Re: [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices

From: Jason Gunthorpe
Date: Tue Sep 28 2021 - 16:02:22 EST

On Thu, Sep 16, 2021 at 05:40:40PM -0600, Logan Gunthorpe wrote:
> Hi,
> This patchset continues my work to add userspace P2PDMA access using
> O_DIRECT NVMe devices. My last posting[1] just included the first 13
> patches in this series, but the early P2PDMA cleanup and map_sg error
> changes from that series have been merged into v5.15-rc1. To address
> concerns that that series did not add any new functionality, I've added
> back the userspcae functionality from the original RFC[2] (but improved
> based on the original feedback).

I really think this is the best series yet, it really looks nice
overall. I know the sg flag was a bit of a debate at the start, but it
serves an undeniable purpose and the resulting standard DMA APIs 'just
working' is really clean.

There is more possible here, we could also pass the new GUP flag in the
ib_umem code..

After this gets merged I would make a series to split out the CMD
genalloc related stuff and try and probably get something like VFIO to
export this kind of memory as well, then it would have pretty nice