Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758899AbZDAGeU (ORCPT ); Wed, 1 Apr 2009 02:34:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755897AbZDAGeJ (ORCPT ); Wed, 1 Apr 2009 02:34:09 -0400 Received: from ozlabs.org ([203.10.76.45]:43822 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755864AbZDAGeI (ORCPT ); Wed, 1 Apr 2009 02:34:08 -0400 From: Rusty Russell To: Randy Dunlap Subject: Re: 2.6.29 boot hang Date: Wed, 1 Apr 2009 17:03:57 +1030 User-Agent: KMail/1.11.1 (Linux/2.6.27-11-generic; KDE/4.2.1; i686; ; ) Cc: Linux Kernel Mailing List , "Rafael J. Wysocki" , Bjorn Helgaas , andreas.herrmann3@amd.com, Andrew Morton References: <49D280EF.1080507@oracle.com> <200904011012.11527.rusty@rustcorp.com.au> <49D2F2D4.9090008@oracle.com> In-Reply-To: <49D2F2D4.9090008@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200904011703.58179.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3477 Lines: 110 On Wednesday 01 April 2009 15:21:32 Randy Dunlap wrote: > Rusty Russell wrote: > > On Wednesday 01 April 2009 07:15:35 Randy Dunlap wrote: > >> On a 4-proc x86_64 (HP BladeCenter, AMD CPUs) system, booting 2.6.29 > >> (or earlier, back to 2.6.28-6921-g873392c) hangs during boot. > >> > >> git bisect says: > >> 873392ca514f87eae39f53b6944caf85b1a047cb is first bad commit > >> commit 873392ca514f87eae39f53b6944caf85b1a047cb > >> Author: Rusty Russell > >> Date: Wed Dec 31 23:54:56 2008 +1030 > >> > >> PCI: work_on_cpu: use in drivers/pci/pci-driver.c > > > > ... > > > >> If I change CONFIG_MICROCODE_AMD=y to CONFIG_MICROCODE_AMD=n & rebuild, > >> the kernel boots successfully. > > > > How very very odd. My first thought was a deadlock with keventd used > > by work_on_cpu (changed in latest Linus tree), but the microcode code at > > that version doesn't use work_on_cpu. > > Yep, I thought it a bit odd also. > > > So I don't think that's it, but this patch should canonically eliminate it: > > > > Subject: work_on_cpu(): rewrite it to create a kernel thread on demand > > From: Andrew Morton > > This patch doesn't apply to 2.6.29-final, but it does apply to 2.6.29-git8, Err, it has 14 line offset. But here's an adjusted one. diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 1f0c509..08bd795 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -971,20 +971,20 @@ undo: } #ifdef CONFIG_SMP -static struct workqueue_struct *work_on_cpu_wq __read_mostly; struct work_for_cpu { - struct work_struct work; + struct completion completion; long (*fn)(void *); void *arg; long ret; }; -static void do_work_for_cpu(struct work_struct *w) +static int do_work_for_cpu(void *_wfc) { - struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work); - + struct work_for_cpu *wfc = _wfc; wfc->ret = wfc->fn(wfc->arg); + complete(&wfc->completion); + return 0; } /** @@ -995,17 +995,23 @@ static void do_work_for_cpu(struct work_struct *w) * * This will return the value @fn returns. * It is up to the caller to ensure that the cpu doesn't go offline. + * The caller must not hold any locks which would prevent @fn from completing. */ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) { - struct work_for_cpu wfc; - - INIT_WORK(&wfc.work, do_work_for_cpu); - wfc.fn = fn; - wfc.arg = arg; - queue_work_on(cpu, work_on_cpu_wq, &wfc.work); - flush_work(&wfc.work); - + struct task_struct *sub_thread; + struct work_for_cpu wfc = { + .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), + .fn = fn, + .arg = arg, + }; + + sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); + if (IS_ERR(sub_thread)) + return PTR_ERR(sub_thread); + kthread_bind(sub_thread, cpu); + wake_up_process(sub_thread); + wait_for_completion(&wfc.completion); return wfc.ret; } EXPORT_SYMBOL_GPL(work_on_cpu); @@ -1021,8 +1027,4 @@ void __init init_workqueues(void) hotcpu_notifier(workqueue_cpu_callback, 0); keventd_wq = create_workqueue("events"); BUG_ON(!keventd_wq); -#ifdef CONFIG_SMP - work_on_cpu_wq = create_workqueue("work_on_cpu"); - BUG_ON(!work_on_cpu_wq); -#endif } -- 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/