diff --git a/include/linux/mm.h b/include/linux/mm.h
index 09b48af68699..c24c521e38a2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -787,6 +787,8 @@ static bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_l
 	return (vma->vm_lock_seq == *mm_lock_seq);
 }
 
+void __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq);
+
 /*
  * Begin writing to a VMA.
  * Exclude concurrent readers under the per-VMA lock until the currently
@@ -799,15 +801,7 @@ static inline void vma_start_write(struct vm_area_struct *vma)
 	if (__is_vma_write_locked(vma, &mm_lock_seq))
 		return;
 
-	down_write(&vma->vm_lock.lock);
-	/*
-	 * We should use WRITE_ONCE() here because we can have concurrent reads
-	 * from the early lockless pessimistic check in vma_start_read().
-	 * We don't really care about the correctness of that early check, but
-	 * we should use WRITE_ONCE() for cleanliness and to keep KCSAN happy.
-	 */
-	WRITE_ONCE(vma->vm_lock_seq, mm_lock_seq);
-	up_write(&vma->vm_lock.lock);
+	__vma_start_write(vma, mm_lock_seq);
 }
 
 static inline void vma_assert_write_locked(struct vm_area_struct *vma)
diff --git a/mm/memory.c b/mm/memory.c
index 6ef014220e09..f2f7dc215b6b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6353,6 +6353,20 @@ struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
 #endif
 
 #ifdef CONFIG_PER_VMA_LOCK
+void __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq)
+{
+	down_write(&vma->vm_lock.lock);
+	/*
+	 * We should use WRITE_ONCE() here because we can have concurrent reads
+	 * from the early lockless pessimistic check in vma_start_read().
+	 * We don't really care about the correctness of that early check, but
+	 * we should use WRITE_ONCE() for cleanliness and to keep KCSAN happy.
+	 */
+	WRITE_ONCE(vma->vm_lock_seq, mm_lock_seq);
+	up_write(&vma->vm_lock.lock);
+}
+EXPORT_SYMBOL_GPL(__vma_start_write);
+
 /*
  * Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be
  * stable and not isolated. If the VMA is not found or is being modified the