Maurice reports:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: holder_class_store+0x253/0x2b0 [libnvdimm]
...while trying to reconfigure an NVDIMM-N namespace into 'sector' /
'btt' mode. The crash points to this line:
(gdb) li *(holder_class_store+0x253)
0x7773 is in holder_class_store (drivers/nvdimm/namespace_devs.c:1420).
1415 for (i = 0; i < nd_region->ndr_mappings; i++) {
1416 struct nd_mapping *nd_mapping = &nd_region->mapping[i];
1417 struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
1418 struct nd_namespace_index *nsindex;
1419
1420 nsindex = to_namespace_index(ndd, ndd->ns_current);
...where we are failing because ndd is NULL due to NVDIMM-N dimms not
supporting labels.
Long story short, default to the BTTv1 format in the label-less /
NVDIMM-N case.
Fixes: 14e4945426 ("libnvdimm, btt: BTT updates for UEFI 2.7 format")
Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Reported-by: Maurice A. Saldivar <maurice.a.saldivar@hpe.com>
Tested-by: Maurice A. Saldivar <maurice.a.saldivar@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
33a5608671