mm: memblock: enforce overlap of memory.memblock and memory.reserved

mm: memblock: enforce overlap of memory.memblock and memory.reserved

Patch series "mm: fix initialization of struct page for holes in  memory layout", v2.

Commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions
rather that check each PFN") exposed several issues with the memory map
initialization and these patches fix those issues.

Initially there were crashes during compaction that Qian Cai reported back
in April [1].  It seemed back then that the probelm was fixed, but a few
weeks ago Andrea Arcangeli hit the same bug [2] and after a long
discussion between us [3] I think these patches are the proper fix.

[1] https://lore.kernel.org/lkml/8C537EB7-85EE-4DCF-943E-3CC0ED0DF56D@lca.pw
[2] https://lore.kernel.org/lkml/20201121194506.13464-1-aarcange@redhat.com
[3] https://lore.kernel.org/mm-commits/20201206005401.qKuAVgOXr%akpm@linux-foundation.org

This patch (of 2):

memblock does not require that the reserved memory ranges will be a subset
of memblock.memory.

As a result there may be reserved pages that are not in the range of any
zone or node because zone and node boundaries are detected based on
memblock.memory and pages that only present in memblock.reserved are not
taken into account during zone/node size detection.

Make sure that all ranges in memblock.reserved are added to
memblock.memory before calculating node and zone boundaries.

Link: https://lkml.kernel.org/r/20201209214304.6812-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20201209214304.6812-2-rppt@kernel.org
Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>