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

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Date:	Wed, 23 May 2012 08:53:29 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	David Rientjes <rientjes@...gle.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 Tue, 22 May 2012, David Rientjes wrote:

> On Tue, 22 May 2012, Christoph Lameter wrote:
>
> > > [ v2: Also dup string for early caches, requested by David Rientjes ]
> >
> > kstrdups that early could cause additional issues. Its better to leave
> > things as they were.
> >
>
> 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.

> This is much easier to do, just statically allocate the const char *'s
> needed for the boot caches and then set their ->name's manually in
> kmem_cache_init() and then avoid the kfree() in kmem_cache_destroy() if
> the name is between &boot_cache_name[0] and &boot_cache_name[n].

Yeah that is already occurring for some of the boot caches.

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