From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764397AbdAIXkq (ORCPT ); Mon, 9 Jan 2017 18:40:46 -0500 Received: from mail.skyhub.de ([78.46.96.112]:42517 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756210AbdAIXko (ORCPT ); Mon, 9 Jan 2017 18:40:44 -0500 Date: Tue, 10 Jan 2017 00:40:39 +0100 From: Borislav Petkov To: "Paul E. McKenney" Cc: "Zheng, Lv" , "Rafael J. Wysocki" , "Wysocki, Rafael J" , "Moore, Robert" , J?rg R?del , lkml , Linux ACPI Subject: Re: 174cc7187e6f ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux kernel Message-ID: <20170109234039.mfefmv5dv4shxnfn@pd.tnic> References: <20170108010158.b62eovaxsbmhfnkb@pd.tnic> <20170108130355.vxhjmj6dlkqw6hyq@pd.tnic> <1AE640813FDE7649BE1B193DEA596E886CE27B7E@SHSMSX101.ccr.corp.intel.com> <1AE640813FDE7649BE1B193DEA596E886CE27BEE@SHSMSX101.ccr.corp.intel.com> <20170109093329.jd7uwlcpci4icpd3@pd.tnic> <20170109221831.GC3800@linux.vnet.ibm.com> <20170109231501.xrhwsv46mznw3kqt@pd.tnic> <20170109233204.GG3800@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170109233204.GG3800@linux.vnet.ibm.com> User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 09, 2017 at 03:32:04PM -0800, Paul E. McKenney wrote: > We could move rcu_scheduler_starting() later, as long as there > is no chance of preemption or context switch before it is invoked. > Would that help in this case, or are we already context switching before > acpi_os_map_cleanup() is invoked? (If we are already context switching, > short-circuiting synchronize_rcu_expedited() would be a bug.) Hmm, how about the below? It would still happen before /* * The boot idle thread must execute schedule() * at least once to get things moving: */ init_idle_bootup_task(current); schedule_preempt_disabled(); in rest_init() and right after native_smp_prepare_cpus() which is where we're splatting. Lemme run it. Even if it works, we would have to stress-test this seriously... --- diff --git a/init/main.c b/init/main.c index b0c9d6facef9..9be221cc87c3 100644 --- a/init/main.c +++ b/init/main.c @@ -385,7 +385,6 @@ static noinline void __ref rest_init(void) { int pid; - rcu_scheduler_starting(); /* * We need to spawn init first so that it obtains pid 1, however * the init task will end up wanting to create kthreads, which, if @@ -1019,6 +1018,8 @@ static noinline void __init kernel_init_freeable(void) smp_prepare_cpus(setup_max_cpus); + rcu_scheduler_starting(); + workqueue_init(); do_pre_smp_initcalls(); -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.