Quoting Louis Rilling (Louis.Rilling@xxxxxxxxxxx): > On Tue, Mar 23, 2010 at 12:18:39AM -0500, Serge E. Hallyn wrote: > > Support checkpoint and restart of tasks in nested pid namespaces. > > We keep the original single pids_array to minimize memory > > allocations. The pids array entries are augmented with a pidns > > depth (relative to the container init's pidns, and an "rpid" which > > is the pid in the checkpointer's pidns (or 0 if no valid pid exists). > > The rpid will be used by userspace to gather more information (like > > /proc/$$/mountinfo) after the kernel sys_checkpoint. If any tasks > > are in nested pid namespace, another single array will hold all of > > the vpids. At restart those are used by userspace to determine how > > to call eclone(). Kernel ignores them. > > > > This patch also adds 'rpid' to struct ckpt_hdr_pids, which is not > > needed for nested pid_ns support, but will be needed for the > > userspace checkpointer to gather additional information (i.e. > > /proc/pid/mountinfo) after sys_checkpoint() completes. > > > > Changelog: > > Mar 22: > > Use Louis Rilling's smarter ckpt_vpids algorithm > > verbatim, to handle pid_ns depths > CKPT_HDR_PIDS_CHUNK, > > as well as fix an apparent bug in my original code. > > > > As Louis suggested, use task_active_pid_ns() rather than > > task->nsproxy->pid_ns. In fact it's a must, bc the > > checkpointed task may be dead and have NULL > > task->nsproxy->pid_ns. > > Hm, if task can be dead, then there is a much bigger issue: > task->nsproxy is NULL. Or did I miss something? Well, it's a zombie - checkpoint/checkpoint.c:may_checkpoint_task() explicitly ignores nsproxy tests for zombies (but returns -EBUSY for exit_state == EXIT_DEAD). So yeah, nsproxy is NULL, which is why I have to use task_active_pid_ns() :) -serge _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
