On Thu, 2025-10-30 at 10:24 -0700, Bart Van Assche wrote:
Freezing the request queue from inside sysfs store callbacks may cause a deadlock in combination with the dm-multipath driver and the queue_if_no_path option. Additionally, freezing the request queue slows down system boot on systems where sysfs attributes are set synchronously.
Fix this by removing the blk_mq_freeze_queue() / blk_mq_unfreeze_queue() calls from the store callbacks that do not strictly need these callbacks. This patch may cause a small delay in applying the new settings.
This patch affects the following sysfs attributes:
- io_poll_delay
- io_timeout
- nomerges
- read_ahead_kb
- rq_affinity
...
Cc: Christoph Hellwig hch@lst.de Cc: Nilay Shroff nilay@linux.ibm.com Cc: Martin Wilck mwilck@suse.com Cc: Benjamin Marzinski bmarzins@redhat.com Cc: stable@vger.kernel.org Fixes: af2814149883 ("block: freeze the queue in queue_attr_store") Signed-off-by: Bart Van Assche bvanassche@acm.org
Changes compared to v2: - Dropped the controversial patch "block: Restrict the duration of sysfs attribute changes".
So the "deadlock" situation for the other sysfs attributes that you handled with the timeout in v2 will remain now? Are you planning to send a follow-up patch for these attributes?
Martin