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

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (24/10/16 21:35), Ming Lei wrote:
> 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);

blk_enter_queue()->schedule() holds ->open_mutex, so that block
of code sleeps on ->open_mutex. We can't drain under ->open_mutex.