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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 EB03CC432C0 for ; Tue, 3 Dec 2019 10:07:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ACCA22068E for ; Tue, 3 Dec 2019 10:07:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qdwlRf7d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726055AbfLCKHE (ORCPT ); Tue, 3 Dec 2019 05:07:04 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:45914 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725773AbfLCKHE (ORCPT ); Tue, 3 Dec 2019 05:07:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=XdmrDQOuHXuIfgte9QNr112aIGouu8jBb0/v7TDUy3c=; b=qdwlRf7dDrrc8x2bv9FKsVWbU nuKsl3xeiJt44iVM4jknsTxXDavKW+EpuzQzwua3EHI3/wwYjus78ebrmLKWO5b5yTD1faJ1jrdlq GeCX1nv51AqbemZOr+8WmopZKh4zKEVwdESEZTTvOnaXIYW47wb+LX8bcE20kfoI6rjpjIqoMaKqA Yb1Dfpw5nemL0IvYuNcZeUoEVjm75CMZv/Bc1jB+QHjwWl1Wbcl5OjDTkHH9AQiivO9JDKhDnuHKT iiHoDVpnj3/2YDihOWdvtEgkFWlkpYODDbxDLjd+vipusDDuAkqmKzl1G/+UPKFfleKnSO+VK3Lk9 qnekcf5ZA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ic55B-0005EO-Sg; Tue, 03 Dec 2019 10:07:02 +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 696103006E3; Tue, 3 Dec 2019 11:05:43 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A16232061BAF9; Tue, 3 Dec 2019 11:06:59 +0100 (CET) Date: Tue, 3 Dec 2019 11:06:59 +0100 From: Peter Zijlstra To: Tejun Heo Cc: "Paul E. McKenney" , jiangshanlai@gmail.com, linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner Subject: Re: Workqueues splat due to ending up on wrong CPU Message-ID: <20191203100659.GA2871@hirez.programming.kicks-ass.net> References: <20191125230312.GP2889@paulmck-ThinkPad-P72> <20191126183334.GE2867037@devbig004.ftw2.facebook.com> <20191126220533.GU2889@paulmck-ThinkPad-P72> <20191127155027.GA15170@paulmck-ThinkPad-P72> <20191128161823.GA24667@paulmck-ThinkPad-P72> <20191129155850.GA17002@paulmck-ThinkPad-P72> <20191202015548.GA13391@paulmck-ThinkPad-P72> <20191202201338.GH16681@devbig004.ftw2.facebook.com> <20191203095521.GH2827@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191203095521.GH2827@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 03, 2019 at 10:55:21AM +0100, Peter Zijlstra wrote: > @@ -1100,6 +1099,12 @@ void cpuhp_online_idle(enum cpuhp_state state) > if (state != CPUHP_AP_ONLINE_IDLE) > return; > > + /* > + * Unpark the stopper thread before we start the idle thread; this s/thread/loop/, _this_ is the idle thread :-) > + * ensures the stopper is always available. > + */ > + stop_machine_unpark(smp_processor_id()); > + > st->state = CPUHP_AP_ONLINE_IDLE; > complete_ap_thread(st, true); > }