linux-kernel - Re: [PATCH] lockdep: increase static allocations

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Message-ID: <20140109085631.GC7572@laptop.programming.kicks-ass.net>
Date:	Thu, 9 Jan 2014 09:56:31 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Sasha Levin <sasha.levin@...cle.com>, mingo@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lockdep: increase static allocations

On Thu, Jan 09, 2014 at 12:23:22AM +0100, Andi Kleen wrote:
> On Wed, Jan 08, 2014 at 03:10:55PM -0500, Sasha Levin wrote:
> > On 01/08/2014 02:51 PM, Andi Kleen wrote:
> > >Sasha Levin <sasha.levin@...cle.com> writes:
> > >
> > >>Fuzzing a recent kernel with a large configuration hits the static
> > >>allocation limits and disables lockdep.
> > >
> > >Doesn't that use a lot more memory?  I thought lockdep preallocates.
> > >
> > >Doubling may be too aggressive.
> > 
> > The patch adds about 4MB of memory usage, I didn't think it's too much for something
> > that is only enabled during debugging.
> 
> Wasting 4MB is an issue.
> 
> Linus' first Linux system had less total memory than that.

Meh.. if someone from the embedded people care we can add
CONFIG_BASE_SMALL option, until then I couldn't care less about 4m.

> > 
> > If this is an issue, can I suggest making these values configurable in the .config
> > and just let users pick whatever they want?
> 
> Better allocate it at boot time, using a boot parameter or somesuch.

wrongbot andi is at it again.. no that's far too late.
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