From: Thomas Gleixner <tglx@linutronix.de>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Dave Hansen <dave@sr71.net>, LKML <linux-kernel@vger.kernel.org>,
Dave Jones <davej@redhat.com>,
dhillf@gmail.com, Peter Zijlstra <peterz@infradead.org>
Subject: Re: kernel BUG at kernel/smpboot.c:134!
Date: Sat, 6 Apr 2013 10:31:34 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1304061019000.21884@ionos> (raw)
In-Reply-To: <515FCAC6.8090806@linux.vnet.ibm.com>
On Sat, 6 Apr 2013, Srivatsa S. Bhat wrote:
> Hi Dave,
>
> On 04/06/2013 03:13 AM, Dave Hansen wrote:
> > Hey Thomas,
> >
> > I seem to be running in to smpboot_thread_fn()'s
> >
> > BUG_ON(td->cpu != smp_processor_id());
That should be WARN_ON of course. Stupid me.
> > pretty regularly, both at boot and if I boot with maxcpus=x and then
> > online the CPUs from sysfs after boot. It's a 160-logical-cpu system,
> > so it's quite a beast. I _seem_ to be hitting it more often at higher
> > cpu counts, but it doesn't trigger on bringing up a particular CPU as
> > far as I can tell.
> >
> > This is on a pull of mainline from today, e0a77f263. Any ideas?
> >
>
> Dave Jones had reported a similar problem some time back and Hillf had
> proposed a fix. I guess it slipped through the cracks and never went
> upstream.
>
> Here is the link: https://lkml.org/lkml/2013/1/19/1
This is Hillfs proposed patch:
> --- a/kernel/kthread.c Sat Jan 19 13:03:52 2013
> +++ b/kernel/kthread.c Sat Jan 19 13:17:54 2013
> @@ -306,6 +306,7 @@ struct task_struct *kthread_create_on_cp
> return p;
> set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
> to_kthread(p)->cpu = cpu;
> + __kthread_bind(p, cpu);
> /* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */
> kthread_park(p);
> return p;
That's bogus. Simply because when we create the thread then the thread
status is HP_THREAD_NONE and the path with the BUG_ON is only entered
with status == HP_THREAD_ACTIVE:
if (ht->park && td->status == HP_THREAD_ACTIVE) {
So in Dave's case the thread was already created and has entered
active state.
> >> [ 790.226909] Pid: 3909, comm: migration/135 Tainted: G W 3.9.0-rc5-00184-gb6a9b7f-dirty #118 FUJITSU-SV PRIMEQUEST 1800E2/SB
Hmm, it's the migration thread which trips over this. Oh joy!
Dave, does the issue reproduce with function tracing enabled? For a
first shot it's probably enough to filter on smpboot_* functions plus
sched_switch and sched_wakeup events.
Thanks,
tglx
next prev parent reply other threads:[~2013-04-06 8:31 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-05 21:43 kernel BUG at kernel/smpboot.c:134! Dave Hansen
2013-04-06 7:12 ` Srivatsa S. Bhat
2013-04-06 8:31 ` Thomas Gleixner [this message]
2013-04-07 9:20 ` Thomas Gleixner
2013-04-07 9:50 ` Borislav Petkov
2013-04-08 9:24 ` Thomas Gleixner
2013-04-08 11:55 ` Borislav Petkov
2013-04-08 12:17 ` Thomas Gleixner
2013-04-09 14:38 ` [PATCH] kthread: Prevent unpark race which puts threads on the wrong cpu Thomas Gleixner
2013-04-09 15:55 ` Dave Hansen
2013-04-09 18:43 ` Thomas Gleixner
2013-04-09 19:30 ` Thomas Gleixner
2013-04-09 20:38 ` Dave Hansen
2013-04-09 20:54 ` Dave Hansen
2013-04-10 8:29 ` Thomas Gleixner
2013-04-10 10:51 ` Thomas Gleixner
2013-04-10 19:41 ` Dave Hansen
2013-04-11 10:19 ` Thomas Gleixner
2013-04-11 10:48 ` Srivatsa S. Bhat
2013-04-11 11:43 ` Srivatsa S. Bhat
2013-04-11 11:59 ` Srivatsa S. Bhat
2013-04-11 12:51 ` Thomas Gleixner
2013-04-11 12:54 ` Thomas Gleixner
2013-04-11 13:46 ` Thomas Gleixner
2013-04-11 18:07 ` Dave Hansen
2013-04-11 19:48 ` Thomas Gleixner
2013-04-10 14:03 ` [PATCH] CPU hotplug, smpboot: Fix crash in smpboot_thread_fn() Srivatsa S. Bhat
2013-04-11 8:10 ` Thomas Gleixner
2013-04-11 10:19 ` Srivatsa S. Bhat
2013-04-11 19:16 ` [PATCH] kthread: Prevent unpark race which puts threads on the wrong cpu Srivatsa S. Bhat
2013-04-11 20:47 ` Thomas Gleixner
2013-04-11 21:19 ` Srivatsa S. Bhat
2013-04-12 10:59 ` Thomas Gleixner
2013-04-12 11:26 ` Srivatsa S. Bhat
2013-04-15 19:49 ` Dave Hansen
2013-04-12 10:41 ` Peter Zijlstra
2013-04-12 12:32 ` [tip:core/urgent] " tip-bot for Thomas Gleixner
2014-09-23 0:09 kernel BUG at kernel/smpboot.c:134! Brian Norris
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