From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756714Ab2I1HwT (ORCPT ); Fri, 28 Sep 2012 03:52:19 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:63340 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756004Ab2I1HwR (ORCPT ); Fri, 28 Sep 2012 03:52:17 -0400 X-IronPort-AV: E=Sophos;i="4.80,501,1344182400"; d="scan'208";a="5933266" Message-ID: <506557B6.1050107@cn.fujitsu.com> Date: Fri, 28 Sep 2012 15:54:30 +0800 From: Lai Jiangshan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: Tang Chen 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> In-Reply-To: <1348737586-7018-1-git-send-email-tangchen@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/28 15:52:23, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/28 15:52:24, Serialize complete at 2012/09/28 15:52:24 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); > + } > } > > /*