From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760072AbcBYIHq (ORCPT ); Thu, 25 Feb 2016 03:07:46 -0500 Received: from torg.zytor.com ([198.137.202.12]:58934 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759862AbcBYIHp (ORCPT ); Thu, 25 Feb 2016 03:07:45 -0500 Date: Thu, 25 Feb 2016 00:07:02 -0800 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, acme@redhat.com, oleg@redhat.com, alexander.shishkin@linux.intel.com, jolsa@redhat.com, tglx@linutronix.de, mingo@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com Reply-To: torvalds@linux-foundation.org, hpa@zytor.com, mingo@kernel.org, jolsa@redhat.com, alexander.shishkin@linux.intel.com, tglx@linutronix.de, oleg@redhat.com, acme@redhat.com, linux-kernel@vger.kernel.org, peterz@infradead.org In-Reply-To: <20160224174948.159242158@infradead.org> References: <20160224174948.159242158@infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf: Fix scaling vs. perf_event_enable_on_exec() Git-Commit-ID: 7fce250915efca0f8f51dddee3ae89bf30d86ca5 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: 7fce250915efca0f8f51dddee3ae89bf30d86ca5 Gitweb: http://git.kernel.org/tip/7fce250915efca0f8f51dddee3ae89bf30d86ca5 Author: Peter Zijlstra AuthorDate: Wed, 24 Feb 2016 18:45:48 +0100 Committer: Ingo Molnar CommitDate: Thu, 25 Feb 2016 08:43:34 +0100 perf: Fix scaling vs. perf_event_enable_on_exec() The recent commit 3e349507d12d ("perf: Fix perf_enable_on_exec() event scheduling") caused this by moving task_ctx_sched_out() from before __perf_event_mask_enable() to after it. The overlooked consequence of that change is that task_ctx_sched_out() would update the ctx time fields, and now __perf_event_mask_enable() uses stale time. In order to fix this, explicitly stop our context's time before enabling the event(s). Reported-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dvyukov@google.com Cc: eranian@google.com Cc: panand@redhat.com Cc: sasha.levin@oracle.com Cc: vince@deater.net Fixes: 3e349507d12d ("perf: Fix perf_enable_on_exec() event scheduling") Link: http://lkml.kernel.org/r/20160224174948.159242158@infradead.org Signed-off-by: Ingo Molnar --- kernel/events/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 75bde93..d003088 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3143,6 +3143,7 @@ static void perf_event_enable_on_exec(int ctxn) cpuctx = __get_cpu_context(ctx); perf_ctx_lock(cpuctx, ctx); + ctx_sched_out(ctx, cpuctx, EVENT_TIME); list_for_each_entry(event, &ctx->event_list, event_entry) enabled |= event_enable_on_exec(event, ctx);