mm/balloon_compaction: add vmstat counters and kpageflags bit

Always mark pages with PageBalloon even if balloon compaction is disabled
and expose this mark in /proc/kpageflags as KPF_BALLOON.

Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
"balloon_deflate" and "balloon_migrate".  They accumulate balloon
activity.  Current size of balloon is (balloon_inflate - balloon_deflate)
pages.

All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
It should be selected by ballooning driver which wants use this feature.
Currently virtio-balloon is the only user.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index 0ceb8a567dab..1d1ae6b078fd 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -231,11 +231,16 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
         boolean
 
 #
+# support for memory balloon
+config MEMORY_BALLOON
+        boolean
+
+#
 # support for memory balloon compaction
 config BALLOON_COMPACTION
         bool "Allow for balloon memory compaction/migration"
         def_bool y
-        depends on COMPACTION && VIRTIO_BALLOON
+        depends on COMPACTION && MEMORY_BALLOON
         help
           Memory fragmentation introduced by ballooning might reduce
           significantly the number of 2MB contiguous memory blocks that can be