On Tue, Jun 24, 2025 at 01:48:50PM +0200, David Hildenbrand wrote: > The man page was updated with > > commit db3d5cc1a17b0ace008ebe1eaf0ac4d96b4b519a > Author: Axel Rasmussen <[email protected]> > Date: Tue Oct 3 12:45:44 2023 -0700 > > ioctl_userfaultfd.2: Correct and update UFFDIO_API ioctl error codes > First, it is not correct that repeated UFFDIO_API calls result in > EINVAL. This is true *if both calls enable features*, but in the case > where we're doing a two-step feature detection handshake, the kernel > explicitly expects 2 calls (one with no features set). So, correct this > description. > Then, some new error cases have been added to the kernel recently, and > the man page wasn't updated to note these. So, add in descriptions of > these new error cases. > > @Axel, did you ignore the automatically-set UFFD_FEATURE_INITIALIZED and the > repeated calls never worked, or was there actually a time where repeated > UFFDIO_API calls would not result in EINVAL?
The man-pages was inaccurate before. It got updated recently after Kyle asking similar questions, see: http://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?id=6a949e9b08fd1ad4e77584276b9566e45fc07a93 Li's v2 change on using the temp fd looks correct. Thanks, -- Peter Xu
