On Mon, Oct 30 2006, Arjan van de Ven wrote: > > > > > > > > > > [<c0219091>] cfq_set_request+0x351/0x3b0 > > > [<c020c7fc>] elv_set_request+0x1c/0x40 > > > [<c020fcff>] get_request+0x23f/0x270 > > > [<c0210537>] get_request_wait+0x27/0x120 > > > [<c02107ca>] __make_request+0x5a/0x350 > > > [<c020f40f>] generic_make_request+0x16f/0x220 > > > [<c02117e4>] submit_bio+0x64/0x110 > > > > > > now cfq_set_request() uses several inlines which muddies the situation, > > > but lockdep claims one of them is not done correctly. (eg either it > > > takes the lock incorrectly or something does spin_unlock_irq while the > > > lock is held) > > > > It's not really inlined trickery, the trace is exactly as printed. > > what I meant is that cfq_set_request() calls a few inlines that also > take locks so it might be one of those instead I looked over them, and cfq_cic_link() should use _irqsave() instead of _irq() if called without __GFP_WAIT set. That doesn't happen in the normal io path though, so I'm not sure that is it. So if the bug is using spin_lock_irq() with interrupts already disabled, iirc that would trigger a different warning... > > A few > > things may be allocated from that path, so we pass gfp_mask around. I'll > > double check it tonight, but I don't currently see what could be wrong. > > Would lockdep complain about: > > > > spin_lock_irqsave(lock, flags); > > ... > > spin_unlock_irq(lock); > > ... > > spin_lock_irq(lock); > > ... > > spin_unlock_irqrestore(lock, flags); > > this is fine for lockdep IF and only IF there is no "out lock" held > around this that requires irqs to be off. So if you do > > spin_lock_irqsave(lock1, flags); > ... > spin_lock_irqsave(lock2, flags); > spin_unlock_irq(lock2) > ... > > then lockdep WILL complain, and rightfully so, about a violation since > lock1 gets violated here ;) Naturally, that is a bug fair and simple, nothing to do with lockdep. diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 4bae64e..da9bddf 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1355,6 +1355,7 @@ cfq_cic_link(struct cfq_data *cfqd, stru struct rb_node **p; struct rb_node *parent; struct cfq_io_context *__cic; + unsigned long flags; void *k; cic->ioc = ioc; @@ -1384,9 +1385,9 @@ restart: rb_link_node(&cic->rb_node, parent, p); rb_insert_color(&cic->rb_node, &ioc->cic_root); - spin_lock_irq(cfqd->queue->queue_lock); + spin_lock_irqsave(cfqd->queue->queue_lock, flags); list_add(&cic->queue_list, &cfqd->cic_list); - spin_unlock_irq(cfqd->queue->queue_lock); + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); } /* -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
