From: Namhyung Kim <namhyung@xxxxxxxxxx> commit e3265a4386428d3d157d9565bb520aabff8b4bf0 upstream. It was reported that some perf event setup can make fork failed on ARM64. It was the case of a group of mixed hw and sw events and it failed in perf_event_init_task() due to armpmu_event_init(). The ARM PMU code checks if all the events in a group belong to the same PMU except for software events. But it didn't set the event_caps of inherited events and no longer identify them as software events. Therefore the test failed in a child process. A simple reproducer is: $ perf stat -e '{cycles,cs,instructions}' perf bench sched messaging # Running 'sched/messaging' benchmark: perf: fork(): Invalid argument The perf stat was fine but the perf bench failed in fork(). Let's inherit the event caps from the parent. Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20220328200112.457740-1-namhyung@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/events/core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11596,6 +11596,9 @@ perf_event_alloc(struct perf_event_attr event->state = PERF_EVENT_STATE_INACTIVE; + if (parent_event) + event->event_caps = parent_event->event_caps; + if (event->attr.sigtrap) atomic_set(&event->event_limit, 1); Patches currently in stable-queue which might be from namhyung@xxxxxxxxxx are queue-5.15/perf-core-inherit-event_caps.patch queue-5.15/perf-arm-spe-fix-perf-report-mem-mode.patch queue-5.15/perf-session-remap-buf-if-there-is-no-space-for-even.patch