From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
xen-devel@lists.xensource.com,
julie Sullivan <kernelmail.jms@gmail.com>,
linux-kernel@vger.kernel.org, chengxu@linux.vnet.ibm.com,
kulkarni.ravi4@gmail.com
Subject: Re: PROBLEM: 3.0-rc kernels unbootable since -rc3 - under Xen, 32-bit guest only.
Date: Tue, 12 Jul 2011 09:46:20 -0700 [thread overview]
Message-ID: <20110712164620.GG2326@linux.vnet.ibm.com> (raw)
In-Reply-To: <20110712163210.GB1186@dumpdata.com>
On Tue, Jul 12, 2011 at 12:32:10PM -0400, Konrad Rzeszutek Wilk wrote:
> > > > > http://darnok.org/xen/cpu1.log
> > > >
> > > > OK, a fair amount of variety, then lots and lots of task_waking_fair(),
> > > > so I still feel good about asking you for the following.
> > >
> > > But... But... But...
> > >
> > > Just how accurate are these stack traces? For example, do you have
> > > frame pointers enabled? If not, could you please enable them?
>
> Frame pointers are enabled.
> > >
> > > The reason that I ask is that the wakeme_after_rcu() looks like it is
> > > being invoked from softirq, which would be grossly illegal and could
> > > cause any manner of misbehavior. Did someone put a synchronize_rcu()
> > > into an RCU callback or something? Or did I do something really really
>
> This is a 3.0-rc6 based kernels with the debug patch, the initial
> RCU inhibit patch (where you disable the RCU checking during bootup) and
> that is it.
>
> What is bizzare is that the soft_irq shows but there is no corresponding
> Xen eventchannel stack trace - there should have been also xen_evtchn_upcall
> (which is the general code that calls the main IRQ handler.. which would make
> the softirq call). This is assuming that the IRQ (timer one) is reguarly dispatching
> (which it looks to be doing). Somehow getting just the softirq by itself is bizzre.
>
> Perhaps an IPI has been sent that does this. Let me see what a stack
> trace for an IPI looks like.
Thank you for the info!
> > > braindead inside the RCU implementation?
> > >
> > > (I am looking into this last question, but would appreciate any and all
> > > help with the other questions!)
> >
> > OK, I was confusing Julie's, Ravi's, and Konrad's situations.
>
> Do you want me to create a new email thread to keep this one seperate?
Let's please keep everyone on copy. I bet that these problems are
related. Plus once we get something that works, it would be good if
everyone could test it.
> > The wakeme_after_rcu() is in fact OK to call from sofirq -- if and
> > only if the scheduler is actually running. This is what happens if
> > you do a synchronize_rcu() given your CONFIG_TREE_RCU setup -- an RCU
> > callback is posted that, when invoked, awakens the task that invoked
> > synchronize_rcu().
> >
> > And, based on http://darnok.org/xen/log-rcu-stall, Konrad's system
> > appears to be well past the point where the scheduler is initialized.
> >
> > So I am coming back around to the loop in task_waking_fair().
> >
> > Though the patch I sent out earlier might help, for example, if early
> > invocation of RCU callbacks is somehow messing up the scheduler's
> > initialization.
>
> Ok, let me try it out.
Thank you again!
Thanx, Paul
next prev parent reply other threads:[~2011-07-12 16:46 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-06 21:10 PROBLEM: 3.0-rc kernels unbootable since -rc3 julie Sullivan
2011-07-06 21:23 ` Paul E. McKenney
2011-07-07 19:31 ` Paul E. McKenney
2011-07-07 19:47 ` julie Sullivan
2011-07-07 19:58 ` Paul E. McKenney
2011-07-07 20:28 ` julie Sullivan
2011-07-07 20:47 ` julie Sullivan
2011-07-08 0:29 ` Paul E. McKenney
2011-07-09 10:09 ` Paul E. McKenney
2011-07-10 0:45 ` julie Sullivan
2011-07-10 3:25 ` Paul E. McKenney
2011-07-10 16:38 ` julie Sullivan
2011-07-10 17:16 ` Paul E. McKenney
2011-07-10 17:35 ` Paul E. McKenney
2011-07-10 20:30 ` julie Sullivan
2011-07-10 21:46 ` Paul E. McKenney
2011-07-10 21:50 ` julie Sullivan
2011-07-10 23:14 ` Paul E. McKenney
2011-07-11 16:24 ` Konrad Rzeszutek Wilk
2011-07-11 17:13 ` Paul E. McKenney
2011-07-11 19:30 ` Konrad Rzeszutek Wilk
2011-07-11 20:15 ` Paul E. McKenney
2011-07-11 21:09 ` Konrad Rzeszutek Wilk
2011-07-12 10:55 ` Paul E. McKenney
2011-07-12 14:12 ` Konrad Rzeszutek Wilk
2011-07-12 14:49 ` Paul E. McKenney
2011-07-12 15:07 ` Paul E. McKenney
2011-07-12 15:15 ` Paul E. McKenney
2011-07-12 15:22 ` Paul E. McKenney
2011-07-12 16:32 ` PROBLEM: 3.0-rc kernels unbootable since -rc3 - under Xen, 32-bit guest only Konrad Rzeszutek Wilk
2011-07-12 16:46 ` Paul E. McKenney [this message]
2011-07-12 16:03 ` PROBLEM: 3.0-rc kernels unbootable since -rc3 Konrad Rzeszutek Wilk
2011-07-12 16:39 ` Paul E. McKenney
2011-07-12 18:01 ` Konrad Rzeszutek Wilk
2011-07-12 18:59 ` Paul E. McKenney
2011-07-12 19:07 ` Konrad Rzeszutek Wilk
2011-07-12 20:52 ` Paul E. McKenney
2011-07-12 19:10 ` Peter Zijlstra
2011-07-12 19:57 ` Konrad Rzeszutek Wilk
2011-07-12 20:46 ` Paul E. McKenney
2011-07-12 21:04 ` Julie Sullivan
2011-07-12 21:07 ` Paul E. McKenney
2011-07-12 20:05 ` Paul E. McKenney
2011-07-12 6:33 ` [Xen-devel] " Sander Eikelenboom
2011-07-12 14:05 ` Paul E. McKenney
[not found] ` <CAAVPGOMSprJSkzziH6hJv9PweOONzsMaRZEK2ZSrV3xFBReTPw@mail.gmail.com>
[not found] ` <20110711214301.GP2245@linux.vnet.ibm.com>
2011-07-12 21:15 ` Julie Sullivan
2011-07-12 21:29 ` Paul E. McKenney
2011-07-12 21:35 ` Julie Sullivan
2011-07-12 21:49 ` Julie Sullivan
2011-07-12 22:00 ` Paul E. McKenney
2011-07-13 7:18 ` RKK
2011-07-13 15:47 ` Paul E. McKenney
2011-07-13 20:57 ` Julie Sullivan
2011-07-13 21:23 ` Paul E. McKenney
2011-07-07 17:28 ` julie Sullivan
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