linux-kernel - Re: INFO: rcu detected stall in ndisc_alloc

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Date:   Thu, 3 Jan 2019 02:06:58 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     syzbot <syzbot+ea7d9cb314b4ab49a18a@...kaller.appspotmail.com>,
        David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: INFO: rcu detected stall in ndisc_alloc_skb

On 2018/12/31 17:24, Dmitry Vyukov wrote:
>>> Since this involves OOMs and looks like a one-off induced memory corruption:
>>>
>>> #syz dup: kernel panic: corrupted stack end in wb_workfn
>>>
>>
>> Why?
>>
>> RCU stall in this case is likely to be latency caused by flooding of printk().
> 
> Just a hypothesis. OOMs lead to arbitrary memory corruptions, so can
> cause stalls as well. But can be what you said too. I just thought
> that cleaner dashboard is more useful than a large assorted pile of
> crashes. If you think it's actionable in some way, feel free to undup.
> 

We don't know why bpf tree is hitting this problem.
Let's continue monitoring this problem.

#syz undup