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From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>,
	Intel graphics driver community testing & development
	<intel-gfx@lists.freedesktop.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Linux kernel development <linux-kernel@vger.kernel.org>,
	David Hildenbrand <dahi@linux.vnet.ibm.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] [RFC] kernel/cpu: Use lockref for online CPU reference counting
Date: Thu, 18 Feb 2016 12:39:06 +0200	[thread overview]
Message-ID: <1455791946.9851.24.camel@linux.intel.com> (raw)
In-Reply-To: <20160217163747.GJ6357@twins.programming.kicks-ass.net>

On ke, 2016-02-17 at 17:37 +0100, Peter Zijlstra wrote:
> On Wed, Feb 17, 2016 at 05:33:51PM +0100, Daniel Vetter wrote:
> > On Wed, Feb 17, 2016 at 05:14:57PM +0100, Peter Zijlstra wrote:
> > > On Wed, Feb 17, 2016 at 05:13:21PM +0100, Daniel Vetter wrote:
> > > > And for context we're hitting this on CI in a bunch of our machines, which
> > > 
> > > What's CI ?
> > 
> > Continuous integration, aka our own farm of machines dedicated to running
> > i915.ko testcases. Kinda like 0day (it does pre-merge testing on the m-l
> > and also post-merge on our own little integration tree), but for just the
> > graphics team and our needs.
> 
> So what patch triggered this new issue? Did cpufreq change or what?

It appeared right after enabling lockdep debugging on the continuous
integration system. So we do not have a history of it not being there.

Taking an another look at my code, it could indeed end up in double-
wait-looping scenario if suspend and initialization was performed
simultaneously (it had a couple of other bugs too, fixed in v2).
Strange thing is, I think that should have been caught by cpuhp_lock_*
lockdep tracking.

So I'll move the discussion to linux-pm list to change the CPUfreq code. Thanks for the comments.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

WARNING: multiple messages have this Message-ID (diff)
From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
	Intel graphics driver community testing & development 
	<intel-gfx@lists.freedesktop.org>,
	Linux kernel development <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	David Hildenbrand <dahi@linux.vnet.ibm.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	"Gautham R. Shenoy" <ego@linux.vnet.ibm.com>,
	Chris Wilson <chris@chris-wilson.co.uk>
Subject: Re: [Intel-gfx] [PATCH] [RFC] kernel/cpu: Use lockref for online CPU reference counting
Date: Thu, 18 Feb 2016 12:39:06 +0200	[thread overview]
Message-ID: <1455791946.9851.24.camel@linux.intel.com> (raw)
In-Reply-To: <20160217163747.GJ6357@twins.programming.kicks-ass.net>

On ke, 2016-02-17 at 17:37 +0100, Peter Zijlstra wrote:
> On Wed, Feb 17, 2016 at 05:33:51PM +0100, Daniel Vetter wrote:
> > On Wed, Feb 17, 2016 at 05:14:57PM +0100, Peter Zijlstra wrote:
> > > On Wed, Feb 17, 2016 at 05:13:21PM +0100, Daniel Vetter wrote:
> > > > And for context we're hitting this on CI in a bunch of our machines, which
> > > 
> > > What's CI ?
> > 
> > Continuous integration, aka our own farm of machines dedicated to running
> > i915.ko testcases. Kinda like 0day (it does pre-merge testing on the m-l
> > and also post-merge on our own little integration tree), but for just the
> > graphics team and our needs.
> 
> So what patch triggered this new issue? Did cpufreq change or what?

It appeared right after enabling lockdep debugging on the continuous
integration system. So we do not have a history of it not being there.

Taking an another look at my code, it could indeed end up in double-
wait-looping scenario if suspend and initialization was performed
simultaneously (it had a couple of other bugs too, fixed in v2).
Strange thing is, I think that should have been caught by cpuhp_lock_*
lockdep tracking.

So I'll move the discussion to linux-pm list to change the CPUfreq code. Thanks for the comments.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation

  reply	other threads:[~2016-02-18 10:39 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-15 12:36 [PATCH] [RFC] kernel/cpu: Use lockref for online CPU reference counting Joonas Lahtinen
2016-02-15 12:36 ` Joonas Lahtinen
2016-02-15 14:17 ` Peter Zijlstra
2016-02-15 14:17   ` Peter Zijlstra
2016-02-15 17:06   ` Peter Zijlstra
2016-02-15 17:06     ` Peter Zijlstra
2016-02-16  8:49     ` Joonas Lahtinen
2016-02-16  8:49       ` Joonas Lahtinen
2016-02-16  9:14       ` Peter Zijlstra
2016-02-16  9:14         ` Peter Zijlstra
2016-02-16 10:51         ` Joonas Lahtinen
2016-02-16 10:51           ` Joonas Lahtinen
2016-02-16 11:07           ` Peter Zijlstra
2016-02-16 11:07             ` Peter Zijlstra
2016-02-17 12:47             ` Joonas Lahtinen
2016-02-17 12:47               ` Joonas Lahtinen
2016-02-17 14:20               ` Peter Zijlstra
2016-02-17 14:20                 ` Peter Zijlstra
2016-02-17 16:13                 ` Daniel Vetter
2016-02-17 16:13                   ` Daniel Vetter
2016-02-17 16:14                   ` Peter Zijlstra
2016-02-17 16:14                     ` Peter Zijlstra
2016-02-17 16:33                     ` [Intel-gfx] " Daniel Vetter
2016-02-17 16:37                       ` Peter Zijlstra
2016-02-17 16:37                         ` [Intel-gfx] " Peter Zijlstra
2016-02-18 10:39                         ` Joonas Lahtinen [this message]
2016-02-18 10:39                           ` Joonas Lahtinen
2016-02-18 10:54     ` Joonas Lahtinen
2016-02-18 10:54       ` Joonas Lahtinen
2016-02-15 17:18   ` Daniel Vetter
2016-02-15 17:18     ` [Intel-gfx] " Daniel Vetter

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