| Message ID | 1446613120.4184.9.camel@edumazet-glaptop2.roam.corp.google.com |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On 2015-11-04 06:58, Eric Dumazet wrote: > On Tue, 2015-11-03 at 20:46 -0800, Eric Dumazet wrote: >> 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@nuclearcat.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. > > Following patch would be more appropriate. > Prior one was meant to 'show' the issue. > > diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c > index cb5d4ad32946..7f5f3e8a10f5 100644 > --- a/net/sched/sch_generic.c > +++ b/net/sched/sch_generic.c > @@ -706,9 +706,11 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue > *dev_queue, > spin_lock_bh(root_lock); > > /* Prune old scheduler */ > - if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1) > - qdisc_reset(oqdisc); > - > + if (oqdisc) { > + if (atomic_read(&oqdisc->refcnt) <= 1) > + qdisc_reset(oqdisc); > + set_bit(__QDISC_STATE_DEACTIVATED, &oqdisc->state); > + } > /* ... and graft new one */ > if (qdisc == NULL) > qdisc = &noop_qdisc; Applied, will test it, but this bug might be triggered rarely. I will try to push it to more pppoe servers in order to stress test them (and 4.3) more. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index cb5d4ad32946..7f5f3e8a10f5 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -706,9 +706,11 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue, spin_lock_bh(root_lock); /* Prune old scheduler */ - if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1) - qdisc_reset(oqdisc); - + if (oqdisc) { + if (atomic_read(&oqdisc->refcnt) <= 1) + qdisc_reset(oqdisc); + set_bit(__QDISC_STATE_DEACTIVATED, &oqdisc->state); + } /* ... and graft new one */ if (qdisc == NULL) qdisc = &noop_qdisc;