IoAllocateIrp创建的IRP用IoFreeIrp删除蓝屏的问题

本人在看windows驱动开发技术详解，作者在第十一章提到用IoAllocateIrp内核函数创建IRP时，需要程序员调用IoFreeIrp内核函数删除IRP对象。
下面是驱动程序B调用驱动程序A的一段代码：
驱动B的部分代码：
NTSTATUS HelloDDKRead(IN PDEVICE_OBJECT pDevObj,IN PIRP pIrp)
{
KdPrint(("DriverB:Enter B HelloDDKRead\n"));
NTSTATUS ntStatus = STATUS_SUCCESS;

UNICODE_STRING DeviceName;
RtlInitUnicodeString( &DeviceName, L"\\Device\\MyDDKDeviceA" );

PDEVICE_OBJECT DeviceObject = NULL;
PFILE_OBJECT FileObject = NULL;
//得到设备对象指针
ntStatus = IoGetDeviceObjectPointer(&DeviceName,FILE_ALL_ACCESS,&FileObject,&DeviceObject);

KdPrint(("DriverB:FileObject:%x\n",FileObject));
KdPrint(("DriverB:DeviceObject:%x\n",DeviceObject));

if (!NT_SUCCESS(ntStatus))
{
KdPrint(("DriverB:IoGetDeviceObjectPointer() 0x%x\n", ntStatus ));
ntStatus = STATUS_UNSUCCESSFUL;
// 完成IRP
pIrp->IoStatus.Status = ntStatus;
pIrp->IoStatus.Information = 0; // bytes xfered
IoCompleteRequest( pIrp, IO_NO_INCREMENT );
KdPrint(("DriverB:Leave B HelloDDKRead\n"));

return ntStatus;
}

KEVENT event;
KeInitializeEvent(&event,NotificationEvent,FALSE);

PIRP pNewIrp = IoAllocateIrp(DeviceObject->StackSize,FALSE);
KdPrint(("pNewIrp->UserEvent :%x\n",pNewIrp->UserEvent));
pNewIrp->UserEvent = &event;

IO_STATUS_BLOCK status_block;
pNewIrp->UserIosb = &status_block;
pNewIrp->Tail.Overlay.Thread = PsGetCurrentThread();

//因为DriverA是BUFFER IO设备
pNewIrp->AssociatedIrp.SystemBuffer = NULL;

KdPrint(("DriverB:pNewIrp:%x\n",pNewIrp));

PIO_STACK_LOCATION stack = IoGetNextIrpStackLocation(pNewIrp);
stack->MajorFunction = IRP_MJ_READ;
stack->MinorFunction=IRP_MN_NORMAL;//0
stack->FileObject = FileObject;

//调用DriverA驱动
NTSTATUS status = IoCallDriver(DeviceObject,pNewIrp);

if (status == STATUS_PENDING) {
status = KeWaitForSingleObject(
&event,
Executive,
KernelMode,
FALSE, // Not alertable
NULL);
KdPrint(("STATUS_PENDING\n"));
}

ObDereferenceObject( FileObject );
IoFreeIrp(pNewIrp);//该句有问题！！！！

ntStatus = STATUS_SUCCESS;
// 完成IRP
pIrp->IoStatus.Status = ntStatus;
pIrp->IoStatus.Information = 0; // bytes xfered
IoCompleteRequest( pIrp, IO_NO_INCREMENT );
KdPrint(("DriverB:Leave B HelloDDKRead\n"));
return ntStatus;
}

驱动A中对相应IRP响应函数先把IRP挂起，然后定时三秒后结束IRP，部分代码如下：

NTSTATUS HelloDDKRead(IN PDEVICE_OBJECT pDevObj,IN PIRP pIrp)
{
KdPrint(("DriverA:Enter A HelloDDKRead\n"));

PDEVICE_EXTENSION pDevExt = (PDEVICE_EXTENSION)
pDevObj->DeviceExtension;

//将IRP设置为挂起
IoMarkIrpPending(pIrp);

//将挂起的IRP记录下来
pDevExt->currentPendingIRP = pIrp;

//定义3秒后将IRP_MJ_READ的IRP完成
ULONG ulMicroSecond = 3000000;

//将32位整数转化成64位整数
LARGE_INTEGER timeout = RtlConvertLongToLargeInteger(-10*ulMicroSecond);

KeSetTimer(
&pDevExt->pollingTimer,
timeout,
&pDevExt->pollingDPC );

KdPrint(("DriverA:Leave A HelloDDKRead\n"));

//返回pending状态
return STATUS_PENDING;
}

#pragma LOCKEDCODE
VOID OnTimerDpc( IN PKDPC pDpc,
IN PVOID pContext,
IN PVOID SysArg1,
IN PVOID SysArg2 )
{
PDEVICE_OBJECT pDevObj = (PDEVICE_OBJECT)pContext;
PDEVICE_EXTENSION pdx = (PDEVICE_EXTENSION)pDevObj->DeviceExtension;

PIRP currentPendingIRP = pdx->currentPendingIRP;

KdPrint(("DriverA:complete the Driver A IRP_MJ_READ irp!\n"));

//设置完成状态为STATUS_SUCCESS
currentPendingIRP->IoStatus.Status = STATUS_SUCCESS;
currentPendingIRP->IoStatus.Information = 0; // bytes xfered
IoCompleteRequest( currentPendingIRP, IO_NO_INCREMENT );
}

问题是上面驱动B的红色标注的代码IoFreeIrp(pNewIrp);有这行代码会蓝屏，去掉这行代码，程序没有蓝屏错误，张帆的书上没有这行代码，但是配套光盘上面有。查阅ddk帮助，好像说必须设置完成例程用来释放IRP，初学驱动，刚开始看书，完成例程我还没有看到，请各位指点下，解释下为什么蓝屏，多谢。