From: John Stultz <john.stultz@linaro.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Gerlando Falauto <gerlando.falauto@keymile.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Richard Cochran <richardcochran@gmail.com>,
Prarit Bhargava <prarit@redhat.com>,
"Brunck, Holger" <Holger.Brunck@keymile.com>,
"Longchamp, Valentin" <Valentin.Longchamp@keymile.com>,
"Bigler, Stefan" <Stefan.Bigler@keymile.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: kernel deadlock
Date: Tue, 10 Sep 2013 09:23:51 -0700 [thread overview]
Message-ID: <522F4797.1050509@linaro.org> (raw)
In-Reply-To: <20130910072908.GA32257@gmail.com>
On 09/10/2013 12:29 AM, Ingo Molnar wrote:
> * John Stultz <john.stultz@linaro.org> wrote:
>
>> Now, I'm still in the dark as to why HRTICK exposes this, but seems like
>> the following patch should resolve the issue (and quiets the lockdep
>> warnings in my testing). Let me know how it works for you!
>>
>> Ingo: This makes me think we really should have some lockdep smarts
>> added to seqlock/seqcount structures. Is there something already
>> discovered thats preventing this, or has this just not yet been tried?
> There's no fundamental reason to not do it, it's a very good idea!
>
>> From 09885df9734aa678ccb61dbef356fea4faeff16c Mon Sep 17 00:00:00 2001
>> From: John Stultz <john.stultz@linaro.org>
>> Date: Mon, 9 Sep 2013 13:07:18 -0700
>> Subject: [PATCH] timekeepeing: Fix HRTICK related deadlock from ntp lock changes
> Cool fix! I think I've seen this deadlock in various incarnations but was
> never able to track it down. Do you have a guesstimate about roughly when
> it was introduced? Is it an ancient bug?
3.10, I believe. So no not ancient, but we've seen and resolved similar
issues in the past (the old printk while holding xtime_lock deadlock).
Hopefully the lockdep enablement helps sort these out for good.
thanks
-john
next prev parent reply other threads:[~2013-09-10 16:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <521F6D06.1040107@keymile.com>
2013-08-29 20:56 ` kernel deadlock Falauto, Gerlando
2013-08-29 23:45 ` John Stultz
2013-08-30 23:04 ` Gerlando Falauto
2013-08-30 23:10 ` John Stultz
2013-08-31 0:48 ` Stephen Boyd
2013-08-31 8:11 ` Gerlando Falauto
2013-09-03 14:57 ` Gerlando Falauto
2013-09-03 17:26 ` John Stultz
2013-09-04 8:11 ` Gerlando Falauto
2013-09-09 20:29 ` John Stultz
2013-09-10 7:29 ` Ingo Molnar
2013-09-10 16:23 ` John Stultz [this message]
2013-09-10 7:56 ` Peter Zijlstra
2013-09-10 8:59 ` Lin Ming
2013-09-10 16:38 ` John Stultz
2013-09-11 0:37 ` Lin Ming
2013-09-09 10:08 ` Peter Zijlstra
2013-09-12 14:42 ` Gerlando Falauto
2003-07-30 20:00 Kernel deadlock Paul Douglas
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