Re: [PATCH 1/4] nvme-rdma: move blk_mq_update_nr_hw_queues after nvme_unfreeze

[Christoph Hellwig <hch@lst.de>]

On Mon, Feb 09, 2026 at 04:29:50PM +0800, Yu Kuai wrote:
> blk_mq_update_nr_hw_queues() freezes and unfreezes queues internally.
> When the queue is already frozen before this call, the freeze depth
> becomes 2. The internal unfreeze only decrements it to 1, leaving the
> queue still frozen when debugfs_create_files() is called.
> 
> This triggers WARN_ON_ONCE(q->mq_freeze_depth != 0) in
> debugfs_create_files() and risks deadlock.
> 
> Fix this by moving nvme_unfreeze() before blk_mq_update_nr_hw_queues()
> so the queue is unfrozen before the call, allowing the internal
> freeze/unfreeze to work correctly.

After this nothing is really protected by the frozen queue except
for unquiescing the I/O queues.  So we can probably eventually
drop it, but it might make sense to avoid that for now.

Reviewed-by: Christoph Hellwig <hch@lst.de>