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.zijls...@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 <jo...@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijls...@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);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
