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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33926EDEC52 for ; Wed, 13 Sep 2023 13:53:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232734AbjIMNxS (ORCPT ); Wed, 13 Sep 2023 09:53:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231433AbjIMNxS (ORCPT ); Wed, 13 Sep 2023 09:53:18 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09B7A19B6; Wed, 13 Sep 2023 06:53:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=HBGkdRgqPXI4bHcmCrKt82K03JWpt+6ZAQAiRZJ7acE=; b=Mi4UuSRD2ivRV5Q2hqAggIYI1z k3GbBEZ14lnReEsSNnZm9fAYEZ+KIzLh80yw1vsU9aUJjqKk4R0S90mQ5zOT9hXmfJwZNiVkHaTol Shy0DdygOKgcpxDo4AueJUNmxDm2peQ4gGUNLYtX5qjvM0MB/dedxiUR9U+kjNjbXbM0mikAmF/ut JB1BgzgQHXcMH2DKXmbEb0vdOpetaicthLGORK2lwmY3EJNlXHP2iPi7jcAagXpl35oZcoRom77yv y4XWVjuid309Cn25/5+rVLJa3eWYC/ZmzEHxhOOtHxg0IRYyXXdyJXyWOdHCrl8J2/qhJi0LATG5t V1p/5q6Q==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qgQIQ-00EDF7-Jd; Wed, 13 Sep 2023 13:52:46 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 466A9300348; Wed, 13 Sep 2023 15:52:46 +0200 (CEST) Date: Wed, 13 Sep 2023 15:52:46 +0200 From: Peter Zijlstra To: "Liam R. Howlett" Cc: Andrew Morton , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Geert Uytterhoeven , "Paul E. McKenney" , Christophe Leroy , Andreas Schwab , Matthew Wilcox , Peng Zhang , Ingo Molnar , Juri Lelli , Vincent Guittot , "Mike Rapoport (IBM)" , Vlastimil Babka Subject: Re: [PATCH] init/main: Clear boot task idle flag Message-ID: <20230913135246.GH692@noisy.programming.kicks-ass.net> References: <20230913005647.1534747-1-Liam.Howlett@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230913005647.1534747-1-Liam.Howlett@oracle.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Sep 12, 2023 at 08:56:47PM -0400, Liam R. Howlett wrote: > diff --git a/init/main.c b/init/main.c > index ad920fac325c..f74772acf612 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -696,7 +696,7 @@ noinline void __ref __noreturn rest_init(void) > */ > rcu_read_lock(); > tsk = find_task_by_pid_ns(pid, &init_pid_ns); > - tsk->flags |= PF_NO_SETAFFINITY; > + tsk->flags |= PF_NO_SETAFFINITY | PF_IDLE; > set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id())); > rcu_read_unlock(); > Hmm, isn't that pid-1 you're setting PF_IDLE on? The task becoming idle is 'current' at this point, see the cpu_startup_entry() call below. Would not something like so be the right thing? diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2299a5cfbfb9..802551e0009b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9269,7 +9269,7 @@ void __init init_idle(struct task_struct *idle, int cpu) * PF_KTHREAD should already be set at this point; regardless, make it * look like a proper per-CPU kthread. */ - idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY; + idle->flags |= PF_KTHREAD | PF_NO_SETAFFINITY; kthread_set_per_cpu(idle, cpu); #ifdef CONFIG_SMP diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 342f58a329f5..5007b25c5bc6 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -373,6 +373,7 @@ EXPORT_SYMBOL_GPL(play_idle_precise); void cpu_startup_entry(enum cpuhp_state state) { + current->flags |= PF_IDLE; arch_cpu_idle_prepare(); cpuhp_online_idle(state); while (1)