From 468c17180d01b83f5b2758152347f25bbd6d84d4 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@microsoft.com>
Date: Thu, 15 Nov 2012 14:34:42 -0800
Subject: [PATCH] --- yaml --- r: 336969 b: refs/heads/master c:
 997071bcb34005f42e0fe5bc7930e895b070f251 h: refs/heads/master i:   336967:
 fd0ee5b9a59255bde003830f8124cc3a59536735 v: v3

---
 [refs]                              |  2 +-
 trunk/drivers/xen/xen-selfballoon.c |  2 +-
 trunk/include/linux/mman.h          |  2 ++
 trunk/mm/mmap.c                     | 14 ++++++++++++++
 trunk/mm/nommu.c                    | 15 +++++++++++++++
 5 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index f62c0a0faf32..ed560aa256b3 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d892de8d3fb1e807de561289cfb1fed42950440a
+refs/heads/master: 997071bcb34005f42e0fe5bc7930e895b070f251
diff --git a/trunk/drivers/xen/xen-selfballoon.c b/trunk/drivers/xen/xen-selfballoon.c
index 7d041cb6da26..2552d3e0a70f 100644
--- a/trunk/drivers/xen/xen-selfballoon.c
+++ b/trunk/drivers/xen/xen-selfballoon.c
@@ -222,7 +222,7 @@ static void selfballoon_process(struct work_struct *work)
 	if (xen_selfballooning_enabled) {
 		cur_pages = totalram_pages;
 		tgt_pages = cur_pages; /* default is no change */
-		goal_pages = percpu_counter_read_positive(&vm_committed_as) +
+		goal_pages = vm_memory_committed() +
 				totalreserve_pages +
 				MB2PAGES(selfballoon_reserved_mb);
 #ifdef CONFIG_FRONTSWAP
diff --git a/trunk/include/linux/mman.h b/trunk/include/linux/mman.h
index d09dde1e57fb..9aa863da287f 100644
--- a/trunk/include/linux/mman.h
+++ b/trunk/include/linux/mman.h
@@ -11,6 +11,8 @@ extern int sysctl_overcommit_memory;
 extern int sysctl_overcommit_ratio;
 extern struct percpu_counter vm_committed_as;
 
+unsigned long vm_memory_committed(void);
+
 static inline void vm_acct_memory(long pages)
 {
 	percpu_counter_add(&vm_committed_as, pages);
diff --git a/trunk/mm/mmap.c b/trunk/mm/mmap.c
index 2d942353d681..b064822be82e 100644
--- a/trunk/mm/mmap.c
+++ b/trunk/mm/mmap.c
@@ -88,6 +88,20 @@ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
  */
 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
 
+/*
+ * The global memory commitment made in the system can be a metric
+ * that can be used to drive ballooning decisions when Linux is hosted
+ * as a guest. On Hyper-V, the host implements a policy engine for dynamically
+ * balancing memory across competing virtual machines that are hosted.
+ * Several metrics drive this policy engine including the guest reported
+ * memory commitment.
+ */
+unsigned long vm_memory_committed(void)
+{
+	return percpu_counter_read_positive(&vm_committed_as);
+}
+EXPORT_SYMBOL_GPL(vm_memory_committed);
+
 /*
  * Check that a process has enough memory to allocate a new virtual
  * mapping. 0 means there is enough memory for the allocation to
diff --git a/trunk/mm/nommu.c b/trunk/mm/nommu.c
index 45131b41bcdb..79c3cac87afa 100644
--- a/trunk/mm/nommu.c
+++ b/trunk/mm/nommu.c
@@ -66,6 +66,21 @@ int heap_stack_gap = 0;
 
 atomic_long_t mmap_pages_allocated;
 
+/*
+ * The global memory commitment made in the system can be a metric
+ * that can be used to drive ballooning decisions when Linux is hosted
+ * as a guest. On Hyper-V, the host implements a policy engine for dynamically
+ * balancing memory across competing virtual machines that are hosted.
+ * Several metrics drive this policy engine including the guest reported
+ * memory commitment.
+ */
+unsigned long vm_memory_committed(void)
+{
+	return percpu_counter_read_positive(&vm_committed_as);
+}
+
+EXPORT_SYMBOL_GPL(vm_memory_committed);
+
 EXPORT_SYMBOL(mem_map);
 EXPORT_SYMBOL(num_physpages);