* [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog
@ 2014-10-03 5:43 John Fastabend
2014-10-03 22:22 ` Cong Wang
2014-10-05 0:46 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: John Fastabend @ 2014-10-03 5:43 UTC (permalink / raw)
To: davem; +Cc: xiyou.wangcong, eric.dumazet, netdev
Suspicious RCU usage in qdisc_watchdog call needs to be done inside
rcu_read_lock/rcu_read_unlock. And then Qdisc destroy operations
need to ensure timer is cancelled before removing qdisc structure.
[ 3992.191339] ===============================
[ 3992.191340] [ INFO: suspicious RCU usage. ]
[ 3992.191343] 3.17.0-rc6net-next+ #72 Not tainted
[ 3992.191345] -------------------------------
[ 3992.191347] include/net/sch_generic.h:272 suspicious rcu_dereference_check() usage!
[ 3992.191348]
[ 3992.191348] other info that might help us debug this:
[ 3992.191348]
[ 3992.191351]
[ 3992.191351] rcu_scheduler_active = 1, debug_locks = 1
[ 3992.191353] no locks held by swapper/1/0.
[ 3992.191355]
[ 3992.191355] stack backtrace:
[ 3992.191358] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.17.0-rc6net-next+ #72
[ 3992.191360] Hardware name: /DZ77RE-75K, BIOS GAZ7711H.86A.0060.2012.1115.1750 11/15/2012
[ 3992.191362] 0000000000000001 ffff880235803e48 ffffffff8178f92c 0000000000000000
[ 3992.191366] ffff8802322224a0 ffff880235803e78 ffffffff810c9966 ffff8800a5fe3000
[ 3992.191370] ffff880235803f30 ffff8802359cd768 ffff8802359cd6e0 ffff880235803e98
[ 3992.191374] Call Trace:
[ 3992.191376] <IRQ> [<ffffffff8178f92c>] dump_stack+0x4e/0x68
[ 3992.191387] [<ffffffff810c9966>] lockdep_rcu_suspicious+0xe6/0x130
[ 3992.191392] [<ffffffff8167213a>] qdisc_watchdog+0x8a/0xb0
[ 3992.191396] [<ffffffff810f93f2>] __run_hrtimer+0x72/0x420
[ 3992.191399] [<ffffffff810f9bcd>] ? hrtimer_interrupt+0x7d/0x240
[ 3992.191403] [<ffffffff816720b0>] ? tc_classify+0xc0/0xc0
[ 3992.191406] [<ffffffff810f9c4f>] hrtimer_interrupt+0xff/0x240
[ 3992.191410] [<ffffffff8109e4a5>] ? __atomic_notifier_call_chain+0x5/0x140
[ 3992.191415] [<ffffffff8103577b>] local_apic_timer_interrupt+0x3b/0x60
[ 3992.191419] [<ffffffff8179c2b5>] smp_apic_timer_interrupt+0x45/0x60
[ 3992.191422] [<ffffffff8179a6bf>] apic_timer_interrupt+0x6f/0x80
[ 3992.191424] <EOI> [<ffffffff815ed233>] ? cpuidle_enter_state+0x73/0x2e0
[ 3992.191432] [<ffffffff815ed22e>] ? cpuidle_enter_state+0x6e/0x2e0
[ 3992.191437] [<ffffffff815ed567>] cpuidle_enter+0x17/0x20
[ 3992.191441] [<ffffffff810c0741>] cpu_startup_entry+0x3d1/0x4a0
[ 3992.191445] [<ffffffff81106fc6>] ? clockevents_config_and_register+0x26/0x30
[ 3992.191448] [<ffffffff81033c16>] start_secondary+0x1b6/0x260
Fixes: b26b0d1e8b1 ("net: qdisc: use rcu prefix and silence sparse warnings")
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
---
net/sched/sch_api.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index aa83295..c79a226 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -578,8 +578,10 @@ static enum hrtimer_restart qdisc_watchdog(struct hrtimer *timer)
struct qdisc_watchdog *wd = container_of(timer, struct qdisc_watchdog,
timer);
+ rcu_read_lock();
qdisc_unthrottled(wd->qdisc);
__netif_schedule(qdisc_root(wd->qdisc));
+ rcu_read_unlock();
return HRTIMER_NORESTART;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog
2014-10-03 5:43 [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog John Fastabend
@ 2014-10-03 22:22 ` Cong Wang
2014-10-05 0:46 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Cong Wang @ 2014-10-03 22:22 UTC (permalink / raw)
To: John Fastabend; +Cc: David Miller, Cong Wang, Eric Dumazet, netdev
On Thu, Oct 2, 2014 at 10:43 PM, John Fastabend
<john.fastabend@gmail.com> wrote:
> Suspicious RCU usage in qdisc_watchdog call needs to be done inside
> rcu_read_lock/rcu_read_unlock. And then Qdisc destroy operations
> need to ensure timer is cancelled before removing qdisc structure.
More precisely, qdisc_root().
>
> [ 3992.191339] ===============================
> [ 3992.191340] [ INFO: suspicious RCU usage. ]
> [ 3992.191343] 3.17.0-rc6net-next+ #72 Not tainted
> [ 3992.191345] -------------------------------
> [ 3992.191347] include/net/sch_generic.h:272 suspicious rcu_dereference_check() usage!
> [ 3992.191348]
> [ 3992.191348] other info that might help us debug this:
> [ 3992.191348]
> [ 3992.191351]
> [ 3992.191351] rcu_scheduler_active = 1, debug_locks = 1
> [ 3992.191353] no locks held by swapper/1/0.
> [ 3992.191355]
> [ 3992.191355] stack backtrace:
> [ 3992.191358] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.17.0-rc6net-next+ #72
> [ 3992.191360] Hardware name: /DZ77RE-75K, BIOS GAZ7711H.86A.0060.2012.1115.1750 11/15/2012
> [ 3992.191362] 0000000000000001 ffff880235803e48 ffffffff8178f92c 0000000000000000
> [ 3992.191366] ffff8802322224a0 ffff880235803e78 ffffffff810c9966 ffff8800a5fe3000
> [ 3992.191370] ffff880235803f30 ffff8802359cd768 ffff8802359cd6e0 ffff880235803e98
> [ 3992.191374] Call Trace:
> [ 3992.191376] <IRQ> [<ffffffff8178f92c>] dump_stack+0x4e/0x68
> [ 3992.191387] [<ffffffff810c9966>] lockdep_rcu_suspicious+0xe6/0x130
> [ 3992.191392] [<ffffffff8167213a>] qdisc_watchdog+0x8a/0xb0
> [ 3992.191396] [<ffffffff810f93f2>] __run_hrtimer+0x72/0x420
> [ 3992.191399] [<ffffffff810f9bcd>] ? hrtimer_interrupt+0x7d/0x240
> [ 3992.191403] [<ffffffff816720b0>] ? tc_classify+0xc0/0xc0
> [ 3992.191406] [<ffffffff810f9c4f>] hrtimer_interrupt+0xff/0x240
> [ 3992.191410] [<ffffffff8109e4a5>] ? __atomic_notifier_call_chain+0x5/0x140
> [ 3992.191415] [<ffffffff8103577b>] local_apic_timer_interrupt+0x3b/0x60
> [ 3992.191419] [<ffffffff8179c2b5>] smp_apic_timer_interrupt+0x45/0x60
> [ 3992.191422] [<ffffffff8179a6bf>] apic_timer_interrupt+0x6f/0x80
> [ 3992.191424] <EOI> [<ffffffff815ed233>] ? cpuidle_enter_state+0x73/0x2e0
> [ 3992.191432] [<ffffffff815ed22e>] ? cpuidle_enter_state+0x6e/0x2e0
> [ 3992.191437] [<ffffffff815ed567>] cpuidle_enter+0x17/0x20
> [ 3992.191441] [<ffffffff810c0741>] cpu_startup_entry+0x3d1/0x4a0
> [ 3992.191445] [<ffffffff81106fc6>] ? clockevents_config_and_register+0x26/0x30
> [ 3992.191448] [<ffffffff81033c16>] start_secondary+0x1b6/0x260
>
> Fixes: b26b0d1e8b1 ("net: qdisc: use rcu prefix and silence sparse warnings")
> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Cong Wang <cwang@twopensource.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog
2014-10-03 5:43 [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog John Fastabend
2014-10-03 22:22 ` Cong Wang
@ 2014-10-05 0:46 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2014-10-05 0:46 UTC (permalink / raw)
To: john.fastabend; +Cc: xiyou.wangcong, eric.dumazet, netdev
From: John Fastabend <john.fastabend@gmail.com>
Date: Thu, 02 Oct 2014 22:43:09 -0700
> Suspicious RCU usage in qdisc_watchdog call needs to be done inside
> rcu_read_lock/rcu_read_unlock. And then Qdisc destroy operations
> need to ensure timer is cancelled before removing qdisc structure.
...
> Fixes: b26b0d1e8b1 ("net: qdisc: use rcu prefix and silence sparse warnings")
> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Applied, thank you.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-10-05 0:46 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-10-03 5:43 [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog John Fastabend
2014-10-03 22:22 ` Cong Wang
2014-10-05 0:46 ` David Miller
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.