[PATCH v2 3/4] mm: migrate: change migrate_misplaced_page() to support multiple pages migration

[Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>]

Expanding the migrate_misplaced_page() function to allow passing in a list
to support multiple pages migration as a preparation to support batch migration
for NUMA balancing as well as compound page NUMA balancing in future.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
 include/linux/migrate.h |  9 +++++----
 mm/huge_memory.c        |  5 ++++-
 mm/memory.c             |  4 +++-
 mm/migrate.c            | 26 ++++++++++----------------
 4 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index ddcd62ec2c12..87edce8e939d 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -142,12 +142,13 @@ const struct movable_operations *page_movable_ops(struct page *page)
 }
 
 #ifdef CONFIG_NUMA_BALANCING
-int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
-			   int node);
+int migrate_misplaced_page(struct list_head *migratepages, struct vm_area_struct *vma,
+			   int source_nid, int target_nid);
 bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page);
 #else
-static inline int migrate_misplaced_page(struct page *page,
-					 struct vm_area_struct *vma, int node)
+static inline int migrate_misplaced_page(struct list_head *migratepages,
+					 struct vm_area_struct *vma,
+					 int source_nid, int target_nid)
 {
 	return -EAGAIN; /* can't migrate now */
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 07149ead11e4..4401a3493544 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1497,6 +1497,7 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
 	bool migrated = false, writable = false;
 	int flags = 0;
 	pg_data_t *pgdat;
+	LIST_HEAD(migratepages);
 
 	vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 	if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
@@ -1552,7 +1553,9 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
 		goto migrate_fail;
 	}
 
-	migrated = migrate_misplaced_page(page, vma, target_nid);
+	list_add(&page->lru, &migratepages);
+	migrated = migrate_misplaced_page(&migratepages, vma,
+					  page_nid, target_nid);
 	if (migrated) {
 		flags |= TNF_MIGRATED;
 		page_nid = target_nid;
diff --git a/mm/memory.c b/mm/memory.c
index 4e451b041488..9e417e8dd5d5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4770,6 +4770,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 	pte_t pte, old_pte;
 	int flags = 0;
 	pg_data_t *pgdat;
+	LIST_HEAD(migratepages);
 
 	/*
 	 * The "pte" at this point cannot be used safely without
@@ -4851,8 +4852,9 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 		goto migrate_fail;
 	}
 
+	list_add(&page->lru, &migratepages);
 	/* Migrate to the requested node */
-	if (migrate_misplaced_page(page, vma, target_nid)) {
+	if (migrate_misplaced_page(&migratepages, vma, page_nid, target_nid)) {
 		page_nid = target_nid;
 		flags |= TNF_MIGRATED;
 	} else {
diff --git a/mm/migrate.c b/mm/migrate.c
index 0b2b69a2a7ab..fae7224b8e64 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2519,36 +2519,30 @@ bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
  * node. Caller is expected to have an elevated reference count on
  * the page that will be dropped by this function before returning.
  */
-int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
-			   int node)
+int migrate_misplaced_page(struct list_head *migratepages, struct vm_area_struct *vma,
+			   int source_nid, int target_nid)
 {
-	pg_data_t *pgdat = NODE_DATA(node);
+	pg_data_t *pgdat = NODE_DATA(target_nid);
 	int migrated = 1;
 	int nr_remaining;
 	unsigned int nr_succeeded;
-	LIST_HEAD(migratepages);
-	int nr_pages = thp_nr_pages(page);
 
-	list_add(&page->lru, &migratepages);
-	nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio,
-				     NULL, node, MIGRATE_ASYNC,
+	nr_remaining = migrate_pages(migratepages, alloc_misplaced_dst_folio,
+				     NULL, target_nid, MIGRATE_ASYNC,
 				     MR_NUMA_MISPLACED, &nr_succeeded);
 	if (nr_remaining) {
-		if (!list_empty(&migratepages)) {
-			list_del(&page->lru);
-			mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
-					page_is_file_lru(page), -nr_pages);
-			putback_lru_page(page);
-		}
+		if (!list_empty(migratepages))
+			putback_movable_pages(migratepages);
+
 		migrated = 0;
 	}
 	if (nr_succeeded) {
 		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
-		if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
+		if (!node_is_toptier(source_nid) && node_is_toptier(target_nid))
 			mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
 					    nr_succeeded);
 	}
-	BUG_ON(!list_empty(&migratepages));
+	BUG_ON(!list_empty(migratepages));
 	return migrated;
 }
 #endif /* CONFIG_NUMA_BALANCING */
-- 
2.39.3