Messages in this thread | | | Date | Fri, 28 Jul 2023 14:32:12 -0700 | Subject | Re: [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout | From | John Hubbard <> |
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On 7/28/23 14:20, Peter Xu wrote: > On Fri, Jul 28, 2023 at 11:02:46PM +0200, David Hildenbrand wrote: >> Can we get a simple revert in first (without that FOLL_FORCE special casing >> and ideally with a better name) to handle stable backports, and I'll >> follow-up with more documentation and letting GUP callers pass in that flag >> instead? >> >> That would help a lot. Then we also have more time to let that "move it to >> GUP callers" mature a bit in -next, to see if we find any surprises? > > As I raised my concern over the other thread, I still worry numa users can > be affected by this change. After all, numa isn't so uncommon to me, at > least fedora / rhel as CONFIG_NUMA_BALANCING_DEFAULT_ENABLED=y. I highly > suspect that's also true to major distros. Meanwhile all kernel modules > use gup.. > > I'd say we can go ahead and try if we want, but I really don't know why > that helps in any form to move it to the callers.. with the risk of > breaking someone.
It's worth the trouble, in order to clear up this historical mess. It's helping *future* callers of the API, and future maintenance efforts. Yes there is some risk, but it seems very manageable.
The story of how FOLL_NUMA and FOLL_FORCE became entangled was enlightening, by the way, and now that I've read it I don't want to go back. :)
thanks, -- John Hubbard NVIDIA
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