Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754549AbcDJUMF (ORCPT ); Sun, 10 Apr 2016 16:12:05 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53106 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757379AbcDJS6h (ORCPT ); Sun, 10 Apr 2016 14:58:37 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Shishkin , "Peter Zijlstra (Intel)" , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Stephane Eranian , Thomas Gleixner , Vince Weaver , vince@deater.net, Ingo Molnar Subject: [PATCH 4.4 018/210] perf/core: Fix perf_sched_count derailment Date: Sun, 10 Apr 2016 11:33:59 -0700 Message-Id: <20160410183527.325656436@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160410183526.651820045@linuxfoundation.org> References: <20160410183526.651820045@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2243 Lines: 69 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Shishkin commit 927a5570855836e5d5859a80ce7e91e963545e8f upstream. 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: 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 Signed-off-by: Greg Kroah-Hartman --- kernel/events/core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7979,6 +7979,9 @@ perf_event_alloc(struct perf_event_attr } } + /* symmetric to unaccount_event() in _free_event() */ + account_event(event); + return event; err_per_task: @@ -8342,8 +8345,6 @@ SYSCALL_DEFINE5(perf_event_open, } } - account_event(event); - /* * Special case software events and allow them to be part of * any hardware group. @@ -8626,8 +8627,6 @@ perf_event_create_kernel_counter(struct /* Mark owner so we could distinguish it from user events. */ event->owner = EVENT_OWNER_KERNEL; - account_event(event); - ctx = find_get_context(event->pmu, task, event); if (IS_ERR(ctx)) { err = PTR_ERR(ctx);