[PATCH 5/8] mm: Add a helper to accept page

[Kirill A. Shutemov]

Accept a given struct page and add it free list.

The help is useful for physical memory scanners that want to use free
unaccepted memory.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 mm/internal.h   |  8 ++++++++
 mm/page_alloc.c | 53 +++++++++++++++++++++++++++++++++++--------------
 2 files changed, 46 insertions(+), 15 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index b4d86436565b..d358535f8a7e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1578,4 +1578,12 @@ void unlink_file_vma_batch_init(struct unlink_vma_file_batch *);
 void unlink_file_vma_batch_add(struct unlink_vma_file_batch *, struct vm_area_struct *);
 void unlink_file_vma_batch_final(struct unlink_vma_file_batch *);
 
+#ifdef CONFIG_UNACCEPTED_MEMORY
+void accept_page(struct page *page);
+#else /* CONFIG_UNACCEPTED_MEMORY */
+static inline void accept_page(struct page *page)
+{
+}
+#endif /* CONFIG_UNACCEPTED_MEMORY */
+
 #endif	/* __MM_INTERNAL_H */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 34718852d576..5f33e92b0a55 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6953,11 +6953,46 @@ static void accept_page_memory(struct page *page, unsigned int order)
 	accept_memory(start, start + (PAGE_SIZE << order));
 }
 
+static void __accept_page(struct zone *zone, unsigned long *flags,
+			  struct page *page)
+{
+	bool last;
+
+	list_del(&page->lru);
+	last = list_empty(&zone->unaccepted_pages);
+
+	account_freepages(zone, -MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
+	__mod_zone_page_state(zone, NR_UNACCEPTED, -MAX_ORDER_NR_PAGES);
+	__ClearPageUnaccepted(page);
+	spin_unlock_irqrestore(&zone->lock, *flags);
+
+	accept_page_memory(page, MAX_PAGE_ORDER);
+
+	__free_pages_ok(page, MAX_PAGE_ORDER, FPI_TO_TAIL);
+
+	if (last)
+		static_branch_dec(&zones_with_unaccepted_pages);
+}
+
+void accept_page(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+	unsigned long flags;
+
+	spin_lock_irqsave(&zone->lock, flags);
+	if (!PageUnaccepted(page)) {
+		spin_unlock_irqrestore(&zone->lock, flags);
+		return;
+	}
+
+	/* Unlocks zone->lock */
+	__accept_page(zone, &flags, page);
+}
+
 static bool try_to_accept_memory_one(struct zone *zone)
 {
 	unsigned long flags;
 	struct page *page;
-	bool last;
 
 	spin_lock_irqsave(&zone->lock, flags);
 	page = list_first_entry_or_null(&zone->unaccepted_pages,
@@ -6967,20 +7002,8 @@ static bool try_to_accept_memory_one(struct zone *zone)
 		return false;
 	}
 
-	list_del(&page->lru);
-	last = list_empty(&zone->unaccepted_pages);
-
-	account_freepages(zone, -MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
-	__mod_zone_page_state(zone, NR_UNACCEPTED, -MAX_ORDER_NR_PAGES);
-	__ClearPageUnaccepted(page);
-	spin_unlock_irqrestore(&zone->lock, flags);
-
-	accept_page_memory(page, MAX_PAGE_ORDER);
-
-	__free_pages_ok(page, MAX_PAGE_ORDER, FPI_TO_TAIL);
-
-	if (last)
-		static_branch_dec(&zones_with_unaccepted_pages);
+	/* Unlocks zone->lock */
+	__accept_page(zone, &flags, page);
 
 	return true;
 }
-- 
2.43.0