Re: INFO: rcu detected stall in sys_sendfile64 (2)

[Tetsuo Handa]

On 2019/03/13 2:15, Dmitry Vyukov wrote:
>> Also, this bisection is finding multiple different crash patterns, which
>> suggests that the crashed tests are not giving correct feedback to syzbot.
> 
> Treating different crashes as just "crash" is intended. Kernel bugs
> can manifest in very different ways.
> Want fun, search for "bpf: sockhash, disallow bpf_tcp_close and update
> in parallel" in  https://syzkaller.appspot.com/?fixed=upstream
> It lead to 50+ different failure modes.
> 

But syzbot already found a rather simple C reproducer
( https://syzkaller.appspot.com/text?tag=ReproC&x=116fc7a8c00000 ) for this bug.
Was this reproducer used for bisection? I guess that if this reproducer was used,
syzbot did not hit "WARNING: ODEBUG bug in netdev_freemem" cases.

Also, humans can sometimes find more simpler C reproducers from syzbot provided
reproducers. It would be nice if syzbot can accept and use a user defined C
reproducer for testing.