Re: [PATCH] libnvdimm, pmem: fix badblocks notification crash

On Thu, 2017-04-27 at 15:10 -0700, Dan Williams wrote: > The nd_pmem_notify() routine is called whenever an ARS > (address-range-scrub) completes to communicate results to the > per-namespace badblocks instances. > > When the namespace is in btt mode we crash because we do not allocate > a struct pmem_device instance in that case. Resulting in the > following crash signature: > > BUG: unable to handle kernel NULL pointer dereference at > 0000000000000030 > IP: nd_pmem_notify+0x30/0xf0 [nd_pmem] > Call Trace: > nd_device_notify+0x40/0x50 > child_notify+0x10/0x20 > device_for_each_child+0x50/0x90 > nd_region_notify+0x20/0x30 > nd_device_notify+0x40/0x50 > nvdimm_region_notify+0x27/0x30 > acpi_nfit_scrub+0x341/0x590 [nfit] > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > > Given that we don't even populate the btt badblocks instance, just > return early and skip the device to region lookup. We populate the btt badblocks into nsio->bb, and check/clear them in nsio_rw_bytes().