diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 2a0dcc31945..47c01ed7271 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -997,6 +997,9 @@ mdnblocks(SMgrRelation reln, ForkNumber forknum)
  * functions for this relation or handled interrupts in between.  This makes
  * sure we have opened all active segments, so that truncate loop will get
  * them all!
+ *
+ * If nblocks > curnblk, the request is ignored when we are InRecovery,
+ * otherwise, an error is raised.
  */
 void
 mdtruncate(SMgrRelation reln, ForkNumber forknum,
diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index f203c2e9efb..b9a95b00467 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -713,11 +713,20 @@ smgrtruncate2(SMgrRelation reln, ForkNumber *forknum, int nforks,
 		/*
 		 * We might as well update the local smgr_cached_nblocks values. The
 		 * smgr cache inval message that this function sent will cause other
-		 * backends to invalidate their copies of smgr_fsm_nblocks and
-		 * smgr_vm_nblocks, and these ones too at the next command boundary.
-		 * But these ensure they aren't outright wrong until then.
+		 * backends to invalidate their copies of smgr_cached_nblocks, and
+		 * these ones too at the next command boundary. But ensure they aren't
+		 * outright wrong until then.
+		 *
+		 * We can have nblocks > old_nblocks when a relation was truncated
+		 * multiple times, a replica applied all the truncations, and later
+		 * restarts from a restartpoint located before the truncations. The
+		 * relation on disk will be the size of the last truncate. When
+		 * replaying the first truncate, we will have nblocks > current size.
+		 * In such cases, smgr_truncate does nothing, so set the cached size
+		 * to the old size rather than the requested size.
 		 */
-		reln->smgr_cached_nblocks[forknum[i]] = nblocks[i];
+		reln->smgr_cached_nblocks[forknum[i]] =
+			nblocks[i] > old_nblocks[i] ? old_nblocks[i] : nblocks[i];
 	}
 }