linux-kernel - [PATCH 2/3] mm_zone: Generalise has_managed

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Message-Id: <bd002d2351074e57be1ca08f03f333debac658fb.1768230104.git.robin.murphy@arm.com>
Date: Mon, 12 Jan 2026 15:46:37 +0000
From: Robin Murphy <robin.murphy@....com>
To: m.szyprowski@...sung.com,
	akpm@...ux-foundation.org,
	vbabka@...e.cz,
	david@...nel.org
Cc: bhe@...hat.com,
	iommu@...ts.linux-foundation.org,
	linux-mm@...ck.org,
	vladimir.kondratiev@...ileye.com,
	s-adivi@...com,
	linux-kernel@...r.kernel.org,
	lorenzo.stoakes@...cle.com,
	Liam.Howlett@...cle.com,
	rppt@...nel.org,
	surenb@...gle.com,
	mhocko@...e.com,
	jackmanb@...gle.com,
	hannes@...xchg.org,
	ziy@...dia.com
Subject: [PATCH 2/3] mm_zone: Generalise has_managed_dma()

It would be useful to be able to check for potential DMA pages beyond
just ZONE_DMA - generalise the existing has_managed_dma() function to
allow checking other zones too.

Signed-off-by: Robin Murphy <robin.murphy@....com>
---
 include/linux/mmzone.h | 9 +++++----
 mm/page_alloc.c        | 8 ++------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 75ef7c9f9307..fc5d6c88d2f0 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1648,14 +1648,15 @@ static inline int is_highmem(const struct zone *zone)
 	return is_highmem_idx(zone_idx(zone));
 }
 
-#ifdef CONFIG_ZONE_DMA
-bool has_managed_dma(void);
-#else
+bool has_managed_zone(enum zone_type zone);
 static inline bool has_managed_dma(void)
 {
+#ifdef CONFIG_ZONE_DMA
+	return has_managed_zone(ZONE_DMA);
+#else
 	return false;
-}
 #endif
+}
 
 
 #ifndef CONFIG_NUMA
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 822e05f1a964..36ccc85c5073 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7418,20 +7418,16 @@ bool put_page_back_buddy(struct page *page)
 }
 #endif
 
-#ifdef CONFIG_ZONE_DMA
-bool has_managed_dma(void)
+bool has_managed_zone(enum zone_type zone)
 {
 	struct pglist_data *pgdat;
 
 	for_each_online_pgdat(pgdat) {
-		struct zone *zone = &pgdat->node_zones[ZONE_DMA];
-
-		if (managed_zone(zone))
+		if (managed_zone(&pgdat->node_zones[zone]))
 			return true;
 	}
 	return false;
 }
-#endif /* CONFIG_ZONE_DMA */
 
 #ifdef CONFIG_UNACCEPTED_MEMORY
 
-- 
2.34.1