mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
authorOscar Salvador <osalvador@suse.de>
Wed, 5 May 2021 01:39:48 +0000 (18:39 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 5 May 2021 18:27:27 +0000 (11:27 -0700)
commite3a9d9fcc3315993de2e9fcd7ea82fab84433815
tree0ae5712c9f1a5b34f8f485bf05887e983b652d1c
parent4a3e5de9c4ec41bb0684b0d4e0c16abc39617d88
mm,memory_hotplug: add kernel boot option to enable memmap_on_memory

Self stored memmap leads to a sparse memory situation which is
unsuitable for workloads that requires large contiguous memory chunks,
so make this an opt-in which needs to be explicitly enabled.

To control this, let memory_hotplug have its own memory space, as
suggested by David, so we can add memory_hotplug.memmap_on_memory
parameter.

Link: https://lkml.kernel.org/r/20210421102701.25051-7-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/admin-guide/kernel-parameters.txt
mm/Makefile
mm/memory_hotplug.c