linux-kernel - Re: oprofile + hibernation = badness

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Date:	Tue, 19 Aug 2008 03:13:38 +0200
From:	Andi Kleen <ak@...ux.intel.com>
To:	Vegard Nossum <vegard.nossum@...il.com>
CC:	Pavel Machek <pavel@...e.cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Robert Richter <robert.richter@....com>,
	Ingo Molnar <mingo@...e.hu>,
	Philippe Elie <phil.el@...adoo.fr>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: oprofile + hibernation = badness


> 
> These keep on coming all through the suspend/shutdown sequence, also
> intermixing with other messages. I'm guessing oprofile is trying to
> NMI CPUs that have been brought down?

That should actually work in theory. Linux CPU offlining puts CPUs in a state where
they can still process NMIs. Hmm actually there was a change recently to free
their exception stacks. Maybe it's broken now.

Also oprofile has a suspend method that disables NMIs.

> Now I get some ACPI Exceptions, but I think that these are unrelated
> to starting oprofile, because I have seen them on regular shutdowns as
> well:
> 
> PM: Syncing filesystems ... done.
> Freezing user space processes ... (elapsed 0.00 seconds) done.
> Freezing remaining freezable tasks ... (elapsed 0.00 seconds) done.
> PM: Shrinking memory... done (0 pages freed)
> PM: Freed 0 kbytes in 0.44 seconds (0.00 MB/s)
> Suspending console(s) (use no_console_suspend to debug)
> ACPI Exception (exoparg2-0444): AE_AML_PACKAGE_LIMIT, Index
> (000000007) is beyond end of object [20080609]
> ACPI Error (psparse-0530): Method parse/execution failed
> [\_SB_.PCI0.IDE0.GTM_] (Node f783bfc0), AE_AML_PACKAGE_LIMIT
> ACPI Error (psparse-0530): Method parse/execution failed
> [\_SB_.PCI0.IDE0.CHN0._GTM] (Node f783bb40), AE_AML_PACKAGE_LIMIT
> ACPI handle has no context!
> serial 00:0d: disabled
> serial 00:06: disabled
> ehci_hcd 0000:00:1d.7: PCI INT A disabled
> uhci_hcd 0000:00:1d.3: PCI INT D disabled
> uhci_hcd 0000:00:1d.2: PCI INT C disabled
> uhci_hcd 0000:00:1d.1: PCI INT B disabled
> uhci_hcd 0000:00:1d.0: PCI INT A disabled
> ACPI: Preparing to enter system sleep state S4
> 
> After that, I see the message "WQ on CPU0, prefer CPU1" a few times.
> This must also be bad.
> 
> Now some warnings:
> 
> ------------[ cut here ]------------
> WARNING: at /uio/arkimedes/s29/vegardno/git-working/linux-2.6/kernel/smp.c:328 s
> mp_call_function_mask+0x194/0x1a0()

The usual problem: the suspend function when interrupts are
already disabled calls smp_call_function which is not allowed with
interrupt off. But at this point all the other CPUs should be already
down anyways, so it should be enough to just drop that.

This patch should fix that problem at least by fixing cpu hotplug&
suspend support. Untested.

-Andi


View attachment "0001-oprofile-fix-cpu-hotcplug.patch" of type "text/plain" (2590 bytes)