mm: allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove
CONFIG_MIGRATION currently depends on CONFIG_NUMA or on the architecture
being able to hot-remove memory. The main users of page migration such as
sys_move_pages(), sys_migrate_pages() and cpuset process migration are
only beneficial on NUMA so it makes sense.
As memory compaction will operate within a zone and is useful on both NUMA
and non-NUMA systems, this patch allows CONFIG_MIGRATION to be set if the
user selects CONFIG_COMPACTION as an option.
[akpm@linux-foundation.org: Depend on CONFIG_HUGETLB_PAGE]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/Kconfig b/mm/Kconfig
index 9c61158..527136b 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -172,6 +172,15 @@
default "4"
#
+# support for memory compaction
+config COMPACTION
+ bool "Allow for memory compaction"
+ select MIGRATION
+ depends on EXPERIMENTAL && HUGETLB_PAGE && MMU
+ help
+ Allows the compaction of memory for the allocation of huge pages.
+
+#
# support for page migration
#
config MIGRATION
@@ -180,9 +189,11 @@
depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE
help
Allows the migration of the physical location of pages of processes
- while the virtual addresses are not changed. This is useful for
- example on NUMA systems to put pages nearer to the processors accessing
- the page.
+ while the virtual addresses are not changed. This is useful in
+ two situations. The first is on NUMA systems to put pages nearer
+ to the processors accessing. The second is when allocating huge
+ pages as migration can relocate pages to satisfy a huge page
+ allocation instead of reclaiming.
config PHYS_ADDR_T_64BIT
def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT