1 files changed, 83 insertions, 15 deletions

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index d25bd224d370..e9fd04ca1e51 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -25,9 +25,19 @@
  * pointing to this anon_vma once its vma list is empty.
  */
 struct anon_vma {
+	struct anon_vma *root;	/* Root of this anon_vma tree */
 	spinlock_t lock;	/* Serialize access to vma list */
-#ifdef CONFIG_KSM
-	atomic_t ksm_refcount;
+#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
+
+	/*
+	 * The external_refcount is taken by either KSM or page migration
+	 * to take a reference to an anon_vma when there is no
+	 * guarantee that the vma of page tables will exist for
+	 * the duration of the operation. A caller that takes
+	 * the reference is responsible for clearing up the
+	 * anon_vma if they are the last user on release
+	 */
+	atomic_t external_refcount;
 #endif
 	/*
 	 * NOTE: the LSB of the head.next is set by
@@ -61,25 +71,40 @@ struct anon_vma_chain {
 };
 
 #ifdef CONFIG_MMU
-#ifdef CONFIG_KSM
-static inline void ksm_refcount_init(struct anon_vma *anon_vma)
+#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
+static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
 {
-	atomic_set(&anon_vma->ksm_refcount, 0);
+	atomic_set(&anon_vma->external_refcount, 0);
 }
 
-static inline int ksm_refcount(struct anon_vma *anon_vma)
+static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
 {
-	return atomic_read(&anon_vma->ksm_refcount);
+	return atomic_read(&anon_vma->external_refcount);
 }
+
+static inline void get_anon_vma(struct anon_vma *anon_vma)
+{
+	atomic_inc(&anon_vma->external_refcount);
+}
+
+void drop_anon_vma(struct anon_vma *);
 #else
-static inline void ksm_refcount_init(struct anon_vma *anon_vma)
+static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
 {
 }
 
-static inline int ksm_refcount(struct anon_vma *anon_vma)
+static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
 {
 	return 0;
 }
+
+static inline void get_anon_vma(struct anon_vma *anon_vma)
+{
+}
+
+static inline void drop_anon_vma(struct anon_vma *anon_vma)
+{
+}
 #endif /* CONFIG_KSM */
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
@@ -90,18 +115,28 @@ static inline struct anon_vma *page_anon_vma(struct page *page)
 	return page_rmapping(page);
 }
 
-static inline void anon_vma_lock(struct vm_area_struct *vma)
+static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
 {
 	struct anon_vma *anon_vma = vma->anon_vma;
 	if (anon_vma)
-		spin_lock(&anon_vma->lock);
+		spin_lock(&anon_vma->root->lock);
 }
 
-static inline void anon_vma_unlock(struct vm_area_struct *vma)
+static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
 {
 	struct anon_vma *anon_vma = vma->anon_vma;
 	if (anon_vma)
-		spin_unlock(&anon_vma->lock);
+		spin_unlock(&anon_vma->root->lock);
+}
+
+static inline void anon_vma_lock(struct anon_vma *anon_vma)
+{
+	spin_lock(&anon_vma->root->lock);
+}
+
+static inline void anon_vma_unlock(struct anon_vma *anon_vma)
+{
+	spin_unlock(&anon_vma->root->lock);
 }
 
 /*
@@ -127,10 +162,17 @@ static inline void anon_vma_merge(struct vm_area_struct *vma,
  */
 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
+void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
+			   unsigned long, int);
 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_file_rmap(struct page *);
 void page_remove_rmap(struct page *);
 
+void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
+			    unsigned long);
+void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
+				unsigned long);
+
 static inline void page_dup_rmap(struct page *page)
 {
 	atomic_inc(&page->_mapcount);
@@ -156,6 +198,8 @@ enum ttu_flags {
 };
 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
 
+bool is_vma_temporary_stack(struct vm_area_struct *vma);
+
 int try_to_unmap(struct page *, enum ttu_flags flags);
 int try_to_unmap_one(struct page *, struct vm_area_struct *,
 			unsigned long address, enum ttu_flags flags);
@@ -163,9 +207,20 @@ int try_to_unmap_one(struct page *, struct vm_area_struct *,
 /*
  * Called from mm/filemap_xip.c to unmap empty zero page
  */
-pte_t *page_check_address(struct page *, struct mm_struct *,
+pte_t *__page_check_address(struct page *, struct mm_struct *,
 				unsigned long, spinlock_t **, int);
 
+static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
+					unsigned long address,
+					spinlock_t **ptlp, int sync)
+{
+	pte_t *ptep;
+
+	__cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
+						       ptlp, sync));
+	return ptep;
+}
+
 /*
  * Used by swapoff to help locate where page is expected in vma.
  */
@@ -188,7 +243,20 @@ int try_to_munlock(struct page *);
 /*
  * Called by memory-failure.c to kill processes.
  */
-struct anon_vma *page_lock_anon_vma(struct page *page);
+struct anon_vma *__page_lock_anon_vma(struct page *page);
+
+static inline struct anon_vma *page_lock_anon_vma(struct page *page)
+{
+	struct anon_vma *anon_vma;
+
+	__cond_lock(RCU, anon_vma = __page_lock_anon_vma(page));
+
+	/* (void) is needed to make gcc happy */
+	(void) __cond_lock(&anon_vma->root->lock, anon_vma);
+
+	return anon_vma;
+}
+
 void page_unlock_anon_vma(struct anon_vma *anon_vma);
 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);