On Wed, Jun 16, 2021 at 10:30:23AM +0800, Ming Lei wrote: > Not sure disk is valid, we only hold the disk when opening a bdev, but > the bdev can be closed during polling. How? On a block device the caller needs to hold the block device open to read/write from it. On a file systems the file systems needs to be mounted, which also holds a bdev reference. > Also disk always holds one > reference on request queue, so if disk is valid, no need to grab queue's > refcnt in bio_poll(). But we need to avoid going into the lowlevel blk-mq polling code to not reference the potentially freed hctxs or tags as correctly pointed by yourself on the previous iteration.
