[PATCH] memory hotplug: sysfs and add/remove functions

This adds generic memory add/remove and supporting functions for memory
hotplug into a new file as well as a memory hotplug kernel config option.

Individual architecture patches will follow.

For now, disable memory hotplug when swsusp is enabled.  There's a lot of
churn there right now.  We'll fix it up properly once it calms down.

Signed-off-by: Matt Tolentino <matthew.e.tolentino@intel.com>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/Kconfig b/mm/Kconfig
index f35a550..1a4473fc 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -112,6 +112,14 @@
 	def_bool y
 	depends on SPARSEMEM && !SPARSEMEM_STATIC
 
+# eventually, we can have this option just 'select SPARSEMEM'
+config MEMORY_HOTPLUG
+	bool "Allow for memory hot-add"
+	depends on SPARSEMEM && HOTPLUG && !SOFTWARE_SUSPEND
+
+comment "Memory hotplug is currently incompatible with Software Suspend"
+	depends on SPARSEMEM && HOTPLUG && SOFTWARE_SUSPEND
+
 # Heavily threaded applications may benefit from splitting the mm-wide
 # page_table_lock, so that faults on different parts of the user address
 # space can be handled with less contention: split it at this NR_CPUS.