mm/memcontrol: add per-memcg pgpgin/pswpin counter

mm/memcontrol: add per-memcg pgpgin/pswpin counter

In proactive memory reclamation scenarios, it is necessary to estimate the
pswpin and pswpout metrics of the cgroup to determine whether to continue
reclaiming anonymous pages in the current batch.  This patch will collect
these metrics and expose them.

Link: https://lkml.kernel.org/r/20240830082244.156923-1-jingxiangzeng.cas@gmail.com
Signed-off-by: Jingxiang Zeng <linuszeng@tencent.com>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>