Subject: [PATCH v3 09/29] m68k: introduce arch_zone_limits_init()

From: Mike Rapoport <[email-masked]>
Date: Sun, 11 Jan 2026 10:20:43 +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.

Since all variants of m68k add all memory to ZONE_DMA, it is possible to
use unified implementation for arch_zone_limits_init() that sets the end
of ZONE_DMA to memblock_end_of_DRAM().

Signed-off-by: Mike Rapoport (Microsoft) <[email-masked]>
---
 arch/m68k/mm/init.c     | 7 ++++++-
 arch/m68k/mm/mcfmmu.c   | 2 +-
 arch/m68k/mm/motorola.c | 2 +-
 arch/m68k/mm/sun3mmu.c  | 2 +-
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/m68k/mm/init.c b/arch/m68k/mm/init.c
index 488411af1b3f..6b1d9d2434b5 100644
--- a/arch/m68k/mm/init.c
+++ b/arch/m68k/mm/init.c
@@ -40,6 +40,11 @@
 void *empty_zero_page;
 EXPORT_SYMBOL(empty_zero_page);
 
+void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
+{
+	max_zone_pfns[ZONE_DMA] = PFN_DOWN(memblock_end_of_DRAM());
+}
+
 #ifdef CONFIG_MMU
 
 int m68k_virt_to_node_shift;
@@ -69,7 +74,7 @@ void __init paging_init(void)
 	high_memory = (void *) end_mem;
 
 	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
-	max_zone_pfn[ZONE_DMA] = end_mem >> PAGE_SHIFT;
+	arch_zone_limits_init(max_zone_pfn);
 	free_area_init(max_zone_pfn);
 }
 
diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c
index 19a75029036c..24a6f7bbd1ce 100644
--- a/arch/m68k/mm/mcfmmu.c
+++ b/arch/m68k/mm/mcfmmu.c
@@ -73,7 +73,7 @@ void __init paging_init(void)
 	}
 
 	current->mm = NULL;
-	max_zone_pfn[ZONE_DMA] = PFN_DOWN(_ramend);
+	arch_zone_limits_init(max_zone_pfn);
 	free_area_init(max_zone_pfn);
 }
 
diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 62283bc2ed79..d6ccd23caf61 100644
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -517,6 +517,6 @@ void __init paging_init(void)
 		if (node_present_pages(i))
 			node_set_state(i, N_NORMAL_MEMORY);
 
-	max_zone_pfn[ZONE_DMA] = memblock_end_of_DRAM();
+	arch_zone_limits_init(max_zone_pfn);
 	free_area_init(max_zone_pfn);
 }
diff --git a/arch/m68k/mm/sun3mmu.c b/arch/m68k/mm/sun3mmu.c
index 1ecf6bdd08bf..fdd69cc4240c 100644
--- a/arch/m68k/mm/sun3mmu.c
+++ b/arch/m68k/mm/sun3mmu.c
@@ -82,7 +82,7 @@ void __init paging_init(void)
 	current->mm = NULL;
 
 	/* memory sizing is a hack stolen from motorola.c..  hope it works for us */
-	max_zone_pfn[ZONE_DMA] = ((unsigned long)high_memory) >> PAGE_SHIFT;
+	arch_zone_limits_init(max_zone_pfn);
 
 	/* I really wish I knew why the following change made things better...  -- Sam */
 	free_area_init(max_zone_pfn);
-- 
2.51.0