mm, memory_hotplug: move movable_node to the hotplug proper

movable_node_is_enabled is defined in memblock proper while it is
initialized from the memory hotplug proper.  This is quite messy and it
makes a dependency between the two so move movable_node along with the
helper functions to memory_hotplug.

To make it more entertaining the kernel parameter is ignored unless
CONFIG_HAVE_MEMBLOCK_NODE_MAP=y because we do not have the node
information for each memblock otherwise.  So let's warn when the option
is disabled.

Link: http://lkml.kernel.org/r/20170529114141.536-4-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>

include/linux/memblock.h

@@ -57,8 +57,6 @@ struct memblock {
 
 extern struct memblock memblock;
 extern int memblock_debug;
-/* If movable_node boot option specified */
-extern bool movable_node_enabled;
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
@@ -172,11 +170,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
 	return m->flags & MEMBLOCK_HOTPLUG;
 }
 
-static inline bool __init_memblock movable_node_is_enabled(void)
-{
-	return movable_node_enabled;
-}
-
 static inline bool memblock_is_mirror(struct memblock_region *m)
 {
 	return m->flags & MEMBLOCK_MIRROR;

include/linux/memory_hotplug.h

@@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
 extern int try_online_node(int nid);
 
 extern bool memhp_auto_online;
+/* If movable_node boot option specified */
+extern bool movable_node_enabled;
+static inline bool movable_node_is_enabled(void)
+{
+	return movable_node_enabled;
+}
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern bool is_pageblock_removable_nolock(struct page *page);
@@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
 static inline void mem_hotplug_begin(void) {}
 static inline void mem_hotplug_done(void) {}
 
+static inline bool movable_node_is_enabled(void)
+{
+	return false;
+}
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
 #ifdef CONFIG_MEMORY_HOTREMOVE

mm/memblock.c

@@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-bool movable_node_enabled __initdata_memblock = false;
 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;

mm/memory_hotplug.c

@@ -79,6 +79,8 @@ static struct {
 #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
 #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
 
+bool movable_node_enabled = false;
+
 #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
 bool memhp_auto_online;
 #else
@@ -1572,7 +1574,11 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 
 static int __init cmdline_parse_movable_node(char *p)
 {
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
 	movable_node_enabled = true;
+#else
+	pr_warn("movable_node parameter depends on CONFIG_HAVE_MEMBLOCK_NODE_MAP to work properly\n");
+#endif
 	return 0;
 }
 early_param("movable_node", cmdline_parse_movable_node);