Subject: Re: Major slab mem leak with 2.6.17 / GCC 4.1.1
From: Mike Galbraith <efault@gmx.de>
To: nmeyers@vestmark.com
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <20061013105502.GA9773@viviport.com>
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	 <1160727912.15431.11.camel@Homer.simpson.net>
	 <20061013105502.GA9773@viviport.com>
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Date: Fri, 13 Oct 2006 21:28:15 +0000
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On Fri, 2006-10-13 at 06:55 -0400, nmeyers@vestmark.com wrote:
> On Fri, Oct 13, 2006 at 08:25:12AM +0000, Mike Galbraith wrote:
> > On Thu, 2006-10-12 at 20:49 -0400, nmeyers@vestmark.com wrote:
> > 
> > > I tried Catalin Marinas' kmemleak patches, and had to rebuild with
> > > GCC 3.4.6 because of a 4.1.1 compiler bug that prevents compilation
> > > of the patches.
> > 
> > Yeah, seems any remotely recent gcc hates it.  That puts a rather large
> > dent in usability.
> > 
> > > And... building with 3.4.5 fixed the leak! So I guess I have very little
> > > detail to report - except that there's a nasty leak in 2.6.17 when built
> > > with 4.1.1.
> > 
> > If you build using 3.4.5 _without_ the kmemleak patches, do you see the
> > leak again?  (ie is kmemleak altering timing, or is kernel miscompiled)
> 
> I wondered the same thing. I went back to the original source and .config
> - rebuilding with 3.4.6 (3.4.5 is a typo) fixed the leak.

Hmm.  That leaves us with a 4.1.1 miss-compile maybe.
 
> > > If anyone has a version of kmemleak that I can build with 4.1.1, or
> > > any other suggestions for instrumentation, I'd be happy to gather more
> > > data - the problem is very easy for me to reproduce.
> > 
> > I can only suggest trying latest/greatest to see if the issue is still
> > present, and if so, try to find a way that others may trigger it.
> 
> I may just do that - apparently 4.1.2 is supposed to fix the kmemleak
> compile problem. My (admittedly lazy) inclination is to wait until that
> comes out in a Gentoo ebuild.

I think some re-evaluation is needed.

(fwiw, I tried a pre-release 4.1.2 compiler, and it still choked... I
didn't even look, so salt to taste)

	-Mike

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