From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S969438AbdEXKZk (ORCPT ); Wed, 24 May 2017 06:25:40 -0400 Received: from terminus.zytor.com ([65.50.211.136]:40529 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S969293AbdEXKXf (ORCPT ); Wed, 24 May 2017 06:23:35 -0400 Date: Wed, 24 May 2017 03:18:56 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: torvalds@linux-foundation.org, mark.rutland@arm.com, xiaolong.ye@intel.com, hpa@zytor.com, rostedt@goodmis.org, tglx@linutronix.de, gregkh@linuxfoundation.org, mingo@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org Reply-To: mingo@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, tglx@linutronix.de, hpa@zytor.com, rostedt@goodmis.org, xiaolong.ye@intel.com, torvalds@linux-foundation.org, mark.rutland@arm.com In-Reply-To: <20170524065202.v25vyu7pvba5mhpd@hirez.programming.kicks-ass.net> References: <20170524065202.v25vyu7pvba5mhpd@hirez.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/clock: Fix early boot preempt assumption in __set_sched_clock_stable() Git-Commit-ID: 45aea321678856687927c53972321ebfab77759a 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: 45aea321678856687927c53972321ebfab77759a Gitweb: http://git.kernel.org/tip/45aea321678856687927c53972321ebfab77759a Author: Peter Zijlstra AuthorDate: Wed, 24 May 2017 08:52:02 +0200 Committer: Ingo Molnar CommitDate: Wed, 24 May 2017 09:10:00 +0200 sched/clock: Fix early boot preempt assumption in __set_sched_clock_stable() The more strict early boot preemption warnings found that __set_sched_clock_stable() was incorrectly assuming we'd still be running on a single CPU: BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 caller is debug_smp_processor_id+0x1c/0x1e CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2-00108-g1c3c5ea #1 Call Trace: dump_stack+0x110/0x192 check_preemption_disabled+0x10c/0x128 ? set_debug_rodata+0x25/0x25 debug_smp_processor_id+0x1c/0x1e sched_clock_init_late+0x27/0x87 [...] Fix it by disabling IRQs. Reported-by: kernel test robot Signed-off-by: Peter Zijlstra (Intel) Acked-by: Thomas Gleixner Cc: Greg Kroah-Hartman Cc: Linus Torvalds Cc: Mark Rutland Cc: Peter Zijlstra Cc: Steven Rostedt Cc: lkp@01.org Cc: tipbuild@zytor.com Link: http://lkml.kernel.org/r/20170524065202.v25vyu7pvba5mhpd@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/sched/clock.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 1a0d389..ca0f8fc 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -133,12 +133,19 @@ static void __scd_stamp(struct sched_clock_data *scd) static void __set_sched_clock_stable(void) { - struct sched_clock_data *scd = this_scd(); + struct sched_clock_data *scd; /* + * Since we're still unstable and the tick is already running, we have + * to disable IRQs in order to get a consistent scd->tick* reading. + */ + local_irq_disable(); + scd = this_scd(); + /* * Attempt to make the (initial) unstable->stable transition continuous. */ __sched_clock_offset = (scd->tick_gtod + __gtod_offset) - (scd->tick_raw); + local_irq_enable(); printk(KERN_INFO "sched_clock: Marking stable (%lld, %lld)->(%lld, %lld)\n", scd->tick_gtod, __gtod_offset,