The pmem driver don't honor a forced read-only setting for very long: $ blockdev --setro /dev/pmem0 $ blockdev --getro /dev/pmem0 1 followed by various commands like these: $ blockdev --rereadpt /dev/pmem0 or $ mkfs.ext4 /dev/pmem0 results in this in the kernel serial log: nd_pmem namespace0.0: region0 read-write, marking pmem0 read-write with the read-only setting lost: $ blockdev --getro /dev/pmem0 0 That's from bus.c nvdimm_revalidate_disk(), which always applies the setting from nd_region (which is initially based on the ACPI NFIT NVDIMM state flags not_armed bit). In contrast, commit 20bd1d026aac ("scsi: sd: Keep disk read-only when re-reading partition") fixed this issue for SCSI devices to preserve the previous setting if it was set to read-only. This patch modifies bus.c to preserve any previous read-only setting. It also eliminates the kernel serial log print except for cases where read-write is changed to read-only, so it doesn't print read-only to read-only non-changes. Signed-off-by: Robert Elliott <elliott(a)hpe.com&gt; --- drivers/nvdimm/bus.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c index a64023690cad..87762afa45b0 100644 --- a/drivers/nvdimm/bus.c +++ b/drivers/nvdimm/bus.c @@ -566,14 +566,17 @@ int nvdimm_revalidate_disk(struct gendisk *disk) { struct device *dev = disk_to_dev(disk)->parent; struct nd_region *nd_region = to_nd_region(dev->parent); - const char *pol = nd_region->ro ? "only" : "write"; + int disk_ro = get_disk_ro(disk); - if (nd_region->ro == get_disk_ro(disk)) + /* upgrade to read-only if the region is read-only + * preserve as read-only if the disk is already read-only + */ + if (disk_ro || nd_region->ro == disk_ro) return 0; - dev_info(dev, "%s read-%s, marking %s read-%s\n", - dev_name(&nd_region->dev), pol, disk->disk_name, pol); - set_disk_ro(disk, nd_region->ro); + dev_info(dev, "%s read-only, marking %s read-only\n", + dev_name(&nd_region->dev), disk->disk_name); + set_disk_ro(disk, 1); return 0; -- 2.14.3