Hi Daniel, Thank you for the patch! Yet something to improve: [auto build test ERROR on bpf-next/master] url: https://github.com/0day-ci/linux/commits/Daniel-Xu/perf-core-Add-PERF_FORMAT_LOST-read_format/20190917-213515 base: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git master config: i386-randconfig-e003-201937 (attached as .config) compiler: gcc-7 (Debian 7.4.0-11) 7.4.0 reproduce: # save the attached .config to linux build tree make ARCH=i386 If you fix the issue, kindly add following tag Reported-by: kbuild test robot All errors (new ones prefixed by >>): kernel/events/core.c: In function 'perf_event_lost': >> kernel/events/core.c:4753:11: error: implicit declaration of function 'perf_kprobe_missed'; did you mean 'perf_uprobe_init'? [-Werror=implicit-function-declaration] lost += perf_kprobe_missed(event); ^~~~~~~~~~~~~~~~~~ perf_uprobe_init cc1: some warnings being treated as errors vim +4753 kernel/events/core.c 4739 4740 static struct pmu perf_kprobe; 4741 static u64 perf_event_lost(struct perf_event *event) 4742 { 4743 struct ring_buffer *rb; 4744 u64 lost = 0; 4745 4746 rcu_read_lock(); 4747 rb = rcu_dereference(event->rb); 4748 if (likely(!!rb)) 4749 lost += local_read(&rb->lost); 4750 rcu_read_unlock(); 4751 4752 if (event->attr.type == perf_kprobe.type) > 4753 lost += perf_kprobe_missed(event); 4754 4755 return lost; 4756 } 4757 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation