On Tue, 28 Aug 2012 18:00:11 +0800
wency@cn.fujitsu.com wrote:

+int remove_memory(int nid, u64 start, u64 size)
+{
+	int ret = -EBUSY;
+	lock_memory_hotplug();
+	/*
+	 * The memory might become online by other task, even if you offine it.
+	 * So we check whether the cpu has been onlined or not.

I think you meant "memory", not "cpu".

Actually, "check whether any part of this memory range has been
onlined" would be better.  If that is accurate ;)

+	 */
+	if (!is_memblk_offline(start, size)) {
+		pr_warn("memory removing [mem %#010llx-%#010llx] failed, "
+			"because the memmory range is online\n",
+			start, start + size);
+		ret = -EAGAIN;
+	}
+
+	unlock_memory_hotplug();
+	return ret;
+
+}
+EXPORT_SYMBOL_GPL(remove_memory);