Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751329AbdGQGIM (ORCPT ); Mon, 17 Jul 2017 02:08:12 -0400 Received: from muru.com ([72.249.23.125]:54812 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751253AbdGQGIL (ORCPT ); Mon, 17 Jul 2017 02:08:11 -0400 Date: Sun, 16 Jul 2017 23:08:07 -0700 From: Tony Lindgren To: Alex Shi Cc: paulmck@linux.vnet.ibm.com, "Rafael J. Wysocki" , Linux Kernel Mailing List , Linux PM , Linux OMAP Mailing List , Catalin Marinas , Will Deacon Subject: Re: Regression with suspicious RCU usage splats with cpu_pm change Message-ID: <20170717060806.GC10026@atomide.com> References: <20170713070749.GE16509@atomide.com> <20170713124318.GK2393@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 780 Lines: 24 * Alex Shi [170716 16:25]: > I reused the rcu_irq_enter_irqson() from RCU_NONIDLE to avoid this issue. > It works fine. > > Tony, Could you like to give a tested-by if this patch works for you. Yeah that keeps things booting for me with no splats so: Tested-by: Tony Lindgren In general, it seems we're missing the knowledge in Linux kernel of when the entire system is idle. Right now it seems that only cpuidle_coupled knows that? We could probably simplify things by adding some PM state for entire system idle. Then cpuidle code and timer code could use that to test when it's safe to do whatever the SoC needs to do to enter deeper power states. If we already have something like that, please do let me know :) Regards, Tony