On Fri, Feb 12, 2021 at 10:21:45PM +0000, Matthew Wilcox wrote: > On Thu, Feb 11, 2021 at 11:28:09AM -0800, Axel Rasmussen wrote: > > Ah, I had added this just after VM_UFFD_WP, without noticing that this > > would be sharing a bit with VM_LOCKED. That seems like not such a > > great idea. > > > > I don't see another unused bit, and I don't see some other obvious > > candidate to share with. So, the solution that comes to mind is > > it'd be even better if you didn't use the last unused bit for UFFD_WP. > not sure how feasible that is, but you can see we're really short on > bits here. UFFD_WP is used now for anonymouse already.. And the support for hugetlbfs and shmem is in rfc stage on the list. Is it possible to use CONFIG_ARCH_USES_HIGH_VMA_FLAGS here? So far uffd-wp is only working for 64 bit x86 too due to enlarged pte space. Maybe we can also let minor mode to only support 64 bit hosts. Thanks, -- Peter Xu
