From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753451AbdEPSzC (ORCPT ); Tue, 16 May 2017 14:55:02 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:41329 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753107AbdEPSwz (ORCPT ); Tue, 16 May 2017 14:52:55 -0400 Message-Id: <20170516184736.272225698@linutronix.de> User-Agent: quilt/0.63-1 Date: Tue, 16 May 2017 20:42:48 +0200 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Ingo Molnar , Steven Rostedt , Mark Rutland , Greg Kroah-Hartman Subject: [patch V2 17/17] sched: Enable might_sleep() and smp_processor_id() checks early References: <20170516184231.564888231@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=sched--Enable-might_sleep---checks-early.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org might_sleep() and smp_processor_id() checks are enabled after the boot process is done. That hides bugs in the smp bringup and driver initialization code. Enable it right when the scheduler starts working, i.e. when init task and kthreadd have been created and right before the idle task enables preemption. Signed-off-by: Thomas Gleixner --- init/main.c | 10 ++++++++++ kernel/sched/core.c | 4 +++- lib/smp_processor_id.c | 2 +- 3 files changed, 14 insertions(+), 2 deletions(-) --- a/init/main.c +++ b/init/main.c @@ -414,6 +414,16 @@ static noinline void __ref rest_init(voi rcu_read_lock(); kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns); rcu_read_unlock(); + + /* + * Enable might_sleep() and smp_processor_id() checks. + * They cannot be enabled earlier because with CONFIG_PRREMPT=y + * kernel_thread() would trigger might_sleep() splats. With + * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled + * already, but it's stuck on the kthreadd_done completion. + */ + system_state = SYSTEM_SCHEDULING; + complete(&kthreadd_done); /* --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6226,8 +6226,10 @@ void ___might_sleep(const char *file, in if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && !is_idle_task(current)) || - system_state != SYSTEM_RUNNING || oops_in_progress) + system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING || + oops_in_progress) return; + if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) return; prev_jiffy = jiffies; --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -28,7 +28,7 @@ notrace static unsigned int check_preemp /* * It is valid to assume CPU-locality during early bootup: */ - if (system_state != SYSTEM_RUNNING) + if (system_state < SYSTEM_SCHEDULING) goto out; /*