[PATCH] locking/lockdep: Save and display stack trace of held locks

[Peter Zijlstra]

On Mon, Jun 24, 2019 at 04:00:59PM +0800, Kobe Wu wrote:
> Save the stack trace of held locks when lock_acquire() is invoked
> and display the stack trace when lockdep_print_held_locks() is
> invoked. The runtime stack trace of held locks are helpful in
> analyzing code flow and lockdep's warning.
> 
> Save stack trace of each held lock will increase runtime overhead
> and memory consumption. The operation will be activated under
> CONFIG_LOCKDEP_TRACE_HELD_LOCK. So the impact will only occur
> when CONFIG_LOCKDEP_TRACE_HELD_LOCK=y.

Yeah, I don't see the point of this. If you cannot find where the lock
got taken you've bigger problems.