Messages in this thread | | | Date | Mon, 28 Nov 2011 18:43:37 +0300 | Subject | Re: [RFC] cgroups: freezer -- Allow to attach a task to a frozen cgroup | From | Andrew Wagin <> |
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> >> > > >> > > It's strange. A rollback can't fail. We have three situations: >> > > >> > > frozen -> frozen >> > > thawed -> frozen >> > > frozen -> thawed >> > > >> > > In first and second cases cancel_request can't fail. >> > > In the third we have a problem, which may be solved if we will call >> > > thaw_process(task) from attach_task(), we can do that, because >> > > thaw_process() can't fail. It solves a problem, because >> > > freezer_cancel_attach will be executed for the first and second cases >> > > only. >> > > >> > > If my suggestion is correct, we can replace pr_warning on BUG_ON >> > > >> > >> > Yes, the case which can fail is >> > >> > frozen->(can_attach_task)->thawed >> > (cgroup_task_migrate failure) >> > thawed->(cancel_attach)->frozen >> > >> > and we should never fail here since otherwise we would not have >> > a "frozen" state before. But I think placing BUG_ON is too severe >> > here, maybe WARN_ON_ONCE(1) would fit better? >> >> It's true, if a task is not being executed between thaw_process() and >> freeze_task(). > > Hmm... But what the problem it might be if a task get executed between > those stages even for some time?
It may become unfreezable...
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