1 files changed, 4 insertions, 0 deletions
diff --git a/rts/sm/Scav.c b/rts/sm/Scav.c
index b046f39ad5..7a799d6be6 100644
--- a/rts/sm/Scav.c
+++ b/rts/sm/Scav.c
@@ -1300,6 +1300,10 @@ scavenge_one(StgPtr p)
     }
 
     case WEAK:
+        // This WEAK object will not be considered by tidyWeakList during this
+        // collection because it is in a generation >= N, but it is on the
+        // mutable list so we must evacuate all of its pointers because some
+        // of them may point into a younger generation.
         scavengeLiveWeak((StgWeak *)p);
         break;