linux-kernel - Re: [PATCH] slab+slob: dup name string

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Message-ID: <1337773595.3013.15.camel@dabdike.int.hansenpartnership.com>
Date:	Wed, 23 May 2012 12:46:35 +0100
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Christoph Lameter <cl@...ux.com>,
	Glauber Costa <glommer@...allels.com>,
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	linux-mm@...ck.org, Pekka Enberg <penberg@...helsinki.fi>
Subject: Re: [PATCH] slab+slob: dup name string

On Tue, 2012-05-22 at 15:31 -0700, David Rientjes wrote:
> On Tue, 22 May 2012, Christoph Lameter wrote:
> 
> > > I think that's precisely David's point: that we might want to destroy them
> > > eventually.
> > 
> > Cannot imagine why.
> > 
> 
> We can't predict how slab will be extended in the future and this affects 
> anything created before g_cpucache_cpu <= EARLY.  This would introduce the 
> first problem with destroying such caches and is unnecessary if a 
> workaround exists.

These problems seem to indicate that the slab behaviour: expecting the
string to exist for the lifetime of the cache so there's no need to copy
it might be better.

This must be the behaviour all users of kmem_cache_create() expect
anyway, since all enterprise distributions use slab and they're not
getting bugs reported in this area.

So, why not simply patch slab to rely on the string lifetime being the
cache lifetime (or beyond) and therefore not having it take a copy?

James


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