=== modified file 'src/alloc.c'
--- src/alloc.c	2012-09-13 05:18:26 +0000
+++ src/alloc.c	2012-09-14 11:11:54 +0000
@@ -5865,32 +5865,6 @@
     mark_buffer (buffer->base_buffer);
 }
 
-/* Remove killed buffers or items whose car is a killed buffer from
-   LIST, and mark other items. Return changed LIST, which is marked.  */
-
-static Lisp_Object
-mark_discard_killed_buffers (Lisp_Object list)
-{
-  Lisp_Object tail, *prev = &list;
-
-  for (tail = list; CONSP (tail) && !CONS_MARKED_P (XCONS (tail));
-       tail = XCDR (tail))
-    {
-      Lisp_Object tem = XCAR (tail);
-      if (CONSP (tem))
-	tem = XCAR (tem);
-      if (BUFFERP (tem) && !BUFFER_LIVE_P (XBUFFER (tem)))
-	*prev = XCDR (tail);
-      else
-	{
-	  CONS_MARK (XCONS (tail));
-	  mark_object (XCAR (tail));
-	  prev = &XCDR_AS_LVALUE (tail);
-	}
-    }
-  return list;
-}
-
 /* Determine type of generic Lisp_Object and mark it accordingly.  */
 
 void
@@ -6034,24 +6008,12 @@
 	  case PVEC_WINDOW:
 	    {
 	      struct window *w = (struct window *) ptr;
-	      bool leaf = NILP (w->hchild) && NILP (w->vchild);
-
-	      /* For live windows, Lisp code filters out killed buffers
-		 from both buffer lists.  For dead windows, we do it here
-		 in attempt to help GC to reclaim killed buffers faster.  */
-	      if (leaf && NILP (w->buffer))
-		{
-		  wset_prev_buffers
-		    (w, mark_discard_killed_buffers (w->prev_buffers));
-		  wset_next_buffers
-		    (w, mark_discard_killed_buffers (w->next_buffers));
-		}
 
 	      mark_vectorlike (ptr);
 	      /* Mark glyphs for leaf windows.  Marking window
 		 matrices is sufficient because frame matrices
 		 use the same glyph memory.  */
-	      if (leaf && w->current_matrix)
+	      if (NILP (w->hchild) && NILP (w->vchild) && w->current_matrix)
 		{
 		  mark_glyph_matrix (w->current_matrix);
 		  mark_glyph_matrix (w->desired_matrix);

=== modified file 'src/window.c'
--- src/window.c	2012-09-11 15:42:50 +0000
+++ src/window.c	2012-09-14 12:09:06 +0000
@@ -3988,6 +3988,31 @@
   return new;
 }
 
+/* Reset W's fields so WINDOW_VALID_P is non-zero for W.  */
+
+static void
+kill_window (struct window *w)
+{
+  if (!NILP (w->vchild))
+    {
+      delete_all_child_windows (w->vchild);
+      wset_vchild (w, Qnil);
+    }
+  else if (!NILP (w->hchild))
+    {
+      delete_all_child_windows (w->hchild);
+      wset_hchild (w, Qnil);
+    }
+  else if (!NILP (w->buffer))
+    {
+      unshow_buffer (w);
+      unchain_marker (XMARKER (w->pointm));
+      unchain_marker (XMARKER (w->start));
+      wset_buffer (w, Qnil);
+    }
+  wset_prev_buffers (w, Qnil);
+  wset_next_buffers (w, Qnil);
+}
 
 DEFUN ("delete-window-internal", Fdelete_window_internal, Sdelete_window_internal, 1, 1, 0,
        doc: /* Remove WINDOW from its frame.
@@ -4078,23 +4103,8 @@
       wset_next (w, Qnil);  /* Don't delete w->next too.  */
       free_window_matrices (w);
 
-      if (!NILP (w->vchild))
-	{
-	  delete_all_child_windows (w->vchild);
-	  wset_vchild (w, Qnil);
-	}
-      else if (!NILP (w->hchild))
-	{
-	  delete_all_child_windows (w->hchild);
-	  wset_hchild (w, Qnil);
-	}
-      else if (!NILP (w->buffer))
-	{
-	  unshow_buffer (w);
-	  unchain_marker (XMARKER (w->pointm));
-	  unchain_marker (XMARKER (w->start));
-	  wset_buffer (w, Qnil);
-	}
+      /* W is really dead after this.  */
+      kill_window (w);
 
       if (NILP (s->prev) && NILP (s->next))
 	  /* A matrjoshka where SIBLING has become the only child of
@@ -5486,6 +5496,7 @@
   Lisp_Object parent, prev;
   Lisp_Object start_at_line_beg;
   Lisp_Object display_table;
+  Lisp_Object prev_buffers, next_buffers;
   Lisp_Object left_margin_cols, right_margin_cols;
   Lisp_Object left_fringe_width, right_fringe_width, fringes_outside_margins;
   Lisp_Object scroll_bar_width, vertical_scroll_bar_type, dedicated;
@@ -5726,6 +5737,8 @@
 	  w->hscroll = XFASTINT (p->hscroll);
 	  w->min_hscroll = XFASTINT (p->min_hscroll);
 	  wset_display_table (w, p->display_table);
+	  wset_prev_buffers (w, p->prev_buffers);
+	  wset_next_buffers (w, p->next_buffers);
 	  wset_left_margin_cols (w, p->left_margin_cols);
 	  wset_right_margin_cols (w, p->right_margin_cols);
 	  wset_left_fringe_width (w, p->left_fringe_width);
@@ -5926,23 +5939,8 @@
   /* See Fset_window_configuration for excuse.  */
   wset_total_lines (w, w->buffer);
 
-  if (!NILP (w->vchild))
-    {
-      delete_all_child_windows (w->vchild);
-      wset_vchild (w, Qnil);
-    }
-  else if (!NILP (w->hchild))
-    {
-      delete_all_child_windows (w->hchild);
-      wset_hchild (w, Qnil);
-    }
-  else if (!NILP (w->buffer))
-    {
-      unshow_buffer (w);
-      unchain_marker (XMARKER (w->pointm));
-      unchain_marker (XMARKER (w->start));
-      wset_buffer (w, Qnil);
-    }
+  /* W is really dead after this.  */
+  kill_window (w);
 
   Vwindow_list = Qnil;
 }
@@ -6045,6 +6043,8 @@
       XSETFASTINT (p->hscroll, w->hscroll);
       XSETFASTINT (p->min_hscroll, w->min_hscroll);
       p->display_table = w->display_table;
+      p->prev_buffers = w->prev_buffers;
+      p->next_buffers = w->next_buffers;
       p->left_margin_cols = w->left_margin_cols;
       p->right_margin_cols = w->right_margin_cols;
       p->left_fringe_width = w->left_fringe_width;