mm: make copy_pte_range static again

Commit 71e3aac0 ("thp: transparent hugepage core") adds
copy_pte_range prototype to huge_mm.h.  I'm not sure why (or if) this
function have been used outside of memory.c, but it currently isn't.
This patch makes copy_pte_range() static again.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/huge_mm.h

@@ -93,10 +93,6 @@ extern bool is_vma_temporary_stack(struct vm_area_struct *vma);
 #endif /* CONFIG_DEBUG_VM */
 
 extern unsigned long transparent_hugepage_flags;
-extern int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-			  pmd_t *dst_pmd, pmd_t *src_pmd,
-			  struct vm_area_struct *vma,
-			  unsigned long addr, unsigned long end);
 extern int split_huge_page_to_list(struct page *page, struct list_head *list);
 static inline int split_huge_page(struct page *page)
 {

mm/memory.c

@@ -884,7 +884,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	return 0;
 }
 
-int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 		   unsigned long addr, unsigned long end)
 {