Re: [PULL] topic/iomem-mmap-vs-gup

On Mon, May 10, 2021 at 9:30 AM Christoph Hellwig [off-list ref] wrote:

On Mon, May 10, 2021 at 09:16:58AM +0200, Daniel Vetter wrote:

quoted

quoted

End result: not pulling it, unless somebody can explain to me in small
words why I'm wrong and have the mental capacity of a damaged rodent.

No rodents I think, just more backstory of how this all fits. tldr;
pin_user_pages is the only safe use of this vb2 userptr thing.

Yes, which is why I advocate for just ripping the follow_pfn path
out entirely.  It could have been used for crazy ad dangerous peer to
peer transfers outside of any infrastructure making it safe, or for
pre-CMA kernel memory carveouts for lage contiguous memory allocations
(which are pretty broken by design as well).  So IMHO the only sensible
thing is to remove this cruft entirely, and if it breaks a currently
working setup (which I think is unlikely) we'll have to make sure it
can work the proper way.

Since I'm not getting any cozy consenus vibes here on any option I
think I'll just drop this.

Stephen, can you pls drop

git://anongit.freedesktop.org/drm/drm topic/iomem-mmap-vs-gup

from linux-next? It's not going anywhere. I'll also go ahead and
delete the branch, to make sure you catch this update :-)

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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