thp: change_huge_pmd(): make sure we don't try to make a page writable

[firefly-linux-kernel-4.4.55.git] / mm / nommu.c

diff --git a/mm/nommu.c b/mm/nommu.c
index 45131b41bcdbaf4fdfd6c411a6d0aef526ed0883..79c3cac87afa1d1f96fc9397f50bb370980e0a84 100644 (file)
--- 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);