Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753920Ab2JBNrD (ORCPT ); Tue, 2 Oct 2012 09:47:03 -0400 Received: from casper.infradead.org ([85.118.1.10]:58158 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753369Ab2JBNrB convert rfc822-to-8bit (ORCPT ); Tue, 2 Oct 2012 09:47:01 -0400 Message-ID: <1349185609.7780.34.camel@twins> Subject: Re: [PATCH] perf cgroups: Fix perf_cgroup_switch schedule in warning From: Peter Zijlstra To: Stephane Eranian Cc: Jiri Olsa , LKML , Frederic Weisbecker , Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo Date: Tue, 02 Oct 2012 15:46:49 +0200 In-Reply-To: References: <20121002114218.GA5891@krava.brq.redhat.com> <1349178781.7780.29.camel@twins> <20121002123921.GB6379@krava.brq.redhat.com> <1349183446.7780.32.camel@twins> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1905 Lines: 56 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 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 Signed-off-by: Peter Zijlstra --- 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/