From: John Fastabend <john.fastabend@gmail.com>
To: davem@davemloft.net
Cc: xiyou.wangcong@gmail.com, eric.dumazet@gmail.com, netdev@vger.kernel.org
Subject: [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog
Date: Thu, 02 Oct 2014 22:43:09 -0700 [thread overview]
Message-ID: <20141003054306.20821.48420.stgit@nitbit.x32> (raw)
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;
}
next reply other threads:[~2014-10-03 5:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 5:43 John Fastabend [this message]
2014-10-03 22:22 ` [PATCH] net: sched: suspicious RCU usage in qdisc_watchdog Cong Wang
2014-10-05 0:46 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141003054306.20821.48420.stgit@nitbit.x32 \
--to=john.fastabend@gmail.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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.