Re: [PATCH 0/8] dma-mapping: migrate to physical address-based API

Leon Romanovsky
2025-07-08T12:06:57Z

On Tue, Jul 08, 2025 at 01:45:20PM +0200, Marek Szyprowski wrote:
> On 08.07.2025 13:00, Leon Romanovsky wrote:
> > On Tue, Jul 08, 2025 at 12:27:09PM +0200, Marek Szyprowski wrote:
> >> On 30.06.2025 15:38, Christoph Hellwig wrote:
> >>> On Fri, Jun 27, 2025 at 08:02:13PM +0300, Leon Romanovsky wrote:
> >>>>> Thanks for this rework! I assume that the next step is to add map_phys
> >>>>> callback also to the dma_map_ops and teach various dma-mapping providers
> >>>>> to use it to avoid more phys-to-page-to-phys conversions.
> >>>> Probably Christoph will say yes, however I personally don't see any
> >>>> benefit in this. Maybe I wrong here, but all existing .map_page()
> >>>> implementation platforms don't support p2p anyway. They won't benefit
> >>>> from this such conversion.
> >>> I think that conversion should eventually happen, and rather sooner than
> >>> later.
> >> Agreed.
> >>
> >> Applied patches 1-7 to my dma-mapping-next branch. Let me know if one
> >> needs a stable branch with it.
> > Thanks a lot, I don't think that stable branch is needed. Realistically
> > speaking, my VFIO DMA work won't be merged this cycle, We are in -rc5,
> > it is complete rewrite from RFC version and touches pci-p2p code (to
> > remove dependency on struct page) in addition to VFIO, so it will take
> > time.
> >
> > Regarding, last patch (hmm), it will be great if you can take it.
> > We didn't touch anything in hmm.c this cycle and have no plans to send PR.
> > It can safely go through your tree.
>
> Okay, then I would like to get an explicit ack from Jérôme for this.

Jerome is not active in HMM world for a long time already.
HMM tree is managed by us (RDMA) https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/log/?h=hmm
➜ kernel git:(m/dmabuf-vfio) git log --merges mm/hmm.c
...
Pull HMM updates from Jason Gunthorpe:
...

https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=58ba80c4740212c29a1cf9b48f588e60a7612209
+hmm git git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git#hmm

We just never bothered to reflect current situation in MAINTAINERS file.

Thanks