linux-kernel - Re: Bug: ACPI, scheduling while atomic (was Re: [PATCH 0/4] sched: Make sleep inside atomic detection work on !PREEMPT)

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Message-ID: <20110926225417.GS2399@linux.vnet.ibm.com>
Date:	Mon, 26 Sep 2011 15:54:17 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Davidlohr Bueso <dave@....org>
Cc:	Randy Dunlap <rdunlap@...otime.net>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>, Len Brown <lenb@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: Bug: ACPI, scheduling while atomic (was Re: [PATCH 0/4] sched:
 Make sleep inside atomic detection work on !PREEMPT)

On Mon, Sep 26, 2011 at 07:33:34PM -0300, Davidlohr Bueso wrote:
> On Wed, 2011-08-24 at 20:57 -0700, Randy Dunlap wrote:
> > On Thu, 9 Jun 2011 00:49:41 +0200 Frederic Weisbecker wrote:
> > 
> > > On Wed, Jun 08, 2011 at 07:48:31PM +0200, Frederic Weisbecker wrote:
> > > > Aside it may mostly avoid the need for a specific PROVE_RCU
> > > > check when we sleep inside an rcu read side critical section.
> > > > 
> > > > Better make sleeping inside atomic sections work everywhere.
> > > 
> > > BTW, it has led to detect a bug in the ACPI code. It happens in
> > > !CONFIG_PREEMPT:
> > > 
> > > [    0.160187] BUG: scheduling while atomic: swapper/0/0x10000002
> > > [    0.166016] no locks held by swapper/0.
> > > [    0.170014] Modules linked in:
> > > [    0.173107] Pid: 0, comm: swapper Not tainted 2.6.39+ #124
> > > [    0.180014] Call Trace:
> > > [    0.182481]  [<ffffffff81048685>] __schedule_bug+0x85/0x90
> > > [    0.187967]  [<ffffffff817da98c>] schedule+0x75c/0xa40
> > > [    0.190022]  [<ffffffff8109a1fd>] ? trace_hardirqs_on+0xd/0x10
> > > [    0.200023]  [<ffffffff813879c0>] ? acpi_ps_free_op+0x22/0x24
> > > [    0.205776]  [<ffffffff810554a5>] __cond_resched+0x25/0x40
> > > [    0.210022]  [<ffffffff817daf3b>] _cond_resched+0x2b/0x40
> > > [    0.215420]  [<ffffffff81386cbe>] acpi_ps_complete_op+0x262/0x278
> > > [    0.220023]  [<ffffffff813874df>] acpi_ps_parse_loop+0x80b/0x960
> > > [    0.230023]  [<ffffffff81386607>] acpi_ps_parse_aml+0x98/0x274
> > > [    0.235859]  [<ffffffff81384cbb>] acpi_ns_one_complete_parse+0x103/0x120
> > > [    0.240021]  [<ffffffff810886da>] ? up+0x2a/0x50
> > > [    0.244641]  [<ffffffff81384cf3>] acpi_ns_parse_table+0x1b/0x34
> > > [    0.250022]  [<ffffffff8138242a>] acpi_ns_load_table+0x4a/0x8c
> > > [    0.260023]  [<ffffffff8138947c>] acpi_load_tables+0x9c/0x15d
> > > [    0.265774]  [<ffffffff81d0b0f8>] acpi_early_init+0x6c/0xf7
> > > [    0.270022]  [<ffffffff81cd8d31>] start_kernel+0x400/0x415
> > > [    0.275508]  [<ffffffff81cd8346>] x86_64_start_reservations+0x131/0x135
> > > [    0.280022]  [<ffffffff81cd844d>] x86_64_start_kernel+0x103/0x112
> > > 
> > > ACPI_PREEMPTION_POINT() is called from acpi_ps_complete_op() and schedules
> > > if !PREEMPT. But preemption is disabled as we are in early bootup.
> > 
> > This still happens in 3.1-rc[123].
> > Was there a patch for it?
> > 
> 
> And still in -rc7. I was looking at Paul's github
> (https://github.com/paulmckrcu/linux/) but can't find it.

I just updated this with Frederic's new patch series.  Or do you mean
that you can't access my github tree at all?

							Thanx, Paul
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