On RT struct plist_head->lock is a raw_spinlock_t, but struct futex_hash_bucket->lock, that is set to plist_head->lock is a spinlock, which becomes a mutex on RT. Later in plist_check_head spin_is_locked can't figure out what is the right type, triggering a WARN_ON_SMP. As we were already special casing PREEMPT_RT on plist_check_head.. Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> diff -uNrp linux-2.6.23-rt1.orig/kernel/futex.c linux-2.6.23-rt1/kernel/futex.c --- linux-2.6.23-rt1.orig/kernel/futex.c 2007-10-22 12:28:11.000000000 -0200 +++ linux-2.6.23-rt1/kernel/futex.c 2007-10-22 12:27:07.000000000 -0200 @@ -947,9 +947,13 @@ static int futex_requeue(u32 __user *uad plist_del(&this->list, &hb1->chain); plist_add(&this->list, &hb2->chain); this->lock_ptr = &hb2->lock; -#if defined(CONFIG_DEBUG_PI_LIST) && !defined(CONFIG_PREEMPT_RT) +#ifdef CONFIG_DEBUG_PI_LIST +#ifdef CONFIG_PREEMPT_RT + this->list.plist.lock = NULL; +#else this->list.plist.lock = &hb2->lock; #endif +#endif } this->key = key2; get_futex_key_refs(&key2); @@ -1008,9 +1012,13 @@ static inline void __queue_me(struct fut prio = min(current->normal_prio, MAX_RT_PRIO); plist_node_init(&q->list, prio); -#if defined(CONFIG_DEBUG_PI_LIST) && !defined(CONFIG_PREEMPT_RT) +#ifdef CONFIG_DEBUG_PI_LIST +#ifdef CONFIG_PREEMPT_RT + q->list.plist.lock = NULL; +#else q->list.plist.lock = &hb->lock; #endif +#endif plist_add(&q->list, &hb->chain); q->task = current; spin_unlock(&hb->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
