mm/slub: introduce __kmem_cache_free_bulk() without free hooks

mm/slub: introduce __kmem_cache_free_bulk() without free hooks

Currently, when __kmem_cache_alloc_bulk() fails, it frees back the
objects that were allocated before the failure, using
kmem_cache_free_bulk(). Because kmem_cache_free_bulk() calls the free
hooks (kasan etc.) and those expect objects processed by the post alloc
hooks, slab_post_alloc_hook() is called before kmem_cache_free_bulk().

This is wasteful, although not a big concern in practice for the very
rare error path. But in order to efficiently handle percpu array batch
refill and free in the following patch, we will also need a variant of
kmem_cache_free_bulk() that avoids the free hooks. So introduce it first
and use it in the error path too.

As a consequence, __kmem_cache_alloc_bulk() no longer needs the objcg
parameter, remove it.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>