mm,doc: Add new documentation structure

Closely following the outline of Mel Gorman's book "Understanding the
Linux Virtual Memory Manager", add a new outline.  Preserve the current
contents of the mm underneath the new outline so we can transition those
documents to a more sensible place later.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20220507134947.444287-1-willy@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/vm/bootmem.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===========
+Boot Memory
+===========

Documentation/vm/index.rst

@@ -2,12 +2,39 @@
 Linux Memory Management Documentation
 =====================================
 
-This is a collection of documents about the Linux memory management (mm)
-subsystem internals with different level of details ranging from notes and
-mailing list responses for elaborating descriptions of data structures and
-algorithms.  If you are looking for advice on simply allocating memory, see the
-:ref:`memory_allocation`.  For controlling and tuning guides, see the
-:doc:`admin guide <../admin-guide/mm/index>`.
+Memory Management Guide
+=======================
+
+This is a guide to understanding the memory management subsystem
+of Linux.  If you are looking for advice on simply allocating memory,
+see the :ref:`memory_allocation`.  For controlling and tuning guides,
+see the :doc:`admin guide <../admin-guide/mm/index>`.
+
+.. toctree::
+   :maxdepth: 1
+
+   physical_memory
+   page_tables
+   process_addrs
+   bootmem
+   page_allocation
+   vmalloc
+   slab
+   highmem
+   page_reclaim
+   swap
+   page_cache
+   shmfs
+   oom
+
+Legacy Documentation
+====================
+
+This is a collection of older documents about the Linux memory management
+(MM) subsystem internals with different level of details ranging from
+notes and mailing list responses for elaborating descriptions of data
+structures and algorithms.  It should all be integrated nicely into the
+above structured documentation, or deleted if it has served its purpose.
 
 .. toctree::
    :maxdepth: 1
@@ -18,7 +45,6 @@ algorithms.  If you are looking for advice on simply allocating memory, see the
    damon/index
    free_page_reporting
    frontswap
-   highmem
    hmm
    hwpoison
    hugetlbfs_reserv

Documentation/vm/oom.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+Out Of Memory Handling
+======================

Documentation/vm/page_allocation.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Page Allocation
+===============

Documentation/vm/page_cache.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+==========
+Page Cache
+==========

Documentation/vm/page_reclaim.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+============
+Page Reclaim
+============

Documentation/vm/page_tables.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===========
+Page Tables
+===========

Documentation/vm/physical_memory.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Physical Memory
+===============

Documentation/vm/process_addrs.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+Process Addresses
+=================

Documentation/vm/shmfs.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+========================
+Shared Memory Filesystem
+========================

Documentation/vm/slab.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Slab Allocation
+===============

Documentation/vm/swap.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+====
+Swap
+====

Documentation/vm/vmalloc.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+======================================
+Virtually Contiguous Memory Allocation
+======================================