1 files changed, 18 insertions, 2 deletions

diff --git a/mark.c b/mark.c
index 72fdec6a..139ca2b9 100644
--- a/mark.c
+++ b/mark.c
@@ -116,6 +116,7 @@ GC_INNER size_t GC_mark_stack_size = 0;
 GC_INNER mark_state_t GC_mark_state = MS_NONE;
 
 GC_INNER GC_bool GC_mark_stack_too_small = FALSE;
+GC_INNER GC_bool GC_mark_stack_empty_called = FALSE;
 
 static struct hblk * scan_ptr;
 
@@ -400,11 +401,26 @@ static void alloc_mark_stack(size_t);
                 MARK_FROM_MARK_STACK();
                 break;
             } else {
-                GC_mark_state = MS_NONE;
                 if (GC_mark_stack_too_small) {
+                    GC_mark_state = MS_NONE;
                     alloc_mark_stack(2*GC_mark_stack_size);
+                    return(TRUE);
+                } else {
+                  GC_mark_stack_empty_proc mark_stack_empty_proc = GC_get_mark_stack_empty();
+                  if (GC_mark_stack_empty_called || !mark_stack_empty_proc) {
+                    GC_mark_state = MS_NONE;
+                    GC_mark_stack_empty_called = FALSE;
+                    return(TRUE);
+                  } else {
+                    if (mark_stack_empty_proc != 0)
+                      mark_stack_empty_proc();
+
+                    /* break below here loops us around the mark phase once again */
+                    /* to process any items push by the callback */
+                    GC_mark_stack_empty_called = TRUE;
+                  }
                 }
-                return(TRUE);
+                break;
             }
 
         case MS_INVALID: