From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271Ab2JHFqf (ORCPT ); Mon, 8 Oct 2012 01:46:35 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:44802 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751311Ab2JHFqd (ORCPT ); Mon, 8 Oct 2012 01:46:33 -0400 X-IronPort-AV: E=Sophos;i="4.80,551,1344182400"; d="scan'208";a="5958068" Message-ID: <50726871.1060301@cn.fujitsu.com> Date: Mon, 08 Oct 2012 13:45:21 +0800 From: Tang Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Lai Jiangshan CC: tony.luck@intel.com, bp@amd64.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, Miao Xie , Tejun Heo , Peter Zijlstra Subject: Re: [PATCH] Do not change worker's running cpu in cmci_rediscover(). References: <1348737586-7018-1-git-send-email-tangchen@cn.fujitsu.com> <506557B6.1050107@cn.fujitsu.com> In-Reply-To: <506557B6.1050107@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/10/08 13:46:25, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/10/08 13:46:26, Serialize complete at 2012/10/08 13:46:26 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, Would you please help to review this patch ? Thanks. :) On 09/28/2012 03:54 PM, Lai Jiangshan wrote: > Add CC: Tejun Heo, Peter Zijlstra. > > Hi, Tejun > > This is a bug whose root cause is the same as > https://bugzilla.kernel.org/show_bug.cgi?id=47301. > > Acked-by: Lai Jiangshan > > thanks, > Lai > > > On 09/27/2012 05:19 PM, Tang Chen wrote: >> 1. cmci_rediscover() is only called by the CPU_POST_DEAD event handler, which >> means the corresponding cpu has already dead. As a result, it won't be accessed >> in the for_each_online_cpu loop. >> So, we could change the if(cpu == dying) statement into a BUG_ON(). >> >> 2. cmci_rediscover() used set_cpus_allowed_ptr() to change the current process's >> running cpu, and migrate itself to the dest cpu. But worker processes are not >> allowed to be migrated. If current is a worker, the worker will be migrated to >> another cpu, but the corresponding worker_pool is still on the original cpu. >> >> In this case, the following BUG_ON in try_to_wake_up_local() will be triggered: >> BUG_ON(rq != this_rq()); >> >> This will cause the kernel panic. >> >> This patch removes the set_cpus_allowed_ptr() call, and put the cmci rediscover >> jobs onto all the other cpus using system_wq. This could bring some delay for >> the jobs. >> >> The following is call trace. >> >> [ 6155.451107] ------------[ cut here ]------------ >> [ 6155.452019] kernel BUG at kernel/sched/core.c:1654! >> ...... >> [ 6155.452019] RIP: 0010:[] [] try_to_wake_up_local+0x115/0x130 >> ...... >> [ 6155.452019] Call Trace: >> [ 6155.452019] [] __schedule+0x764/0x880 >> [ 6155.452019] [] schedule+0x29/0x70 >> [ 6155.452019] [] schedule_timeout+0x235/0x2d0 >> [ 6155.452019] [] ? mark_held_locks+0x8d/0x140 >> [ 6155.452019] [] ? __lock_release+0x133/0x1a0 >> [ 6155.452019] [] ? _raw_spin_unlock_irq+0x30/0x50 >> [ 6155.452019] [] ? trace_hardirqs_on_caller+0x105/0x190 >> [ 6155.452019] [] wait_for_common+0x12b/0x180 >> [ 6155.452019] [] ? try_to_wake_up+0x2f0/0x2f0 >> [ 6155.452019] [] wait_for_completion+0x1d/0x20 >> [ 6155.452019] [] stop_one_cpu+0x8a/0xc0 >> [ 6155.452019] [] ? __migrate_task+0x1a0/0x1a0 >> [ 6155.452019] [] ? complete+0x28/0x60 >> [ 6155.452019] [] set_cpus_allowed_ptr+0x128/0x130 >> [ 6155.452019] [] cmci_rediscover+0xf5/0x140 >> [ 6155.452019] [] mce_cpu_callback+0x18d/0x19d >> [ 6155.452019] [] notifier_call_chain+0x67/0x150 >> [ 6155.452019] [] __raw_notifier_call_chain+0xe/0x10 >> [ 6155.452019] [] __cpu_notify+0x20/0x40 >> [ 6155.452019] [] cpu_notify_nofail+0x15/0x30 >> [ 6155.452019] [] _cpu_down+0x262/0x2e0 >> [ 6155.452019] [] cpu_down+0x36/0x50 >> [ 6155.452019] [] acpi_processor_remove+0x50/0x11e >> [ 6155.452019] [] acpi_device_remove+0x90/0xb2 >> [ 6155.452019] [] __device_release_driver+0x7c/0xf0 >> [ 6155.452019] [] device_release_driver+0x2f/0x50 >> [ 6155.452019] [] acpi_bus_remove+0x32/0x6d >> [ 6155.452019] [] acpi_bus_trim+0x87/0xee >> [ 6155.452019] [] acpi_bus_hot_remove_device+0x88/0x16b >> [ 6155.452019] [] acpi_os_execute_deferred+0x27/0x34 >> [ 6155.452019] [] process_one_work+0x219/0x680 >> [ 6155.452019] [] ? process_one_work+0x1b8/0x680 >> [ 6155.452019] [] ? acpi_os_wait_events_complete+0x23/0x23 >> [ 6155.452019] [] worker_thread+0x12e/0x320 >> [ 6155.452019] [] ? manage_workers+0x110/0x110 >> [ 6155.452019] [] kthread+0xc6/0xd0 >> [ 6155.452019] [] kernel_thread_helper+0x4/0x10 >> [ 6155.452019] [] ? retint_restore_args+0x13/0x13 >> [ 6155.452019] [] ? __init_kthread_worker+0x70/0x70 >> [ 6155.452019] [] ? gs_change+0x13/0x13 >> >> Signed-off-by: Tang Chen >> Signed-off-by: Miao Xie >> --- >> arch/x86/kernel/cpu/mcheck/mce_intel.c | 34 +++++++++++++++++-------------- >> 1 files changed, 19 insertions(+), 15 deletions(-) >> >> diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c >> index 38e49bc..f7d9795 100644 >> --- a/arch/x86/kernel/cpu/mcheck/mce_intel.c >> +++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c >> @@ -163,34 +163,38 @@ void cmci_clear(void) >> raw_spin_unlock_irqrestore(&cmci_discover_lock, flags); >> } >> >> +static long cmci_rediscover_work_func(void *arg) >> +{ >> + int banks; >> + >> + /* Recheck banks in case CPUs don't all have the same */ >> + if (cmci_supported(&banks)) >> + cmci_discover(banks, 0); >> + >> + return 0; >> +} >> + >> /* >> * After a CPU went down cycle through all the others and rediscover >> * Must run in process context. >> */ >> void cmci_rediscover(int dying) >> { >> - int banks; >> - int cpu; >> - cpumask_var_t old; >> + int cpu, banks; >> >> if (!cmci_supported(&banks)) >> return; >> - if (!alloc_cpumask_var(&old, GFP_KERNEL)) >> - return; >> - cpumask_copy(old,¤t->cpus_allowed); >> >> for_each_online_cpu(cpu) { >> - if (cpu == dying) >> - continue; >> - if (set_cpus_allowed_ptr(current, cpumask_of(cpu))) >> + BUG_ON(cpu == dying); >> + >> + if (cpu == smp_processor_id()) { >> + cmci_rediscover_work_func(NULL); >> continue; >> - /* Recheck banks in case CPUs don't all have the same */ >> - if (cmci_supported(&banks)) >> - cmci_discover(banks, 0); >> - } >> + } >> >> - set_cpus_allowed_ptr(current, old); >> - free_cpumask_var(old); >> + work_on_cpu(cpu, cmci_rediscover_work_func, NULL); >> + } >> } >> >> /* > >