diff --git a/fs/dax.c b/fs/dax.c
index 74838c4..9ef9b80 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -529,7 +529,7 @@
 	if ((pmd_addr + PMD_SIZE) > vma->vm_end)
 		return VM_FAULT_FALLBACK;
 
-	pgoff = ((pmd_addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+	pgoff = linear_page_index(vma, pmd_addr);
 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (pgoff >= size)
 		return VM_FAULT_SIGBUS;