diff --git a/services/core/java/com/android/server/job/JobSchedulerService.java b/services/core/java/com/android/server/job/JobSchedulerService.java
index b0d76e854af23..b8fe88439c2d8 100644
--- a/services/core/java/com/android/server/job/JobSchedulerService.java
+++ b/services/core/java/com/android/server/job/JobSchedulerService.java
@@ -524,7 +524,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
                                             Slog.d(TAG, "Removing jobs for package " + pkgName
                                                     + " in user " + userId);
                                         }
-                                        cancelJobsForUid(pkgUid);
+                                        cancelJobsForUid(pkgUid, "app package state changed");
                                     }
                                 } catch (RemoteException|IllegalArgumentException e) {
                                     /*
@@ -553,7 +553,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
                     if (DEBUG) {
                         Slog.d(TAG, "Removing jobs for uid: " + uidRemoved);
                     }
-                    cancelJobsForUid(uidRemoved);
+                    cancelJobsForUid(uidRemoved, "app uninstalled");
                 }
             } else if (Intent.ACTION_USER_REMOVED.equals(action)) {
                 final int userId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0);
@@ -611,7 +611,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
         @Override public void onUidGone(int uid, boolean disabled) throws RemoteException {
             updateUidState(uid, ActivityManager.PROCESS_STATE_CACHED_EMPTY);
             if (disabled) {
-                cancelJobsForUid(uid);
+                cancelJobsForUid(uid, "uid gone");
             }
         }
 
@@ -620,7 +620,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
 
         @Override public void onUidIdle(int uid, boolean disabled) throws RemoteException {
             if (disabled) {
-                cancelJobsForUid(uid);
+                cancelJobsForUid(uid, "app uid idle");
             }
         }
     };
@@ -689,7 +689,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
             jobStatus.prepareLocked(ActivityManager.getService());
 
             if (toCancel != null) {
-                cancelJobImplLocked(toCancel, jobStatus);
+                cancelJobImplLocked(toCancel, jobStatus, "job rescheduled by app");
             }
             if (work != null) {
                 // If work has been supplied, enqueue it into the new job.
@@ -747,7 +747,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
             final List<JobStatus> jobsForUser = mJobs.getJobsByUser(userHandle);
             for (int i=0; i<jobsForUser.size(); i++) {
                 JobStatus toRemove = jobsForUser.get(i);
-                cancelJobImplLocked(toRemove, null);
+                cancelJobImplLocked(toRemove, null, "user removed");
             }
         }
     }
@@ -765,7 +765,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
             for (int i = jobsForUid.size() - 1; i >= 0; i--) {
                 final JobStatus job = jobsForUid.get(i);
                 if (job.getSourcePackageName().equals(pkgName)) {
-                    cancelJobImplLocked(job, null);
+                    cancelJobImplLocked(job, null, "app force stopped");
                 }
             }
         }
@@ -778,12 +778,12 @@ public final class JobSchedulerService extends com.android.server.SystemService
      * @param uid Uid to check against for removal of a job.
      *
      */
-    public void cancelJobsForUid(int uid) {
+    public void cancelJobsForUid(int uid, String reason) {
         synchronized (mLock) {
             final List<JobStatus> jobsForUid = mJobs.getJobsByUid(uid);
             for (int i=0; i<jobsForUid.size(); i++) {
                 JobStatus toRemove = jobsForUid.get(i);
-                cancelJobImplLocked(toRemove, null);
+                cancelJobImplLocked(toRemove, null, reason);
             }
         }
     }
@@ -800,12 +800,12 @@ public final class JobSchedulerService extends com.android.server.SystemService
         synchronized (mLock) {
             toCancel = mJobs.getJobByUidAndJobId(uid, jobId);
             if (toCancel != null) {
-                cancelJobImplLocked(toCancel, null);
+                cancelJobImplLocked(toCancel, null, "cancel() called by app");
             }
         }
     }
 
-    private void cancelJobImplLocked(JobStatus cancelled, JobStatus incomingJob) {
+    private void cancelJobImplLocked(JobStatus cancelled, JobStatus incomingJob, String reason) {
         if (DEBUG) Slog.d(TAG, "CANCEL: " + cancelled.toShortString());
         cancelled.unprepareLocked(ActivityManager.getService());
         stopTrackingJobLocked(cancelled, incomingJob, true /* writeBack */);
@@ -814,7 +814,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
             mJobPackageTracker.noteNonpending(cancelled);
         }
         // Cancel if running.
-        stopJobOnServiceContextLocked(cancelled, JobParameters.REASON_CANCELED);
+        stopJobOnServiceContextLocked(cancelled, JobParameters.REASON_CANCELED, reason);
         reportActiveLocked();
     }
 
@@ -844,7 +844,8 @@ public final class JobSchedulerService extends com.android.server.SystemService
                     final JobStatus executing = jsc.getRunningJobLocked();
                     if (executing != null
                             && (executing.getFlags() & JobInfo.FLAG_WILL_BE_FOREGROUND) == 0) {
-                        jsc.cancelExecutingJobLocked(JobParameters.REASON_DEVICE_IDLE);
+                        jsc.cancelExecutingJobLocked(JobParameters.REASON_DEVICE_IDLE,
+                                "cancelled due to doze");
                     }
                 }
             } else {
@@ -1023,12 +1024,12 @@ public final class JobSchedulerService extends com.android.server.SystemService
         return removed;
     }
 
-    private boolean stopJobOnServiceContextLocked(JobStatus job, int reason) {
+    private boolean stopJobOnServiceContextLocked(JobStatus job, int reason, String debugReason) {
         for (int i=0; i<mActiveServices.size(); i++) {
             JobServiceContext jsc = mActiveServices.get(i);
             final JobStatus executing = jsc.getRunningJobLocked();
             if (executing != null && executing.matches(job.getUid(), job.getJobId())) {
-                jsc.cancelExecutingJobLocked(reason);
+                jsc.cancelExecutingJobLocked(reason, debugReason);
                 return true;
             }
         }
@@ -1270,7 +1271,8 @@ public final class JobSchedulerService extends com.android.server.SystemService
                         queueReadyJobsForExecutionLocked();
                         break;
                     case MSG_STOP_JOB:
-                        cancelJobImplLocked((JobStatus) message.obj, null);
+                        cancelJobImplLocked((JobStatus) message.obj, null,
+                                "app no longer allowed to run");
                         break;
                 }
                 maybeRunPendingJobsLocked();
@@ -1286,7 +1288,8 @@ public final class JobSchedulerService extends com.android.server.SystemService
             final JobStatus running = serviceContext.getRunningJobLocked();
             if (running != null && !running.isReady()) {
                 serviceContext.cancelExecutingJobLocked(
-                        JobParameters.REASON_CONSTRAINTS_NOT_SATISFIED);
+                        JobParameters.REASON_CONSTRAINTS_NOT_SATISFIED,
+                        "cancelled due to unsatisfied constraints");
             }
         }
     }
@@ -1960,7 +1963,7 @@ public final class JobSchedulerService extends com.android.server.SystemService
 
             long ident = Binder.clearCallingIdentity();
             try {
-                JobSchedulerService.this.cancelJobsForUid(uid);
+                JobSchedulerService.this.cancelJobsForUid(uid, "cancelAll() called by app");
             } finally {
                 Binder.restoreCallingIdentity(ident);
             }
@@ -2357,7 +2360,14 @@ public final class JobSchedulerService extends com.android.server.SystemService
                 pw.print("  Slot #"); pw.print(i); pw.print(": ");
                 final JobStatus job = jsc.getRunningJobLocked();
                 if (job == null) {
-                    pw.println("inactive");
+                    if (jsc.mStoppedReason != null) {
+                        pw.print("inactive since ");
+                        TimeUtils.formatDuration(jsc.mStoppedTime, nowElapsed, pw);
+                        pw.print(", stopped because: ");
+                        pw.println(jsc.mStoppedReason);
+                    } else {
+                        pw.println("inactive");
+                    }
                     continue;
                 } else {
                     pw.println(job.toShortString());
diff --git a/services/core/java/com/android/server/job/JobServiceContext.java b/services/core/java/com/android/server/job/JobServiceContext.java
index ff39baf36c2e4..637db11af6d8e 100644
--- a/services/core/java/com/android/server/job/JobServiceContext.java
+++ b/services/core/java/com/android/server/job/JobServiceContext.java
@@ -38,6 +38,7 @@ import android.os.SystemClock;
 import android.os.UserHandle;
 import android.os.WorkSource;
 import android.util.Slog;
+import android.util.TimeUtils;
 
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
@@ -126,6 +127,12 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
     /** Track when job will timeout. */
     private long mTimeoutElapsed;
 
+    // Debugging: reason this job was last stopped.
+    public String mStoppedReason;
+
+    // Debugging: time this job was last stopped.
+    public long mStoppedTime;
+
     JobServiceContext(JobSchedulerService service, IBatteryStats batteryStats,
             JobPackageTracker tracker, Looper looper) {
         this(service.getContext(), service.getLock(), batteryStats, tracker, service, looper);
@@ -204,6 +211,8 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
             }
             mJobPackageTracker.noteActive(job);
             mAvailable = false;
+            mStoppedReason = null;
+            mStoppedTime = 0;
             return true;
         }
     }
@@ -216,12 +225,12 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
     }
 
     /** Called externally when a job that was scheduled for execution should be cancelled. */
-    void cancelExecutingJobLocked(int reason) {
-        doCancelLocked(reason);
+    void cancelExecutingJobLocked(int reason, String debugReason) {
+        doCancelLocked(reason, debugReason);
     }
 
     void preemptExecutingJobLocked() {
-        doCancelLocked(JobParameters.REASON_PREEMPT);
+        doCancelLocked(JobParameters.REASON_PREEMPT, "cancelled due to preemption");
     }
 
     int getPreferredUid() {
@@ -247,7 +256,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
                 && (!matchJobId || jobId == executing.getJobId())) {
             if (mVerb == VERB_EXECUTING) {
                 mParams.setStopReason(JobParameters.REASON_TIMEOUT);
-                sendStopMessageLocked();
+                sendStopMessageLocked("force timeout from shell");
                 return true;
             }
         }
@@ -256,17 +265,17 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
 
     @Override
     public void jobFinished(int jobId, boolean reschedule) {
-        doCallback(reschedule);
+        doCallback(reschedule, "app called jobFinished");
     }
 
     @Override
     public void acknowledgeStopMessage(int jobId, boolean reschedule) {
-        doCallback(reschedule);
+        doCallback(reschedule, null);
     }
 
     @Override
     public void acknowledgeStartMessage(int jobId, boolean ongoing) {
-        doCallback(ongoing);
+        doCallback(ongoing, "finished start");
     }
 
     @Override
@@ -275,14 +284,11 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         final long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mLock) {
-                if (!verifyCallingUidLocked(callingUid)) {
-                    throw new SecurityException("Bad calling uid: " + callingUid);
-                }
-
+                assertCallingUidLocked(callingUid);
                 final JobWorkItem work = mRunningJob.dequeueWorkLocked();
                 if (work == null && !mRunningJob.hasExecutingWorkLocked()) {
                     // This will finish the job.
-                    doCallbackLocked(false);
+                    doCallbackLocked(false, "last work dequeued");
                 }
                 return work;
             }
@@ -297,9 +303,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         final long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mLock) {
-                if (!verifyCallingUidLocked(callingUid)) {
-                    throw new SecurityException("Bad calling uid: " + callingUid);
-                }
+                assertCallingUidLocked(callingUid);
                 return mRunningJob.completeWorkLocked(ActivityManager.getService(), workId);
             }
         } finally {
@@ -324,7 +328,8 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
             runningJob = mRunningJob;
 
             if (runningJob == null || !name.equals(runningJob.getServiceComponent())) {
-                closeAndCleanupJobLocked(true /* needsReschedule */);
+                closeAndCleanupJobLocked(true /* needsReschedule */,
+                        "connected for different component");
                 return;
             }
             this.service = IJobService.Stub.asInterface(service);
@@ -355,7 +360,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
     @Override
     public void onServiceDisconnected(ComponentName name) {
         synchronized (mLock) {
-            closeAndCleanupJobLocked(true /* needsReschedule */);
+            closeAndCleanupJobLocked(true /* needsReschedule */, "unexpectedly disconnected");
         }
     }
 
@@ -374,6 +379,21 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         return true;
     }
 
+    private void assertCallingUidLocked(final int callingUid) {
+        if (!verifyCallingUidLocked(callingUid)) {
+            StringBuilder sb = new StringBuilder(128);
+            sb.append("Bad calling uid ");
+            sb.append(callingUid);
+            if (mStoppedReason != null) {
+                sb.append(", last stopped ");
+                TimeUtils.formatDuration(SystemClock.elapsedRealtime() - mStoppedTime, sb);
+                sb.append(" because: ");
+                sb.append(mStoppedReason);
+            }
+            throw new SecurityException(sb.toString());
+        }
+    }
+
     /**
      * Scheduling of async messages (basically timeouts at this point).
      */
@@ -401,7 +421,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         handleServiceBoundLocked();
     }
 
-    void doCallback(boolean reschedule) {
+    void doCallback(boolean reschedule, String reason) {
         final int callingUid = Binder.getCallingUid();
         final long ident = Binder.clearCallingIdentity();
         try {
@@ -409,14 +429,14 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
                 if (!verifyCallingUidLocked(callingUid)) {
                     return;
                 }
-                doCallbackLocked(reschedule);
+                doCallbackLocked(reschedule, reason);
             }
         } finally {
             Binder.restoreCallingIdentity(ident);
         }
     }
 
-    void doCallbackLocked(boolean reschedule) {
+    void doCallbackLocked(boolean reschedule, String reason) {
         if (DEBUG) {
             Slog.d(TAG, "doCallback of : " + mRunningJob
                     + " v:" + VERB_STRINGS[mVerb]);
@@ -427,7 +447,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
             handleStartedLocked(reschedule);
         } else if (mVerb == VERB_EXECUTING ||
                 mVerb == VERB_STOPPING) {
-            handleFinishedLocked(reschedule);
+            handleFinishedLocked(reschedule, reason);
         } else {
             if (DEBUG) {
                 Slog.d(TAG, "Unrecognised callback: " + mRunningJob);
@@ -435,7 +455,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         }
     }
 
-    void doCancelLocked(int arg1) {
+    void doCancelLocked(int arg1, String debugReason) {
         if (mVerb == VERB_FINISHED) {
             if (DEBUG) {
                 Slog.d(TAG,
@@ -448,7 +468,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
             mPreferredUid = mRunningJob != null ? mRunningJob.getUid() :
                     NO_PREFERRED_UID;
         }
-        handleCancelLocked();
+        handleCancelLocked(debugReason);
     }
 
     /** Start the job on the service. */
@@ -459,7 +479,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         if (mVerb != VERB_BINDING) {
             Slog.e(TAG, "Sending onStartJob for a job that isn't pending. "
                     + VERB_STRINGS[mVerb]);
-            closeAndCleanupJobLocked(false /* reschedule */);
+            closeAndCleanupJobLocked(false /* reschedule */, "started job not pending");
             return;
         }
         if (mCancelled) {
@@ -467,7 +487,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
                 Slog.d(TAG, "Job cancelled while waiting for bind to complete. "
                         + mRunningJob);
             }
-            closeAndCleanupJobLocked(true /* reschedule */);
+            closeAndCleanupJobLocked(true /* reschedule */, "cancelled while waiting for bind");
             return;
         }
         try {
@@ -496,7 +516,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
                 mVerb = VERB_EXECUTING;
                 if (!workOngoing) {
                     // Job is finished already so fast-forward to handleFinished.
-                    handleFinishedLocked(false);
+                    handleFinishedLocked(false, "onStartJob returned false");
                     return;
                 }
                 if (mCancelled) {
@@ -504,7 +524,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
                         Slog.d(TAG, "Job cancelled while waiting for onStartJob to complete.");
                     }
                     // Cancelled *while* waiting for acknowledgeStartMessage from client.
-                    handleCancelLocked();
+                    handleCancelLocked(null);
                     return;
                 }
                 scheduleOpTimeOutLocked();
@@ -522,11 +542,11 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
      *     _STARTING   -> Error
      *     _PENDING    -> Error
      */
-    private void handleFinishedLocked(boolean reschedule) {
+    private void handleFinishedLocked(boolean reschedule, String reason) {
         switch (mVerb) {
             case VERB_EXECUTING:
             case VERB_STOPPING:
-                closeAndCleanupJobLocked(reschedule);
+                closeAndCleanupJobLocked(reschedule, reason);
                 break;
             default:
                 Slog.e(TAG, "Got an execution complete message for a job that wasn't being" +
@@ -544,7 +564,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
      *                      in the message queue.
      *     _ENDING     -> No point in doing anything here, so we ignore.
      */
-    private void handleCancelLocked() {
+    private void handleCancelLocked(String reason) {
         if (JobSchedulerService.DEBUG) {
             Slog.d(TAG, "Handling cancel for: " + mRunningJob.getJobId() + " "
                     + VERB_STRINGS[mVerb]);
@@ -553,9 +573,10 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
             case VERB_BINDING:
             case VERB_STARTING:
                 mCancelled = true;
+                applyStoppedReasonLocked(reason);
                 break;
             case VERB_EXECUTING:
-                sendStopMessageLocked();
+                sendStopMessageLocked(reason);
                 break;
             case VERB_STOPPING:
                 // Nada.
@@ -572,7 +593,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
             case VERB_BINDING:
                 Slog.e(TAG, "Time-out while trying to bind " + mRunningJob.toShortString() +
                         ", dropping.");
-                closeAndCleanupJobLocked(false /* needsReschedule */);
+                closeAndCleanupJobLocked(false /* needsReschedule */, "timed out while binding");
                 break;
             case VERB_STARTING:
                 // Client unresponsive - wedged or failed to respond in time. We don't really
@@ -580,25 +601,25 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
                 // FINISHED/NO-RETRY.
                 Slog.e(TAG, "No response from client for onStartJob '" +
                         mRunningJob.toShortString());
-                closeAndCleanupJobLocked(false /* needsReschedule */);
+                closeAndCleanupJobLocked(false /* needsReschedule */, "timed out while starting");
                 break;
             case VERB_STOPPING:
                 // At least we got somewhere, so fail but ask the JobScheduler to reschedule.
                 Slog.e(TAG, "No response from client for onStopJob, '" +
                         mRunningJob.toShortString());
-                closeAndCleanupJobLocked(true /* needsReschedule */);
+                closeAndCleanupJobLocked(true /* needsReschedule */, "timed out while stopping");
                 break;
             case VERB_EXECUTING:
                 // Not an error - client ran out of time.
                 Slog.i(TAG, "Client timed out while executing (no jobFinished received)." +
                         " sending onStop. "  + mRunningJob.toShortString());
                 mParams.setStopReason(JobParameters.REASON_TIMEOUT);
-                sendStopMessageLocked();
+                sendStopMessageLocked("timeout while executing");
                 break;
             default:
                 Slog.e(TAG, "Handling timeout for an invalid job state: " +
                         mRunningJob.toShortString() + ", dropping.");
-                closeAndCleanupJobLocked(false /* needsReschedule */);
+                closeAndCleanupJobLocked(false /* needsReschedule */, "invalid timeout");
         }
     }
 
@@ -606,11 +627,11 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
      * Already running, need to stop. Will switch {@link #mVerb} from VERB_EXECUTING ->
      * VERB_STOPPING.
      */
-    private void sendStopMessageLocked() {
+    private void sendStopMessageLocked(String reason) {
         removeOpTimeOutLocked();
         if (mVerb != VERB_EXECUTING) {
             Slog.e(TAG, "Sending onStopJob for a job that isn't started. " + mRunningJob);
-            closeAndCleanupJobLocked(false /* reschedule */);
+            closeAndCleanupJobLocked(false /* reschedule */, reason);
             return;
         }
         try {
@@ -620,7 +641,7 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         } catch (RemoteException e) {
             Slog.e(TAG, "Error sending onStopJob to client.", e);
             // The job's host app apparently crashed during the job, so we should reschedule.
-            closeAndCleanupJobLocked(true /* reschedule */);
+            closeAndCleanupJobLocked(true /* reschedule */, "host crashed when trying to stop");
         }
     }
 
@@ -630,11 +651,12 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
      * or from acknowledging the stop message we sent. Either way, we're done tracking it and
      * we want to clean up internally.
      */
-    private void closeAndCleanupJobLocked(boolean reschedule) {
+    private void closeAndCleanupJobLocked(boolean reschedule, String reason) {
         final JobStatus completedJob;
         if (mVerb == VERB_FINISHED) {
             return;
         }
+        applyStoppedReasonLocked(reason);
         completedJob = mRunningJob;
         mJobPackageTracker.noteInactive(completedJob);
         try {
@@ -658,6 +680,13 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         mCompletedListener.onJobCompletedLocked(completedJob, reschedule);
     }
 
+    private void applyStoppedReasonLocked(String reason) {
+        if (reason != null && mStoppedReason == null) {
+            mStoppedReason = reason;
+            mStoppedTime = SystemClock.elapsedRealtime();
+        }
+    }
+
     /**
      * Called when sending a message to the client, over whose execution we have no control. If
      * we haven't received a response in a certain amount of time, we want to give up and carry