Re: [PATCH v3 01/11] pagemap: Introduce ->memory_failure()

[Christoph Hellwig]

On Tue, Mar 23, 2021 at 07:19:28PM -0700, Dan Williams wrote:
> So I think the path forward is:
> 
> - teach memory_failure() to allow for ranged failures
> 
> - let interested drivers register for memory failure events via a
> blocking_notifier_head

Eww.  As I said I think the right way is that the file system (or
other consumer) can register a set of callbacks for opening the device.
I have a series I need to finish and send out to do that for block
devices.  We probably also need the concept of a holder for the dax
device to make it work nicely, as otherwise we're going to have a bit
of a mess.

> This obviously does not solve Dave's desire to get this type of error
> reporting on block_devices, but I think there's nothing stopping a
> parallel notifier chain from being created for block-devices, but
> that's orthogonal to requirements and capabilities provided by
> dax-devices.

FYI, my series could easily accomodate that if we ever get a block
driver that actually could report such errors.