2 files changed, 15 insertions, 14 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f31c75dc190e..f5487a86b154 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -628,12 +628,6 @@ struct vm_operations_struct {
 };
 
 #ifdef CONFIG_PER_VMA_LOCK
-static inline void vma_init_lock(struct vm_area_struct *vma)
-{
-	init_rwsem(&vma->lock);
-	vma->vm_lock_seq = -1;
-}
-
 /*
  * Try to read-lock a vma. The function is allowed to occasionally yield false
  * locked result to avoid performance overhead, in which case we fall back to
@@ -645,17 +639,17 @@ static inline bool vma_start_read(struct vm_area_struct *vma)
 	if (vma->vm_lock_seq == READ_ONCE(vma->vm_mm->mm_lock_seq))
 		return false;
 
-	if (unlikely(down_read_trylock(&vma->lock) == 0))
+	if (unlikely(down_read_trylock(&vma->vm_lock->lock) == 0))
 		return false;
 
 	/*
 	 * Overflow might produce false locked result.
 	 * False unlocked result is impossible because we modify and check
-	 * vma->vm_lock_seq under vma->lock protection and mm->mm_lock_seq
+	 * vma->vm_lock_seq under vma->vm_lock protection and mm->mm_lock_seq
 	 * modification invalidates all existing locks.
 	 */
 	if (unlikely(vma->vm_lock_seq == READ_ONCE(vma->vm_mm->mm_lock_seq))) {
-		up_read(&vma->lock);
+		up_read(&vma->vm_lock->lock);
 		return false;
 	}
 	return true;
@@ -664,7 +658,7 @@ static inline bool vma_start_read(struct vm_area_struct *vma)
 static inline void vma_end_read(struct vm_area_struct *vma)
 {
 	rcu_read_lock(); /* keeps vma alive till the end of up_read */
-	up_read(&vma->lock);
+	up_read(&vma->vm_lock->lock);
 	rcu_read_unlock();
 }
 
@@ -687,9 +681,9 @@ static inline void vma_start_write(struct vm_area_struct *vma)
 	if (__is_vma_write_locked(vma, &mm_lock_seq))
 		return;
 
-	down_write(&vma->lock);
+	down_write(&vma->vm_lock->lock);
 	vma->vm_lock_seq = mm_lock_seq;
-	up_write(&vma->lock);
+	up_write(&vma->vm_lock->lock);
 }
 
 static inline bool vma_try_start_write(struct vm_area_struct *vma)
@@ -740,6 +734,10 @@ static inline void vma_mark_detached(struct vm_area_struct *vma,
 
 #endif /* CONFIG_PER_VMA_LOCK */
 
+/*
+ * WARNING: vma_init does not initialize vma->vm_lock.
+ * Use vm_area_alloc()/vm_area_free() if vma needs locking.
+ */
 static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
 {
 	static const struct vm_operations_struct dummy_vm_ops = {};
@@ -749,7 +747,6 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
 	vma->vm_ops = &dummy_vm_ops;
 	INIT_LIST_HEAD(&vma->anon_vma_chain);
 	vma_mark_detached(vma, false);
-	vma_init_lock(vma);
 }
 
 /* Use when VMA is not part of the VMA tree and needs no locking */
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3a6cf4c2edd0..1b3031e95215 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -471,6 +471,10 @@ struct anon_vma_name {
 	char name[];
 };
 
+struct vma_lock {
+	struct rw_semaphore lock;
+};
+
 /*
  * This struct describes a virtual memory area. There is one of these
  * per VM-area/task. A VM area is any part of the process virtual memory
@@ -505,7 +509,7 @@ struct vm_area_struct {
 
 #ifdef CONFIG_PER_VMA_LOCK
 	int vm_lock_seq;
-	struct rw_semaphore lock;
+	struct vma_lock *vm_lock;
 
 	/* Flag to indicate areas detached from the mm->mm_mt tree */
 	bool detached;