diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 15795b0..cc3980c 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -673,10 +673,10 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
  * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require
  *		a relcache entry for the relation.
  *
- * NB: At present, this function may only be used on permanent relations, which
- * is OK, because we only use it during XLOG replay.  If in the future we
- * want to use it on temporary or unlogged relations, we could pass additional
- * parameters.
+ * NB: At present, this function may only be used on main fork pages of
+ * permanent relations and init fork pages, which is OK, because we only use
+ * it during XLOG replay.  If in the future we want to use it on temporary or
+ * unlogged relations, we could pass additional parameters.
  */
 Buffer
 ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
@@ -689,6 +689,10 @@ ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
 
 	Assert(InRecovery);
 
+	/*
+	 * Pages of init fork are permanent so RELPERSISTENCE_PERMANENT is ok
+	 * here.
+	 */
 	return ReadBuffer_common(smgr, RELPERSISTENCE_PERMANENT, forkNum, blockNum,
 							 mode, strategy, &hit);
 }