Quoting Dave Hansen (dave@xxxxxxxxxxxxxxxxxx): > On Tue, 2009-02-24 at 07:47 +0300, Alexey Dobriyan wrote: > > > I think what I posted is a decent compromise. It gets you those > > > warnings at runtime and is a one-way trip for any given process. But, > > > it does detect in certain cases (fork() and unshare(FILES)) when it is > > > safe to make the trip back to the "I'm checkpointable" state again. > > > > "Checkpointable" is not even per-process property. > > > > Imagine, set of SAs (struct xfrm_state) and SPDs (struct xfrm_policy). > > They are a) per-netns, b) persistent. > > > > You can hook into socketcalls to mark process as uncheckpointable, > > but since SAs and SPDs are persistent, original process already exited. > > You're going to walk every process with same netns as SA adder and mark > > it as uncheckpointable. Definitely doable, but ugly, isn't it? > > > > Same for iptable rules. > > > > "Checkpointable" is container property, OK? > > Ideally, I completely agree. > > But, we don't currently have a concept of a true container in the > kernel. Do you have any suggestions for any current objects that we > could use in its place for a while? I think the main point is that it makes the concept of marking a task as uncheckpointable unworkable. So at sys_checkpoint() time or when we cat /proc/$$/checkpointable, we can check for all of the uncheckpointable state of both $$ and its container (including whether $$ is a container init). But we can't expect that (to use Alexey's example) when one task in a netns does a certain sys_socketcall, all tasks in the container will be marked uncheckpointable. Or at least we don't want to. Which means task->uncheckpointable can't be the big stick which I think you were hoping it would be. -serge -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
