Re: 2.6.30: hibernation/swsusp lockup due to acpi-cpufreq

["Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>]

On Tue, 2009-06-16 at 14:09 -0700, Andrew Morton wrote:
> On Tue, 16 Jun 2009 22:40:39 +0200
> Johannes Stezenbach <js@sig21.net> wrote:
> 
> > On Tue, Jun 16, 2009 at 01:25:58PM -0700, Pallipadi, Venkatesh wrote:
> > >
> > > Can you try the patch below (your changes + a warnon). That should give
> > > the stack trace with successful suspend-resume.
> > >
> > > acpi-cpufreq will not directly disable interrupt and call these routines.
> > > So, it will be interesting to see how we are ending up in this state.
> >
> > Yes, I actually had the same idea and just did it ;-)
> > I also found this:
> > http://lkml.org/lkml/2007/7/17/674
> >
> > ------------[ cut here ]------------
> > WARNING: at kernel/up.c:18 smp_call_function_single+0x45/0x60()
> > Hardware name: 2373Y4M
> > Modules linked in: ath5k mac80211 cfg80211 uhci_hcd ehci_hcd
> > Pid: 4139, comm: bash Not tainted 2.6.30 #8
> > Call Trace:
> >  [<c011ea0d>] warn_slowpath_common+0x60/0x90
> >  [<c010d86c>] ? do_drv_read+0x0/0x31
> >  [<c011ea4a>] warn_slowpath_null+0xd/0x10
> >  [<c013acc1>] smp_call_function_single+0x45/0x60
> >  [<c010d4e5>] get_cur_val+0x62/0x6c
> >  [<c010d72f>] get_cur_freq_on_cpu+0x35/0x58
> >  [<c03786e9>] cpufreq_suspend+0x76/0xd9
> >  [<c0136c3b>] ? clockevents_notify+0x1e/0x68
> >  [<c02ff570>] sysdev_suspend+0x4e/0x182
> >  [<c013fd28>] hibernation_snapshot+0x89/0x16b
> >  [<c013fe99>] hibernate+0x8f/0x147
> >  [<c013ec82>] ? state_store+0x0/0xa2
> >  [<c013ecd7>] state_store+0x55/0xa2
> >  [<c013ec82>] ? state_store+0x0/0xa2
> >  [<c024dff5>] kobj_attr_store+0x1a/0x22
> >  [<c01a7164>] sysfs_write_file+0xb4/0xdf
> >  [<c01a70b0>] ? sysfs_write_file+0x0/0xdf
> >  [<c0170cf2>] vfs_write+0x8a/0x12c
> >  [<c0170e2d>] sys_write+0x3b/0x60
> >  [<c01028f4>] sysenter_do_call+0x12/0x26
> > ---[ end trace 1c2172bce3982a59 ]---
> 
> Right, so it's the suspend-must-disable-local-interrupts thing.  Again.
>  create_image()'s local_irq_disable().
> 
> It was wrong to call work_on_cpu() with lcoal interrupts disabled, and
> it's now wrong to call smp_call_function_single() with local interrupts
> disabled.  It's just that smp_call_function_single() warns while
> work_on_cpu() didn't.
> 
> That all explains the warning But afaik we still don't know why your
> machine actually failed.  Perhaps it is a side-efect of emitting the
> warning when the console is in a weird state?
> 
> So..  what to do?  Possibly we could hack cpufreq to not use
> smp_call_function_single() if the call is to be done on the local CPU. 
> But SMP might still be broken - if it really does want to do a cross-cpu
> call.

We surely do not need cross CPU cal at this point as all secondary cpus
will be offline at this point.

> Why does cpufreq need to do a cross-CPU get_cur_freq_on_cpu() call at
> suspend time _anyway_?  Surely cpufreq knows the target CPU's frequency
> from its internal in-main-memory state?

That was what I was wondering as well. Looks like this part of
cpufreq_suspend came from

commit 42d4dc3f4e1ec1396371aac89d0dccfdd977191b
Author: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date:   Fri Apr 29 07:40:12 2005 -0700

    [PATCH] Add suspend method to cpufreq core
    
    In order to properly fix some issues with cpufreq vs. sleep on
    PowerBooks, I had to add a suspend callback to the pmac_cpufreq
driver.
    I must force a switch to full speed before sleep and I switch back
to
    previous speed on resume.
    
    I also added a driver flag to disable the warnings in suspend/resume
    since it is expected in this case to have different speed (and I
want it
    to fixup the jiffies properly).
    
    Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Signed-off-by: Andrew Morton <akpm@osdl.org>
    Signed-off-by: Linus Torvalds <torvalds@osdl.org>



benh: Do you think we still need this cpufreq_driver->get() and return
error on (!cur_freq || !cpu_policy->cur) stuff?
May be we should all the checks only if CPUFREQ_PM_NO_WARN is set?

Thanks,
Venki