--- 2.5.69-mm3/mm/memory.c	2003-05-13 10:34:56.000000000 -0500
+++ 2.5.69-mm3-test/mm/memory.c	2003-05-13 17:39:45.000000000 -0500
@@ -1085,21 +1085,21 @@ static void vmtruncate_list(struct list_
 		len = end - start;
 
 		/* mapping wholly truncated? */
-		if (vma->vm_pgoff >= pgoff) {
-			zap_page_range(vma, start, len);
-			continue;
-		}
+		if (vma->vm_pgoff < pgoff) {
 
-		/* mapping wholly unaffected? */
-		len = len >> PAGE_SHIFT;
-		diff = pgoff - vma->vm_pgoff;
-		if (diff >= len)
-			continue;
-
-		/* Ok, partially affected.. */
-		start += diff << PAGE_SHIFT;
-		len = (len - diff) << PAGE_SHIFT;
+			/* mapping wholly unaffected? */
+			len = len >> PAGE_SHIFT;
+			diff = pgoff - vma->vm_pgoff;
+			if (diff >= len)
+				continue;
+
+			/* Ok, partially affected.. */
+			start += diff << PAGE_SHIFT;
+			len = (len - diff) << PAGE_SHIFT;
+		}
+		down_write(&vma->vm_mm->mmap_sem);
 		zap_page_range(vma, start, len);
+		up_write(&vma->vm_mm->mmap_sem);
 	}
 }