diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index bad746b..0d105ae 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -155,22 +155,14 @@
 EXPORT_SYMBOL_GPL(xip_file_read);
 
 /*
- * __xip_unmap is invoked from xip_unmap and
- * xip_write
+ * __xip_unmap is invoked from xip_unmap and xip_write
  *
  * This function walks all vmas of the address_space and unmaps the
  * __xip_sparse_page when found at pgoff.
  */
-static void
-__xip_unmap (struct address_space * mapping,
-		     unsigned long pgoff)
+static void __xip_unmap(struct address_space * mapping, unsigned long pgoff)
 {
 	struct vm_area_struct *vma;
-	struct mm_struct *mm;
-	unsigned long address;
-	pte_t *pte;
-	pte_t pteval;
-	spinlock_t *ptl;
 	struct page *page;
 	unsigned count;
 	int locked = 0;
@@ -182,11 +174,14 @@
 		return;
 
 retry:
-	i_mmap_lock_write(mapping);
+	i_mmap_lock_read(mapping);
 	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
-		mm = vma->vm_mm;
-		address = vma->vm_start +
+		pte_t *pte, pteval;
+		spinlock_t *ptl;
+		struct mm_struct *mm = vma->vm_mm;
+		unsigned long address = vma->vm_start +
 			((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+
 		BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 		pte = page_check_address(page, mm, address, &ptl, 1);
 		if (pte) {
@@ -202,7 +197,7 @@
 			page_cache_release(page);
 		}
 	}
-	i_mmap_unlock_write(mapping);
+	i_mmap_unlock_read(mapping);
 
 	if (locked) {
 		mutex_unlock(&xip_sparse_mutex);