Re: [PATCH] panic: lockdep: correct lock debugging state check

[Peter Zijlstra]

On Mon, Apr 25, 2016 at 08:36:37PM -0700, Yang Shi wrote:
> When kernel oops happens, lock debugging is turned off by debug_locks_off()
> in oops_enter() via calling __debug_locks_off() which set debug_locks to 0
> via xchg(). But, calling to __debug_locks_off() to check lock debugging state
> in add_taint() called by oops_end() will always return false since xchg()
> returns the old value of debug_locks which is cleared in oops_enter() already.
> 
> This prevents add_taint() from printing out lock debugging disable information
> although LOCKDEP_NOW_UNRELIABLE is passed to it.
> 
> Check lock debugging state via !debug_locks to fix this. Although
> !__debug_locks_off() could do the same thing, it may look confusing.
> 
What are you smoking? This is the second completely insane patch you
send this week.

This breaks add_taint() and gains us nothing except trivialities. Who
bloody cares about that print if you've just had an OOPS.