Date: Fri, 10 Jul 2009 11:03:51 +0200
From: Nick Piggin <npiggin@suse.de>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Ingo Molnar <mingo@elte.hu>, Janboe Ye <yuan-bo.ye@motorola.com>,
       linux-kernel@vger.kernel.org, vegard.nossum@gmail.com,
       graydon@redhat.com, fche@redhat.com, cl@linux-foundation.org
Subject: Re: [RFC][PATCH] Check write to slab memory which freed already using mudflap
Message-ID: <20090710090351.GD14666@wotan.suse.de>
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On Fri, Jul 10, 2009 at 11:52:00AM +0300, Pekka Enberg wrote:
> Hi Ingo,
> 
> On Fri, 2009-07-10 at 10:47 +0200, Ingo Molnar wrote:
> > > >  arch/arm/include/asm/elf.h |    1 +
> > > >  arch/arm/kernel/module.c   |    1 +
> > > >  drivers/Makefile           |    4 +-
> > > >  include/mf-runtime.h       |   42 ++++++++++++++
> > > >  kernel/Makefile            |    2 +-
> > > >  kernel/mudflap.c           |  132 ++++++++++++++++++++++++++++++++++++++++++++
> > > >  lib/Kconfig.debug          |    7 ++
> > > >  mm/slab.c                  |   53 ++++++++++++++++++
> > > >  8 files changed, 240 insertions(+), 2 deletions(-)
> > > 
> > > SLAB is (slowly) going away so you might want to port this to SLUB 
> > > as well so we can merge both.
> > 
> > and SLQB which will replace both? :-/
> 
> Well, I cannot really expect people to port patches to SLQB until it's
> in mainline.

I agree...

slab allocator's primary metric is performance, and debugging
features can tend to be added very easily after that (because
there is a performance hit accepted). So I have not been spending
much time on those in SLQB.

If it gets merged and decided to stay based on performance results,
then I will do more to port over other debug features.


> And whether SQLB will replace SLUB remains to be seen.
> We're still fixing minor issues here and there in SLUB so I have no
> reason to expect SLQB stabilization to happen overnight which means
> we're going to have SLUB in the tree for a while anyway.

I think it's pretty good now. It was the right thing not to merge
it in this window (seeing as I'd forgotten to make it the default
in -next). And that flushed out a bug or two. The core logic I
think is pretty solid now though.

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