014b020475d4 ("s390/mm: cleanup phys_to_pfn() and friends")
75f195420a98 ("s390/mm: add missing pfn_to_kaddr helper")
16f486417160 ("s390/mm: add missing virt_to_pfn() etc. helper functions")
3d84683bd737 ("s390: introduce page_to_virt() and pfn_to_virt()")