On Tue, May 21, 2019 at 05:30:27PM +0100, David Howells wrote: > If we can live with close_from(int first) rather than close_range(), then this > can perhaps be done a lot more efficiently by: > > new = alloc_fdtable(first); > spin_lock(&files->file_lock); > old = files_fdtable(files); > copy_fds(new, old, 0, first - 1); > rcu_assign_pointer(files->fdt, new); > spin_unlock(&files->file_lock); > clear_fds(old, 0, first - 1); > close_fdt_from(old, first); > kfree_rcu(old); I really hate to think how that would interact with POSIX locks...