diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index 67fe1491c48be..6d3fabc3f93d4 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -1032,31 +1032,13 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
         // Sets the display content for the children.
         onDisplayChanged(this);
 
-        // Add itself as a child to the root container.
-        mWmService.mRoot.addChild(this, POSITION_BOTTOM);
-
-        // TODO(b/62541591): evaluate whether this is the best spot to declare the
-        // {@link DisplayContent} ready for use.
-        mDisplayReady = true;
-
-        mWmService.mAnimator.addDisplayLocked(mDisplayId);
-        mInputMonitor = new InputMonitor(mWmService, mDisplayId);
+        mInputMonitor = new InputMonitor(mWmService, this);
         mInsetsStateController = new InsetsStateController(this);
         mInsetsPolicy = new InsetsPolicy(mInsetsStateController, this);
 
-        if (DEBUG_DISPLAY) Slog.v(TAG_WM, "Adding display=" + display);
+        if (DEBUG_DISPLAY) Slog.v(TAG_WM, "Creating display=" + display);
 
         mWmService.mDisplayWindowSettings.applySettingsToDisplayLocked(this);
-
-        if (mWmService.mDisplayManagerInternal != null) {
-            mWmService.mDisplayManagerInternal
-                    .setDisplayInfoOverrideFromWindowManager(mDisplayId, getDisplayInfo());
-            configureDisplayPolicy();
-        }
-
-        reconfigureDisplayLocked();
-        onRequestedOverrideConfigurationChanged(getRequestedOverrideConfiguration());
-        mWmService.mDisplayNotificationController.dispatchDisplayAdded(this);
     }
 
     boolean isReady() {
@@ -4994,6 +4976,24 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
         // we create the root surfaces explicitly rather than chaining
         // up as the default implementation in onParentChanged does. So we
         // explicitly do NOT call super here.
+
+        if (!isReady()) {
+            // TODO(b/62541591): evaluate whether this is the best spot to declare the
+            // {@link DisplayContent} ready for use.
+            mDisplayReady = true;
+
+            mWmService.mAnimator.addDisplayLocked(mDisplayId);
+
+            if (mWmService.mDisplayManagerInternal != null) {
+                mWmService.mDisplayManagerInternal
+                        .setDisplayInfoOverrideFromWindowManager(mDisplayId, getDisplayInfo());
+                configureDisplayPolicy();
+            }
+
+            reconfigureDisplayLocked();
+            onRequestedOverrideConfigurationChanged(getRequestedOverrideConfiguration());
+            mWmService.mDisplayNotificationController.dispatchDisplayAdded(this);
+        }
     }
 
     @Override
diff --git a/services/core/java/com/android/server/wm/InputMonitor.java b/services/core/java/com/android/server/wm/InputMonitor.java
index a8ff5002bc584..c4b67d76607ee 100644
--- a/services/core/java/com/android/server/wm/InputMonitor.java
+++ b/services/core/java/com/android/server/wm/InputMonitor.java
@@ -151,10 +151,10 @@ final class InputMonitor {
 
     private final UpdateInputWindows mUpdateInputWindows = new UpdateInputWindows();
 
-    public InputMonitor(WindowManagerService service, int displayId) {
+    InputMonitor(WindowManagerService service, DisplayContent displayContent) {
         mService = service;
-        mDisplayContent = mService.mRoot.getDisplayContent(displayId);
-        mDisplayId = displayId;
+        mDisplayContent = displayContent;
+        mDisplayId = displayContent.getDisplayId();
         mInputTransaction = mService.mTransactionFactory.get();
         mHandler = mService.mAnimationHandler;
         mUpdateInputForAllWindowsConsumer = new UpdateInputForAllWindowsConsumer();
diff --git a/services/core/java/com/android/server/wm/RootWindowContainer.java b/services/core/java/com/android/server/wm/RootWindowContainer.java
index 704ab677f91d8..a7bf6600d7b56 100644
--- a/services/core/java/com/android/server/wm/RootWindowContainer.java
+++ b/services/core/java/com/android/server/wm/RootWindowContainer.java
@@ -1377,6 +1377,7 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
         for (int displayNdx = 0; displayNdx < displays.length; ++displayNdx) {
             final Display display = displays[displayNdx];
             final DisplayContent displayContent = new DisplayContent(display, this);
+            addChild(displayContent, POSITION_BOTTOM);
             if (displayContent.mDisplayId == DEFAULT_DISPLAY) {
                 mDefaultDisplay = displayContent;
             }
@@ -1445,6 +1446,7 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
         }
         // The display hasn't been added to ActivityManager yet, create a new record now.
         displayContent = new DisplayContent(display, this);
+        addChild(displayContent, POSITION_BOTTOM);
         return displayContent;
     }
 
diff --git a/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java b/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java
index 05d1c76fed8cc..e50750841e20f 100644
--- a/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java
+++ b/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java
@@ -408,6 +408,16 @@ public class SystemServicesTestRule implements TestRule {
         }
     }
 
+    /**
+     * Throws if caller doesn't hold the given lock.
+     * @param lock the lock
+     */
+    static void checkHoldsLock(Object lock) {
+        if (!Thread.holdsLock(lock)) {
+            throw new IllegalStateException("Caller doesn't hold global lock.");
+        }
+    }
+
     protected class TestActivityTaskManagerService extends ActivityTaskManagerService {
         // ActivityStackSupervisor may be created more than once while setting up AMS and ATMS.
         // We keep the reference in order to prevent creating it twice.
diff --git a/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java b/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java
index e5121b9297e61..77af5eec27963 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java
@@ -72,7 +72,7 @@ class TestDisplayContent extends DisplayContent {
         private final DisplayInfo mInfo;
         private boolean mCanRotate = true;
         private int mWindowingMode = WINDOWING_MODE_FULLSCREEN;
-        private int mPosition = POSITION_TOP;
+        private int mPosition = POSITION_BOTTOM;
         private final ActivityTaskManagerService mService;
         private boolean mSystemDecorations = false;
 
@@ -127,13 +127,13 @@ class TestDisplayContent extends DisplayContent {
             return this;
         }
         TestDisplayContent build() {
+            SystemServicesTestRule.checkHoldsLock(mService.mGlobalLock);
+
             final int displayId = SystemServicesTestRule.sNextDisplayId++;
             final Display display = new Display(DisplayManagerGlobal.getInstance(), displayId,
                     mInfo, DEFAULT_DISPLAY_ADJUSTMENTS);
-            final TestDisplayContent newDisplay;
-            synchronized (mService.mGlobalLock) {
-                newDisplay = new TestDisplayContent(mService.mStackSupervisor, display);
-            }
+            final TestDisplayContent newDisplay =
+                    new TestDisplayContent(mService.mStackSupervisor, display);
             // disable the normal system decorations
             final DisplayPolicy displayPolicy = newDisplay.mDisplayContent.getDisplayPolicy();
             spyOn(displayPolicy);
@@ -153,6 +153,10 @@ class TestDisplayContent extends DisplayContent {
                 doReturn(false).when(newDisplay.mDisplayContent)
                         .handlesOrientationChangeFromDescendant();
             }
+            // Please add stubbing before this line. Services will start using this display in other
+            // threads immediately after adding it to hierarchy. Calling doAnswer() type of stubbing
+            // reduces chance of races, but still doesn't eliminate race conditions.
+            mService.mRootWindowContainer.addChild(newDisplay, mPosition);
             return newDisplay;
         }
     }