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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 37D54C282CE for ; Tue, 4 Jun 2019 12:07:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 08DB4249F0 for ; Tue, 4 Jun 2019 12:07:07 +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="FwO2bWK5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727567AbfFDMHG (ORCPT ); Tue, 4 Jun 2019 08:07:06 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38170 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727358AbfFDMHF (ORCPT ); Tue, 4 Jun 2019 08:07:05 -0400 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=syCKIAxBHgkuMWXLTEQ3r1RG7kSirXm5ulIaSV56KSI=; b=FwO2bWK5E7fMVtBY8ox3opJRm TDa/KgZBTFoCzROgRwfPwHZKdfp7gdDnr7owQWe7w465nDekukdOk/yt9c5z6WqddqI85POtymGTi xSauj2+vi3yLM69dppRZPmumFsUh7OSpIPCWWmV+erylP4AHU37PQ1fU2lHINquEV5HmhkKBz6A3O AuG870/KneaJlBKPJSL4IvnMaoVh5icti+wL3ZTvDxgpbVa5vFjRpAe6rj+H5CPr4GNn31+7eqA5j ITmJ2+tGoHt+cvtBly8MeoJ/iR65pTs2lsTNEwWFz6awbBQugtx/Bm+2OtL2xVu3EB6aN+qNNVXJ9 qb2dvfOzg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hY8DV-0001QW-Sl; Tue, 04 Jun 2019 12:07:02 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id F2A7020114D93; Tue, 4 Jun 2019 14:06:59 +0200 (CEST) Date: Tue, 4 Jun 2019 14:06:59 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: tglx@linutronix.de, mingo@kernel.org, jpoimboe@redhat.com, mojha@codeaurora.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH HACK RFC] cpu: Prevent late-arriving interrupts from disrupting offline Message-ID: <20190604120659.GC3419@hirez.programming.kicks-ass.net> References: <20190602011253.GA6167@linux.ibm.com> <20190603083848.GB3436@hirez.programming.kicks-ass.net> <20190604081435.GQ28207@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190604081435.GQ28207@linux.ibm.com> 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, Jun 04, 2019 at 01:14:35AM -0700, Paul E. McKenney wrote: > On Mon, Jun 03, 2019 at 10:38:48AM +0200, Peter Zijlstra wrote: > > And then there's powerpc which for some obscure reason thinks it needs > > to enable preemption when dying ?! pseries_cpu_die() actually calls > > msleep() ?!?! > > Isn't pseries_cpu_die() invoked via the smp_ops->cpu_die() function > pointer, whch is invoked from __cpu_die() in arch/powerpc/kernel/smp.c? > Then, if I am reading the code correctly, __cpu_die() is invoked from > takedown_cpu(), which is invoked not from the dying CPU but rather from > a surviving CPU. Or am I misreading the code? Argh.. arch_cpu_idle_dead() -> cpu_die() -> ppc_md.cpu_die() which is _NOT_ smp_ops.cpu_die() this one ends in pseries_mach_cpu_die()