Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760118AbXEKJTW (ORCPT ); Fri, 11 May 2007 05:19:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755531AbXEKJTP (ORCPT ); Fri, 11 May 2007 05:19:15 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:37493 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755250AbXEKJTO (ORCPT ); Fri, 11 May 2007 05:19:14 -0400 Date: Fri, 11 May 2007 18:18:13 +0900 Message-ID: <87sla3en1m.wl%takeuchi_satoru@jp.fujitsu.com> From: Satoru Takeuchi To: Rusty Russell Cc: Satoru Takeuchi , Linux Kernel , Srivatsa Vaddagiri , Zwane Mwaikambo , Nathan Lynch , Joel Schopp , Ashok Raj , Heiko Carstens , Gautham R Shenoy Subject: Re: [PATCH 1/2] Fix stop_machine_run problem with naughty real time process In-Reply-To: <87veezeodr.wl%takeuchi_satoru@jp.fujitsu.com> References: <87bqgxrlky.wl%takeuchi_satoru@jp.fujitsu.com> <1178545373.28438.7.camel@localhost.localdomain> <877irkrq8a.wl%takeuchi_satoru@jp.fujitsu.com> <1178593345.28438.29.camel@localhost.localdomain> <87veezeodr.wl%takeuchi_satoru@jp.fujitsu.com> User-Agent: Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (=?ISO-8859-4?Q?Shij=F2?=) APEL/10.6 Emacs/21.4 (i486-pc-linux-gnu) MULE/5.0 (SAKAKI) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2093 Lines: 60 At Fri, 11 May 2007 17:49:20 +0900, Satoru Takeuchi wrote: > > Hi, > > I wrote patches which fixes the problem regarding stop_machine_run() and > cpu hotplug. Sorry, there were extra tabs. Fixed. Thanks, Satoru --- Fix stop_machine_run() problem with naughty real time process stop_machine_run() does its work on "kstopmachine" thread having max priority. However that thread get such priority after woken up. Therefore, in the following case ... - "kstopmachine" try to run on CPU1 - There is a real time process which doesn't relinquish CPU time voluntary on CPU1 ... "kstopmachine" can't start to run and the CPU on which stop_machine_run() is runing hangs up. To fix this problem, call sched_setscheduler() before waking up that thread. Signed-off-by: Satoru Takeuchi Index: linux-2.6.21/kernel/stop_machine.c =================================================================== --- linux-2.6.21.orig/kernel/stop_machine.c 2007-05-11 13:45:34.000000000 +0900 +++ linux-2.6.21/kernel/stop_machine.c 2007-05-11 14:49:17.000000000 +0900 @@ -89,10 +89,6 @@ static void stopmachine_set_state(enum s static int stop_machine(void) { int i, ret = 0; - struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; - - /* One high-prio thread per cpu. We'll do this one. */ - sched_setscheduler(current, SCHED_FIFO, ¶m); atomic_set(&stopmachine_thread_ack, 0); stopmachine_num_threads = 0; @@ -184,6 +180,10 @@ struct task_struct *__stop_machine_run(i p = kthread_create(do_stop, &smdata, "kstopmachine"); if (!IS_ERR(p)) { + struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; + + /* One high-prio thread per cpu. We'll do this one. */ + sched_setscheduler(p, SCHED_FIFO, ¶m); kthread_bind(p, cpu); wake_up_process(p); wait_for_completion(&smdata.done); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/