Changes

* Tasks after restore should have lazy VMAs being backed by userfaultfd, the fd itself should be sent before resume to CRIU daemon and closed

* Tasks after restore should have lazy VMAs being backed by userfaultfd, the fd itself should be sent before resume to CRIU daemon and closed

* Only MAP_PRIVATE | MAP_ANONYMOUS will be supported in the 1st version due to kernel constraints

* Only MAP_PRIVATE | MAP_ANONYMOUS will be supported in the 1st version due to kernel constraints

* On source side the [[page server]] should be taught to use page-read to send pages out on the destination one

* On source side the [[page server]] should be taught to get pages from tasks dumped and send them out on the destination node

* Protocol should include out-of-order pages and background pages pushing (sending them before demand from the process)

* Protocol should include out-of-order pages and background pages pushing (sending them before demand from the process)

* The now dump-only <code>--page-server</code> option should be used for restore action to tell that the memory will be sucked in through page server

* The now dump-only <code>--page-server</code> option should be used for restore action to tell that the memory will be sucked in through page server