--- /dev/null
+From 05ed733b65ab977dd931e7f7ac0f62fdb81205c2 Mon Sep 17 00:00:00 2001
+From: Xingquan Liu <b1n@b1n.io>
+Date: Fri, 19 Jun 2026 11:13:47 -0400
+Subject: net/sched: dualpi2: fix GSO backlog accounting
+
+From: Xingquan Liu <b1n@b1n.io>
+
+commit 05ed733b65ab977dd931e7f7ac0f62fdb81205c2 upstream.
+
+When DualPI2 splits a GSO skb into N segments, it propagates N
+additional packets to its parent before returning NET_XMIT_SUCCESS.
+The parent then accounts for the original skb once more, leaving its
+qlen one larger than the number of packets actually queued.
+
+With QFQ as the parent, after all real packets are dequeued, QFQ still
+has a non-zero qlen while its in-service aggregate has no active
+classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes
+the result to qfq_peek_skb(), causing a NULL pointer dereference.
+
+Follow the same pattern used by tbf_segment() and taprio: count only
+successfully queued segments, propagate the difference between the
+original skb and those segments, and return NET_XMIT_SUCCESS whenever
+at least one segment was queued.
+
+Fixes: 8f9516daedd6 ("sched: Add enqueue/dequeue of dualpi2 qdisc")
+Cc: stable@vger.kernel.org
+Signed-off-by: Xingquan Liu <b1n@b1n.io>
+Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
+Reviewed-by: Victor Nogueira <victor@mojatatu.com>
+Link: https://patch.msgid.link/20260619151447.223640-1-b1n@b1n.io
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ net/sched/sch_dualpi2.c | 11 +++++------
+ 1 file changed, 5 insertions(+), 6 deletions(-)
+
+--- a/net/sched/sch_dualpi2.c
++++ b/net/sched/sch_dualpi2.c
+@@ -461,7 +461,7 @@ static int dualpi2_qdisc_enqueue(struct
+ if (IS_ERR_OR_NULL(nskb))
+ return qdisc_drop(skb, sch, to_free);
+
+- cnt = 1;
++ cnt = 0;
+ byte_len = 0;
+ orig_len = qdisc_pkt_len(skb);
+ skb_list_walk_safe(nskb, nskb, next) {
+@@ -488,16 +488,15 @@ static int dualpi2_qdisc_enqueue(struct
+ byte_len += nskb->len;
+ }
+ }
+- if (cnt > 1) {
++ if (cnt > 0) {
+ /* The caller will add the original skb stats to its
+ * backlog, compensate this if any nskb is enqueued.
+ */
+- --cnt;
+- byte_len -= orig_len;
++ qdisc_tree_reduce_backlog(sch, 1 - cnt,
++ orig_len - byte_len);
+ }
+- qdisc_tree_reduce_backlog(sch, -cnt, -byte_len);
+ consume_skb(skb);
+- return err;
++ return cnt > 0 ? NET_XMIT_SUCCESS : err;
+ }
+ return dualpi2_enqueue_skb(skb, sch, to_free);
+ }