2012/8/4 Christoph Lameter <cl@xxxxxxxxx>:
> Duping of the slabname has to be done by each slab. Moving this code
> to slab_common avoids duplicate implementations.
>
> With this patch we have common string handling for all slab allocators.
> Strings passed to kmem_cache_create() are copied internally. Subsystems
> can create temporary strings to create slab caches.
>
> Slabs allocated in early states of bootstrap will never be freed (and those
> can never be freed since they are essential to slab allocator operations).
> During bootstrap we therefore do not have to worry about duping names.
>
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
We can remove some comment for name param of __kmem_cache_create() in slab.c.
> Index: linux-2.6/mm/slab_common.c
> ===================================================================
> --- linux-2.6.orig/mm/slab_common.c 2012-08-03 09:02:50.000000000 -0500
> +++ linux-2.6/mm/slab_common.c 2012-08-03 09:02:54.900587462 -0500
> @@ -54,6 +54,7 @@ struct kmem_cache *kmem_cache_create(con
> {
> struct kmem_cache *s;
> int err = 0;
> + char *n;
>
> #ifdef CONFIG_DEBUG_VM
> if (!name || in_interrupt() || size < sizeof(void *) ||
> @@ -93,16 +94,26 @@ struct kmem_cache *kmem_cache_create(con
> WARN_ON(strchr(name, ' ')); /* It confuses parsers */
> #endif
>
> - s = __kmem_cache_create(name, size, align, flags, ctor);
> - if (!s)
> - err = -ENOSYS; /* Until __kmem_cache_create returns code */
> + n = kstrdup(name, GFP_KERNEL);
> + if (!n) {
> + err = -ENOMEM;
> + goto out_locked;
> + }
> +
> + s = __kmem_cache_create(n, size, align, flags, ctor);
We need to remove CONFIG_DEBUG_VM for out_locked now,
although later patch handles it.
> - /*
> - * Check if the slab has actually been created and if it was a
> - * real instatiation. Aliases do not belong on the list
> - */
> - if (s && s->refcount == 1)
> - list_add(&s->list, &slab_caches);
> + if (s) {
> + /*
> + * Check if the slab has actually been created and if it was a
> + * real instatiation. Aliases do not belong on the list
> + */
> + if (s->refcount == 1)
> + list_add(&s->list, &slab_caches);
> +
> + } else {
> + kfree(n);
> + err = -ENOSYS; /* Until __kmem_cache_create returns code */
> + }
In mergeable case, leak for name is possible.
__kmem_cache_create() doesn't set name to s->name in mergeable case.
So, this memory can't be freed.
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