netdev - Re: INFO: rcu detected stall in corrupted

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Date:   Thu, 24 May 2018 17:02:59 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        David Miller <davem@...emloft.net>,
        syzbot+f116bc1994efe725d51b@...kaller.appspotmail.com,
        kuznet <kuznet@....inr.ac.ru>,
        LKML <linux-kernel@...r.kernel.org>,
        network dev <netdev@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        yoshfuji <yoshfuji@...ux-ipv6.org>, dsahern@...nel.org,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        linux-sctp@...r.kernel.org
Subject: Re: INFO: rcu detected stall in corrupted

On Thu, May 24, 2018 at 7:13 AM, Marcelo Ricardo Leitner
<marcelo.leitner@...il.com> wrote:
> On Mon, May 21, 2018 at 11:13:46AM -0700, Eric Dumazet wrote:
>>
>>
>> On 05/21/2018 11:09 AM, David Miller wrote:
>> > From: syzbot <syzbot+f116bc1994efe725d51b@...kaller.appspotmail.com>
>> > Date: Mon, 21 May 2018 11:05:02 -0700
>> >
>> >>  find_match+0x244/0x13a0 net/ipv6/route.c:691
>> >>  find_rr_leaf net/ipv6/route.c:729 [inline]
>> >>  rt6_select net/ipv6/route.c:779 [inline]
>> >
>> > Hmmm, endless loop in find_rr_leaf or similar?
>> >
>>
>>
>> I do not think so, this really looks like SCTP specific
>> , we now have dozens of traces all sharing :
>>
>>  sctp_transport_route+0xad/0x450 net/sctp/transport.c:293
>>  sctp_packet_config+0xb89/0xfd0 net/sctp/output.c:123
>>  sctp_outq_flush+0x79c/0x4370 net/sctp/outqueue.c:894
>>  sctp_outq_uncork+0x6a/0x80 net/sctp/outqueue.c:776
>>  sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1820 [inline]
>>  sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
>>  sctp_do_sm+0x596/0x7160 net/sctp/sm_sideeffect.c:1191
>>  sctp_generate_heartbeat_event+0x218/0x450 net/sctp/sm_sideeffect.c:406
>>  call_timer_fn+0x230/0x940 kernel/time/timer.c:1326
>>
>>
>> Some kind of infinite loop.
>>
>> When the hrtimer fires, it can point to any code that sits below but does not necessarily have a bug.
>
> Agreed. Xin Long identified the root cause. syzkaller is setting too
> aggressive parameters to SCTP RTO, leading to issues with the
> heartbeat timer.
Right, I will prepare a fix soon with your suggestion rto_min value "HZ/5"
Thanks.