linux-kernel - Re: S3 resume regression [1cf4f629d9d2 ("cpu/hotplug: Move online calls to hotplugged cpu")]

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Message-ID: <20160518072424.GU4329@intel.com>
Date:	Wed, 18 May 2016 10:24:24 +0300
From:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-arch@...r.kernel.org, Rik van Riel <riel@...hat.com>,
	"Srivatsa S. Bhat" <srivatsa@....edu>,
	Peter Zijlstra <peterz@...radead.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Paul Turner <pjt@...gle.com>, linux-kernel@...r.kernel.org,
	rui.zhang@...el.com, len.brown@...el.com,
	Linux PM <linux-pm@...r.kernel.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>
Subject: Re: S3 resume regression [1cf4f629d9d2 ("cpu/hotplug: Move online
 calls to hotplugged cpu")]

On Wed, May 18, 2016 at 01:14:42AM +0200, Rafael J. Wysocki wrote:
> On 5/16/2016 9:39 PM, Ville Syrjälä wrote:
> > On Wed, May 11, 2016 at 04:34:06PM +0300, Ville Syrjälä wrote:
> >> On Wed, May 11, 2016 at 08:44:45AM -0400, Steven Rostedt wrote:
> >>> On Wed, 11 May 2016 15:21:16 +0300
> >>> Ville Syrjälä <ville.syrjala@...ux.intel.com> wrote:
> >>>
> >>>> Yeah can't get anything from the machine at that point. netconsole
> >>>> didn't help either, and no serial on this machine. And IIRC I've
> >>>> tried ramoops on this thing in the past but unfortunately the memory
> >>>> got cleared on reboot.
> >>>>
> >>> Can you look at the documentation in the kernel code at
> >>>
> >>> Documentation/power/basic-pm-debugging.txt And follow the procedures
> >>> for testing suspend to RAM (although it requires mostly running the
> >>> same tests as for hibernation suspending).
> >>>
> >>> You can also use the tool s2ram for this as well.
> >>>
> >>> See Documentation/power/s2ram.txt
> >>>
> >>> Perhaps this can give us a bit more light onto the problem.
> >>>
> >>> Basically the above does partial suspend and resume, and can pinpoint
> >>> problem areas down to a more select location.
> >> All the pm_test modes work fine. The only difference between them was
> >> that 'platform' required me to manually wake up the machine (hitting a
> >> key was sufficient), whereas the others woke up without help.
> >>
> >> pm_trace gave me
> >> [    1.306633]   Magic number: 0:185:178
> >> [    1.322880]   hash matches ../drivers/base/power/main.c:1070
> >> [    1.339270] acpi device:0e: hash matches
> >> [    1.355414]  platform: hash matches
> >>
> >> which is the TRACE_SUSPEND in __device_suspend_noirq(), so no help
> >> there.
> >>
> >> I guess I could try to sprinkle more TRACE_RESUMEs around into some
> >> early resume code. If anyone has good ideas where to put them it
> >> might speed things up a bit.
> > So I did a bunch of that and found that it gets stuck somewhere
> > around executing the _WAK method:
> > platform_resume_noirq
> >   acpi_pm_finish
> >    acpi_leave_sleep_state
> >     acpi_hw_sleep_dispatch
> >      acpi_hw_legacy_wake
> >       acpi_hw_execute_sleep_method
> >        acpi_evaluate_object
> >         acpi_ns_evaluate
> >          acpi_ps_execute_method
> >           acpi_ps_parse_aml
> >
> > It also seesm that adding a few TRACE_RESUME()s or an msleep() right
> > after enable_nonboot_cpus() can avoid the hang, sometimes.
> >
> > I've attached the DSDT in case anyone is interested in looking at it.
> >
> 
> What if you comment out the execution of _WAK (line 318 of 
> drivers/acpi/acpica/hwsleep.c in 4.6)?  Does that make any difference?

Indeed it does. Tried with acpi_idle and intel_idle, and both appear to
resume just fine with that hack.

-       acpi_hw_execute_sleep_method(METHOD_PATHNAME__WAK, sleep_state);
+       //acpi_hw_execute_sleep_method(METHOD_PATHNAME__WAK, sleep_state);
+       printk(KERN_CRIT "skipping _WAK\n");

-- 
Ville Syrjälä
Intel OTC