Hi Peter, [FYI, it's a private test report for your RFC patch.] [auto build test ERROR on next-20200429] [cannot apply to tip/sched/core tip/perf/core linus/master linux/master v5.7-rc3 v5.7-rc2 v5.7-rc1 v5.7-rc3] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Peter-Zijlstra/Generic-RB-tree-h... base: 861978d1331b7e988e0295a2275c669c767fa3f1 config: arm64-randconfig-a001-20200429 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project f30416fdde922eaa655934e050026930fefbd260) reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install arm64 cross compiling tool for clang build # apt-get install binutils-aarch64-linux-gnu # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): if (!right->cgroup) { ^~~~~~ cgrp include/linux/perf_event.h:758:23: note: 'cgrp' declared here struct perf_cgroup *cgrp; /* cgroup event is attach to */ ^ if (cgroup_id(left_cgroup) < cgroup_id(right_cgroup)) ^~~~~~~~~~~ include/linux/cgroup.h:310:44: note: passing argument to parameter 'cgrp' here static inline u64 cgroup_id(struct cgroup *cgrp) ^ 2 errors generated. vim +1603 kernel/events/core.c 1575 1576 /* 1577 * Compare function for event groups; 1578 * 1579 * Implements complex key that first sorts by CPU and then by virtual index 1580 * which provides ordering when rotating groups for the same CPU. 1581 */ 1582 static __always_inline int 1583 perf_event_groups_cmp(const int left_cpu, const struct cgroup *left_cgroup, 1584 const u64 left_group_index, const struct perf_event *right) 1585 { 1586 if (left_cpu < right->cpu) 1587 return -1; 1588 if (left_cpu > right->cpu) 1589 return 1; 1590 1591 #ifdef CONFIG_CGROUP_PERF 1592 { 1593 struct cgroup *right_cgroup = right->cgrp ? right->cgrp->css.cgroup : NULL; 1594 1595 if (left_cgroup != right_cgroup) { 1596 if (!left_cgroup) { 1597 /* 1598 * Left has no cgroup but right does, no cgroups come 1599 * first. 1600 */ 1601 return -1; 1602 } 1604 /* 1605 * Right has no cgroup but left does, no cgroups come 1606 * first. 1607 */ 1608 return 1; 1609 } 1610 /* Two dissimilar cgroups, order by id. */ 1612 return -1; 1613 1614 return 1; 1615 } 1616 } 1617 #endif 1618 1619 if (left_group_index < right->group_index) 1620 return -1; 1621 if (left_group_index > right->group_index) 1622 return 1; 1623 1624 return 0; 1625 } 1626 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org