diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index f40b84592a6..39bcf844694 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -388,11 +388,11 @@ CreateInitDecodingContext(const char *plugin,
 	 * without further interlock its return value might immediately be out of
 	 * date.
 	 *
-	 * So we have to acquire the ProcArrayLock to prevent computation of new
-	 * xmin horizons by other backends, get the safe decoding xid, and inform
-	 * the slot machinery about the new limit. Once that's done the
-	 * ProcArrayLock can be released as the slot machinery now is
-	 * protecting against vacuum.
+	 * So we have to acquire both the ReplicationSlotControlLock and the
+	 * ProcArrayLock to prevent concurrent computation and update of new xmin
+	 * horizons by other backends, get the safe decoding xid, and inform the
+	 * slot machinery about the new limit. Once that's done both locks can be
+	 * released as the slot machinery now is protecting against vacuum.
 	 *
 	 * Note that, temporarily, the data, not just the catalog, xmin has to be
 	 * reserved if a data snapshot is to be exported.  Otherwise the initial
@@ -405,6 +405,7 @@ CreateInitDecodingContext(const char *plugin,
 	 *
 	 * ----
 	 */
+	LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
 	LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
 
 	xmin_horizon = GetOldestSafeDecodingTransactionId(!need_full_snapshot);
@@ -419,6 +420,7 @@ CreateInitDecodingContext(const char *plugin,
 	ReplicationSlotsComputeRequiredXmin(true);
 
 	LWLockRelease(ProcArrayLock);
+	LWLockRelease(ReplicationSlotControlLock);
 
 	ReplicationSlotMarkDirty();
 	ReplicationSlotSave();
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index c9eb1836a64..345e1bef4c8 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -788,8 +788,11 @@ ReplicationSlotPersist(void)
 /*
  * Compute the oldest xmin across all slots and store it in the ProcArray.
  *
- * If already_locked is true, ProcArrayLock has already been acquired
- * exclusively.
+ * If already_locked is true, both the ReplicationSlotControlLock and the
+ * ProcArrayLock have already been acquired exclusively. It is crucial that the
+ * caller first acquires the ReplicationSlotControlLock, followed by the
+ * ProcArrayLock, to prevent any undetectable deadlocks since this function
+ * acquires them in that order.
  */
 void
 ReplicationSlotsComputeRequiredXmin(bool already_locked)
@@ -799,8 +802,33 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
 	TransactionId agg_catalog_xmin = InvalidTransactionId;
 
 	Assert(ReplicationSlotCtl != NULL);
+	Assert(!already_locked ||
+		   (LWLockHeldByMeInMode(ReplicationSlotControlLock, LW_EXCLUSIVE) &&
+			LWLockHeldByMeInMode(ProcArrayLock, LW_EXCLUSIVE)));
 
-	LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
+	/*
+	 * Hold the ReplicationSlotControlLock until after updating the slot xmin
+	 * values, so no backend updates the initial xmin for newly created slot
+	 * concurrently. A shared lock is used here to minimize lock contention,
+	 * especially when many slots exist and advancements occur frequently.
+	 * This is safe since an exclusive lock is taken during initial slot xmin
+	 * update in slot creation.
+	 *
+	 * One might think that we can hold the ProcArrayLock exclusively and
+	 * update the slot xmin values, but it could increase lock contention on
+	 * the ProcArrayLock, which is not great since this function can be called
+	 * at non-negligible frequency.
+	 *
+	 * Concurrent invocation of this function may cause the computed slot xmin
+	 * to regress. However, this is harmless because tuples prior to the most
+	 * recent xmin are no longer useful once advancement occurs (see
+	 * LogicalConfirmReceivedLocation where the slot's xmin value is flushed
+	 * before updating the effective_xmin). Thus, such regression merely
+	 * prevents VACUUM from prematurely removing tuples without causing the
+	 * early deletion of required data.
+	 */
+	if (!already_locked)
+		LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
 
 	for (i = 0; i < max_replication_slots; i++)
 	{
@@ -836,9 +864,10 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
 			agg_catalog_xmin = effective_catalog_xmin;
 	}
 
-	LWLockRelease(ReplicationSlotControlLock);
-
 	ProcArraySetReplicationSlotXmin(agg_xmin, agg_catalog_xmin, already_locked);
+
+	if (!already_locked)
+		LWLockRelease(ReplicationSlotControlLock);
 }
 
 /*