linux-kernel - Re: latest -git: hibernate: possible circular locking dependency detected

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Date:	Thu, 21 Aug 2008 21:31:29 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"Vegard Nossum" <vegard.nossum@...il.com>
Cc:	"Dmitry Adamushko" <dmitry.adamushko@...il.com>,
	"Max Krasnyanskiy" <maxk@...lcomm.com>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
	"Pavel Machek" <pavel@....cz>
Subject: Re: latest -git: hibernate: possible circular locking dependency detected

On Thursday, 21 of August 2008, Vegard Nossum wrote:
> On Thu, Aug 21, 2008 at 9:07 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > On Thursday, 21 of August 2008, Vegard Nossum wrote:
> >> On Thu, Aug 21, 2008 at 8:31 PM, Vegard Nossum <vegard.nossum@...il.com> wrote:
> >> > On Thu, Aug 21, 2008 at 8:22 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> >> >> On Thursday, 21 of August 2008, Vegard Nossum wrote:
> >> >>>
> >> >>> I just got this on v2.6.27-rc4 (+ unrelated fix):
> >> >>>
> >> >>> ACPI: Preparing to enter system sleep state S5
> >> >>
> >> >> This looks fishy.
> >> >>
> >> >> Please check what's there in /sys/power/disk .
> >> >>
> >>
> >> Sorry, forgot this one:
> >>
> >> # cat /sys/power/disk
> >> test testproc [shutdown] reboot
> >
> > Hm, I wonder why 'platform' isn't there.
> >
> > Perhaps the dmesg log will tell.
> >
> > [/me looks]
> >
> > No, it doesn't.  The BIOS evidently supports S4.
> >
> > [/me looks into the source code]
> >
> > I have no idea whatsoever how it is possible to have
> >
> > "ACPI: (supports S0 S1 S3 S4 S5)"
> >
> > in the log and not to have "platform" in the output of "cat /sys/power/disk".
> 
> I'm sorry, I made a stupid mistake: That file was taken from the
> system when it was booted with acpi=off. The boot log had acpi
> enabled, of course. Here is the same file (now booted without
> acpi=off):
> 
> # cat /sys/power/disk
> [platform] test testproc shutdown reboot
> 
> > Can you please add
> >
> > printk(KERN_CRIT "PM: hibernation_ops = %p\n", hibernation_ops);
> >
> > at the end of kernel/power/disk.c:hibernation_set_ops() and see if it gets
> > printed during boot?
> 
> I guess this is now not necessary anymore?

No, it's not.

Now, what is the source of the "SysRq : Power Off" in the dmesg you posted?

Also, have you tried to hibernate with the "platform" setting selected in
"cat /sys/power/disk" and if you have, does the lockdep warning appear in this
case?

Rafael

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