Hi! In previous series EPOLL_CTL_DUP operation has been discussed but considered as potentially scary. So here is an another approach: - extend fdinfo of epoll files with inode, device and file position for every target, which allow the reader to gather targets with this bundle as a key for primary sorting - extent kcmp to check if some particular file is matching one sitting inside epoll queue (duplicate numbers are resolved with offset parameter) Please take a look once time permit. Note that I did only basic testing (without CRIU) but it should fit our needs because we sort and lookup regualr files by same scheme. So I'm about to implemet full criu support for this new kernel features in a couple of days thus any comments are *higly* appreciated. NB: Initially I added if (file_ns_capable(epi->ffd.file, ns, CAP_SYS_ADMIN)) into fdinfo output to check if caller is allowed to see target ino/dev/pos but dropped it later because if process is added file descriptor into epoll queue it mean fdstat and such already can be called and this information is already obtained, so I don't this it's information disclosure. Cyrill
