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!!! ;-)
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 ***
:-)
-- Steve
