[RHEL6.8 Patch 02/19] asm-generic, mm: pgtable: consolidate zero page helpers

[Baoquan He <bhe@redhat.com>]

Resolves: bz1097904
https://bugzilla.redhat.com/show_bug.cgi?id=1097904

This is back ported from upstream. There are conflicts in
arch/s390/include/asm/pgtable.h.

commit 816422ad76474fed8052b6f7b905a054d082e59a
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Date:   Wed Dec 12 13:52:36 2012 -0800

    asm-generic, mm: pgtable: consolidate zero page helpers

    We have two different implementation of is_zero_pfn() and my_zero_pfn()
    helpers: for architectures with and without zero page coloring.

    Let's consolidate them in <asm-generic/pgtable.h>.

    Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/mips/include/asm/pgtable.h | 10 +---------
 arch/s390/include/asm/pgtable.h | 10 +---------
 include/asm-generic/pgtable.h   | 26 ++++++++++++++++++++++++++
 mm/memory.c                     | 14 --------------
 4 files changed, 28 insertions(+), 32 deletions(-)

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index d6eb613..847edf2 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -76,15 +76,7 @@ extern unsigned long zero_page_mask;
 #define ZERO_PAGE(vaddr) \
 	(virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask))))
 
-#define is_zero_pfn is_zero_pfn
-static inline int is_zero_pfn(unsigned long pfn)
-{
-	extern unsigned long zero_pfn;
-	unsigned long offset_from_zero_pfn = pfn - zero_pfn;
-	return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
-}
-
-#define my_zero_pfn(addr)	page_to_pfn(ZERO_PAGE(addr))
+#define __HAVE_COLOR_ZERO_PAGE
 
 extern void paging_init(void);
 
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index a66fddf..ab7e604 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -57,15 +57,7 @@ extern unsigned long zero_page_mask;
 	(virt_to_page((void *)(empty_zero_page + \
 	 (((unsigned long)(vaddr)) &zero_page_mask))))
 
-#define is_zero_pfn is_zero_pfn
-static inline int is_zero_pfn(unsigned long pfn)
-{
-	extern unsigned long zero_pfn;
-	unsigned long offset_from_zero_pfn = pfn - zero_pfn;
-	return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
-}
-
-#define my_zero_pfn(addr)	page_to_pfn(ZERO_PAGE(addr))
+#define __HAVE_COLOR_ZERO_PAGE
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 5122ec9..78f3f2f 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -471,6 +471,32 @@ extern void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
 				unsigned long size);
 #endif
 
+#ifdef __HAVE_COLOR_ZERO_PAGE
+static inline int is_zero_pfn(unsigned long pfn)
+{
+	extern unsigned long zero_pfn;
+	unsigned long offset_from_zero_pfn = pfn - zero_pfn;
+	return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
+}
+
+static inline unsigned long my_zero_pfn(unsigned long addr)
+{
+	return page_to_pfn(ZERO_PAGE(addr));
+}
+#else
+static inline int is_zero_pfn(unsigned long pfn)
+{
+	extern unsigned long zero_pfn;
+	return pfn == zero_pfn;
+}
+
+static inline unsigned long my_zero_pfn(unsigned long addr)
+{
+	extern unsigned long zero_pfn;
+	return zero_pfn;
+}
+#endif
+
 #ifndef CONFIG_TRANSPARENT_HUGEPAGE
 #define pmd_trans_huge(pmd) 0
 #define pmd_trans_splitting(pmd) (0)
diff --git a/mm/memory.c b/mm/memory.c
index d94cae4..89daff0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -468,20 +468,6 @@ static inline int is_cow_mapping(unsigned int flags)
 	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 }
 
-#ifndef is_zero_pfn
-static inline int is_zero_pfn(unsigned long pfn)
-{
-	return pfn == zero_pfn;
-}
-#endif
-
-#ifndef my_zero_pfn
-static inline unsigned long my_zero_pfn(unsigned long addr)
-{
-	return zero_pfn;
-}
-#endif
-
 /*
  * vm_normal_page -- This function gets the "struct page" associated with a pte.
  *
-- 
2.1.0