[kbuild-all] [linux-next:master 2090/2633] include/linux/mm.h:171:10: warning: no case matching constant switch condition '128'

tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: ec85c95b0c90a17413901b018e8ade7b9eae7cad commit: 07f9193834d0574e4b0ff93b6d3b674c9534bf7d [2090/2633] mm/thp: make ALLOC_SPLIT_PTLOCKS dependent on USE_SPLIT_PTE_PTLOCKS config: x86_64-randconfig-a013-20210512 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project a0fed635fe1701470062495a6ffee1c608f3f1bc) 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 x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-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 07f9193834d0574e4b0ff93b6d3b674c9534bf7d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): In file included from arch/x86/kernel/asm-offsets.c:13: In file included from include/linux/suspend.h:5: In file included from include/linux/swap.h:9: In file included from include/linux/memcontrol.h:13: In file included from include/linux/cgroup.h:28: In file included from include/linux/cgroup-defs.h:22: In file included from include/linux/bpf-cgroup.h:5: In file included from include/linux/bpf.h:20: In file included from include/linux/kallsyms.h:12: switch (sizeof(struct page)) { ^~~~~~~~~~~~~~~~~~~ 1 warning generated. -- In file included from arch/x86/entry/vdso/vma.c:7: switch (sizeof(struct page)) { ^~~~~~~~~~~~~~~~~~~ arch/x86/entry/vdso/vma.c:35:19: warning: no previous prototype for function 'arch_get_vdso_data' [-Wmissing-prototypes] struct vdso_data *arch_get_vdso_data(void *vvar_page) ^ arch/x86/entry/vdso/vma.c:35:1: note: declare 'static' if the function is not intended to be used outside of this translation unit struct vdso_data *arch_get_vdso_data(void *vvar_page) ^ static 2 warnings generated. -- In file included from arch/x86/kernel/asm-offsets.c:13: In file included from include/linux/suspend.h:5: In file included from include/linux/swap.h:9: In file included from include/linux/memcontrol.h:13: In file included from include/linux/cgroup.h:28: In file included from include/linux/cgroup-defs.h:22: In file included from include/linux/bpf-cgroup.h:5: In file included from include/linux/bpf.h:20: In file included from include/linux/kallsyms.h:12: switch (sizeof(struct page)) { ^~~~~~~~~~~~~~~~~~~ 1 warning generated. vim +/128 +171 include/linux/mm.h 593befa6ab74a8 Dominik Dingel 2014-10-23 147 a4a3ede2132ae0 Pavel Tatashin 2017-11-15 148 /* a4a3ede2132ae0 Pavel Tatashin 2017-11-15 149 * On some architectures it is expensive to call memset() for small sizes. 5470dea49f5382 Alexander Duyck 2019-05-13 150 * If an architecture decides to implement their own version of 5470dea49f5382 Alexander Duyck 2019-05-13 151 * mm_zero_struct_page they should wrap the defines below in a #ifndef and 5470dea49f5382 Alexander Duyck 2019-05-13 152 * define their own version of this macro in <asm/pgtable.h> a4a3ede2132ae0 Pavel Tatashin 2017-11-15 153 */ 5470dea49f5382 Alexander Duyck 2019-05-13 154 #if BITS_PER_LONG == 64 5470dea49f5382 Alexander Duyck 2019-05-13 155 /* This function must be updated when the size of struct page grows above 80 5470dea49f5382 Alexander Duyck 2019-05-13 156 * or reduces below 56. The idea that compiler optimizes out switch() 5470dea49f5382 Alexander Duyck 2019-05-13 157 * statement, and only leaves move/store instructions. Also the compiler can 5470dea49f5382 Alexander Duyck 2019-05-13 158 * combine write statments if they are both assignments and can be reordered, 5470dea49f5382 Alexander Duyck 2019-05-13 159 * this can result in several of the writes here being dropped. 5470dea49f5382 Alexander Duyck 2019-05-13 160 */ 5470dea49f5382 Alexander Duyck 2019-05-13 161 #define mm_zero_struct_page(pp) __mm_zero_struct_page(pp) 5470dea49f5382 Alexander Duyck 2019-05-13 162 static inline void __mm_zero_struct_page(struct page *page) 5470dea49f5382 Alexander Duyck 2019-05-13 163 { 5470dea49f5382 Alexander Duyck 2019-05-13 164 unsigned long *_pp = (void *)page; 5470dea49f5382 Alexander Duyck 2019-05-13 165 5470dea49f5382 Alexander Duyck 2019-05-13 166 /* Check that struct page is either 56, 64, 72, or 80 bytes */ 5470dea49f5382 Alexander Duyck 2019-05-13 167 BUILD_BUG_ON(sizeof(struct page) & 7); 5470dea49f5382 Alexander Duyck 2019-05-13 168 BUILD_BUG_ON(sizeof(struct page) < 56); 5470dea49f5382 Alexander Duyck 2019-05-13 169 BUILD_BUG_ON(sizeof(struct page) > 80); 5470dea49f5382 Alexander Duyck 2019-05-13 170 5470dea49f5382 Alexander Duyck 2019-05-13 @171 switch (sizeof(struct page)) { 5470dea49f5382 Alexander Duyck 2019-05-13 172 case 80: df561f6688fef7 Gustavo A. R. Silva 2020-08-23 173 _pp[9] = 0; df561f6688fef7 Gustavo A. R. Silva 2020-08-23 174 fallthrough; 5470dea49f5382 Alexander Duyck 2019-05-13 175 case 72: df561f6688fef7 Gustavo A. R. Silva 2020-08-23 176 _pp[8] = 0; df561f6688fef7 Gustavo A. R. Silva 2020-08-23 177 fallthrough; 5470dea49f5382 Alexander Duyck 2019-05-13 178 case 64: df561f6688fef7 Gustavo A. R. Silva 2020-08-23 179 _pp[7] = 0; df561f6688fef7 Gustavo A. R. Silva 2020-08-23 180 fallthrough; 5470dea49f5382 Alexander Duyck 2019-05-13 181 case 56: 5470dea49f5382 Alexander Duyck 2019-05-13 182 _pp[6] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 183 _pp[5] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 184 _pp[4] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 185 _pp[3] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 186 _pp[2] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 187 _pp[1] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 188 _pp[0] = 0; 5470dea49f5382 Alexander Duyck 2019-05-13 189 } 5470dea49f5382 Alexander Duyck 2019-05-13 190 } 5470dea49f5382 Alexander Duyck 2019-05-13 191 #else a4a3ede2132ae0 Pavel Tatashin 2017-11-15 192 #define mm_zero_struct_page(pp) ((void)memset((pp), 0, sizeof(struct page))) a4a3ede2132ae0 Pavel Tatashin 2017-11-15 193 #endif a4a3ede2132ae0 Pavel Tatashin 2017-11-15 194 :::::: The code at line 171 was first introduced by commit :::::: 5470dea49f5382257c242ac617d908267727f1a8 mm: use mm_zero_struct_page from SPARC on all 64b architectures :::::: TO: Alexander Duyck <alexander.h.duyck(a)linux.intel.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