memcg: only check memcg_kmem_skip_account in __memcg_kmem_get_cache

	*_memcg = NULL;

	*_memcg = NULL;

	/*

	 * Disabling accounting is only relevant for some specific memcg

	 * internal allocations. Therefore we would initially not have such

	 * check here, since direct calls to the page allocator that are

	 * accounted to kmemcg (alloc_kmem_pages and friends) only happen

	 * outside memcg core. We are mostly concerned with cache allocations,

	 * and by having this test at memcg_kmem_get_cache, we are already able

	 * to relay the allocation to the root cache and bypass the memcg cache

	 * altogether.

	 *

	 * There is one exception, though: the SLUB allocator does not create

	 * large order caches, but rather service large kmallocs directly from

	 * the page allocator. Therefore, the following sequence when backed by

	 * the SLUB allocator:

	 *

	 *	memcg_stop_kmem_account();

	 *	kmalloc(<large_number>)

	 *	memcg_resume_kmem_account();

	 *

	 * would effectively ignore the fact that we should skip accounting,

	 * since it will drive us directly to this function without passing

	 * through the cache selector memcg_kmem_get_cache. Such large

	 * allocations are extremely rare but can happen, for instance, for the

	 * cache arrays. We bring this test here.

	 */

	if (current->memcg_kmem_skip_account)

		return true;

	memcg = get_mem_cgroup_from_mm(current->mm);

	memcg = get_mem_cgroup_from_mm(current->mm);

	if (!memcg_kmem_is_active(memcg)) {

	if (!memcg_kmem_is_active(memcg)) {