nd_info_block_reserve
rc = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
unsigned long reserve = nd_info_block_reserve() >> PAGE_SHIFT;
u32 reserve = nd_info_block_reserve();
rc = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
ret = devm_namespace_enable(dev, ndns, nd_info_block_reserve());