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    SubjectRe: OK to set PF_MEMDIE on cleanup tasks?
    "Paul E. McKenney" <> wrote:
    > Hello!
    > We have tasks that actively return memory to the system, which we
    > would like to exempt from the OOM killer, as killing such tasks under
    > low-memory conditions would indeed be counterproductive. It looks like
    > the "official" way to do this is to catch/ignore signal 15, which results
    > in PF_MEMDIE being set (in the 2.6 kernel), thus preventing the OOM killer
    > from killing the task again. I don't see where PF_MEMDIE is cleared,
    > though there are a number of subtle ways one might do this that I would
    > have missed.

    The PF_MEMDIE flag is there so the oom killer doesn't just sit there
    hitting the same task over and over again.

    We leave PF_MEMDIE set because we expect the task to exit, or to not want
    any more oomkiller attention.

    The SIGTERM behaviour is there because the CAP_SYS_RAWIO process may need
    to release critical resources.

    So as long as your process has CAP_SYS_RAWIO, everything happens to work as
    you want it. I don't think it was really designed that way though.

    > So... Is it considered legit to simply set PF_MEMDIE when creating
    > the cleanup task? Or is there some reason that one should deal with
    > signal 15?

    Well it's all very unconventional. Catching SIGTERM seems like a suitable
    way to do what you want to do.

    Possibly your special process should also run as PF_MEMALLOC. I've seen
    that done before, with success. There is no existing API with which this
    can be set.

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