mm/sparse: use page_private() to get page->private value

free_map_bootmem() uses page->private directly to set
removing_section_nr argument.  But to get page->private value,
page_private() has been prepared.

So free_map_bootmem() should use page_private() instead of
page->private.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Yasuaki Ishimatsu <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Xishi Qiu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/sparse.c

@@ -667,7 +667,7 @@ static void free_map_bootmem(struct page *memmap)
 		BUG_ON(magic == NODE_INFO);
 
 		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
-		removing_section_nr = page->private;
+		removing_section_nr = page_private(page);
 
 		/*
 		 * When this function is called, the removing section is