[RFC PATCH v4 05/27] mm: introduce folio_is_private_managed() unified predicate

[Gregory Price <gourry@gourry.net>]

Multiple mm/ subsystems already skip operations for ZONE_DEVICE folios,
and N_MEMORY_PRIVATE folios share the checkpoints for ZONE_DEVICE pages.

Add folio_is_private_managed() as a unified predicate that returns true
for folios on N_MEMORY_PRIVATE nodes or in ZONE_DEVICE.

This predicate replaces folio_is_zone_device at skip sites where both
folio types should be excluded from an MM operation.

At some locations, explicit zone_device vs private_node checks are more
appropriate when the operations between the two fundamentally differ.

The !CONFIG_NUMA stubs fall through to folio_is_zone_device() only,
preserving existing behavior when NUMA is disabled.

Signed-off-by: Gregory Price <gourry@gourry.net>
---
 include/linux/node_private.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/node_private.h b/include/linux/node_private.h
index 6a70ec39d569..7687a4cf990c 100644
--- a/include/linux/node_private.h
+++ b/include/linux/node_private.h
@@ -92,6 +92,16 @@ static inline bool page_is_private_node(struct page *page)
 	return node_state(page_to_nid(page), N_MEMORY_PRIVATE);
 }
 
+static inline bool folio_is_private_managed(struct folio *folio)
+{
+	return folio_is_zone_device(folio) || folio_is_private_node(folio);
+}
+
+static inline bool page_is_private_managed(struct page *page)
+{
+	return folio_is_private_managed(page_folio(page));
+}
+
 static inline const struct node_private_ops *
 folio_node_private_ops(struct folio *folio)
 {
@@ -146,6 +156,16 @@ static inline bool page_is_private_node(struct page *page)
 	return false;
 }
 
+static inline bool folio_is_private_managed(struct folio *folio)
+{
+	return folio_is_zone_device(folio);
+}
+
+static inline bool page_is_private_managed(struct page *page)
+{
+	return folio_is_private_managed(page_folio(page));
+}
+
 static inline const struct node_private_ops *
 folio_node_private_ops(struct folio *folio)
 {
-- 
2.53.0