diff --git a/fs/dax.c b/fs/dax.c
index 9ef9b80cc1323d07bab14b90bbef956825dd1ed0..ed54efedade621c86facd108f91dfa623ed958a5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -554,6 +554,25 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
 		goto fallback;
 
+	if (buffer_unwritten(&bh) || buffer_new(&bh)) {
+		int i;
+		for (i = 0; i < PTRS_PER_PMD; i++)
+			clear_page(kaddr + i * PAGE_SIZE);
+		count_vm_event(PGMAJFAULT);
+		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+		result |= VM_FAULT_MAJOR;
+	}
+
+	/*
+	 * If we allocated new storage, make sure no process has any
+	 * zero pages covering this hole
+	 */
+	if (buffer_new(&bh)) {
+		i_mmap_unlock_write(mapping);
+		unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
+		i_mmap_lock_write(mapping);
+	}
+
 	/*
 	 * If a truncate happened while we were allocating blocks, we may
 	 * leave blocks allocated to the file that are beyond EOF.  We can't
@@ -568,13 +587,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	if ((pgoff | PG_PMD_COLOUR) >= size)
 		goto fallback;
 
-	/*
-	 * If we allocated new storage, make sure no process has any
-	 * zero pages covering this hole
-	 */
-	if (buffer_new(&bh))
-		unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
-
 	if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
 		spinlock_t *ptl;
 		pmd_t entry;
@@ -605,15 +617,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
 			goto fallback;
 
-		if (buffer_unwritten(&bh) || buffer_new(&bh)) {
-			int i;
-			for (i = 0; i < PTRS_PER_PMD; i++)
-				clear_page(kaddr + i * PAGE_SIZE);
-			count_vm_event(PGMAJFAULT);
-			mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
-			result |= VM_FAULT_MAJOR;
-		}
-
 		result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
 	}
 
diff --git a/mm/memory.c b/mm/memory.c
index 320c42e95e6951df5ee014cf72f18acee23696a5..ce8e983f3c4dbfa036449d3536ce61a697c051dd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2426,17 +2426,10 @@ void unmap_mapping_range(struct address_space *mapping,
 	if (details.last_index < details.first_index)
 		details.last_index = ULONG_MAX;
 
-
-	/*
-	 * DAX already holds i_mmap_lock to serialise file truncate vs
-	 * page fault and page fault vs page fault.
-	 */
-	if (!IS_DAX(mapping->host))
-		i_mmap_lock_write(mapping);
+	i_mmap_lock_write(mapping);
 	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
-	if (!IS_DAX(mapping->host))
-		i_mmap_unlock_write(mapping);
+	i_mmap_unlock_write(mapping);
 }
 EXPORT_SYMBOL(unmap_mapping_range);