On 05.08.22 19:55, Paolo Bonzini wrote: > On 7/21/22 11:44, David Hildenbrand wrote: >> >> Also, I*think* you can place pages via userfaultfd into shmem. Not >> sure if that would count "auto alloc", but it would certainly bypass >> fallocate(). > > Yeah, userfaultfd_register would probably have to forbid this for > F_SEAL_AUTO_ALLOCATE vmas. Maybe the memfile_node can be reused for > this, adding a new MEMFILE_F_NO_AUTO_ALLOCATE flags? Then > userfault_register would do something like > memfile_node_get_flags(vma->vm_file) and check the result. An alternative is to simply have the shmem allocation fail in a similar way. Maybe it does already, I haven't checked (don't think so). -- Thanks, David / dhildenb
