7012642: G1: JumbleGC002 test aborts with segmentation violation due to uncaught stack overflow Summary: With recent G1 allocation path changes, the value of StackShadowPages in fast debug builds of the JVM, is no longer large enough to prevent the JVM C++ code from touching the stack guard pages. Increase the value of StackShadowPages to a suitable value. Reviewed-by: ysr, tonyp, coleenp