From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755977AbbALSry (ORCPT ); Mon, 12 Jan 2015 13:47:54 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:58280 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755155AbbALSac (ORCPT ); Mon, 12 Jan 2015 13:30:32 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Jiri Olsa , Arnaldo Carvalho de Melo , Frederic Weisbecker , Linus Torvalds , Peter Zijlstra , Stephane Eranian , Vince Weaver , "Yan, Zheng" , Ingo Molnar , Luis Henriques Subject: [PATCH 3.16.y-ckt 163/216] perf: Fix events installation during moving group Date: Mon, 12 Jan 2015 18:29:01 +0000 Message-Id: <1421087394-2712-51-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> References: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiri Olsa commit 9fc81d87420d0d3fd62d5e5529972c0ad9eab9cc upstream. We allow PMU driver to change the cpu on which the event should be installed to. This happened in patch: e2d37cd213dc ("perf: Allow the PMU driver to choose the CPU on which to install events") This patch also forces all the group members to follow the currently opened events cpu if the group happened to be moved. This and the change of event->cpu in perf_install_in_context() function introduced in: 0cda4c023132 ("perf: Introduce perf_pmu_migrate_context()") forces group members to change their event->cpu, if the currently-opened-event's PMU changed the cpu and there is a group move. Above behaviour causes problem for breakpoint events, which uses event->cpu to touch cpu specific data for breakpoints accounting. By changing event->cpu, some breakpoints slots were wrongly accounted for given cpu. Vinces's perf fuzzer hit this issue and caused following WARN on my setup: WARNING: CPU: 0 PID: 20214 at arch/x86/kernel/hw_breakpoint.c:119 arch_install_hw_breakpoint+0x142/0x150() Can't find any breakpoint slot [...] This patch changes the group moving code to keep the event's original cpu. Reported-by: Vince Weaver Signed-off-by: Jiri Olsa Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Cc: Yan, Zheng Link: http://lkml.kernel.org/r/1418243031-20367-3-git-send-email-jolsa@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Luis Henriques --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 6bc75223aaa7..cfaeffaefc75 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7329,11 +7329,11 @@ SYSCALL_DEFINE5(perf_event_open, if (move_group) { synchronize_rcu(); - perf_install_in_context(ctx, group_leader, event->cpu); + perf_install_in_context(ctx, group_leader, group_leader->cpu); get_ctx(ctx); list_for_each_entry(sibling, &group_leader->sibling_list, group_entry) { - perf_install_in_context(ctx, sibling, event->cpu); + perf_install_in_context(ctx, sibling, sibling->cpu); get_ctx(ctx); } } -- 2.1.4