linux-kernel - Re: Possible Oprofile crash/race when stopping

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Date:	Tue, 03 Aug 2010 11:39:33 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Robert Richter <robert.richter@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Carl E. Love" <cel@...ibm.com>,
	Michael Ellerman <michaele@....ibm.com>
Subject: Re: Possible Oprofile crash/race when stopping


> Benjamin,
> 
> thanks for reporting this. I was trying to reproduce this with various
> loads and scenarios, but without success so far. Can you give me a
> hint of the load you have (number of processes running, cpu load, do
> you switch off oprofile while many processes are still running)? Are
> you able to regularly trigger it?

Hi, sorry, I missed your reply, Michael just gave me a wake-up call.

I can't tell that much about the workload, I don't have access to it
either, let's say that from my point of view it's a "customer" binary
blob.

I can re-trigger it though.

> > I think the right sequence however requires breaking up end_sync. Ie, we
> > need to do in that order:
> > 
> >   - cancel the workqueues
> >   - unregister the notifier
> >   - process the mortuary
> > 
> > What do you think ?
> 
> This could potentially fix it, I will have to look deeper into the
> code. Try to do this next week.

Thanks. Let me know.

Cheers,
Ben.


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