From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Serge E. Hallyn" Subject: [PATCH 0/2] sys_restore prototype Date: Fri, 25 Jul 2008 17:56:56 -0500 Message-ID: <20080725225655.GA28276@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Linux Containers List-Id: containers.vger.kernel.org We were talking this morning about what trivial patchset to begin with to get a start on checkpoint and restart. We thought that rather than start with checkpoint, maybe we should start with something that reads a "checkpoint file" and "restarts" a single task. In this case, restart means it sets the process id and executes the file which are found in the checkpoint file. So here's what we whipped up for a half hour this morning, and during some of Mark's talk this afternoon. It refuses to run if it isn't the container init, so you must unshare your pidns before calling sys_restore(). To test, I did: [root@kvm-f9 ~]# cat mycheckpoint 99 /root/whoami [root@kvm-f9 ~]# cat restore.c #include #include #include #include int main() { int ret; char *argv[3]; char *envp[1]; //argv[0] = argv[1] = "/bin/bash"; //argv[2] = envp[0] = NULL; argv[0] = "/root/whoami"; argv[1] = envp[0] = NULL; int fd = open("/root/mycheckpoint", O_RDONLY); if (fd < 0) perror("open checkpoint file"); ret = syscall(327, fd, argv, envp); printf("syscall returned %d\n", ret); perror("syscall for checkpoint"); close(fd); return ret; } [root@kvm-f9 ~]# cat whoami.c #include #include #include int main() { printf("I am %d\n", getpid()); return 0; } Next, I create a new pid namespace, remount /proc, and execute 'restore' using 'exec' so that pid 1 is doing it: [root@kvm-f9 ~]# /home/hallyn/cryo/utils/ns_exec -cp /bin/bash about to clone with 20020000 [root@kvm-f9 ~]# mount -t proc none /proc [root@kvm-f9 ~]# ps -ef UID PID PPID C STIME TTY TIME CMD root 1 0 1 18:46 pts/0 00:00:00 /bin/bash root 26 1 0 18:46 pts/0 00:00:00 ps -ef [root@kvm-f9 ~]# exec ./restore I am 99 Seems to work. -serge