diff --git a/src/backend/utils/mmgr/dsa.c b/src/backend/utils/mmgr/dsa.c
index 9ed9fa3a661..e503575be62 100644
--- a/src/backend/utils/mmgr/dsa.c
+++ b/src/backend/utils/mmgr/dsa.c
@@ -693,7 +693,18 @@ dsa_allocate_extended(dsa_area *area, size_t size, int flags)
 		/* Obtain a span object. */
 		span_pointer = alloc_object(area, DSA_SCLASS_BLOCK_OF_SPANS);
 		if (!DsaPointerIsValid(span_pointer))
+		{
+			/* Raise error unless asked not to. */
+			if ((flags & DSA_ALLOC_NO_OOM) == 0)
+			{
+				ereport(ERROR,
+						(errcode(ERRCODE_OUT_OF_MEMORY),
+						 errmsg("out of memory"),
+						 errdetail("Failed on DSA request of size %zu.",
+								   size)));
+			}
 			return InvalidDsaPointer;
+		}
 
 		LWLockAcquire(DSA_AREA_LOCK(area), LW_EXCLUSIVE);
 
@@ -1669,13 +1680,14 @@ ensure_active_superblock(dsa_area *area, dsa_area_pool *pool,
 			return false;
 		}
 	}
+	/*
+	 * This shouldn't happen: get_best_segment() or make_new_segment()
+	 * promised that we can successfully allocate npages.
+	 */
 	if (!FreePageManagerGet(segment_map->fpm, npages, &first_page))
-	{
-		LWLockRelease(DSA_AREA_LOCK(area));
-		if (size_class != DSA_SCLASS_BLOCK_OF_SPANS)
-			dsa_free(area, span_pointer);
-		return false;
-	}
+		elog(FATAL,
+			 "dsa_allocate could not find %zu free pages for superblock",
+			 npages);
 	LWLockRelease(DSA_AREA_LOCK(area));
 
 	/* Compute the start of the superblock. */