mm: meminit: move page initialization into a separate function

Currently, memmap_init_zone() has all the smarts for initializing a single
page.  A subset of this is required for parallel page initialisation and
so this patch breaks up the monolithic function in preparation.

Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -764,6 +764,51 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
 	return 0;
 }
 
+static void __meminit __init_single_page(struct page *page, unsigned long pfn,
+				unsigned long zone, int nid)
+{
+	struct zone *z = &NODE_DATA(nid)->node_zones[zone];
+
+	set_page_links(page, zone, nid, pfn);
+	mminit_verify_page_links(page, zone, nid, pfn);
+	init_page_count(page);
+	page_mapcount_reset(page);
+	page_cpupid_reset_last(page);
+	SetPageReserved(page);
+
+	/*
+	 * Mark the block movable so that blocks are reserved for
+	 * movable at startup. This will force kernel allocations
+	 * to reserve their blocks rather than leaking throughout
+	 * the address space during boot when many long-lived
+	 * kernel allocations are made. Later some blocks near
+	 * the start are marked MIGRATE_RESERVE by
+	 * setup_zone_migrate_reserve()
+	 *
+	 * bitmap is created for zone's valid pfn range. but memmap
+	 * can be created for invalid pages (for alignment)
+	 * check here not to call set_pageblock_migratetype() against
+	 * pfn out of zone.
+	 */
+	if ((z->zone_start_pfn <= pfn)
+	    && (pfn < zone_end_pfn(z))
+	    && !(pfn & (pageblock_nr_pages - 1)))
+		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+
+	INIT_LIST_HEAD(&page->lru);
+#ifdef WANT_PAGE_VIRTUAL
+	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
+	if (!is_highmem_idx(zone))
+		set_page_address(page, __va(pfn << PAGE_SHIFT));
+#endif
+}
+
+static void __meminit __init_single_pfn(unsigned long pfn, unsigned long zone,
+					int nid)
+{
+	return __init_single_page(pfn_to_page(pfn), pfn, zone, nid);
+}
+
 static bool free_pages_prepare(struct page *page, unsigned int order)
 {
 	bool compound = PageCompound(page);
@@ -4212,7 +4257,6 @@ static void setup_zone_migrate_reserve(struct zone *zone)
 void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		unsigned long start_pfn, enum memmap_context context)
 {
-	struct page *page;
 	unsigned long end_pfn = start_pfn + size;
 	unsigned long pfn;
 	struct zone *z;
@@ -4233,38 +4277,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 			if (!early_pfn_in_nid(pfn, nid))
 				continue;
 		}
-		page = pfn_to_page(pfn);
-		set_page_links(page, zone, nid, pfn);
-		mminit_verify_page_links(page, zone, nid, pfn);
-		init_page_count(page);
-		page_mapcount_reset(page);
-		page_cpupid_reset_last(page);
-		SetPageReserved(page);
-		/*
-		 * Mark the block movable so that blocks are reserved for
-		 * movable at startup. This will force kernel allocations
-		 * to reserve their blocks rather than leaking throughout
-		 * the address space during boot when many long-lived
-		 * kernel allocations are made. Later some blocks near
-		 * the start are marked MIGRATE_RESERVE by
-		 * setup_zone_migrate_reserve()
-		 *
-		 * bitmap is created for zone's valid pfn range. but memmap
-		 * can be created for invalid pages (for alignment)
-		 * check here not to call set_pageblock_migratetype() against
-		 * pfn out of zone.
-		 */
-		if ((z->zone_start_pfn <= pfn)
-		    && (pfn < zone_end_pfn(z))
-		    && !(pfn & (pageblock_nr_pages - 1)))
-			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-
-		INIT_LIST_HEAD(&page->lru);
-#ifdef WANT_PAGE_VIRTUAL
-		/* The shift won't overflow because ZONE_NORMAL is below 4G. */
-		if (!is_highmem_idx(zone))
-			set_page_address(page, __va(pfn << PAGE_SHIFT));
-#endif
+		__init_single_pfn(pfn, zone, nid);
 	}
 }