Re: [writeback] 8bc4ad9498: INFO: suspicious RCU usage. ]

From: Tejun Heo
Date: Fri Sep 02 2016 - 14:00:59 EST


Hello, Paul.

On Fri, Sep 02, 2016 at 10:00:56AM -0700, Paul E. McKenney wrote:
> Note that lockdep believes that the rcu_read_lock() has also been
> dropped, otherwise it would have listed it.

There isn't any actual code between rcu_read_lock() and the following
rcu deref. That's the first thing which happens. It looked
mysterious to me so I was wondering whether you knew any brekages on
rcu lockdep side. Unfortunately, that doesn't seem to be the case.

> At this point, I have to suggest "git bisect"...

I'll try to reproduce it and see wth is going on.

Thanks!

--
tejun