locking/lockdep: Disable cross-release features for now

Johan Hovold reported a big lockdep slowdown on his system, caused by lockdep:

> I had noticed that the BeagleBone Black boot time appeared to have
> increased significantly with 4.14 and yesterday I finally had time to
> investigate it.
>
> Boot time (from "Linux version" to login prompt) had in fact doubled
> since 4.13 where it took 17 seconds (with my current config) compared to
> the 35 seconds I now see with 4.14-rc4.
>
> I quick bisect pointed to lockdep and specifically the following commit:
>
>	28a903f63ec0 ("locking/lockdep: Handle non(or multi)-acquisition of a crosslock")

Because the final v4.14 release is close, disable the cross-release lockdep
features for now.

Bisected-by: Johan Hovold <[email protected]>
Debugged-by: Johan Hovold <[email protected]>
Reported-by: Johan Hovold <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Byungchul Park <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2689b7c50c52992623cc8d7e65df03bffc8798d3..e2705843c524d9c6d456c8c17735f870855acb9a 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1092,8 +1092,8 @@ config PROVE_LOCKING
        select DEBUG_MUTEXES
        select DEBUG_RT_MUTEXES if RT_MUTEXES
        select DEBUG_LOCK_ALLOC
-       select LOCKDEP_CROSSRELEASE
-       select LOCKDEP_COMPLETIONS
+       select LOCKDEP_CROSSRELEASE if BROKEN
+       select LOCKDEP_COMPLETIONS if BROKEN
        select TRACE_IRQFLAGS
        default n
        help