On Fri, 2010-07-09 at 00:19 -0700, Darren Hart wrote: > Walking through it: > > First the dumps: > ------------[ cut here ]------------ > WARNING: at kernel/rtmutex.c:583 wakeup_next_waiter+0x1ad/0x220() > > > WARN_ON(pendowner->pi_blocked_on != waiter); > The pi_blocked_on is not NULL, but it isn't the expected waiter either. > This means that the top waiter selected at the beginning of > wakeup_next_waiter() is now blocked on a lock with a different waiter > structure, possibly on a different lock. pendowner->pi_blocked_on changes while we're in wakeup_next_waiter(). The below fi^Wmade it not do that any more. We hold the wait_lock for this lock, but if the wakee blocks on another, what's protecting us? bandaid-by: /me diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index 23dd443..dd91ede 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -525,6 +525,8 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int savestate) pendowner = waiter->task; waiter->task = NULL; + raw_spin_lock(&pendowner->pi_lock); + /* * Do the wakeup before the ownership change to give any spinning * waiter grantees a headstart over the other threads that will @@ -577,8 +579,6 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int savestate) else next = NULL; - raw_spin_lock(&pendowner->pi_lock); - WARN_ON(!pendowner->pi_blocked_on); WARN_ON(pendowner->pi_blocked_on != waiter); WARN_ON(pendowner->pi_blocked_on->lock != lock); -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
