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>

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 69903ccf549e2b6f70b2074b4ced5ddb6cc8b944..0b2878e34d1ea75ca6388a9baba9d2f3ae38a0de 100644 (file)
--- 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 559e4409cf909071cd885867f4aeecd26cd48fbd..d4a9820edfc7a013f979e3a60aa8a5717c6f30b8 100644 (file)
--- 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)
 {