Skip checkpoints in StartupCompletedTask when mutator-lock exclusively held

This could happen with semi-space GC.

Test: test.py
Bug: 282967538
Bug: 260557058
(cherry picked from https://android-review.googlesource.com/q/commit:b0e7f693312b6548ac1bf1edefe2dc4ef7810039)
Merged-In: Ib87c7ddb6b2ffa42e60a43a513f804fe0a6da24a
Change-Id: Ib87c7ddb6b2ffa42e60a43a513f804fe0a6da24a

1 files changed, 9 insertions, 2 deletions

diff --git a/runtime/startup_completed_task.cc b/runtime/startup_completed_task.cc
index d29889af75..9709965e9a 100644
--- a/runtime/startup_completed_task.cc
+++ b/runtime/startup_completed_task.cc
@@ -85,6 +85,9 @@ void StartupCompletedTask::DeleteStartupDexCaches(Thread* self, bool called_by_g
 
   // Fetch the startup linear alloc so no other thread tries to allocate there.
   std::unique_ptr<LinearAlloc> startup_linear_alloc(runtime->ReleaseStartupLinearAlloc());
+  // No thread could be allocating arrays or accessing dex caches when this
+  // thread has mutator-lock held exclusively.
+  bool run_checkpoints = !Locks::mutator_lock_->IsExclusiveHeld(self);
 
   // Request a checkpoint to make sure all threads see we have started up and
   // won't allocate in the startup linear alloc. Without this checkpoint what
@@ -96,7 +99,9 @@ void StartupCompletedTask::DeleteStartupDexCaches(Thread* self, bool called_by_g
   //
   // With this checkpoint, 3) cannot happen as T0 waits for T1 to reach the
   // checkpoint.
-  runtime->GetThreadList()->RunCheckpoint(&closure);
+  if (run_checkpoints) {
+    runtime->GetThreadList()->RunCheckpoint(&closure);
+  }
 
   {
     UnlinkStartupDexCacheVisitor visitor;
@@ -108,7 +113,9 @@ void StartupCompletedTask::DeleteStartupDexCaches(Thread* self, bool called_by_g
   // Request a checkpoint to make sure no threads are:
   // - accessing the image space metadata section when we madvise it
   // - accessing dex caches when we free them
-  runtime->GetThreadList()->RunCheckpoint(&closure);
+  if (run_checkpoints) {
+    runtime->GetThreadList()->RunCheckpoint(&closure);
+  }
 
   // If this isn't the GC calling `DeleteStartupDexCaches` and a GC may be
   // running, wait for it to be complete. We don't want it to see these dex