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-rw-r--r--arch/i386/Kconfig1
-rw-r--r--include/linux/mm.h92
-rw-r--r--include/linux/mmzone.h96
-rw-r--r--include/linux/numa.h2
-rw-r--r--mm/Kconfig38
-rw-r--r--mm/Makefile1
-rw-r--r--mm/bootmem.c9
-rw-r--r--mm/memory.c2
-rw-r--r--mm/page_alloc.c39
-rw-r--r--mm/sparse.c85
10 files changed, 332 insertions, 33 deletions
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 3b7248126d29..f0064b5e3702 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -813,6 +813,7 @@ source "mm/Kconfig"
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 57b2ead51dba..6eb7f48317f8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -397,40 +397,80 @@ static inline void put_page(struct page *page)
* 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 @@ static inline struct zone *page_zone(struct page *page)
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 @@ static inline void set_page_node(struct page *page, unsigned long node)
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 6ef07de98d69..19860d317ec2 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -269,7 +269,9 @@ typedef struct pglist_data {
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 @@ typedef struct pglist_data {
#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 @@ extern struct pglist_data contig_page_data;
#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 @@ extern struct pglist_data contig_page_data;
#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 bd0c8c4e9a95..f0c539bd3cfc 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 5127441561b4..cd379936cac6 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -6,6 +6,7 @@ choice
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 @@ config FLATMEM_MANUAL
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 @@ config DISCONTIGMEM_MANUAL
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 NEED_MULTIPLE_NODES
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 097408064f6a..8f70ffd763c8 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -15,6 +15,7 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
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 260e703850d8..f82f7aebbee3 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -256,6 +256,7 @@ found:
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 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
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 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
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 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
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 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
}
} 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 da91b7bf9986..30975ef48722 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 20e239599db0..5c1b8982a6da 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -68,7 +68,7 @@ EXPORT_SYMBOL(nr_swap_pages);
* 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 @@ static void __init calculate_zone_totalpages(struct pglist_data *pgdat,
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 @@ void zone_init_free_lists(struct pglist_data *pgdat, struct zone *zone,
}
}
+#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 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
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 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
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 free_area_init_core(struct pglist_data *pgdat,
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 000000000000..f888385b9e14
--- /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);
+ }
+}