4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhou Chengming <zhouchengming1@xxxxxxxxxx> [ Upstream commit 4e71de7986386d5fd3765458f27d612931f27f5e ] The CPU hotplug function intel_pmu_cpu_starting() sets cpu_hw_events.excl_thread_id unconditionally to 1 when the shared exclusive counters data structure is already availabe for the sibling thread. This works during the boot process because the first sibling gets threadid 0 assigned and the second sibling which shares the data structure gets 1. But when the first thread of the core is offlined and onlined again it shares the data structure with the second thread and gets exclusive thread id 1 assigned as well. Prevent this by checking the threadid of the already online thread. [ tglx: Rewrote changelog ] Signed-off-by: Zhou Chengming <zhouchengming1@xxxxxxxxxx> Cc: NuoHan Qiao <qiaonuohan@xxxxxxxxxx> Cc: ak@xxxxxxxxxxxxxxx Cc: peterz@xxxxxxxxxxxxx Cc: kan.liang@xxxxxxxxx Cc: dave.hansen@xxxxxxxxxxxxxxx Cc: eranian@xxxxxxxxxx Cc: qiaonuohan@xxxxxxxxxx Cc: davidcc@xxxxxxxxxx Cc: guohanjun@xxxxxxxxxx Link: http://lkml.kernel.org/r/1484536871-3131-1-git-send-email-zhouchengming1@xxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/events/intel/core.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3164,13 +3164,16 @@ static void intel_pmu_cpu_starting(int c if (x86_pmu.flags & PMU_FL_EXCL_CNTRS) { for_each_cpu(i, topology_sibling_cpumask(cpu)) { + struct cpu_hw_events *sibling; struct intel_excl_cntrs *c; - c = per_cpu(cpu_hw_events, i).excl_cntrs; + sibling = &per_cpu(cpu_hw_events, i); + c = sibling->excl_cntrs; if (c && c->core_id == core_id) { cpuc->kfree_on_online[1] = cpuc->excl_cntrs; cpuc->excl_cntrs = c; - cpuc->excl_thread_id = 1; + if (!sibling->excl_thread_id) + cpuc->excl_thread_id = 1; break; } }