From 77f9a542c8b62499643cc56ca1c6a3df3d47c994 Mon Sep 17 00:00:00 2001
From: Wen Congyang <wency@cn.fujitsu.com>
Date: Wed, 20 Feb 2013 13:14:22 +1100
Subject: [PATCH] memory-hotplug: export the function try_offline_node()

try_offline_node() will be needed in the tristate
drivers/acpi/processor_driver.c.

The node will be offlined when all memory/cpu on the node have been
hotremoved.  So we need the function try_offline_node() in cpu-hotplug
path.

If the memory-hotplug is disabled, and cpu-hotplug is enabled
1. no memory no the node
   we don't online the node, and cpu's node is the nearest node.
2. the node contains some memory
   the node has been onlined, and cpu's node is still needed
   to migrate the sleep task on the cpu to the same node.

So we do nothing in try_offline_node() in this case.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/memory_hotplug.h | 2 ++
 mm/memory_hotplug.c            | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 69903ccf549e..0b2878e34d1e 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -193,6 +193,7 @@ extern void get_page_bootmem(unsigned long ingo, struct page *page,
 
 void lock_memory_hotplug(void);
 void unlock_memory_hotplug(void);
+extern void try_offline_node(int nid);
 
 #else /* ! CONFIG_MEMORY_HOTPLUG */
 /*
@@ -227,6 +228,7 @@ static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
 
 static inline void lock_memory_hotplug(void) {}
 static inline void unlock_memory_hotplug(void) {}
+static inline void try_offline_node(int nid) {}
 
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 559e4409cf90..d4a9820edfc7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1706,7 +1706,7 @@ static int check_cpu_on_node(void *data)
 }
 
 /* offline the node if all memory sections of this node are removed */
-static void try_offline_node(int nid)
+void try_offline_node(int nid)
 {
 	pg_data_t *pgdat = NODE_DATA(nid);
 	unsigned long start_pfn = pgdat->node_start_pfn;
@@ -1762,6 +1762,7 @@ static void try_offline_node(int nid)
 	 */
 	memset(pgdat, 0, sizeof(*pgdat));
 }
+EXPORT_SYMBOL(try_offline_node);
 
 int __ref remove_memory(int nid, u64 start, u64 size)
 {
-- 
2.39.5