On Mon, Sep 18, 2017 at 09:55:27AM -0700, Paul E. McKenney wrote: > On Mon, Sep 18, 2017 at 12:29:31PM -0400, Steven Rostedt wrote: > > On Mon, 18 Sep 2017 09:24:12 -0700 > > "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote: > > > > > > > As soon as I work through the backlog of lockdep complaints that > > > appeared in the last merge window... :-( > > > > > > sparse_irq_lock, I am looking at you!!! ;-)
That one is a false positive and I have send patches to address. > > I just hit one too, and decided to write a patch to show a chain of 3 > > when applicable. > > > > For example: > > > > Chain exists of: > > cpu_hotplug_lock.rw_sem --> smpboot_threads_lock --> > > (complete)&self->parked > > > > Possible unsafe locking scenario by crosslock: > > > > CPU0 CPU1 CPU2 > > ---- ---- ---- > > lock(smpboot_threads_lock); > > lock((complete)&self->parked); > > lock(cpu_hotplug_lock.rw_sem); > > lock(smpboot_threads_lock); > > > > lock(cpu_hotplug_lock.rw_sem); > > > > unlock((complete)&self->parked); > > > > *** DEADLOCK *** > > > > :-) > > Nice!!! That one looks like the watchdog thing, and Thomas was poking at that.
