Re: lockdep trace from posix timers

[Oleg Nesterov]

On 08/20, Peter Zijlstra wrote:
>
> On Mon, 2012-08-20 at 17:32 +0200, Oleg Nesterov wrote:
>
> > > I guess we could steal the entire list and requeue it afterwards and
> > > lift TIF_NOTIFY_RESUME along with it..
> >
> > We can't. This can race with exit_task_work(). And this can break
> > fput(), the task can return to the userspace without __fput().
>
> So we could put that spinlock back around cancel and run and leave add
> lockless. That'd solve my immediate problem but its not something I'm
> proud of.

Which problem?

We can probably use bit_spin_lock() and avoid ->pi_lock.

Of course, we can add the new lock into task_struct, but this is not nice.

Oleg.

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