thp: share get_huge_page_tail()

This avoids duplicating the function in every arch gup_fast.

Signed-off-by: Andrea Arcangeli <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: David Gibson <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: David Miller <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

5 files changed, 11 insertions, 44 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 1c59d94f5942..da5eb3885702 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -385,17 +385,6 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 	return NULL;
 }
 
-static inline void get_huge_page_tail(struct page *page)
-{
-	/*
-	 * __split_huge_page_refcount() cannot run
-	 * from under us.
-	 */
-	VM_BUG_ON(page_mapcount(page) < 0);
-	VM_BUG_ON(atomic_read(&page->_count) != 0);
-	atomic_inc(&page->_mapcount);
-}
-
 static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		       unsigned long end, int write, struct page **pages, int *nr)
 {
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index da33a0281d9d..65cb06e2af4e 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -48,17 +48,6 @@ static inline int gup_pte_range(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
 	return 1;
 }
 
-static inline void get_huge_page_tail(struct page *page)
-{
-	/*
-	 * __split_huge_page_refcount() cannot run
-	 * from under us.
-	 */
-	VM_BUG_ON(page_mapcount(page) < 0);
-	VM_BUG_ON(atomic_read(&page->_count) != 0);
-	atomic_inc(&page->_mapcount);
-}
-
 static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
 		unsigned long end, int write, struct page **pages, int *nr)
 {
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index afcebac144fb..42c55df3aec3 100644
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -12,17 +12,6 @@
 #include <linux/rwsem.h>
 #include <asm/pgtable.h>
 
-static inline void get_huge_page_tail(struct page *page)
-{
-	/*
-	 * __split_huge_page_refcount() cannot run
-	 * from under us.
-	 */
-	VM_BUG_ON(page_mapcount(page) < 0);
-	VM_BUG_ON(atomic_read(&page->_count) != 0);
-	atomic_inc(&page->_mapcount);
-}
-
 /*
  * The performance critical leaf functions are made noinline otherwise gcc
  * inlines everything into a single function which results in too much
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 3b5032a62b0f..ea305856151c 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -108,17 +108,6 @@ static inline void get_head_page_multiple(struct page *page, int nr)
 	SetPageReferenced(page);
 }
 
-static inline void get_huge_page_tail(struct page *page)
-{
-	/*
-	 * __split_huge_page_refcount() cannot run
-	 * from under us.
-	 */
-	VM_BUG_ON(page_mapcount(page) < 0);
-	VM_BUG_ON(atomic_read(&page->_count) != 0);
-	atomic_inc(&page->_mapcount);
-}
-
 static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
 		unsigned long end, int write, struct page **pages, int *nr)
 {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f81b7b41930c..3dc3a8c2c485 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -376,6 +376,17 @@ static inline int page_count(struct page *page)
 	return atomic_read(&compound_head(page)->_count);
 }
 
+static inline void get_huge_page_tail(struct page *page)
+{
+	/*
+	 * __split_huge_page_refcount() cannot run
+	 * from under us.
+	 */
+	VM_BUG_ON(page_mapcount(page) < 0);
+	VM_BUG_ON(atomic_read(&page->_count) != 0);
+	atomic_inc(&page->_mapcount);
+}
+
 extern bool __get_page_tail(struct page *page);
 
 static inline void get_page(struct page *page)