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From: Peter Zijlstra <peterz@infradead.org>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	alexander.levin@verizon.com
Subject: Re: [PATCH 3/4] sched: WARN when migrating to an offline CPU
Date: Thu, 28 Sep 2017 12:35:41 +0200
Message-ID: <20170928103541.2adtamm7koi4k5zh@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+1xoqe0AW9acyvdtE+=CN8FisQrXH2wnwvakSXapg3sKE4khw@mail.gmail.com>

On Thu, Sep 28, 2017 at 02:14:15AM -0700, Sasha Levin wrote:
> On Thu, Sep 7, 2017 at 8:03 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > Migrating tasks to offline CPUs is a pretty big fail, warn about it.
> 
> Hey Peter,
> 
> This seems to get hit on the latest -next:
> 
> [2035565360.446794] Unregister pv shared memory for cpu 2
> [2035565360.467930] numa_remove_cpu cpu 2 node 2: mask now 6
> [2035565360.471431] ------------[ cut here ]------------
> [2035565360.472548] WARNING: CPU: 2 PID: 24 at > kernel/sched/core.c:1178 set_task_cpu (kernel/sched/core.c:1157)
> [2035565360.473840] Modules linked in:
> [2035565360.474632] CPU: 2 PID: 24 Comm: migration/2 Not tainted > 4.14.0-rc2-next-20170927+ #252

Urgh, weird. That really shouldn't happen. Can you easily reproduce?

> [2035565360.491836] Call Trace:
> [2035565360.492301]  <IRQ>
> [2035565360.492710] detach_task.isra.80 (kernel/sched/fair.c:6816)
> [2035565360.493430] load_balance (./include/linux/list.h:78 > kernel/sched/fair.c:6902 kernel/sched/fair.c:8201)
> [2035565360.494094] ? find_busiest_group (kernel/sched/fair.c:8133)
> [2035565360.494861] ? rebalance_domains (kernel/sched/fair.c:8785)
> [2035565360.495571] rebalance_domains (kernel/sched/fair.c:8829)
> [2035565360.496292] ? find_next_bit (lib/find_bit.c:65)
> [2035565360.496961] ? pick_next_task_fair (kernel/sched/fair.c:8779)
> [2035565360.497753] ? check_preemption_disabled (lib/smp_processor_id.c:52)
> [2035565360.498574] run_rebalance_domains (kernel/sched/fair.c:9052)
> [2035565360.499318] ? check_preemption_disabled (lib/smp_processor_id.c:52)
> [2035565360.500388] __do_softirq (kernel/softirq.c:284 > ./include/linux/jump_label.h:141 ./include/trace/events/irq.h:141 > kernel/softirq.c:285)
> [2035565360.501039] ? hrtimer_interrupt (kernel/time/hrtimer.c:1370)
> [2035565360.502014] irq_exit (kernel/softirq.c:364 kernel/softirq.c:405)
> [2035565360.502598] smp_apic_timer_interrupt > (./arch/x86/include/asm/irq_regs.h:26 > arch/x86/kernel/apic/apic.c:1043)
> [2035565360.503605] apic_timer_interrupt (arch/x86/entry/entry_64.S:770)
> [2035565360.504313]  </IRQ>

  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-07 15:03 [PATCH 0/4] sched: Fix some load-balancer vs hotplug holes Peter Zijlstra
2017-09-07 15:03 ` [PATCH 1/4] sched/fair: Avoid newidle balance for !active CPUs Peter Zijlstra
2017-09-12 18:04   ` [tip:sched/urgent] " tip-bot for Peter Zijlstra
2017-09-07 15:03 ` [PATCH 2/4] sched/fair: Plug hole between hotplug and active load_balance Peter Zijlstra
2017-09-12 18:05   ` [tip:sched/urgent] sched/fair: Plug hole between hotplug and active_load_balance() tip-bot for Peter Zijlstra
2017-09-07 15:03 ` [PATCH 3/4] sched: WARN when migrating to an offline CPU Peter Zijlstra
2017-09-12 18:05   ` [tip:sched/urgent] sched/core: WARN() " tip-bot for Peter Zijlstra
2017-09-28  9:14   ` [PATCH 3/4] sched: WARN " Sasha Levin
2017-09-28 10:35     ` Peter Zijlstra [this message]
2017-09-28 11:03       ` Levin, Alexander (Sasha Levin)
2017-09-28 11:42         ` Peter Zijlstra
2017-09-29 11:11           ` Peter Zijlstra
2017-10-07  2:07             ` Levin, Alexander (Sasha Levin)
2017-10-07  9:15               ` Peter Zijlstra
     [not found]                 ` <20171007174327.ky6g5viokxg5ysdm@sasha-lappy>
2017-10-09  8:04                   ` Peter Zijlstra
2017-10-10  1:18                     ` Levin, Alexander (Sasha Levin)
2017-09-07 15:03 ` [PATCH 4/4] sched/debug: Add debugfs knob for "sched_debug" Peter Zijlstra
2017-09-12 18:05   ` [tip:sched/urgent] " tip-bot for Peter Zijlstra

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