On 8/3/21 7:02 AM, Jens Axboe wrote: > On 8/3/21 1:06 AM, Ming Lei wrote: >> blkcg->lock depends on q->queue_lock which may depend on another driver >> lock required in irq context, one example is dm-thin: >> >> Chain exists of: >> &pool->lock#3 --> &q->queue_lock --> &blkcg->lock >> >> Possible interrupt unsafe locking scenario: >> >> CPU0 CPU1 >> ---- ---- >> lock(&blkcg->lock); >> local_irq_disable(); >> lock(&pool->lock#3); >> lock(&q->queue_lock); >> <Interrupt> >> lock(&pool->lock#3); >> >> Fix the issue by using spin_lock_irq(&blkcg->lock) in ioc_weight_write(). > > This looks fine to me for blk-iocost, but block/blk-cgroup.c:blkg_create() > also looks like it gets the IRQ state of the same lock wrong? Ah, that one is under the queue lock, so irqs are already disabled. -- Jens Axboe
