mm: meminit: only set page reserved in the memblock region

Currently each page struct is set as reserved upon initialization.  This
patch leaves the reserved bit clear and only sets the reserved bit when it
is known the memory was allocated by the bootmem allocator.  This makes it
easier to distinguish between uninitialised struct pages and reserved
struct pages in later patches.

Signed-off-by: Robin Holt <[email protected]>
Signed-off-by: Nathan Zimmer <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Tested-by: Nate Zimmer <[email protected]>
Tested-by: Waiman Long <[email protected]>
Tested-by: Daniel J Blueman <[email protected]>
Acked-by: Pekka Enberg <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Scott Norton <[email protected]>
Cc: "Luck, Tony" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bc5da2c..39c8d56 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -774,7 +774,6 @@
 	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
@@ -809,6 +808,22 @@
 	return __init_single_page(pfn_to_page(pfn), pfn, zone, nid);
 }
 
+/*
+ * Initialised pages do not have PageReserved set. This function is
+ * called for each range allocated by the bootmem allocator and
+ * marks the pages PageReserved. The remaining valid pages are later
+ * sent to the buddy page allocator.
+ */
+void reserve_bootmem_region(unsigned long start, unsigned long end)
+{
+	unsigned long start_pfn = PFN_DOWN(start);
+	unsigned long end_pfn = PFN_UP(end);
+
+	for (; start_pfn < end_pfn; start_pfn++)
+		if (pfn_valid(start_pfn))
+			SetPageReserved(pfn_to_page(start_pfn));
+}
+
 static bool free_pages_prepare(struct page *page, unsigned int order)
 {
 	bool compound = PageCompound(page);