How to destroy slab cache?

The kmem_cache_destroy function must be invoked to destroy a complete cache in which there are only unused objects. This function is needed primarily when removing modules that want to return all memory space allocated to them.

/**
 * kmem_cache_destroy - delete a cache
 * @cachep: the cache to destroy
 *
 * Remove a &struct kmem_cache object from the slab cache.
 *
 * It is expected this function will be called by a module when it is
 * unloaded. This will remove the cache completely, and avoid a duplicate
 * cache being allocated each time a module is loaded and unloaded, if the
 * module doesn't have persistent in-kernel storage across loads and unloads.
 *
 * The cache must be empty before calling this function.
 *
 * The caller must guarantee that noone will allocate memory from the cache
 * during the kmem_cache_destroy().
 */
void kmem_cache_destroy(struct kmem_cache *cachep)
{
    BUG_ON(!cachep || in_interrupt());

    /* Find the cache in the chain of caches. */
    get_online_cpus();
    mutex_lock(&cache_chain_mutex);
    /*
     * the chain is never empty, cache_cache is never destroyed
     */
    list_del(&cachep->next);
    if (__cache_shrink(cachep)) {
        slab_error(cachep, "Can't free all objects");
        list_add(&cachep->next, &cache_chain);
        mutex_unlock(&cache_chain_mutex);
        put_online_cpus();
        return;
    }

    if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
        rcu_barrier();

    __kmem_cache_destroy(cachep);
    mutex_unlock(&cache_chain_mutex);
    put_online_cpus();
}
EXPORT_SYMBOL(kmem_cache_destroy);