linux-kernel - [PATCH 02/28] arc: introduce arch_zone_limits

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Message-ID: <20251228124001.3624742-3-rppt@kernel.org>
Date: Sun, 28 Dec 2025 14:39:32 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Alex Shi <alexs@...nel.org>,
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Subject: [PATCH 02/28] arc: introduce arch_zone_limits_init()

From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>

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.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
 arch/arc/mm/init.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index a73cc94f806e..ff7974d38011 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -75,6 +75,25 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
 		base, TO_MB(size), !in_use ? "Not used":"");
 }
 
+void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
+{
+	/*----------------- node/zones setup --------------------------*/
+	max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * max_high_pfn should be ok here for both HIGHMEM and HIGHMEM+PAE.
+	 * For HIGHMEM without PAE max_high_pfn should be less than
+	 * min_low_pfn to guarantee that these two regions don't overlap.
+	 * For PAE case highmem is greater than lowmem, so it is natural
+	 * to use max_high_pfn.
+	 *
+	 * In both cases, holes should be handled by pfn_valid().
+	 */
+	max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;
+#endif
+}
+
 /*
  * First memory setup routine called from setup_arch()
  * 1. setup swapper's mm @init_mm
@@ -122,9 +141,6 @@ void __init setup_arch_memory(void)
 
 	memblock_dump_all();
 
-	/*----------------- node/zones setup --------------------------*/
-	max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
-
 #ifdef CONFIG_HIGHMEM
 	/*
 	 * On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
@@ -139,21 +155,11 @@ void __init setup_arch_memory(void)
 	min_high_pfn = PFN_DOWN(high_mem_start);
 	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
 
-	/*
-	 * max_high_pfn should be ok here for both HIGHMEM and HIGHMEM+PAE.
-	 * For HIGHMEM without PAE max_high_pfn should be less than
-	 * min_low_pfn to guarantee that these two regions don't overlap.
-	 * For PAE case highmem is greater than lowmem, so it is natural
-	 * to use max_high_pfn.
-	 *
-	 * In both cases, holes should be handled by pfn_valid().
-	 */
-	max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;
-
 	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
 	kmap_init();
 #endif /* CONFIG_HIGHMEM */
 
+	arch_zone_limits_init(max_zone_pfn);
 	free_area_init(max_zone_pfn);
 }
 
-- 
2.51.0