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Message-Id: <200911092103.54083.rjw@sisk.pl>
Date: Mon, 9 Nov 2009 21:03:54 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>,
LKML <linux-kernel@...r.kernel.org>,
pm list <linux-pm@...ts.linux-foundation.org>,
Greg KH <gregkh@...e.de>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: Help needed: Resume problems in 2.6.32-rc, perhaps related to preempt_count leakage in keventd
On Monday 09 November 2009, Thomas Gleixner wrote:
> On Mon, 9 Nov 2009, Rafael J. Wysocki wrote:
> > On Monday 09 November 2009, Mike Galbraith wrote:
> > > On Mon, 2009-11-09 at 16:47 +0100, Rafael J. Wysocki wrote:
> > > > On Monday 09 November 2009, Mike Galbraith wrote:
> > >
> > > > > > Very likely. What did you do to fix it?
> > > > >
> > > > > You don't really wanna know. In 31 with newidle enabled, the below
> > > > > fixed it. It won't fix 32, though it might cure the resume problem.
> > > >
> > > > OK, I'll give it a try.
> >
> > It doesn't help.
> >
> > Also, I can reproduce the issue with current -git and kernel preepmtion
> > disabled.
> >
> > > I just tried to trigger badness via high speed online/offline combined
> > > with taskset with CONFIG_PREEMPT enabled, and couldn't make it explode.
> >
> > I'm not able to do it this way too, so resume seems to be necessary to trigger
> > it. I'm going try with the suspend debug in the "core" mode.
> >
> > > (damn, wish i could s2ram this box)
> >
> > That need not suffice. I have two other boxes that suspend and resume
> > correctly with 2.6.32-rc, AFAICS.
> >
> > However, there seems to be a systematic error somewhere, since the failure
> > always happens at the same place, ie. list_del_init(cwq->worklist.next); in
> > run_workqueue(), in preemptible as well as in non-preemptible kernels.
> >
> > Which is kind of strange, given the !list_empty(&cwq->worklist) test right
> > before it.
>
> Hmm, no. list_empty() just tells you whether the list is empty or
> not. It does not care whether the list is corrupted or not. Have you
> tried to run with list debugging enabled ?
I did, but the result was exactly the same as without it.
Also, I don't seem to be able to reproduce the issue without actually
suspending the box. I tried with offlining/onlining CPU1 and with
the /sys/power/pm_test "core" test and it didn't show up.
Thanks,
Rafael
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