[PATCH 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 NUMA
balancing.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
 include/linux/migrate.h |  6 ++++++
 mm/huge_memory.c        | 10 ++++++++++
 mm/memory.c             | 10 ++++++++++
 mm/migrate.c            | 16 ++++------------
 4 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 711dd9412561..7c5189043707 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);
+int 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 int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
+{
+	return -EAGAIN;
+}
 #endif /* CONFIG_NUMA_BALANCING */
 
 #ifdef CONFIG_MIGRATION
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index cb4432792b88..b7cc6828ce9e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1496,6 +1496,8 @@ 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;
+	int isolated;
 
 	vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 	if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
@@ -1540,11 +1542,19 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
 	spin_unlock(vmf->ptl);
 	writable = false;
 
+	pgdat = NODE_DATA(target_nid);
+	isolated = numamigrate_isolate_page(pgdat, page);
+	if (!isolated) {
+		put_page(page);
+		goto isolate_fail;
+	}
+
 	migrated = migrate_misplaced_page(page, vma, target_nid);
 	if (migrated) {
 		flags |= TNF_MIGRATED;
 		page_nid = target_nid;
 	} else {
+isolate_fail:
 		flags |= TNF_MIGRATE_FAIL;
 		vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 		if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
diff --git a/mm/memory.c b/mm/memory.c
index bee9b1e86ef0..01b1980d4fb7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4779,6 +4779,8 @@ 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;
+	int isolated;
 
 	/*
 	 * The "pte" at this point cannot be used safely without
@@ -4849,11 +4851,19 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 	pte_unmap_unlock(vmf->pte, vmf->ptl);
 	writable = false;
 
+	pgdat = NODE_DATA(target_nid);
+	isolated = numamigrate_isolate_page(pgdat, page);
+	if (!isolated) {
+		put_page(page);
+		goto isolate_fail;
+	}
+
 	/* Migrate to the requested node */
 	if (migrate_misplaced_page(page, vma, target_nid)) {
 		page_nid = target_nid;
 		flags |= TNF_MIGRATED;
 	} else {
+isolate_fail:
 		flags |= TNF_MIGRATE_FAIL;
 		vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
 					       vmf->address, &vmf->ptl);
diff --git a/mm/migrate.c b/mm/migrate.c
index 9cc98fb1d6ec..5eeeb2cda21c 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)
+int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 {
 	int nr_pages = thp_nr_pages(page);
 	int order = compound_order(page);
@@ -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