Re: RCU hang on cpu re-hotplug with 2.6.27rc8

From: Andi Kleen
Date: Thu Oct 09 2008 - 04:16:34 EST

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On Thu, Oct 09, 2008 at 09:24:51AM +0200, Thomas Gleixner wrote:
> On Thu, 9 Oct 2008, Andi Kleen wrote:
> > It actually does. The stall detector makes the online echo return after three seconds,
> > although it's not 100% clear to me why.
> >
> > here's the backtrace
> >
> > RCU detected CPU 14 stall (t=4295149800/5928 jiffies)
> > Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #5
> >
> > Call Trace:
> > <IRQ> [<ffffffff8025d188>] __rcu_pending+0x6e/0x1d9
> > [<ffffffff8025d329>] rcu_pending+0x36/0x6e
> > [<ffffffff8023b480>] update_process_times+0x37/0x5b
> > [<ffffffff8024be72>] tick_periodic+0x68/0x74
> > [<ffffffff8024be9f>] tick_handle_periodic+0x21/0x66
> > [<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
> > [<ffffffff8020bfe6>] apic_timer_interrupt+0x66/0x70
> > <EOI> [<ffffffff803adb39>] ? acpi_safe_halt+0x2b/0x3e
> > [<ffffffff803adbfa>] ? acpi_idle_enter_c1+0xae/0x102
> > [<ffffffff804ffdd6>] ? cpuidle_idle_call+0x70/0xa2
> > [<ffffffff8020a097>] ? cpu_idle+0x7e/0x9c
> > [<ffffffff805bef4a>] ? start_secondary+0x157/0x15c
> >
> > Timer issue?
>
> Hmm, this is periodic mode so rather unlikely, but who knows. Does
> this happen with nohz and/or highres as well ?

With nohz/highres enabled it takes much longer to trigger. Normally
it happened near always on the first try, now I had to let a loop
run for several minutes to trigger it.

But the strange thing is that the stall detector doesn't detect
the hotplugged CPUs stalling now, but other unrelated ones.
I only hotplug 14/15, but it reports 3 and 4. In periodic
mode the correct CPUs were reported.

-Andi

Here are the backtraces

Switched to high resolution mode on CPU 14
CPU 15 is now offline
RCU detected CPU 3 stall (t=4294999688/3809 jiffies)
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> [<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff8025f615>] rcu_pending+0x36/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
[<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70
<EOI> [<ffffffff803b0254>] ? acpi_idle_enter_bm+0x2a2/0x312
[<ffffffff803b024a>] ? acpi_idle_enter_bm+0x298/0x312
[<ffffffff805020c2>] ? cpuidle_idle_call+0x70/0xa2
[<ffffffff8020a0a1>] ? cpu_idle+0x88/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c

RCU detected CPU 3 stall (t=4295007688/1250 jiffies)
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> [<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff8025f615>] rcu_pending+0x36/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
[<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70
<EOI> [<ffffffff803b0254>] ? acpi_idle_enter_bm+0x2a2/0x312
[<ffffffff803b024a>] ? acpi_idle_enter_bm+0x298/0x312
[<ffffffff805020c2>] ? cpuidle_idle_call+0x70/0xa2
[<ffffffff8020a0a1>] ? cpu_idle+0x88/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c

RCU detected CPU 3 stall (t=4295012121/2548 jiffies)
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> [<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff8025f640>] rcu_pending+0x61/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
[<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70
<EOI> [<ffffffff803b0254>] ? acpi_idle_enter_bm+0x2a2/0x312
[<ffffffff803b024a>] ? acpi_idle_enter_bm+0x298/0x312
[<ffffffff805020c2>] ? cpuidle_idle_call+0x70/0xa2
[<ffffffff8020a0a1>] ? cpu_idle+0x88/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c

RCU detected CPU 2 stall (t=4295014976/874 jiffies)
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> <3>RCU detected CPU 3 stall (t=4295014976/874 jiffies)
[<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff8025f615>] rcu_pending+0x36/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> [<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70
<EOI> [<ffffffff8024e1b0>] ? tick_nohz_restart_sched_tick+0x15e/0x165
[<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff8025f615>] rcu_pending+0x36/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
[<ffffffff8020a0bd>] ? cpu_idle+0xa4/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c
[<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70

<EOI> [<ffffffff803b0254>] ? acpi_idle_enter_bm+0x2a2/0x312
[<ffffffff803b024a>] ? acpi_idle_enter_bm+0x298/0x312
[<ffffffff805020c2>] ? cpuidle_idle_call+0x70/0xa2
[<ffffffff8020a0a1>] ? cpu_idle+0x88/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c

RCU detected CPU 4 stall (t=4295019871/4894 jiffies)
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> [<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff8025f615>] rcu_pending+0x36/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
RCU detected CPU 6 stall (t=4295019871/4894 jiffies)
Pid: 0, comm: swapper Not tainted 2.6.27-rc9 #6

Call Trace:
<IRQ> [<ffffffff8025f474>] __rcu_pending+0x6e/0x1d9
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
[<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70
<EOI> [<ffffffff803b0254>] ? acpi_idle_enter_bm+0x2a2/0x312
[<ffffffff8025f615>] rcu_pending+0x36/0x6e
[<ffffffff8023bc5d>] update_process_times+0x37/0x5b
[<ffffffff8024de88>] tick_sched_timer+0x81/0xb5
[<ffffffff80247538>] __run_hrtimer+0x56/0x96
[<ffffffff80248002>] hrtimer_interrupt+0xe6/0x14d
[<ffffffff8021bcd2>] smp_apic_timer_interrupt+0x8a/0xa8
[<ffffffff8020bff6>] apic_timer_interrupt+0x66/0x70
<EOI> [<ffffffff8024e1b0>] ? tick_nohz_restart_sched_tick+0x15e/0x165
[<ffffffff803b024a>] ? acpi_idle_enter_bm+0x298/0x312
[<ffffffff805020c2>] ? cpuidle_idle_call+0x70/0xa2
[<ffffffff8020a0a1>] ? cpu_idle+0x88/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c

[<ffffffff8020a0bd>] ? cpu_idle+0xa4/0xae
[<ffffffff805c137a>] ? start_secondary+0x157/0x15c

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Next message: bibo mao: "[patch 0/1] remove existing enclosed mtrr region"
Previous message: John Kacur: "Re: Fwd: [PATCH 7/9] ASoC: Blackfin: I2S CPU DAI driver"
In reply to: Thomas Gleixner: "Re: RCU hang on cpu re-hotplug with 2.6.27rc8"
Next in thread: Paul E. McKenney: "Re: RCU hang on cpu re-hotplug with 2.6.27rc8"
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