[PATCH 0/2] migrate: convert migrate_pages()/unmap_and_move() to use folios

[PATCH 0/2] migrate: convert migrate_pages()/unmap_and_move() to use folios

[Huang Ying]

The conversion is quite straightforward, just replace the page API to
the corresponding folio API.  migrate_pages() and unmap_and_move()
mostly work with folios (head pages) only.

Changelog:

rfc -> v1:

- Change API to test transhuge and hugetlb, per Matthew and Zi's comments.

- Make THP related statistics for THP only, per Matthew's comments.

Best Regards,
Huang, Ying

[PATCH 1/2] migrate: convert unmap_and_move() to use folios

[Huang Ying]

Quite straightforward, the page functions are converted to
corresponding folio functions.  Same for comments.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
---
 mm/migrate.c | 54 ++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index dff333593a8a..f6dd749dd2f8 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1150,79 +1150,79 @@ static int __unmap_and_move(struct folio *src, struct folio *dst,
 }
 
 /*
- * Obtain the lock on page, remove all ptes and migrate the page
- * to the newly allocated page in newpage.
+ * Obtain the lock on folio, remove all ptes and migrate the folio
+ * to the newly allocated folio in dst.
  */
 static int unmap_and_move(new_page_t get_new_page,
 				   free_page_t put_new_page,
-				   unsigned long private, struct page *page,
+				   unsigned long private, struct folio *src,
 				   int force, enum migrate_mode mode,
 				   enum migrate_reason reason,
 				   struct list_head *ret)
 {
-	struct folio *dst, *src = page_folio(page);
+	struct folio *dst;
 	int rc = MIGRATEPAGE_SUCCESS;
 	struct page *newpage = NULL;
 
-	if (!thp_migration_supported() && PageTransHuge(page))
+	if (!thp_migration_supported() && folio_test_transhuge(src))
 		return -ENOSYS;
 
-	if (page_count(page) == 1) {
-		/* Page was freed from under us. So we are done. */
-		ClearPageActive(page);
-		ClearPageUnevictable(page);
+	if (folio_ref_count(src) == 1) {
+		/* Folio was freed from under us. So we are done. */
+		folio_clear_active(src);
+		folio_clear_unevictable(src);
 		/* free_pages_prepare() will clear PG_isolated. */
 		goto out;
 	}
 
-	newpage = get_new_page(page, private);
+	newpage = get_new_page(&src->page, private);
 	if (!newpage)
 		return -ENOMEM;
 	dst = page_folio(newpage);
 
-	newpage->private = 0;
+	dst->private = 0;
 	rc = __unmap_and_move(src, dst, force, mode);
 	if (rc == MIGRATEPAGE_SUCCESS)
-		set_page_owner_migrate_reason(newpage, reason);
+		set_page_owner_migrate_reason(&dst->page, reason);
 
 out:
 	if (rc != -EAGAIN) {
 		/*
-		 * A page that has been migrated has all references
-		 * removed and will be freed. A page that has not been
+		 * A folio that has been migrated has all references
+		 * removed and will be freed. A folio that has not been
 		 * migrated will have kept its references and be restored.
 		 */
-		list_del(&page->lru);
+		list_del(&src->lru);
 	}
 
 	/*
 	 * If migration is successful, releases reference grabbed during
-	 * isolation. Otherwise, restore the page to right list unless
+	 * isolation. Otherwise, restore the folio to right list unless
 	 * we want to retry.
 	 */
 	if (rc == MIGRATEPAGE_SUCCESS) {
 		/*
-		 * Compaction can migrate also non-LRU pages which are
+		 * Compaction can migrate also non-LRU folios which are
 		 * not accounted to NR_ISOLATED_*. They can be recognized
-		 * as __PageMovable
+		 * as __folio_test_movable
 		 */
-		if (likely(!__PageMovable(page)))
-			mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
-					page_is_file_lru(page), -thp_nr_pages(page));
+		if (likely(!__folio_test_movable(src)))
+			mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
+					folio_is_file_lru(src), -folio_nr_pages(src));
 
 		if (reason != MR_MEMORY_FAILURE)
 			/*
-			 * We release the page in page_handle_poison.
+			 * We release the folio in page_handle_poison.
 			 */
-			put_page(page);
+			folio_put(src);
 	} else {
 		if (rc != -EAGAIN)
-			list_add_tail(&page->lru, ret);
+			list_add_tail(&src->lru, ret);
 
 		if (put_new_page)
-			put_new_page(newpage, private);
+			put_new_page(&dst->page, private);
 		else
-			put_page(newpage);
+			folio_put(dst);
 	}
 
 	return rc;
@@ -1459,7 +1459,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 						&ret_pages);
 			else
 				rc = unmap_and_move(get_new_page, put_new_page,
-						private, page, pass > 2, mode,
+						private, page_folio(page), pass > 2, mode,
 						reason, &ret_pages);
 			/*
 			 * The rules are:
-- 
2.35.1

[PATCH 2/2] migrate: convert migrate_pages() to use folios

[Huang Ying]

Quite straightforward, the page functions are converted to
corresponding folio functions.  Same for comments.

THP specific code are converted to be large folio.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
---
 mm/migrate.c | 201 +++++++++++++++++++++++++++------------------------
 1 file changed, 107 insertions(+), 94 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index f6dd749dd2f8..b41289ef3b65 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1373,218 +1373,231 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	return rc;
 }
 
-static inline int try_split_thp(struct page *page, struct list_head *split_pages)
+static inline int try_split_folio(struct folio *folio, struct list_head *split_folios)
 {
 	int rc;
 
-	lock_page(page);
-	rc = split_huge_page_to_list(page, split_pages);
-	unlock_page(page);
+	folio_lock(folio);
+	rc = split_folio_to_list(folio, split_folios);
+	folio_unlock(folio);
 	if (!rc)
-		list_move_tail(&page->lru, split_pages);
+		list_move_tail(&folio->lru, split_folios);
 
 	return rc;
 }
 
 /*
- * migrate_pages - migrate the pages specified in a list, to the free pages
+ * migrate_pages - migrate the folios specified in a list, to the free folios
  *		   supplied as the target for the page migration
  *
- * @from:		The list of pages to be migrated.
- * @get_new_page:	The function used to allocate free pages to be used
- *			as the target of the page migration.
- * @put_new_page:	The function used to free target pages if migration
+ * @from:		The list of folios to be migrated.
+ * @get_new_page:	The function used to allocate free folios to be used
+ *			as the target of the folio migration.
+ * @put_new_page:	The function used to free target folios if migration
  *			fails, or NULL if no special handling is necessary.
  * @private:		Private data to be passed on to get_new_page()
  * @mode:		The migration mode that specifies the constraints for
- *			page migration, if any.
- * @reason:		The reason for page migration.
- * @ret_succeeded:	Set to the number of normal pages migrated successfully if
+ *			folio migration, if any.
+ * @reason:		The reason for folio migration.
+ * @ret_succeeded:	Set to the number of folios migrated successfully if
  *			the caller passes a non-NULL pointer.
  *
- * The function returns after 10 attempts or if no pages are movable any more
- * because the list has become empty or no retryable pages exist any more.
- * It is caller's responsibility to call putback_movable_pages() to return pages
+ * The function returns after 10 attempts or if no folios are movable any more
+ * because the list has become empty or no retryable folios exist any more.
+ * It is caller's responsibility to call putback_movable_pages() to return folios
  * to the LRU or free list only if ret != 0.
  *
- * Returns the number of {normal page, THP, hugetlb} that were not migrated, or
- * an error code. The number of THP splits will be considered as the number of
- * non-migrated THP, no matter how many subpages of the THP are migrated successfully.
+ * Returns the number of {normal folio, large folio, hugetlb} that were not
+ * migrated, or an error code. The number of large folio splits will be
+ * considered as the number of non-migrated large folio, no matter how many
+ * split folios of the large folio are migrated successfully.
  */
 int migrate_pages(struct list_head *from, new_page_t get_new_page,
 		free_page_t put_new_page, unsigned long private,
 		enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
 {
 	int retry = 1;
+	int large_retry = 1;
 	int thp_retry = 1;
 	int nr_failed = 0;
 	int nr_failed_pages = 0;
 	int nr_retry_pages = 0;
 	int nr_succeeded = 0;
 	int nr_thp_succeeded = 0;
+	int nr_large_failed = 0;
 	int nr_thp_failed = 0;
 	int nr_thp_split = 0;
 	int pass = 0;
+	bool is_large = false;
 	bool is_thp = false;
-	struct page *page;
-	struct page *page2;
-	int rc, nr_subpages;
-	LIST_HEAD(ret_pages);
-	LIST_HEAD(thp_split_pages);
+	struct folio *folio, *folio2;
+	int rc, nr_pages;
+	LIST_HEAD(ret_folios);
+	LIST_HEAD(split_folios);
 	bool nosplit = (reason == MR_NUMA_MISPLACED);
-	bool no_subpage_counting = false;
+	bool no_split_folio_counting = false;
 
 	trace_mm_migrate_pages_start(mode, reason);
 
-thp_subpage_migration:
-	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
+split_folio_migration:
+	for (pass = 0; pass < 10 && (retry || large_retry); pass++) {
 		retry = 0;
+		large_retry = 0;
 		thp_retry = 0;
 		nr_retry_pages = 0;
 
-		list_for_each_entry_safe(page, page2, from, lru) {
+		list_for_each_entry_safe(folio, folio2, from, lru) {
 			/*
-			 * THP statistics is based on the source huge page.
-			 * Capture required information that might get lost
-			 * during migration.
+			 * large folio statistics is based on the source large
+			 * folio. Capture required information that might get
+			 * lost during migration.
 			 */
-			is_thp = PageTransHuge(page) && !PageHuge(page);
-			nr_subpages = compound_nr(page);
+			is_large = folio_test_large(folio) && !folio_test_hugetlb(folio);
+			is_thp = is_large && folio_test_pmd_mappable(folio);
+			nr_pages = folio_nr_pages(folio);
 			cond_resched();
 
-			if (PageHuge(page))
+			if (folio_test_hugetlb(folio))
 				rc = unmap_and_move_huge_page(get_new_page,
-						put_new_page, private, page,
-						pass > 2, mode, reason,
-						&ret_pages);
+						put_new_page, private,
+						&folio->page, pass > 2, mode,
+						reason,
+						&ret_folios);
 			else
 				rc = unmap_and_move(get_new_page, put_new_page,
-						private, page_folio(page), pass > 2, mode,
-						reason, &ret_pages);
+						private, folio, pass > 2, mode,
+						reason, &ret_folios);
 			/*
 			 * The rules are:
-			 *	Success: non hugetlb page will be freed, hugetlb
-			 *		 page will be put back
+			 *	Success: non hugetlb folio will be freed, hugetlb
+			 *		 folio will be put back
 			 *	-EAGAIN: stay on the from list
 			 *	-ENOMEM: stay on the from list
 			 *	-ENOSYS: stay on the from list
-			 *	Other errno: put on ret_pages list then splice to
+			 *	Other errno: put on ret_folios list then splice to
 			 *		     from list
 			 */
 			switch(rc) {
 			/*
-			 * THP migration might be unsupported or the
-			 * allocation could've failed so we should
-			 * retry on the same page with the THP split
-			 * to base pages.
+			 * Large folio migration might be unsupported or
+			 * the allocation could've failed so we should retry
+			 * on the same folio with the large folio split
+			 * to normal folios.
 			 *
-			 * Sub-pages are put in thp_split_pages, and
+			 * Split folios are put in split_folios, and
 			 * we will migrate them after the rest of the
 			 * list is processed.
 			 */
 			case -ENOSYS:
-				/* THP migration is unsupported */
-				if (is_thp) {
-					nr_thp_failed++;
-					if (!try_split_thp(page, &thp_split_pages)) {
-						nr_thp_split++;
+				/* Large folio migration is unsupported */
+				if (is_large) {
+					nr_large_failed++;
+					nr_thp_failed += is_thp;
+					if (!try_split_folio(folio, &split_folios)) {
+						nr_thp_split += is_thp;
 						break;
 					}
 				/* Hugetlb migration is unsupported */
-				} else if (!no_subpage_counting) {
+				} else if (!no_split_folio_counting) {
 					nr_failed++;
 				}
 
-				nr_failed_pages += nr_subpages;
-				list_move_tail(&page->lru, &ret_pages);
+				nr_failed_pages += nr_pages;
+				list_move_tail(&folio->lru, &ret_folios);
 				break;
 			case -ENOMEM:
 				/*
 				 * When memory is low, don't bother to try to migrate
-				 * other pages, just exit.
+				 * other folios, just exit.
 				 */
-				if (is_thp) {
-					nr_thp_failed++;
-					/* THP NUMA faulting doesn't split THP to retry. */
-					if (!nosplit && !try_split_thp(page, &thp_split_pages)) {
-						nr_thp_split++;
+				if (is_large) {
+					nr_large_failed++;
+					nr_thp_failed += is_thp;
+					/* Large folio NUMA faulting doesn't split to retry. */
+					if (!nosplit && !try_split_folio(folio, &split_folios)) {
+						nr_thp_split += is_thp;
 						break;
 					}
-				} else if (!no_subpage_counting) {
+				} else if (!no_split_folio_counting) {
 					nr_failed++;
 				}
 
-				nr_failed_pages += nr_subpages + nr_retry_pages;
+				nr_failed_pages += nr_pages + nr_retry_pages;
 				/*
-				 * There might be some subpages of fail-to-migrate THPs
-				 * left in thp_split_pages list. Move them back to migration
+				 * There might be some split folios of fail-to-migrate large
+				 * folios left in split_folios list. Move them back to migration
 				 * list so that they could be put back to the right list by
-				 * the caller otherwise the page refcnt will be leaked.
+				 * the caller otherwise the folio refcnt will be leaked.
 				 */
-				list_splice_init(&thp_split_pages, from);
+				list_splice_init(&split_folios, from);
 				/* nr_failed isn't updated for not used */
+				nr_large_failed += large_retry;
 				nr_thp_failed += thp_retry;
 				goto out;
 			case -EAGAIN:
-				if (is_thp)
-					thp_retry++;
-				else if (!no_subpage_counting)
+				if (is_large) {
+					large_retry++;
+					thp_retry += is_thp;
+				} else if (!no_split_folio_counting) {
 					retry++;
-				nr_retry_pages += nr_subpages;
+				}
+				nr_retry_pages += nr_pages;
 				break;
 			case MIGRATEPAGE_SUCCESS:
-				nr_succeeded += nr_subpages;
-				if (is_thp)
-					nr_thp_succeeded++;
+				nr_succeeded += nr_pages;
+				nr_thp_succeeded += is_thp;
 				break;
 			default:
 				/*
 				 * Permanent failure (-EBUSY, etc.):
-				 * unlike -EAGAIN case, the failed page is
-				 * removed from migration page list and not
+				 * unlike -EAGAIN case, the failed folio is
+				 * removed from migration folio list and not
 				 * retried in the next outer loop.
 				 */
-				if (is_thp)
-					nr_thp_failed++;
-				else if (!no_subpage_counting)
+				if (is_large) {
+					nr_large_failed++;
+					nr_thp_failed += is_thp;
+				} else if (!no_split_folio_counting) {
 					nr_failed++;
+				}
 
-				nr_failed_pages += nr_subpages;
+				nr_failed_pages += nr_pages;
 				break;
 			}
 		}
 	}
 	nr_failed += retry;
+	nr_large_failed += large_retry;
 	nr_thp_failed += thp_retry;
 	nr_failed_pages += nr_retry_pages;
 	/*
-	 * Try to migrate subpages of fail-to-migrate THPs, no nr_failed
-	 * counting in this round, since all subpages of a THP is counted
-	 * as 1 failure in the first round.
+	 * Try to migrate split folios of fail-to-migrate large folios, no
+	 * nr_failed counting in this round, since all split folios of a
+	 * large folio is counted as 1 failure in the first round.
 	 */
-	if (!list_empty(&thp_split_pages)) {
+	if (!list_empty(&split_folios)) {
 		/*
-		 * Move non-migrated pages (after 10 retries) to ret_pages
+		 * Move non-migrated folios (after 10 retries) to ret_folios
 		 * to avoid migrating them again.
 		 */
-		list_splice_init(from, &ret_pages);
-		list_splice_init(&thp_split_pages, from);
-		no_subpage_counting = true;
+		list_splice_init(from, &ret_folios);
+		list_splice_init(&split_folios, from);
+		no_split_folio_counting = true;
 		retry = 1;
-		goto thp_subpage_migration;
+		goto split_folio_migration;
 	}
 
-	rc = nr_failed + nr_thp_failed;
+	rc = nr_failed + nr_large_failed;
 out:
 	/*
-	 * Put the permanent failure page back to migration list, they
+	 * Put the permanent failure folio back to migration list, they
 	 * will be put back to the right list by the caller.
 	 */
-	list_splice(&ret_pages, from);
+	list_splice(&ret_folios, from);
 
 	/*
-	 * Return 0 in case all subpages of fail-to-migrate THPs are
-	 * migrated successfully.
+	 * Return 0 in case all split folios of fail-to-migrate large folios
+	 * are migrated successfully.
 	 */
 	if (list_empty(from))
 		rc = 0;
-- 
2.35.1

Re: [PATCH 1/2] migrate: convert unmap_and_move() to use folios

[Baolin Wang]

On 11/4/2022 4:30 PM, Huang Ying wrote:
> Quite straightforward, the page functions are converted to
> corresponding folio functions.  Same for comments.
>

LGTM. Please feel free to add:
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>

> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Matthew Wilcox <willy@infradead.org>
> ---
>   mm/migrate.c | 54 ++++++++++++++++++++++++++--------------------------
>   1 file changed, 27 insertions(+), 27 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index dff333593a8a..f6dd749dd2f8 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1150,79 +1150,79 @@ static int __unmap_and_move(struct folio *src, struct folio *dst,
>   }
>   
>   /*
> - * Obtain the lock on page, remove all ptes and migrate the page
> - * to the newly allocated page in newpage.
> + * Obtain the lock on folio, remove all ptes and migrate the folio
> + * to the newly allocated folio in dst.
>    */
>   static int unmap_and_move(new_page_t get_new_page,
>   				   free_page_t put_new_page,
> -				   unsigned long private, struct page *page,
> +				   unsigned long private, struct folio *src,
>   				   int force, enum migrate_mode mode,
>   				   enum migrate_reason reason,
>   				   struct list_head *ret)
>   {
> -	struct folio *dst, *src = page_folio(page);
> +	struct folio *dst;
>   	int rc = MIGRATEPAGE_SUCCESS;
>   	struct page *newpage = NULL;
>   
> -	if (!thp_migration_supported() && PageTransHuge(page))
> +	if (!thp_migration_supported() && folio_test_transhuge(src))
>   		return -ENOSYS;
>   
> -	if (page_count(page) == 1) {
> -		/* Page was freed from under us. So we are done. */
> -		ClearPageActive(page);
> -		ClearPageUnevictable(page);
> +	if (folio_ref_count(src) == 1) {
> +		/* Folio was freed from under us. So we are done. */
> +		folio_clear_active(src);
> +		folio_clear_unevictable(src);
>   		/* free_pages_prepare() will clear PG_isolated. */
>   		goto out;
>   	}
>   
> -	newpage = get_new_page(page, private);
> +	newpage = get_new_page(&src->page, private);
>   	if (!newpage)
>   		return -ENOMEM;
>   	dst = page_folio(newpage);
>   
> -	newpage->private = 0;
> +	dst->private = 0;
>   	rc = __unmap_and_move(src, dst, force, mode);
>   	if (rc == MIGRATEPAGE_SUCCESS)
> -		set_page_owner_migrate_reason(newpage, reason);
> +		set_page_owner_migrate_reason(&dst->page, reason);
>   
>   out:
>   	if (rc != -EAGAIN) {
>   		/*
> -		 * A page that has been migrated has all references
> -		 * removed and will be freed. A page that has not been
> +		 * A folio that has been migrated has all references
> +		 * removed and will be freed. A folio that has not been
>   		 * migrated will have kept its references and be restored.
>   		 */
> -		list_del(&page->lru);
> +		list_del(&src->lru);
>   	}
>   
>   	/*
>   	 * If migration is successful, releases reference grabbed during
> -	 * isolation. Otherwise, restore the page to right list unless
> +	 * isolation. Otherwise, restore the folio to right list unless
>   	 * we want to retry.
>   	 */
>   	if (rc == MIGRATEPAGE_SUCCESS) {
>   		/*
> -		 * Compaction can migrate also non-LRU pages which are
> +		 * Compaction can migrate also non-LRU folios which are
>   		 * not accounted to NR_ISOLATED_*. They can be recognized
> -		 * as __PageMovable
> +		 * as __folio_test_movable
>   		 */
> -		if (likely(!__PageMovable(page)))
> -			mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
> -					page_is_file_lru(page), -thp_nr_pages(page));
> +		if (likely(!__folio_test_movable(src)))
> +			mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
> +					folio_is_file_lru(src), -folio_nr_pages(src));
>   
>   		if (reason != MR_MEMORY_FAILURE)
>   			/*
> -			 * We release the page in page_handle_poison.
> +			 * We release the folio in page_handle_poison.
>   			 */
> -			put_page(page);
> +			folio_put(src);
>   	} else {
>   		if (rc != -EAGAIN)
> -			list_add_tail(&page->lru, ret);
> +			list_add_tail(&src->lru, ret);
>   
>   		if (put_new_page)
> -			put_new_page(newpage, private);
> +			put_new_page(&dst->page, private);
>   		else
> -			put_page(newpage);
> +			folio_put(dst);
>   	}
>   
>   	return rc;
> @@ -1459,7 +1459,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   						&ret_pages);
>   			else
>   				rc = unmap_and_move(get_new_page, put_new_page,
> -						private, page, pass > 2, mode,
> +						private, page_folio(page), pass > 2, mode,
>   						reason, &ret_pages);
>   			/*
>   			 * The rules are:

Re: [PATCH 2/2] migrate: convert migrate_pages() to use folios

[Baolin Wang]

On 11/4/2022 4:30 PM, Huang Ying wrote:
> Quite straightforward, the page functions are converted to
> corresponding folio functions.  Same for comments.
> 
> THP specific code are converted to be large folio.
> 
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Matthew Wilcox <willy@infradead.org>
> ---
>   mm/migrate.c | 201 +++++++++++++++++++++++++++------------------------
>   1 file changed, 107 insertions(+), 94 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index f6dd749dd2f8..b41289ef3b65 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1373,218 +1373,231 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>   	return rc;
>   }
>   
> -static inline int try_split_thp(struct page *page, struct list_head *split_pages)
> +static inline int try_split_folio(struct folio *folio, struct list_head *split_folios)
>   {
>   	int rc;
>   
> -	lock_page(page);
> -	rc = split_huge_page_to_list(page, split_pages);
> -	unlock_page(page);
> +	folio_lock(folio);
> +	rc = split_folio_to_list(folio, split_folios);
> +	folio_unlock(folio);
>   	if (!rc)
> -		list_move_tail(&page->lru, split_pages);
> +		list_move_tail(&folio->lru, split_folios);
>   
>   	return rc;
>   }
>   
>   /*
> - * migrate_pages - migrate the pages specified in a list, to the free pages
> + * migrate_pages - migrate the folios specified in a list, to the free folios
>    *		   supplied as the target for the page migration
>    *
> - * @from:		The list of pages to be migrated.
> - * @get_new_page:	The function used to allocate free pages to be used
> - *			as the target of the page migration.
> - * @put_new_page:	The function used to free target pages if migration
> + * @from:		The list of folios to be migrated.
> + * @get_new_page:	The function used to allocate free folios to be used
> + *			as the target of the folio migration.
> + * @put_new_page:	The function used to free target folios if migration
>    *			fails, or NULL if no special handling is necessary.
>    * @private:		Private data to be passed on to get_new_page()
>    * @mode:		The migration mode that specifies the constraints for
> - *			page migration, if any.
> - * @reason:		The reason for page migration.
> - * @ret_succeeded:	Set to the number of normal pages migrated successfully if
> + *			folio migration, if any.
> + * @reason:		The reason for folio migration.
> + * @ret_succeeded:	Set to the number of folios migrated successfully if
>    *			the caller passes a non-NULL pointer.
>    *
> - * The function returns after 10 attempts or if no pages are movable any more
> - * because the list has become empty or no retryable pages exist any more.
> - * It is caller's responsibility to call putback_movable_pages() to return pages
> + * The function returns after 10 attempts or if no folios are movable any more
> + * because the list has become empty or no retryable folios exist any more.
> + * It is caller's responsibility to call putback_movable_pages() to return folios
>    * to the LRU or free list only if ret != 0.
>    *
> - * Returns the number of {normal page, THP, hugetlb} that were not migrated, or
> - * an error code. The number of THP splits will be considered as the number of
> - * non-migrated THP, no matter how many subpages of the THP are migrated successfully.
> + * Returns the number of {normal folio, large folio, hugetlb} that were not
> + * migrated, or an error code. The number of large folio splits will be
> + * considered as the number of non-migrated large folio, no matter how many
> + * split folios of the large folio are migrated successfully.
>    */
>   int migrate_pages(struct list_head *from, new_page_t get_new_page,
>   		free_page_t put_new_page, unsigned long private,
>   		enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
>   {
>   	int retry = 1;
> +	int large_retry = 1;
>   	int thp_retry = 1;
>   	int nr_failed = 0;
>   	int nr_failed_pages = 0;
>   	int nr_retry_pages = 0;
>   	int nr_succeeded = 0;
>   	int nr_thp_succeeded = 0;
> +	int nr_large_failed = 0;
>   	int nr_thp_failed = 0;
>   	int nr_thp_split = 0;
>   	int pass = 0;
> +	bool is_large = false;
>   	bool is_thp = false;
> -	struct page *page;
> -	struct page *page2;
> -	int rc, nr_subpages;
> -	LIST_HEAD(ret_pages);
> -	LIST_HEAD(thp_split_pages);
> +	struct folio *folio, *folio2;
> +	int rc, nr_pages;
> +	LIST_HEAD(ret_folios);
> +	LIST_HEAD(split_folios);
>   	bool nosplit = (reason == MR_NUMA_MISPLACED);
> -	bool no_subpage_counting = false;
> +	bool no_split_folio_counting = false;
>   
>   	trace_mm_migrate_pages_start(mode, reason);
>   
> -thp_subpage_migration:
> -	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
> +split_folio_migration:
> +	for (pass = 0; pass < 10 && (retry || large_retry); pass++) {
>   		retry = 0;
> +		large_retry = 0;
>   		thp_retry = 0;
>   		nr_retry_pages = 0;
>   
> -		list_for_each_entry_safe(page, page2, from, lru) {
> +		list_for_each_entry_safe(folio, folio2, from, lru) {
>   			/*
> -			 * THP statistics is based on the source huge page.
> -			 * Capture required information that might get lost
> -			 * during migration.
> +			 * large folio statistics is based on the source large

Nit: s/large/Large

> +			 * folio. Capture required information that might get
> +			 * lost during migration.
>   			 */
> -			is_thp = PageTransHuge(page) && !PageHuge(page);
> -			nr_subpages = compound_nr(page);
> +			is_large = folio_test_large(folio) && !folio_test_hugetlb(folio);
> +			is_thp = is_large && folio_test_pmd_mappable(folio);
> +			nr_pages = folio_nr_pages(folio);
>   			cond_resched();
>   
> -			if (PageHuge(page))
> +			if (folio_test_hugetlb(folio))
>   				rc = unmap_and_move_huge_page(get_new_page,
> -						put_new_page, private, page,
> -						pass > 2, mode, reason,
> -						&ret_pages);
> +						put_new_page, private,
> +						&folio->page, pass > 2, mode,
> +						reason,
> +						&ret_folios);
>   			else
>   				rc = unmap_and_move(get_new_page, put_new_page,
> -						private, page_folio(page), pass > 2, mode,
> -						reason, &ret_pages);
> +						private, folio, pass > 2, mode,
> +						reason, &ret_folios);
>   			/*
>   			 * The rules are:
> -			 *	Success: non hugetlb page will be freed, hugetlb
> -			 *		 page will be put back
> +			 *	Success: non hugetlb folio will be freed, hugetlb
> +			 *		 folio will be put back
>   			 *	-EAGAIN: stay on the from list
>   			 *	-ENOMEM: stay on the from list
>   			 *	-ENOSYS: stay on the from list
> -			 *	Other errno: put on ret_pages list then splice to
> +			 *	Other errno: put on ret_folios list then splice to
>   			 *		     from list
>   			 */
>   			switch(rc) {
>   			/*
> -			 * THP migration might be unsupported or the
> -			 * allocation could've failed so we should
> -			 * retry on the same page with the THP split
> -			 * to base pages.
> +			 * Large folio migration might be unsupported or
> +			 * the allocation could've failed so we should retry
> +			 * on the same folio with the large folio split
> +			 * to normal folios.
>   			 *
> -			 * Sub-pages are put in thp_split_pages, and
> +			 * Split folios are put in split_folios, and
>   			 * we will migrate them after the rest of the
>   			 * list is processed.
>   			 */
>   			case -ENOSYS:
> -				/* THP migration is unsupported */
> -				if (is_thp) {
> -					nr_thp_failed++;
> -					if (!try_split_thp(page, &thp_split_pages)) {
> -						nr_thp_split++;
> +				/* Large folio migration is unsupported */
> +				if (is_large) {
> +					nr_large_failed++;
> +					nr_thp_failed += is_thp;
> +					if (!try_split_folio(folio, &split_folios)) {
> +						nr_thp_split += is_thp;
>   						break;
>   					}
>   				/* Hugetlb migration is unsupported */
> -				} else if (!no_subpage_counting) {
> +				} else if (!no_split_folio_counting) {
>   					nr_failed++;
>   				}
>   
> -				nr_failed_pages += nr_subpages;
> -				list_move_tail(&page->lru, &ret_pages);
> +				nr_failed_pages += nr_pages;
> +				list_move_tail(&folio->lru, &ret_folios);
>   				break;
>   			case -ENOMEM:
>   				/*
>   				 * When memory is low, don't bother to try to migrate
> -				 * other pages, just exit.
> +				 * other folios, just exit.
>   				 */
> -				if (is_thp) {
> -					nr_thp_failed++;
> -					/* THP NUMA faulting doesn't split THP to retry. */
> -					if (!nosplit && !try_split_thp(page, &thp_split_pages)) {
> -						nr_thp_split++;
> +				if (is_large) {
> +					nr_large_failed++;
> +					nr_thp_failed += is_thp;
> +					/* Large folio NUMA faulting doesn't split to retry. */
> +					if (!nosplit && !try_split_folio(folio, &split_folios)) {

I am not sure if need to add a is_thp validation before calling 
try_split_folio()?

BTW, you should rebase on the mm-unstable branch, since I've added a 
retry for THP split.

> +						nr_thp_split += is_thp;
>   						break;
>   					}
> -				} else if (!no_subpage_counting) {
> +				} else if (!no_split_folio_counting) {
>   					nr_failed++;
>   				}
>   
> -				nr_failed_pages += nr_subpages + nr_retry_pages;
> +				nr_failed_pages += nr_pages + nr_retry_pages;
>   				/*
> -				 * There might be some subpages of fail-to-migrate THPs
> -				 * left in thp_split_pages list. Move them back to migration
> +				 * There might be some split folios of fail-to-migrate large
> +				 * folios left in split_folios list. Move them back to migration
>   				 * list so that they could be put back to the right list by
> -				 * the caller otherwise the page refcnt will be leaked.
> +				 * the caller otherwise the folio refcnt will be leaked.
>   				 */
> -				list_splice_init(&thp_split_pages, from);
> +				list_splice_init(&split_folios, from);
>   				/* nr_failed isn't updated for not used */
> +				nr_large_failed += large_retry;
>   				nr_thp_failed += thp_retry;
>   				goto out;
>   			case -EAGAIN:
> -				if (is_thp)
> -					thp_retry++;
> -				else if (!no_subpage_counting)
> +				if (is_large) {
> +					large_retry++;
> +					thp_retry += is_thp;
> +				} else if (!no_split_folio_counting) {
>   					retry++;
> -				nr_retry_pages += nr_subpages;
> +				}
> +				nr_retry_pages += nr_pages;
>   				break;
>   			case MIGRATEPAGE_SUCCESS:
> -				nr_succeeded += nr_subpages;
> -				if (is_thp)
> -					nr_thp_succeeded++;
> +				nr_succeeded += nr_pages;
> +				nr_thp_succeeded += is_thp;
>   				break;
>   			default:
>   				/*
>   				 * Permanent failure (-EBUSY, etc.):
> -				 * unlike -EAGAIN case, the failed page is
> -				 * removed from migration page list and not
> +				 * unlike -EAGAIN case, the failed folio is
> +				 * removed from migration folio list and not
>   				 * retried in the next outer loop.
>   				 */
> -				if (is_thp)
> -					nr_thp_failed++;
> -				else if (!no_subpage_counting)
> +				if (is_large) {
> +					nr_large_failed++;
> +					nr_thp_failed += is_thp;
> +				} else if (!no_split_folio_counting) {
>   					nr_failed++;
> +				}
>   
> -				nr_failed_pages += nr_subpages;
> +				nr_failed_pages += nr_pages;
>   				break;
>   			}
>   		}
>   	}
>   	nr_failed += retry;
> +	nr_large_failed += large_retry;
>   	nr_thp_failed += thp_retry;
>   	nr_failed_pages += nr_retry_pages;
>   	/*
> -	 * Try to migrate subpages of fail-to-migrate THPs, no nr_failed
> -	 * counting in this round, since all subpages of a THP is counted
> -	 * as 1 failure in the first round.
> +	 * Try to migrate split folios of fail-to-migrate large folios, no
> +	 * nr_failed counting in this round, since all split folios of a
> +	 * large folio is counted as 1 failure in the first round.
>   	 */
> -	if (!list_empty(&thp_split_pages)) {
> +	if (!list_empty(&split_folios)) {
>   		/*
> -		 * Move non-migrated pages (after 10 retries) to ret_pages
> +		 * Move non-migrated folios (after 10 retries) to ret_folios
>   		 * to avoid migrating them again.
>   		 */
> -		list_splice_init(from, &ret_pages);
> -		list_splice_init(&thp_split_pages, from);
> -		no_subpage_counting = true;
> +		list_splice_init(from, &ret_folios);
> +		list_splice_init(&split_folios, from);
> +		no_split_folio_counting = true;
>   		retry = 1;
> -		goto thp_subpage_migration;
> +		goto split_folio_migration;
>   	}
>   
> -	rc = nr_failed + nr_thp_failed;
> +	rc = nr_failed + nr_large_failed;
>   out:
>   	/*
> -	 * Put the permanent failure page back to migration list, they
> +	 * Put the permanent failure folio back to migration list, they
>   	 * will be put back to the right list by the caller.
>   	 */
> -	list_splice(&ret_pages, from);
> +	list_splice(&ret_folios, from);
>   
>   	/*
> -	 * Return 0 in case all subpages of fail-to-migrate THPs are
> -	 * migrated successfully.
> +	 * Return 0 in case all split folios of fail-to-migrate large folios
> +	 * are migrated successfully.
>   	 */
>   	if (list_empty(from))
>   		rc = 0;

Re: [PATCH 1/2] migrate: convert unmap_and_move() to use folios

[Matthew Wilcox]

On Fri, Nov 04, 2022 at 04:30:19PM +0800, Huang Ying wrote:
> Quite straightforward, the page functions are converted to
> corresponding folio functions.  Same for comments.

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Re: [PATCH 1/2] migrate: convert unmap_and_move() to use folios

[Zi Yan]

[-- Attachment #1: Type: text/plain, Size: 674 bytes --]

On 4 Nov 2022, at 4:30, Huang Ying wrote:

> Quite straightforward, the page functions are converted to
> corresponding folio functions.  Same for comments.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Matthew Wilcox <willy@infradead.org>
> ---
>  mm/migrate.c | 54 ++++++++++++++++++++++++++--------------------------
>  1 file changed, 27 insertions(+), 27 deletions(-)
>
LGTM. Thanks. Reviewed-by: Zi Yan <ziy@nvidia.com>

--
Best Regards,
Yan, Zi

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 854 bytes --]

Re: [PATCH 1/2] migrate: convert unmap_and_move() to use folios

[Yang Shi]

On Fri, Nov 4, 2022 at 1:31 AM Huang Ying <ying.huang@intel.com> wrote:
>
> Quite straightforward, the page functions are converted to
> corresponding folio functions.  Same for comments.

Reviewed-by: Yang Shi <shy828301@gmail.com>

>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Matthew Wilcox <willy@infradead.org>
> ---
>  mm/migrate.c | 54 ++++++++++++++++++++++++++--------------------------
>  1 file changed, 27 insertions(+), 27 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index dff333593a8a..f6dd749dd2f8 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1150,79 +1150,79 @@ static int __unmap_and_move(struct folio *src, struct folio *dst,
>  }
>
>  /*
> - * Obtain the lock on page, remove all ptes and migrate the page
> - * to the newly allocated page in newpage.
> + * Obtain the lock on folio, remove all ptes and migrate the folio
> + * to the newly allocated folio in dst.
>   */
>  static int unmap_and_move(new_page_t get_new_page,
>                                    free_page_t put_new_page,
> -                                  unsigned long private, struct page *page,
> +                                  unsigned long private, struct folio *src,
>                                    int force, enum migrate_mode mode,
>                                    enum migrate_reason reason,
>                                    struct list_head *ret)
>  {
> -       struct folio *dst, *src = page_folio(page);
> +       struct folio *dst;
>         int rc = MIGRATEPAGE_SUCCESS;
>         struct page *newpage = NULL;
>
> -       if (!thp_migration_supported() && PageTransHuge(page))
> +       if (!thp_migration_supported() && folio_test_transhuge(src))
>                 return -ENOSYS;
>
> -       if (page_count(page) == 1) {
> -               /* Page was freed from under us. So we are done. */
> -               ClearPageActive(page);
> -               ClearPageUnevictable(page);
> +       if (folio_ref_count(src) == 1) {
> +               /* Folio was freed from under us. So we are done. */
> +               folio_clear_active(src);
> +               folio_clear_unevictable(src);
>                 /* free_pages_prepare() will clear PG_isolated. */
>                 goto out;
>         }
>
> -       newpage = get_new_page(page, private);
> +       newpage = get_new_page(&src->page, private);
>         if (!newpage)
>                 return -ENOMEM;
>         dst = page_folio(newpage);
>
> -       newpage->private = 0;
> +       dst->private = 0;
>         rc = __unmap_and_move(src, dst, force, mode);
>         if (rc == MIGRATEPAGE_SUCCESS)
> -               set_page_owner_migrate_reason(newpage, reason);
> +               set_page_owner_migrate_reason(&dst->page, reason);
>
>  out:
>         if (rc != -EAGAIN) {
>                 /*
> -                * A page that has been migrated has all references
> -                * removed and will be freed. A page that has not been
> +                * A folio that has been migrated has all references
> +                * removed and will be freed. A folio that has not been
>                  * migrated will have kept its references and be restored.
>                  */
> -               list_del(&page->lru);
> +               list_del(&src->lru);
>         }
>
>         /*
>          * If migration is successful, releases reference grabbed during
> -        * isolation. Otherwise, restore the page to right list unless
> +        * isolation. Otherwise, restore the folio to right list unless
>          * we want to retry.
>          */
>         if (rc == MIGRATEPAGE_SUCCESS) {
>                 /*
> -                * Compaction can migrate also non-LRU pages which are
> +                * Compaction can migrate also non-LRU folios which are
>                  * not accounted to NR_ISOLATED_*. They can be recognized
> -                * as __PageMovable
> +                * as __folio_test_movable
>                  */
> -               if (likely(!__PageMovable(page)))
> -                       mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
> -                                       page_is_file_lru(page), -thp_nr_pages(page));
> +               if (likely(!__folio_test_movable(src)))
> +                       mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
> +                                       folio_is_file_lru(src), -folio_nr_pages(src));
>
>                 if (reason != MR_MEMORY_FAILURE)
>                         /*
> -                        * We release the page in page_handle_poison.
> +                        * We release the folio in page_handle_poison.
>                          */
> -                       put_page(page);
> +                       folio_put(src);
>         } else {
>                 if (rc != -EAGAIN)
> -                       list_add_tail(&page->lru, ret);
> +                       list_add_tail(&src->lru, ret);
>
>                 if (put_new_page)
> -                       put_new_page(newpage, private);
> +                       put_new_page(&dst->page, private);
>                 else
> -                       put_page(newpage);
> +                       folio_put(dst);
>         }
>
>         return rc;
> @@ -1459,7 +1459,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>                                                 &ret_pages);
>                         else
>                                 rc = unmap_and_move(get_new_page, put_new_page,
> -                                               private, page, pass > 2, mode,
> +                                               private, page_folio(page), pass > 2, mode,
>                                                 reason, &ret_pages);
>                         /*
>                          * The rules are:
> --
> 2.35.1
>

Re: [PATCH 2/2] migrate: convert migrate_pages() to use folios

[Huang, Ying]

Baolin Wang <baolin.wang@linux.alibaba.com> writes:

> On 11/4/2022 4:30 PM, Huang Ying wrote:
>> Quite straightforward, the page functions are converted to
>> corresponding folio functions.  Same for comments.
>> THP specific code are converted to be large folio.
>> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Zi Yan <ziy@nvidia.com>
>> Cc: Yang Shi <shy828301@gmail.com>
>> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
>> Cc: Oscar Salvador <osalvador@suse.de>
>> Cc: Matthew Wilcox <willy@infradead.org>
>> ---
>>   mm/migrate.c | 201 +++++++++++++++++++++++++++------------------------
>>   1 file changed, 107 insertions(+), 94 deletions(-)
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index f6dd749dd2f8..b41289ef3b65 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1373,218 +1373,231 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>>   	return rc;
>>   }
>>   -static inline int try_split_thp(struct page *page, struct
>> list_head *split_pages)
>> +static inline int try_split_folio(struct folio *folio, struct list_head *split_folios)
>>   {
>>   	int rc;
>>   -	lock_page(page);
>> -	rc = split_huge_page_to_list(page, split_pages);
>> -	unlock_page(page);
>> +	folio_lock(folio);
>> +	rc = split_folio_to_list(folio, split_folios);
>> +	folio_unlock(folio);
>>   	if (!rc)
>> -		list_move_tail(&page->lru, split_pages);
>> +		list_move_tail(&folio->lru, split_folios);
>>     	return rc;
>>   }
>>     /*
>> - * migrate_pages - migrate the pages specified in a list, to the free pages
>> + * migrate_pages - migrate the folios specified in a list, to the free folios
>>    *		   supplied as the target for the page migration
>>    *
>> - * @from:		The list of pages to be migrated.
>> - * @get_new_page:	The function used to allocate free pages to be used
>> - *			as the target of the page migration.
>> - * @put_new_page:	The function used to free target pages if migration
>> + * @from:		The list of folios to be migrated.
>> + * @get_new_page:	The function used to allocate free folios to be used
>> + *			as the target of the folio migration.
>> + * @put_new_page:	The function used to free target folios if migration
>>    *			fails, or NULL if no special handling is necessary.
>>    * @private:		Private data to be passed on to get_new_page()
>>    * @mode:		The migration mode that specifies the constraints for
>> - *			page migration, if any.
>> - * @reason:		The reason for page migration.
>> - * @ret_succeeded:	Set to the number of normal pages migrated successfully if
>> + *			folio migration, if any.
>> + * @reason:		The reason for folio migration.
>> + * @ret_succeeded:	Set to the number of folios migrated successfully if
>>    *			the caller passes a non-NULL pointer.
>>    *
>> - * The function returns after 10 attempts or if no pages are movable any more
>> - * because the list has become empty or no retryable pages exist any more.
>> - * It is caller's responsibility to call putback_movable_pages() to return pages
>> + * The function returns after 10 attempts or if no folios are movable any more
>> + * because the list has become empty or no retryable folios exist any more.
>> + * It is caller's responsibility to call putback_movable_pages() to return folios
>>    * to the LRU or free list only if ret != 0.
>>    *
>> - * Returns the number of {normal page, THP, hugetlb} that were not migrated, or
>> - * an error code. The number of THP splits will be considered as the number of
>> - * non-migrated THP, no matter how many subpages of the THP are migrated successfully.
>> + * Returns the number of {normal folio, large folio, hugetlb} that were not
>> + * migrated, or an error code. The number of large folio splits will be
>> + * considered as the number of non-migrated large folio, no matter how many
>> + * split folios of the large folio are migrated successfully.
>>    */
>>   int migrate_pages(struct list_head *from, new_page_t get_new_page,
>>   		free_page_t put_new_page, unsigned long private,
>>   		enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
>>   {
>>   	int retry = 1;
>> +	int large_retry = 1;
>>   	int thp_retry = 1;
>>   	int nr_failed = 0;
>>   	int nr_failed_pages = 0;
>>   	int nr_retry_pages = 0;
>>   	int nr_succeeded = 0;
>>   	int nr_thp_succeeded = 0;
>> +	int nr_large_failed = 0;
>>   	int nr_thp_failed = 0;
>>   	int nr_thp_split = 0;
>>   	int pass = 0;
>> +	bool is_large = false;
>>   	bool is_thp = false;
>> -	struct page *page;
>> -	struct page *page2;
>> -	int rc, nr_subpages;
>> -	LIST_HEAD(ret_pages);
>> -	LIST_HEAD(thp_split_pages);
>> +	struct folio *folio, *folio2;
>> +	int rc, nr_pages;
>> +	LIST_HEAD(ret_folios);
>> +	LIST_HEAD(split_folios);
>>   	bool nosplit = (reason == MR_NUMA_MISPLACED);
>> -	bool no_subpage_counting = false;
>> +	bool no_split_folio_counting = false;
>>     	trace_mm_migrate_pages_start(mode, reason);
>>   -thp_subpage_migration:
>> -	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
>> +split_folio_migration:
>> +	for (pass = 0; pass < 10 && (retry || large_retry); pass++) {
>>   		retry = 0;
>> +		large_retry = 0;
>>   		thp_retry = 0;
>>   		nr_retry_pages = 0;
>>   -		list_for_each_entry_safe(page, page2, from, lru) {
>> +		list_for_each_entry_safe(folio, folio2, from, lru) {
>>   			/*
>> -			 * THP statistics is based on the source huge page.
>> -			 * Capture required information that might get lost
>> -			 * during migration.
>> +			 * large folio statistics is based on the source large
>
> Nit: s/large/Large

Thanks.  Will change this.

>> +			 * folio. Capture required information that might get
>> +			 * lost during migration.
>>   			 */
>> -			is_thp = PageTransHuge(page) && !PageHuge(page);
>> -			nr_subpages = compound_nr(page);
>> +			is_large = folio_test_large(folio) && !folio_test_hugetlb(folio);
>> +			is_thp = is_large && folio_test_pmd_mappable(folio);
>> +			nr_pages = folio_nr_pages(folio);
>>   			cond_resched();
>>   -			if (PageHuge(page))
>> +			if (folio_test_hugetlb(folio))
>>   				rc = unmap_and_move_huge_page(get_new_page,
>> -						put_new_page, private, page,
>> -						pass > 2, mode, reason,
>> -						&ret_pages);
>> +						put_new_page, private,
>> +						&folio->page, pass > 2, mode,
>> +						reason,
>> +						&ret_folios);
>>   			else
>>   				rc = unmap_and_move(get_new_page, put_new_page,
>> -						private, page_folio(page), pass > 2, mode,
>> -						reason, &ret_pages);
>> +						private, folio, pass > 2, mode,
>> +						reason, &ret_folios);
>>   			/*
>>   			 * The rules are:
>> -			 *	Success: non hugetlb page will be freed, hugetlb
>> -			 *		 page will be put back
>> +			 *	Success: non hugetlb folio will be freed, hugetlb
>> +			 *		 folio will be put back
>>   			 *	-EAGAIN: stay on the from list
>>   			 *	-ENOMEM: stay on the from list
>>   			 *	-ENOSYS: stay on the from list
>> -			 *	Other errno: put on ret_pages list then splice to
>> +			 *	Other errno: put on ret_folios list then splice to
>>   			 *		     from list
>>   			 */
>>   			switch(rc) {
>>   			/*
>> -			 * THP migration might be unsupported or the
>> -			 * allocation could've failed so we should
>> -			 * retry on the same page with the THP split
>> -			 * to base pages.
>> +			 * Large folio migration might be unsupported or
>> +			 * the allocation could've failed so we should retry
>> +			 * on the same folio with the large folio split
>> +			 * to normal folios.
>>   			 *
>> -			 * Sub-pages are put in thp_split_pages, and
>> +			 * Split folios are put in split_folios, and
>>   			 * we will migrate them after the rest of the
>>   			 * list is processed.
>>   			 */
>>   			case -ENOSYS:
>> -				/* THP migration is unsupported */
>> -				if (is_thp) {
>> -					nr_thp_failed++;
>> -					if (!try_split_thp(page, &thp_split_pages)) {
>> -						nr_thp_split++;
>> +				/* Large folio migration is unsupported */
>> +				if (is_large) {
>> +					nr_large_failed++;
>> +					nr_thp_failed += is_thp;
>> +					if (!try_split_folio(folio, &split_folios)) {
>> +						nr_thp_split += is_thp;
>>   						break;
>>   					}
>>   				/* Hugetlb migration is unsupported */
>> -				} else if (!no_subpage_counting) {
>> +				} else if (!no_split_folio_counting) {
>>   					nr_failed++;
>>   				}
>>   -				nr_failed_pages += nr_subpages;
>> -				list_move_tail(&page->lru, &ret_pages);
>> +				nr_failed_pages += nr_pages;
>> +				list_move_tail(&folio->lru, &ret_folios);
>>   				break;
>>   			case -ENOMEM:
>>   				/*
>>   				 * When memory is low, don't bother to try to migrate
>> -				 * other pages, just exit.
>> +				 * other folios, just exit.
>>   				 */
>> -				if (is_thp) {
>> -					nr_thp_failed++;
>> -					/* THP NUMA faulting doesn't split THP to retry. */
>> -					if (!nosplit && !try_split_thp(page, &thp_split_pages)) {
>> -						nr_thp_split++;
>> +				if (is_large) {
>> +					nr_large_failed++;
>> +					nr_thp_failed += is_thp;
>> +					/* Large folio NUMA faulting doesn't split to retry. */
>> +					if (!nosplit && !try_split_folio(folio, &split_folios)) {
>
> I am not sure if need to add a is_thp validation before calling
> try_split_folio()?

IIUC try_split_folio() can deal with large folio with arbitrary order now.

> BTW, you should rebase on the mm-unstable branch, since I've added a
> retry for THP split.

Yes.  Andrew remind me too.

Best Regards,
Huang, Ying

>> +						nr_thp_split += is_thp;
>>   						break;
>>   					}
>> -				} else if (!no_subpage_counting) {
>> +				} else if (!no_split_folio_counting) {
>>   					nr_failed++;
>>   				}
>>   -				nr_failed_pages += nr_subpages +
>> nr_retry_pages;
>> +				nr_failed_pages += nr_pages + nr_retry_pages;
>>   				/*
>> -				 * There might be some subpages of fail-to-migrate THPs
>> -				 * left in thp_split_pages list. Move them back to migration
>> +				 * There might be some split folios of fail-to-migrate large
>> +				 * folios left in split_folios list. Move them back to migration
>>   				 * list so that they could be put back to the right list by
>> -				 * the caller otherwise the page refcnt will be leaked.
>> +				 * the caller otherwise the folio refcnt will be leaked.
>>   				 */
>> -				list_splice_init(&thp_split_pages, from);
>> +				list_splice_init(&split_folios, from);
>>   				/* nr_failed isn't updated for not used */
>> +				nr_large_failed += large_retry;
>>   				nr_thp_failed += thp_retry;
>>   				goto out;
>>   			case -EAGAIN:
>> -				if (is_thp)
>> -					thp_retry++;
>> -				else if (!no_subpage_counting)
>> +				if (is_large) {
>> +					large_retry++;
>> +					thp_retry += is_thp;
>> +				} else if (!no_split_folio_counting) {
>>   					retry++;
>> -				nr_retry_pages += nr_subpages;
>> +				}
>> +				nr_retry_pages += nr_pages;
>>   				break;
>>   			case MIGRATEPAGE_SUCCESS:
>> -				nr_succeeded += nr_subpages;
>> -				if (is_thp)
>> -					nr_thp_succeeded++;
>> +				nr_succeeded += nr_pages;
>> +				nr_thp_succeeded += is_thp;
>>   				break;
>>   			default:
>>   				/*
>>   				 * Permanent failure (-EBUSY, etc.):
>> -				 * unlike -EAGAIN case, the failed page is
>> -				 * removed from migration page list and not
>> +				 * unlike -EAGAIN case, the failed folio is
>> +				 * removed from migration folio list and not
>>   				 * retried in the next outer loop.
>>   				 */
>> -				if (is_thp)
>> -					nr_thp_failed++;
>> -				else if (!no_subpage_counting)
>> +				if (is_large) {
>> +					nr_large_failed++;
>> +					nr_thp_failed += is_thp;
>> +				} else if (!no_split_folio_counting) {
>>   					nr_failed++;
>> +				}
>>   -				nr_failed_pages += nr_subpages;
>> +				nr_failed_pages += nr_pages;
>>   				break;
>>   			}
>>   		}
>>   	}
>>   	nr_failed += retry;
>> +	nr_large_failed += large_retry;
>>   	nr_thp_failed += thp_retry;
>>   	nr_failed_pages += nr_retry_pages;
>>   	/*
>> -	 * Try to migrate subpages of fail-to-migrate THPs, no nr_failed
>> -	 * counting in this round, since all subpages of a THP is counted
>> -	 * as 1 failure in the first round.
>> +	 * Try to migrate split folios of fail-to-migrate large folios, no
>> +	 * nr_failed counting in this round, since all split folios of a
>> +	 * large folio is counted as 1 failure in the first round.
>>   	 */
>> -	if (!list_empty(&thp_split_pages)) {
>> +	if (!list_empty(&split_folios)) {
>>   		/*
>> -		 * Move non-migrated pages (after 10 retries) to ret_pages
>> +		 * Move non-migrated folios (after 10 retries) to ret_folios
>>   		 * to avoid migrating them again.
>>   		 */
>> -		list_splice_init(from, &ret_pages);
>> -		list_splice_init(&thp_split_pages, from);
>> -		no_subpage_counting = true;
>> +		list_splice_init(from, &ret_folios);
>> +		list_splice_init(&split_folios, from);
>> +		no_split_folio_counting = true;
>>   		retry = 1;
>> -		goto thp_subpage_migration;
>> +		goto split_folio_migration;
>>   	}
>>   -	rc = nr_failed + nr_thp_failed;
>> +	rc = nr_failed + nr_large_failed;
>>   out:
>>   	/*
>> -	 * Put the permanent failure page back to migration list, they
>> +	 * Put the permanent failure folio back to migration list, they
>>   	 * will be put back to the right list by the caller.
>>   	 */
>> -	list_splice(&ret_pages, from);
>> +	list_splice(&ret_folios, from);
>>     	/*
>> -	 * Return 0 in case all subpages of fail-to-migrate THPs are
>> -	 * migrated successfully.
>> +	 * Return 0 in case all split folios of fail-to-migrate large folios
>> +	 * are migrated successfully.
>>   	 */
>>   	if (list_empty(from))
>>   		rc = 0;