From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752173AbcJKXcy (ORCPT ); Tue, 11 Oct 2016 19:32:54 -0400 Received: from mail-pf0-f182.google.com ([209.85.192.182]:32986 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751821AbcJKXcx (ORCPT ); Tue, 11 Oct 2016 19:32:53 -0400 From: David Carrillo-Cisneros To: linux-kernel@vger.kernel.org Cc: "x86@kernel.org" , Ingo Molnar , Thomas Gleixner , Andi Kleen , Kan Liang , Peter Zijlstra , Vegard Nossum , Paul Turner , Stephane Eranian , David Carrillo-Cisneros Subject: [PATCH] perf/core: do not set cpuctx->cgrp for unscheduled cgroups Date: Tue, 11 Oct 2016 16:27:33 -0700 Message-Id: <1476228453-63474-1-git-send-email-davidcc@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit db4a835601b7 ("perf/core: Set cgroup in CPU contexts for new cgroup events") fails to verify that event->cgrp is actually the scheduled cgroup in a CPU before setting cpuctx->cgrp. This patch fixes that. The bug only impacts the first cgroup that is created in a CPU. Now that there is a different path for scheduled and unscheduled cgroups, add a warning to catch when cpuctx->cgrp is still set after the last cgroup event has been unsheduled. Reviewed-by: Stephane Eranian Signed-off-by: David Carrillo-Cisneros --- kernel/events/core.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 7c0d263..62f70a3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -902,6 +902,17 @@ list_update_cgroup_event(struct perf_event *event, * this will always be called from the right CPU. */ cpuctx = __get_cpu_context(ctx); + + /* Only set/clear cpuctx->cgrp if current task uses event->cgrp. */ + if (perf_cgroup_from_task(current, ctx) != event->cgrp) { + /* + * We are removing the last cpu event in this context. + * If that event is not active in this cpu, cpuctx->cgrp + * should've been cleared by perf_cgroup_switch. + */ + WARN_ON_ONCE(!add && cpuctx->cgrp); + return; + } cpuctx->cgrp = add ? event->cgrp : NULL; } -- 2.8.0.rc3.226.g39d4020