
> 112ea7b668d3 ("mm: migrate: support non-lru movable page migration")

this commit sha is not stable because it is from the linux-next tree.

> introduced a common framework for non-lru page migration and moved
> the compound pages check before non-lru movable pages check.
> 
> So there is no need to use local variable is_lru.
> 
> Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>

Other than that the patch looks ok and maybe it would be worth folding
into the mm-migrate-support-non-lru-movable-page-migration.patch

> ---
>  mm/compaction.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index fbb7b38..780be7f 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -724,7 +724,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>  
>  	/* Time to isolate some pages for migration */
>  	for (; low_pfn < end_pfn; low_pfn++) {
> -		bool is_lru;
>  
>  		if (skip_on_failure && low_pfn >= next_skip_pfn) {
>  			/*
> @@ -807,8 +806,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>  		 * It's possible to migrate LRU and non-lru movable pages.
>  		 * Skip any other type of page
>  		 */
> -		is_lru = PageLRU(page);
> -		if (!is_lru) {
> +		if (!PageLRU(page)) {
>  			/*
>  			 * __PageMovable can return false positive so we need
>  			 * to verify it under page_lock.
> -- 
> 1.9.1
> 

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] mm/compaction: remove local variable is_lru

[Vlastimil Babka]

On 06/17/2016 11:50 AM, Michal Hocko wrote:
> On Fri 17-06-16 17:32:51, Ganesh Mahendran wrote:
>> local varialbe is_lru was used for tracking non-lru pages(such as
>> balloon pages).
>>
>> But commit
>> 112ea7b668d3 ("mm: migrate: support non-lru movable page migration")
>
> this commit sha is not stable because it is from the linux-next tree.
>
>> introduced a common framework for non-lru page migration and moved
>> the compound pages check before non-lru movable pages check.
>>
>> So there is no need to use local variable is_lru.
>>
>> Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
>
> Other than that the patch looks ok and maybe it would be worth folding
> into the mm-migrate-support-non-lru-movable-page-migration.patch

Agreed.