diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index d1406037c2bb..7dee138fbf0f 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -43,15 +43,12 @@ struct anon_vma {
 	atomic_t refcount;
 
 	/*
-	 * Count of child anon_vmas. Equals to the count of all anon_vmas that
-	 * have ->parent pointing to this one, including itself.
+	 * Count of child anon_vmas and VMAs which points to this anon_vma.
 	 *
 	 * This counter is used for making decision about reusing anon_vma
 	 * instead of forking new one. See comments in function anon_vma_clone.
 	 */
-	unsigned long num_children;
-	/* Count of VMAs whose ->anon_vma pointer points to this object. */
-	unsigned long num_active_vmas;
+	unsigned degree;
 
 	struct anon_vma *parent;	/* Parent of this anon_vma */
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 69e5cdfb2bd9..2e62c1aa5139 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -91,8 +91,7 @@ static inline struct anon_vma *anon_vma_alloc(void)
 	anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
 	if (anon_vma) {
 		atomic_set(&anon_vma->refcount, 1);
-		anon_vma->num_children = 0;
-		anon_vma->num_active_vmas = 0;
+		anon_vma->degree = 1;	/* Reference for first vma */
 		anon_vma->parent = anon_vma;
 		/*
 		 * Initialise the anon_vma root to point to itself. If called
@@ -200,7 +199,6 @@ int __anon_vma_prepare(struct vm_area_struct *vma)
 		anon_vma = anon_vma_alloc();
 		if (unlikely(!anon_vma))
 			goto out_enomem_free_avc;
-		anon_vma->num_children++; /* self-parent link for new root */
 		allocated = anon_vma;
 	}
 
@@ -210,7 +208,8 @@ int __anon_vma_prepare(struct vm_area_struct *vma)
 	if (likely(!vma->anon_vma)) {
 		vma->anon_vma = anon_vma;
 		anon_vma_chain_link(vma, avc, anon_vma);
-		anon_vma->num_active_vmas++;
+		/* vma reference or self-parent link for new root */
+		anon_vma->degree++;
 		allocated = NULL;
 		avc = NULL;
 	}
@@ -295,19 +294,19 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
 		anon_vma_chain_link(dst, avc, anon_vma);
 
 		/*
-		 * Reuse existing anon_vma if it has no vma and only one
-		 * anon_vma child.
+		 * Reuse existing anon_vma if its degree lower than two,
+		 * that means it has no vma and only one anon_vma child.
 		 *
-		 * Root anon_vma is never reused:
+		 * Do not chose parent anon_vma, otherwise first child
+		 * will always reuse it. Root anon_vma is never reused:
 		 * it has self-parent reference and at least one child.
 		 */
 		if (!dst->anon_vma && src->anon_vma &&
-		    anon_vma->num_children < 2 &&
-		    anon_vma->num_active_vmas == 0)
+		    anon_vma != src->anon_vma && anon_vma->degree < 2)
 			dst->anon_vma = anon_vma;
 	}
 	if (dst->anon_vma)
-		dst->anon_vma->num_active_vmas++;
+		dst->anon_vma->degree++;
 	unlock_anon_vma_root(root);
 	return 0;
 
@@ -357,7 +356,6 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
 	anon_vma = anon_vma_alloc();
 	if (!anon_vma)
 		goto out_error;
-	anon_vma->num_active_vmas++;
 	avc = anon_vma_chain_alloc(GFP_KERNEL);
 	if (!avc)
 		goto out_error_free_anon_vma;
@@ -378,7 +376,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
 	vma->anon_vma = anon_vma;
 	anon_vma_lock_write(anon_vma);
 	anon_vma_chain_link(vma, avc, anon_vma);
-	anon_vma->parent->num_children++;
+	anon_vma->parent->degree++;
 	anon_vma_unlock_write(anon_vma);
 
 	return 0;
@@ -410,7 +408,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma)
 		 * to free them outside the lock.
 		 */
 		if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) {
-			anon_vma->parent->num_children--;
+			anon_vma->parent->degree--;
 			continue;
 		}
 
@@ -418,7 +416,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma)
 		anon_vma_chain_free(avc);
 	}
 	if (vma->anon_vma)
-		vma->anon_vma->num_active_vmas--;
+		vma->anon_vma->degree--;
 	unlock_anon_vma_root(root);
 
 	/*
@@ -429,8 +427,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma)
 	list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
 		struct anon_vma *anon_vma = avc->anon_vma;
 
-		VM_WARN_ON(anon_vma->num_children);
-		VM_WARN_ON(anon_vma->num_active_vmas);
+		VM_WARN_ON(anon_vma->degree);
 		put_anon_vma(anon_vma);
 
 		list_del(&avc->same_vma);