Hi Arnd, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: d635f6cc934bcd467c5d67148ece74632fd96abf commit: 250c1a694ff304e5d69e74ab32755eddcc2b8f65 ARM: pxa: convert to multiplatform date: 1 year ago config: arm-buildonly-randconfig-r005-20230521 compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project b0fb98227c90adf2536c9ad644a74d5e92961111) 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 arm cross compiling tool for clang build # apt-get install binutils-arm-linux-gnueabi # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=250c1a694ff304e5d69e74ab32755eddcc2b8f65 git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 250c1a694ff304e5d69e74ab32755eddcc2b8f65 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash arch/arm/mm/ If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot | Closes: https://lore.kernel.org/oe-kbuild-all/202305210314.5wey5E1W-lkp@intel.com/ All warnings (new ones prefixed by >>): >> arch/arm/mm/copypage-xsc3.c:64:6: warning: no previous prototype for function 'xsc3_mc_copy_user_highpage' [-Wmissing-prototypes] void xsc3_mc_copy_user_highpage(struct page *to, struct page *from, ^ arch/arm/mm/copypage-xsc3.c:64:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void xsc3_mc_copy_user_highpage(struct page *to, struct page *from, ^ static >> arch/arm/mm/copypage-xsc3.c:80:6: warning: no previous prototype for function 'xsc3_mc_clear_user_highpage' [-Wmissing-prototypes] void xsc3_mc_clear_user_highpage(struct page *page, unsigned long vaddr) ^ arch/arm/mm/copypage-xsc3.c:80:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void xsc3_mc_clear_user_highpage(struct page *page, unsigned long vaddr) ^ static 2 warnings generated. vim +/xsc3_mc_copy_user_highpage +64 arch/arm/mm/copypage-xsc3.c d73e60b7144a86 Russell King 2008-10-31 63 063b0a4207e43a Russell King 2008-10-31 @64 void xsc3_mc_copy_user_highpage(struct page *to, struct page *from, f00a75c094c340 Russell King 2009-10-05 65 unsigned long vaddr, struct vm_area_struct *vma) 063b0a4207e43a Russell King 2008-10-31 66 { 063b0a4207e43a Russell King 2008-10-31 67 void *kto, *kfrom; 063b0a4207e43a Russell King 2008-10-31 68 5472e862de2bc4 Cong Wang 2011-11-25 69 kto = kmap_atomic(to); 5472e862de2bc4 Cong Wang 2011-11-25 70 kfrom = kmap_atomic(from); 2725898fc9bb21 Russell King 2009-10-05 71 flush_cache_page(vma, vaddr, page_to_pfn(from)); 063b0a4207e43a Russell King 2008-10-31 72 xsc3_mc_copy_user_page(kto, kfrom); 5472e862de2bc4 Cong Wang 2011-11-25 73 kunmap_atomic(kfrom); 5472e862de2bc4 Cong Wang 2011-11-25 74 kunmap_atomic(kto); 063b0a4207e43a Russell King 2008-10-31 75 } 063b0a4207e43a Russell King 2008-10-31 76 d73e60b7144a86 Russell King 2008-10-31 77 /* d73e60b7144a86 Russell King 2008-10-31 78 * XScale optimised clear_user_page d73e60b7144a86 Russell King 2008-10-31 79 */ 303c6443659bc1 Russell King 2008-10-31 @80 void xsc3_mc_clear_user_highpage(struct page *page, unsigned long vaddr) d73e60b7144a86 Russell King 2008-10-31 81 { 5472e862de2bc4 Cong Wang 2011-11-25 82 void *ptr, *kaddr = kmap_atomic(page); 43ae286b7d4d8c Nicolas Pitre 2008-11-04 83 asm volatile ("\ c8a91428941b91 Arnd Bergmann 2022-04-04 84 .arch xscale \n\ 43ae286b7d4d8c Nicolas Pitre 2008-11-04 85 mov r1, %2 \n\ d73e60b7144a86 Russell King 2008-10-31 86 mov r2, #0 \n\ d73e60b7144a86 Russell King 2008-10-31 87 mov r3, #0 \n\ 303c6443659bc1 Russell King 2008-10-31 88 1: mcr p15, 0, %0, c7, c6, 1 @ invalidate line\n\ bc2eca9a682881 Nicolas Pitre 2018-11-09 89 strd r2, r3, [%0], #8 \n\ bc2eca9a682881 Nicolas Pitre 2018-11-09 90 strd r2, r3, [%0], #8 \n\ bc2eca9a682881 Nicolas Pitre 2018-11-09 91 strd r2, r3, [%0], #8 \n\ bc2eca9a682881 Nicolas Pitre 2018-11-09 92 strd r2, r3, [%0], #8 \n\ d73e60b7144a86 Russell King 2008-10-31 93 subs r1, r1, #1 \n\ 303c6443659bc1 Russell King 2008-10-31 94 bne 1b" 43ae286b7d4d8c Nicolas Pitre 2008-11-04 95 : "=r" (ptr) 43ae286b7d4d8c Nicolas Pitre 2008-11-04 96 : "0" (kaddr), "I" (PAGE_SIZE / 32) 303c6443659bc1 Russell King 2008-10-31 97 : "r1", "r2", "r3"); 5472e862de2bc4 Cong Wang 2011-11-25 98 kunmap_atomic(kaddr); d73e60b7144a86 Russell King 2008-10-31 99 } d73e60b7144a86 Russell King 2008-10-31 100 :::::: The code at line 64 was first introduced by commit :::::: 063b0a4207e43acbeff3d4b09f43e750e0212b48 [ARM] copypage: provide our own copy_user_highpage() :::::: TO: Russell King :::::: CC: Russell King -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki