diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index c33438c4bbd..b082cc80f6c 100644
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -1568,6 +1568,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum,
 
 	Assert(!P_IGNORE(opaque));
 	Assert(BTScanPosIsPinned(so->currPos));
+	Assert(!so->needPrimScan);
 
 	if (scan->parallel_scan)
 	{
@@ -1594,7 +1595,6 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum,
 	maxoff = PageGetMaxOffsetNumber(page);
 
 	/* initialize page-level state that we'll pass to _bt_checkkeys */
-	pstate.dir = dir;
 	pstate.minoff = minoff;
 	pstate.maxoff = maxoff;
 	pstate.finaltup = NULL;
@@ -2088,7 +2088,7 @@ _bt_steppage(IndexScanDesc scan, ScanDirection dir)
 		 */
 		if (so->needPrimScan)
 		{
-			if (ScanDirectionIsForward(dir))
+			if (ScanDirectionIsForward(so->currPos.dir))
 				so->markPos.moreRight = true;
 			else
 				so->markPos.moreLeft = true;
@@ -2109,6 +2109,15 @@ _bt_steppage(IndexScanDesc scan, ScanDirection dir)
 		else
 			blkno = so->currPos.prevPage;
 		lastcurrblkno = so->currPos.currPage;
+
+		/*
+		 * Cancel primitive index scans that were scheduled when the call to
+		 * _bt_readpage for currPos happened to use the opposite direction to
+		 * the one that we're stepping in now.  (It's okay to leave the scan's
+		 * array keys as-is, since the next _bt_readpage will advance them.)
+		 */
+		if (so->currPos.dir != dir)
+			so->needPrimScan = false;
 	}
 	else
 	{
@@ -2118,6 +2127,8 @@ _bt_steppage(IndexScanDesc scan, ScanDirection dir)
 		 */
 		if (!_bt_parallel_seize(scan, &blkno, &lastcurrblkno, false))
 			return false;
+
+		Assert(!so->needPrimScan);
 	}
 
 	return _bt_readnextpage(scan, blkno, lastcurrblkno, dir);
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 76be65123c8..20227989c6d 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -1800,7 +1800,7 @@ _bt_advance_array_keys(IndexScanDesc scan, BTReadPageState *pstate,
 {
 	BTScanOpaque so = (BTScanOpaque) scan->opaque;
 	Relation	rel = scan->indexRelation;
-	ScanDirection dir = pstate ? pstate->dir : ForwardScanDirection;
+	ScanDirection dir = so->currPos.dir;
 	int			arrayidx = 0;
 	bool		beyond_end_advance = false,
 				has_required_opposite_direction_only = false,
@@ -2400,8 +2400,10 @@ new_prim_scan:
 	/*
 	 * End this primitive index scan, but schedule another.
 	 *
-	 * Note: If the scan direction happens to change, this scheduled primitive
-	 * index scan won't go ahead after all.
+	 * Note: We make a soft assumption that the current scan direction will
+	 * also be used within _bt_next, when it is asked to step off this page.
+	 * It is up to _bt_next to cancel this scheduled primitive index scan
+	 * whenever it steps to a page in the direction opposite currPos.dir.
 	 */
 	pstate->continuescan = false;	/* Tell _bt_readpage we're done... */
 	so->needPrimScan = true;	/* ...but call _bt_first again */
@@ -3458,7 +3460,7 @@ _bt_checkkeys(IndexScanDesc scan, BTReadPageState *pstate, bool arrayKeys,
 {
 	TupleDesc	tupdesc = RelationGetDescr(scan->indexRelation);
 	BTScanOpaque so = (BTScanOpaque) scan->opaque;
-	ScanDirection dir = pstate->dir;
+	ScanDirection dir = so->currPos.dir;
 	int			ikey = 0;
 	bool		res;
 
@@ -4062,7 +4064,8 @@ static void
 _bt_checkkeys_look_ahead(IndexScanDesc scan, BTReadPageState *pstate,
 						 int tupnatts, TupleDesc tupdesc)
 {
-	ScanDirection dir = pstate->dir;
+	BTScanOpaque so = (BTScanOpaque) scan->opaque;
+	ScanDirection dir = so->currPos.dir;
 	OffsetNumber aheadoffnum;
 	IndexTuple	ahead;
 
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 5fb523ecec3..123fba624db 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -1078,7 +1078,6 @@ typedef BTScanOpaqueData *BTScanOpaque;
 typedef struct BTReadPageState
 {
 	/* Input parameters, set by _bt_readpage for _bt_checkkeys */
-	ScanDirection dir;			/* current scan direction */
 	OffsetNumber minoff;		/* Lowest non-pivot tuple's offset */
 	OffsetNumber maxoff;		/* Highest non-pivot tuple's offset */
 	IndexTuple	finaltup;		/* Needed by scans with array keys */