Re: [PATCH 0/6] RFC v2: mm: gup/dma tracking

From: Jason Gunthorpe
Date: Mon Feb 04 2019 - 12:51:18 EST

On Mon, Feb 04, 2019 at 05:14:19PM +0000, Christopher Lameter wrote:
> Frankly I still think this does not solve anything.
> Concurrent write access from two sources to a single page is simply wrong.
> You cannot make this right by allowing long term RDMA pins in a filesystem
> and thus the filesystem can never update part of its files on disk.

Fundamentally this patch series is fixing O_DIRECT to not crash the
kernel in extreme cases.. RDMA has the same problem, but it is much
easier to hit.

I think questions related to RDMA are somewhat separate, and maybe it
should be blocked, or not, but either way O_DIRECT has to be fixed.