Re: Blockdev 6.13-rc lockdep splat regressions

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

On Sun, Jan 12, 2025 at 12:33:13PM +0100, Thomas Hellström wrote:
> On Sat, 2025-01-11 at 11:05 +0800, Ming Lei wrote:
> > On Fri, Jan 10, 2025 at 03:36:44PM +0100, Thomas Hellström wrote:
> > > On Fri, 2025-01-10 at 20:13 +0800, Ming Lei wrote:
> > > > On Fri, Jan 10, 2025 at 11:12:58AM +0100, Thomas Hellström wrote:
> > > > > Ming, Others
> > > > > 
> 
> #2:
> [    5.595482] ======================================================
> [    5.596353] WARNING: possible circular locking dependency detected
> [    5.597231] 6.13.0-rc6+ #122 Tainted: G     U            
> [    5.598182] ------------------------------------------------------
> [    5.599149] (udev-worker)/867 is trying to acquire lock:
> [    5.600075] ffff9211c02f7948 (&root->kernfs_rwsem){++++}-{4:4}, at:
> kernfs_remove+0x31/0x50
> [    5.600987] 
>                but task is already holding lock:
> [    5.603025] ffff9211e86f41a0 (&q->q_usage_counter(io)#3){++++}-
> {0:0}, at: blk_mq_freeze_queue+0x12/0x20
> [    5.603033] 
>                which lock already depends on the new lock.
> 
> [    5.603034] 
>                the existing dependency chain (in reverse order) is:
> [    5.603035] 
>                -> #2 (&q->q_usage_counter(io)#3){++++}-{0:0}:
> [    5.603038]        blk_alloc_queue+0x319/0x350
> [    5.603041]        blk_mq_alloc_queue+0x63/0xd0

The above one is solved in for-6.14/block of block tree:

	block: track queue dying state automatically for modeling queue freeze lockdep

q->q_usage_counter(io) is killed because disk isn't up yet.

If you apply the noio patch against for-6.1/block, the two splats should
have disappeared. If not, please post lockdep log.

Thanks,
Ming