From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752797AbbHTQqQ (ORCPT ); Thu, 20 Aug 2015 12:46:16 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:42627 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752218AbbHTQqN (ORCPT ); Thu, 20 Aug 2015 12:46:13 -0400 Message-ID: <55D60421.9050904@oracle.com> Date: Thu, 20 Aug 2015 12:45:21 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Peter Zijlstra , mingo@kernel.org, riel@redhat.com CC: dedekind1@gmail.com, linux-kernel@vger.kernel.org, mgorman@suse.de, rostedt@goodmis.org, juri.lelli@arm.com Subject: Re: [RFC][PATCH 2/4] sched: Make sched_class::set_cpus_allowed() unconditional References: <20150515154333.712161952@infradead.org> <20150515154833.614517487@infradead.org> In-Reply-To: <20150515154833.614517487@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/15/2015 11:43 AM, Peter Zijlstra wrote: > Give every class a set_cpus_allowed() method, this enables some small > optimization in the rt,dl implementation by avoiding a double > cpumask_weight() call. > > Signed-off-by: Peter Zijlstra (Intel) Hey Peter, Here's the splat I mentioned earlier. I'm not sure if it's caused by this commit or not, it's just that git blame took me here. [392896.406248] WARNING: CPU: 9 PID: 51 at kernel/sched/core.c:1178 do_set_cpus_allowed+0x1cf/0x480() [392896.407070] Modules linked in: [392896.407408] CPU: 9 PID: 51 Comm: migration/9 Not tainted 4.2.0-rc6-next-20150817-sasha-00041-g9b6b2ab-dirty #2460 [392896.408376] ffffffffab2c2ac0 ffff880477857948 ffffffffaafaf5a9 0000000000000000 [392896.409126] ffff880477857988 ffffffffa1323246 ffffffffa13ab19f ffff880477284000 [392896.409874] ffff8804781e15c0 ffff88006bc03d98 ffffffffae480d20 0000000000000001 [392896.410610] Call Trace: [392896.410947] dump_stack (lib/dump_stack.c:52) [392896.411460] warn_slowpath_common (kernel/panic.c:448) [392896.412037] ? do_set_cpus_allowed (kernel/sched/sched.h:1050 (discriminator 9) kernel/sched/core.c:1180 (discriminator 9)) [392896.412629] warn_slowpath_null (kernel/panic.c:482) [392896.413183] do_set_cpus_allowed (kernel/sched/sched.h:1050 (discriminator 9) kernel/sched/core.c:1180 (discriminator 9)) [392896.413778] cpuset_cpus_allowed_fallback (include/linux/rcupdate.h:911 kernel/cpuset.c:2381) [392896.414415] ? cpuset_cpus_allowed_fallback (kernel/cpuset.c:2378) [392896.415055] select_fallback_rq (kernel/sched/core.c:1589) [392896.415636] ? put_prev_entity (kernel/sched/fair.c:3218) [392896.416234] migration_call (kernel/sched/core.c:5230 kernel/sched/core.c:5492) [392896.416786] notifier_call_chain (kernel/notifier.c:93) [392896.417359] ? cpu_notify (kernel/cpu.c:334) [392896.417863] __raw_notifier_call_chain (kernel/notifier.c:395) [392896.419027] cpu_notify (include/linux/notifier.h:179 kernel/cpu.c:231 kernel/cpu.c:236) [392896.419616] take_cpu_down (kernel/cpu.c:345) [392896.420127] multi_cpu_stop (kernel/stop_machine.c:203) [392896.420671] ? queue_stop_cpus_work (kernel/stop_machine.c:172) [392896.421275] cpu_stopper_thread (kernel/stop_machine.c:440) [392896.421849] ? cpu_stop_create (kernel/stop_machine.c:415) [392896.422404] ? lock_release (kernel/locking/lockdep.c:3643) [392896.422936] ? __raw_callee_save___pv_queued_spin_unlock (??:?) [392896.423710] ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/paravirt.h:802 include/linux/spinlock_api_smp.h:162 kernel/locking/spinlock.c:191) [392896.424354] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2594 kernel/locking/lockdep.c:2636) [392896.424978] ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/preempt.h:77 include/linux/spinlock_api_smp.h:163 kernel/locking/spinlock.c:191) [392896.425610] ? cpu_stop_create (kernel/stop_machine.c:415) [392896.426152] smpboot_thread_fn (kernel/smpboot.c:163 (discriminator 1)) [392896.426707] ? sort_range (kernel/smpboot.c:106) [392896.427252] ? __kthread_parkme (kernel/kthread.c:165) [392896.427817] ? sort_range (kernel/smpboot.c:106) [392896.428332] kthread (kernel/kthread.c:209) [392896.428862] ? kthread_stop (kernel/kthread.c:178) [392896.429399] ? lock_release (kernel/locking/lockdep.c:3643) [392896.429977] ? wait_for_completion (kernel/sched/completion.c:77 kernel/sched/completion.c:93 kernel/sched/completion.c:101 kernel/sched/completion.c:122) Thanks, Sasha