On Mon, Jul 22, 2019 at 08:25:07AM -0700, Bart Van Assche wrote: > 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. The above commit log has explained that there isn't sync mechanism in blk-mq wrt. request completion, and there might be similar issue in other future drivers. Thanks, Ming
