Messages in this thread Patch in this message | | | Subject | Re: [PATCH] perf cgroups: Fix perf_cgroup_switch schedule in warning | From | Peter Zijlstra <> | Date | Tue, 02 Oct 2012 15:46:49 +0200 |
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On Tue, 2012-10-02 at 15:34 +0200, Stephane Eranian wrote: > And adding a comment in cgroup_switch() > > + /* ensure we process each cpuctx only once */ > + if (cpuctx->active_pmu != pmu) > + continue; > --- Subject: perf: Fix perf_cgroup_switch for sw-events From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Tue Oct 02 15:41:23 CEST 2012
Jiri reported that he could trigger the WARN_ON_ONCE() in perf_cgroup_switch() using sw-events. This is because sw-events share a cpuctx with multiple PMUs.
Use the ->unique_pmu pointer to limit the pmu iteration to unique cpuctx instances.
Reported-and-Tested-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- kernel/events/core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -372,6 +372,8 @@ void perf_cgroup_switch(struct task_stru list_for_each_entry_rcu(pmu, &pmus, entry) { cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); + if (cpuctx->unique_pmu != pmu) + continue; /* ensure we process each cpuctx once */ /* * perf_cgroup_events says at least one @@ -395,9 +397,10 @@ void perf_cgroup_switch(struct task_stru if (mode & PERF_CGROUP_SWIN) { WARN_ON_ONCE(cpuctx->cgrp); - /* set cgrp before ctxsw in to - * allow event_filter_match() to not - * have to pass task around + /* + * set cgrp before ctxsw in to allow + * event_filter_match() to not have to pass + * task around */ cpuctx->cgrp = perf_cgroup_from_task(task); cpu_ctx_sched_in(cpuctx, EVENT_ALL, task);
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