[PATCH] no arch-specific mem_map init

So, this patch started out with me trying to keep from passing contiguous,
node-specific mem_map into free_area_init_node() and cousins.  Instead, I
relied on some calls to pfn_to_page().

This works fine and dandy when all you need is the pgdat->node_mem_map to
do pfn_to_page().  However, the non-NUMA/DISCONTIG architectures use the
real, global mem_map[] instead of a node_mem_map in the pfn_to_page()
calculation.  So, I ended up effectively trying to initialize mem_map from
itself, when it was NULL.  That was bad, and caused some very pretty colors
on someone's screen when he tested it.

So, I had to make sure to initialize the global mem_map[] before calling
into free_area_init_node().  Then, I realized how many architectures do
this on their own, and have comments like this:

        /* XXX: MRB-remove - this doesn't seem sane, should this be done somewhere else ?*/
        mem_map = NODE_DATA(0)->node_mem_map;

The following patch does what my first one did (don't pass mem_map into the
init functions), incorporates Jesse Barnes' ia64 fixes on top of that, and
gets rid of all but one of the global mem_map initializations (parisc is
weird).  It also magically removes more code than it adds.  It could be
smaller, but I shamelessly added some comments. 

Boot-tested on ppc64, i386 (NUMAQ, plain SMP, laptop), UML (i386).
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/arm/mm/init.c

@@ -501,10 +501,6 @@ void __init paging_init(struct meminfo *mi, struct machine_desc *mdesc)
 				bdata->node_boot_start >> PAGE_SHIFT, zhole_size);
 	}
 
-#ifndef CONFIG_DISCONTIGMEM
-	mem_map = contig_page_data.node_mem_map;
-#endif
-
 	/*
 	 * finish off the bad pages once
 	 * the mem_map is initialised

arch/arm26/mm/init.c

@@ -309,8 +309,6 @@ void __init paging_init(struct meminfo *mi)
 	free_area_init_node(0, pgdat, zone_size,
 			bdata->node_boot_start >> PAGE_SHIFT, zhole_size);
 
-	mem_map = NODE_DATA(0)->node_mem_map;
-
 	/*
 	 * finish off the bad pages once
 	 * the mem_map is initialised

arch/cris/arch-v10/mm/init.c

@@ -184,7 +184,6 @@ paging_init(void)
 	 */
 
 	free_area_init_node(0, &contig_page_data, zones_size, PAGE_OFFSET >> PAGE_SHIFT, 0);
-	mem_map = contig_page_data.node_mem_map;
 }
 
 /* Initialize remaps of some I/O-ports. It is important that this

arch/ia64/mm/contig.c

@@ -280,7 +280,7 @@ paging_init (void)
 		vmem_map = (struct page *) vmalloc_end;
 		efi_memmap_walk(create_mem_map_page_table, NULL);
 
-		mem_map = contig_page_data.node_mem_map = vmem_map;
+		NODE_DATA(0)->node_mem_map = vmem_map;
 		free_area_init_node(0, &contig_page_data, zones_size,
 				    0, zholes_size);
 

arch/m32r/mm/init.c

@@ -121,8 +121,6 @@ unsigned long __init zone_sizes_init(void)
 
 	free_area_init_node(0, NODE_DATA(0), zones_size, start_pfn, 0);
 
-	mem_map = contig_page_data.node_mem_map;
-
 	return 0;
 }
 #else	/* CONFIG_DISCONTIGMEM */

arch/ppc64/mm/init.c

@@ -666,7 +666,6 @@ void __init paging_init(void)
 
 	free_area_init_node(0, &contig_page_data, zones_size,
 			    __pa(PAGE_OFFSET) >> PAGE_SHIFT, zholes_size);
-	mem_map = contig_page_data.node_mem_map;
 }
 #endif /* CONFIG_DISCONTIGMEM */
 

arch/sh/mm/init.c

@@ -216,8 +216,6 @@ void __init paging_init(void)
 #endif
 	NODE_DATA(0)->node_mem_map = NULL;
 	free_area_init_node(0, NODE_DATA(0), zones_size, __MEMORY_START >> PAGE_SHIFT, 0);
-	/* XXX: MRB-remove - this doesn't seem sane, should this be done somewhere else ?*/
-	mem_map = NODE_DATA(0)->node_mem_map;
 
 #ifdef CONFIG_DISCONTIGMEM
 	/*

arch/sh64/mm/init.c

@@ -124,9 +124,6 @@ void __init paging_init(void)
 	zones_size[ZONE_DMA] = MAX_LOW_PFN - START_PFN;
 	NODE_DATA(0)->node_mem_map = NULL;
 	free_area_init_node(0, NODE_DATA(0), zones_size, __MEMORY_START >> PAGE_SHIFT, 0);
-
-	/* XXX: MRB-remove - this doesn't seem sane, should this be done somewhere else ?*/
-	mem_map = NODE_DATA(0)->node_mem_map;
 }
 
 void __init mem_init(void)

arch/sparc/mm/srmmu.c

@@ -1343,7 +1343,6 @@ void __init srmmu_paging_init(void)
 
 		free_area_init_node(0, &contig_page_data, zones_size,
 				    pfn_base, zholes_size);
-		mem_map = contig_page_data.node_mem_map;
 	}
 }
 

arch/sparc/mm/sun4c.c

@@ -2117,7 +2117,6 @@ void __init sun4c_paging_init(void)
 
 		free_area_init_node(0, &contig_page_data, zones_size,
 				    pfn_base, zholes_size);
-		mem_map = contig_page_data.node_mem_map;
 	}
 
 	cnt = 0;

arch/sparc64/mm/init.c

@@ -1513,7 +1513,6 @@ void __init paging_init(void)
 
 		free_area_init_node(0, &contig_page_data, zones_size,
 				    phys_base >> PAGE_SHIFT, zholes_size);
-		mem_map = contig_page_data.node_mem_map;
 	}
 
 	device_scan();

arch/um/kernel/physmem.c

@@ -294,7 +294,6 @@ int init_maps(unsigned long physmem, unsigned long iomem, unsigned long highmem)
 		INIT_LIST_HEAD(&p->lru);
 	}
 
-	mem_map = map;
 	max_mapnr = total_pages;
 	return(0);
 }

arch/v850/kernel/setup.c

@@ -283,5 +283,4 @@ init_mem_alloc (unsigned long ram_start, unsigned long ram_len)
 	NODE_DATA(0)->node_mem_map = NULL;
 	free_area_init_node (0, NODE_DATA(0), zones_size,
 			     ADDR_TO_PAGE (PAGE_OFFSET), 0);
-	mem_map = NODE_DATA(0)->node_mem_map;
 }

mm/page_alloc.c

@@ -1726,14 +1726,25 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
 	}
 }
 
-void __init node_alloc_mem_map(struct pglist_data *pgdat)
+static void __init alloc_node_mem_map(struct pglist_data *pgdat)
 {
 	unsigned long size;
 
-	size = (pgdat->node_spanned_pages + 1) * sizeof(struct page);
-	pgdat->node_mem_map = alloc_bootmem_node(pgdat, size);
+	/* Skip empty nodes */
+	if (!pgdat->node_spanned_pages)
+		return;
+
+	/* ia64 gets its own node_mem_map, before this, without bootmem */
+	if (!pgdat->node_mem_map) {
+		size = (pgdat->node_spanned_pages + 1) * sizeof(struct page);
+		pgdat->node_mem_map = alloc_bootmem_node(pgdat, size);
+	}
 #ifndef CONFIG_DISCONTIGMEM
-	mem_map = contig_page_data.node_mem_map;
+	/*
+	 * With no DISCONTIG, the global mem_map is just set as node 0's
+	 */
+	if (pgdat == NODE_DATA(0))
+		mem_map = NODE_DATA(0)->node_mem_map;
 #endif
 }
 
@@ -1745,8 +1756,7 @@ void __init free_area_init_node(int nid, struct pglist_data *pgdat,
 	pgdat->node_start_pfn = node_start_pfn;
 	calculate_zone_totalpages(pgdat, zones_size, zholes_size);
 
-	if (!pfn_to_page(node_start_pfn))
-		node_alloc_mem_map(pgdat);
+	alloc_node_mem_map(pgdat);
 
 	free_area_init_core(pgdat, zones_size, zholes_size);
 }