Date: Sun, 20 Jul 2008 14:48:43 +0200
From: Bernhard Walle <bwalle@suse.de>
To: "Vegard Nossum" <vegard.nossum@gmail.com>
Cc: "Greg KH" <gregkh@suse.de>, "Mariusz Kozlowski" <m.kozlowski@tuxland.pl>,
       "Dave Hansen" <haveblue@us.ibm.com>,
       "Stephen Rothwell" <sfr@canb.auug.org.au>,
       kernel-testers@vger.kernel.org, linux-next@vger.kernel.org,
       LKML <linux-kernel@vger.kernel.org>,
       "Pekka Enberg" <penberg@cs.helsinki.fi>
Subject: Re: linux-next: Tree for July 18: warning at kernel/lockdep.c:2068
 trace_hardirqs_on_caller
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* "Vegard Nossum" <vegard.nossum@gmail.com> [2008-07-20 00:44]:
>
> On Sun, Jul 20, 2008 at 12:27 AM, Vegard Nossum <vegard.nossum@gmail.com> wrote:
> >>> commit 0e3638d1e04040121af00195f7e4628078246489
> >>> Author: Dave Hansen <haveblue@us.ibm.com>
> >>> Date:   Thu Mar 16 17:30:16 2006 -0800
> >>>
> >>>     warn when statically-allocated kobjects are used
> >>>
> >>> ..which only exists in -next. Is that just a truly ancient patch, or
> >>> did somebody forget to adjust their clock?
> >>
> >> It is truely a very old patch, that only lives in my tree, and currently
> >> isn't planned to go to Linus any year soon.
> >>
> >> But it has a very long history of living in the -mm tree, and finding
> >> real bugs, it's just not "safe" enough to go to Linus's tree.  Unless
> >> you think it is?
> >
> > Hm. In this case, the patch is not even reporting a problem, it is in
> > fact in error itself.
> >
> > The problem is that it calls kzalloc() before the slab caches have
> > been set up. (Yes, it's a wonder that nothing crashed.) I can only
> > suggest the addendum
> >
> >    if (!slab_is_available())
> >        return;
> 
> Well, of course, it's also possible that the e820 code shouldn't be
> initializing kobjects this early in the first place.
> 
> firmware_map_add_early() is using bootmem for the allocation. So yes,
> I guess it should possible to use kobjects here. That said, this code
> is in fact fairly recent:
> 
> commit 69ac9cd629ca96e59f34eb4ccd12d00b2c8276a7
> Author: Bernhard Walle <bwalle@suse.de>
> Date:   Fri Jun 27 13:12:54 2008 +0200
> 
>     sysfs: add /sys/firmware/memmap
> 
> I'll add the Cc. I still have a feeling that the kobject patch should
> expect to run even when slab is not available.

I already posted a fix for that problem, see
http://article.gmane.org/gmane.linux.kernel.kexec/1882.

Which people should I CC to get that fix into linux-next?


Bernhard
-- 
Bernhard Walle, SUSE LINUX Products GmbH, Architecture Development
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