diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 88146008b3e36f..d45ceb2e21492d 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -451,7 +451,6 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	}
 	spin_unlock(&commit_transaction->t_handle_lock);
 	commit_transaction->t_state = T_SWITCH;
-	write_unlock(&journal->j_state_lock);
 
 	J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 			journal->j_max_transaction_buffers);
@@ -471,6 +470,8 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	 * has reserved.  This is consistent with the existing behaviour
 	 * that multiple jbd2_journal_get_write_access() calls to the same
 	 * buffer are perfectly permissible.
+	 * We use journal->j_state_lock here to serialize processing of
+	 * t_reserved_list with eviction of buffers from journal_unmap_buffer().
 	 */
 	while (commit_transaction->t_reserved_list) {
 		jh = commit_transaction->t_reserved_list;
@@ -490,6 +491,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 		jbd2_journal_refile_buffer(journal, jh);
 	}
 
+	write_unlock(&journal->j_state_lock);
 	/*
 	 * Now try to drop any written-back buffers from the journal's
 	 * checkpoint lists.  We do this *before* commit because it potentially