diff --git a/db/db_impl.cc b/db/db_impl.cc
index f17d70290..97354ca5a 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -1026,10 +1026,13 @@ int DBImpl::FindMinimumEmptyLevelFitting(
 
 Status DBImpl::FlushWAL(bool sync) {
   if (manual_wal_flush_) {
-    // We need to lock log_write_mutex_ since logs_ might change concurrently
-    InstrumentedMutexLock wl(&log_write_mutex_);
-    log::Writer* cur_log_writer = logs_.back().writer;
-    auto s = cur_log_writer->WriteBuffer();
+    Status s;
+    {
+      // We need to lock log_write_mutex_ since logs_ might change concurrently
+      InstrumentedMutexLock wl(&log_write_mutex_);
+      log::Writer* cur_log_writer = logs_.back().writer;
+      s = cur_log_writer->WriteBuffer();
+    }
     if (!s.ok()) {
       ROCKS_LOG_ERROR(immutable_db_options_.info_log, "WAL flush error %s",
                       s.ToString().c_str());
diff --git a/db/db_impl.h b/db/db_impl.h
index ce90ab25e..53f42e20b 100644
--- a/db/db_impl.h
+++ b/db/db_impl.h
@@ -1261,6 +1261,8 @@ class DBImpl : public DB {
   // logfile_number_. With two_write_queues it also protects alive_log_files_,
   // and log_empty_. Refer to the definition of each variable below for more
   // details.
+  // Note: to avoid dealock, if needed to acquire both log_write_mutex_ and
+  // mutex_, the order should be first mutex_ and then log_write_mutex_.
   InstrumentedMutex log_write_mutex_;
 
   std::atomic<bool> shutting_down_;