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Wylie" Cc: Holger =?iso-8859-1?Q?Hoffst=E4tte?= , Jamal Hadi Salim , regressions@lists.linux.dev, Jiri Pirko , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Octavian Purdila , Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= , stable@vger.kernel.org, Greg KH Subject: Re: [REGRESSION] 6.14.3 panic - kernel NULL pointer dereference in htb_dequeue Message-ID: References: <4e2a6522-d455-f0ce-c77d-b430c3047d7c@applied-asynchrony.com> <20250422214716.5e181523@frodo.int.wylie.me.uk> <20250423105131.7ab46a47@frodo.int.wylie.me.uk> <20250424135331.02511131@frodo.int.wylie.me.uk> <20250427204254.6ae5cd4a@frodo.int.wylie.me.uk> <20250427213548.73efc7b9@frodo.int.wylie.me.uk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250427213548.73efc7b9@frodo.int.wylie.me.uk> On Sun, Apr 27, 2025 at 09:35:48PM +0100, Alan J. Wylie wrote: > On Sun, 27 Apr 2025 20:42:54 +0100 > "Alan J. Wylie" wrote: > > > That would be https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/ ? > > > > I've just cloned that. I'll do a build and a test. > > $ uname -r > 6.15.0-rc3-00109-gf73f05c6f711 > > It's crashed. Same place as usual. I tried again, same thing. > > htb_dequeue+0x42e/0x610 [sch_htb] > > Rather than a ping flood, I was running a Speedtest. Both times it > crashed during the upload test, not the download. > > https://www.speedtest.net/ > > Could running an iptables firewall perhaps have anything to do with it? I doubt it is related to iptables. I will try some TCP traffic on my side later, but I suspect this is related to the type of packets. Meanwhile, since I still can't reproduce it here, do you mind applying both of my patches on top of -net and test again? For your convenience, below is the combined patch of the previous two patches, which can be applied on -net. Thanks! -----> diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 4b9a639b642e..9d88fff120bc 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -348,7 +348,8 @@ static void htb_add_to_wait_tree(struct htb_sched *q, */ static inline void htb_next_rb_node(struct rb_node **n) { - *n = rb_next(*n); + if (*n) + *n = rb_next(*n); } /** @@ -1487,7 +1488,8 @@ static void htb_qlen_notify(struct Qdisc *sch, unsigned long arg) if (!cl->prio_activity) return; - htb_deactivate(qdisc_priv(sch), cl); + if (!cl->leaf.q->q.qlen) + htb_deactivate(qdisc_priv(sch), cl); } static inline int htb_parent_last_child(struct htb_class *cl)