diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 3b72481..f0064b5 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -813,6 +813,7 @@
 config HAVE_ARCH_EARLY_PFN_TO_NID
 	bool
 	default y
+	depends on NUMA
 
 config HIGHPTE
 	bool "Allocate 3rd-level pagetables from highmem"
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 57b2ead..6eb7f48 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -397,40 +397,80 @@
  * sets it, so none of the operations on it need to be atomic.
  */
 
-/* Page flags: | NODE | ZONE | ... | FLAGS | */
-#define NODES_PGOFF		((sizeof(page_flags_t)*8) - NODES_SHIFT)
-#define ZONES_PGOFF		(NODES_PGOFF - ZONES_SHIFT)
+
+/*
+ * page->flags layout:
+ *
+ * There are three possibilities for how page->flags get
+ * laid out.  The first is for the normal case, without
+ * sparsemem.  The second is for sparsemem when there is
+ * plenty of space for node and section.  The last is when
+ * we have run out of space and have to fall back to an
+ * alternate (slower) way of determining the node.
+ *
+ *        No sparsemem: |       NODE     | ZONE | ... | FLAGS |
+ * with space for node: | SECTION | NODE | ZONE | ... | FLAGS |
+ *   no space for node: | SECTION |     ZONE    | ... | FLAGS |
+ */
+#ifdef CONFIG_SPARSEMEM
+#define SECTIONS_WIDTH		SECTIONS_SHIFT
+#else
+#define SECTIONS_WIDTH		0
+#endif
+
+#define ZONES_WIDTH		ZONES_SHIFT
+
+#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= FLAGS_RESERVED
+#define NODES_WIDTH		NODES_SHIFT
+#else
+#define NODES_WIDTH		0
+#endif
+
+/* Page flags: | [SECTION] | [NODE] | ZONE | ... | FLAGS | */
+#define SECTIONS_PGOFF		((sizeof(page_flags_t)*8) - SECTIONS_WIDTH)
+#define NODES_PGOFF		(SECTIONS_PGOFF - NODES_WIDTH)
+#define ZONES_PGOFF		(NODES_PGOFF - ZONES_WIDTH)
+
+/*
+ * We are going to use the flags for the page to node mapping if its in
+ * there.  This includes the case where there is no node, so it is implicit.
+ */
+#define FLAGS_HAS_NODE		(NODES_WIDTH > 0 || NODES_SHIFT == 0)
+
+#ifndef PFN_SECTION_SHIFT
+#define PFN_SECTION_SHIFT 0
+#endif
 
 /*
  * Define the bit shifts to access each section.  For non-existant
  * sections we define the shift as 0; that plus a 0 mask ensures
  * the compiler will optimise away reference to them.
  */
-#define NODES_PGSHIFT		(NODES_PGOFF * (NODES_SHIFT != 0))
-#define ZONES_PGSHIFT		(ZONES_PGOFF * (ZONES_SHIFT != 0))
+#define SECTIONS_PGSHIFT	(SECTIONS_PGOFF * (SECTIONS_WIDTH != 0))
+#define NODES_PGSHIFT		(NODES_PGOFF * (NODES_WIDTH != 0))
+#define ZONES_PGSHIFT		(ZONES_PGOFF * (ZONES_WIDTH != 0))
 
-/* NODE:ZONE is used to lookup the zone from a page. */
+/* NODE:ZONE or SECTION:ZONE is used to lookup the zone from a page. */
+#if FLAGS_HAS_NODE
 #define ZONETABLE_SHIFT		(NODES_SHIFT + ZONES_SHIFT)
+#else
+#define ZONETABLE_SHIFT		(SECTIONS_SHIFT + ZONES_SHIFT)
+#endif
 #define ZONETABLE_PGSHIFT	ZONES_PGSHIFT
 
-#if NODES_SHIFT+ZONES_SHIFT > FLAGS_RESERVED
-#error NODES_SHIFT+ZONES_SHIFT > FLAGS_RESERVED
+#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > FLAGS_RESERVED
+#error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > FLAGS_RESERVED
 #endif
 
-#define NODEZONE(node, zone)	((node << ZONES_SHIFT) | zone)
-
-#define ZONES_MASK		((1UL << ZONES_SHIFT) - 1)
-#define NODES_MASK		((1UL << NODES_SHIFT) - 1)
+#define ZONES_MASK		((1UL << ZONES_WIDTH) - 1)
+#define NODES_MASK		((1UL << NODES_WIDTH) - 1)
+#define SECTIONS_MASK		((1UL << SECTIONS_WIDTH) - 1)
 #define ZONETABLE_MASK		((1UL << ZONETABLE_SHIFT) - 1)
 
 static inline unsigned long page_zonenum(struct page *page)
 {
 	return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
 }
-static inline unsigned long page_to_nid(struct page *page)
-{
-	return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
-}
 
 struct zone;
 extern struct zone *zone_table[];
@@ -441,6 +481,18 @@
 			ZONETABLE_MASK];
 }
 
+static inline unsigned long page_to_nid(struct page *page)
+{
+	if (FLAGS_HAS_NODE)
+		return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
+	else
+		return page_zone(page)->zone_pgdat->node_id;
+}
+static inline unsigned long page_to_section(struct page *page)
+{
+	return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
+}
+
 static inline void set_page_zone(struct page *page, unsigned long zone)
 {
 	page->flags &= ~(ZONES_MASK << ZONES_PGSHIFT);
@@ -451,12 +503,18 @@
 	page->flags &= ~(NODES_MASK << NODES_PGSHIFT);
 	page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;
 }
+static inline void set_page_section(struct page *page, unsigned long section)
+{
+	page->flags &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
+	page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
+}
 
 static inline void set_page_links(struct page *page, unsigned long zone,
-	unsigned long node)
+	unsigned long node, unsigned long pfn)
 {
 	set_page_zone(page, zone);
 	set_page_node(page, node);
+	set_page_section(page, pfn_to_section_nr(pfn));
 }
 
 #ifndef CONFIG_DISCONTIGMEM
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6ef07de..19860d3 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -269,7 +269,9 @@
 	struct zone node_zones[MAX_NR_ZONES];
 	struct zonelist node_zonelists[GFP_ZONETYPES];
 	int nr_zones;
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
 	struct page *node_mem_map;
+#endif
 	struct bootmem_data *bdata;
 	unsigned long node_start_pfn;
 	unsigned long node_present_pages; /* total number of physical pages */
@@ -284,7 +286,11 @@
 
 #define node_present_pages(nid)	(NODE_DATA(nid)->node_present_pages)
 #define node_spanned_pages(nid)	(NODE_DATA(nid)->node_spanned_pages)
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
 #define pgdat_page_nr(pgdat, pagenr)	((pgdat)->node_mem_map + (pagenr))
+#else
+#define pgdat_page_nr(pgdat, pagenr)	pfn_to_page((pgdat)->node_start_pfn + (pagenr))
+#endif
 #define nid_page_nr(nid, pagenr) 	pgdat_page_nr(NODE_DATA(nid),(pagenr))
 
 extern struct pglist_data *pgdat_list;
@@ -416,6 +422,10 @@
 
 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
 
+#ifdef CONFIG_SPARSEMEM
+#include <asm/sparsemem.h>
+#endif
+
 #if BITS_PER_LONG == 32 || defined(ARCH_HAS_ATOMIC_UNSIGNED)
 /*
  * with 32 bit page->flags field, we reserve 8 bits for node/zone info.
@@ -439,6 +449,92 @@
 #define early_pfn_to_nid(nid)  (0UL)
 #endif
 
+#define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
+#define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
+
+#ifdef CONFIG_SPARSEMEM
+
+/*
+ * SECTION_SHIFT    		#bits space required to store a section #
+ *
+ * PA_SECTION_SHIFT		physical address to/from section number
+ * PFN_SECTION_SHIFT		pfn to/from section number
+ */
+#define SECTIONS_SHIFT		(MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
+
+#define PA_SECTION_SHIFT	(SECTION_SIZE_BITS)
+#define PFN_SECTION_SHIFT	(SECTION_SIZE_BITS - PAGE_SHIFT)
+
+#define NR_MEM_SECTIONS		(1UL << SECTIONS_SHIFT)
+
+#define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
+#define PAGE_SECTION_MASK	(~(PAGES_PER_SECTION-1))
+
+#if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
+#error Allocator MAX_ORDER exceeds SECTION_SIZE
+#endif
+
+struct page;
+struct mem_section {
+	struct page *section_mem_map;
+};
+
+extern struct mem_section mem_section[NR_MEM_SECTIONS];
+
+/*
+ * Given a kernel address, find the home node of the underlying memory.
+ */
+#define kvaddr_to_nid(kaddr)	pfn_to_nid(__pa(kaddr) >> PAGE_SHIFT)
+
+static inline struct mem_section *__pfn_to_section(unsigned long pfn)
+{
+	return &mem_section[pfn_to_section_nr(pfn)];
+}
+
+#define pfn_to_page(pfn) 						\
+({ 									\
+	unsigned long __pfn = (pfn);					\
+	__pfn_to_section(__pfn)->section_mem_map + __pfn;		\
+})
+#define page_to_pfn(page)						\
+({									\
+	page - mem_section[page_to_section(page)].section_mem_map;	\
+})
+
+static inline int pfn_valid(unsigned long pfn)
+{
+	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+		return 0;
+	return mem_section[pfn_to_section_nr(pfn)].section_mem_map != 0;
+}
+
+/*
+ * These are _only_ used during initialisation, therefore they
+ * can use __initdata ...  They could have names to indicate
+ * this restriction.
+ */
+#ifdef CONFIG_NUMA
+#define pfn_to_nid		early_pfn_to_nid
+#endif
+
+#define pfn_to_pgdat(pfn)						\
+({									\
+	NODE_DATA(pfn_to_nid(pfn));					\
+})
+
+#define early_pfn_valid(pfn)	pfn_valid(pfn)
+void sparse_init(void);
+#else
+#define sparse_init()	do {} while (0)
+#endif /* CONFIG_SPARSEMEM */
+
+#ifndef early_pfn_valid
+#define early_pfn_valid(pfn)	(1)
+#endif
+
+void memory_present(int nid, unsigned long start, unsigned long end);
+unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
+
 #endif /* !__ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MMZONE_H */
diff --git a/include/linux/numa.h b/include/linux/numa.h
index bd0c8c4..f0c539b 100644
--- a/include/linux/numa.h
+++ b/include/linux/numa.h
@@ -3,7 +3,7 @@
 
 #include <linux/config.h>
 
-#ifdef CONFIG_DISCONTIGMEM
+#ifndef CONFIG_FLATMEM
 #include <asm/numnodes.h>
 #endif
 
diff --git a/mm/Kconfig b/mm/Kconfig
index 5127441..cd37993 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -6,6 +6,7 @@
 	prompt "Memory model"
 	depends on SELECT_MEMORY_MODEL
 	default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
+	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
 	default FLATMEM_MANUAL
 
 config FLATMEM_MANUAL
@@ -17,7 +18,15 @@
 	  only have one option here: FLATMEM.  This is normal
 	  and a correct option.
 
-	  If unsure, choose this option over any other.
+	  Some users of more advanced features like NUMA and
+	  memory hotplug may have different options here.
+	  DISCONTIGMEM is an more mature, better tested system,
+	  but is incompatible with memory hotplug and may suffer
+	  decreased performance over SPARSEMEM.  If unsure between
+	  "Sparse Memory" and "Discontiguous Memory", choose
+	  "Discontiguous Memory".
+
+	  If unsure, choose this option (Flat Memory) over any other.
 
 config DISCONTIGMEM_MANUAL
 	bool "Discontigious Memory"
@@ -35,15 +44,38 @@
 
 	  If unsure, choose "Flat Memory" over this option.
 
+config SPARSEMEM_MANUAL
+	bool "Sparse Memory"
+	depends on ARCH_SPARSEMEM_ENABLE
+	help
+	  This will be the only option for some systems, including
+	  memory hotplug systems.  This is normal.
+
+	  For many other systems, this will be an alternative to
+	  "Discontigious Memory".  This option provides some potential
+	  performance benefits, along with decreased code complexity,
+	  but it is newer, and more experimental.
+
+	  If unsure, choose "Discontiguous Memory" or "Flat Memory"
+	  over this option.
+
 endchoice
 
 config DISCONTIGMEM
 	def_bool y
 	depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
 
+config SPARSEMEM
+	def_bool y
+	depends on SPARSEMEM_MANUAL
+
 config FLATMEM
 	def_bool y
-	depends on !DISCONTIGMEM || FLATMEM_MANUAL
+	depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
+
+config FLAT_NODE_MEM_MAP
+	def_bool y
+	depends on !SPARSEMEM
 
 #
 # Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
@@ -56,4 +88,4 @@
 
 config HAVE_MEMORY_PRESENT
 	def_bool y
-	depends on ARCH_HAVE_MEMORY_PRESENT
+	depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
diff --git a/mm/Makefile b/mm/Makefile
index 0974080..8f70ffd 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -15,6 +15,7 @@
 obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
 obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
+obj-$(CONFIG_SPARSEMEM)	+= sparse.o
 obj-$(CONFIG_SHMEM) += shmem.o
 obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
 
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 260e703..f82f7ae 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -256,6 +256,7 @@
 static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
 {
 	struct page *page;
+	unsigned long pfn;
 	bootmem_data_t *bdata = pgdat->bdata;
 	unsigned long i, count, total = 0;
 	unsigned long idx;
@@ -266,7 +267,7 @@
 
 	count = 0;
 	/* first extant page of the node */
-	page = virt_to_page(phys_to_virt(bdata->node_boot_start));
+	pfn = bdata->node_boot_start >> PAGE_SHIFT;
 	idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
 	map = bdata->node_bootmem_map;
 	/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
@@ -275,9 +276,11 @@
 		gofast = 1;
 	for (i = 0; i < idx; ) {
 		unsigned long v = ~map[i / BITS_PER_LONG];
+
 		if (gofast && v == ~0UL) {
 			int j, order;
 
+			page = pfn_to_page(pfn);
 			count += BITS_PER_LONG;
 			__ClearPageReserved(page);
 			order = ffs(BITS_PER_LONG) - 1;
@@ -292,6 +295,8 @@
 			page += BITS_PER_LONG;
 		} else if (v) {
 			unsigned long m;
+
+			page = pfn_to_page(pfn);
 			for (m = 1; m && i < idx; m<<=1, page++, i++) {
 				if (v & m) {
 					count++;
@@ -302,8 +307,8 @@
 			}
 		} else {
 			i+=BITS_PER_LONG;
-			page += BITS_PER_LONG;
 		}
+		pfn += BITS_PER_LONG;
 	}
 	total += count;
 
diff --git a/mm/memory.c b/mm/memory.c
index da91b7b..30975ef 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -58,7 +58,7 @@
 #include <linux/swapops.h>
 #include <linux/elf.h>
 
-#ifndef CONFIG_DISCONTIGMEM
+#ifndef CONFIG_NEED_MULTIPLE_NODES
 /* use the per-pgdat data instead for discontigmem - mbligh */
 unsigned long max_mapnr;
 struct page *mem_map;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 20e2395..5c1b898 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -68,7 +68,7 @@
  * Used by page_zone() to look up the address of the struct zone whose
  * id is encoded in the upper bits of page->flags
  */
-struct zone *zone_table[1 << (ZONES_SHIFT + NODES_SHIFT)];
+struct zone *zone_table[1 << ZONETABLE_SHIFT];
 EXPORT_SYMBOL(zone_table);
 
 static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" };
@@ -1649,11 +1649,15 @@
 void __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		unsigned long start_pfn)
 {
-	struct page *start = pfn_to_page(start_pfn);
 	struct page *page;
+	int end_pfn = start_pfn + size;
+	int pfn;
 
-	for (page = start; page < (start + size); page++) {
-		set_page_links(page, zone, nid);
+	for (pfn = start_pfn; pfn < end_pfn; pfn++, page++) {
+		if (!early_pfn_valid(pfn))
+			continue;
+		page = pfn_to_page(pfn);
+		set_page_links(page, zone, nid, pfn);
 		set_page_count(page, 0);
 		reset_page_mapcount(page);
 		SetPageReserved(page);
@@ -1677,6 +1681,20 @@
 	}
 }
 
+#define ZONETABLE_INDEX(x, zone_nr)	((x << ZONES_SHIFT) | zone_nr)
+void zonetable_add(struct zone *zone, int nid, int zid, unsigned long pfn,
+		unsigned long size)
+{
+	unsigned long snum = pfn_to_section_nr(pfn);
+	unsigned long end = pfn_to_section_nr(pfn + size);
+
+	if (FLAGS_HAS_NODE)
+		zone_table[ZONETABLE_INDEX(nid, zid)] = zone;
+	else
+		for (; snum <= end; snum++)
+			zone_table[ZONETABLE_INDEX(snum, zid)] = zone;
+}
+
 #ifndef __HAVE_ARCH_MEMMAP_INIT
 #define memmap_init(size, nid, zone, start_pfn) \
 	memmap_init_zone((size), (nid), (zone), (start_pfn))
@@ -1861,7 +1879,6 @@
 		unsigned long size, realsize;
 		unsigned long batch;
 
-		zone_table[NODEZONE(nid, j)] = zone;
 		realsize = size = zones_size[j];
 		if (zholes_size)
 			realsize -= zholes_size[j];
@@ -1927,6 +1944,8 @@
 
 		memmap_init(size, nid, j, zone_start_pfn);
 
+		zonetable_add(zone, nid, j, zone_start_pfn, size);
+
 		zone_start_pfn += size;
 
 		zone_init_free_lists(pgdat, zone, zone->spanned_pages);
@@ -1935,28 +1954,30 @@
 
 static void __init alloc_node_mem_map(struct pglist_data *pgdat)
 {
-	unsigned long size;
-	struct page *map;
-
 	/* Skip empty nodes */
 	if (!pgdat->node_spanned_pages)
 		return;
 
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
 	/* ia64 gets its own node_mem_map, before this, without bootmem */
 	if (!pgdat->node_mem_map) {
+		unsigned long size;
+		struct page *map;
+
 		size = (pgdat->node_spanned_pages + 1) * sizeof(struct page);
 		map = alloc_remap(pgdat->node_id, size);
 		if (!map)
 			map = alloc_bootmem_node(pgdat, size);
 		pgdat->node_mem_map = map;
 	}
-#ifndef CONFIG_DISCONTIGMEM
+#ifdef CONFIG_FLATMEM
 	/*
 	 * 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
+#endif /* CONFIG_FLAT_NODE_MEM_MAP */
 }
 
 void __init free_area_init_node(int nid, struct pglist_data *pgdat,
diff --git a/mm/sparse.c b/mm/sparse.c
new file mode 100644
index 0000000..f888385
--- /dev/null
+++ b/mm/sparse.c
@@ -0,0 +1,85 @@
+/*
+ * sparse memory mappings.
+ */
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/module.h>
+#include <asm/dma.h>
+
+/*
+ * Permanent SPARSEMEM data:
+ *
+ * 1) mem_section	- memory sections, mem_map's for valid memory
+ */
+struct mem_section mem_section[NR_MEM_SECTIONS];
+EXPORT_SYMBOL(mem_section);
+
+/* Record a memory area against a node. */
+void memory_present(int nid, unsigned long start, unsigned long end)
+{
+	unsigned long pfn;
+
+	start &= PAGE_SECTION_MASK;
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
+		unsigned long section = pfn_to_section_nr(pfn);
+		if (!mem_section[section].section_mem_map)
+			mem_section[section].section_mem_map = (void *) -1;
+	}
+}
+
+/*
+ * Only used by the i386 NUMA architecures, but relatively
+ * generic code.
+ */
+unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
+						     unsigned long end_pfn)
+{
+	unsigned long pfn;
+	unsigned long nr_pages = 0;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		if (nid != early_pfn_to_nid(pfn))
+			continue;
+
+		if (pfn_valid(pfn))
+			nr_pages += PAGES_PER_SECTION;
+	}
+
+	return nr_pages * sizeof(struct page);
+}
+
+/*
+ * Allocate the accumulated non-linear sections, allocate a mem_map
+ * for each and record the physical to section mapping.
+ */
+void sparse_init(void)
+{
+	unsigned long pnum;
+	struct page *map;
+	int nid;
+
+	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
+		if (!mem_section[pnum].section_mem_map)
+			continue;
+
+		nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
+		map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
+		if (!map)
+			map = alloc_bootmem_node(NODE_DATA(nid),
+				sizeof(struct page) * PAGES_PER_SECTION);
+		if (!map) {
+			mem_section[pnum].section_mem_map = 0;
+			continue;
+		}
+
+		/*
+		 * Subtle, we encode the real pfn into the mem_map such that
+		 * the identity pfn - section_mem_map will return the actual
+		 * physical page frame number.
+		 */
+		mem_section[pnum].section_mem_map = map -
+						section_nr_to_pfn(pnum);
+	}
+}