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* [PATCH] mm: trivial mark_page_accessed() cleanup
@ 2019-10-16 22:53 Fengguang Wu
  2019-10-22 11:53 ` Vlastimil Babka
  0 siblings, 1 reply; 2+ messages in thread
From: Fengguang Wu @ 2019-10-16 22:53 UTC (permalink / raw)
  To: Linux Memory Management List, Andrew Morton
  Cc: Dave Hansen, Wu Fengguang, Liu Jingqi, LKML

This avoids duplicated PageReferenced() calls.
No behavior change.

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
  mm/swap.c | 14 +++++++++-----
  1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 38a52b9..c55720c 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -373,9 +373,15 @@ void mark_page_accessed(struct page *page)
  	page = compound_head(page);
  	inc_node_page_state(page, NR_ACCESSED);
  
-	if (!PageActive(page) && !PageUnevictable(page) &&
-			PageReferenced(page)) {
-
+	if (!PageReferenced(page)) {
+		SetPageReferenced(page);
+	} else if (PageUnevictable(page)) {
+		/*
+		 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
+		 * this list is never rotated or maintained, so marking an
+		 * evictable page accessed has no effect.
+		 */
+	} else if (!PageActive(page)) {
  		/*
  		 * If the page is on the LRU, queue it for activation via
  		 * activate_page_pvecs. Otherwise, assume the page is on a
@@ -389,8 +395,6 @@ void mark_page_accessed(struct page *page)
  		ClearPageReferenced(page);
  		if (page_is_file_cache(page))
  			workingset_activation(page);
-	} else if (!PageReferenced(page)) {
-		SetPageReferenced(page);
  	}
  	if (page_is_idle(page))
  		clear_page_idle(page);
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] mm: trivial mark_page_accessed() cleanup
  2019-10-16 22:53 [PATCH] mm: trivial mark_page_accessed() cleanup Fengguang Wu
@ 2019-10-22 11:53 ` Vlastimil Babka
  0 siblings, 0 replies; 2+ messages in thread
From: Vlastimil Babka @ 2019-10-22 11:53 UTC (permalink / raw)
  To: Fengguang Wu, Linux Memory Management List, Andrew Morton
  Cc: Dave Hansen, Liu Jingqi, LKML

On 10/17/19 12:53 AM, Fengguang Wu wrote:
> This avoids duplicated PageReferenced() calls.
> No behavior change.
> 
> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>   mm/swap.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/swap.c b/mm/swap.c
> index 38a52b9..c55720c 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -373,9 +373,15 @@ void mark_page_accessed(struct page *page)
>   	page = compound_head(page);
>   	inc_node_page_state(page, NR_ACCESSED);
>   
> -	if (!PageActive(page) && !PageUnevictable(page) &&
> -			PageReferenced(page)) {
> -
> +	if (!PageReferenced(page)) {
> +		SetPageReferenced(page);
> +	} else if (PageUnevictable(page)) {
> +		/*
> +		 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
> +		 * this list is never rotated or maintained, so marking an
> +		 * evictable page accessed has no effect.
> +		 */
> +	} else if (!PageActive(page)) {
>   		/*
>   		 * If the page is on the LRU, queue it for activation via
>   		 * activate_page_pvecs. Otherwise, assume the page is on a
> @@ -389,8 +395,6 @@ void mark_page_accessed(struct page *page)
>   		ClearPageReferenced(page);
>   		if (page_is_file_cache(page))
>   			workingset_activation(page);
> -	} else if (!PageReferenced(page)) {
> -		SetPageReferenced(page);
>   	}
>   	if (page_is_idle(page))
>   		clear_page_idle(page);
> 


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