is_vmalloc_addr(): Check if an address is within the vmalloc boundaries

Checking if an address is a vmalloc address is done in a couple of places.
Define a common version in mm.h and replace the other checks.

Again the include structures suck.  The definition of VMALLOC_START and
VMALLOC_END is not available in vmalloc.h since highmem.c cannot be included
there.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/sparse.c b/mm/sparse.c
index a2183cb..7859c80 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -353,17 +353,9 @@
 	return __kmalloc_section_memmap(nr_pages);
 }
 
-static int vaddr_in_vmalloc_area(void *addr)
-{
-	if (addr >= (void *)VMALLOC_START &&
-	    addr < (void *)VMALLOC_END)
-		return 1;
-	return 0;
-}
-
 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 {
-	if (vaddr_in_vmalloc_area(memmap))
+	if (is_vmalloc_addr(memmap))
 		vfree(memmap);
 	else
 		free_pages((unsigned long)memmap,