Re: [PATCH 2/3] block: Add badblock management for gendisks

[Jeff Moyer <jmoyer@redhat.com>]

"Verma, Vishal L" <vishal.l.verma@intel.com> writes:

> On Tue, 2015-11-24 at 10:34 -0500, Jeff Moyer wrote:
>> Vishal Verma <vishal.l.verma@intel.com> writes:
>> 
>> > NVDIMM devices, which can behave more like DRAM rather than block
>> > devices, may develop bad cache lines, or 'poison'. A block device
>> > exposed by the pmem driver can then consume poison via a read (or
>> > write), and cause a machine check. On platforms without machine
>> > check recovery features, this would mean a crash.
>> > 
>> > The block device maintaining a runtime list of all known sectors
>> > that
>> > have poison can directly avoid this, and also provide a path forward
>> > to enable proper handling/recovery for DAX faults on such a device.
>> > 
>> > Use the new badblock management interfaces to add a badblocks list
>> > to
>> > gendisks.
>> 
>> Because disk_alloc_badblocks can fail, you need to check for a NULL
>> disk->bb in all of the utility functions you've defined.
>> 
>
> Thanks, Jeff - I'll fix this. I have a handful of other fixes queued up
> too, will send out a v2 soon.

I'm not sure whether it makes sense to continue without badblock
management for the RAID code.  I was hoping Neil would comment on that.

-Jeff