May nvme_get_ns_from_disk introduce deadlock?

[Wang Sheng-Hui]

Hi,

I'm reading the code, and found that nvme_get_ns_from_disk *may* 
introduce deadlock by invoking nvme_free_ns in core.c (nested
spin_lock(&dev_list_lock) ). 
But I can't figure out which condition can lead to deadlock.

Will someone help to explain the code that how can it escape from deadlock?

Thanks,
Wang Sheng-Hui