On Fri, 2018-07-13 at 15:29 +0200, Patrick Steinhardt wrote: > When power management for SCSI is enabled and if a device uses blk-mq, > it is possible to trigger a `NULL` pointer exception when resuming that > device. The NPE is triggered when trying to dereference the `request_fn` > function pointer of the device's `request_queue`: > > __blk_run_queue_uncond:470 > __blk_run_queue:490 > blk_post_runtime_resume:3889 > sdev_runtime_resume:263 > scsi_runtime_resume:275 > > When the SCSI device is being allocated by `scsi_alloc_sdev`, the > device's request queue will either be initialized via > `scsi_mq_alloc_queue` or `scsi_old_alloc_queue`. But the `request_fn` > member of the request queue is in fact only being set in > `scsi_old_alloc_queue`, which will then later cause the mentioned NPE. > > Fix the issue by checking whether the `request_fn` is set in > `__blk_run_queue_uncond`. In case it is unset, we'll silently return and > not try to invoke the callback, thus fixing the NPE.
Which kernel version are you using? Can you check whether the following two commits are in your kernel tree? * 4fd41a8552af ("SCSI: Fix NULL pointer dereference in runtime PM"; December 2015). * 765e40b675a9 ("block: disable runtime-pm for blk-mq"; July 2017). Thanks, Bart.