NON_LINEAR_REGION_ID
#define VMEMMAP_REGION_ID NON_LINEAR_REGION_ID(H_VMEMMAP_START)
BUILD_BUG_ON(NON_LINEAR_REGION_ID(H_VMALLOC_START) != 2);
region_id = NON_LINEAR_REGION_ID(ea);
#define VMALLOC_REGION_ID NON_LINEAR_REGION_ID(H_VMALLOC_START)
#define IO_REGION_ID NON_LINEAR_REGION_ID(H_KERN_IO_START)