in bus.c [630:646]
static void unregister_dax_mapping(void *data)
{
struct device *dev = data;
struct dax_mapping *mapping = to_dax_mapping(dev);
struct dev_dax *dev_dax = to_dev_dax(dev->parent);
struct dax_region *dax_region = dev_dax->region;
dev_dbg(dev, "%s\n", __func__);
device_lock_assert(dax_region->dev);
dev_dax->ranges[mapping->range_id].mapping = NULL;
mapping->range_id = -1;
device_del(dev);
put_device(dev);
}