Re: [RFC 0/8] Define coherent device memory node

On Wed, Oct 26, 2016 at 04:39:19PM +0530, Aneesh Kumar K.V wrote:

Jerome Glisse [off-list ref] writes:

quoted

On Tue, Oct 25, 2016 at 09:56:35AM +0530, Aneesh Kumar K.V wrote:

quoted

Jerome Glisse [off-list ref] writes:

quoted

On Mon, Oct 24, 2016 at 10:01:49AM +0530, Anshuman Khandual wrote:

I looked at the hmm-v13 w.r.t migration and I guess some form of device
callback/acceleration during migration is something we should definitely
have. I still haven't figured out how non addressable and coherent device
memory can fit together there. I was waiting for the page cache
migration support to be pushed to the repository before I start looking
at this closely.

The page cache migration does not touch the migrate code path. My issue with
page cache is writeback. The only difference with existing migrate code is
refcount check for ZONE_DEVICE page. Everything else is the same.

What about the radix tree ? does file system migrate_page callback handle
replacing normal page with ZONE_DEVICE page/exceptional entries ?

It use the exact same existing code (from mm/migrate.c) so yes the radix tree
is updated and buffer_head are migrated.

Jerome

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