[PATCH] remove zone_mem_map

This patch removes zone_mem_map.

pfn_to_page uses pgdat, page_to_pfn uses zone.  page_to_pfn can use pgdat
instead of zone, which is only one user of zone_mem_map.  By modifing it,
we can remove zone_mem_map.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 8 insertions, 12 deletions

diff --git a/include/asm-alpha/mmzone.h b/include/asm-alpha/mmzone.h
index c9004398f273..192d80c875b0 100644
--- a/include/asm-alpha/mmzone.h
+++ b/include/asm-alpha/mmzone.h
@@ -83,8 +83,7 @@ PLAT_NODE_DATA_LOCALNR(unsigned long p, int n)
         pte_t pte;                                                           \
         unsigned long pfn;                                                   \
                                                                              \
-        pfn = ((unsigned long)((page)-page_zone(page)->zone_mem_map)) << 32; \
-        pfn += page_zone(page)->zone_start_pfn << 32;                        \
+        pfn = page_to_pfn(page) << 32; \
         pte_val(pte) = pfn | pgprot_val(pgprot);                             \
                                                                              \
         pte;                                                                 \
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index a7bb4978e808..0cfb086dd373 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -45,11 +45,11 @@ extern unsigned long page_to_pfn(struct page *page);
         NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
 })
 
-#define page_to_pfn(pg)                 \
-({      struct page *__pg = (pg);               \
-        struct zone *__zone = page_zone(__pg);  \
-        (unsigned long)(__pg - __zone->zone_mem_map) +  \
-         __zone->zone_start_pfn;                        \
+#define page_to_pfn(pg)                                                 \
+({      struct page *__pg = (pg);                                       \
+        struct pglist_data *__pgdat = NODE_DATA(page_to_nid(__pg));     \
+        (unsigned long)(__pg - __pgdat->node_mem_map) +                 \
+         __pgdat->node_start_pfn;                                       \
 })
 
 #elif defined(CONFIG_SPARSEMEM)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0c1c0c0cce65..ace31c515a8c 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -225,7 +225,6 @@ struct zone {
          * Discontig memory support fields.
          */
         struct pglist_data      *zone_pgdat;
-        struct page             *zone_mem_map;
         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
         unsigned long           zone_start_pfn;
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 349b328763b7..8dc8f2735d22 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2042,7 +2042,6 @@ static __meminit void init_currently_empty_zone(struct zone *zone,
         zone_wait_table_init(zone, size);
         pgdat->nr_zones = zone_idx(zone) + 1;
 
-        zone->zone_mem_map = pfn_to_page(zone_start_pfn);
         zone->zone_start_pfn = zone_start_pfn;
 
         memmap_init(size, pgdat->node_id, zone_idx(zone), zone_start_pfn);
@@ -2768,9 +2767,8 @@ struct page *pfn_to_page(unsigned long pfn)
 }
 unsigned long page_to_pfn(struct page *page)
 {
-        struct zone *zone = page_zone(page);
-        return (page - zone->zone_mem_map) + zone->zone_start_pfn;
-
+        struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
+        return (page - pgdat->node_mem_map) + pgdat->node_start_pfn;
 }
 #elif defined(CONFIG_SPARSEMEM)
 struct page *pfn_to_page(unsigned long pfn)