1 files changed, 10 insertions, 2 deletions
diff --git a/rts/sm/GCAux.c b/rts/sm/GCAux.c
index 650dc2c1df..11080c1f22 100644
--- a/rts/sm/GCAux.c
+++ b/rts/sm/GCAux.c
@@ -60,6 +60,14 @@ isAlive(StgClosure *p)
     // ignore closures in generations that we're not collecting.
     bd = Bdescr((P_)q);
 
+    // isAlive is used when scavenging moving generations, before the mark
+    // phase. Because we don't know alive-ness of objects before the mark phase
+    // we have to conservatively treat objects in the non-moving generation as
+    // alive here.
+    if (bd->flags & BF_NONMOVING) {
+        return p;
+    }
+
     // if it's a pointer into to-space, then we're done
     if (bd->flags & BF_EVACUATED) {
         return p;
@@ -140,14 +148,14 @@ markCAFs (evac_fn evac, void *user)
     StgIndStatic *c;
 
     for (c = dyn_caf_list;
-         c != (StgIndStatic*)END_OF_CAF_LIST;
+         ((StgWord) c | STATIC_FLAG_LIST) != (StgWord)END_OF_CAF_LIST;
          c = (StgIndStatic *)c->static_link)
     {
         c = (StgIndStatic *)UNTAG_STATIC_LIST_PTR(c);
         evac(user, &c->indirectee);
     }
     for (c = revertible_caf_list;
-         c != (StgIndStatic*)END_OF_CAF_LIST;
+         ((StgWord) c | STATIC_FLAG_LIST) != (StgWord)END_OF_CAF_LIST;
          c = (StgIndStatic *)c->static_link)
     {
         c = (StgIndStatic *)UNTAG_STATIC_LIST_PTR(c);