Quoting Oren Laadan (orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org):

Serge E. Hallyn wrote:

quoted

Quoting Oren Laadan (orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org):

quoted

Now we can do "external" checkpoint, i.e. act on another task.

...

quoted

 long do_checkpoint(struct ckpt_ctx *ctx, pid_t pid)
 {
 	long ret;

+	ret = init_checkpoint_ctx(ctx, pid);
+	if (ret < 0)
+		return ret;
+
+	if (ctx->root_freezer) {
+		ret = cgroup_freezer_begin_checkpoint(ctx->root_freezer);
+		if (ret < 0)
+			return ret;
+	}

Self-checkpoint of a task in root freezer is now denied, though.

Was that intentional?

Yes.

"root freezer" is an arbitrary task in the checkpoint subtree or
container. It is used to verify that all checkpointed tasks - except
for current, if doing self-checkpoint - belong to the same freezer
group.

Since current is busy calling checkpoint(2), and since we only permit
checkpoint of (cgroup-) frozen tasks, then - by definition - it cannot
possibly belong to the same group. If it did, it would itself be frozen
like its fellows and unable to call checkpoint(2).

So then you're saying that regular self-checkpoint no longer works,
but the documentation still shows self.c and claims it should just
work.

Mind you I prefer this as it is more consistent, but I thought it
was something you wanted to support.

-serge