Messages in this thread | | | Date | Fri, 17 Aug 2012 17:17:47 +0200 | From | Oleg Nesterov <> | Subject | Re: lockdep trace from posix timers |
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On 08/17, Oleg Nesterov wrote: > > On 08/16, Peter Zijlstra wrote: > > > > write_lock_irq(&tasklist_lock) > > task_lock(parent) parent->alloc_lock > > And this is already wrong. See the comment above task_lock(). > > > And since it_lock is IRQ-safe and alloc_lock isn't, you've got the IRQ > > inversion deadlock reported. > > Yes. Or, IOW, write_lock(tasklist) is IRQ-safe and thus it can't nest > with alloc_lock. > > > David, Al, anybody want to have a go at fixing this? > > I still think that task_work_add() should synhronize with exit_task_work() > itself and fail if necessary. But I wasn't able to convince Al ;)
And this is my old patch: http://marc.info/?l=linux-kernel&m=134082268721700 It should be re-diffed of course.
Oleg.
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