Hi Mark, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 1e16624d7b4376797ede36e3c955375cf0f23298 commit: bccf1ec369ac126b0997d01a6e1deae00e2cf6b3 locking/atomics: atomic-instrumented: simplify ifdeffery date: 6 weeks ago config: arc-allyesconfig (attached as .config) compiler: arceb-elf-gcc (GCC) 9.3.0 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 # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bccf1ec369ac126b0997d01a6e1deae00e2cf6b3 git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout bccf1ec369ac126b0997d01a6e1deae00e2cf6b3 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All errors (new ones prefixed by >>): In file included from include/linux/atomic.h:80, from drivers/iommu/io-pgtable-arm.c:12: drivers/iommu/io-pgtable-arm.c: In function 'arm_lpae_install_table': >> include/linux/atomic-arch-fallback.h:60:32: error: implicit declaration of function 'arch_cmpxchg64'; did you mean 'arch_cmpxchg'? [-Werror=implicit-function-declaration] 60 | #define arch_cmpxchg64_relaxed arch_cmpxchg64 | ^~~~~~~~~~~~~~ include/asm-generic/atomic-instrumented.h:1261:2: note: in expansion of macro 'arch_cmpxchg64_relaxed' 1261 | arch_cmpxchg64_relaxed(__ai_ptr, __VA_ARGS__); \ | ^~~~~~~~~~~~~~~~~~~~~~ drivers/iommu/io-pgtable-arm.c:320:8: note: in expansion of macro 'cmpxchg64_relaxed' 320 | old = cmpxchg64_relaxed(ptep, curr, new); | ^~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +60 include/linux/atomic-arch-fallback.h 37f8173dd84936 Peter Zijlstra 2020-01-24 56 37f8173dd84936 Peter Zijlstra 2020-01-24 57 #ifndef arch_cmpxchg64_relaxed 37f8173dd84936 Peter Zijlstra 2020-01-24 58 #define arch_cmpxchg64_acquire arch_cmpxchg64 37f8173dd84936 Peter Zijlstra 2020-01-24 59 #define arch_cmpxchg64_release arch_cmpxchg64 29f006fdefe6f8 Peter Zijlstra 2020-08-29 @60 #define arch_cmpxchg64_relaxed arch_cmpxchg64 37f8173dd84936 Peter Zijlstra 2020-01-24 61 #else /* arch_cmpxchg64_relaxed */ 37f8173dd84936 Peter Zijlstra 2020-01-24 62 :::::: The code at line 60 was first introduced by commit :::::: 29f006fdefe6f88abde973a0b0f20d2704e93fd4 asm-generic/atomic: Add try_cmpxchg() fallbacks :::::: TO: Peter Zijlstra :::::: CC: Ingo Molnar --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org