From 03ad702c1be3466b982099ec8764a045411cf3bf Mon Sep 17 00:00:00 2001
From: davidjumani <dj.davidjumani1994@gmail.com>
Date: Tue, 30 Mar 2021 14:05:46 +0530
Subject: [PATCH] server: Set free memory to zero if greater than total memory
 (#4571)

Fixes https://github.com/apache/cloudstack/issues/4566

Sets `memoryintfreekbs` to zero if it is greater than `memorykbs`. Caused by KVM returning the RSS memory of the process running the VM rather than the free memory inside the VM.

Co-authored-by: dahn <daan.hoogland@gmail.com>
---
 .../org/apache/cloudstack/api/response/UserVmResponse.java | 2 +-
 .../java/com/cloud/api/query/dao/UserVmJoinDaoImpl.java    | 7 +++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/api/src/main/java/org/apache/cloudstack/api/response/UserVmResponse.java b/api/src/main/java/org/apache/cloudstack/api/response/UserVmResponse.java
index 44eaba7f313..ea5300e7875 100644
--- a/api/src/main/java/org/apache/cloudstack/api/response/UserVmResponse.java
+++ b/api/src/main/java/org/apache/cloudstack/api/response/UserVmResponse.java
@@ -209,7 +209,7 @@ public class UserVmResponse extends BaseResponseWithTagInformation implements Co
     private Long memoryKBs;
 
     @SerializedName("memoryintfreekbs")
-    @Param(description = "the internal memory thats free in vm")
+    @Param(description = "the internal memory that's free in vm or zero if it can not be calculated")
     private Long memoryIntFreeKBs;
 
     @SerializedName("memorytargetkbs")
diff --git a/server/src/main/java/com/cloud/api/query/dao/UserVmJoinDaoImpl.java b/server/src/main/java/com/cloud/api/query/dao/UserVmJoinDaoImpl.java
index 8e489f89eca..1589f0151fe 100644
--- a/server/src/main/java/com/cloud/api/query/dao/UserVmJoinDaoImpl.java
+++ b/server/src/main/java/com/cloud/api/query/dao/UserVmJoinDaoImpl.java
@@ -222,8 +222,11 @@ public class UserVmJoinDaoImpl extends GenericDaoBaseWithTagInformation<UserVmJo
                 userVmResponse.setDiskKbsWrite((long)vmStats.getDiskWriteKBs());
                 userVmResponse.setDiskIORead((long)vmStats.getDiskReadIOs());
                 userVmResponse.setDiskIOWrite((long)vmStats.getDiskWriteIOs());
-                userVmResponse.setMemoryKBs((long)vmStats.getMemoryKBs());
-                userVmResponse.setMemoryIntFreeKBs((long)vmStats.getIntFreeMemoryKBs());
+                long totalMemory = (long)vmStats.getMemoryKBs();
+                long freeMemory = (long)vmStats.getIntFreeMemoryKBs();
+                long correctedFreeMemory = freeMemory >= totalMemory ? 0 : freeMemory;
+                userVmResponse.setMemoryKBs(totalMemory);
+                userVmResponse.setMemoryIntFreeKBs(correctedFreeMemory);
                 userVmResponse.setMemoryTargetKBs((long)vmStats.getTargetMemoryKBs());
 
             }