vmw_balloon: Compaction support

Add support for compaction for VMware balloon. Since unlike the virtio
balloon, we also support huge-pages, which are not going through
compaction, we keep these pages in vmballoon and handle this list
separately. We use the same lock to protect both lists, as this lock is
not supposed to be contended.

Doing so also eliminates the need for the page_size lists. We update the
accounting as needed to reflect inflation, deflation and migration to be
reflected in vmstat.

Since VMware balloon now provides statistics for inflation, deflation
and migration in vmstat, select MEMORY_BALLOON in Kconfig.

Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/Kconfig

@@ -386,6 +386,7 @@ config SPEAR13XX_PCIE_GADGET
 config VMWARE_BALLOON
 	tristate "VMware Balloon Driver"
 	depends on VMWARE_VMCI && X86 && HYPERVISOR_GUEST
+	select MEMORY_BALLOON
 	help
 	  This is VMware physical memory management driver which acts
 	  like a "balloon" that can be inflated to reclaim physical pages