Replace migrate_page_add() with migrate_folio_add().  migrate_folio_add()
does the same a migrate_page_add() but takes in a folio instead of a page.
This removes a couple of calls to compound_head().

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 mm/mempolicy.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 6a68dbce3b70..0919c7a719d4 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -414,7 +414,7 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
 	},
 };
 
-static int migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
 				unsigned long flags);
 
 struct queue_pages {
@@ -476,7 +476,7 @@ static int queue_folios_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
 	/* go to folio migration */
 	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
 		if (!vma_migratable(walk->vma) ||
-		    migrate_page_add(&folio->page, qp->pagelist, flags)) {
+		    migrate_folio_add(folio, qp->pagelist, flags)) {
 			ret = 1;
 			goto unlock;
 		}
@@ -544,7 +544,7 @@ static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
 			 * temporary off LRU pages in the range.  Still
 			 * need migrate other LRU pages.
 			 */
-			if (migrate_page_add(&folio->page, qp->pagelist, flags))
+			if (migrate_folio_add(folio, qp->pagelist, flags))
 				has_unmovable = true;
 		} else
 			break;
@@ -1021,27 +1021,28 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
 }
 
 #ifdef CONFIG_MIGRATION
-/*
- * page migration, thp tail pages can be passed.
- */
-static int migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
 				unsigned long flags)
 {
-	struct page *head = compound_head(page);
 	/*
-	 * Avoid migrating a page that is shared with others.
+	 * We try to migrate only unshared folios. If it is shared it
+	 * is likely not worth migrating.
+	 *
+	 * To check if the folio is shared, ideally we want to make sure
+	 * every page is mapped to the same process. Doing that is very
+	 * expensive, so check the estimated mapcount of the folio instead.
 	 */
-	if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(head) == 1) {
-		if (!isolate_lru_page(head)) {
-			list_add_tail(&head->lru, pagelist);
-			mod_node_page_state(page_pgdat(head),
-				NR_ISOLATED_ANON + page_is_file_lru(head),
-				thp_nr_pages(head));
+	if ((flags & MPOL_MF_MOVE_ALL) || folio_estimated_sharers(folio) == 1) {
+		if (!folio_isolate_lru(folio)) {
+			list_add_tail(&folio->lru, foliolist);
+			node_stat_mod_folio(folio,
+				NR_ISOLATED_ANON + folio_is_file_lru(folio),
+				folio_nr_pages(folio));
 		} else if (flags & MPOL_MF_STRICT) {
 			/*
-			 * Non-movable page may reach here.  And, there may be
-			 * temporary off LRU pages or non-LRU movable pages.
-			 * Treat them as unmovable pages since they can't be
+			 * Non-movable folio may reach here.  And, there may be
+			 * temporary off LRU folios or non-LRU movable folios.
+			 * Treat them as unmovable folios since they can't be
 			 * isolated, so they can't be moved at the moment.  It
 			 * should return -EIO for this case too.
 			 */
@@ -1235,7 +1236,7 @@ static struct page *new_page(struct page *page, unsigned long start)
 }
 #else
 
-static int migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
 				unsigned long flags)
 {
 	return -EIO;
-- 
2.38.1

On 1/31/2023 4:18 AM, Vishal Moola (Oracle) wrote:
> Replace migrate_page_add() with migrate_folio_add().  migrate_folio_add()
> does the same a migrate_page_add() but takes in a folio instead of a page.
> This removes a couple of calls to compound_head().
> 
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>

Regards
Yin, Fengwei

> ---
>  mm/mempolicy.c | 39 ++++++++++++++++++++-------------------
>  1 file changed, 20 insertions(+), 19 deletions(-)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 6a68dbce3b70..0919c7a719d4 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -414,7 +414,7 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
>  	},
>  };
>  
> -static int migrate_page_add(struct page *page, struct list_head *pagelist,
> +static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
>  				unsigned long flags);
>  
>  struct queue_pages {
> @@ -476,7 +476,7 @@ static int queue_folios_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
>  	/* go to folio migration */
>  	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
>  		if (!vma_migratable(walk->vma) ||
> -		    migrate_page_add(&folio->page, qp->pagelist, flags)) {
> +		    migrate_folio_add(folio, qp->pagelist, flags)) {
>  			ret = 1;
>  			goto unlock;
>  		}
> @@ -544,7 +544,7 @@ static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
>  			 * temporary off LRU pages in the range.  Still
>  			 * need migrate other LRU pages.
>  			 */
> -			if (migrate_page_add(&folio->page, qp->pagelist, flags))
> +			if (migrate_folio_add(folio, qp->pagelist, flags))
>  				has_unmovable = true;
>  		} else
>  			break;
> @@ -1021,27 +1021,28 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
>  }
>  
>  #ifdef CONFIG_MIGRATION
> -/*
> - * page migration, thp tail pages can be passed.
> - */
> -static int migrate_page_add(struct page *page, struct list_head *pagelist,
> +static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
>  				unsigned long flags)
>  {
> -	struct page *head = compound_head(page);
>  	/*
> -	 * Avoid migrating a page that is shared with others.
> +	 * We try to migrate only unshared folios. If it is shared it
> +	 * is likely not worth migrating.
> +	 *
> +	 * To check if the folio is shared, ideally we want to make sure
> +	 * every page is mapped to the same process. Doing that is very
> +	 * expensive, so check the estimated mapcount of the folio instead.
>  	 */
> -	if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(head) == 1) {
> -		if (!isolate_lru_page(head)) {
> -			list_add_tail(&head->lru, pagelist);
> -			mod_node_page_state(page_pgdat(head),
> -				NR_ISOLATED_ANON + page_is_file_lru(head),
> -				thp_nr_pages(head));
> +	if ((flags & MPOL_MF_MOVE_ALL) || folio_estimated_sharers(folio) == 1) {
> +		if (!folio_isolate_lru(folio)) {
> +			list_add_tail(&folio->lru, foliolist);
> +			node_stat_mod_folio(folio,
> +				NR_ISOLATED_ANON + folio_is_file_lru(folio),
> +				folio_nr_pages(folio));
>  		} else if (flags & MPOL_MF_STRICT) {
>  			/*
> -			 * Non-movable page may reach here.  And, there may be
> -			 * temporary off LRU pages or non-LRU movable pages.
> -			 * Treat them as unmovable pages since they can't be
> +			 * Non-movable folio may reach here.  And, there may be
> +			 * temporary off LRU folios or non-LRU movable folios.
> +			 * Treat them as unmovable folios since they can't be
>  			 * isolated, so they can't be moved at the moment.  It
>  			 * should return -EIO for this case too.
>  			 */
> @@ -1235,7 +1236,7 @@ static struct page *new_page(struct page *page, unsigned long start)
>  }
>  #else
>  
> -static int migrate_page_add(struct page *page, struct list_head *pagelist,
> +static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
>  				unsigned long flags)
>  {
>  	return -EIO;