From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: "Jens Axboe" <axboe@kernel.dk>,
linux-block@vger.kernel.org, "Nilay Shroff" <nilay@linux.ibm.com>,
"Shinichiro Kawasaki" <shinichiro.kawasaki@wdc.com>,
"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
"Christoph Hellwig" <hch@lst.de>
Subject: Re: [PATCH V3 17/20] block: move debugfs/sysfs register out of freezing queue
Date: Fri, 25 Apr 2025 20:38:01 +0200 [thread overview]
Message-ID: <20250425183801.GC26393@lst.de> (raw)
In-Reply-To: <20250424152148.1066220-18-ming.lei@redhat.com>
On Thu, Apr 24, 2025 at 11:21:40PM +0800, Ming Lei wrote:
> Move debugfs/sysfs register out of freezing queue in
> __blk_mq_update_nr_hw_queues(), so that the following lockdep dependency
> can be killed:
>
> #2 (&q->q_usage_counter(io)#16){++++}-{0:0}:
> #1 (fs_reclaim){+.+.}-{0:0}:
> #0 (&sb->s_type->i_mutex_key#3){+.+.}-{4:4}: //debugfs
>
> And registering/un-registering debugfs/sysfs does not require queue to be
> frozen.
Please explain the why it's not required. And talking about lockdep
dependencies is not very useful - it either is an actual lock ordering
issue or a fale positive, but lockdep is just the messenger.
next prev parent reply other threads:[~2025-04-25 18:38 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-24 15:21 [PATCH V3 00/20] block: unify elevator changing and fix lockdep warning Ming Lei
2025-04-24 15:21 ` [PATCH V3 01/20] block: move blk_mq_add_queue_tag_set() after blk_mq_map_swqueue() Ming Lei
2025-04-24 15:21 ` [PATCH V3 02/20] block: move ELEVATOR_FLAG_DISABLE_WBT a request queue flag Ming Lei
2025-04-25 14:29 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 03/20] block: don't call freeze queue in elevator_switch() and elevator_disable() Ming Lei
2025-04-25 14:29 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 04/20] block: use q->elevator with ->elevator_lock held in elv_iosched_show() Ming Lei
2025-04-25 6:08 ` Hannes Reinecke
2025-04-25 10:53 ` Nilay Shroff
2025-04-25 14:29 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 05/20] block: add two helpers for registering/un-registering sched debugfs Ming Lei
2025-04-24 15:21 ` [PATCH V3 06/20] block: move sched debugfs register into elvevator_register_queue Ming Lei
2025-04-24 15:21 ` [PATCH V3 07/20] block: prevent adding/deleting disk during updating nr_hw_queues Ming Lei
2025-04-25 6:33 ` Hannes Reinecke
2025-04-25 11:37 ` Nilay Shroff
2025-04-25 14:33 ` Christoph Hellwig
2025-04-25 16:46 ` kernel test robot
2025-04-24 15:21 ` [PATCH V3 08/20] block: don't allow to switch elevator if updating nr_hw_queues is in-progress Ming Lei
2025-04-25 6:33 ` Hannes Reinecke
2025-04-25 12:48 ` Nilay Shroff
2025-04-27 2:27 ` Ming Lei
2025-04-28 16:17 ` Nilay Shroff
2025-04-29 2:43 ` Ming Lei
2025-04-29 10:22 ` Nilay Shroff
2025-04-30 0:54 ` Ming Lei
2025-04-24 15:21 ` [PATCH V3 09/20] block: simplify elevator reattachment for updating nr_hw_queues Ming Lei
2025-04-25 6:34 ` Hannes Reinecke
2025-04-25 18:12 ` Christoph Hellwig
2025-04-29 9:51 ` Ming Lei
2025-04-24 15:21 ` [PATCH V3 10/20] block: move blk_unregister_queue() & device_del() after freeze wait Ming Lei
2025-04-25 6:35 ` Hannes Reinecke
2025-04-25 12:50 ` Nilay Shroff
2025-04-25 14:34 ` Christoph Hellwig
2025-04-28 11:51 ` Ming Lei
2025-04-24 15:21 ` [PATCH V3 11/20] block: move queue freezing & elevator_lock into elevator_change() Ming Lei
2025-04-25 6:36 ` Hannes Reinecke
2025-04-25 12:54 ` Nilay Shroff
2025-04-25 14:35 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 12/20] block: add `struct elv_change_ctx` for unifying elevator change Ming Lei
2025-04-25 6:38 ` Hannes Reinecke
2025-04-25 18:23 ` Christoph Hellwig
2025-04-29 15:45 ` Ming Lei
2025-04-24 15:21 ` [PATCH V3 13/20] block: " Ming Lei
2025-04-25 6:39 ` Hannes Reinecke
2025-04-25 13:03 ` Nilay Shroff
2025-04-30 0:46 ` Ming Lei
2025-04-25 18:30 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 14/20] block: pass elevator_queue to elv_register_queue & unregister_queue Ming Lei
2025-04-25 6:40 ` Hannes Reinecke
2025-04-24 15:21 ` [PATCH V3 15/20] block: fail to show/store elevator sysfs attribute if elevator is dying Ming Lei
2025-04-25 6:45 ` Hannes Reinecke
2025-04-25 18:36 ` Christoph Hellwig
2025-04-30 1:07 ` Ming Lei
2025-04-24 15:21 ` [PATCH V3 16/20] block: move elv_register[unregister]_queue out of elevator_lock Ming Lei
2025-04-25 6:46 ` Hannes Reinecke
2025-04-25 13:05 ` Nilay Shroff
2025-04-25 18:37 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 17/20] block: move debugfs/sysfs register out of freezing queue Ming Lei
2025-04-25 6:47 ` Hannes Reinecke
2025-04-25 18:38 ` Christoph Hellwig [this message]
2025-04-28 11:28 ` Ming Lei
2025-04-24 15:21 ` [PATCH V3 18/20] block: remove several ->elevator_lock Ming Lei
2025-04-25 6:48 ` Hannes Reinecke
2025-04-25 18:38 ` Christoph Hellwig
2025-04-24 15:21 ` [PATCH V3 19/20] block: move hctx cpuhp add/del out of queue freezing Ming Lei
2025-04-25 6:49 ` Hannes Reinecke
2025-04-24 15:21 ` [PATCH V3 20/20] block: move wbt_enable_default() out of queue freezing from sched ->exit() Ming Lei
2025-04-25 13:10 ` Nilay Shroff
2025-04-29 10:59 ` Nilay Shroff
2025-04-29 12:00 ` [PATCH V3 00/20] block: unify elevator changing and fix lockdep warning Stefan Haberland
2025-04-29 12:11 ` Ming Lei
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