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From: "Theodore Ts'o" <tytso@mit.edu>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	syzbot <syzbot+1505c80c74256c6118a5@syzkaller.appspotmail.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: INFO: rcu detected stall in sys_sendfile64 (2)
Date: Wed, 13 Mar 2019 12:37:01 -0400	[thread overview]
Message-ID: <20190313163701.GE672@mit.edu> (raw)
In-Reply-To: <CACT4Y+ZQD=raWY4Tp8nrUcpAAbwRt0D3sH65KrTP+JURtQ3n-Q@mail.gmail.com>

On Wed, Mar 13, 2019 at 07:43:38AM +0100, Dmitry Vyukov wrote:
> It would be more useful to accept patches that make syzkaller create
> better reproducers from these people. Manual work is not scalable. We
> would need 10 reproducers per day for a dozen of OSes (incl some
> private kernels/branches). Anybody is free to run syzkaller manually
> and do full manual (perfect) reporting. But for us it become clear
> very early that it won't work. Then see above, while that human is
> sleeping/on weekend/vacation, syzbot will already bisect own
> reproducer. Adding manual reproducer later won't help in any way.
> syzkaller already does lots of smart work for reproducers. Let's not
> give up on the last mile and switch back to all manual work.

I suspect a scalable solution that would significantly improve things
is one where Syzbot tries N times for a "good" result to make sure
it's not a flaky pass.  N could either be hard-coded to some value
like 8 or 10, or Syzbot could experimentally try to figure out how
reliable the reproducer happens to be, and figure out what an ideal
"N" value should be for a particular reproducer.

					- Ted

  reply	other threads:[~2019-03-13 16:37 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-19 11:32 INFO: rcu detected stall in sys_sendfile64 (2) syzbot
2019-01-19 11:41 ` Dmitry Vyukov
2019-01-19 13:00   ` Tetsuo Handa
2019-03-12  3:59 ` syzbot
2019-03-12  4:08   ` Al Viro
2019-03-12  8:00     ` Jani Nikula
2019-03-12 14:29     ` Tetsuo Handa
2019-03-12 17:15       ` Dmitry Vyukov
2019-03-12 21:11         ` Tetsuo Handa
2019-03-13  6:43           ` Dmitry Vyukov
2019-03-13 16:37             ` Theodore Ts'o [this message]
2019-03-13 16:56               ` Dmitry Vyukov
2019-03-13 23:40             ` Eric Biggers
2019-03-14 10:52               ` Tetsuo Handa
2019-03-20 12:49                 ` Dmitry Vyukov
2019-03-20 13:45                 ` Dmitry Vyukov
2019-03-12 17:10     ` Dmitry Vyukov

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