From: Fengguang Wu <fengguang.wu@intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Michael Wang <wangyun@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Suresh Siddha <suresh.b.siddha@intel.com>,
Venkatesh Pallipadi <venki@google.com>
Subject: Re: WARNING: cpu_is_offline() at native_smp_send_reschedule()
Date: Fri, 7 Sep 2012 16:17:29 +0800 [thread overview]
Message-ID: <20120907081729.GA19473@localhost> (raw)
In-Reply-To: <1347002596.18408.84.camel@twins>
On Fri, Sep 07, 2012 at 09:23:16AM +0200, Peter Zijlstra wrote:
> On Fri, 2012-09-07 at 09:20 +0800, Fengguang Wu wrote:
>
> > FYI, the bisect result is
> >
> > commit 554cecaf733623b327eef9652b65965eb1081b81
> > Author: Diwakar Tundlam <dtundlam@nvidia.com>
> > Date: Wed Mar 7 14:44:26 2012 -0800
> >
> > sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer
> >
> > The 'next_balance' field of 'nohz' idle balancer must be initialized
> > to jiffies. Since jiffies is initialized to negative 300 seconds the
> > 'nohz' idle balancer does not run for the first 300s (5mins) after
> > bootup. If no new processes are spawed or no idle cycles happen, the
> > load on the cpus will remain unbalanced for that duration.
> >
> > Signed-off-by: Diwakar Tundlam <dtundlam@nvidia.com>
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > Link: http://lkml.kernel.org/r/1DD7BFEDD3147247B1355BEFEFE4665237994F30EF@HQMAIL04.nvidia.com
> > Signed-off-by: Ingo Molnar <mingo@elte.hu>
>
> Oh fun.. does the below 'fix' it?
>
> The thing I'm thinking of a tick happening right after we set jiffies
> but before the zalloc (specifically the memset(0)) is complete. Since
> we've already registered the softirq we can end up in the load-balancer
> and see a completely weird idle mask.
>
> Hmm?
The may be more causes, since I still get the warning:
[ 9.816279] reboot: machine restart
[ 9.835796] ------------[ cut here ]------------
[ 9.836558] WARNING: at /c/wfg/linux/arch/x86/kernel/smp.c:123 native_smp_send_reschedule+0x46/0x50()
[ 9.839792] Pid: 18, comm: kworker/0:1 Not tainted 3.6.0-rc3-bisect-00005-gb374aa1-dirty #49
[ 9.839792] Call Trace:
[ 9.839792] [<7902f42a>] warn_slowpath_common+0x5a/0x80
[ 9.839792] [<7901ee16>] ? native_smp_send_reschedule+0x46/0x50
[ 9.839792] [<7901ee16>] ? native_smp_send_reschedule+0x46/0x50
[ 9.839792] [<7902f4fd>] warn_slowpath_null+0x1d/0x20
[ 9.839792] [<7901ee16>] native_smp_send_reschedule+0x46/0x50
[ 9.839792] [<7905fdad>] trigger_load_balance+0x1bd/0x250
[ 9.839792] [<79056d14>] scheduler_tick+0xd4/0x100
[ 9.839792] [<7903bde5>] update_process_times+0x55/0x70
[ 9.839792] [<79071187>] tick_sched_timer+0x57/0xb0
[ 9.839792] [<793accee>] ? do_raw_spin_unlock+0x4e/0x90
[ 9.839792] [<7904e0b7>] __run_hrtimer.isra.29+0x57/0x100
[ 9.839792] [<79071130>] ? tick_nohz_handler+0xe0/0xe0
[ 9.839792] [<7904ed45>] hrtimer_interrupt+0xe5/0x280
[ 9.839792] [<7905a5a7>] ? sched_clock_cpu+0xc7/0x150
[ 9.839792] [<7901f9a4>] smp_apic_timer_interrupt+0x54/0x90
[ 9.839792] [<79882631>] apic_timer_interrupt+0x31/0x40
[ 9.839792] [<7905007b>] ? call_srcu+0x2b/0x70
[ 9.839792] [<793a00e0>] ? __bitmap_intersects+0x10/0x80
[ 9.839792] [<7988194f>] ? _raw_spin_unlock_irq+0x1f/0x40
[ 9.839792] [<7905307f>] finish_task_switch+0x7f/0xd0
[ 9.839792] [<79053038>] ? finish_task_switch+0x38/0xd0
[ 9.839792] [<7988044a>] __schedule+0x38a/0x770
[ 9.839792] [<79045529>] ? worker_thread+0x1a9/0x380
[ 9.839792] [<793accee>] ? do_raw_spin_unlock+0x4e/0x90
[ 9.839792] [<7988084e>] schedule+0x1e/0x50
[ 9.839792] [<7904552e>] worker_thread+0x1ae/0x380
[ 9.839792] [<79056ed9>] ? complete+0x49/0x60
[ 9.839792] [<79045380>] ? manage_workers.isra.23+0x250/0x250
[ 9.839792] [<79049ff8>] kthread+0x78/0x80
[ 9.839792] [<79880000>] ? __up.isra.0+0xd/0x2d
[ 9.839792] [<79049f80>] ? insert_kthread_work+0x70/0x70
[ 9.839792] [<798830c6>] kernel_thread_helper+0x6/0xd
Thanks,
Fengguang
prev parent reply other threads:[~2012-09-07 8:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 1:11 WARNING: cpu_is_offline() at native_smp_send_reschedule() Fengguang Wu
2012-09-05 4:35 ` Michael Wang
2012-09-05 10:54 ` Peter Zijlstra
2012-09-05 12:57 ` Fengguang Wu
2012-09-07 1:20 ` Fengguang Wu
2012-09-07 3:08 ` Michael Wang
2012-09-07 7:23 ` Peter Zijlstra
2012-09-07 8:17 ` Fengguang Wu [this message]
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