On 7/21/19 10:39 PM, Ming Lei wrote:
blk-mq may schedule to call queue's complete function on remote CPU via IPI, but doesn't provide any way to synchronize the request's complete fn. In some driver's EH(such as NVMe), hardware queue's resource may be freed & re-allocated. If the completed request's complete fn is run finally after the hardware queue's resource is released, kernel crash will be triggered. Prepare for fixing this kind of issue by introducing blk_mq_tagset_wait_completed_request().
An explanation is missing of why the block layer is modified to fix this instead of the NVMe driver.
Thanks, Bart.
