blk-mq/nvme: fix debugfs creation with frozen queue #550
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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. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
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. Reported-by: Yi Zhang <yi.zhang@redhat.com> Closes: https://lore.kernel.org/all/CAHj4cs9gNKEYAPagD9JADfO5UH+OiCr4P7OO2wjpfOYeM-RV=A@mail.gmail.com/ Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
blk_mq_update_nr_hw_queues() freezes and unfreezes queues internally. When the queue is already frozen before this call (from nvme_start_freeze in apple_nvme_disable), 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. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Replace the freeze depth check with blk_queue_enter()/blk_queue_exit() which properly waits for the queue to be unfrozen and prevents new freezes while creating debugfs files. This provides correct synchronization without false warnings. If the queue is dying (blk_queue_enter returns error), skip creating the debugfs files as the queue is being torn down anyway. Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Closes: https://lore.kernel.org/all/aYWQR7CtYdk3K39g@shinmob/ Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
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Upstream branch: 8160585 |
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Pull request for series with
subject: blk-mq/nvme: fix debugfs creation with frozen queue
version: 1
url: https://patchwork.kernel.org/project/linux-block/list/?series=1052172