7147724: G1: hang in SurrogateLockerThread::manipulatePLL Summary: Attempting to initiate a marking cycle when allocating a humongous object can, if a marking cycle is successfully initiated by another thread, result in the allocating thread spinning until the marking cycle is complete. Eliminate a deadlock between the main ConcurrentMarkThread, the SurrogateLocker thread, the VM thread, and a mutator thread waiting on the SecondaryFreeList_lock (while free regions are going to become available) by not manipulating the pending list lock during the prologue and epilogue of the cleanup pause. Reviewed-by: brutisso, jcoomes, tonyp

/*
 * @test WBApi
 * @summary verify that whitebox functions can be linked and executed
 * @run compile -J-XX:+UnlockDiagnosticVMOptions -J-XX:+WhiteBoxAPI WBApi.java
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI WBApi
 */

import sun.hotspot.WhiteBox;
public class WBApi {
    public static void main(String... args) {
        System.out.printf("args at: %x\n",WhiteBox.getWhiteBox().getObjectAddress(args));
    }
}