4 files changed, 11 insertions, 0 deletions
diff --git a/runtime/debugger.cc b/runtime/debugger.cc
index d8325525ac..55f68d3f2c 100644
--- a/runtime/debugger.cc
+++ b/runtime/debugger.cc
@@ -2362,6 +2362,10 @@ JDWP::ObjectId Dbg::GetThreadId(Thread* thread) {
 }
 
 void Dbg::SuspendVM() {
+  // Avoid a deadlock between GC and debugger where GC gets suspended during GC. b/25800335.
+  gc::ScopedGCCriticalSection gcs(Thread::Current(),
+                                  gc::kGcCauseDebugger,
+                                  gc::kCollectorTypeDebugger);
   Runtime::Current()->GetThreadList()->SuspendAllForDebugger();
 }
 
@@ -4101,6 +4105,8 @@ void Dbg::ExecuteMethodWithoutPendingException(ScopedObjectAccess& soa, DebugInv
   // Suspend other threads if the invoke is not single-threaded.
   if ((pReq->options & JDWP::INVOKE_SINGLE_THREADED) == 0) {
     ScopedThreadSuspension sts(soa.Self(), kWaitingForDebuggerSuspension);
+    // Avoid a deadlock between GC and debugger where GC gets suspended during GC. b/25800335.
+    gc::ScopedGCCriticalSection gcs(soa.Self(), gc::kGcCauseDebugger, gc::kCollectorTypeDebugger);
     VLOG(jdwp) << "      Suspending all threads";
     Runtime::Current()->GetThreadList()->SuspendAllForDebugger();
   }
diff --git a/runtime/gc/collector_type.h b/runtime/gc/collector_type.h
index ae412262fc..4ffc8afd09 100644
--- a/runtime/gc/collector_type.h
+++ b/runtime/gc/collector_type.h
@@ -44,6 +44,8 @@ enum CollectorType {
   kCollectorTypeInstrumentation,
   // Fake collector for adding or removing application image spaces.
   kCollectorTypeAddRemoveAppImageSpace,
+  // Fake collector used to implement exclusion between GC and debugger.
+  kCollectorTypeDebugger,
   // A homogeneous space compaction collector used in background transition
   // when both foreground and background collector are CMS.
   kCollectorTypeHomogeneousSpaceCompact,
diff --git a/runtime/gc/gc_cause.cc b/runtime/gc/gc_cause.cc
index 679432ba89..18e5703fcf 100644
--- a/runtime/gc/gc_cause.cc
+++ b/runtime/gc/gc_cause.cc
@@ -35,6 +35,7 @@ const char* PrettyCause(GcCause cause) {
     case kGcCauseTrim: return "HeapTrim";
     case kGcCauseInstrumentation: return "Instrumentation";
     case kGcCauseAddRemoveAppImageSpace: return "AddRemoveAppImageSpace";
+    case kGcCauseDebugger: return "Debugger";
     default:
       LOG(FATAL) << "Unreachable";
       UNREACHABLE();
diff --git a/runtime/gc/gc_cause.h b/runtime/gc/gc_cause.h
index c6b505c481..ad67eb7ebc 100644
--- a/runtime/gc/gc_cause.h
+++ b/runtime/gc/gc_cause.h
@@ -43,6 +43,8 @@ enum GcCause {
   kGcCauseInstrumentation,
   // Not a real GC cause, used to add or remove app image spaces.
   kGcCauseAddRemoveAppImageSpace,
+  // Not a real GC cause, used to implement exclusion between GC and debugger.
+  kGcCauseDebugger,
   // GC triggered for background transition when both foreground and background collector are CMS.
   kGcCauseHomogeneousSpaceCompact,
 };