RE: lockdep oddity

Hua Zhong
2006-09-05T18:58:19Z

Maybe we should define raw __likely/__unlikely which behave the same way as the vanilla and use them in places like spinlocks to
avoid these weird problems.

> * Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
>
> > The lock validator gives me this (latest -mm and 2.6.18-rc6):
> >
> > =====================================
> > [ BUG: bad unlock balance detected! ]
> > -------------------------------------
> > swapper/0 is trying to release lock (resource_lock) at:
> > [<0000000000042842>] request_resource+0x52/0x88 but there
> are no more
> > locks to release!
> >
> > The reason is that the BUILD_LOCK_OPS macros in
> kernel/lockdep.c don't
> > contain any of the *_acquire calls, while all of the
> _unlock functions
> > contain a *_release call. Hence I get immediately unbalanced locks.
>
> hmmm ... that sounds like a bug. Weird - i recently ran
> PREEMPT+SMP+LOCKDEP kernels and didnt notice this.
>
> > Found this will debugging some random memory corruptions
> that happen
> > when CONFIG_PROVE_LOCKING and CONFIG_PROFILE_LIKELY are both on.
> > Switching both off or having only one of them on seems to work.
>
> previously i had some weirdnesses with PROFILE_LIKELY too,
> they were caused by it generating cross-calls from within
> lockdep. Do the corruptions go away if you remove all
> likely() and unlikely() markings from kernel/lockdep.c?
>
> Ingo