arch, mm: set max_mapnr when allocating memory map for FLATMEM

max_mapnr is essentially the size of the memory map for systems that use
FLATMEM. There is no reason to calculate it in each and every architecture
when it's anyway calculated in alloc_node_mem_map().

Drop setting of max_mapnr from architecture code and set it once in
alloc_node_mem_map().

While on it, move definition of mem_map and max_mapnr to mm/mm_init.c so
there won't be two copies for MMU and !MMU variants.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Mike Rapoport (Microsoft) <[e-mail]>
Acked-by: Dave Hansen <[e-mail]> [x86]
Tested-by: Mark Brown <[e-mail]>
Cc: Alexander Gordeev <[e-mail]>
Cc: Andreas Larsson <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Ard Biesheuvel <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Borislav Betkov <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Dinh Nguyen <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Gerald Schaefer <[e-mail]>
Cc: Guo Ren (csky) <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiaxun Yang <[e-mail]>
Cc: Johannes Berg <[e-mail]>
Cc: John Paul Adrian Glaubitz <[e-mail]>
Cc: Madhavan Srinivasan <[e-mail]>
Cc: Matt Turner <[e-mail]>
Cc: Max Filippov <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Michal Simek <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Cc: Richard Weinberger <[e-mail]>
Cc: Russel King <[e-mail]>
Cc: Stafford Horne <[e-mail]>
Cc: Thomas Bogendoerfer <[e-mail]>
Cc: Thomas Gleinxer <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Vineet Gupta <[e-mail]>
Cc: Will Deacon <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/alpha/mm/init.c

···
 void __init
 mem_init(void)
 {
-	set_max_mapnr(max_low_pfn);
 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 	memblock_free_all();
 }

arch/arc/mm/init.c

···
 
 	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
 	kmap_init();
-
-#else /* CONFIG_HIGHMEM */
-	/* pfn_valid() uses this when FLATMEM=y and HIGHMEM=n */
-	max_mapnr = max_low_pfn - min_low_pfn;
-
 #endif /* CONFIG_HIGHMEM */
 
 	free_area_init(max_zone_pfn);

arch/arm/mm/init.c

···
 	swiotlb_init(max_pfn > arm_dma_pfn_limit, SWIOTLB_VERBOSE);
 #endif
 
-	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
-
 #ifdef CONFIG_SA1111
 	/* now that our DMA memory is actually so designated, we can free it */
 	memblock_phys_free(PHYS_OFFSET, __pa(swapper_pg_dir) - PHYS_OFFSET);

arch/csky/mm/init.c

···
 {
 #ifdef CONFIG_HIGHMEM
 	unsigned long tmp;
-
-	set_max_mapnr(highend_pfn - ARCH_PFN_OFFSET);
-#else
-	set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);
 #endif
 	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 

arch/loongarch/mm/init.c

···
 
 void __init mem_init(void)
 {
-	max_mapnr = max_low_pfn;
 	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 
 	memblock_free_all();

arch/microblaze/mm/init.c

···
 	 *
 	 * min_low_pfn - the first page (mm/bootmem.c - node_boot_start)
 	 * max_low_pfn
-	 * max_mapnr - the first unused page (mm/bootmem.c - node_low_pfn)
 	 */
 
 	/* memory start is from the kernel end (aligned) to higher addr */
 	min_low_pfn = memory_start >> PAGE_SHIFT; /* minimum for allocation */
-	/* RAM is assumed contiguous */
-	max_mapnr = memory_size >> PAGE_SHIFT;
 	max_low_pfn = ((u64)memory_start + (u64)lowmem_size) >> PAGE_SHIFT;
 	max_pfn = ((u64)memory_start + (u64)memory_size) >> PAGE_SHIFT;
 
-	pr_info("%s: max_mapnr: %#lx\n", __func__, max_mapnr);
 	pr_info("%s: min_low_pfn: %#lx\n", __func__, min_low_pfn);
 	pr_info("%s: max_low_pfn: %#lx\n", __func__, max_low_pfn);
 	pr_info("%s: max_pfn: %#lx\n", __func__, max_pfn);

arch/mips/mm/init.c

···
 		       " %ldk highmem ignored\n",
 		       (highend_pfn - max_low_pfn) << (PAGE_SHIFT - 10));
 		max_zone_pfns[ZONE_HIGHMEM] = max_low_pfn;
-
-		max_mapnr = max_low_pfn;
-	} else if (highend_pfn) {
-		max_mapnr = highend_pfn;
-	} else {
-		max_mapnr = max_low_pfn;
 	}
-#else
-	max_mapnr = max_low_pfn;
 #endif
 	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 

arch/nios2/kernel/setup.c

···
 	*cmdline_p = boot_command_line;
 
 	find_limits(&min_low_pfn, &max_low_pfn, &max_pfn);
-	max_mapnr = max_low_pfn;
 
 	memblock_reserve(__pa_symbol(_stext), _end - _stext);
 #ifdef CONFIG_BLK_DEV_INITRD

arch/nios2/mm/init.c

···
 	pagetable_init();
 	pgd_current = swapper_pg_dir;
 
-	max_zone_pfn[ZONE_NORMAL] = max_mapnr;
+	max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
 
 	/* pass the memory from the bootmem allocator to the main allocator */
 	free_area_init(max_zone_pfn);

arch/openrisc/mm/init.c

···
 {
 	BUG_ON(!mem_map);
 
-	max_mapnr = max_low_pfn;
 	high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);
 
 	/* clear the zero-page */

arch/parisc/mm/init.c

···
 #endif
 
 	high_memory = __va((max_pfn << PAGE_SHIFT));
-	set_max_mapnr(max_low_pfn);
 	memblock_free_all();
 
 #ifdef CONFIG_PA11

arch/powerpc/kernel/setup-common.c

···
 
 	/* Parse memory topology */
 	mem_topology_setup();
-	/* Set max_mapnr before paging_init() */
-	set_max_mapnr(max_pfn);
 	high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);
 
 	/*

arch/riscv/mm/init.c

···
 	high_memory = (void *)(__va(PFN_PHYS(max_low_pfn)));
 
 	dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn));
-	set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);
 
 	reserve_initrd_mem();
 

arch/s390/mm/init.c

···
 	cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
 	cpumask_set_cpu(0, mm_cpumask(&init_mm));
 
-	set_max_mapnr(max_low_pfn);
         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 
 	pv_init();

arch/sh/mm/init.c

···
 	 */
 	max_low_pfn = max_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
 	min_low_pfn = __MEMORY_START >> PAGE_SHIFT;
-	set_max_mapnr(max_low_pfn - min_low_pfn);
 
 	nodes_clear(node_online_map);
 

arch/sparc/mm/init_32.c

···
 
 	taint_real_pages();
 
-	max_mapnr = last_valid_pfn - pfn_base;
 	high_memory = __va(max_low_pfn << PAGE_SHIFT);
 	memblock_free_all();
 

arch/um/include/shared/mem_user.h

···
 #define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
 
 extern unsigned long find_iomem(char *driver, unsigned long *len_out);
-extern void mem_total_pages(unsigned long physmem, unsigned long iomem);
 extern void setup_physmem(unsigned long start, unsigned long usable,
 			  unsigned long len);
 extern void map_memory(unsigned long virt, unsigned long phys,

arch/um/kernel/physmem.c

···
 unsigned long high_physmem;
 EXPORT_SYMBOL(high_physmem);
 
-void __init mem_total_pages(unsigned long physmem, unsigned long iomem)
-{
-	unsigned long phys_pages, iomem_pages, total_pages;
-
-	phys_pages  = physmem >> PAGE_SHIFT;
-	iomem_pages = iomem   >> PAGE_SHIFT;
-
-	total_pages = phys_pages + iomem_pages;
-
-	max_mapnr = total_pages;
-}
-
 void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
 		int r, int w, int x)
 {

arch/um/kernel/um_arch.c

···
 
 	stack_protections((unsigned long) init_task.stack);
 	setup_physmem(uml_physmem, uml_reserved, physmem_size);
-	mem_total_pages(physmem_size, iomem_size);
 	uml_dtb_init();
 	read_initrd();
 

arch/x86/mm/init_32.c

···
 
 	memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
 
-#ifdef CONFIG_FLATMEM
-	max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
-#endif
 	__vmalloc_start_set = true;
 
 	printk(KERN_NOTICE "%ldMB LOWMEM available.\n",

arch/xtensa/mm/init.c

···
 {
 	free_highpages();
 
-	max_mapnr = max_pfn - ARCH_PFN_OFFSET;
 	high_memory = (void *)__va(max_low_pfn << PAGE_SHIFT);
 
 	memblock_free_all();

include/asm-generic/memory_model.h

···
 #define __page_to_pfn(page)	((unsigned long)((page) - mem_map) + \
 				 ARCH_PFN_OFFSET)
 
+/* avoid <linux/mm.h> include hell */
+extern unsigned long max_mapnr;
+
 #ifndef pfn_valid
 static inline int pfn_valid(unsigned long pfn)
 {
-	/* avoid <linux/mm.h> include hell */
-	extern unsigned long max_mapnr;
 	unsigned long pfn_offset = ARCH_PFN_OFFSET;
 
 	return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;

include/linux/mm.h

···
 void mm_core_init(void);
 void init_mm_internals(void);
 
-#ifndef CONFIG_NUMA		/* Don't use mapnrs, do it properly */
-extern unsigned long max_mapnr;
-
-static inline void set_max_mapnr(unsigned long limit)
-{
-	max_mapnr = limit;
-}
-#else
-static inline void set_max_mapnr(unsigned long limit) { }
-#endif
-
 extern atomic_long_t _totalram_pages;
 static inline unsigned long totalram_pages(void)
 {

mm/memory.c

···
 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
 #endif
 
-#ifndef CONFIG_NUMA
-unsigned long max_mapnr;
-EXPORT_SYMBOL(max_mapnr);
-
-struct page *mem_map;
-EXPORT_SYMBOL(mem_map);
-#endif
-
 static vm_fault_t do_fault(struct vm_fault *vmf);
 static vm_fault_t do_anonymous_page(struct vm_fault *vmf);
 static bool vmf_pte_changed(struct vm_fault *vmf);

mm/mm_init.c

···
 
 #include <asm/setup.h>
 
+#ifndef CONFIG_NUMA
+unsigned long max_mapnr;
+EXPORT_SYMBOL(max_mapnr);
+
+struct page *mem_map;
+EXPORT_SYMBOL(mem_map);
+#endif
+
 #ifdef CONFIG_DEBUG_MEMORY_INIT
 int __meminitdata mminit_loglevel;
 
···
 	start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
 	offset = pgdat->node_start_pfn - start;
 	/*
-		 * The zone's endpoints aren't required to be MAX_PAGE_ORDER
+	 * The zone's endpoints aren't required to be MAX_PAGE_ORDER
 	 * aligned but the node_mem_map endpoints must be in order
 	 * for the buddy allocator to function correctly.
 	 */
···
 	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
 		 __func__, pgdat->node_id, (unsigned long)pgdat,
 		 (unsigned long)pgdat->node_mem_map);
-#ifndef CONFIG_NUMA
+
 	/* the global mem_map is just set as node 0's */
-	if (pgdat == NODE_DATA(0)) {
-		mem_map = NODE_DATA(0)->node_mem_map;
-		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
-			mem_map -= offset;
-	}
-#endif
+	WARN_ON(pgdat != NODE_DATA(0));
+
+	mem_map = pgdat->node_mem_map;
+	if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
+		mem_map -= offset;
+
+	max_mapnr = end - start;
 }
 #else
 static inline void alloc_node_mem_map(struct pglist_data *pgdat) { }

mm/nommu.c

···
 
 void *high_memory;
 EXPORT_SYMBOL(high_memory);
-struct page *mem_map;
-unsigned long max_mapnr;
-EXPORT_SYMBOL(max_mapnr);
 unsigned long highest_memmap_pfn;
 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
 int heap_stack_gap = 0;
 
 atomic_long_t mmap_pages_allocated;
 
-EXPORT_SYMBOL(mem_map);
 
 /* list of mapped, potentially shareable regions */
 static struct kmem_cache *vm_region_jar;