tree: https://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git rcu/nocb-toggle-v4 head: 579e15efa48fb6fc4ecf14961804051f385807fe commit: 579e15efa48fb6fc4ecf14961804051f385807fe [19/19] rcu/nocb: Detect unsafe checks for offloaded rdp config: c6x-randconfig-r022-20201113 (attached as .config) compiler: c6x-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/frederic/linux-dynticks.g... git remote add dynticks https://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git git fetch --no-tags dynticks rcu/nocb-toggle-v4 git checkout 579e15efa48fb6fc4ecf14961804051f385807fe # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=c6x If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/linux/rcupdate_wait.h:9, from kernel/rcu/tree.c:25: kernel/rcu/tree_plugin.h: In function 'rcu_rdp_is_offloaded': 71 | (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_held()) || | ^~~~~~~~~~~~~~~~~~~~ include/linux/rcupdate.h:335:52: note: in definition of macro 'RCU_LOCKDEP_WARN' 335 | #define RCU_LOCKDEP_WARN(c, s) do { } while (0 && (c)) | ^ cc1: some warnings being treated as errors vim +71 kernel/rcu/tree_plugin.h 57 58 static bool rcu_rdp_is_offloaded(struct rcu_data *rdp) 59 { 60 /* 61 * In order to read the offloaded state of an rdp is a safe 62 * and stable way and prevent from its value to be changed 63 * under us, we must either hold the barrier mutex, the cpu 64 * hotplug lock (read or write) or the nocb lock. Local 65 * non-preemptible reads are also safe. NOCB kthreads and 66 * timers have their own means of synchronization against the 67 * offloaded state updaters. 68 */ 69 RCU_LOCKDEP_WARN( 70 !(lockdep_is_held(&rcu_state.barrier_mutex) || 72 rcu_lockdep_is_held_nocb(rdp) || 73 (rdp == this_cpu_ptr(&rcu_data) && 74 !(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())) || 75 rcu_current_is_nocb_kthread(rdp) || 76 rcu_running_nocb_timer(rdp)), 77 "Unsafe read of RCU_NOCB offloaded state" 78 ); 79 80 return rcu_segcblist_is_offloaded(&rdp->cblist); 81 } 82 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org