diff --git a/core/java/android/app/ApplicationExitInfo.java b/core/java/android/app/ApplicationExitInfo.java
index 60e22f4ecd12c..9bdddd037e21b 100644
--- a/core/java/android/app/ApplicationExitInfo.java
+++ b/core/java/android/app/ApplicationExitInfo.java
@@ -360,6 +360,53 @@ public final class ApplicationExitInfo implements Parcelable {
      */
     public static final int SUBREASON_FREEZER_BINDER_TRANSACTION = 20;
 
+    /**
+     * The process was killed because of force-stop, it could be due to that
+     * the user clicked the "Force stop" button of the application in the Settings;
+     * this would be set only when the reason is {@link #REASON_USER_REQUESTED}.
+     *
+     * For internal use only.
+     * @hide
+     */
+    public static final int SUBREASON_FORCE_STOP = 21;
+
+    /**
+     * The process was killed because the user removed the application away from Recents;
+     * this would be set only when the reason is {@link #REASON_USER_REQUESTED}.
+     *
+     * For internal use only.
+     * @hide
+     */
+    public static final int SUBREASON_REMOVE_TASK = 22;
+
+    /**
+     * The process was killed because the user stopped the application from the task manager;
+     * this would be set only when the reason is {@link #REASON_USER_REQUESTED}.
+     *
+     * For internal use only.
+     * @hide
+     */
+    public static final int SUBREASON_STOP_APP = 23;
+
+    /**
+     * The process was killed because the user stopped the application from developer options,
+     * or via the adb shell commmand interface; this would be set only when the reason is
+     * {@link #REASON_USER_REQUESTED}.
+     *
+     * For internal use only.
+     * @hide
+     */
+    public static final int SUBREASON_KILL_BACKGROUND = 24;
+
+    /**
+     * The process was killed because of package update; this would be set only when the reason is
+     * {@link #REASON_USER_REQUESTED}.
+     *
+     * For internal use only.
+     * @hide
+     */
+    public static final int SUBREASON_PACKAGE_UPDATE = 25;
+
     // If there is any OEM code which involves additional app kill reasons, it should
     // be categorized in {@link #REASON_OTHER}, with subreason code starting from 1000.
 
@@ -520,6 +567,11 @@ public final class ApplicationExitInfo implements Parcelable {
         SUBREASON_ISOLATED_NOT_NEEDED,
         SUBREASON_FREEZER_BINDER_IOCTL,
         SUBREASON_FREEZER_BINDER_TRANSACTION,
+        SUBREASON_FORCE_STOP,
+        SUBREASON_REMOVE_TASK,
+        SUBREASON_STOP_APP,
+        SUBREASON_KILL_BACKGROUND,
+        SUBREASON_PACKAGE_UPDATE,
     })
     @Retention(RetentionPolicy.SOURCE)
     public @interface SubReason {}
@@ -1193,6 +1245,16 @@ public final class ApplicationExitInfo implements Parcelable {
                 return "FREEZER BINDER IOCTL";
             case SUBREASON_FREEZER_BINDER_TRANSACTION:
                 return "FREEZER BINDER TRANSACTION";
+            case SUBREASON_FORCE_STOP:
+                return "FORCE STOP";
+            case SUBREASON_REMOVE_TASK:
+                return "REMOVE TASK";
+            case SUBREASON_STOP_APP:
+                return "STOP APP";
+            case SUBREASON_KILL_BACKGROUND:
+                return "KILL BACKGROUND";
+            case SUBREASON_PACKAGE_UPDATE:
+                return "PACKAGE UPDATE";
             default:
                 return "UNKNOWN";
         }
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 9512e1dafe7ea..95e35ef6cf323 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -3780,7 +3780,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                     synchronized (mProcLock) {
                         mProcessList.killPackageProcessesLSP(packageName, appId, targetUserId,
                                 ProcessList.SERVICE_ADJ, ApplicationExitInfo.REASON_USER_REQUESTED,
-                                ApplicationExitInfo.SUBREASON_UNKNOWN, "kill background");
+                                ApplicationExitInfo.SUBREASON_KILL_BACKGROUND, "kill background");
                     }
                 }
             }
@@ -3810,7 +3810,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                     mProcessList.killPackageProcessesLSP(null /* packageName */, -1 /* appId */,
                             UserHandle.USER_ALL, ProcessList.CACHED_APP_MIN_ADJ,
                             ApplicationExitInfo.REASON_USER_REQUESTED,
-                            ApplicationExitInfo.SUBREASON_UNKNOWN,
+                            ApplicationExitInfo.SUBREASON_KILL_BACKGROUND,
                             "kill all background");
                 }
 
@@ -4352,7 +4352,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                         ProcessList.INVALID_ADJ, true, false, true,
                         false, true /* setRemoved */, false,
                         ApplicationExitInfo.REASON_USER_REQUESTED,
-                        ApplicationExitInfo.SUBREASON_UNKNOWN,
+                        ApplicationExitInfo.SUBREASON_STOP_APP,
                         "fully stop " + packageName + "/" + userId + " by user request");
             }
 
@@ -4404,7 +4404,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                     evenPersistent, true /* setRemoved */, uninstalling,
                     packageName == null ? ApplicationExitInfo.REASON_USER_STOPPED
                     : ApplicationExitInfo.REASON_USER_REQUESTED,
-                    ApplicationExitInfo.SUBREASON_UNKNOWN,
+                    ApplicationExitInfo.SUBREASON_FORCE_STOP,
                     (packageName == null ? ("stop user " + userId) : ("stop " + packageName))
                     + " due to " + reason);
         }
@@ -13636,7 +13636,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                                                     UserHandle.getAppId(extraUid),
                                                     userId, ProcessList.INVALID_ADJ,
                                                     ApplicationExitInfo.REASON_USER_REQUESTED,
-                                                    ApplicationExitInfo.SUBREASON_UNKNOWN,
+                                                    ApplicationExitInfo.SUBREASON_PACKAGE_UPDATE,
                                                     "change " + ssp);
                                         }
                                     }
@@ -16365,7 +16365,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                     if (pr.mState.getSetSchedGroup() == ProcessList.SCHED_GROUP_BACKGROUND
                             && pr.mReceivers.numberOfCurReceivers() == 0) {
                         pr.killLocked("remove task", ApplicationExitInfo.REASON_USER_REQUESTED,
-                                ApplicationExitInfo.SUBREASON_UNKNOWN, true);
+                                ApplicationExitInfo.SUBREASON_REMOVE_TASK, true);
                     } else {
                         // We delay killing processes that are not in the background or running a
                         // receiver.
diff --git a/services/core/java/com/android/server/am/OomAdjuster.java b/services/core/java/com/android/server/am/OomAdjuster.java
index e0d333ee8f6a3..7ed3dcf40f65e 100644
--- a/services/core/java/com/android/server/am/OomAdjuster.java
+++ b/services/core/java/com/android/server/am/OomAdjuster.java
@@ -2561,7 +2561,7 @@ public class OomAdjuster {
             if (app.getWaitingToKill() != null && app.mReceivers.numberOfCurReceivers() == 0
                     && state.getSetSchedGroup() == ProcessList.SCHED_GROUP_BACKGROUND) {
                 app.killLocked(app.getWaitingToKill(), ApplicationExitInfo.REASON_USER_REQUESTED,
-                        ApplicationExitInfo.SUBREASON_UNKNOWN, true);
+                        ApplicationExitInfo.SUBREASON_REMOVE_TASK, true);
                 success = false;
             } else {
                 int processGroup;