tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 1216f02e46a46aad2a9c1c3bb29032f0b42eedac commit: b26e8f27253a47bff90972b987112fd8396e9b8d [12572/12985] powerpc/mem: Move cache flushing functions into mm/cacheflush.c config: powerpc64-randconfig-r026-20210415 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 6a18cc23efad410db48a3ccfc233d215de7d4cb9) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install powerpc64 cross compiling tool for clang build # apt-get install binutils-powerpc64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commi... git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git git fetch --no-tags linux-next master git checkout b26e8f27253a47bff90972b987112fd8396e9b8d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=powerpc64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): ^ arch/powerpc/include/asm/io.h:537:62: note: expanded from macro '__do_outl' #define __do_outl(val, port) writel(val,(PCI_IO_ADDR)_IO_BASE+port); ~~~~~~~~~~~~~~~~~~~~~^ In file included from arch/powerpc/mm/mem.c:15: In file included from include/linux/memblock.h:14: In file included from arch/powerpc/include/asm/dma.h:22: In file included from arch/powerpc/include/asm/io.h:619: arch/powerpc/include/asm/io-defs.h:43:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insb, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:616:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:161:1: note: expanded from here __do_insb ^ arch/powerpc/include/asm/io.h:556:56: note: expanded from macro '__do_insb' #define __do_insb(p, b, n) readsb((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from arch/powerpc/mm/mem.c:15: In file included from include/linux/memblock.h:14: In file included from arch/powerpc/include/asm/dma.h:22: In file included from arch/powerpc/include/asm/io.h:619: arch/powerpc/include/asm/io-defs.h:45:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insw, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:616:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:163:1: note: expanded from here __do_insw ^ arch/powerpc/include/asm/io.h:557:56: note: expanded from macro '__do_insw' #define __do_insw(p, b, n) readsw((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from arch/powerpc/mm/mem.c:15: In file included from include/linux/memblock.h:14: In file included from arch/powerpc/include/asm/dma.h:22: In file included from arch/powerpc/include/asm/io.h:619: arch/powerpc/include/asm/io-defs.h:47:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insl, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:616:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:165:1: note: expanded from here __do_insl ^ arch/powerpc/include/asm/io.h:558:56: note: expanded from macro '__do_insl' #define __do_insl(p, b, n) readsl((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from arch/powerpc/mm/mem.c:15: In file included from include/linux/memblock.h:14: In file included from arch/powerpc/include/asm/dma.h:22: In file included from arch/powerpc/include/asm/io.h:619: arch/powerpc/include/asm/io-defs.h:49:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsb, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:616:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:167:1: note: expanded from here __do_outsb ^ arch/powerpc/include/asm/io.h:559:58: note: expanded from macro '__do_outsb' #define __do_outsb(p, b, n) writesb((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from arch/powerpc/mm/mem.c:15: In file included from include/linux/memblock.h:14: In file included from arch/powerpc/include/asm/dma.h:22: In file included from arch/powerpc/include/asm/io.h:619: arch/powerpc/include/asm/io-defs.h:51:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsw, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:616:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:169:1: note: expanded from here __do_outsw ^ arch/powerpc/include/asm/io.h:560:58: note: expanded from macro '__do_outsw' #define __do_outsw(p, b, n) writesw((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from arch/powerpc/mm/mem.c:15: In file included from include/linux/memblock.h:14: In file included from arch/powerpc/include/asm/dma.h:22: In file included from arch/powerpc/include/asm/io.h:619: arch/powerpc/include/asm/io-defs.h:53:1: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsl, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:616:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:171:1: note: expanded from here __do_outsl ^ arch/powerpc/include/asm/io.h:561:58: note: expanded from macro '__do_outsl' #define __do_outsl(p, b, n) writesl((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ int __weak create_section_mapping(unsigned long start, unsigned long end, ^ arch/powerpc/mm/mem.c:53:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int __weak create_section_mapping(unsigned long start, unsigned long end, ^ static 13 errors generated. vim +/create_section_mapping +53 arch/powerpc/mm/mem.c bc02af93dd2bbdd Yasunori Goto 2006-06-27 52 4e00c5affdd4b04 Logan Gunthorpe 2020-04-10 @53 int __weak create_section_mapping(unsigned long start, unsigned long end, 4e00c5affdd4b04 Logan Gunthorpe 2020-04-10 54 int nid, pgprot_t prot) fecbfabe1dc9405 Benjamin Herrenschmidt 2016-07-05 55 { fecbfabe1dc9405 Benjamin Herrenschmidt 2016-07-05 56 return -ENODEV; fecbfabe1dc9405 Benjamin Herrenschmidt 2016-07-05 57 } fecbfabe1dc9405 Benjamin Herrenschmidt 2016-07-05 58 :::::: The code at line 53 was first introduced by commit :::::: 4e00c5affdd4b04e6392001716333971932f3d0c powerpc/mm: thread pgprot_t through create_section_mapping() :::::: TO: Logan Gunthorpe <logang(a)deltatee.com&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org