Re: [PATCH] slab+slob: dup name string

[Glauber Costa]

On 05/22/2012 07:22 AM, David Rientjes wrote:
> On Mon, 21 May 2012, Glauber Costa wrote:
>
> > diff --git a/mm/slab.c b/mm/slab.c
> > index e901a36..cabd217 100644
> > --- a/mm/slab.c
> > +++ b/mm/slab.c
> > @@ -2118,6 +2118,7 @@ static void __kmem_cache_destroy(struct kmem_cache *cachep)
> >   			kfree(l3);
> >   		}
> >   	}
> > +	kfree(cachep->name);
> >   	kmem_cache_free(&cache_cache, cachep);
> >   }
> >
> > @@ -2526,9 +2527,14 @@ kmem_cache_create (const char *name, size_t size, size_t align,
> >   		BUG_ON(ZERO_OR_NULL_PTR(cachep->slabp_cache));
> >   	}
> >   	cachep->ctor = ctor;
> > -	cachep->name = name;
> >
> > -	if (setup_cpu_cache(cachep, gfp)) {
> > +	/* Can't do strdup while kmalloc is not up */
> > +	if (g_cpucache_up>  EARLY)
> > +		cachep->name = kstrdup(name, GFP_KERNEL);
> > +	else
> > +		cachep->name = name;
> > +
> > +	if (!cachep->name || setup_cpu_cache(cachep, gfp)) {
> >   		__kmem_cache_destroy(cachep);
> >   		cachep = NULL;
> >   		goto oops;
>
> This doesn't work if you kmem_cache_destroy() a cache that was created
> when g_cpucache_cpu<= EARLY, the kfree() will explode.  That never
> happens for any existing cache created in kmem_cache_init(), but this
> would introduce the first roadblock in doing so.  So you'll need some
> magic to determine whether the cache was allocated statically and suppress
> the kfree() in such a case.

Suggestions on how to do it other than using a flag?

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