linux-kernel - Re: [PATCH v2] slab+slob: dup name string

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Message-ID: <alpine.DEB.2.00.1205231759460.28167@chino.kir.corp.google.com>
Date:	Wed, 23 May 2012 18:01:51 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Christoph Lameter <cl@...ux.com>
cc:	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 v2] slab+slob: dup name string

On Wed, 23 May 2012, Christoph Lameter wrote:

> > No, it's not, there's no reason to prevent caches created before
> > g_cpucache_up <= EARLY to be destroyed because it makes a patch easier to
> > implement and then leave that little gotcha as an undocumented treasure
> > for someone to find when they try it later on.
> 
> g_cpucache_up <= EARLY is slab bootstrap code and the system is in a
> pretty fragile state. Plus the the kmalloc logic *depends* on these
> caches being present. Removing those is not a good idea. The other caches
> that are created at that point are needed to create more caches.
> 
> There is no reason to remove these caches.
> 

Yes, we know that we don't want to remove the caches that are currently 
created in kmem_cache_init(), it would be a pretty stupid thing to do.  
I'm talking about the possibility of creating additional caches while 
g_cpucache_up <= EARLY in the future and then finding that you can't 
destroy them because of this string allocation.  I don't think it's too 
difficult to statically allocate space for these names and then test for 
it before doing kfree() in kmem_cache_destroy(), it's not performance 
critical.
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