in bus.c [1281:1292]
static void dev_dax_release(struct device *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
struct dax_region *dax_region = dev_dax->region;
struct dax_device *dax_dev = dev_dax->dax_dev;
put_dax(dax_dev);
free_dev_dax_id(dev_dax);
dax_region_put(dax_region);
kfree(dev_dax->pgmap);
kfree(dev_dax);
}