Documentation: filesystems: proc: update meminfo section

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2075394

Documentation exposed to users via the kernel-doc package is outdated for /proc/meminfo. Let's pull in a recent upstream change that revises /proc/meminfo documentation.

commit 39799b6409febf628337bd7804c3861a9f7f7e8a Author: Johannes Weiner hannes@cmpxchg.org Date: Thu May 19 14:08:52 2022 -0700

Documentation: filesystems: proc: update meminfo section

Patch series "zswap: accounting & cgroup control", v2.

Zswap can consume nearly a quarter of RAM in the default configuration,
yet it's neither listed in /proc/meminfo, nor is it accounted and
manageable on a per-cgroup basis.

This makes reasoning about the memory situation on a host in general
rather difficult.  On shared/cgrouped hosts, the consequences are worse.
First, workloads can escape memory containment and cause resource priority
inversions: a lo-pri group can fill the global zswap pool and force a
hi-pri group out to disk.  Second, not all workloads benefit from zswap
equally.  Some even suffer when memory contents compress poorly, and are
better off going to disk swap directly.  On a host with mixed workloads,
it's currently not possible to enable zswap for one workload but not for
the other.

This series implements the missing global accounting as well as cgroup
tracking & control for zswap backing memory:

- Patch 1 refreshes the very out-of-date meminfo documentation in
  Documentation/filesystems/proc.rst.

- Patches 2-4 clean up related and adjacent options in Kconfig. Not
  actual dependencies, just things I noticed during development.

- Patch 5 adds meminfo and vmstat coverage for zswap consumption and
  activity.

- Patch 6 implements per-cgroup tracking & control of zswap memory.

This patch (of 6):

Add new entries.  Minor corrections and cleanups.

[hannes@cmpxchg.org: fix htmldocs warnings]
  Link: https://lkml.kernel.org/r/Ynve8dg4zJyhH2gW@cmpxchg.org
[hannes@cmpxchg.org: change `Unevictable' wording, per David]
  Link: https://lkml.kernel.org/r/YnwFraZlVWQoCjz3@cmpxchg.org
Link: https://lkml.kernel.org/r/20220510152847.230957-1-hannes@cmpxchg.org
Link: https://lkml.kernel.org/r/20220510152847.230957-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: David Hildenbrand david@redhat.com