Subject: [PATCH v2 04/28] arm64: introduce arch_zone_limits_init()

From: Mike Rapoport <[email-masked]>
Date: Fri, 2 Jan 2026 08:59:40 +0200

From: "Mike Rapoport (Microsoft)" <[email-masked]>

Move calculations of zone limits to a dedicated arch_zone_limits_init()
function.

Later MM core will use this function as an architecture specific callback
during nodes and zones initialization and thus there won't be a need to
call free_area_init() from every architecture.

While on it rename zone_sizes_init() to dma_limits_init() to better
reflect what that function does.

Signed-off-by: Mike Rapoport (Microsoft) <[email-masked]>
---
 arch/arm64/mm/init.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 524d34a0e921..06815d34cc11 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -118,7 +118,21 @@ static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit)
 	return min(zone_limit, memblock_end_of_DRAM() - 1) + 1;
 }
 
-static void __init zone_sizes_init(void)
+void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
+{
+	phys_addr_t __maybe_unused dma32_phys_limit =
+		max_zone_phys(DMA_BIT_MASK(32));
+
+#ifdef CONFIG_ZONE_DMA
+	max_zone_pfns[ZONE_DMA] = PFN_DOWN(max_zone_phys(zone_dma_limit));
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit);
+#endif
+	max_zone_pfns[ZONE_NORMAL] = max_pfn;
+}
+
+static void __init dma_limits_init(void)
 {
 	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
 	phys_addr_t __maybe_unused acpi_zone_dma_limit;
@@ -139,17 +153,15 @@ static void __init zone_sizes_init(void)
 	if (memblock_start_of_DRAM() < U32_MAX)
 		zone_dma_limit = min(zone_dma_limit, U32_MAX);
 	arm64_dma_phys_limit = max_zone_phys(zone_dma_limit);
-	max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit);
 #endif
 #ifdef CONFIG_ZONE_DMA32
-	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit);
 	if (!arm64_dma_phys_limit)
 		arm64_dma_phys_limit = dma32_phys_limit;
 #endif
 	if (!arm64_dma_phys_limit)
 		arm64_dma_phys_limit = PHYS_MASK + 1;
-	max_zone_pfns[ZONE_NORMAL] = max_pfn;
 
+	arch_zone_limits_init(max_zone_pfns);
 	free_area_init(max_zone_pfns);
 }
 
@@ -319,7 +331,7 @@ void __init bootmem_init(void)
 	 * done after the fixed reservations
 	 */
 	sparse_init();
-	zone_sizes_init();
+	dma_limits_init();
 
 	/*
 	 * Reserve the CMA area after arm64_dma_phys_limit was initialised.
-- 
2.51.0