diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 885558f291..a30314bc83 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -8714,6 +8714,14 @@ CreateCheckPoint(int flags)
 	MemSet(&CheckpointStats, 0, sizeof(CheckpointStats));
 	CheckpointStats.ckpt_start_t = GetCurrentTimestamp();
 
+	/*
+	 * Let smgr prepare for checkpoint; this has to happen outside the
+	 * critical section and before we determine the REDO pointer.  Note that
+	 * smgr must not do anything that'd have to be undone if we decide no
+	 * checkpoint is needed.
+	 */
+	SyncPreCheckpoint();
+
 	/*
 	 * Use a critical section to force system panic if we have trouble.
 	 */
@@ -8728,13 +8736,6 @@ CreateCheckPoint(int flags)
 		LWLockRelease(ControlFileLock);
 	}
 
-	/*
-	 * Let smgr prepare for checkpoint; this has to happen before we determine
-	 * the REDO pointer.  Note that smgr must not do anything that'd have to
-	 * be undone if we decide no checkpoint is needed.
-	 */
-	SyncPreCheckpoint();
-
 	/* Begin filling in the checkpoint WAL record */
 	MemSet(&checkPoint, 0, sizeof(checkPoint));
 	checkPoint.time = (pg_time_t) time(NULL);
diff --git a/src/backend/storage/sync/sync.c b/src/backend/storage/sync/sync.c
index a67dc591e0..fce2093bea 100644
--- a/src/backend/storage/sync/sync.c
+++ b/src/backend/storage/sync/sync.c
@@ -151,7 +151,9 @@ InitSync(void)
  * counter is incremented here.
  *
  * This must be called *before* the checkpoint REDO point is determined.
- * That ensures that we won't delete files too soon.
+ * That ensures that we won't delete files too soon.  Since this calls
+ * AbsorbSyncRequests(), which performs memory allocations, it cannot be
+ * called within a critical section.
  *
  * Note that we can't do anything here that depends on the assumption
  * that the checkpoint will be completed.
@@ -159,6 +161,16 @@ InitSync(void)
 void
 SyncPreCheckpoint(void)
 {
+	/*
+	 * Operations such as DROP TABLESPACE assume that the next checkpoint will
+	 * process all recently forwarded unlink requests, but if they aren't
+	 * absorbed prior to advancing the cycle counter, they won't be processed
+	 * until a future checkpoint.  The following absorb ensures that any
+	 * unlink requests forwarded before the checkpoint began will be processed
+	 * in the current checkpoint.
+	 */
+	AbsorbSyncRequests();
+
 	/*
 	 * Any unlink requests arriving after this point will be assigned the next
 	 * cycle counter, and won't be unlinked until next checkpoint.