From patchwork Mon Apr 4 23:25:56 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 606326 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 3qfMH900LCz9t64; Tue, 5 Apr 2016 18:20:20 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1anMDf-0001AC-Rk; Tue, 05 Apr 2016 08:20:15 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1anDue-0008OL-Kj for kernel-team@lists.ubuntu.com; Mon, 04 Apr 2016 23:28:04 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1anDud-0000B6-R2; Mon, 04 Apr 2016 23:28:04 +0000 Received: from kamal by fourier with local (Exim 4.86_2) (envelope-from ) id 1anDub-0000Lg-4W; Mon, 04 Apr 2016 16:28:01 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.13.y-ckt 32/97] perf/core: Fix perf_sched_count derailment Date: Mon, 4 Apr 2016 16:25:56 -0700 Message-Id: <1459812421-933-33-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1459812421-933-1-git-send-email-kamal@canonical.com> References: <1459812421-933-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 X-Mailman-Approved-At: Tue, 05 Apr 2016 08:20:14 +0000 Cc: Arnaldo Carvalho de Melo , Vince Weaver , Alexander Shishkin , Linus Torvalds , Kamal Mostafa , vince@deater.net, Stephane Eranian , Arnaldo Carvalho de Melo , Peter Zijlstra , Thomas Gleixner , Jiri Olsa , Ingo Molnar X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.13.11-ckt38 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ 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: Kamal Mostafa --- 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 5a90a64..e4a1467 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6786,6 +6786,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, } } + /* symmetric to unaccount_event() in _free_event() */ + account_event(event); + return event; err_pmu: @@ -7091,8 +7094,6 @@ SYSCALL_DEFINE5(perf_event_open, } } - account_event(event); - /* * Special case software events and allow them to be part of * any hardware group. @@ -7299,8 +7300,6 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, goto err; } - account_event(event); - ctx = find_get_context(event->pmu, task, cpu); if (IS_ERR(ctx)) { err = PTR_ERR(ctx);