tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/core head: a918097a296b40b4e4f7a75edf4380a293b84eb5 commit: a918097a296b40b4e4f7a75edf4380a293b84eb5 [10/10] perf: Fix task context PMU for Hetero config: x86_64-randconfig-a002-20210622 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project b3634d3e88b7f26534a5057bff182b7dced584fc) 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/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 perf/core git checkout a918097a296b40b4e4f7a75edf4380a293b84eb5 # 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 >>): pmu = ctx->pmu = cpuctx->ctx.pmu; ^~~~~~ kernel/events/core.c:3824:33: note: initialize the variable 'cpuctx' to silence this warning struct perf_cpu_context *cpuctx; ^ = NULL kernel/events/core.c:1097:1: warning: unused function 'perf_cgroup_switch' [-Wunused-function] perf_cgroup_switch(struct task_struct *task, struct task_struct *next) ^ 2 warnings generated. vim +/cpuctx +3831 kernel/events/core.c 3820 3821 static void perf_event_context_sched_in(struct perf_event_context *ctx, 3822 struct task_struct *task) 3823 { 3824 struct perf_cpu_context *cpuctx; 3825 struct pmu *pmu; 3826 3827 /* 3828 * HACK: for HETEROGENEOUS the task context might have switched to a 3829 * different PMU, force (re)set the context, 3830 */ 3832 3833 cpuctx = __get_cpu_context(ctx); 3834 if (cpuctx->task_ctx == ctx) { 3835 if (cpuctx->sched_cb_usage) 3836 __perf_pmu_sched_task(cpuctx, true); 3837 return; 3838 } 3839 3840 perf_ctx_lock(cpuctx, ctx); 3841 /* 3842 * We must check ctx->nr_events while holding ctx->lock, such 3843 * that we serialize against perf_install_in_context(). 3844 */ 3845 if (!ctx->nr_events) 3846 goto unlock; 3847 3848 perf_pmu_disable(pmu); 3849 /* 3850 * We want to keep the following priority order: 3851 * cpu pinned (that don't need to move), task pinned, 3852 * cpu flexible, task flexible. 3853 * 3854 * However, if task's ctx is not carrying any pinned 3855 * events, no need to flip the cpuctx's events around. 3856 */ 3857 if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree)) 3858 cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); 3859 perf_event_sched_in(cpuctx, ctx, task); 3860 3861 if (cpuctx->sched_cb_usage && pmu->sched_task) 3862 pmu->sched_task(cpuctx->task_ctx, true); 3863 3864 perf_pmu_enable(pmu); 3865 3866 unlock: 3867 perf_ctx_unlock(cpuctx, ctx); 3868 } 3869 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org