On Fri, May 16, 2014 at 11:32 PM, Jens Axboe <ax...@kernel.dk> wrote: > On 2014-05-16 09:31, Ming Lei wrote: >> >> When there isn't enough vring descriptor for adding to vq, >> blk-mq will be put as stopped state until some of pending >> descriptors are completed & freed. >> >> Unfortunately, the vq's interrupt may come just before >> blk-mq's BLK_MQ_S_STOPPED flag is set, so the blk-mq will >> still be kept as stopped even though lots of descriptors >> are completed and freed in the interrupt handler. The worst >> case is that all pending descriptors are freed in the >> interrupt handler, and the queue is kept as stopped forever. >> >> This patch fixes the problem by starting/stopping blk-mq >> with holding vq_lock. > > > Thanks, this looks good, I'll apply it for 3.16 (with a stable marker, even > if it is an unlikely event).
Thanks. It shouldn't be very difficult to happen in case of non-indirect descriptor, and it is easy to reproduce when module parameter of 'virtblk_queue_depth' is bigger than vq->num_free for non-indirect case. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
