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Message-Id: <20130929190758.047604598@linuxfoundation.org>
Date: Sun, 29 Sep 2013 12:26:52 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...nel.org>, Li Zefan <lizefan@...wei.com>
Subject: [ 13/17] perf: Fix perf_cgroup_switch for sw-events
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
commit 95cf59ea72331d0093010543b8951bb43f262cac upstream.
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@...hat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/n/tip-so7wi2zf3jjzrwcutm2mkz0j@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Li Zefan <lizefan@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
kernel/events/core.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -342,6 +342,8 @@ 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_pmu_disable(cpuctx->ctx.pmu);
@@ -365,9 +367,10 @@ 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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