[PATCH 1/2] NOMMU: There is no mlock() for NOMMU,so don't provide the bits

[David Howells]

The mlock() facility does not exist for NOMMU since all mappings are
effectively locked anyway, so we don't make the bits available when they're
not useful.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 include/linux/page-flags.h |   20 +++++++++++++-------
 mm/Kconfig                 |    8 ++++++++
 mm/internal.h              |    8 +++++---
 3 files changed, 26 insertions(+), 10 deletions(-)


diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 219a523..61df177 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -96,6 +96,8 @@ enum pageflags {
 	PG_swapbacked,		/* Page is backed by RAM/swap */
 #ifdef CONFIG_UNEVICTABLE_LRU
 	PG_unevictable,		/* Page is "unevictable"  */
+#endif
+#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
 	PG_mlocked,		/* Page is vma mlocked */
 #endif
 #ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
@@ -234,20 +236,20 @@ PAGEFLAG_FALSE(SwapCache)
 #ifdef CONFIG_UNEVICTABLE_LRU
 PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
 	TESTCLEARFLAG(Unevictable, unevictable)
+#else
+PAGEFLAG_FALSE(Unevictable) TESTCLEARFLAG_FALSE(Unevictable)
+	SETPAGEFLAG_NOOP(Unevictable) CLEARPAGEFLAG_NOOP(Unevictable)
+	__CLEARPAGEFLAG_NOOP(Unevictable)
+#endif
 
+#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
 #define MLOCK_PAGES 1
 PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
 	TESTSCFLAG(Mlocked, mlocked)
-
 #else
-
 #define MLOCK_PAGES 0
 PAGEFLAG_FALSE(Mlocked)
 	SETPAGEFLAG_NOOP(Mlocked) TESTCLEARFLAG_FALSE(Mlocked)
-
-PAGEFLAG_FALSE(Unevictable) TESTCLEARFLAG_FALSE(Unevictable)
-	SETPAGEFLAG_NOOP(Unevictable) CLEARPAGEFLAG_NOOP(Unevictable)
-	__CLEARPAGEFLAG_NOOP(Unevictable)
 #endif
 
 #ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
@@ -367,9 +369,13 @@ static inline void __ClearPageTail(struct page *page)
 
 #ifdef CONFIG_UNEVICTABLE_LRU
 #define __PG_UNEVICTABLE	(1 << PG_unevictable)
-#define __PG_MLOCKED		(1 << PG_mlocked)
 #else
 #define __PG_UNEVICTABLE	0
+#endif
+
+#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
+#define __PG_MLOCKED		(1 << PG_mlocked)
+#else
 #define __PG_MLOCKED		0
 #endif
 
diff --git a/mm/Kconfig b/mm/Kconfig
index a5b7781..8c89597 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -214,5 +214,13 @@ config UNEVICTABLE_LRU
 	  will use one page flag and increase the code size a little,
 	  say Y unless you know what you are doing.
 
+config HAVE_MLOCK
+	bool
+	default y if MMU=y
+
+config HAVE_MLOCKED_PAGE_BIT
+	bool
+	default y if HAVE_MLOCK=y && UNEVICTABLE_LRU=y
+
 config MMU_NOTIFIER
 	bool
diff --git a/mm/internal.h b/mm/internal.h
index 478223b..987bb03 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -63,6 +63,7 @@ static inline unsigned long page_order(struct page *page)
 	return page_private(page);
 }
 
+#ifdef CONFIG_HAVE_MLOCK
 extern long mlock_vma_pages_range(struct vm_area_struct *vma,
 			unsigned long start, unsigned long end);
 extern void munlock_vma_pages_range(struct vm_area_struct *vma,
@@ -71,6 +72,7 @@ static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
 {
 	munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
 }
+#endif
 
 #ifdef CONFIG_UNEVICTABLE_LRU
 /*
@@ -90,7 +92,7 @@ static inline void unevictable_migrate_page(struct page *new, struct page *old)
 }
 #endif
 
-#ifdef CONFIG_UNEVICTABLE_LRU
+#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
 /*
  * Called only in fault path via page_evictable() for a new page
  * to determine if it's being mapped into a LOCKED vma.
@@ -165,7 +167,7 @@ static inline void free_page_mlock(struct page *page)
 	}
 }
 
-#else /* CONFIG_UNEVICTABLE_LRU */
+#else /* CONFIG_HAVE_MLOCKED_PAGE_BIT */
 static inline int is_mlocked_vma(struct vm_area_struct *v, struct page *p)
 {
 	return 0;
@@ -175,7 +177,7 @@ static inline void mlock_vma_page(struct page *page) { }
 static inline void mlock_migrate_page(struct page *new, struct page *old) { }
 static inline void free_page_mlock(struct page *page) { }
 
-#endif /* CONFIG_UNEVICTABLE_LRU */
+#endif /* CONFIG_HAVE_MLOCKED_PAGE_BIT */
 
 /*
  * Return the mem_map entry representing the 'offset' subpage within

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