On Fri, Oct 21, 2022 at 04:36:51PM +0000, James Houghton wrote: > @@ -1990,6 +1990,17 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, > ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); > #ifndef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING > uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS_HGM; > +#else > + > + ret = -EINVAL; > + if ((uffdio_api.features & UFFD_FEATURE_MINOR_HUGETLBFS_HGM) && > + !(uffdio_api.features & UFFD_FEATURE_EXACT_ADDRESS)) This check needs to be done upon "features" or "ctx_features", rather than "uffdio_api.features". The latter is the one we'll report to the user only. > + /* > + * UFFD_FEATURE_MINOR_HUGETLBFS_HGM is mostly > + * useless without UFFD_FEATURE_EXACT_ADDRESS, > + * so require userspace to provide both. > + */ > + goto err_out; > #endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */ > #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ > > -- > 2.38.0.135.g90850a2211-goog > > -- Peter Xu
