During the Concurrent Mark phase, G1 may increase the marking stack size on demand, starting from a minimum and potentially reaching a maximum value as defined by the `-XX:MarkStackSize` and `-XX:MarkStackSizeMax` command line options.

Previously, G1 has been unable to grow the marking stack during the Reference Processing phase in the Remark pause, which could result in a mark stack overflow error that exits the virtual machine before reaching the limit imposed by `-XX:MarkStackSizeMax`.

With this update, the marking stack is allowed to also expand during Reference Processing, preventing this premature overflow error.