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. Logically it should also be always better to migrate earlier than later, not only because the page will be local earlier, but also per I discussed also in the other thread (that the gup can hold a ref to the page, and it could potentially stop numa balancing to succeed later). Thanks, -- Peter Xu
