mm, swap: support flexible batch freeing of slots in different memcgs

mm, swap: support flexible batch freeing of slots in different memcgs

Instead of requiring the caller to ensure all slots are in the same memcg,
make the function handle different memcgs at once.

This is both a micro optimization and required for removing the memcg
lookup in the page table layer, so it can be unified at the swap layer.

We are not removing the memcg lookup in the page table in this commit.  It
has to be done after the memcg lookup is deferred to the swap layer.

Link: https://lore.kernel.org/20260517-swap-table-p4-v5-7-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>