[PATCH v2 2/4] mm: migrate: move the numamigrate_isolate_page() into do_numa_page()

[Baolin Wang]

Move the numamigrate_isolate_page() into do_numa_page() to simplify the
migrate_misplaced_page(), which now only focuses on page migration, and
it also serves as a preparation for supporting batch migration for
migrate_misplaced_page().

While we are at it, change the numamigrate_isolate_page() to boolean
type to make the return value more clear.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
 include/linux/migrate.h |  6 ++++++
 mm/huge_memory.c        |  7 +++++++
 mm/memory.c             |  7 +++++++
 mm/migrate.c            | 22 +++++++---------------
 4 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 711dd9412561..ddcd62ec2c12 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -144,12 +144,18 @@ 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);
+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)
 {
 	return -EAGAIN; /* can't migrate now */
 }
+
+static inline bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
+{
+	return false;
+}
 #endif /* CONFIG_NUMA_BALANCING */
 
 #ifdef CONFIG_MIGRATION
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4a9b34a89854..07149ead11e4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1496,6 +1496,7 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
 	int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
 	bool migrated = false, writable = false;
 	int flags = 0;
+	pg_data_t *pgdat;
 
 	vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 	if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
@@ -1545,6 +1546,12 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
 		goto migrate_fail;
 	}
 
+	pgdat = NODE_DATA(target_nid);
+	if (!numamigrate_isolate_page(pgdat, page)) {
+		put_page(page);
+		goto migrate_fail;
+	}
+
 	migrated = migrate_misplaced_page(page, vma, target_nid);
 	if (migrated) {
 		flags |= TNF_MIGRATED;
diff --git a/mm/memory.c b/mm/memory.c
index fc6f6b7a70e1..4e451b041488 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4769,6 +4769,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 	int target_nid;
 	pte_t pte, old_pte;
 	int flags = 0;
+	pg_data_t *pgdat;
 
 	/*
 	 * The "pte" at this point cannot be used safely without
@@ -4844,6 +4845,12 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 		goto migrate_fail;
 	}
 
+	pgdat = NODE_DATA(target_nid);
+	if (!numamigrate_isolate_page(pgdat, page)) {
+		put_page(page);
+		goto migrate_fail;
+	}
+
 	/* Migrate to the requested node */
 	if (migrate_misplaced_page(page, vma, target_nid)) {
 		page_nid = target_nid;
diff --git a/mm/migrate.c b/mm/migrate.c
index 9cc98fb1d6ec..0b2b69a2a7ab 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2478,7 +2478,7 @@ static struct folio *alloc_misplaced_dst_folio(struct folio *src,
 	return __folio_alloc_node(gfp, order, nid);
 }
 
-static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
+bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 {
 	int nr_pages = thp_nr_pages(page);
 	int order = compound_order(page);
@@ -2496,11 +2496,11 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 				break;
 		}
 		wakeup_kswapd(pgdat->node_zones + z, 0, order, ZONE_MOVABLE);
-		return 0;
+		return false;
 	}
 
 	if (!isolate_lru_page(page))
-		return 0;
+		return false;
 
 	mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_lru(page),
 			    nr_pages);
@@ -2511,7 +2511,7 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 	 * disappearing underneath us during migration.
 	 */
 	put_page(page);
-	return 1;
+	return true;
 }
 
 /*
@@ -2523,16 +2523,12 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
 			   int node)
 {
 	pg_data_t *pgdat = NODE_DATA(node);
-	int isolated;
+	int migrated = 1;
 	int nr_remaining;
 	unsigned int nr_succeeded;
 	LIST_HEAD(migratepages);
 	int nr_pages = thp_nr_pages(page);
 
-	isolated = numamigrate_isolate_page(pgdat, page);
-	if (!isolated)
-		goto out;
-
 	list_add(&page->lru, &migratepages);
 	nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio,
 				     NULL, node, MIGRATE_ASYNC,
@@ -2544,7 +2540,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
 					page_is_file_lru(page), -nr_pages);
 			putback_lru_page(page);
 		}
-		isolated = 0;
+		migrated = 0;
 	}
 	if (nr_succeeded) {
 		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
@@ -2553,11 +2549,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
 					    nr_succeeded);
 	}
 	BUG_ON(!list_empty(&migratepages));
-	return isolated;
-
-out:
-	put_page(page);
-	return 0;
+	return migrated;
 }
 #endif /* CONFIG_NUMA_BALANCING */
 #endif /* CONFIG_NUMA */
-- 
2.39.3