From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753954AbcCHNPq (ORCPT ); Tue, 8 Mar 2016 08:15:46 -0500 Received: from torg.zytor.com ([198.137.202.12]:51706 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753854AbcCHNPh (ORCPT ); Tue, 8 Mar 2016 08:15:37 -0500 Date: Tue, 8 Mar 2016 05:14:55 -0800 From: tip-bot for Alexander Shishkin Message-ID: Cc: hpa@zytor.com, torvalds@linux-foundation.org, acme@redhat.com, peterz@infradead.org, jolsa@redhat.com, stable@vger.kernel.org, vincent.weaver@maine.edu, mingo@kernel.org, eranian@google.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, alexander.shishkin@linux.intel.com, acme@infradead.org Reply-To: mingo@kernel.org, eranian@google.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, alexander.shishkin@linux.intel.com, acme@infradead.org, hpa@zytor.com, peterz@infradead.org, torvalds@linux-foundation.org, acme@redhat.com, jolsa@redhat.com, stable@vger.kernel.org, vincent.weaver@maine.edu In-Reply-To: <1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com> References: <1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf/core: Fix perf_sched_count derailment Git-Commit-ID: 927a5570855836e5d5859a80ce7e91e963545e8f X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 927a5570855836e5d5859a80ce7e91e963545e8f Gitweb: http://git.kernel.org/tip/927a5570855836e5d5859a80ce7e91e963545e8f Author: Alexander Shishkin AuthorDate: Wed, 2 Mar 2016 13:24:14 +0200 Committer: Ingo Molnar CommitDate: Tue, 8 Mar 2016 12:18:31 +0100 perf/core: Fix perf_sched_count derailment The error path in perf_event_open() is such that asking for a sampling event on a PMU that doesn't generate interrupts will end up in dropping the perf_sched_count even though it hasn't been incremented for this event yet. Given a sufficient amount of these calls, we'll end up disabling scheduler's jump label even though we'd still have active events in the system, thereby facilitating the arrival of the infernal regions upon us. I'm fixing this by moving account_event() inside perf_event_alloc(). Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: vince@deater.net Link: http://lkml.kernel.org/r/1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 5dcc0bd..b723149 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8000,6 +8000,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, } } + /* symmetric to unaccount_event() in _free_event() */ + account_event(event); + return event; err_per_task: @@ -8363,8 +8366,6 @@ SYSCALL_DEFINE5(perf_event_open, } } - account_event(event); - /* * Special case software events and allow them to be part of * any hardware group. @@ -8661,8 +8662,6 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, /* Mark owner so we could distinguish it from user events. */ event->owner = TASK_TOMBSTONE; - account_event(event); - ctx = find_get_context(event->pmu, task, event); if (IS_ERR(ctx)) { err = PTR_ERR(ctx);