From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757580AbcGZSQ4 (ORCPT ); Tue, 26 Jul 2016 14:16:56 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:8405 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751453AbcGZSQy (ORCPT ); Tue, 26 Jul 2016 14:16:54 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Tue, 26 Jul 2016 11:14:12 -0700 Subject: Re: [patch 61/66] timers: Convert to hotplug state machine To: References: <20160711122450.923603742@linutronix.de> <20160711122535.775201614@linutronix.de> <7d37714e-b072-ee90-f14f-364f4fd01f0d@nvidia.com> <20160726154227.GC23707@linutronix.de> CC: Anna-Maria Gleixner , LKML , Peter Zijlstra , "Ingo Molnar" , Sebastian Andrzej Siewior , "linux-tegra@vger.kernel.org" , Thomas Gleixner From: Jon Hunter Message-ID: Date: Tue, 26 Jul 2016 19:16:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160726154227.GC23707@linutronix.de> X-Originating-IP: [10.26.11.53] X-ClientProxiedBy: UKMAIL101.nvidia.com (10.26.138.13) To UKMAIL101.nvidia.com (10.26.138.13) Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Richard, On 26/07/16 16:42, rcochran@linutronix.de wrote: > Jon, > > On Mon, Jul 25, 2016 at 03:56:48PM +0100, Jon Hunter wrote: >>> When tearing down, call timers_dead_cpu before notify_dead. >>> There is a hidden dependency between: >>> >>> - timers >>> - Block multiqueue >>> - rcutree >>> >>> If timers_dead_cpu() comes later than blk_mq_queue_reinit_notify() >>> that latter function causes a RCU stall. >> >> After this change is applied I am seeing RCU stalls during suspend >> on Tegra. I guess I am hitting the case mentioned above? How should >> this be avoided? > > Contrary to the commit message, this callback ended up in the wrong > place within the sequence. (It was correct in an earlier version, but > the series has been through many changes.) > > Can you try this patch to see if it avoids the stall, please? I have included the patch and I am no longer seeing any RCU stalls and so this does look like it fixed it. Thanks! Jon -- nvpublic