tree: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git kcsan/rework head: d23e0222d49db5884782997974d9d7449d739e5b commit: d23e0222d49db5884782997974d9d7449d739e5b [8/8] kcsan: report observed value changes config: x86_64-randconfig-a016-20200914 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 3ed89b51da38f081fedb57727076262abb81d149) 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 git checkout d23e0222d49db5884782997974d9d7449d739e5b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross 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 >>): hex_len, old, hex_len, new); ^~~ include/linux/printk.h:339:33: note: expanded from macro 'pr_err' printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__) ~~~ ^~~~~~~~~~~ kernel/kcsan/report.c:415:28: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat] hex_len, old, hex_len, new); ^~~ include/linux/printk.h:339:33: note: expanded from macro 'pr_err' printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__) ~~~ ^~~~~~~~~~~ kernel/kcsan/report.c:417:14: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat] hex_len, diff, hex_len, mask); ^~~~ include/linux/printk.h:339:33: note: expanded from macro 'pr_err' printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__) ~~~ ^~~~~~~~~~~ kernel/kcsan/report.c:417:29: warning: format specifies type 'unsigned long' but the argument has type 'u64' (aka 'unsigned long long') [-Wformat] hex_len, diff, hex_len, mask); ^~~~ include/linux/printk.h:339:33: note: expanded from macro 'pr_err' printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__) ~~~ ^~~~~~~~~~~ 4 warnings generated. # https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?id... git remote add mark-rutland https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git git fetch --no-tags mark-rutland kcsan/rework git checkout d23e0222d49db5884782997974d9d7449d739e5b vim +415 kernel/kcsan/report.c 322 323 static void print_report(enum kcsan_value_change value_change, 324 const struct access_info *ai, 325 const struct other_info *other_info, 326 u64 old, u64 new, u64 mask) 327 { 328 unsigned long stack_entries[NUM_STACK_ENTRIES] = { 0 }; 329 int num_stack_entries = stack_trace_save(stack_entries, NUM_STACK_ENTRIES, 1); 330 int skipnr = get_stack_skipnr(stack_entries, num_stack_entries); 331 unsigned long this_frame = stack_entries[skipnr]; 332 unsigned long other_frame = 0; 333 int other_skipnr = 0; /* silence uninit warnings */ 334 335 /* 336 * Must check report filter rules before starting to print. 337 */ 338 if (skip_report(KCSAN_VALUE_CHANGE_TRUE, stack_entries[skipnr])) 339 return; 340 341 if (other_info) { 342 other_skipnr = get_stack_skipnr(other_info->stack_entries, 343 other_info->num_stack_entries); 344 other_frame = other_info->stack_entries[other_skipnr]; 345 346 /* @value_change is only known for the other thread */ 347 if (skip_report(value_change, other_frame)) 348 return; 349 } 350 351 if (rate_limit_report(this_frame, other_frame)) 352 return; 353 354 /* Print report header. */ 355 pr_err("==================================================================\n"); 356 if (other_info) { 357 int cmp; 358 359 /* 360 * Order functions lexographically for consistent bug titles. 361 * Do not print offset of functions to keep title short. 362 */ 363 cmp = sym_strcmp((void *)other_frame, (void *)this_frame); 364 pr_err("BUG: KCSAN: %s in %ps / %ps\n", 365 get_bug_type(ai->access_type | other_info->ai.access_type), 366 (void *)(cmp < 0 ? other_frame : this_frame), 367 (void *)(cmp < 0 ? this_frame : other_frame)); 368 } else { 369 pr_err("BUG: KCSAN: %s in %pS\n", get_bug_type(ai->access_type), 370 (void *)this_frame); 371 } 372 373 pr_err("\n"); 374 375 /* Print information about the racing accesses. */ 376 if (other_info) { 377 pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n", 378 get_access_type(other_info->ai.access_type), other_info->ai.ptr, 379 other_info->ai.size, get_thread_desc(other_info->ai.task_pid), 380 other_info->ai.cpu_id); 381 382 /* Print the other thread's stack trace. */ 383 stack_trace_print(other_info->stack_entries + other_skipnr, 384 other_info->num_stack_entries - other_skipnr, 385 0); 386 387 if (IS_ENABLED(CONFIG_KCSAN_VERBOSE)) 388 print_verbose_info(other_info->task); 389 390 pr_err("\n"); 391 pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n", 392 get_access_type(ai->access_type), ai->ptr, ai->size, 393 get_thread_desc(ai->task_pid), ai->cpu_id); 394 } else { 395 pr_err("race at unknown origin, with %s to 0x%px of %zu bytes by %s on cpu %i:\n", 396 get_access_type(ai->access_type), ai->ptr, ai->size, 397 get_thread_desc(ai->task_pid), ai->cpu_id); 398 } 399 /* Print stack trace of this thread. */ 400 stack_trace_print(stack_entries + skipnr, num_stack_entries - skipnr, 401 0); 402 403 if (IS_ENABLED(CONFIG_KCSAN_VERBOSE)) 404 print_verbose_info(current); 405 406 /* Print observed value change */ 407 if (ai->size <= 8) { 408 int hex_len = ai->size * 2; 409 u64 diff = old ^ new; 410 if (mask) 411 diff &= mask; 412 if (diff) { 413 pr_err("\n"); 414 pr_err("value changed from 0x%0*lx to 0x%0*lx\n", 416 pr_err("bits changed 0x%0*lx with mask 0x%0*lx\n", 417 hex_len, diff, hex_len, mask); 418 } 419 } 420 421 /* Print report footer. */ 422 pr_err("\n"); 423 pr_err("Reported by Kernel Concurrency Sanitizer on:\n"); 424 dump_stack_print_info(KERN_DEFAULT); 425 pr_err("==================================================================\n"); 426 427 if (panic_on_warn) 428 panic("panic_on_warn set ...\n"); 429 } 430 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org