mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

Commit 20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for
movable-dedicated node") has introduced CONFIG_MOVABLE_NODE without a
good explanation on why it is actually useful.

It makes a lot of sense to make movable node semantic opt in but we
already have that because the feature has to be explicitly enabled on
the kernel command line.  A config option on top only makes the
configuration space larger without a good reason.  It also adds an
additional ifdefery that pollutes the code.

Just drop the config option and make it de-facto always enabled.  This
shouldn't introduce any change to the semantic.

Link: http://lkml.kernel.org/r/20170529114141.536-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Kani Toshimitsu <toshi.kani@hpe.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 0 insertions, 34 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index 9870baa..857f6ef 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -149,32 +149,6 @@ config NO_BOOTMEM
 config MEMORY_ISOLATION
 	bool
 
-config MOVABLE_NODE
-	bool "Enable to assign a node which has only movable memory"
-	depends on HAVE_MEMBLOCK
-	depends on NO_BOOTMEM
-	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
-	depends on NUMA
-	default n
-	help
-	  Allow a node to have only movable memory.  Pages used by the kernel,
-	  such as direct mapping pages cannot be migrated.  So the corresponding
-	  memory device cannot be hotplugged.  This option allows the following
-	  two things:
-	  - When the system is booting, node full of hotpluggable memory can
-	  be arranged to have only movable memory so that the whole node can
-	  be hot-removed. (need movable_node boot option specified).
-	  - After the system is up, the option allows users to online all the
-	  memory of a node as movable memory so that the whole node can be
-	  hot-removed.
-
-	  Users who don't use the memory hotplug feature are fine with this
-	  option on since they don't specify movable_node boot option or they
-	  don't online memory as movable.
-
-	  Say Y here if you want to hotplug a whole node.
-	  Say N here if you want kernel to use memory on all nodes evenly.
-
 #
 # Only be set on architectures that have completely implemented memory hotplug
 # feature. If you are not sure, don't touch it.
diff --git a/mm/memblock.c b/mm/memblock.c
index 7b8a5db..41eaeeb 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,9 +54,7 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-#ifdef CONFIG_MOVABLE_NODE
 bool movable_node_enabled __initdata_memblock = false;
-#endif
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9373198..0dc8cf0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1572,11 +1572,7 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 
 static int __init cmdline_parse_movable_node(char *p)
 {
-#ifdef CONFIG_MOVABLE_NODE
 	movable_node_enabled = true;
-#else
-	pr_warn("movable_node option not supported\n");
-#endif
 	return 0;
 }
 early_param("movable_node", cmdline_parse_movable_node);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a35add8..bd65b60 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -113,9 +113,7 @@ nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
 #ifdef CONFIG_HIGHMEM
 	[N_HIGH_MEMORY] = { { [0] = 1UL } },
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	[N_MEMORY] = { { [0] = 1UL } },
-#endif
 	[N_CPU] = { { [0] = 1UL } },
 #endif	/* NUMA */
 };