Messages in this thread | | | Date | Mon, 2 Apr 2007 14:58:18 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [RFC] Cpu-hotplug: Using the Process Freezer (try2) |
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On Mon, Apr 02, 2007 at 08:16:12AM +0200, Ingo Molnar wrote: > hm, shouldnt the make be frozen immediately? > > doesnt the 'please freeze ASAP' flag get propagated to all tasks, > immediately? After that point any cloning activity should duplicate that > flag too, resulting in any new child freezing immediately too.
afaics, setting the 'please freeze asap' flag is racy wrt dup_task_struct (where the child's tsk->thread_info->flags are copied from its parent?). Secondly, from what I understand, it takes a 'flag to be set + signal marked pending' for the child task to be frozen. If that is the case, then copy_process may not propogae the signal to the child, which could mean mean that we can be in a catch-up game in freeze_processes, trying to freeze processes we didnt see in earlier passes.
I think copy_process() can check for something like this:
write_lock_irq(&tasklist_lock);
...
if (freezing(current)) freeze_process(p); /* function exported by freezer */
...
write_unlock_irq(&tasklist_lock);
-- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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