[tip:locking/urgent] locking/ww_mutex: Adjust the lock number for stress test

[tip-bot for Boqun Feng]

Commit-ID:  857811a37129f5d2ba162d7be3986eff44724014
Gitweb:     http://git.kernel.org/tip/857811a37129f5d2ba162d7be3986eff44724014
Author:     Boqun Feng <boqun.feng@xxxxxxxxx>
AuthorDate: Wed, 1 Mar 2017 23:01:38 +0800
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 2 Mar 2017 09:00:39 +0100

locking/ww_mutex: Adjust the lock number for stress test

Because there are only 12 bits in held_lock::references, so we only
support 4095 nested lock held in the same time, adjust the lock number
for ww_mutex stress test to kill one lockdep splat:

  [ ] [ BUG: bad unlock balance detected! ]
  [ ] kworker/u2:0/5 is trying to release lock (ww_class_mutex) at:
  [ ] ww_mutex_unlock()
  [ ] but there are no more locks to release!
  ...

Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Nicolai HÃhnle <Nicolai.Haehnle@xxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170301150138.hdixnmafzfsox7nn@xxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/locking/test-ww_mutex.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index 3eb39c5..6b7abb3 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -627,7 +627,7 @@ static int __init test_ww_mutex_init(void)
 	if (ret)
 		return ret;
 
-	ret = stress(4096, hweight32(STRESS_ALL)*ncpus, 1<<12, STRESS_ALL);
+	ret = stress(4095, hweight32(STRESS_ALL)*ncpus, 1<<12, STRESS_ALL);
 	if (ret)
 		return ret;