Re: lockdep and debug objects together are broken?

From: Vegard Nossum
Date: Tue Jan 20 2009 - 16:12:00 EST


On Tue, Jan 20, 2009 at 9:55 AM, Nick Piggin <npiggin@xxxxxxx> wrote:
> Hi,
>
> I've had a problem frustrating my testing because lockdep was silently turning
> itself off... I patched out the code to disable lockdep after the first error,
> and it started showing up weird errors. kernel/fork.c:990 seemed to be the
> first to trigger (hard irqs disabled) from a call_usermodehelper call. Later,
> migration thread was reported to try to unlock rq->lock although it was
> holding no locks. Then init was reported to return to userspace without
> releasing an objectdebug hash lock.
>
> All that went away and everything seemed to work properly with debug objects
> configured out.
>
> I didn't get too far in trying to debug the problem. But it should be easy
> enough to reproduce (if not, I can post traces or test patches).

I just built a kernel with lockdep and debugobjects enabled, and
everything seemed fine. I think you should post your kernel version,
config, and the lockdep patch (if needed -- it didn't seem to turn
itself off here).


Vegard

--
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
-- E. W. Dijkstra, EWD1036
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