Re: [PATCH 1/2] block: also mark disk-owned queues as dying in __blk_mark_disk_dead

[Ming Lei <ming.lei@redhat.com>]

On Wed, Oct 09, 2024 at 01:38:20PM +0200, Christoph Hellwig wrote:
> When del_gendisk shuts down access to a gendisk, it could lead to a
> deadlock with sd or, which try to submit passthrough SCSI commands from
> their ->release method under open_mutex.  The submission can be blocked
> in blk_enter_queue while del_gendisk can't get to actually telling them
> top stop and wake them up.

When ->release() waits in blk_enter_queue(), the following code block

	mutex_lock(&disk->open_mutex);
	__blk_mark_disk_dead(disk);
	xa_for_each_start(&disk->part_tbl, idx, part, 1)
	        drop_partition(part);
	mutex_unlock(&disk->open_mutex);

in del_gendisk() should have been done.

Then del_gendisk() should move on and finally unfreeze queue, so I still
don't get the idea how the above dead lock is triggered.


Thanks,
Ming