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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 07A75C43331 for ; Sat, 16 Jan 2021 17:13:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA6312388E for ; Sat, 16 Jan 2021 17:13:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728915AbhAPRNo (ORCPT ); Sat, 16 Jan 2021 12:13:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727898AbhAPRKf (ORCPT ); Sat, 16 Jan 2021 12:10:35 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 68E6CC061345 for ; Sat, 16 Jan 2021 07:27:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=vNVmJZrKuDj2vCmvC6xmw3IOo/UXqLVwa5kqiwmHnOM=; b=WBecyrpweeNtImZCWcy824UlHO r1opbQjX8uSRffKDuKTa58rlFLwBTE9fUcUQeMBD8w2zqSBYl4kxBK8mtHFFOQAJy5qCQFuVe623Z p2YX2bI7hnr3iCy6JOJES5IdfKU1Dqlej21iCD0DozrbN3uzKVPyDNT1ihi945fNZ/29JXMM8dPuy NhSBLY/sS3Hl/d8OlYMTpwpVsmTlmII7ahrBlLAAXFJVkeMTm7xv+lKhblUCwJYtF4UxumFXuZoVZ oFXWqubfrovuffr+HGIN6R5Jh1k985JT4N98o//4UhV/6LbthKIeVAVVgZ1bOc5lSO1l2vzimhybG wAUfUNJA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1l0nTj-0005vW-R8; Sat, 16 Jan 2021 15:27:04 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 70B423010CF; Sat, 16 Jan 2021 16:27:02 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 619D7202A3F5A; Sat, 16 Jan 2021 16:27:02 +0100 (CET) Date: Sat, 16 Jan 2021 16:27:02 +0100 From: Peter Zijlstra To: mingo@kernel.org, tglx@linutronix.de Cc: linux-kernel@vger.kernel.org, jiangshanlai@gmail.com, valentin.schneider@arm.com, cai@redhat.com, vincent.donnefort@arm.com, decui@microsoft.com, paulmck@kernel.org, vincent.guittot@linaro.org, rostedt@goodmis.org, tj@kernel.org Subject: Re: [PATCH 3/8] sched: Dont run cpu-online with balance_push() enabled Message-ID: References: <20210116113033.608340773@infradead.org> <20210116113919.760767084@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210116113919.760767084@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 16, 2021 at 12:30:36PM +0100, Peter Zijlstra wrote: > @@ -7608,6 +7614,12 @@ int sched_cpu_dying(unsigned int cpu) > } > rq_unlock_irqrestore(rq, &rf); > > + /* > + * Should really be after we clear cpu_online(), but we're in > + * stop_machine(), so it all works. > + */ > + balance_push_set(cpu, false); Looking at the RCU thing just now made me realize we run all the DYING notifiers with cpu_online() already false, so the above comment is wrong and ordering in fact perfect.