2 files changed, 29 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 9a796c4..7d41605 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -89,6 +89,20 @@ 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
  * succeed and -ENOMEM implies there is not.
diff --git a/mm/nommu.c b/mm/nommu.c
index 45131b4..79c3cac 100644
--- a/mm/nommu.c
+++ b/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);