netdev - Re: Repeatable inet6_dump_fib crash in stock 4.12.0-rc4+

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Message-ID: <09a00004-da54-dc8f-5806-9576bbf577c7@candelatech.com>
Date:   Tue, 20 Jun 2017 07:12:27 -0700
From:   Ben Greear <greearb@...delatech.com>
To:     David Ahern <dsahern@...il.com>,
        Cong Wang <xiyou.wangcong@...il.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: Repeatable inet6_dump_fib crash in stock 4.12.0-rc4+



On 06/14/2017 03:25 PM, David Ahern wrote:
> On 6/14/17 4:23 PM, Ben Greear wrote:
>> On 06/13/2017 07:27 PM, David Ahern wrote:
>>
>>> Let's try a targeted debug patch. See attached
>>
>> I had to change it to pr_err so it would go to our serial console
>> since the system locked hard on crash,
>> and that appears to be enough to change the timing where we can no longer
>> reproduce the problem.
>
>
> ok, let's figure out which one is doing that. There are 3 debug
> statements. I suspect fib6_del_route is the one setting the state to
> FWS_U. Can you remove the debug prints in fib6_repair_tree and
> fib6_walk_continue and try again?

We cannot reproduce with just that one printf in the kernel either.  It
must change the timing too much to trigger the bug.

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com