[PATCH RFC 21/29] mm: rename PG_isolated to PG_movable_ops_isolated

[David Hildenbrand]

Let's rename the flag to make it clearer where it applies (not folios
...).

While at it, define the flag only with CONFIG_MIGRATION.

Signed-off-by: David Hildenbrand <david at redhat.com>
---
 include/linux/page-flags.h | 16 +++++++++++-----
 mm/compaction.c            |  2 +-
 mm/migrate.c               | 14 +++++++-------
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 016a6e6fa428a..aa48b05536bca 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -167,10 +167,9 @@ enum pageflags {
 	/* Remapped by swiotlb-xen. */
 	PG_xen_remapped = PG_owner_priv_1,
 
-	/* non-lru isolated movable page */
-	PG_isolated = PG_reclaim,
-
 #ifdef CONFIG_MIGRATION
+	/* movable_ops page that is isolated for migration */
+	PG_movable_ops_isolated = PG_reclaim,
 	/* this is a movable_ops page (for selected typed pages only) */
 	PG_movable_ops = PG_uptodate,
 #endif
@@ -1126,8 +1125,6 @@ static inline bool folio_contain_hwpoisoned_page(struct folio *folio)
 
 bool is_free_buddy_page(const struct page *page);
 
-PAGEFLAG(Isolated, isolated, PF_ANY);
-
 #ifdef CONFIG_MIGRATION
 /*
  * This page is migratable through movable_ops (for selected typed pages
@@ -1146,8 +1143,17 @@ PAGEFLAG(Isolated, isolated, PF_ANY);
  * page_has_movable_ops() instead.
  */
 PAGEFLAG(MovableOps, movable_ops, PF_NO_TAIL);
+/*
+ * A movable_ops page has this flag set while it is isolated for migration.
+ * This flag primarily protects against concurrent migration attempts.
+ *
+ * Once migration ended (success or failure), the flag is cleared. The
+ * flag is managed by the migration core.
+ */
+PAGEFLAG(MovableOpsIsolated, movable_ops_isolated, PF_NO_TAIL);
 #else
 PAGEFLAG_FALSE(MovableOps, movable_ops);
+PAGEFLAG_FALSE(MovableOpsIsolated, movable_ops_isolated);
 #endif
 
 /**
diff --git a/mm/compaction.c b/mm/compaction.c
index 86d671a520e91..809e4395cadfc 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1051,7 +1051,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 		if (!PageLRU(page)) {
 			/* Isolation will grab the page lock. */
 			if (unlikely(page_has_movable_ops(page)) &&
-					!PageIsolated(page)) {
+			    !PageMovableOpsIsolated(page)) {
 				if (locked) {
 					unlock_page_lruvec_irqrestore(locked, flags);
 					locked = NULL;
diff --git a/mm/migrate.c b/mm/migrate.c
index a36030de94f30..f87a998b696e2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -135,7 +135,7 @@ bool isolate_movable_ops_page(struct page *page, isolate_mode_t mode)
 		goto out_putfolio;
 
 	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
-	if (PageIsolated(page))
+	if (PageMovableOpsIsolated(page))
 		goto out_no_isolated;
 
 	mops = page_movable_ops(page);
@@ -146,8 +146,8 @@ bool isolate_movable_ops_page(struct page *page, isolate_mode_t mode)
 		goto out_no_isolated;
 
 	/* Driver shouldn't use the isolated flag */
-	VM_WARN_ON_ONCE_PAGE(PageIsolated(page), page);
-	SetPageIsolated(page);
+	VM_WARN_ON_ONCE_PAGE(PageMovableOpsIsolated(page), page);
+	SetPageMovableOpsIsolated(page);
 	folio_unlock(folio);
 
 	return true;
@@ -177,10 +177,10 @@ static void putback_movable_ops_page(struct page *page)
 	struct folio *folio = page_folio(page);
 
 	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
-	VM_WARN_ON_ONCE_PAGE(!PageIsolated(page), page);
+	VM_WARN_ON_ONCE_PAGE(!PageMovableOpsIsolated(page), page);
 	folio_lock(folio);
 	page_movable_ops(page)->putback_page(page);
-	ClearPageIsolated(page);
+	ClearPageMovableOpsIsolated(page);
 	folio_unlock(folio);
 	folio_put(folio);
 }
@@ -216,10 +216,10 @@ static int migrate_movable_ops_page(struct page *dst, struct page *src,
 	int rc = MIGRATEPAGE_SUCCESS;
 
 	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(src), src);
-	VM_WARN_ON_ONCE_PAGE(!PageIsolated(src), src);
+	VM_WARN_ON_ONCE_PAGE(!PageMovableOpsIsolated(src), src);
 	rc = page_movable_ops(src)->migrate_page(dst, src, mode);
 	if (rc == MIGRATEPAGE_SUCCESS)
-		ClearPageIsolated(src);
+		ClearPageMovableOpsIsolated(src);
 	return rc;
 }
 
-- 
2.49.0