arch, mm: consolidate initialization of nodes, zones and memory map

To initialize node, zone and memory map data structures every architecture
calls free_area_init() during setup_arch() and passes it an array of zone
limits.

Beside code duplication it creates "interesting" ordering cases between
allocation and initialization of hugetlb and the memory map.  Some
architectures allocate hugetlb pages very early in setup_arch() in certain
cases, some only create hugetlb CMA areas in setup_arch() and sometimes
hugetlb allocations happen mm_core_init().

With arch_zone_limits_init() helper available now on all architectures it
is no longer necessary to call free_area_init() from architecture setup
code.  Rather core MM initialization can call arch_zone_limits_init() in a
single place.

This allows to unify ordering of hugetlb vs memory map allocation and
initialization.

Remove the call to free_area_init() from architecture specific code and
place it in a new mm_core_init_early() function that is called immediately
after setup_arch().

After this refactoring it is possible to consolidate hugetlb allocations
and eliminate differences in ordering of hugetlb and memory map
initialization among different architectures.

As the first step of this consolidation move hugetlb_bootmem_alloc() to
mm_core_early_init().

Link: https://lkml.kernel.org/r/20260111082105.290734-24-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: rppt

arch/alpha/mm/init.c

@@ -220,17 +220,10 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
 }
 
 /*
- * paging_init() sets up the memory map.
+ * paging_init() initializes the kernel's ZERO_PGE.
  */
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
-
-	/* Initialize mem_map[].  */
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
-
-	/* Initialize the kernel's ZERO_PGE. */
 	memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE);
 }
 

arch/arc/mm/init.c

@@ -102,8 +102,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
  */
 void __init setup_arch_memory(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
 	setup_initial_init_mm(_text, _etext, _edata, _end);
 
 	/* first page of system - kernel .vector starts here */
@@ -158,9 +156,6 @@ void __init setup_arch_memory(void)
 	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);
 }
 
 void __init arch_mm_preinit(void)

arch/arm/mm/init.c

@@ -118,15 +118,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
 #endif
 }
 
-static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
-	unsigned long max_high)
-{
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
-}
-
 #ifdef CONFIG_HAVE_ARCH_PFN_VALID
 int pfn_valid(unsigned long pfn)
 {
@@ -222,13 +213,6 @@ void __init bootmem_init(void)
 	 * done after the fixed reservations
 	 */
 	sparse_init();
-
-	/*
-	 * Now free the memory - free_area_init needs
-	 * the sparse mem_map arrays initialized by sparse_init()
-	 * for memmap_init_zone(), otherwise all PFNs are invalid.
-	 */
-	zone_sizes_init(min_low_pfn, max_low_pfn, max_pfn);
 }
 
 /*

arch/arm64/mm/init.c

@@ -134,7 +134,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 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;
 	phys_addr_t __maybe_unused dt_zone_dma_limit;
 	phys_addr_t __maybe_unused dma32_phys_limit =
@@ -160,9 +159,6 @@ static void __init dma_limits_init(void)
 #endif
 	if (!arm64_dma_phys_limit)
 		arm64_dma_phys_limit = PHYS_MASK + 1;
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
 }
 
 int pfn_is_map_memory(unsigned long pfn)

arch/csky/kernel/setup.c

@@ -63,7 +63,6 @@ static void __init csky_memblock_init(void)
 {
 	unsigned long lowmem_size = PFN_DOWN(LOWMEM_LIMIT - PHYS_OFFSET_OFFSET);
 	unsigned long sseg_size = PFN_DOWN(SSEG_SIZE - PHYS_OFFSET_OFFSET);
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 	signed long size;
 
 	memblock_reserve(__pa(_start), _end - _start);
@@ -101,9 +100,6 @@ static void __init csky_memblock_init(void)
 	memblock_set_current_limit(PFN_PHYS(max_low_pfn));
 
 	dma_contiguous_reserve(0);
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 void __init setup_arch(char **cmdline_p)

arch/hexagon/mm/init.c

@@ -66,20 +66,8 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 }
 
-/*
- * In order to set up page allocator "nodes",
- * somebody has to call free_area_init() for UMA.
- *
- * In this mode, we only have one pg_data_t
- * structure: contig_mem_data.
- */
 static void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);  /*  sets up the zonelists and mem_map  */
-
 	/*
 	 * Set the init_mm descriptors "context" value to point to the
 	 * initial kernel segment table's physical address.

arch/loongarch/include/asm/pgtable.h

@@ -353,8 +353,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
 	return pte;
 }
 
-extern void paging_init(void);
-
 #define pte_none(pte)		(!(pte_val(pte) & ~_PAGE_GLOBAL))
 #define pte_present(pte)	(pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROTNONE))
 #define pte_no_exec(pte)	(pte_val(pte) & _PAGE_NO_EXEC)

arch/loongarch/kernel/setup.c

@@ -621,8 +621,6 @@ void __init setup_arch(char **cmdline_p)
 	prefill_possible_map();
 #endif
 
-	paging_init();
-
 #ifdef CONFIG_KASAN
 	kasan_init();
 #endif

arch/loongarch/mm/init.c

@@ -68,14 +68,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 }
 
-void __init paging_init(void)
-{
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
-}
-
 void __ref free_initmem(void)
 {
 	free_initmem_default(POISON_FREE_INITMEM);

arch/m68k/mm/init.c

@@ -69,13 +69,10 @@ void __init paging_init(void)
 	 * page_alloc get different views of the world.
 	 */
 	unsigned long end_mem = memory_end & PAGE_MASK;
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
 
 	high_memory = (void *) end_mem;
 
 	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 #endif /* CONFIG_MMU */