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

Dan Williams
2017-04-27T22:27:00Z

On Thu, Apr 27, 2017 at 3:25 PM, Kani, Toshimitsu <toshi.kani@hpe.com> wrote:
> 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().

Argh, yes, we don't populate them out to the disk badblocks. I'll go
with your patch.