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    SubjectRe: v3.4-rc2 out-of-memory problems (was Re: 3.4-rc1 sticks-and-crashs)
    On Mon, 9 Apr 2012, Linus Torvalds wrote:

    > > You could that if you also turned the check for "ret == NOTIFY_OK" in
    > > profile_handoff_task() into "ret & NOTIFY_OK" in your patch, otherwise you
    > > get a double free from __put_task_struct() and oprofile.
    > Why? NOTIFY_DONE is zero.

    Oops, right.

    > >  (1)  fix the lowmemorykiller so it doesn't need to use these notifiers at
    > >      all, which isn't difficult, for 3.4, then
    > I do think that that makes sense. Fixing people to not use notifiers
    > is always a good idea. Why would anybody sane even care about the
    > process going away anyway? If some lowmemorykiller decides to kill off
    > a process that no longer exists, kill() should happily return ENOSRCH,
    > and we're all good

    It's apparently waiting for a killed thread to exit before selecting
    another victim or the one second timeout expires. (And you only get to
    prevent needless kills if you have CONFIG_PROFILING, otherwise it doesn't

    > At the same time, the *only* user of that stupid handoff thing is
    > oprofile, afaik, and if we use a refcount, why the hell doesn't
    > oprofile just use a refcount to begin with, instead of using that
    > notifier?: IOW, *both* users of the notifier seem to be just retarded.

    Agreed and since the current implementation relies on CONFIG_PROFILING I
    think it's safe to remove the notifier and add a hook only for oprofile so
    it can do free_task() when it wants to. No refcounting required.

    I've already proposed a patch that removes the notifier for
    lowmemorykiller with the added benefit that it doesn't rely on
    CONFIG_PROFILING at all. If that's merged for 3.4, I'll remove the task
    handoff callchain entirely for 3.5 since oprofile is the only user.
     \ /
      Last update: 2012-04-10 02:07    [W:0.022 / U:21.360 seconds]
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