linux-kernel - Re: lockdep and oops_in

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Message-ID: <1280995849.1923.1515.camel@laptop>
Date:	Thu, 05 Aug 2010 10:10:49 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Dave Airlie <airlied@...il.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: lockdep and oops_in_progress

On Thu, 2010-08-05 at 16:21 +1000, Dave Airlie wrote:
> Hi guys,
> 
> I was debugging a wierd issue with suspend/resume and fbcon/X with
> some recent work Jesse and myself did to try and make sure a pinned
> fbcon always gets the text on it with a panic or oops occurs.
> 
> It does this by testing the oops_in_progress flag, however once any
> lockdep issue occurs it looks to me that we leave this flag set
> forever, in most places I can see in oops code etc they call
> bust_spinlocks(1) then bust_spinlocks(0) to balance the
> oops_in_progress value, but lockdep never seems to reset it.
> 
> I'm wondering if there is an inherent reason for this or if I whip up
> a patch to reset once the lockdep is printed if this would cause any
> issues?

That's debug_locks_off(), right? I don't think there's a particular
reason we keep it set, cleaning that up might take a bit of work but
shouldn't be too hard.

Ingo, do you remember anything about that?, I think that bit comes from
before my time.
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