Messages in this thread |  | | Date | Mon, 28 Aug 2017 21:23:07 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 02/10] perf: Fix leader for removed sibling event in perf_group_detach |
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On Thu, Aug 24, 2017 at 06:27:29PM +0200, Jiri Olsa wrote: > Mark reported warning in x86_perf_event_update caused > by reading unscheduled leader of an event that was > already removed from the group. > > As he pointed out we don't properly reset event's leader > once it's been detached from the group and he posted the > attached fix. > > [1] https://marc.info/?l=linux-kernel&m=150238662928203&w=2 > > Originally-From: Mark Rutland <mark.rutland@arm.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > kernel/events/core.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index d704e23914bf..30e30e94ea32 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -1727,6 +1727,7 @@ static void perf_group_detach(struct perf_event *event) > if (event->group_leader != event) { > list_del_init(&event->group_entry); > event->group_leader->nr_siblings--; > + event->group_leader = event; > goto out; > }
No, I think this breaks other things... but I again forgot what. The original issue he reported is fixed by patch:
2bcb88eb04d3 ("perf/core: fix group {cpu,task} validation")
Also by Mark.
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