Thanks for replying to my email, my description in the last email was not clear enough, so here's a supplementary note.
The NVME device I used support DBBUF, but the nvme_admin_dbbuf request returned a failure that eventually led to the kernel crash. The problem occurs as follows: 1, Device support NVME_CTRL_OACS_DBBUF_SUPP,so reset worker alloc memory for dev->dbbuf_dbs。 2, In nvme_setup_io_queues process, the nvme_dbbuf_init function is called to assign values to pointers such as nvmeq->dbbuf_sq_db. 3, In nvme_dev_add function, the nvme_admin_dbbuf request is sent to the device, but the device returns failed, so the memory that dev->dbbuf_dbs points to is released. Then, the driver issued IO requests, in the nvme_write_sq_db process, nvme_dbbuf_update_and_check_event function judgment to Nvmeq->dbbuf_sq_db pointer is not NULL, write to the memory it points to, causing memory confusion and kernel crash. On 2019/1/5 2:07, Christoph Hellwig wrote: > On Fri, Dec 21, 2018 at 01:07:25AM +0000, Lulina (A) wrote: >> The case is that nvme device support NVME_CTRL_OACS_DBBUF_SUPP, and >> return failed when the driver sent nvme_admin_dbbuf. The nvmeq->dbbuf_sq_db >> point to freed memory, as nvme_dbbuf_set is called after nvme_dbbuf_init. > > But we never use those pointers in that state, do we? Can you explain > the problem in a little more detail? > >