On Wed, Feb 15, 2017 at 01:01:40AM +0900, Sergey Senozhatsky wrote: > > but I'm a bit confused by rt_b->rt_runtime_lock in this unsafe lock > scenario (so it's not ABBA, but ABAD) > > > lock(hrtimer_bases.lock); > > lock(&rt_b->rt_runtime_lock); > > lock(hrtimer_bases.lock); > > lock(tk_core); > > > > > > Chain exists of: > > > > tk_core --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock > > > I'm lacking some knowledge here, sorry. where does the tk_core --> > &rt_b->rt_runtime_lock > come from?
rt_b->rt_runtime_lock is one of the scheduler locks, since we do printk() under tk_core, which does semaphore muck, which then includes the entire scheduler chain of locks.
