tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/wip2 head: fb0089110c5e29151c75028add05458ad2bf8a68 commit: b89bc5672b8331856b35fa6f63117c9832dd7416 [3/5] sched/core: Wait for tasks being pushed away on hotplug config: powerpc-randconfig-r014-20200916 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 9e3842d60351f986d77dfe0a94f76e4fd895f188) 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 powerpc cross compiling tool for clang build # apt-get install binutils-powerpc-linux-gnu git checkout b89bc5672b8331856b35fa6f63117c9832dd7416 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All error/warnings (new ones prefixed by >>): __do_insw ^ arch/powerpc/include/asm/io.h:542:56: 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 kernel/sched/core.c:10: In file included from include/trace/events/sched.h:652: In file included from include/trace/define_trace.h:102: In file included from include/trace/trace_events.h:21: In file included from include/linux/trace_events.h:9: In file included from include/linux/hardirq.h:10: In file included from arch/powerpc/include/asm/hardirq.h:6: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:47:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insl, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:118:1: note: expanded from here __do_insl ^ arch/powerpc/include/asm/io.h:543:56: 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 kernel/sched/core.c:10: In file included from include/trace/events/sched.h:652: In file included from include/trace/define_trace.h:102: In file included from include/trace/trace_events.h:21: In file included from include/linux/trace_events.h:9: In file included from include/linux/hardirq.h:10: In file included from arch/powerpc/include/asm/hardirq.h:6: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:49:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsb, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:120:1: note: expanded from here __do_outsb ^ arch/powerpc/include/asm/io.h:544:58: 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 kernel/sched/core.c:10: In file included from include/trace/events/sched.h:652: In file included from include/trace/define_trace.h:102: In file included from include/trace/trace_events.h:21: In file included from include/linux/trace_events.h:9: In file included from include/linux/hardirq.h:10: In file included from arch/powerpc/include/asm/hardirq.h:6: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:51:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsw, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:122:1: note: expanded from here __do_outsw ^ arch/powerpc/include/asm/io.h:545:58: 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 kernel/sched/core.c:10: In file included from include/trace/events/sched.h:652: In file included from include/trace/define_trace.h:102: In file included from include/trace/trace_events.h:21: In file included from include/linux/trace_events.h:9: In file included from include/linux/hardirq.h:10: In file included from arch/powerpc/include/asm/hardirq.h:6: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:53:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsl, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:124:1: note: expanded from here __do_outsl ^ arch/powerpc/include/asm/io.h:546:58: note: expanded from macro '__do_outsl' #define __do_outsl(p, b, n) writesl((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ kernel/sched/core.c:2380:6: warning: no previous prototype for function 'sched_set_stop_task' [-Wmissing-prototypes] void sched_set_stop_task(int cpu, struct task_struct *stop) ^ kernel/sched/core.c:2380:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void sched_set_stop_task(int cpu, struct task_struct *stop) ^ static rcuwait_wait_event(&rq->hotplug_wait, rq->nr_running == 1, ~~ ^ include/linux/rcuwait.h:59:21: note: expanded from macro 'rcuwait_wait_event' prepare_to_rcuwait(w); \ ^ rcuwait_wait_event(&rq->hotplug_wait, rq->nr_running == 1, ~~ ^ include/linux/rcuwait.h:76:17: note: expanded from macro 'rcuwait_wait_event' finish_rcuwait(w); \ ^ kernel/sched/core.c:4698:35: warning: no previous prototype for function 'schedule_user' [-Wmissing-prototypes] asmlinkage __visible void __sched schedule_user(void) ^ kernel/sched/core.c:4698:22: note: declare 'static' if the function is not intended to be used outside of this translation unit asmlinkage __visible void __sched schedule_user(void) ^ static static inline void balance_hotplug_wait(void) { } ^ include/linux/compiler_types.h:144:23: note: expanded from macro 'inline' #define inline inline __gnu_inline __inline_maybe_unused notrace ^ include/linux/compiler_attributes.h:161:56: note: expanded from macro '__gnu_inline' #define __gnu_inline __attribute__((__gnu_inline__)) ^ kernel/sched/core.c:2597:13: note: previous definition is here static void balance_hotplug_wait(void) ^ static inline void balance_hotplug_wait(void) { } ^ include/linux/compiler_types.h:144:58: note: expanded from macro 'inline' #define inline inline __gnu_inline __inline_maybe_unused notrace ^ include/linux/compiler_types.h:124:34: note: expanded from macro 'notrace' #define notrace __attribute__((__no_instrument_function__)) ^ kernel/sched/core.c:2597:13: note: previous definition is here static void balance_hotplug_wait(void) ^ static inline void balance_hotplug_wait(void) { } ^ kernel/sched/core.c:2597:13: note: previous definition is here static void balance_hotplug_wait(void) ^ kernel/sched/core.c:7055:2: error: implicit declaration of function 'balance_push_set' [-Werror,-Wimplicit-function-declaration] balance_push_set(cpu, false); ^ kernel/sched/core.c:7055:2: note: did you mean 'balance_push'? kernel/sched/core.c:6963:20: note: 'balance_push' declared here static inline bool balance_push(struct rq *rq) ^ kernel/sched/core.c:7104:2: error: implicit declaration of function 'balance_push_set' [-Werror,-Wimplicit-function-declaration] balance_push_set(cpu, true); ^ 16 warnings and 5 errors generated. # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?... git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git git fetch --no-tags peterz-queue sched/wip2 git checkout b89bc5672b8331856b35fa6f63117c9832dd7416 vim +2601 kernel/sched/core.c 2590 2591 /* 2592 * Invoked from a CPUs hotplug control thread after the CPU has been marked 2593 * inactive. All tasks which are not per CPU kernel threads are either 2594 * pushed off this CPU now via balance_push() or placed on a different CPU 2595 * during wakeup. Wait until the CPU is quiescent. 2596 */ 2597 static void balance_hotplug_wait(void) 2598 { 2599 struct rq *rq = this_rq(); 2600 2602 TASK_UNINTERRUPTIBLE); 2603 } 2604 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org