When a region is disabled, there is no driver attached. Therefore dev->driverdata is NULL. An attempt to write to regionN/deep_flush via sysfs would cause a NULL pointer dereference. Bail when dev->driver is NULL to protect this scenario. Fix: ab630891ce0eb(libnvdimm, region: sysfs trigger for nvdimm_flush()) Signed-off-by: Dave Jiang <dave.jiang(a)intel.com&gt; --- drivers/nvdimm/region_devs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index a612be6f019d..d5619b7feb6a 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -1074,6 +1074,10 @@ void nvdimm_flush(struct nd_region *nd_region) struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev); int i, idx; + /* protect against disabled region */ + if (!nd_region->dev.driver) + return; + /* * Try to encourage some diversity in flush hint addresses * across cpus assuming a limited number of flush hints.