From: Dmitry Vyukov <dvyukov@google.com>
To: Eric Dumazet <edumazet@google.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
David Miller <davem@davemloft.net>,
Cong Wang <xiyou.wangcong@gmail.com>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
James Morris <jmorris@namei.org>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Patrick McHardy <kaber@trash.net>,
netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: net: deadlock between ip_expire/sch_direct_xmit
Date: Tue, 14 Mar 2017 15:58:31 +0100 [thread overview]
Message-ID: <CACT4Y+bEk8TFZDcuH9S6AJ0A8uJs7ptS3ELHe-DcxkEE3Oanhg@mail.gmail.com> (raw)
In-Reply-To: <CANn89iLO1neA3-4ipYr==n_3iDXDXgY0MCkPkp=cEf8n4w6i=g@mail.gmail.com>
On Tue, Mar 14, 2017 at 3:56 PM, Eric Dumazet <edumazet@google.com> wrote:
> On Tue, Mar 14, 2017 at 7:46 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
>
>> I am confused. Lockdep has observed both of these stacks:
>>
>> CPU0 CPU1
>> ---- ----
>> lock(&(&q->lock)->rlock);
>> lock(_xmit_ETHER#2);
>> lock(&(&q->lock)->rlock);
>> lock(_xmit_ETHER#2);
>>
>>
>> So it somehow happened. Or what do you mean?
>>
>
> Lockdep said " possible circular locking dependency detected " .
> It is not an actual deadlock, but lockdep machinery firing.
>
> For a dead lock to happen, this would require that he ICMP message
> sent by ip_expire() is itself fragmented and reassembled.
> This cannot be, because ICMP messages are not candidates for
> fragmentation, but lockdep can not know that of course...
Ah, I see. Thanks.
next prev parent reply other threads:[~2017-03-14 14:58 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-14 13:31 net: deadlock between ip_expire/sch_direct_xmit Dmitry Vyukov
2017-03-14 14:41 ` Eric Dumazet
2017-03-14 14:46 ` Dmitry Vyukov
2017-03-14 14:56 ` Eric Dumazet
2017-03-14 14:58 ` Dmitry Vyukov [this message]
2017-03-14 16:41 ` Cong Wang
2017-03-20 9:59 ` Dmitry Vyukov
2017-03-20 12:43 ` Eric Dumazet
2017-03-14 15:03 ` Paolo Abeni
2017-03-14 15:09 ` Eric Dumazet
2017-03-14 15:34 ` Paolo Abeni
2017-03-22 15:57 ` [PATCH net] inet: frag: release spinlock before calling icmp_send() Eric Dumazet
2017-03-22 22:41 ` David Miller
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