static vm_fault_t snd_pcm_mmap_control_fault(struct vm_fault *vmf)
{
	struct snd_pcm_substream *substream = vmf->vma->vm_private_data;
	struct snd_pcm_runtime *runtime;
	
	if (substream == NULL)
		return VM_FAULT_SIGBUS;
	runtime = substream->runtime;
	vmf->page = virt_to_page(runtime->control);
	get_page(vmf->page);
	return 0;
}
static vm_fault_t snd_pcm_mmap_control_fault(struct vm_fault *vmf)
{
	struct snd_pcm_substream *substream = vmf->vma->vm_private_data;
	struct snd_pcm_runtime *runtime;
	
	if (substream == NULL)
		return VM_FAULT_SIGBUS;
	runtime = substream->runtime;
	vmf->page = virt_to_page(runtime->control);
	get_page(vmf->page);
	return 0;
}