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Date: Tue, 03 Nov 2015 20:46:21 -0800 From: Eric Dumazet <eric.dumazet@...il.com> To: Denys Fedoryshchenko <nuclearcat@...learcat.com> Cc: Cong Wang <cwang@...pensource.com>, Jamal Hadi Salim <jhs@...atatu.com>, "David S. Miller" <davem@...emloft.net>, netdev <netdev@...r.kernel.org>, linux-kernel@...r.kernel.org Subject: Re: kernel panic in 4.2.3, rb_erase in sch_fq On Wed, 2015-11-04 at 06:25 +0200, Denys Fedoryshchenko wrote: > On 2015-11-04 00:06, Cong Wang wrote: > > On Mon, Nov 2, 2015 at 6:11 AM, Denys Fedoryshchenko > > <nuclearcat@...learcat.com> wrote: > >> Hi! > >> > >> Actually seems i was getting this panic for a while (once per week) on > >> loaded pppoe server, but just now was able to get full panic message. > >> After checking commit logs on sch_fq.c i didnt seen any fixes, so > >> probably > >> upgrading to newer kernel wont help? > > > > > > Can you share your `tc qdisc show dev xxxx` with us? And how to > > reproduce > > it? I tried to setup htb+fq and then flip the interface back and forth > > but I don't > > see any crash. > My guess it wont be easy to reproduce, it is happening on box with 4.5k > interfaces, that constantly create/delete interfaces, > and even with that this problem may happen once per day, or may not > happen for 1 week. > > Here is script that is being fired after new ppp interface detected. But > pppoe process are independent from > process that are "establishing" shapers. It is probably a generic bug. sch_fq seems OK to me. Somehow nobody tries to change qdisc hundred times per second ;) Could you try following patch ? It seems to 'fix' the issue for me. diff --git a/net/core/dev.c b/net/core/dev.c index 8ce3f74cd6b9..bf136103bc7b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2880,6 +2880,12 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, spin_lock(&q->busylock); spin_lock(root_lock); + if (unlikely(q != rcu_dereference_bh(txq->qdisc))) { + pr_err_ratelimited("Arg, qdisc changed ! state %lx\n", q->state); + kfree_skb(skb); + rc = NET_XMIT_DROP; + goto end; + } if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) { kfree_skb(skb); rc = NET_XMIT_DROP; @@ -2913,6 +2919,7 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, __qdisc_run(q); } } +end: spin_unlock(root_lock); if (unlikely(contended)) spin_unlock(&q->busylock); -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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