All of lore.kernel.org
 help / color / mirror / Atom feed
From: Arne Jansen <lists@die-jansens.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
	efault@gmx.de, npiggin@kernel.dk, akpm@linux-foundation.org,
	frank.rowand@am.sony.com, tglx@linutronix.de,
	linux-tip-commits@vger.kernel.org
Subject: Re: [debug patch] printk: Add a printk killswitch to robustify NMI watchdog messages
Date: Sun, 05 Jun 2011 13:57:46 +0200	[thread overview]
Message-ID: <4DEB6F3A.3000109@die-jansens.de> (raw)
In-Reply-To: <20110605113627.GA25724@elte.hu>

On 05.06.2011 13:36, Ingo Molnar wrote:
>
> * Ingo Molnar<mingo@elte.hu>  wrote:
>
>>> If the ticks stop this suggests a lockup within the printk code.
>>> [...]
>>
>> In which case the printk-killswitch patch below (to be applied
>> *instead* of the previous debugging patch i sent) should provide
>> the desired NMI watchdog output on the serial console.
>>
>> Warning: it's entirely untested.

How is the output supposed to come through? shouldn't printk revert
to early_printk instead of just returning?


>
> Note, since this is an SMP box, if the lockup messages show up with
> this patch but are mixed up with each other then adding a spinlock
> around the WARN() would probably help keeping the output serialized.
>
> A simple:
>
>   static DEFINE_SPINLOCK(watchdog_output_lock);
>
>   ...
> 	spin_lock(&watchdog_output_lock);
>   ...
> 	[ the WARN_ON() logic. ]
>   ...
> 	spin_unlock(&watchdog_output_lock);
>   ...
>
> would suffice.
>
> Thanks,
>
> 	Ingo
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/


  reply	other threads:[~2011-06-05 11:58 UTC|newest]

Thread overview: 152+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-05 15:23 [PATCH 00/21] sched: Reduce runqueue lock contention -v6 Peter Zijlstra
2011-04-05 15:23 ` [PATCH 01/21] sched: Provide scheduler_ipi() callback in response to smp_send_reschedule() Peter Zijlstra
2011-04-13 21:15   ` Tony Luck
2011-04-13 21:38     ` Peter Zijlstra
2011-04-14  8:31   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 02/21] sched: Always provide p->on_cpu Peter Zijlstra
2011-04-14  8:31   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 03/21] mutex: Use p->on_cpu for the adaptive spin Peter Zijlstra
2011-04-14  8:32   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 04/21] sched: Change the ttwu success details Peter Zijlstra
2011-04-13  9:23   ` Peter Zijlstra
2011-04-13 10:48     ` Peter Zijlstra
2011-04-13 11:06       ` Peter Zijlstra
2011-04-13 18:39         ` Tejun Heo
2011-04-13 19:11           ` Peter Zijlstra
2011-04-14  8:32   ` [tip:sched/locking] sched: Change the ttwu() " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 05/21] sched: Clean up ttwu stats Peter Zijlstra
2011-04-14  8:33   ` [tip:sched/locking] sched: Clean up ttwu() stats tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 06/21] sched: Provide p->on_rq Peter Zijlstra
2011-04-14  8:33   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 07/21] sched: Serialize p->cpus_allowed and ttwu() using p->pi_lock Peter Zijlstra
2011-04-14  8:34   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 08/21] sched: Drop the rq argument to sched_class::select_task_rq() Peter Zijlstra
2011-04-14  8:34   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 09/21] sched: Remove rq argument to sched_class::task_waking() Peter Zijlstra
2011-04-14  8:35   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 10/21] sched: Deal with non-atomic min_vruntime reads on 32bits Peter Zijlstra
2011-04-14  8:35   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 11/21] sched: Delay task_contributes_to_load() Peter Zijlstra
2011-04-14  8:35   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 12/21] sched: Also serialize ttwu_local() with p->pi_lock Peter Zijlstra
2011-04-14  8:36   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 13/21] sched: Add p->pi_lock to task_rq_lock() Peter Zijlstra
2011-04-14  8:36   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-06-01 13:58     ` Arne Jansen
2011-06-01 16:35       ` Peter Zijlstra
2011-06-01 17:20         ` Arne Jansen
2011-06-01 18:09           ` Peter Zijlstra
2011-06-01 18:44             ` Peter Zijlstra
2011-06-01 19:30               ` Arne Jansen
2011-06-01 21:09                 ` Linus Torvalds
2011-06-03  9:15                   ` Peter Zijlstra
2011-06-03 10:02                     ` Arne Jansen
2011-06-03 10:30                       ` Peter Zijlstra
2011-06-03 11:52                         ` Arne Jansen
2011-06-05  8:17                         ` Ingo Molnar
2011-06-05  8:53                           ` Arne Jansen
2011-06-05  9:41                             ` Ingo Molnar
2011-06-05  9:45                               ` Ingo Molnar
2011-06-05  9:43                           ` Arne Jansen
2011-06-05  9:55                             ` Ingo Molnar
2011-06-05 10:22                               ` Arne Jansen
2011-06-05 11:01                                 ` Ingo Molnar
2011-06-05 11:19                                   ` [debug patch] printk: Add a printk killswitch to robustify NMI watchdog messages Ingo Molnar
2011-06-05 11:36                                     ` Ingo Molnar
2011-06-05 11:57                                       ` Arne Jansen [this message]
2011-06-05 13:39                                         ` Ingo Molnar
2011-06-05 13:54                                           ` Arne Jansen
2011-06-05 14:06                                             ` Ingo Molnar
2011-06-05 14:45                                               ` Arne Jansen
2011-06-05 14:10                                             ` Ingo Molnar
2011-06-05 14:31                                               ` Arne Jansen
2011-06-05 15:13                                                 ` Ingo Molnar
2011-06-05 15:26                                                   ` Ingo Molnar
2011-06-05 15:32                                                     ` Ingo Molnar
2011-06-05 16:07                                                       ` Arne Jansen
2011-06-05 16:35                                                         ` Arne Jansen
2011-06-05 16:50                                                           ` Arne Jansen
2011-06-05 17:20                                                             ` Ingo Molnar
2011-06-05 17:42                                                               ` Arne Jansen
2011-06-05 18:59                                                                 ` Ingo Molnar
2011-06-05 19:30                                                                   ` Arne Jansen
2011-06-05 19:44                                                                     ` Ingo Molnar
2011-06-05 20:15                                                                       ` Arne Jansen
2011-06-06  6:56                                                                         ` Arne Jansen
2011-06-06  9:01                                                                         ` Peter Zijlstra
2011-06-06  9:18                                                                           ` Arne Jansen
2011-06-06  9:24                                                                             ` Peter Zijlstra
2011-06-06  9:52                                                                               ` Peter Zijlstra
2011-06-06 10:00                                                                           ` Arne Jansen
2011-06-06 10:26                                                                             ` Peter Zijlstra
2011-06-06 13:25                                                                               ` Peter Zijlstra
2011-06-06 15:04                                                                           ` Ingo Molnar
2011-06-06 15:08                                                                             ` Ingo Molnar
2011-06-06 17:44                                                                               ` Mike Galbraith
2011-06-07  5:20                                                                           ` Mike Galbraith
2011-06-06 13:10                                                                   ` Ingo Molnar
2011-06-06 13:12                                                                     ` Peter Zijlstra
2011-06-06 13:21                                                                       ` Ingo Molnar
2011-06-06 13:31                                                                         ` Peter Zijlstra
2011-06-06  7:34                                                     ` Arne Jansen
2011-06-05 15:34                                                   ` Arne Jansen
2011-06-06  8:38                                                   ` Peter Zijlstra
2011-06-06 14:58                                                     ` Ingo Molnar
2011-06-06 15:09                                                       ` Peter Zijlstra
2011-06-06 15:47                                                         ` Peter Zijlstra
2011-06-06 15:52                                                           ` Ingo Molnar
2011-06-06 16:00                                                             ` Peter Zijlstra
2011-06-06 16:08                                                               ` Ingo Molnar
2011-06-06 16:12                                                                 ` Peter Zijlstra
2011-06-06 16:17                                                                   ` Ingo Molnar
2011-06-06 16:38                                                                     ` Arne Jansen
2011-06-06 16:45                                                                       ` Arne Jansen
2011-06-06 16:53                                                                         ` Peter Zijlstra
2011-06-06 17:07                                                                         ` Ingo Molnar
2011-06-06 17:11                                                                           ` Peter Zijlstra
2011-06-08 15:50                                                                             ` Peter Zijlstra
2011-06-08 19:17                                                                               ` Ingo Molnar
2011-06-08 19:27                                                                                 ` Linus Torvalds
2011-06-08 20:32                                                                                   ` Peter Zijlstra
2011-06-08 20:53                                                                                     ` Linus Torvalds
2011-06-08 20:54                                                                                     ` Thomas Gleixner
2011-06-08 19:45                                                                                 ` Peter Zijlstra
2011-06-08 20:52                                                                                   ` Ingo Molnar
2011-06-08 21:49                                                                                     ` Peter Zijlstra
2011-06-08 21:57                                                                                       ` Thomas Gleixner
2011-06-06 16:44                                                                     ` Peter Zijlstra
2011-06-06 16:50                                                                       ` Peter Zijlstra
2011-06-06 17:13                                                                         ` Ingo Molnar
2011-06-06 17:04                                                                       ` Peter Zijlstra
2011-06-06 17:11                                                                       ` Ingo Molnar
2011-06-06 17:57                                                                         ` Arne Jansen
2011-06-06 18:07                                                                           ` Ingo Molnar
2011-06-06 18:14                                                                             ` Arne Jansen
2011-06-06 18:19                                                                             ` Peter Zijlstra
2011-06-06 22:08                                                                               ` Ingo Molnar
2011-06-03 12:44                       ` [tip:sched/locking] sched: Add p->pi_lock to task_rq_lock() Linus Torvalds
2011-06-03 13:05                         ` Arne Jansen
2011-06-04 21:29                           ` Linus Torvalds
2011-06-04 22:08                             ` Peter Zijlstra
2011-06-04 22:50                               ` Linus Torvalds
2011-06-05  6:01                               ` Arne Jansen
2011-06-05  7:57                                 ` Mike Galbraith
2011-04-05 15:23 ` [PATCH 14/21] sched: Drop rq->lock from first part of wake_up_new_task() Peter Zijlstra
2011-04-14  8:37   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 15/21] sched: Drop rq->lock from sched_exec() Peter Zijlstra
2011-04-14  8:37   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 16/21] sched: Remove rq->lock from the first half of ttwu() Peter Zijlstra
2011-04-14  8:38   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 17/21] sched: Remove rq argument from ttwu_stat() Peter Zijlstra
2011-04-14  8:38   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 18/21] sched: Rename ttwu_post_activation Peter Zijlstra
2011-04-14  8:39   ` [tip:sched/locking] sched: Rename ttwu_post_activation() to ttwu_do_wakeup() tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 19/21] sched: Restructure ttwu some more Peter Zijlstra
2011-04-14  8:39   ` [tip:sched/locking] sched: Restructure ttwu() " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 20/21] sched: Move the second half of ttwu() to the remote cpu Peter Zijlstra
2011-04-14  8:39   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 21/21] sched: Remove need_migrate_task() Peter Zijlstra
2011-04-14  8:40   ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:59 ` [PATCH 00/21] sched: Reduce runqueue lock contention -v6 Peter Zijlstra
2011-04-06 11:00 ` Peter Zijlstra
2011-04-27 16:54 ` Dave Kleikamp

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4DEB6F3A.3000109@die-jansens.de \
    --to=lists@die-jansens.de \
    --cc=akpm@linux-foundation.org \
    --cc=efault@gmx.de \
    --cc=frank.rowand@am.sony.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tip-commits@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=mingo@redhat.com \
    --cc=npiggin@kernel.dk \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.