From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 502E8C432C1 for ; Tue, 24 Sep 2019 11:22:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F66A20872 for ; Tue, 24 Sep 2019 11:22:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440810AbfIXLWA (ORCPT ); Tue, 24 Sep 2019 07:22:00 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:33667 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389615AbfIXLWA (ORCPT ); Tue, 24 Sep 2019 07:22:00 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1iCitH-0004qN-P8; Tue, 24 Sep 2019 13:21:55 +0200 Date: Tue, 24 Sep 2019 13:21:55 +0200 From: Sebastian Andrzej Siewior To: Scott Wood Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, "Paul E . McKenney" , Joel Fernandes , Thomas Gleixner , Steven Rostedt , Peter Zijlstra , Juri Lelli , Clark Williams Subject: Re: [PATCH RT v3 3/5] sched: migrate_dis/enable: Use rt_invol_sleep Message-ID: <20190924112155.rxeyksetgqmer3pg@linutronix.de> References: <20190911165729.11178-1-swood@redhat.com> <20190911165729.11178-4-swood@redhat.com> <20190917075943.qsaakyent4dxjkq4@linutronix.de> <779eddcc937941e65659a11b1867c6623a2c8890.camel@redhat.com> <404575720cf24765e66020f15ce75352f08a0ddb.camel@redhat.com> <20190923175233.yub32stn3xcwkaml@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190923175233.yub32stn3xcwkaml@linutronix.de> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-09-23 19:52:33 [+0200], To Scott Wood wrote: I made dis: diff --git a/kernel/cpu.c b/kernel/cpu.c index 885a195dfbe02..25afa2bb1a2cf 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -308,7 +308,9 @@ void pin_current_cpu(void) preempt_lazy_enable(); preempt_enable(); + sleeping_lock_inc(); __read_rt_lock(cpuhp_pin); + sleeping_lock_dec(); preempt_disable(); preempt_lazy_disable(); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e1bdd7f9be054..63a6420d01053 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7388,6 +7388,7 @@ void migrate_enable(void) WARN_ON(smp_processor_id() != task_cpu(p)); if (!cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) { + struct task_struct *self = current; const struct cpumask *cpu_valid_mask = cpu_active_mask; struct migration_arg arg; unsigned int dest_cpu; @@ -7405,7 +7406,21 @@ void migrate_enable(void) unpin_current_cpu(); preempt_lazy_enable(); preempt_enable(); + rt_invol_sleep_inc(); + + raw_spin_lock_irq(&self->pi_lock); + self->saved_state = self->state; + __set_current_state_no_track(TASK_RUNNING); + raw_spin_unlock_irq(&self->pi_lock); + stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); + + raw_spin_lock_irq(&self->pi_lock); + __set_current_state_no_track(self->saved_state); + self->saved_state = TASK_RUNNING; + raw_spin_unlock_irq(&self->pi_lock); + + rt_invol_sleep_dec(); return; } } I think we need to preserve the current state, otherwise we will lose anything != TASK_RUNNING here. So the spin_lock() would preserve it while waiting but the migrate_enable() will lose it if it needs to change the CPU at the end. I will try to prepare all commits for the next release before I release so you can have a look first and yell if needed. > > -Scott Sebastian