diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c
index e152807d2d..7479212d4e 100644
--- a/src/backend/access/heap/hio.c
+++ b/src/backend/access/heap/hio.c
@@ -623,6 +623,13 @@ loop:
 	 */
 	buffer = ReadBufferBI(relation, P_NEW, RBM_ZERO_AND_LOCK, bistate);
 
+	/*
+	 * Release the file-extension lock; it's now OK for someone else to extend
+	 * the relation some more.
+	 */
+	if (needLock)
+		UnlockRelationForExtension(relation, ExclusiveLock);
+
 	/*
 	 * We need to initialize the empty new page.  Double-check that it really
 	 * is empty (this should never happen, but if it does we don't want to
@@ -647,13 +654,6 @@ loop:
 		visibilitymap_pin(relation, BufferGetBlockNumber(buffer), vmbuffer);
 	}
 
-	/*
-	 * Release the file-extension lock; it's now OK for someone else to extend
-	 * the relation some more.
-	 */
-	if (needLock)
-		UnlockRelationForExtension(relation, ExclusiveLock);
-
 	/*
 	 * Lock the other buffer. It's guaranteed to be of a lower page number
 	 * than the new page. To conform with the deadlock prevent rules, we ought