On Fri, Apr 14, 2023, Sean Christopherson wrote: > On Fri, Apr 14, 2023, Ackerley Tng wrote: > > Sean Christopherson <seanjc@xxxxxxxxxx> writes: > > > if (WARN_ON_ONCE(file->private_data)) { > > > err = -EEXIST; > > > goto err_fd; > > > } > > > > Did you intend this as a check that the backing filesystem isn't using > > the private_data field in the mapping? > > > > I think you meant file->f_mapping->private_data. > > Ya, sounds right. I should have added disclaimers that (a) I wrote this quite > quickly and (b) it's compile tested only at this point. FWIW, here's a very lightly tested version that doesn't explode on a basic selftest. https://github.com/sean-jc/linux/tree/x86/upm_base_support